• 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:
    A vertical double diffuses MOSFET includes a nitride film (26) formed on a gate electrode (18). An ion implant window (34) is formed through the nitride film. P-type ions are implanted through the ion implant window into the semiconductor substrate (12), and the implanted ions are diffused to thereby form a main diffusion region (14). At the same time, the oxide film is grown inside the ion implant window to form a thick walled portion (36). Ions of the p-type are implanted through, as a mask, the thick walled portion, gate electrode and nitride film into semiconductor substrate, and thermally diffused thus forming a channel diffusion region (22). Further, n-type ions are implanted through the same mask and then thermally diffused to provide source diffusion regions.
    公开号:US20010000113A1
    申请号:US09/728,990
    申请日:2000-12-04
    公开日:2001-04-05
    发明作者:Takayuki Kito
    申请人:Takayuki Kito；
    IPC主号:H01L29-7802
    专利说明:
    [1] 1. 1. Field of the Invention
    [2] 2. This invention relates to a vertical double diffused MOSFET and method for manufacturing same, and more particularly to a vertical double diffused MOSFET manufactured through a self-aligned process which is applicable for switching power sources, AC adapters, battery chargers, motor control circuits, inverter illumination, DC/DC converters or the like, and a method for manufacturing such a device.
    [3] 3. 2. Description of the Prior Art
    [4] 4. There is shown in FIG. 3 a conventional vertical double diffused MOSFET of the kind as above. The MOSFET 1 includes a semiconductor substrate 2 having a main body 2 a and an epitaxial layer 2 b. The semiconductor substrate 2 has a main diffusion region 3 a formed in a surface thereof. The semiconductor substrate 2 has, on the surface, a gate electrode 5 having at least one window 5 a formed through an oxide film 4. The semiconductor substrate 2 is formed, at its bottom surface, with a drain electrode 6. Also, in the surface of the semiconductor substrate 2, a channel diffusion region 3 b and source diffusion region 3 c is formed in relation to the gate electrode 5 at a peripheral edge of the window 5 a. On the gate electrode 5 an insulation layer 7 is formed of oxide silicon containing phosphorus (PSG). Over the insulation layer 7, a metal interconnect layer (source electrode) 8 is formed connecting to a source diffusion region 3 c.
    [5] 5. In manufacturing a vertical double diffused MOSFET 1, an n-type epitaxial layer 2 b and oxide film 9 a is formed on an n-type semiconductor substrate (main body) 2 a, as shown in FIG. 4A. The oxide film 9 a at one part is removed by etching to form a window 9 b. Through this window 9 b boron (B) ions are implanted to the surface of the semiconductor substrate 2. After etch-removing oxide film 9 a, the boron (B) ions are thermally diffused to thereby provide a main diffusion region 3 a. Simultaneous with this, a not-shown thermal oxide film is formed. As shown in FIG. 4B, this thermal oxide film is etched under a predetermined condition into an oxide film 4 having a thick walled portion 9 c. Subsequently, as shown in FIG. 4C a gate electrode 5 is formed on the oxide film 4, and part of the gate electrode is etched to thereby provide a window 5 a. Then, boron (B) ions are implanted through, as a mask, the gate electrode 5 into the surface of the semiconductor substrate 2. The implanted boron ions are thermally diffused to form a channel diffusion region 3 b. Further, phosphorus (P) ions are implanted through, as a mask, the gate electrode 5 and thick walled portion 9 c to the surface of the semiconductor substrate 2. The implanted phosphorus ions are then thermally diffused to provide a source diffusion 3 c. Then an insulation layer 7 is formed over the oxide film 4 and gate electrode 5, as shown in FIG. 4E. Subsequently, as shown in FIG. 4F, the insulation layer 7 and oxide film 4 is partly etched away to form a contact hole 9 d. Thereafter, a metal interconnect layer 8 is formed on the insulation layer 7 in a manner of connected to the source diffusion region 3 c, as shown in FIG. 3. Further, a drain electrode 6 is formed at the underside of the semiconductor substrate 2.
    [6] 6. In the prior art, however, the insulation layer 7 has used silicon oxide containing phosphorus (PSG). Therefore, it has been impossible to completely block contaminants, such as mobile ions, from intruding into the electrode 5 during the manufacture process or in an operational environment after manufacture. Due to this, there has been a problem that the gate electrode 5 deteriorate in electric characteristic (threshold voltage, etc) due to aging.
