• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
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    • 专利摘要:
    The invention relates to a device (1) for detecting electromagnetic radiation, comprising a read circuit (10) located in a substrate (2) and an electrical connection pad (30) arranged on the substrate. having a metal portion (31) raised above the substrate and electrically connected to the read circuit. The detection device further comprises a protective wall (34) extending under the raised metal portion so as to define therewith at least a portion of a cavity (3), and a portion (4) of layer, said reinforcement, located in the cavity, on which rests the raised metal portion.
    公开号:FR3048125A1
    申请号:FR1651511
    申请日:2016-02-24
    公开日:2017-08-25
    发明作者:Stephane Pocas；Agnes Arnaud；Sebastien Cortial；Jean-Jacques Yon
    申请人:Commissariat a lEnergie Atomique CEA；Ulis SAS；Commissariat a lEnergie Atomique et aux Energies Alternatives CEA；
    IPC主号:
    专利说明:

    DEVICE FOR DETECTING ELECTROMAGNETIC RADIATION WITH PLATE OF
    SLELEVE ELECTRICAL CONNECTION
    TECHNICAL AREA
    The field of the invention is that of devices for detecting electromagnetic radiation, in particular infrared or terahertz, comprising at least one raised electrical connection pad above a substrate containing a read circuit. The invention applies in particular to the field of imaging and infrared thermography.
    STATE OF THE PRIOR ART
    A device for detecting electromagnetic radiation, for example infrared or terahertz, usually comprises a matrix of thermal detectors, said elementary, each detector having a portion capable of absorbing the electromagnetic radiation to be detected.
    In order to insure the thermal insulation of the thermal detectors, the portions are usually in the form of membranes suspended above the substrate by anchoring pillars, and are thermally insulated therefrom by the arms. thermal insulation. These anchoring pillars and isolation arms also have an electrical function by electrically connecting the suspended membranes to a reading circuit generally disposed in the substrate.
    The read circuit is usually in the form of a CMOS circuit. It allows the application of a control signal to the thermal detectors as well as the reading of detection signals generated by the thermal detectors in response to the absorption of the electromagnetic radiation to be detected. The read circuit comprises different levels of electrical interconnection formed of metal lines electrically insulated from each other by so-called inter-metal dielectric layers. An electrical connection pad of the read circuit is disposed on the substrate so that it can be contacted from outside the detection device.
    FIG. 1 illustrates an example of a device 1 for detecting infrared radiation, as described in document EP2743659, the electrical connection pad 30 of which has a raised metal portion 31 with respect to the substrate 2.
    The detection device 1 comprises a plurality of thermal detectors 20 of which each absorbent membrane 21 is suspended above the substrate 2 at a non-zero distance H. Each absorbent membrane 21 is electrically connected to a portion 11a of the metal line of the reading circuit 10, the metal line here belonging to a penultimate level of electrical interconnection of a CMOS circuit.
    The detection device 1 also comprises a pad 30 of electrical connection of the reading circuit 10, which comprises a metal portion 31 raised above the substrate 2 and electrically connected to a second portion 11b of the metal line here belonging to the same level. electrical interconnection. The metal portion 31 is here elevated at the same distance H with respect to the substrate 2 as the absorbent membrane 21, and is connected to the reading circuit 10 by electrically conductive vias 32.
    A sacrificial layer is used during the production of the absorbent membrane 21 and the raised metal portion 31, and is then etched so as to suspend the absorbent membrane 21. A non-etched portion of the sacrificial layer may be present at the level of the pad. electrical connection 30, that is to say between the raised metal portion 31 and the substrate 2.
    SUMMARY OF THE INVENTION The object of the invention is to propose an electromagnetic radiation detection device comprising an electrical connection pad with raised metal portion having improved mechanical strength. For this purpose, the subject of the invention is an electromagnetic radiation detection device comprising: a reading circuit located in a substrate; - An electrical connection pad disposed on the substrate, comprising a metal portion, raised above the substrate and electrically connected to the read circuit.
    According to the invention, it comprises: - a protective wall extending under the raised metal portion so as to define therewith at least a portion of a cavity; - A layer portion, said reinforcement, located in the cavity, on which rests the raised metal portion.
    Some preferred but non-limiting aspects of this detection device are the following:
    The reinforcing portion may have a surface area greater than or equal to 25%, preferably 50% and more preferably 75%, of a so-called lower surface, oriented towards the substrate, of the raised metal portion.
    The protective wall may extend continuously to define a closed cavity.
    The protective wall may extend continuously to define a locally open cavity.
    The detection device may comprise at least one thermal detector, disposed on the substrate and electrically connected to the electrical connection pad by the read circuit, and comprising a membrane adapted to absorb the electromagnetic radiation to be detected and suspended above the substrate. a distance of the latter substantially equal to that separating the raised metal portion of the substrate.
    The protective wall may be made of an electrically conductive material, the latter electrically connecting the electrical connection pad to the reading circuit.
    The protective wall may surround at least one electrically conductive via electrically connecting the raised metal portion to an underlying portion of a metal line of the read circuit.
