• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    For joining two substrates (1, 2) by molecular adhesion, they are brought into contact with each other in a first step (1) to form a unit (3) with a connection interface (4), and in a second step ( b) the adhesion of the unit (3) is increased above a threshold above which water can no longer diffuse via the connection interface; in a step (c) of the waterless treatment, the substrates (1, 2) are heated in an atmosphere having a dew point temperature below -10 ° C; and controlling the dew point of the atmosphere to which the substrates (1, 2) are subjected from the waterless treatment from the step (c) to the end of the second step to limit or prevent the occurrence of sticking defects at the joint interface ,
    公开号:AT516576A2
    申请号:T51014/2015
    申请日:2015-11-27
    公开日:2016-06-15
    发明作者:
    申请人:Soitec Silicon On Insulator；Commissariat Energie Atomique；
    IPC主号:
    专利说明:

    The invention relates to a method for bonding two substrates by molecular adhesion.
    Direct wafer bonding is a well-known technique found in applications in the fields of microelectronics, optoelectronics, and electromechanical microsystems, for example, for the manufacture of silicon substrates on insulating materials. Photovoltaic cells with multiple connections or for the development of 3D structures.
    According to this technique, two substrates are brought into close contact so that their surfaces approach each other sufficiently to produce an atomic and / or molecular bond (hydroxyl or covalent bond). The presence of water at the interface facilitates the preparation of these compounds. Thus, adhesive forces are brought into contact between the two surfaces without using an intermediate adhesive layer, such as an adhesive layer or a polymer.
    The resulting compound is then generally subjected to a thermal treatment; In this case, the temperature may vary between 50 ° C and 1200 ° C, depending on the nature of the substrates and the intended application to strengthen the adhesion.
    In some cases, the molecular adhesion bonding entails the occurrence of defects in the bonding surface, referred to as a bonding defect. These may be "voucher" type defects. Defects in bonds can lead to trapping and accumulation of gaseous areas between the surfaces of the substrates being brought together. These surfaces can correspond to the adsorbed surfaces on the surface of the substrates in their preparation before assembly, they can chemical residues
    Reactions correspond, in particular the chemical reaction with water, which arise during the contact of the substrates or during the curing of the adhesive reinforcement. A description of the chemical phenomena that develop during the assembly by molecular adhesion, for example, in the article "Hydrophilic low-temperature direct wafer bonding" of C.
    Ventosa et al, Journal of Applied Physics 104, 123534 (2008) or in the article "A review of hydrophilic silicon wafer bonding" by V. Masteika et al, ECS Journal of Solid State Science and Technology, 3 (4) Q42-Q54 ( 2014).
    Existing defects in the bonding of interfaces are detrimental to the quality of the structure produced. For example, if the merging step is followed by a phase of intangling of one of the two substrates to form a layer, by grinding or Smart Cut ™ technology, a lack of adhesion between two surfaces at the level of a tackiness failure may be localized Peel off the layer at this point. In the case of integration of 3D components, a bonding defect prevents the production of the electrical contact of the components formed on one or the other substrate, and this makes these components inoperable.
    A solution for the reduction of assembly errors and in particular of adhesive defects is proposed in US2013 / 0139946 A, which describes a mounting method by molecular adhesion including the gas circulation on the substrate surfaces before their assembly.
    This method makes it possible to eliminate water molecules desorbed from the surfaces by gas flow circulation outside the bonding area. This method allows, according to this document, while the water saturation of the atmosphere of
    Range and to maintain quality at all mounts.
    However, the application of this method is very sensitive and may, for example, by the nature of the combined substrates and after the reinforcing treatment to an insufficient adhesion between the substrates or lead to existing residual defects of the bond. It should be noted, in particular, that gas flow is an important vector for particle contamination for which, in particular, molecular adhesion is very susceptible, which particles can cause sticking defects.
    An object of the invention is therefore to provide a robust method to reduce or even completely prevent the number of gluing errors in the combination of two substrates and the molecular adhesion. Another object of the invention is to ensure a sufficient degree of adhesion between the merged substrates.
    In order to implement at least one of the objects, the invention proposes a method of bringing together two substrates by molecular adhesion, comprising: a first step of contacting the first and second substrates to form a unit with a connection interface, and a second step strengthening the degree of adhesion of the unit above a threshold of adhesion above which water is no longer able to spread over the length of the connection interface, characterized by - a step of waterless treatment of the first and second substrates in a treatment atmosphere a dew point below -10 ° C; and controlling the dew point in an operating atmosphere exposed to the first and second substrates from the non-water processing step to the second step to limit or prevent the occurrence of adhesion defects at the connection interface.
