This nonprovisional application is based on Japanese Patent Application No. 2023-027256 filed on Feb. 24, 2023, with the Japan Patent Office, the entire contents of which are hereby incorporated by reference.
The present disclosure relates to a semiconductor device and a method for manufacturing a semiconductor device.
The semiconductor device disclosed in Japanese Patent Laying-Open No. 2018-117016 includes a semiconductor substrate, an interlayer insulating film, and a metal electrode. The semiconductor substrate has a first principal surface and a second principal surface opposite to the first principal surface. The interlayer insulating film is disposed on the second principal surface. A constituent material of the interlayer insulating film is boron phosphorus silicon glass (BPSG). The metal electrode is disposed on the interlayer insulating film.
In the semiconductor device disclosed in Japanese Patent Laying-Open No. 2018-117016, since the constituent material of the interlayer insulating film is BPSG containing phosphorus and boron, the interlayer insulating film is high in hygroscopicity and tends to contain moisture. As a result, the semiconductor device disclosed in Japanese Patent Laying-Open No. 2018-117016 has a possibility that the metal electrode disposed on the interlayer insulating film may be corroded by moisture.
The present disclosure has been made in view of the above-described problem with the related art. More specifically, the present disclosure provides a semiconductor device capable of inhibiting corrosion of an electrode disposed on an interlayer insulating film.
A semiconductor device of the present disclosure includes a semiconductor substrate, a TEOS film, and an electrode. The semiconductor substrate has a first principal surface and a second principal surface opposite to the first principal surface. The semiconductor substrate has an active region and a termination region surrounding the active region when the second principal surface is viewed along a direction of a normal to the second principal surface. The TEOS film is disposed on a part of the second principal surface located in the active region.
The foregoing 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.
Hereinafter, embodiments of the present disclosure will be described in detail with reference to drawings. In the following drawings, the same or corresponding parts are denoted by the same reference numerals to avoid the description from being redundant.
A semiconductor device according to a first embodiment will be described.
The semiconductor device according to the first embodiment is referred to as semiconductor device 100.
Hereinafter, the configuration of semiconductor device 100 will be described.
Semiconductor substrate 10 includes, for example, monocrystalline silicon. Semiconductor substrate 10 has a first principal surface 10a and a second principal surface 10b. Second principal surface 10b is a surface opposite to first principal surface 10a.
Semiconductor substrate 10 has an active region 11 and a termination region 12 as viewed from above (when second principal surface 10b is viewed along a direction of a normal to second principal surface 10b). Termination region 12 surrounds active region 11 as viewed from above. Termination region 12 has a channel stopper region 13. Channel stopper region 13 is located at an outer peripheral portion of termination region 12 as viewed from above.
A trench 10c is formed at a part of second principal surface 10b located in active region 11. Trench 10c extends from second principal surface 10b toward first principal surface 10a. Trench 10c may be further formed at a part of second principal surface 10b located in channel stopper region 13.
Semiconductor substrate 10 has a collector region 14, a buffer region 15, a drift region 16, a carrier storage region 17, a base region 18, and an emitter region 19.
Collector region 14 is disposed on first principal surface 10a. Buffer region 15 is disposed on collector region 14. Drift region 16 is disposed on buffer region 15. Carrier storage region 17 is disposed on a part of drift region 16 located in active region 11. Carrier storage region 17 may be further disposed on a part of drift region 16 located in channel stopper region 13. Base region 18 is disposed on carrier storage region 17. Emitter region 19 is disposed on base region 18 to serve as second principal surface 10b.
Buffer region 15, drift region 16, carrier storage region 17, and collector region 14 are of a first conductivity type. Collector region 14 and base region 18 are of a second conductivity type. The second conductivity type is a conductivity type opposite to the first conductivity type. For example, the first conductivity type is an n-type, and the second conductivity type is a p-type.
Semiconductor substrate 10 further has a well region 20. Well region 20 is disposed on second principal surface 10b located in termination region 12. Well region 20 is of the second conductivity type. Well region 20 has a relaxation region 21 and a reduced surface field (RESURF) region 22. RESURF region 22 is located outside relaxation region 21 as viewed from above. A dopant concentration of relaxation region 21 decreases from a side adjacent to active region 11 toward a side adjacent to RESURF region 22. A dopant concentration of RESURF region 22 decreases from a side adjacent to relaxation region 21 toward a side adjacent to channel stopper region 13.