    The raised metal portion may have a lower surface, oriented towards the substrate, a dimension parallel to the substrate is greater than or equal to 2 times, preferably 10 times, and preferably 25 times, the distance separating said raised metal portion of the following substrate an axis substantially orthogonal to the substrate.
    The electrical connection pad may not substantially comprise a reinforcing portion outside said cavity. The invention also relates to a method for producing the detection device according to any one of the preceding characteristics, in which: - a sacrificial layer is deposited on an etch stop layer covering the substrate containing the read circuit; ; a protective wall is formed, through the sacrificial layer, so as to subsequently delimit at least a portion of a cavity; a raised metal portion is formed on the sacrificial layer, so that it rests on the protective wall and contributes to delimiting said cavity; at least part of the sacrificial layer is etched, a portion of the sacrificial layer, called the reinforcing portion, located in said cavity being not etched following this etching step.
    The sacrificial layer may be made of a mineral material, preferably a material based on a silicon oxide, and the etching step may be carried out by etching in an acid medium, preferably with hydrofluoric acid in phase steam.
    Concomitantly with the formation of the protective wall, it is possible to form anchoring pillars intended to ensure the mechanical retention of absorbent membranes of thermal detectors.
    BRIEF DESCRIPTION OF THE DRAWINGS Other aspects, objects, advantages and characteristics of the invention will appear better on reading the following detailed description of preferred embodiments thereof, given by way of non-limiting example, and made in reference to the accompanying drawings in which: Figure 2 is a schematic sectional view of a detection device according to one embodiment; Figure 3a is a schematic top view of the electrical connection pad of the detection device illustrated in Figure 2, and Figure 3b is a schematic top view of a variant of the electrical connection pad shown in Figure 3a; FIGS. 4a to 4g show the steps of a method of producing the detection device illustrated in FIG. 2; FIGS. 5a and 5b are schematic sectional views of variants of the detection device as illustrated in FIG. 2.
    DETAILED PRESENTATION OF PARTICULAR EMBODIMENTS
    In the figures and in the remainder of the description, the same references represent identical or similar elements. In addition, the various elements are not represented on the scale so as to favor the clarity of the figures.
    Figure 2 is a schematic cross-sectional view of a device 1 for detecting electromagnetic radiation according to a first embodiment.
    A three-dimensional orthonormal reference (Χ, Υ, Ζ) is defined here and for the rest of the description, in which the plane (X, Y) is substantially parallel to the plane of a substrate of the detection device 1, the Z axis being oriented in a direction substantially orthogonal to the plane of the substrate 2. Thus, the terms "vertical" and "vertically" extend as being relative to an orientation along the Z axis, and the terms "lower" and "higher" s' extend as relative to an increasing position when moving away from the substrate along the Z axis.
    In this example, the electromagnetic radiation detection device 1 is adapted to detect infrared or terahertz radiation. It comprises a matrix of thermal detectors 20 electrically connected to a reading circuit 10. FIG. 2 is a partial view of the detection device 1 and represents only a single thermal detector 20 disposed here in the vicinity of an electrical connection pad 30.
    The detection device 1 comprises a substrate 2, made of silicon, comprising an electronic reading circuit 10 made in CMOS technology making it possible to apply a control signal to the thermal detectors 10 and to read the detection signals generated by these sensors. in response to a detection of the electromagnetic radiation of interest.
    The reading circuit 10 may comprise a lower part (not shown) formed of electronic devices of MOS type, for example transistors, diodes, capacitors, adapted to the implementation of the various electronic functions of the read circuit. It further comprises several levels of electrical interconnections ensuring the electrical connections between the various MOS devices and the thermal detectors, as well as the electrical connection to at least one electrical connection pad of the reading circuit with the outside of the detection device.
    The reading circuit 10 thus comprises several levels of electrical interconnections each formed of a plurality of substantially planar metallic lines connected to the metal lines of the lower levels by electrically conductive vias, or vertical connections. The different levels of electrical interconnections are separated from each other by dielectric layers, called inter-metal dielectrics (or IMD, for Inter-Metal Dielectric, in English), these being traversed vertically by conductive vias. Each inter-metal dielectric layer may be made of an SiOx silicon oxide or a SiNx silicon nitride, or even a silicon oxide-based alloy having a low relative permittivity, such as SiOF, SiOC, SiOCH, etc ...
    In this example, the reading circuit 10 comprises a higher level of metal interconnection formed of a first portion 11a of a metal line, situated facing a thermal detector 20, and intended to be electrically connected to this detector 20, and a second portion 11b of metal line, located opposite an electrical connection pad 30, and intended to be electrically connected to this pad 30. The portions 11a, 11b of metal line of this level of metal interconnection are connected electrically to portions 13a, 13b of lower level wire line through conductive vias 12a, 12b. These portions 11a, 11b and the conductive vias 12a, 12b are electrically isolated from each other by an inter-metal dielectric layer 14.
