WO2020121508A1 - Semiconductor device - Google Patents

Semiconductor device Download PDF

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Publication number
WO2020121508A1
WO2020121508A1 PCT/JP2018/046035 JP2018046035W WO2020121508A1 WO 2020121508 A1 WO2020121508 A1 WO 2020121508A1 JP 2018046035 W JP2018046035 W JP 2018046035W WO 2020121508 A1 WO2020121508 A1 WO 2020121508A1
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WO
WIPO (PCT)
Prior art keywords
region
trench
semiconductor substrate
semiconductor device
semiconductor
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PCT/JP2018/046035
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French (fr)
Japanese (ja)
Inventor
嘉寿子 小川
Original Assignee
サンケン電気株式会社
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Application filed by サンケン電気株式会社 filed Critical サンケン電気株式会社
Priority to PCT/JP2018/046035 priority Critical patent/WO2020121508A1/en
Priority to JP2020559662A priority patent/JP7201005B2/en
Priority to KR1020217011061A priority patent/KR102472577B1/en
Priority to CN201880098705.8A priority patent/CN112913030B/en
Publication of WO2020121508A1 publication Critical patent/WO2020121508A1/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0611—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices
    • H01L29/0615—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE]
    • H01L29/0619—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for increasing or controlling the breakdown voltage of reverse biased devices by the doping profile or the shape or the arrangement of the PN junction, or with supplementary regions, e.g. junction termination extension [JTE] with a supplementary region doped oppositely to or in rectifying contact with the semiconductor containing or contacting region, e.g. guard rings with PN or Schottky junction
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/02—Semiconductor bodies ; Multistep manufacturing processes therefor
    • H01L29/06—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions
    • H01L29/0603—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions
    • H01L29/0607—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration
    • H01L29/0638—Semiconductor bodies ; Multistep manufacturing processes therefor characterised by their shape; characterised by the shapes, relative sizes, or dispositions of the semiconductor regions ; characterised by the concentration or distribution of impurities within semiconductor regions characterised by particular constructional design considerations, e.g. for preventing surface leakage, for controlling electric field concentration or for internal isolations regions for preventing surface leakage or controlling electric field concentration for preventing surface leakage due to surface inversion layer, e.g. with channel stopper
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/40—Electrodes ; Multistep manufacturing processes therefor
    • H01L29/402—Field plates
    • H01L29/407—Recessed field plates, e.g. trench field plates, buried field plates
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L29/00—Semiconductor devices adapted for rectifying, amplifying, oscillating or switching, or capacitors or resistors with at least one potential-jump barrier or surface barrier, e.g. PN junction depletion layer or carrier concentration layer; Details of semiconductor bodies or of electrodes thereof  ; Multistep manufacturing processes therefor
    • H01L29/66—Types of semiconductor device ; Multistep manufacturing processes therefor
    • H01L29/68—Types of semiconductor device ; Multistep manufacturing processes therefor controllable by only the electric current supplied, or only the electric potential applied, to an electrode which does not carry the current to be rectified, amplified or switched
    • H01L29/76—Unipolar devices, e.g. field effect transistors
    • H01L29/772—Field effect transistors
    • H01L29/78—Field effect transistors with field effect produced by an insulated gate