    Thus, by controlling the dew point, the dissipation of water from the atmosphere surrounding the unit at the connection interface is prevented and the occurrence or prevention of sticking defects prevented.
    According to further advantageous, non-limiting properties of the invention, taken individually or taken together, the following should be mentioned:
    The control of the dew point of the operating atmosphere is to maintain the temperature of the dew point above -10 ° C for at least 10 minutes from the step of waterless treatment and to the end of the second step.
    The control of the dew point of the operating atmosphere is to maintain the temperature of the dew point below -10 ° C from the step of waterless treatment and to the end of the second step.
    The operating atmosphere is the ambient atmosphere in which the process is carried out.
    The waterless treatment step is carried out in a containment vessel at operating atmosphere.
    The second step involves thermally firing the unit at a temperature between 50 ° C and 1200 ° C.
    The temperature of firing is above 300 ° C.
    The burning takes place in a neutral firing atmosphere.
    The processing atmosphere is static.
    The processing atmosphere has atmospheric
    Print.
    The contacting step is performed at the ambient temperature.
    The method includes a step of preparing the hydrophilic surface of the first and second substrates.
    The method comprises a step of incorporating the unit between the waterless treatment step and the second step.
    The waterless treatment step is carried out simultaneously with the contacting step.
    The waterless treatment step has a duration of at least 30 seconds prior to contacting the first and second substrates.
    The waterless treatment step is carried out after the contacting step.
    The step of contacting takes place in an atmosphere with a dew point of over -10 °.
    The waterless treatment step is carried out at a temperature between 20 ° C and 150 ° C.
    The first or the second substrate is made of silicon and the temperature of the waterless treatment of the step is between 40 ° C and 60 ° C.
    The step of waterless treatment lasts between 1 hour and 100 days.
    The invention will be further explained with reference to embodiments shown in the drawing. In detail, in the drawing:
    Fig. 1 is an illustration of an acoustic microscope photograph of one of the connection interface of two silicon substrates, one of which is provided with a silicon oxide layer having a thickness of 10 nm;
    Figures 2a and 2b are illustrations of acoustic micrographs of a connection interface of two pairs of substrates stored for 5 days and 60 days, respectively, stored for 5 and 60 days in a humid environment;
    Fig. 3 is an illustration of an acoustic microscope photograph of the connection interface of two pairs of substrates stored for 20 days in a waterless environment;
    FIG. 4 is a graph showing the distance of the water from the connection interface above the storage temperature: FIG.
    Fig. 5 in the sub-figures c), a) and b) an embodiment of the invention;
    Fig. 6 in the sub-figures a) / c) and b) a variant of this embodiment of the invention; and
    Fig. 7 in the partial figures a), c) and b), a further embodiment of the invention.
    An unused silicon substrate was bonded to another silicon substrate with a fine silicon oxide layer having a thickness of 10 nm. The contacting of the substrates was carried out in a clean room atmosphere, with a standard relative humidity of 50% (corresponds to a dew point of 9 ° C); followed by a step of strengthening the adhesion of the two interconnected substrates, which was carried out by the intermediate step of firing at 550 ° C for 2 hours.
    This contacting is particularly susceptible to the occurrence of tacky defects, especially due to the fine layer of silica at the interface.
    After this sequence of steps, the contact interface was viewed through an acoustic microscope. Fig. 1 shows the result of this observation: the black areas of the contact area correspond to glueing errors, i. the contact areas where no adhesion occurred and which may be filled with gas. From Fig. 1, as well as from Figs. 2a, 2b and 3, the contour of the unit formed from the two substrates can be seen.
    Subsequently, two further test series were carried out.
    In the first series, two units were formed by contacting identical substrates, resulting in the results of FIG. At the end of the contacting, both units were stored in a humid atmosphere (dewpoint below -10 ° C) for 5 days to 60 days. At the end of these storage times, each of the bond-strengthening units was subjected to firing at 550 ° C for 2 hours, and then the contact interfaces were examined by the acoustic microscope. The results obtained are shown in FIGS. 2a and 2b. It can be seen here that - compared to Fig. 1 - the storage in a humid atmosphere between the contacting and the treatment for bonding reinforcement leads to a net increase in the number of adhesive defects and their density. It can also be seen that this increase in the bonding errors increases with the duration of the storage, as a result of the spread of the edges of the substrates in the direction of their center.