    The substrate 2 further comprises an etch stop layer 5 which covers the surface formed by the metal line portions 11a, 11b and by the intermetal dielectric layer 14. This etch stop layer 5 is especially adapted to provide protection of the substrate 2 and the readout circuit 10 against a chemical etching, for example in an HF (hydrofluoric acid) acid medium, used to etch part of a sacrificial layer used during the production of the detection device. This etch stop layer 5 thus forms a hermetic and chemically inert layer providing protection for the inter-metal dielectric layers and underlying metal lines from chemical etching, and is electrically insulating to prevent any short circuit between the portions of the metal line. The etch stop layer 5 may be made of Al 2 O 3 alumina, or even nitride or aluminum fluoride. It may have a thickness of between a few tens and a few hundreds of nanometers, for example between 10 nm and 500 nm.
    On the substrate 2 here rests a thermal detector 20 comprising a portion 21 adapted to absorb the radiation to be detected. This absorbent portion 21 is thermally insulated from the substrate 2 and can be disposed at a so-called absorbent membrane suspended above the substrate 2 by holding and thermal insulation elements such as associated anchoring pillars 22 to heat-insulating arms (not shown). The anchor pillar 22 is electrically conductive and locally passes through the etch stop layer 5 to provide electrical contact with the portion 11a of the metal line. The absorbent membrane 21 is spaced from the substrate 2 by a distance H typically between 1pm and 5pm, for example about 2pm when the detectors are designed for the detection of infrared radiation of wavelength between 8pm and 14pm. By way of illustration, the thermal detector 20 may be a bolometer whose absorbent membrane 21 comprises a thermistor material whose electrical conductivity varies as a function of the heating of the membrane. However, any other type of thermal detector may be used, for example pyroelectric, ferroelectric or even thermopile detectors.
    On the substrate 2 also rests an electrical connection pad 30, intended to allow the electrical connection of the reading circuit 10 from the outside of the detection device 1, for example by means of a wire bonding (in English). , or even a tip contact during the test (pin probing) of the detection device. The electrical connection pad 30 comprises a metal portion 31 raised above the substrate 2 and electrically connected to the underlying portion 11b of the metal line of the reading circuit 10.
    The raised metal portion 31 has an upper face which forms a contact surface for the electrical connection, and an opposite lower face 33 oriented towards the substrate 2. The metal portion 31 is here raised above the substrate 2 at a distance substantially equal to the distance H of the absorbent membrane 21. More specifically, the lower face of the absorbent membrane 21 and the lower face 33 of the raised metal portion 31 are substantially coplanar and located at the same height H with respect to the Etch stop layer 5 of the substrate. The raised metal portion 31 may be the same or similar to that described in EP2743659. It can thus be formed of a stack of portions of layers of different metallic materials, for example a TiN titanium nitride portion covered with a portion of aluminum, itself optionally being covered with a TiN layer portion. .
    The electrical connection pad 30 comprises in this example a plurality of conductive vias 32 electrically connecting the raised metal portion 31 to the underlying portion 11b of the metal line of the reading circuit 10. The conductive vias 32 extend substantially vertical and contact on the one hand the raised metal portion 31 and on the other hand the portion 11b of metal line. Conductive vias 32 may be identical or similar to those described in EP2743659, and thus be formed of a TiN or TiW envelope surrounding the periphery of a copper or tungsten core. The envelope of TiN or TiW can provide tie layer and barrier layer functions with respect to the possible diffusion of copper. The conductive vias 32 may thus have a rod or column shape, of cross section in the substantially square plane (X, Y) having an area of, for example, between 0.25pm2 and 5pm2, and a height substantially equal to the distance H Advantageously, the anchoring pillars 22 of the thermal detector are substantially identical in terms of materials and dimensions to the conductive vias 32 of the electrical connection pad 30.
    The electrical connection pad 30 also comprises a protective wall 34, or several concentric walls 34, which extends (ent) continuously under the raised metal portion 31 so as to delimit, with the lower face 33 thereof, a cavity 3. By delimiting means that the protective wall 34 fixes at least a portion of the boundaries, in the plane (X, Y), of the cavity thus formed. The raised metal portion 31 rests on the protective wall 34 and thus delimits vertically, with the substrate 2, the cavity 3. This then has a height along the Z axis substantially equal to the height H, and a surface area in the plane (X, Y) whose perimeter is at least partly defined by the protective wall 34.
    The protective wall 34 extends along the Z axis between the substrate 2 and the raised metal portion 31 and then has a height substantially equal to the distance H. It extends longitudinally along a distance delimiting at least part of the edge of the cavity 3 in the plane (X, Y). Finally, it has a thickness, in the plane (X, Y), of the order of a few hundred nanometers to a few microns, for example of the order of 0.5pm. The protective wall 34 thus differs from the anchoring pillars 22 and conductive vias 32 in that it has a so-called longitudinal dimension, or length, greater than its thickness, for example 10 times, 100 times or even 2000 times greater than its thickness. It can be formed in a manner similar to the anchoring pillars 22 and the conductive vias 32. It can thus comprise a core, or core, of copper or tungsten interposed between two vertical layers of TiN or TiW.