Definitions

  • the present invention relates to a semiconductor device in which a structure for improving breakdown voltage is formed.
  • a structure for improving the breakdown voltage is formed in the peripheral region around the element region where the semiconductor element is formed.
  • the withstand voltage of a semiconductor device is improved by arranging a trench in which an electrode is embedded inside a groove having an insulating film formed on an inner wall surface in a peripheral region to reduce concentration of an electric field (Patent Document 1). See 1.).
  • a plurality of trenches each having a conductor film arranged inside the groove are multiply arranged in the peripheral region surrounding the periphery of the element region, and the width of the semiconductor substrate sandwiched between adjacent trenches is Provided is a semiconductor device in which the inner region close to the element region is wider than the outer region located around the inner region.
  • FIG. 9 is a schematic cross-sectional view showing another configuration of the trench of the semiconductor device according to the modified example of the first embodiment of the present invention. It is a typical sectional view showing composition of a semiconductor device concerning a 2nd embodiment of the present invention.
  • the semiconductor device As shown in FIG. 1, the semiconductor device according to the first exemplary embodiment of the present invention includes a semiconductor substrate 10 in which an element region 110 and a peripheral region 120 surrounding the element region 110 are defined on the upper surface.
  • the semiconductor substrate 10 has a configuration in which a second conductive type second semiconductor layer 12 is stacked on a first conductive type first semiconductor layer 11.
  • a protective film 30 is formed on the upper surface of the semiconductor substrate 10.
  • the first conductivity type and the second conductivity type are opposite conductivity types. That is, if the first conductivity type is n-type, the second conductivity type is p-type, and if the first conductivity type is p-type, the second conductivity type is n-type.
  • the first conductivity type is n-type and the second conductivity type is p-type will be described. That is, the first semiconductor layer 11 of the semiconductor substrate 10 is n-type and the second semiconductor layer 12 is p-type.
  • a plurality of trenches 20 surrounding the element region 110 are arranged in multiple and spaced from each other. That is, in plan view, the plurality of annular trenches 20 are arranged around the element region 110.
  • the trench 20 has an insulating film 21 arranged on the inner wall surface of the groove extending from the upper surface of the semiconductor substrate 10 in the film thickness direction, and a conductor film 22 arranged on the insulating film 21 inside the groove.
  • the trench of the trench 20 extends from the upper surface of the second semiconductor layer 12 and reaches the first semiconductor layer 11.
  • the conductor film 22 and the semiconductor substrate 10 face each other with the insulating film 21 in between, and the bottom portion of the insulating film 21 includes the first semiconductor layer 11 and the second semiconductor layer 12 that are in contact with the side surface of the groove. It is located below the joint.
  • the conductor film 22 arranged inside the trench 20 is in an electrically floating state.
  • the second semiconductor layer 12 in the element region 110 is electrically connected to the surface electrode (not shown) of the semiconductor device.
  • the second semiconductor layer 12 in the peripheral region 120 is in an electrically floating state.
  • the channel stopper electrode 50 formed on the upper surface of the semiconductor substrate 10 on the end side is electrically connected to the back surface electrode 60 via the channel stopper region 40 arranged along the outer edge of the upper surface of the semiconductor substrate 10. ..
  • a part of the upper portion of the conductor film 22 of the trench 20 of the semiconductor substrate 10 is interposed via the insulating film. It extends to the upper surface of the region where the trench 20 is not arranged.
  • a portion of the conductor film 22 extending on the upper surface of the semiconductor substrate 10 is shown as an extending portion 221 (the same applies below).
  • the extending portion 221 is electrically connected to the conductor film 22.
  • the conductor film 22 of the trench 20 does not have to extend to the upper surface of the semiconductor substrate 10.
  • the distance (length L in FIG. 1) along the upper surface of the semiconductor substrate 10 of the extending portion 221 may be shorter in the outer region 122 than in the inner region 121.
  • vertical switching elements such as MOSFETs and IGBTs having a gate trench structure are formed in the element region 110.
  • the back surface electrode is formed on the back surface of the semiconductor substrate 10.
  • the semiconductor device When the semiconductor device is turned off or in the reverse bias state, a potential distribution as shown by the equipotential surface S in FIG. 2 occurs in the peripheral region 120.
  • the depletion layer By extending the depletion layer from the side surface and the bottom surface of the trench 20, the depletion layer spreads laterally and downward in the peripheral region 120, and the concentration of the electric field is relaxed. As a result, the breakdown voltage of the semiconductor device can be improved.
  • the electric field concentrates closer to the element region 110. Therefore, the distance between the trenches 20 in the inner region 121 (the width of the semiconductor substrate 10 in a region sandwiched by the adjacent trenches 20 in plan view) is longer than the distance between the trenches 20 in the outer region 122. Further, in the inner region 121, the closer the distance between the trenches 20 is to the element region 110, the wider the distance is set. Incidentally, the distance between the trenches 20 may be wider as it is closer to the element region 110, or may be constant.