Drift region 16, carrier storage region 17, base region 18, and emitter region 19 are exposed from a side wall surface of trench 10c. That is, a bottom of trench 10c reaches drift region 16. Base region 18 located on the side wall surface of trench 10c serves as a channel region.
Gate insulating film 23 is disposed on the side wall surface of trench 10c and the bottom surface of trench 10c. A constituent material of gate insulating film 23 is, for example, silicon oxide. Gate 24 is embedded in trench 10c. That is, gate 24 faces the channel region with gate insulating film 23 interposed between gate 24 and the channel region. Therefore, when a voltage is applied to gate 24, the channel region is inverted, and the IGBT is turned on. A constituent material of gate 24 is, for example, polycrystalline silicon containing a dopant.
Interlayer insulating film 30 is disposed on second principal surface 10b. In semiconductor device 100, interlayer insulating film 30 includes a TEOS film 31. A constituent material of TEOS film 31 is tetraethyl orthosilicate (TEOS). TEOS film 31 is substantially free of impurities such as phosphorus or boron. A contact hole 32 and a contact hole 33 are formed in interlayer insulating film 30. Contact hole 32 and contact hole 33 extend through interlayer insulating film 30 along a thickness direction. Emitter region 19 located in active region 11 is exposed from contact hole 32, and emitter region 19 located in channel stopper region 13 is exposed from contact hole 33.
Electrode 40 is disposed on first principal surface 10a. Electrode 40 is a collector electrode. A constituent material of electrode 40 is, for example, an aluminum-silicon alloy. Electrode 50 is disposed on interlayer insulating film 30 (TEOS film 31). Electrode 50 includes an emitter electrode 51, a gate electrode 52, a field plate electrode 53, and a channel stopper electrode 54. A constituent material of electrode 50 is, for example, an aluminum-silicon alloy.
Emitter electrode 51 is disposed on interlayer insulating film 30 disposed on a part of second principal surface 10b located in active region 11. Further, emitter electrode 51 is embedded in contact hole 32 to electrically connect to emitter region 19. Gate electrode 52 is disposed on interlayer insulating film 30 disposed on a part of second principal surface 10b located in termination region 12. Although not illustrated, gate electrode 52 is embedded in a contact hole formed in interlayer insulating film 30 other than contact hole 32 and contact hole 33 to electrically connect to gate 24.
Field plate electrode 53 is disposed on the interlayer insulating film 30 disposed on a part of second principal surface 10b located in termination region 12. More specifically, field plate electrode 53 faces RESURF region 22 with interlayer insulating film 30 interposed between field plate electrode 53 and RESURF region 22. Channel stopper electrode 54 is disposed on interlayer insulating film 30 disposed on a part of second principal surface 10b located in channel stopper region 13. Further, channel stopper electrode 54 is embedded in contact hole 33 to electrically connect to emitter region 19.
Semi-insulating film 60 is disposed on interlayer insulating film 30 so as to cover gate electrode 52, field plate electrode 53, and channel stopper electrode 54. Semi-insulating film 60 may cover a part of emitter electrode 51. A constituent material of semi-insulating film 60 is semi-insulating silicon nitride (SinSiN).
Hereinafter, a method for manufacturing semiconductor device 100 will be described.
In preparation process S1, semiconductor substrate 10 is prepared. After preparation process S1 is performed, ion implantation process S2 is performed.
Third, anisotropic dry etching is performed on semiconductor substrate 10 exposed from the hard mask. As a result, trench 10c is formed. Note that after trench 10c is formed, the hard mask is removed. After trench forming process S3 is performed, gate insulating film forming process S4 is performed.
Second, dry etching is performed, using the resist pattern as a mask, on interlayer insulating film 30 exposed from the opening of the resist pattern to form contact hole 32 and contact hole 33 in interlayer insulating film 30. Note that, although not illustrated, when contact hole 32 and contact hole 33 are formed, a contact hole in which gate 24 is embedded is also formed. After contact hole forming process S7 is performed, first electrode forming process S8 is performed.