    The electrical connection pad 30 also comprises a portion 4 of a layer of a reinforcing material located in the cavity 3 and defined by the protective wall 34. As will be described below, the reinforcing portion 4 is advantageously derived from a sacrificial layer used during the production of the absorbent membrane 21 and the raised metal portion 31. It can thus be formed of a mineral material, that is to say of a material allowing the realization of a layer inter-metal dielectric, capable of being etched for example by chemical etching with hydrofluoric acid (HF) in the vapor phase. As a purely illustrative example, this material may be an SiOx silicon oxide, or even an alloy based on silicon oxide possibly having a low relative permittivity, such as SiOF, SiOC, SiOCH, etc.
    The reinforcing portion 4 extends over the entire height of the cavity 3, so that the raised metal portion 31 rests at least partly on the reinforcing portion 4. It has a surface area in the plane (X, Y ), greater than or equal to 25% of the lower surface 33 of the raised metal portion 31. Preferably, this surface area of the reinforcing portion 4 is greater than or equal to 50%, more preferably greater than or equal to 75%, 80% or more, of the lower surface 33 of the raised metal portion 31. There is substantially no reinforcing portion 4 located outside the cavity 3 at the electrical connection pad 30, and preferably at the level of the thermal detectors 20. In this example, the conductive vias 32 are located in the cavity 3 and pass vertically through the reinforcing portion 4.
    Figure 3a is a top view of the electrical connection pad 30 illustrated in Figure 2. The electrical connection pad 30 here has a raised metal portion 31 of cross section in the plane (X, Y) substantially square. Other shapes are possible, for example rectangular or even polygonal, or circular or oval. Here it presents dimensions in the plane (X, Y) of the order of a few tens to a few hundred microns, for example 100 pm side.
    The protective wall 34 extends continuously below the raised metal portion 31, here along the circumferential edge thereof, so as to define, with the substrate 2 and more precisely with the etch stop layer 5, and with the lower face 33 of the raised metal portion 31, a cavity 3 here closed. The cavity 3 is said to be closed in the sense that the protective wall 34 forms a closed perimeter in the plane (X, Y). The closed cavity 3 is hermetically sealed against a chemical attack in HF acid medium as described below. In this example, the protective wall 34 here has a thickness of the order of 0.5 μm, a height along the Z axis of the order of 2 μm and delimits a cavity 3 of square surface of the order of 90 μm. side. It may comprise a copper or tungsten core interposed between two vertical layers opposite to each other and made based on an alloy or titanium compound.
    The closed cavity 3 is filled with a portion 4 of a layer of reinforcement material, which here completely fills the cavity 3. The reinforcing portion 4 thus extends throughout the volume of the cavity 3, so that the portion raised metal 31 rests at least partly on the reinforcing portion 4. The reinforcing portion 4 is here made of a layer of a mineral material, for example a silicon oxide.
    Several conductive vias 32, of a cross section in the plane (X, Y) of 0.25pm2, vertically cross the reinforcing portion 4 and thus contact the raised metal portion 31 and the underlying portion 11b of the metal line. They thus provide the electrical connection of the raised metal portion 31 to the reading circuit 10.
    Thus, the detection device 1 comprises an electrical connection pad 30 whose raised metal portion 31 has a strengthening of its mechanical strength, in that it rests on a reinforcing portion 4 located in the cavity 3 delimited by the wall It is indeed possible, by the arrangement of the protective wall 34 vis-à-vis the raised metal portion 31, to control the surface area of the reinforcing portion 4 so that it presents a sufficient extent to enhance the mechanical strength of the raised metal portion 31.
    Indeed, the inventors have observed that the electrical connection of the detection device 1 by contacting an electrical element, for example a wire, with the raised metal portion 31 can cause the application of a mechanical force on the electrical connection pad, in particular a shear force in the plane (X, Y), which can cause a displacement of the raised metal portion 31 likely to degrade the quality of electrical connection between the electrical connection pad 30 and the reading circuit 10.
    The inventors then demonstrated that the raised metal portion 31 of the electrical connection pad 30 has a reinforced mechanical strength when it rests on a portion 4 of reinforcing layer whose surface area is controlled and at least partially preserved from chemical etching by the protective wall 34. It is then possible to ensure a surface area of the reinforcing portion 4 such that it is greater than or equal to at least 25% of the lower surface of the raised metal portion, and preferably greater than or equal to at least 50%, even 75% or more. As described below, the layer portion 4 of the reinforcing material may be derived from the sacrificial layer used during the production of the absorbent membrane 21 and the raised metal portion 31.
    Figure 3b is a schematic top view of an electrical connection pad according to a variant of the connection pad illustrated in Figure 3a.