  • the trench 20 is formed as follows, for example. That is, after forming the groove of the trench 20 in the peripheral region 120, the insulating film 21 is formed on the inner wall surface of the groove by using a thermal oxidation method or the like. Next, the conductor film 22 is formed inside the groove.
  • the conductor film 22 is, for example, a polysilicon film doped with impurities.
  • the conductor film 22 is formed on the entire upper surface of the semiconductor substrate 10 so that the groove is filled with the conductor film 22.
  • the conductor film 22 of the trench 20 in the inner region 121 is patterned by photolithography or the like so that the extending portion 221 remains on the upper surface of the semiconductor substrate 10.
  • the upper surface of the conductor film 22 may be lower than the upper surface of the semiconductor substrate 10 when the conductor film 22 is flattened. There is a problem of going down.
  • the structure in which the extending portion 221 remains on the upper surface of the semiconductor substrate 10 has an advantage that a stable breakdown voltage can be obtained without being affected by etching variations.
  • the upper surface of the semiconductor substrate 10 is positioned so that the position of the upper surface of the conductor film 22 of the trench 20 is lower than or substantially the same as the position of the upper surface of the semiconductor substrate 10. The conductor film 22 above is removed.
  • the groove of the trench 20 may be formed at the same time when the gate trench is formed. Then, the insulating film 21 of the trench 20 is formed simultaneously with the formation of the gate insulating film on the inner wall surface of the gate trench, and the conductor film 22 is formed simultaneously with the formation of the gate electrode. At this time, the width of the trench 20 may be the same throughout the peripheral region 120.
  • the electric field is concentrated in the corner portion C facing the element region 110 at the bottom of the trench 20.
  • the electric field is more concentrated in the corner portion C of the bottom of the trench 20 closer to the element region 110 and facing the element region 110.
  • the extending portion 221 of the trench 20 extends from the opening of the trench 20 onto the upper surface of the semiconductor substrate 10 with the insulating film interposed therebetween. Extending to the side. Thereby, as described below, the concentration of the electric field at the corner portion C can be relaxed.
  • a depletion layer is formed on the side surface and the bottom surface of the trench 20.
  • the electric field concentration is more likely to occur on the side surface of the trench 20 on the element region side than on the side surface outside the trench 20.
  • electric field concentration is more likely to occur in the trench 20 in the inner region 121 than in the outer region 122.
  • the inner region 121 since a depletion layer is also formed in the semiconductor substrate 10 below the extending part 221, the interval between the equipotential surfaces on the side surface side of the trench 20 in the inner region 121 on the element region 110 side is wide, and the corner part is formed. The concentration of the electric field at C is relaxed.
  • FIG. 3 and 4 show examples of results of simulation of the potential distribution of the semiconductor substrate 10 and the state of the depletion layer.
  • FIG. 3 shows the equipotential surfaces S1 to S4 and the depletion layer of the trench 20 of the comparative example in which the extending portion 221 is not formed.
  • FIG. 4 shows an example of a situation of equipotential surfaces S1 to S4 of the trench 20 in which the extension portion 221 is formed and the depletion layer.
  • the equipotential surface S1 is an equipotential surface near the element region 110, and the equipotential surfaces S2 to S4 are equipotential surfaces outside the equipotential surface S1.
  • the equipotential surface spacing becomes wider, the concentration of the electric field is further alleviated, and the side surface and the extending portion of the trench 20 are extended.
  • the depletion layer spreads near the upper surface of the semiconductor substrate 10 below the portion 221. As a result, the breakdown voltage of the semiconductor device is improved.
  • the length L of the extending portion 221 that extends in the direction toward the element region 110 may be increased as the trench 20 is closer to the element region 110. Further, the length L of the extension portion 221 extending from the trench 20 close to the element region 110 may be longer than the length L of the extension portion 221 extending from the trench 20 close to the outer region 122.
  • the length L of the extending portion 221 extending from the remaining trench 20 in the middle thereof is, for example, 4 ⁇ m, 4 ⁇ m, 3.5 ⁇ m, 3 ⁇ m, 2.5 ⁇ m, 2 ⁇ m, and stepwise for each single or plural trenches 20. It may be shorter in order from the trench 20 on the element region 110 side. Further, the extending portion 221 extending from the remaining trench 20 may have a constant length.
  • the conductor film 22 is not arranged on the upper surface of the semiconductor substrate 10 in the trench 20 arranged in the outer region 122 of the peripheral region 120. This prevents the equipotential surfaces from being widened in the outer region 122 as in the inner region 121. Therefore, the depletion layer is suppressed from extending to the outer edge of the semiconductor substrate 10.
  • the extending portion 221 of the trench 20 is preferable to form only in the inner region 121 where the electric field is likely to be concentrated because it is close to the element region 110.
  • the position of the boundary between the inner region 121 and the outer region 122 of the peripheral region 120 can be set according to the breakdown voltage required for the semiconductor device. As the number of trenches 20 forming the extending portion 221 increases and the inner region 121 expands outward, a region having a wide equipotential surface interval extends outward. As a result, there is a possibility that reliability problems such as generation of leakage current and reduction of breakdown voltage may occur.