    [7] 7. On the other hand, the thick walled portion 9 c was formed in a separate process (FIG. 4B) from the process of forming the main diffusion region 3 a (FIG. 4A), making the manufacture process complicate. Moreover, there existed a fear that misalighnment might occur in each of the processes. If a misalighnment be caused in the process of forming the thick walled portion 9 c, the source diffusion regions 3 c on left and right of the thick walled portion 9 c were formed into different widths from each other. Thus, there has been a fear of causing variation in electric current amount to be supplied to these source diffusion regions 3 c from the metal interconnect layer 8. SUMMARY OF THE INVENTION
    [8] 8. Therefore, it is a primary object of the present invention to provide a vertical double diffused MOSFET which is capable of preventing the gate electrode from deteriorating in its characteristic, and a method for manufacturing such a device.
    [9] 9. It is another object of the present invention to provide a method for manufacturing a vertical double diffused MOSFET wherein the process that might lead to misalignment is eliminated thus stabilizing product quality.
    [10] 10. A vertical double diffused MOSFET according to the present invention is characterized in that a nitride film is used as an insulation layer interposed between a gate electrode and a metal interconnect layer.
    [11] 11. That is, a vertical double diffused MOSFET, comprises: a semiconductor substrate; an oxide film formed on the semiconductor substrate; a gate electrode formed on the oxide film and having at least one window; a nitride film formed on the oxide film and the gate electrode; an ion implant window formed through the nitride film at a center of the window, ions of a first conductivity type being implanted through the ion implant window to the semiconductor substrate and thermally diffused thereby forming a main diffusion region; a thick walled portion formed by growing the oxide film in the ion implant window, wherein ions of the first conductivity type are implanted through as a mask the gate electrode and the nitride film on the gate electrode into the semiconductor substrate and thermally diffused to form a channel diffusion region, and ions of a second conductivity type being implanted through as a mask the thick walled portion, the gate electrode and the nitride film on the gate electrode into the semiconductor substrate and thermally diffused thereby forming a source diffusion region.
    [12] 12. A method for manufacturing a vertical double diffused MOSFET according to the present invention, comprises the steps of: (a) forming an oxide film on a substrate; (b) forming a gate electrode having at least one window on the oxide film; (c) forming a nitride film as an insulation layer on the oxide film and the gate electrode; (d) forming an ion implant window through the nitride film at a center of the window; (e) implanting ions of a first conductivity type through the ion implant window to the substrate; (f) thermally diffusing the ions to form a main diffusion region and growing the oxide film inside the ion implant window to form a thick walled portion; (g) implanting ions of the first conductivity type through as a mask the thick walled portion, the gate electrode and the nitride film on the gate electrode to the substrate and thermally diffused to form a channel diffusion region; and (h) implanting ions of a second conductivity type through a mask of the thick walled portion, the gate electrode and the nitride film on the gate electrode to the substrate and thermally diffused to form a source diffusion region.
    [13] 13. In the vertical double diffused MOSFET according to the present invention, the nitride film interposed between the gate electrode and the metal interconnect layer has a dense film texture. This nitride film serves to physically shield contaminants from entering into the gate electrode. Consequently, the gate electrode is prevented from deteriorating in characteristic due to contaminants.
    [14] 14. Furthermore, in the manufacture method, the main diffusion region and the thick walled portion are simultaneously formed in the step (f). This reduces the number of processes leading to misalignment as compared to the prior art of FIG. 4 wherein these formations are carried out by different processes. Also, the ions implanted through the ion implant window to the semiconductor substrate are thermally diffused to provide a main diffusion region, simultaneous with which a thick walled portion is formed inside the ion implant window by thermal oxidation. Thus, the thick walled portion is accurately formed at a center of the main diffusion region. It is therefore possible to simplify the manufacture process and stabilize the MOSFET quality.