    The detection device is similar to that described with reference to Figure 2 and differs essentially in that the protective wall 34 extends continuously to define a cavity 3 open locally. By open cavity locally means a cavity having at least one opening 6 in the plane (X, Y). The protective wall 34 then does not form a closed perimeter. The opening 6 here has a height substantially equal to the distance H and a width in the (X, Y) plane such that, following an etching step by acid etching in a vapor phase HF medium, the portion of reinforcement 4 in the cavity 3 has a surface area, in the plane (X, Y), greater than or equal to 25%, or even greater than or equal to 50% and preferably greater than or equal to 75%, of the lower surface 33 of the raised metal portion 31. The width of the opening 6 is then determined prior to the formation of the protective wall 34, in particular according to an estimate of the etching rate of a sacrificial layer portion located under the portion raised metal 31 and in the absence of a protective wall 34, as described below.
    In this example, the protective wall 34 delimits a cavity 3 whose section in the plane (X, Y) has a rectangular surface shape 80pmx40pm. The protective wall 34 extends so that the cavity 3 has an opening 6 located here at one of the two sides of 40pm of the cavity. In the case of an acidic vapor phase HF attack of a sacrificial layer of silicon oxide, it has been observed that the etching rate under the raised metal portion 31 is greater, for example about 20 times greater, than the etching rate outside this raised metal portion 31. Thus, for illustrative purposes, the time required for etching a thickness of 2 pm of a sacrificial layer portion located outside the connection pad 30 leads to etching, under the raised metal portion 31, a sacrificial layer portion extending from the opening 6 along the X axis over a distance of 40pm. Thus, under the raised metal portion 31, a sacrificial layer portion with a surface area of 40 μm × 40 μm is removed by etching, and a so-called reinforcement portion 4 with a surface area of 40 μm × 40 μm is preserved. The raised metal portion 31 rests on the reinforcing portion 4 and its mechanical strength is then reinforced. Advantageously, the conductive vias 32 are located at the level of the reinforcing portion 4, and pass therethrough vertically. Alternatively or additionally, conductive vias 32 may be located in the area of the cavity 3 without a reinforcing portion 4.
    Figures 4a to 4g illustrate different steps of a method of producing the detection device according to the first embodiment. Several steps, apart from the step of forming the protective wall 34, may be similar or identical to that of the method described in EP2743659.
    With reference to FIG. 4a, a substrate 2 is made comprising a reading circuit 10 of the CMOS circuit type. The reading circuit 10 here comprises an electrical interconnection level comprising a first portion 11a and a second portion 11b of a metal line. The portions 11a, 11b are electrically connected to portions 13a, 13b of a metal line of a lower level of electrical interconnection by conductive vias 12a, 12b. The vias and metal lines are separated from each other by inter-metal dielectric layers. The substrate 2 here comprises an upper face at which the portions 11a, 11b of the metal line and the inter-metal dielectric layer 14 are exposed. This step of producing the substrate may be identical or similar to that described in the document EP2743659. Thus, by way of illustration, the conductive vias 12a, 12b and the portions 11a, 11b, 13a, 13b of metal lines may be made of copper or tungsten, by a damascene process in which trenches made with copper are filled with copper. inter-metal dielectric layer. The copper or tungsten may optionally be inserted transversely between vertical layers of titanium nitride, tantalum or other. The outcropping of the portions 11a, 11b of metal line at the upper face of the inter-metal dielectric layer 14 can be obtained by a chemical mechanical polishing (CMP) technique.
    With reference to FIG. 4b, an etching stop layer 5 is then deposited on the upper face of the substrate 2. The etch stop layer 5 thus continuously covers the inter-metal dielectric layer 14 as well as the portions 11a, 11b of metal line. It can be obtained, for example, by an Al2O3 alumina deposit made by ALD (for Atomic Rent Deposition, in English). Other materials may be suitable, such as aluminum nitride, aluminum trifluoride or even unintentionally doped amorphous silicon.
    With reference to FIG. 4c, a sacrificial layer 7 is deposited on the etch stop layer 7 in a material that is preferably mineral, for example made of silicon oxide deposited by PECVD (for Plasma Enhanced Chemical Vapor Deposition). It extends continuously over substantially the entire surface of the substrate 2 and covers the etch stop layer 5. The thickness along the Z axis of the sacrificial layer 7 subsequently defines the spacing distance H between the absorbent membrane 21 and the substrate 2, as well as between the raised metal portion 31 and the substrate 2. It depends in particular on the absorption properties of the thermal detectors that it is desired to obtain, and may be between 1pm and 5pm for the detection of radiation infrared, for example be equal to 2pm.
    With reference to FIG. 4d, vertical orifices 23, 35 are made for forming the anchoring pillars 22 of the thermal detector 20 on the one hand and the conductive vias 32 on the electrical connection pad 30 on the other hand. They are made by photolithography and etching, and pass through the sacrificial layer 7 and the etch stop layer 5 to open respectively to the first portion 11a and the second portion 11b of metal line. The vertical orifices 23, 35 may have a cross section in the plane (X, Y) of square shape and of surface substantially equal here to 0.25pm2.
    A trench 36 is also produced for the formation of the protective wall 34. The trench 36 is made by photolithography and etching, and passes through the sacrificial layer 7 until it ends here on the inter-metal dielectric layer 14. also, in this example, the etching stop layer 5. The trench 36 extends longitudinally in the plane (X, Y) so as to subsequently delimit the cavity 3. It has here a thickness, or width, in the plane (X, Y) of dimension substantially equal to 0.5pm. Preferably, the trench 36 is produced concomitantly, that is to say simultaneously, with the production of the vertical orifices 23, 35.