    In the second part series, a unit was formed by contacting identical substrates; this resulted in the results of Figure 1. At the end of the contacting, the unit was stored in a waterless atmosphere with a moisture content below 10 ppm (dewpoint <-63 ° C) for 20 days. At the end of this period, this unit was also fired at 550 ° C for 2 hours for curing.
    Fig. 3 shows the results in an acoustical microscope image of the interface of contacting this unit after firing. From Fig. 3, it can be seen in a comparison with Fig. 1, that the storage in a waterless atmosphere to reduce the number of
    Sticking error leads, especially at the edges of the unit.
    It thus follows from these experiments, and contrary to the general assumption, that after the substrates have been contacted, water is still able to diffuse between the bonding interface and the atmosphere surrounding the assembly. Thus, a relatively humid environment results in a return of water from the edges of the unit, which diffuses toward the center of the unit over time. Conversely, a relatively dry atmosphere causes water to spill over the edges of the unit.
    Complementary investigations have made it possible to analyze this phenomenon more precisely. As a result, the leakage of water from the contact interface is promoted by a relatively dry environment and is also sensitive to the temperature to which it is exposed.
    Fig. 4 shows a graphic representation of this phenomenon. The ordinate axis indicates the dimension (in mm) of the entire ring area, which will remain flawless after 300 hours of storage of the unit without water, which was also fired similarly to the previous examples. This dimension can be equal to the distance of diffusion of water at the contact interface during storage. The abscissa axis of Fig. 4 indicates the storage temperature (in ° C).
    It can be observed that this distance has a maximum around a storage temperature of 50 ° C. The increase in the adhesion energy caused by exposure of the unit to storage temperature counteracts the mobility of the water and tends to severely limit the length of diffusion at elevated storage temperature.
    Of course, the results shown in Fig. 4 are also dependent on the particular conditions of the experiment, e.g. the surface treatment preceding the contacting, the thickness of the silicon oxide formed on one of the substrate surfaces, etc., but they are representative of the phenomena of diffusion given at the contact interface according to the storage temperature. In particular, the maximum of the length of the diffusion, at 50 ° C, according to Figure 4, move. In any case, there is a threshold of the degree of adhesion of the unit above which one can assume that the water is no longer able to diffuse at the contact interface of the contacting. Thus, it can be assumed that if at least one of the substrates 1, 2 (see Fig. 5) is made of silicon, this threshold is reached when the temperature during firing is above 300 ° C.
    The invention utilizes the demonstrated phenomena detected by the tests to develop molecular adhesion bonding, which is particularly advantageous and the detailed description of which follows.
    As is known per se, according to FIGS. 5 to 7, this connection method comprises a first step a) of contacting a first substrate 1 and a second substrate 2 to form a unit 3 with a connection or contact interface 4. Preferably, for simplicity of implementation, this first step a) is carried out at ambient temperature (i.e., between 10 ° C and 30 ° C). One or the other of the substrates 1, 2 may be made of any material, but it is of particular interest if at least one of the substrates 1, 2 consists of a material or contains a material that reacts chemically with water. As explained above, this chemical reaction can be the cause of glue defects that develop at the contact interface of the two substrates.
    This is particularly the case with semiconductor materials such as silicon, germanium, silicon carbide, InP, AsGa, and metals such as copper, titanium, tungsten, aluminum and nickel.
    This is also the case when a material that reacts chemically with water is under another material that does not chemically react with water (such as silica or amorphous alumina), but that can be traversed by water underlying material can react.
    Prior to step a) of contacting, both substrates 1, 2 have received hydrophilic surface treatments, such as cleaning, activation by plasma or grinding. The one and / or the other of the substrates 1, 2 may be provided with an intermediate layer, such as oxide or silicon nitride.
    The contacting procedure also includes a second step of increasing the degree of adhesion of the unit 3 over an adhesion threshold above which water is no longer able to diffuse via the connection interface.
    The second step b) of the reinforcement may comprise or correspond to a thermal treatment, in particular a firing, for example between a temperature of 50 ° C and 1200 ° C, and the duration of which may extend over a few seconds or several hours. The burning takes place in a neutral atmosphere.