    [15] 15. The above described objects and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS
    [16] 16.FIG. 1 is an illustrative view showing an embodiment of the present invention;
    [17] 17.FIG. 2A-FIG. 2I are sectional views showing a process for the FIG. 1 embodiment;
    [18] 18.FIG. 3 is an illustrative view showing a conventional vertical double diffused MOSFET; and
    [19] 19.FIG. 4A-FIG. 4F are sectional views showing a process for the conventional vertical double diffused MOSFET. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
    [20] 20. Referring to FIG. 1, there is illustrated a vertical double diffused MOSFET 10 of this embodiment, which includes a semiconductor substrate 12 having an n-type main body 12 a and an n-type epitaxial layer 12 b. The semiconductor substrate 12 has a main diffusion region 14 formed in a first conductivity type (e.g. “p-type”) in a surface thereof. The semiconductor substrate 12 has, on the surface, a gate electrode 18 having at least one window 18 a formed through a gate dielectric film 16. The semiconductor substrate 12 also has a drain electrode 20 formed on an underside of the semiconductor substrate 12. In the surface of the semiconductor substrate 12 are formed a p-type channel diffusion region 22 in association with the gate electrode at an periphery of the window 18 a as well as a source diffusion region 24 in a second conductivity type (e.g. “n-type”). A nitride film (insulation layer) 26 is formed of silicon nitride (SiN) or the like on the gate electrode 18. On the nitride film, a metal interconnect layer (source electrode) 30 is formed connecting to a source diffusion region 24 through a contact hole 28. The nitride film 26 has a texture that is by far denser than a film texture of the conventional insulation layer (PSG) 7, as was shown in FIG. 3. Thus the nitride film 26 serves as a protection film to physically shield contaminants (movable ions, etc.) from intruding into the gate electrode 18.
    [21] 21. It will be noted that FIG. 1 illustrates a minimum unit constituting a MOSFET 10. In actual, however, such structures are horizontally continuously formed in an array form wherein the gate electrode 18 is provided for all the device cells. That is, the illustrated MOSFET 10 is so-called a single gate MOSFET, and considered separately from a so-called dual gate MOSFET.
    [22] 22. Explanation is made below on a method for manufacturing a vertical double diffused MOSFET 10 with reference to FIG. 2A-FIG. 2I. First, an n-type epitaxial layer 12 b is formed on an n-type silicon (Si) main body 12 a, as shown in FIG. 2A. On the epitaxial layer, an oxide film (SiO2) 16 is formed to a thickness of approximately 300-1000 Å by a thermal oxidation technique. Further, a polysilicon (poly-Si) film 32 is formed to a thickness of approximately 4000-11000 Å on the oxide film by a CVD technique. By implanting a predetermined concentration of phosphorus (P) ions into the polysilicon film 32, a gate electrode 18 is formed. Subsequently, as shown in FIG. 2B the gate electrode 18 is masked by not-shown resist to perform etching, thereby forming a window 18 a. Then, a nitride film 26 is formed to a thickness of approximately 3000-8000 Å over the gate electrode 18 and oxide film 16, by the CVD technique as shown in FIG. 2C. The nitride film 26 is etched at a center of the window 18 a to thereby form a ion-implant window 34 having a width of approximately 4-25 μm. Through this ion-implant window 34, boron (B) ions are implanted under a predetermined condition (e.g., acceleration energy: 50-150 KeV, dosage: 1×1014−5×1015 atoms/cm2) into the surface of the semiconductor substrate 12.
    [23] 23. Then, the boron (B) ions are thermally diffused to provide a main diffusion region 14 with a depth of approximately 3-8 μm, as shown in FIG. 2D. Further, the oxide film 16 at a portion exposed by the ion implant winder 34 is thermally grown into a thick walled portion 36 having a thickness of approximately 2500-6500 Å. Subsequently, boron (B) ions are implanted through, as a mask, the thick walled portion 36, the gate electrode 18 and the nitride film 26 on the gate electrode 18 into the surface of the semiconductor substrate 12 as shown in FIG. 2E, under a predetermined condition (e.g., acceleration energy: 50-150 KeV, dosage: 1×1013−8×1013 atoms/cm2). As shown in FIG. 2F, the boron (B) ions are thermally diffused to form channel diffusion region 22 having a depth of approximately 2-5 μm.
    [24] 24. Then, as shown in FIG. 2G phosphorus (P) ions are implanted into the surface of the semiconductor substrate 12 through, as a mask, the thick walled portion 36, gate electrode 18 and the nitride film 26 on the gate electrode 18, under a predetermined condition (e.g. acceleration energy: 100-200 KeV, dosage: 1×1015−1×1016 atoms/cm2). The phosphorus (P) ions are thermally diffused to thereby form source diffusion regions 24 with depth of approximately 1-2 μm, as shown in FIG. 2H. Subsequently, a contact hole 28 is formed through the nitride film 26 and oxide film 16 thereby exposing at its bottom the source diffusion regions 24, as shown in FIG. 2I.
    [25] 25. Thereafter, an aluminum-based metal is spattered over the nitride film 26 to provide metal interconnect film 30 connected to the source diffusion region 24, as shown in FIG. 1. Further, a drain electrode 20 is formed of an aluminum-based metal by sputter on the underside of the semiconductor substrate 12.