    With reference to FIG. 4e, anchoring pillars 22 and conductive vias 32 are then made in the vertical orifices 23, 35 as well as the protective wall 34 in the trench 36. The anchoring pillars 22 and the conductive vias 32 can be made identically in terms of dimensions and materials. They can be made by filling the orifices 23, 35 with one or more electrically conductive materials. For example, they may each comprise a layer of TiN deposited by MOCVD (for Metal Organic Chemical Vapor Deposition, in English) on the vertical sides of the orifices 23, 35, and a copper or tungsten core filling the space bounded transversely by the TiN layer. The protective wall 34 may be made concomitantly with the formation of the anchoring pillars 22 and the conductive vias 32, and in an identical manner in terms of materials. It can thus be formed by filling the trench 36 with a layer of TiN deposited by MOCVD on the vertical sides of the trench 36 and then with a copper or tungsten core filling the space delimited transversely by the TiN layer. A step of CMP then makes it possible to planarize the upper surface formed by the sacrificial layer 7, and by the conductive vias 32, the anchoring pillars 22 and the protective wall 34.
    With reference to FIG. 4f, the suspended diaphragm 21 and the raised metal portion 31 are produced. This step can be performed in the same manner or similar to that described in document EP2743659 and is not repeated in detail. Thus, the absorbent membrane 21 may comprise a first material adapted to absorb the electromagnetic radiation of interest and a second thermistor material, the electrical conductivity of which varies as a function of the heating of the membrane. The raised metal portion 31 comprises a portion of an electrically conductive material, for example aluminum, optionally interspersed along the Z axis between two portions of TiN. These conductive portions are conventionally produced by deposition, photolithography and etching. The raised metal portion 31 rests on the conductive vias 32 which provide the electrical connection with the read circuit 10. As an illustration, it may have a surface, in the plane (X, Y), of the order of 100 pmxlOOpm.
    With reference to FIG. 4g, the sacrificial layer 7 is partially etched so as to suspend the absorbent membrane 21. The etching can be carried out by chemical etching with hydrofluoric acid (HF) in the vapor phase. The chemical etching consumes substantially all the sacrificial layer 7 situated at the level of the thermal detector 20, thus making it possible to suspend the absorbent membrane 21 above the substrate 2. A reflective layer (not shown) is advantageously located at the level of the substrate 2. view of the absorbent membrane 21 so that the empty space forms a quarter-wave type optical cavity reinforcing the absorption of the radiation of interest by the thermal detector. At the level of the electrical connection pad 30, the chemical etching by vapor HF etches the sacrificial layer 7, with the exception of the sacrificial layer portion 4 located in the closed cavity 3 delimited by the protective wall 34. etched 4 of the sacrificial layer 7 thus forms the reinforcing portion 4 on which rests the raised metal portion 31, this reinforcing portion 4 reinforcing the mechanical strength of the raised metal portion 31.
    The inventors have found that a chemical etching of the sacrificial layer, in particular of a layer made of a silicon oxide by a HF acid in the vapor phase, has a first etching rate at the level of the thermal detectors, and has a second speed. etching, substantially greater than the first speed, for example 5 times greater, or even 10 times higher and more, when the sacrificial layer portion to be engraved is located below the raised metal portion. The inventors have thus observed that the etching rate by vapor HF etching increases sharply when the layer to be etched is located in a chamber delimited vertically between two surfaces opposite to each other, whose aspect ratio L / H is greater than or equal to 2, L being a transverse dimension of the enclosure in the (X, Y) plane and H being the height of the enclosure along the Z axis.
    In this example, the enclosure delimited vertically by the substrate and the raised metal portion has a dimension L in the plane (X, Y) of the order of 100 pm over a height H along the Z axis of the order of 2 pm . The etching of the sacrificial layer portion in this chamber is then nearly 20 times faster than the etching of the same sacrificial layer outside this enclosure.
    Indeed, it appears that the products of the chemical etching reaction of the sacrificial layer, for example water when the sacrificial layer is made of silicon oxide, can not be discharged freely because of a confining effect in the speaker with high aspect ratio L / H. The products then seem to act as catalysts for etching and substantially increase the speed of etching in the enclosure.
    Thus, in the absence of a protective wall 34, as in the example described in document EP2743659 relating to the prior art, a large part of the sacrificial layer situated under the raised metal portion can be etched, which can lead to the raised metal portion to rest on a sacrificial layer portion of too small surface area, resulting in a decrease in its mechanical strength.
    According to the invention, the presence of the protective wall 34 delimits a cavity 3, all or part of the sacrificial layer portion therein is preserved from the chemical etching. The surface area of the non-etched portion is thereby controlled, thus forming a reinforcing portion 4 ensuring a better mechanical strength of the raised metal portion 31.