  • FIG. 5 shows the results of the investigation conducted by the present inventors on the relationship between the trench ratio P1/P2 and the breakdown voltage of the semiconductor device.
  • the trench ratio P1/P2 exceeds 1.5, the breakdown voltage becomes stable. Therefore, the region where the trench ratio P1/P2 is smaller than 1.5 is defined as the inner region 121. As a result, the breakdown voltage of the semiconductor device can be effectively improved without expanding the inner region 121 too much.
  • the extending portion 221 that is a part of the conductor film 22 has the semiconductor substrate 10. It extends on the upper surface through an insulating film. This widens the equipotential surface of the semiconductor substrate 10 to control the extension of the depletion layer and alleviate the concentration of the electric field in the peripheral region 120.
  • the breakdown voltage can be improved without increasing the number of surrounding trenches 20 surrounding the element region 110. Therefore, it is possible to realize a semiconductor device having an improved breakdown voltage while suppressing an increase in chip size.
  • a capacitance is generated between the extending portion 221 and the semiconductor substrate 10 below the extending portion 221, and the capacitance generated inside the trench 20 is larger than that when the extending portion 221 is not provided.
  • the voltage applied to the insulating film 21 of the trench 20 can be reduced. This also improves the reliability of the semiconductor device.
  • the extending portion 221 of the conductor film 22 of the trench 20 extends from the opening of the trench 20 toward the region near the element region 110.
  • the extending portion 221 may be arranged at the portion.
  • the extending portion 221 may be arranged only in the portion extending from the opening of the trench 20 toward the region near the outer edge of the semiconductor substrate 10.
  • the depth of the trench 20 is shallower in the inner region 121 than in the outer region 122. That is, the inner region 121 and the outer region 122 have different groove depths of the trench 20, which is a difference from the first embodiment.
  • Other configurations are similar to those of the first embodiment shown in FIG.
  • the distance T from the bottom of the groove of the trench 20 to the PN junction surface of the first semiconductor layer 11 and the second semiconductor layer 12 which is in contact with the groove of the trench 20. Can be shortened.
  • the interval between the equipotential surfaces at the bottom of the trench 20 in the inner region 121 becomes wider, and the concentration of electric field can be relaxed. Therefore, the breakdown voltage of the semiconductor device can be improved.
  • the depth of the groove of the trench 20 in the inner region 121 is, for example, about 4.0 ⁇ m, and from the bottom of the groove of the trench 20 to the PN junction surface between the first semiconductor layer 11 and the second semiconductor layer 12 that is in contact with the side surface of the groove.
  • the distance T is 0 to 0.5 ⁇ m.
  • the depth of the groove of the trench 20 in the outer region 122 is, for example, about 4.5 ⁇ m, and the PN junction between the first semiconductor layer 11 and the second semiconductor layer 12 in contact with the side surface of the groove from the bottom of the groove of the trench 20.
  • the distance T to the surface is 0.5 ⁇ m to 1.5 ⁇ m.
  • the width of the groove of the trench 20 in the inner region 121 is made narrower than the width of the groove of the trench 20 in the outer region 122.
  • a mask for forming such a groove is provided on the semiconductor substrate 10, the grooves of the trench 20 in the inner region 121 and the outer region 122 are simultaneously formed under the same process condition, and the trench 20 is formed in the region 121 inside the outer region 122.
  • the groove can be formed shallowly.
  • the groove of the trench 20 in the inner region 121 and the groove of the trench 20 in the outer region 122 may be formed in different steps under different process conditions.
  • the depth of the second conductivity type (p-type) semiconductor region such as the base region formed on the upper surface side of the semiconductor substrate 10 of the element region 110 formed with the FET or the IGBT and the depth of the second semiconductor layer 12 are The depths may be the same or different. For example, when the depth of the second-conductivity-type semiconductor region such as the base region of the element region 110 is shallower than the depth of the trench 20, the depth of the second-conductivity-type semiconductor region such as the base region of the element region 110 is smaller than that of the second-conductivity-type semiconductor region. 2 The depth of the semiconductor layer 12 may be increased. Thus, the distance T can be adjusted as appropriate without depending on the depth of the second conductivity type semiconductor region of the element region 110.
  • the depth of the trench 20 in the inner region 121 and the depth of the trench 20 in the outer region 122 are set to be substantially the same, and the depth of the second semiconductor layer 12 in the inner region 121 is set to the second semiconductor in the outer region 122. It may be deeper than the depth of layer 12. Accordingly, even if the groove depth of the trench 20 in the inner region 121 and the groove depth of the trench 20 in the outer region 122 are substantially the same, the distance T can be appropriately adjusted.
  • the breakdown voltage can be further improved while suppressing the increase in chip size.
  • Others are substantially the same as those in the first embodiment, and duplicate description will be omitted.
  • the second embodiment also has the configuration including the extending portion 221 as in the first embodiment, but the second embodiment does not include the extending portion 221. Even without it, the concentration of the electric field can be relaxed and the breakdown voltage of the semiconductor device can be improved.
  • the semiconductor device of the present invention can be used in the electronic equipment industry including the manufacturing industry that manufactures semiconductor devices that require high breakdown voltage.