    The exact adhesion threshold at which water is no longer able to spread appreciably to the bonding interface may vary depending on the nature of the bonded materials, as well as the degree of humidity of the atmosphere around the unit. However, it can be assumed that if at least one of the substrates 1, 2 is made of silicon, this threshold is reached when the temperature of firing is above 300 ° C. The skilled artisan may easily set the value of this threshold for other materials, for example, based on similar experiments as mentioned above.
    Furthermore, the bonding method also comprises a step c) of the waterless treatment of the first substrate 1 and the second substrate 2 in a treatment atmosphere having a dew point of below -10 ° C. This step c) precedes the aforesaid step b) of increasing the degree of adhesion.
    As can be remembered, the temperature of the dew point is defined as the lowest temperature at which gas can flow without liquid water forming through saturation. It is a traditional and reliable measurement of the moisture content of gas.
    The waterless treatment is therefore carried out in a particularly dry atmosphere, which makes it possible to limit or reduce the amount of water at the connection interface. Thus, the dew point of the waterless treatment below -10 ° C or below -50 ° C or even below -85 ° C can be selected.
    In order to limit the development of tackiness defects and thus achieve a satisfactory degree of adhesion, it is also provided that the dew point of the operating atmosphere to which the two substrates 1, 2 are exposed, from step c) of the waterless treatment and to the end of the second Step b) of the increase in the degree of adhesion is controlled.
    Under control, it is understood that the dew point is kept sufficiently low during the period between the end of step c) of the waterless treatment and the following step b) of increasing the adhesion to prevent water from the treatment atmosphere distributed over the connection interface and thus leads to Klebefehlern or to their development. At the same time, this dew-point atmosphere can be adjusted so that the contact interface has sufficient water to develop a sufficient degree of adhesion between the two substrates 1, 2. The nature of this control is detailed for each mode of reacting the compound of the substrates, as described below.
    A first type of connection production is shown in FIG. The step c) of the waterless treatment is preceded by the first step a) of bringing the two substrates 1, 2 into contact, or it is carried out simultaneously with the latter.
    This can be done in different ways. For example, the treatment atmosphere may be the ambient atmosphere in which the contacting process occurs (generally in a clean room). This atmosphere is maintained at a dew point temperature below -10 ° C. Thus, the entirety of the steps and the treatments that constitute the process, and more particularly, the step a) of contacting in a particularly dry atmosphere, wherein a controlled amount of water is obtained on the surface of the substrates and the binding interface.
    In the field of microelectronics and the joining of substrates, it is common to provide a relative humidity of the working environment of 30% to 50% (this corresponds to a dew point temperature between 3 ° C and 9 ° C). However, there are areas such as the field of manufacturing batteries in which the working atmosphere has a dew point temperature of usually below -10 ° C. This mode of carrying out the waterless treatment may result in the need for relatively important means, but has the advantage of equally controlling the dew point temperature of the working atmosphere from step c) of the waterless treatment and to the end of the second step b) of the adhesion enhancement is guaranteed.
    In this case, the control of the dew point temperature of the working atmosphere is to keep the unit 3 in the atmosphere of the working space at a dew point temperature of below -10 ° C, and this applies to the entire process duration. Depending on the sequence of steps in the present process, this duration may be 1 hour or even 100 days.
    According to a second mode of application of step c) shown in Fig. 6, the waterless treatment is carried out simultaneously with the first step a) of contacting. The steps c) and a) can also be carried out in a security container 5 in a treatment atmosphere. The containment 5 may be a chamber with contacting means in which the step a) of contacting is carried out.
    The container 5 or the chamber is therefore maintained by suitable means at a dew point temperature of below -10 ° C. This may be, for example, a unit or unit 6 for the purification of gas, which enters the container 5 or the chamber. The gas which forms the treatment atmosphere circulates before entering the container 5 or in the chamber in the cleaning system 6 via a molecular sieve 7, for example made of copper, which is filled with water from the atmosphere to produce a particularly dry gas , and its dew point temperature can be controlled.
    When the first substrate 1 and the second substrate 2 are placed in the containment 5 and in the chamber, respectively, they are exposed to the protective atmosphere having a dew point temperature below -10 ° C; according to step c) of the waterless treatment in the present process.
    Preferably, and for simplicity of implementation, the safety atmosphere of the waterless treatment has atmospheric pressure. In addition, the safety atmosphere may be static, i. that this atmosphere does not circulate in the form of a stream in the chamber. Thus, the substrate surfaces are prevented from becoming contaminated prior to contacting with particles.