    In the example of Figure 3a, the cavity 3 is closed and substantially hermetic vis-à-vis the chemical etching HF vapor. Thus, the portion of sacrificial layer located in the cavity 3 is substantially not etched by etching, and then forms a portion 4 of large reinforcement on which rests the raised metal portion 31. The mechanical strength of this portion 31 is then substantially improved.
    Figure 5a is a schematic sectional view of a detection device 1 according to an alternative embodiment.
    The detection device 1 is similar to that described with reference to Figure 2 and differs essentially in that the protective wall 34 is in mechanical and electrical contact with the portion 11b of metal line. The protective wall 34, being advantageously electrically conductive, also provides a function of electrical connection between the raised metal portion 31 and the portion 11b of the metal line of the reading circuit 10. The electrical connection is then improved. Furthermore, the portions 11a and 11b of metal lines also provide an etch stop layer function during the formation of the orifices 23, 35 and the trench 36 through the sacrificial layer 7.
    The size of the portion 11b of metal line can then be adapted so that the protective wall 34 delimits a cavity 3 whose surface area in the plane (X, Y) is greater than or equal to 25%, 50%, 75 % or more of the lower surface 33 of the raised metal portion 31.
    Figure 5b is a schematic sectional view of a detection device 1 according to another embodiment.
    The detection device 1 is similar to that described with reference to FIG. 5a and differs essentially in that the electrical connection pad 30 does not include conductive vias 32, so that the raised metal portion 31 is electrically connected. to the portion 11b of metal line only by the protective wall 34, the latter being electrically conductive. The portion 11b of metal line then has a shape, in the plane (X, Y), adapted so that the protective wall 34 is in direct contact with it.
    Specific embodiments have just been described. Various variations and modifications will occur to those skilled in the art.
    Thus, as an alternative to the embodiment illustrated in FIG. 2, in which the protective wall is in contact, at its lower part, with the inter-metal dielectric layer underlying the etch stop layer, the protective wall may rest on the etch stop layer, and possibly on support pads resting on the etch stop layer, as described in EP2840370.
    权利要求:
    Claims (12)
    [1" id="c-fr-0001]
    A device (1) for detecting electromagnetic radiation, comprising: - a read circuit (10) located in a substrate (2); - an electrical connection pad (30) disposed on the substrate (2), comprising a metal portion (31), raised above the substrate (2) and electrically connected to the read circuit (10); characterized in that it comprises: - a protective wall (34) extending under the raised metal portion (31) so as to define therewith at least a portion of a cavity (3); - A portion (4) of so-called reinforcing layer, located in the cavity (3), on which rests the raised metal portion (31).
    [2" id="c-fr-0002]
    2. Detection device (1) according to claim 1, wherein the reinforcing portion (4) has a surface area greater than or equal to 25%, preferably 50% and more preferably 75%, of a so-called lower surface area. (33), facing the substrate (2), of the raised metal portion (31).
    [3" id="c-fr-0003]
    3. Detection device (1) according to claim 1 or 2, wherein the protective wall (34) extends continuously to define a cavity (3) closed.
    [4" id="c-fr-0004]
    4. Detection device (1) according to claim 1 or 2, wherein the protective wall (34) extends continuously so as to define a cavity (3) open locally.
    [5" id="c-fr-0005]
    5. Detection device (1) according to any one of claims 1 to 4, comprising at least one thermal detector (20) disposed on the substrate (2) and electrically connected to the electrical connection pad (30) by the circuit for reading (10), and comprising a membrane (21) adapted to absorb the electromagnetic radiation to be detected and suspended above the substrate (2) at a distance from the latter substantially equal to that separating the raised metal portion (31) from the substrate (2).
    [6" id="c-fr-0006]
    6. Detection device (1) according to any one of claims 1 to 5, wherein the protective wall (34) is made of an electrically conductive material, the latter electrically connecting the electrical connection pad (30) to reading circuit (10).
    [7" id="c-fr-0007]
    7. Detection device (1) according to any one of claims 1 to 6, wherein the protective wall (34) surrounds at least one electrically conductive via (32) electrically connecting the raised metal portion (31) to a portion underlying (11b) a metal line of the read circuit (10).
    [8" id="c-fr-0008]
    8. Detection device (1) according to any one of claims 1 to 7, wherein the raised metal portion (31) has a lower surface (33) facing the substrate (2), a dimension parallel to the substrate is greater than or equal to 2 times, preferably 10 times, and preferably 25 times, the distance separating said raised metal portion (31) from the substrate (2) along an axis substantially orthogonal to the substrate (2).
    [9" id="c-fr-0009]
    9. Detection device (1) according to any one of claims 1 to 8, wherein the electrical connection pad (30) has substantially no reinforcing portion (4) out of said cavity (3).
    [10" id="c-fr-0010]
    10. A method of producing the detection device (1) according to any one of the preceding claims, wherein: - is deposited on an etch stop layer (5) covering the substrate (2) containing the read circuit (10), a sacrificial layer (7); forming, through the sacrificial layer (7), a protective wall (34) arranged to subsequently delimit at least a portion of a cavity (3); a raised metal portion (31) is formed on the sacrificial layer (7) so that it rests on the protective wall (34) and contributes to delimiting said cavity (3); at least part of the sacrificial layer (7) is etched, a portion (4) of the sacrificial layer, referred to as the reinforcing portion, located in said cavity (3) being not etched following this etching step.