Second, patterning is performed on the deposited constituent material of electrode 50. The patterning is performed on the deposited constituent material of electrode 50 by dry etching using, as a mask, a resist pattern formed on the deposited constituent material of deposited electrode 50. The resist pattern is formed by, for example, photolithography. After first electrode forming process S8 is performed, semi-insulating film forming process S9 is performed.
Hereinafter, effects produced by semiconductor device 100 will be described.
In a case where interlayer insulating film 30 includes BPSG, interlayer insulating film 30 becomes high in hygroscopicity and tends to contain moisture. As a result, electrode 50 disposed on interlayer insulating film 30 may be corroded by moisture.
In semiconductor device 100, however, interlayer insulating film 30 includes TEOS film 31, and TEOS film 31 includes TEOS substantially free of phosphorus or boron, thereby making interlayer insulating film 30 low in hygroscopicity. It is therefore possible for semiconductor device 100 to inhibit corrosion, caused by moisture, of the electrode disposed on interlayer insulating film 30.
In a case where interlayer insulating film 30 includes BPSG, embedding in a step portion or a groove is easily performed, and it is therefore possible to planarize the surface of interlayer insulating film 30. On the other hand, in a case where interlayer insulating film 30 includes the TEOS film, irregularities tend to remain on the surface of interlayer insulating film 30. In the method for manufacturing semiconductor device 100, however, when first electrode forming process S8 is performed, sputtering is performed with semiconductor substrate 10 heated to 400° C. or higher, so that the constituent material of electrode 50 is deposited on interlayer insulating film 30 while reflowing, and it is therefore possible to reduce the influence of irregularities remaining on the surface of interlayer insulating film 30 (that is, a possibility that the influence of irregularities of the surface of interlayer insulating film 30 may remain on the surface of electrode 50).
The example where semiconductor device 100 is an IGBT has been described above, but semiconductor device 100 is not limited to the example. Semiconductor device 100 may be a metal oxide semiconductor field effect transistor (MOSFET) or a diode.
A semiconductor device according to a second embodiment will be described. The semiconductor device according to the second embodiment is referred to as semiconductor device 100A. Here, differences from semiconductor device 100 will be mainly described to avoid the description from being redundant.
Hereinafter, the configuration of semiconductor device 100A will be described.
Note that thermal oxide film 34 is formed by thermal oxidation of second principal surface 10b located in termination region 12 before TEOS film 31 is formed in interlayer insulating film forming process S6. A heat treatment temperature when thermal oxide film 34 is formed is, for example, higher than or equal to 1000° C. A thickness of thermal oxide film 34 is preferably greater than or equal to 800 nm and less than or equal to 1200 nm.
Hereinafter, effects produced by semiconductor device 100A will be described.
In termination region 12, electric field intensity tends to be high. In semiconductor device 100A, however, thermal oxide film 34 is formed in addition to TEOS film 31, so that the electric field in termination region 12 is relaxed as compared with semiconductor device 100.
A semiconductor device according to a third embodiment will be described. The semiconductor device according to the third embodiment is referred to as semiconductor device 100B. Here, differences from semiconductor device 100A will be mainly described to avoid the description from being redundant.
Hereinafter, the configuration of semiconductor device 100B will be described.
Semiconductor device 100B further includes a plurality of conductor portions 70. The plurality of conductor portions 70 are arranged in thermal oxide film 34. The plurality of conductor portions 70 are arranged apart from each other. The plurality of conductor portions 70 are located between field plate electrode 53 and RESURF region 22. Conductor portions 70 are electrically floating. A constituent material of conductor portions 70 is a conductor. The constituent material of conductor portions 70 is, for example, polycrystalline silicon. In these respects, semiconductor device 100B is different in configuration from semiconductor device 100A.
Hereinafter, effects produced by semiconductor device 100B will be described.
In semiconductor device 100B, conductor portions 70 are arranged in thermal oxide film 34, so that the electric field in termination region 12 is further relaxed as compared with semiconductor device 100A.