    [26] 26. In the MOSFET 10 of this embodiment, the nitride film 26 with a dense film texture positively prevents contaminants (movable ions, etc.) from intruding into the gate electrode 18. Thus the gate electrode 18 is prevented from deteriorating in characteristic. Meanwhile, there is no intervening process between the gate electrode 18 forming process (FIG. 2B) and nitride film 26 forming process. Accordingly, there is no fear that contaminants intrude into the gate electrode during the manufacture process.
    [27] 27. Furthermore, the main diffusion region 14 and the thick walled portion 36 are substantially simultaneously formed in the common heating process (FIG. 2D). This can reduce the number of processes in which misalignment might occur, as compared to the prior art having different processes. It is therefore possible to simplify the manufacture process and stabilize the product quality.
    [28] 28. In the above embodiment, the gate electrode 18 used polysilicon (poly-Si). Alternatively, tungsten silicide (WSi) for titanium silicide (TiSi) may be employed. Further, in the above embodiment, the n-type semiconductor elements may be made by a p-type semiconductor and the p-type semiconductor elements by an n-type semiconductor.
    [29] 29. Although the present invention has been described and illustrated in detail, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, the spirit and scope of the present invention being limited only by the terms of the appended claims.
    权利要求:
    Claims (5)
    [1" id="US-20010000113-A1-CLM-00001] 1. In a vertical double diffused MOSFET, said vertical double diffused MOSFET characterized in that a nitride film is used as an insulation layer interposed between a gate electrode and a metal interconnect layer.
    [2" id="US-20010000113-A1-CLM-00002] 2. A vertical double diffused MOSFET, comprising:
    a semiconductor substrate;
    an oxide film formed on said semiconductor substrate;
    a gate electrode formed on said oxide film and having at least one window;
    a nitride film formed on said oxide film and said gate electrode;
    an ion implant window formed through said nitride film at a center of said window, ions of a first conductivity type being implanted through said ion implant window to said semiconductor substrate and thermally diffused thereby forming a main diffusion region;
    a thick walled portion formed by growing said oxide film in said ion implant window, wherein ions of the first conductivity type are implanted through as a mask said gate electrode and said nitride film on said gate electrode into said semiconductor substrate and thermally diffused to form a channel diffusion region, and ions of a second conductivity type being implanted through as a mask said thick walled portion, said gate electrode and said nitride film on said gate electrode into said semiconductor substrate and thermally diffused thereby forming a source diffusion region.
    [3" id="US-20010000113-A1-CLM-00003] 3. A vertical double diffused MOSFET according to
    claim 2 , wherein said main diffusion region and said thick walled portion are substantially simultaneously formed in one heating process.
    [4" id="US-20010000113-A1-CLM-00004] 4. A method for manufacturing a vertical double diffused MOSFET, comprising the steps of:
    (a) forming an oxide film on a substrate;
    (b) forming a gate electrode having at least one window on said oxide film;
    (c) forming a nitride film as an insulation layer on said oxide film and said gate electrode;
    (d) forming an ion implant window through said nitride film at a center of said window;
    (e) implanting ions of a first conductivity type through said ion implant window to said substrate;
    (f) thermally diffusing said ions to form a main diffusion region and growing said oxide film inside said ion implant window to form a thick walled portion;
    (g) implanting ions of the first conductivity type through as a mask said thick walled portion, said gate electrode and said nitride film on said gate electrode to said substrate and thermally diffused to form a channel diffusion region; and
    (h) implanting ions of a second conductivity type through a mask of said thick walled portion, said gate electrode and said nitride film on said gate electrode to said substrate and thermally diffused to form a source diffusion region.
    [5" id="US-20010000113-A1-CLM-00005] 5. A manufacturing method according to
    claim 4 , wherein said step (f) is substantially one heating step.