    Advantageously, the surfaces of the substrates are exposed to the protective atmosphere of the waterless treatment for at least 30 seconds prior to contacting the substrates. This ensures that the amount of water at the interface of these substrates 1, 2 is in the desired equilibrium. For the same reason, it is possible to heat the safety atmosphere of the waterless treatment, for example to between 20 ° C and 150 ° C. The contacting step may be performed in the same protection environment.
    At the end of these steps, irrespective of the way they are used in step c) of the waterless treatment in the first mode of implementation, the unit 3 formed by contacting the first substrate 1 and the second substrate 2 is provided, and the one controlled
    Has amount of water at the interface of the contact 4.
    As already mentioned above, this first step a) is followed by step b) of increasing the degree of adhesion of the unit 3 to above a threshold of adhesion above which water is no longer able to diffuse to the connection interface 4.
    In order to obtain the reduced amount of water at the connection interface 4 at a level which limits the occurrence or development of sticking defects, the dew point temperature of the working atmosphere to which the unit 3 is exposed is controlled between these two steps.
    As already mentioned, this control is carried out when the atmosphere of the room in which the process takes place is kept at a dew point temperature of, for example, below -10 ° C.
    As an alternative and in particular if step c) of the waterless treatment is carried out inside a containment vessel 5, s. 6, the bonding is performed so that the unit 3 is not exposed to an atmosphere having a dew point temperature above -10 ° C for longer than 10 minutes. In other words, the control of the dew point of the operating atmosphere is to maintain the temperature of the dew point at a temperature above -10 ° C for at least 10 minutes from step c) of the waterless treatment and until the end of the second step b) of the adhesion reinforcement ,
    It has been found that when the substrates 1, 2 are exposed to a dew point temperature in excess of -10 ° C for a maximum of 10 minutes, the diffusion of water to the interface interface is limited and the quality of the
    Connection can be obtained, especially as regards detention errors.
    This can be achieved by performing the method for which the beginning of the second step b) is implemented within less than 10 minutes after removal of the unit 3 from the containment 5.
    According to a preferred embodiment, step b) corresponds to a burning process, and the gas which forms in the firing atmosphere has a dew point temperature below -10 ° C. This ensures that during the first few seconds of this bonding-strengthening firing, even though the degree of adhesion has not yet reached the threshold, the water present in the fuel gas can not diffuse to the contact interface.
    If the gas circulating in the kiln is not dry (ie having a dew point temperature above -10 ° C), it is ensured that the duration of the exposure between the end of the waterless treatment step c) and the beginning of the second step, accumulated during the duration of firing, which is necessary to reach the threshold of adhesion, well below 10 minutes.
    In the event that it is not possible to systematically perform step c) of the waterless treatment and the second step b) within less than 10 minutes in succession, it is envisaged to temporarily store the unit 3 in an area such as a drying oven has a dew point of less than -10 ° C. This intermediate storage can be of any duration, for example from 1 hour to 100 days or more, without the risk of excess water entering the connection interface and compromising the quality of the connection.
    This intermediate storage may also be carried out in an atmosphere having a dew point temperature of less than -10 ° C, such as -30 ° C or -80 ° C, optionally at a temperature of, for example, 20 ° C to 150 ° C. These provisions make it possible to further improve the quality of the connection.
    According to another embodiment, cf. 7, the step c) of the waterless treatment after the first step a) of the contacting of the two substrates 1, 2 is carried out.
    The fact that the water is able to diffuse outward from the contact interface 4 of the unit 3 in order to control the amount of water at this interface 4 is used.
    In this case, the first step a) of the contacting may take place in an atmosphere with a dew point temperature above -10 ° C. Thus, it is not necessary to carry out this step a) in a safety environment, such as in a chamber, and / or to equip the connection equipment with a cleaning system. This is thus particularly advantageous.
    In addition, much of the contacting process may take place in any atmosphere, provided that step c) of the waterless treatment takes place prior to the second step b), and that the working atmosphere between step c) of the waterless treatment and the end of the waterless treatment second step b) is controlled.
    Thus, the unit 3 can be stored arbitrarily long in any atmosphere between the first step a) of the contacting and the step c) of the waterless treatment.
    In this embodiment, the unit 3, which consists of the connection of the two substrates 1 and 2 at the end of the first
    Step a), water in an uncontrolled amount at its connection interface 4 on.
    In order to improve the quality of the connection, in particular with regard to bonding errors, the unit 3 is subjected to a waterless treatment in the course of step c), at a dew point temperature of below -10 ° C, for example -30 ° C or even -80 ° C.