    [11" id="c-fr-0011]
    11. The method of claim 10, wherein the sacrificial layer (7) is made of a mineral material, preferably a material based on a silicon oxide, and in that the etching step is carried out by etching. chemical in an acidic medium, preferably with hydrofluoric acid in the vapor phase.
    [12" id="c-fr-0012]
    12. A method according to claim 11 or 12, in which, concomitantly with the formation of the protective wall (34), anchoring pillars (22) are formed for the mechanical maintenance of absorbent membranes (21). thermal detectors (20).
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    同族专利:
    公开号 | 公开日
    US10060797B2|2018-08-28|
    CN107121203B|2021-01-12|
    EP3211390A1|2017-08-30|
    CN107121203A|2017-09-01|
    US20170241840A1|2017-08-24|
    FR3048125B1|2020-06-05|
    EP3211390B1|2022-01-26|
    KR20170099783A|2017-09-01|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    EP2743659A1|2012-12-17|2014-06-18|Commissariat à l'Énergie Atomique et aux Énergies Alternatives|Method for manufacturing an infrared detection device|
    DE69732862T2|1997-12-18|2006-04-13|Mitsubishi Denki K.K.|SEMICONDUCTOR ARRANGEMENT FOR RECORDING INFRARED PICTURES|
    FR2875298B1|2004-09-16|2007-03-02|Commissariat Energie Atomique|THERMAL DETECTOR FOR ELECTROMAGNETIC RADIATION COMPRISING AN ABSORBENT MEMBRANE FIXED IN SUSPENSION|
    EP2021749B1|2006-05-25|2013-01-23|Panasonic Corporation|Infrared sensor|
    FR2906029B1|2006-09-18|2010-09-24|Ulis|ELECTRONIC DETECTION DEVICE AND SENSOR COMPRISING SUCH A DEVICE|
    CN102280455B|2011-05-11|2013-01-09|武汉高德红外股份有限公司|Non-refrigeration infrared focal plane array seeker|
    CN103575407A|2012-07-18|2014-02-12|北京大学|Terahertz radiation detector|
    FR3009865B1|2013-08-22|2015-07-31|Commissariat Energie Atomique|BOLOMETRIC DETECTOR WITH REINFORCED THERMALIZATION COMPENSATION BOLOMETER|CN106124067B|2016-07-18|2019-01-18|上海集成电路研发中心有限公司|Infrared acquisition pixel structure and preparation method thereof, mixing image device|
    WO2018018709A1|2016-07-28|2018-02-01|上海集成电路研发中心有限公司|Infrared detector pixel structure and preparation method therefor|
    JP6552547B2|2017-05-24|2019-07-31|三菱電機株式会社|Infrared sensor and infrared solid-state imaging device|
    FR3099248B1|2019-07-26|2021-08-06|Commissariat Energie Atomique|Umbrella absorber bolometer, component comprising such a bolometer and method of manufacturing such a bolometer|
    FR3113127A1|2020-07-29|2022-02-04|Lynred|METHOD FOR MAKING AN INFRARED IMAGING MICRO-BOLOMETER AND ASSOCIATED MICRO-BOLOMETER|
    法律状态:
    2017-02-28| PLFP| Fee payment|Year of fee payment: 2 |
    2017-08-25| PLSC| Publication of the preliminary search report|Effective date: 20170825 |
    2018-02-26| PLFP| Fee payment|Year of fee payment: 3 |
    2019-02-28| PLFP| Fee payment|Year of fee payment: 4 |
    2020-02-28| PLFP| Fee payment|Year of fee payment: 5 |
    2021-02-26| PLFP| Fee payment|Year of fee payment: 6 |
    优先权:
    申请号 | 申请日 | 专利标题
    FR1651511|2016-02-24|
    FR1651511A|FR3048125B1|2016-02-24|2016-02-24|ELECTROMAGNETIC RADIATION DETECTION DEVICE WITH RAISED ELECTRICAL CONNECTION PLOT|FR1651511A| FR3048125B1|2016-02-24|2016-02-24|ELECTROMAGNETIC RADIATION DETECTION DEVICE WITH RAISED ELECTRICAL CONNECTION PLOT|
    KR1020170024357A| KR20170099783A|2016-02-24|2017-02-23|Deivce for detecting electromagnetic radiation comprising a raised electrical connection pad|
    EP17157579.8A| EP3211390B1|2016-02-24|2017-02-23|Device for the detection of electromagnetic radiation with overhead electrical connection pad|
    US15/441,719| US10060797B2|2016-02-24|2017-02-24|Device for detecting electromagnetic radiation comprising a raised electrical connection pad|
    CN201710102672.7A| CN107121203B|2016-02-24|2017-02-24|Device for detecting electromagnetic radiation comprising a raised electrical connection pad|
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