    类似技术:
    公开号 | 公开日 | 专利标题
    US6287906B1|2001-09-11|Semiconductor device having MOS transistor and method of manufacturing the same
    US5578508A|1996-11-26|Vertical power MOSFET and process of fabricating the same
    US5472894A|1995-12-05|Method of fabricating lightly doped drain transistor device
    US7288470B2|2007-10-30|Semiconductor device comprising buried channel region and method for manufacturing the same
    US5371024A|1994-12-06|Semiconductor device and process for manufacturing the same
    US5714393A|1998-02-03|Diode-connected semiconductor device and method of manufacture
    US20040094802A1|2004-05-20|Semiconductor device and method of forming the same
    US7449403B2|2008-11-11|Method for manufacturing semiconductor device
    US20060289904A1|2006-12-28|Semiconductor device and method of manufacturing the same
    US6800528B2|2004-10-05|Method of fabricating LDMOS semiconductor devices
    US6596598B1|2003-07-22|T-shaped gate device and method for making
    JP2002016080A|2002-01-18|Manufacturing method of trench-gate type mosfet
    US5747371A|1998-05-05|Method of manufacturing vertical MOSFET
    US7824987B2|2010-11-02|Method of manufacturing a semiconductor device including a SRAM section and a logic circuit section
    US6229178B1|2001-05-08|Vertical double diffused MOSFET and method for manufacturing same
    US5600177A|1997-02-04|Semiconductor device having an electrically conductive layer including a polycrystalline layer containing an impurity and a metallic silicide layer
    US6426533B2|2002-07-30|Semiconductor device and manufacturing method thereof
    US6110786A|2000-08-29|Semiconductor device having elevated gate electrode and elevated active regions and method of manufacture thereof
    JP3166911B2|2001-05-14|Method for manufacturing semiconductor device
    KR100273320B1|2001-01-15|Silicide Formation Method of Semiconductor Device_
    US6936517B2|2005-08-30|Method for fabricating transistor of semiconductor device
    KR20000004527A|2000-01-25|Method for forming contacts of semiconductor devices
    KR0151039B1|1998-12-01|Semiconductor device with polycide interconnection constructure
    EP0355691A2|1990-02-28|Semiconductor device and process for producing the same
    KR100855283B1|2008-09-01|method for fabricating capacitor
    同族专利:
    公开号 | 公开日
    DE19922802A1|1999-11-25|
    US6229178B1|2001-05-08|
    US6376311B2|2002-04-23|
    JPH11330090A|1999-11-30|
    JP3464382B2|2003-11-10|
    DE19922802B4|2006-04-13|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    CN105706221A|2013-11-08|2016-06-22|住友电气工业株式会社|Silicon carbide semiconductor device and method for producing same|US4443931A|1982-06-28|1984-04-24|General Electric Company|Method of fabricating a semiconductor device with a base region having a deep portion|
    JPS62162361A|1986-01-13|1987-07-18|Nissan Motor Co Ltd|Vertical mos transistor|
    US4798810A|1986-03-10|1989-01-17|Siliconix Incorporated|Method for manufacturing a power MOS transistor|
    US4716126A|1986-06-05|1987-12-29|Siliconix Incorporated|Fabrication of double diffused metal oxide semiconductor transistor|
    FR2605800B1|1986-10-24|1989-01-13|Thomson Semiconducteurs|METHOD FOR MANUFACTURING A MOS COMPONENT|
    JP2600301B2|1988-06-28|1997-04-16|三菱電機株式会社|Semiconductor memory device and method of manufacturing the same|
    JP3156300B2|1991-10-07|2001-04-16|株式会社デンソー|Vertical semiconductor device|
    KR0143459B1|1995-05-22|1998-07-01|한민구|Morse-gate type power transistor|
    JP3464382B2|1998-05-18|2003-11-10|ローム株式会社|Manufacturing method of vertical double diffusion MOSFET|JP3464382B2|1998-05-18|2003-11-10|ローム株式会社|Manufacturing method of vertical double diffusion MOSFET|
    US6983940B2|2003-07-29|2006-01-10|American Seal And Engineering Company, Inc.|Metallic seal|
    US7518196B2|2005-02-23|2009-04-14|Intel Corporation|Field effect transistor with narrow bandgap source and drain regions and method of fabrication|
    法律状态:
    2002-04-04| STCF| Information on status: patent grant|Free format text: PATENTED CASE |
    2005-09-30| FPAY| Fee payment|Year of fee payment: 4 |
    2009-09-23| FPAY| Fee payment|Year of fee payment: 8 |
    2013-09-25| FPAY| Fee payment|Year of fee payment: 12 |
    优先权:
    申请号 | 申请日 | 专利标题
    JP13528298A|JP3464382B2|1998-05-18|1998-05-18|Manufacturing method of vertical double diffusion MOSFET|
    JP10-135282||1998-05-18||
    US09/313,137|US6229178B1|1998-05-18|1999-05-17|Vertical double diffused MOSFET and method for manufacturing same|
    US09/728,990|US6376311B2|1998-05-18|2000-12-04|Vertical double diffused MOSFET and method for manufacturing same|US09/728,990| US6376311B2|1998-05-18|2000-12-04|Vertical double diffused MOSFET and method for manufacturing same|
    [返回顶部]