    Preferably, this treatment is carried out in a drying oven, which makes it possible to heat the unit 3 to between 20 ° C and 150 ° C in order to promote the diffusion of water, in particular from the connection interface 4 to the outside.
    As in the embodiment described above, and to ensure a dew point temperature below -10 ° C, the drying oven can be connected to a purification plant for its atmosphere, allowing a dry gas to circulate in the vessel, having a dew point temperature below -10 ° C C has.
    The duration of the waterless treatment can be adapted to the conditions. If, for example, one wishes to have all excess water distributed at the connection interface 4 (over the entire surface of the contact), this duration is thus adapted to the dimension of the substrates 1, 2.
    Also, the duration of this waterless treatment for circular substrates 1, 2 of silicon, when the unit 3 is heated to 50 ° C and exposed to a dew point temperature of -50 ° C during this treatment, is determined by the following table:
    The experimental values given above correspond to average values and can be adjusted, in particular according to the amount of water present at the connection interface 4 before the waterless treatment.
    It may not be necessary to try to distribute the water over the entire connection interface 4, and diffusion over a reduced peripheral distance may be sufficient. In this case, the duration of the waterless treatment as shown in the above table can be shortened.
    The second step b) of increasing the degree of adhesion of the bonding process is performed subsequent to the step c) of the waterless treatment. According to a preferred embodiment, the gas has a dew point temperature of below -10 ° C. during firing. This ensures that during the first few seconds of this bond-strengthening firing, even though the adhesion energy has not yet reached the threshold, the water present in the fuel gas can not spread excessively on the contact interface.
    As in the first embodiment, the working atmosphere exposed to the unit 3 between the waterless treatment step c) and the second step b) is controlled. The same means as used in the first
    Embodiment have been described, are also applicable to this second embodiment and therefore need not be described again.
    example 1
    Two silicon substrates <001> with a diameter of 200 mm and a resistance p between 1 and 50 ohm / cm are mixed with an ozone-added water solution, with 40 mg / 1 ozone, with an APM solution (ammonium peroxide mixture) with a concentration of ammonia, oxygenated water and deionized water of 0.25 / 1/5 respectively. Subsequently, both plates are dried and placed in a connecting chamber, in which an ambient temperature and a nitrogen atmosphere with a dew point temperature below -85 ° C prevails. After waiting for 1 minute, both surfaces are connected and the unit is removed from the chamber. At least 10 minutes later, the unit is placed in a tube furnace under nitrogen, with a nitrogen content of the water of at least 100 ppb (-90 ° C dew point temperature). Regardless of the temperature of the firing, which takes place at between 50 ° C and 1200 ° C, the adhesive bond has no gluing errors. In addition, the degree of adhesion between both substrates is sufficient to proceed with a mechanical dilution of either substrate.
    Example 2
    Two substrates identical to those of Example 1 are prepared, also identical to this Example 1. After drying, the two substrates are temporarily bonded together at ambient temperature. Subsequently, the unit formed by these two bonded substrates is placed in a clean room having air with a dew point temperature below -40 ° C, or in a container with
    Nitrogen atmosphere and a dew point temperature below -85 ° C. The two substrates are released from each other and their surfaces are exposed to this waterless atmosphere.
    After waiting for 1 minute, the two substrates are connected together at ambient temperature and leave the clean room or container. At least 10 minutes later, the unit is placed in a tube furnace under nitrogen, with a nitrogen content of the water of at least 100 ppb (-90 ° C dew point temperature). Before the temperature rises, it stays in this atmosphere for 10 minutes. Regardless of the temperature of the firing, which then takes place at a temperature between 50 ° C and 1200 ° C, the adhesive bond has no gluing errors. In addition, the degree of adhesion between both substrates is sufficient to proceed with the mechanical thinning of one of the two substrates.
    Example 3
    In a clean room containing air with a dew point temperature below -40 °, two silicon substrates <001> of 200 mm diameter, a resistance p between 1 and 50 ohm / cm are cleaned the same as in Example 1. After drying, both substrates are bonded together at ambient temperature. Without leaving the dry clean room, the resulting unit is placed in a tube furnace under nitrogen, with a nitrogen content of the water of at least 100 ppb (-9 ° C dew point temperature). Before the temperature rises, it stays in this atmosphere for 10 minutes. Regardless of the temperature of the firing, which then takes place at a temperature between 20 ° C and 120 ° C, the adhesive bond has no gluing errors. In addition, the degree of adhesion between both substrates is sufficient to proceed with the mechanical thinning of one of the two substrates.