A semiconductor device according to a fourth embodiment will be described. The semiconductor device according to the fourth embodiment is referred to as semiconductor device 100C. Here, differences from semiconductor device 100B will be mainly described to avoid the description from being redundant.
Hereinafter, the configuration of semiconductor device 100C will be described.
Semiconductor device 100C further includes an organic insulating film 80. A constituent material of organic insulating film 80 is, for example, an organic material such as polyimide. Organic insulating film 80 is disposed on a part of semi-insulating film 60 disposed on gate electrode 52, field plate electrode 53, and channel stopper electrode 54. A thickness of organic insulating film 80 is, for example, greater than or equal to 5 μm and less than or equal to 30 μm. In these respects, semiconductor device 100C is different in configuration from semiconductor device 100B.
Hereinafter, effects produced by semiconductor device 100C will be described.
In semiconductor device 100C, organic insulating film 80 is disposed on a part of semi-insulating film 60 disposed on gate electrode 52, field plate electrode 53, and channel stopper electrode 54. That is, in semiconductor device 100C, organic insulating film 80 is disposed on a part of semi-insulating film 60 other than a step part. The presence of organic insulating film 80 allows an increase in adhesion to an encapsulation resin (not illustrated) in which semiconductor device 100C is encapsulated. Therefore, semiconductor device 100C makes it possible to increase adhesion to the encapsulation resin in which semiconductor device 100C is encapsulated without worsening the electric field concentration at the step part of semi-insulating film 60.
A semiconductor device according to a fifth embodiment will be described. The semiconductor device according to the fifth embodiment is referred to as semiconductor device 100D. Here, differences from semiconductor device 100C will be mainly described to avoid the description from being redundant.
Hereinafter, the configuration of semiconductor device 100D will be described.
Semiconductor device 100D further includes a buffer film 90. A constituent material of buffer film 90 is, for example, silicon oxide. Buffer film 90 is formed by, for example, a CVD method. Buffer film 90 is lower in hardness than semi-insulating film 60. Buffer film 90 is interposed between gate electrode 52 and semi-insulating film 60, between field plate electrode 53 and semi-insulating film 60, and between channel stopper electrode 54 and semi-insulating film 60. In these respects, semiconductor device 100D is different in configuration from semiconductor device 100C.
A thickness of semi-insulating film 60 is denoted as thickness T. In semiconductor device 100D, thickness T is preferably greater than or equal to 1200 nm.
Hereinafter, effects produced by semiconductor device 100D will be described.
In semiconductor device 100D, buffer film 90 is interposed between gate electrode 52 and semi-insulating film 60, between field plate electrode 53 and semi-insulating film 60, and between channel stopper electrode 54 and semi-insulating film 60, and buffer film 90 is lower in hardness than semi-insulating film 60, so that external stress applied to semi-insulating film 60 is reduced.
Aspects of the present disclosure will be described collectively as an appendix.
A semiconductor device including:
The semiconductor device according to appendix 1, further including a thermal oxide film interposed between the second principal surface and the TEOS film.
The semiconductor device according to appendix 2, further including a conductor portion disposed in the thermal oxide film, in which the conductor portion is electrically floating.
The semiconductor device according to any one of appendixes 1 to 3, further including a semi-insulating film disposed on the TEOS film to cover the electrode.
The semiconductor device according to appendix 4, in which a thickness of the semi-insulating film is greater than or equal to 1.2 μm.
The semiconductor device according to appendix 4 or 5, further including an organic insulating film disposed on a part of the semi-insulating film disposed on the electrode.
The semiconductor device according to any one of appendixes 4 to 6, further including a buffer film interposed between the electrode and the semi-insulating film, in which the buffer film is lower in hardness than the semi-insulating film.
A method for manufacturing a semiconductor device, including:
Although the embodiments of the present invention have been described, it should be understood that the embodiments disclosed herein are illustrative in all respects and not restrictive. The scope of the present invention is interpreted by the terms of the appended claims, and the present invention is intended to include the claims, equivalents of the claims, and all modifications within the scope.
Number | Date | Country | Kind |
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2023-027256 | Feb 2023 | JP | national |