    Example 4
    Two substrates identical to those of Example 1 are also prepared identically as in this example. After drying, both substrates are bonded together. Subsequently, the substrates are dissolved in a clean room containing air with a dew point temperature below -40 ° C from each other and exposed for 1 minute to the atmosphere of this clean room. They are then reconnected at ambient temperature. Without leaving the dry clean room, the unit formed from the two interconnected substrates is placed in a tube furnace under nitrogen with a nitrogen content of the water of at least 100 ppb (-90 ° C dew point temperature). Before the temperature rises, it stays in this atmosphere for 10 minutes. Regardless of the temperature of the firing, which then takes place at a temperature between 20 ° C and 1200 ° C, the adhesive bond has no gluing errors. In addition, the degree of adhesion between both substrates is sufficient to proceed with the mechanical thinning of one of the two substrates.
    Example 5
    Two 200 mm diameter silicon substrates <001>, similar to the previous examples and identically prepared as in the previous examples, are bonded together in a gluing plant which has no containment. They are connected in an atmosphere with a standard dew point temperature of 9 ° C (corresponding to a relative humidity of 50%) and at ambient temperature. The bonded substrates are then placed in a drying cabinet in which neutral nitrogen gas is circulated at a temperature of 50 ° C; the neutral gas has a dew point temperature of -80 ° C; the unit remains here for 43 days. The adhesive bonding unit is then placed directly in a tube furnace with nitrogen having less than 100 ppb of water (dew point -90 ° C). Regardless of the temperature of the firing, which is then carried out at a temperature between 300 ° C and 1200 ° C, the adhesive bond after this thermal treatment has no gluing errors. In addition, the degree of adhesion between the two substrates is sufficient to proceed with mechanical thinning of either substrate.
    Example 6
    Silicon substrates <001> with a diameter of 200 mm are prepared identically as in the previous example. The bonded substrates are then placed in a dry cabinet in which neutral nitrogen gas is circulated at a temperature of 50 ° C; the neutral gas has a dew point temperature of -80 ° C; the unit remains here for 43 days. At the end of this period, firing is carried out directly in the storage drying cabinet, thus without transferring the plates to a tube furnace. As in the previous examples, the adhesive bond at the end of this firing process has no gluing errors. In addition, the degree of adhesion between the two substrates is sufficient to proceed with the mechanical thinning of one of the two substrates.
    The invention is not limited to the described embodiments, and modifications and modifications are possible without departing from the scope of the invention.
    The invention is of particular interest to all compounds of substrates in which a large number of tacky defects are presently observed, such as the bonding of substrates with a very thin insulating interlayer (smaller than 50 nanometers), the direct bonding of heterogeneous III-V materials for the purpose of creating compounds (such as the compounds of a photovoltaic cell), the combination of substrates which have undergone intensive surface activation (such as plasma activation or mechanical chemical polishing).
    The invention is also of interest in joining substrates which typically do not result in tacky defects except in a region located at the edge of the plates. This configuration may be attributed to an accumulation of water at this location due to the spread of an adhesive wave, as described, for example, in WO2013 / 160841A. The invention, and in particular the intermediate storage in a waterless environment, in this case make it possible to prevent this accumulation of water and to avoid the errors that can consequently form there.
    Although examples of silicon wafers have been cited in the above description for ease of procurement and experimentation, the invention is by no means limited to these materials. In addition, one or the other substrate, a coating of the surface, which serves as an insulating material, have. One or the other of the substrates may contain microelectronic components or simple plots of a metallic compound. Although the step b) of enhancing the adhesion can be made simply by the intermediate step of firing, as explained above, other treatments (especially thermal) can be implemented for this reinforcement. For example, treatment with microwaves or lasers is possible.
    The contacting may be followed by a step of thinning one of the two substrates 1, 2 by abrasion, grinding or chemical etching. This can also be a separation of a
    Part of one of the two substrates 1, 2 along a fragile plane formed before the connection, for example according to the technology Smart Cut ™.
    权利要求:
    Claims (15)
    [1]
    PATENTAN'S PRIDE
    A method of joining two substrates by molecular adhesion, comprising a first step (1) of contacting the first and second substrates (2) to form a unit (3) having a connection interface (4) and a second one Step (b) of increasing the degree of adhesion of the unit (3) over a threshold of adhesion above which water is no longer able to spread over the length of the connection interface (4), characterized by: a step ( c) waterless processing of the first and second substrates (1,2) in a treatment atmosphere having a dew point below -10 ° C; and controlling the dew point in an operating atmosphere exposed to the first and second substrates (1, 2) from the processing step (c) without water and to the end of the second step (b) to prevent the occurrence of adhesion defects at the joint Interface to limit or prevent.
    [2]
    2. The method according to claim 1, characterized in that in the control of the dew point of the operating atmosphere, the temperature of the dew point to above -10 ° C for at least 10 minutes from step (c) of the waterless treatment and to the end of the second step (b). is maintained.
    [3]
    3. The method according to claim 1 or 2, characterized in that in the control of the dew point of the operating atmosphere, the temperature of the dew point to below -10 ° C from step (c) of the waterless treatment and maintained until the end of the second step (b) becomes.
    [4]
    4. The method according to any one of claims 1 to 3, characterized in that the second step comprises a thermal firing of the unit (3) at a temperature between 50 ° C and 1200 ° C.
    [5]
    5. The method according to any one of claims 1 to 4, characterized in that the atmosphere of the treatment is static.
    [6]
    6. The method according to any one of claims 1 to 5, characterized in that the atmosphere is under atmospheric pressure.
    [7]
    7. The method according to any one of claims 1 to 6, characterized in that the step (a) of the contacting is carried out at ambient temperature.
    [8]
    8. The method according to any one of claims 1 to 7, characterized by a previous step for preparing the hydrophilic surface of the first and the second substrate (1, 2).
    [9]
    9. The method according to any one of claims 1 to 8, characterized by a step of intermediate storage of the unit (3) between the step (c) of the waterless treatment and the second step (b).
    [10]
    10. The method according to any one of claims 1 to 9, characterized in that the step (c) of the waterless processing precedes the first step (a) of the contacting or is carried out simultaneously with this.
    [11]
    11. The method according to any one of claims 1 to 10, characterized in that the waterless treatment has a duration of at least 30 seconds before contacting the first and the second substrate (1, 2).
    [12]
    12. The method according to any one of claims 1 to 9, characterized in that the step (c) of the waterless treatment after the first step (a) of the contacting is carried out.
    [13]
    13. The method according to any one of claims 1 to 12, characterized in that the first step (a) of the contacting takes place in an atmosphere with a dew point of -10 °.
    [14]
    14. The method according to claim 12 or 13, characterized in that the step (c) of the waterless treatment at a temperature of between 20 ° C and 150 ° C is performed.
    [15]
    15. The method according to any one of claims 1 to 14, characterized in that the first or the second substrate (1, 2) consists of silicon and the temperature of the waterless treatment of step (c) is between 40 ° C and 60 ° C.
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    同族专利:
    公开号 | 公开日
    DE102015223347A1|2016-06-02|
    KR20160064011A|2016-06-07|
    FR3029352B1|2017-01-06|
    AT516576A3|2017-11-15|
    AT516576B1|2019-11-15|
    CN105655243A|2016-06-08|
    US9718261B2|2017-08-01|
    JP6643873B2|2020-02-12|
    CN105655243B|2020-05-15|
    FR3029352A1|2016-06-03|
    US20160152017A1|2016-06-02|
    JP2016103637A|2016-06-02|
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    FR2980916B1|2011-10-03|2014-03-28|Soitec Silicon On Insulator|PROCESS FOR PRODUCING A SILICON TYPE STRUCTURE ON INSULATION|
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    FR2990054B1|2012-04-27|2014-05-02|Commissariat Energie Atomique|METHOD FOR BONDING IN A GAS ATMOSPHERE HAVING A NEGATIVE JOULE-THOMSON COEFFICIENT|
    US8796054B2|2012-05-31|2014-08-05|Corning Incorporated|Gallium nitride to silicon direct wafer bonding|
    FR3000092B1|2012-12-26|2015-01-16|Commissariat Energie Atomique|CHLORINATED PLASMA SURFACE TREATMENT IN A BONDING PROCESS|WO2017086462A1|2015-11-19|2017-05-26|ブランテック株式会社|Ice making device, moving body, flake ice production device, and flake ice production method|
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    CN111640814A|2020-06-05|2020-09-08|天津三安光电有限公司|Solar cell structure and preparation method thereof|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    FR1461544A|FR3029352B1|2014-11-27|2014-11-27|METHOD FOR ASSEMBLING TWO SUBSTRATES|
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