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  • Engineering & Computer Science (AREA)
  • Microelectronics & Electronic Packaging (AREA)
  • Power Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Ceramic Engineering (AREA)
  • Condensed Matter Physics & Semiconductors (AREA)
  • General Physics & Mathematics (AREA)
  • Computer Hardware Design (AREA)
  • Electrodes Of Semiconductors (AREA)
  • Metal-Oxide And Bipolar Metal-Oxide Semiconductor Integrated Circuits (AREA)

Abstract

This semiconductor device includes a semiconductor substrate (10) which has, defined on a top surface thereof, an element region (110) and a surrounding region (120) that surrounds the element region (110). A plurality of trenches (20) are arranged surrounding the element region (110) in multiple layers in the surrounding region (120), each of the trenches (20) having an insulating film (21) that is disposed on an inner wall of a groove extending from the top surface of the semiconductor substrate (10) in the film thickness direction and a conductor film (22) that is disposed on the insulating film (21) inside the groove. The surrounding region (120) has an inner region (121) that is close to the element region (110) and an outer region (122) that is positioned around the inner region (121), and the widths of the semiconductor substrate (10) between adjoining trenches (20) are larger in the inner region (121) than in the outer region (122).

Description

半導体装置Semiconductor device
  本発明は、耐圧向上のための構造が形成される半導体装置に関する。 The present invention relates to a semiconductor device in which a structure for improving breakdown voltage is formed.
　半導体装置の耐圧を向上させるために、半導体素子が形成される素子領域の周囲の周辺領域に耐圧を向上するための構造が形成されている。例えば、内壁面に絶縁膜を形成した溝の内部に電極が埋め込まれたトレンチを周辺領域に配置して電界の集中を緩和することにより、半導体装置の耐圧の向上が図られている（特許文献１参照。）。 In order to improve the breakdown voltage of the semiconductor device, a structure for improving the breakdown voltage is formed in the peripheral region around the element region where the semiconductor element is formed. For example, the withstand voltage of a semiconductor device is improved by arranging a trench in which an electrode is embedded inside a groove having an insulating film formed on an inner wall surface in a peripheral region to reduce concentration of an electric field (Patent Document 1). See 1.).
特開２０１３－５５３４７号公報JP, 2013-55347, A
　大電流のスイッチング動作を行うパワー半導体素子などには、更なる耐圧の向上が望まれている。しかしながら、電極を埋め込んだトレンチを素子領域の周囲に配置する構造によって更に耐圧を向上させるためには、素子領域の周囲を囲むトレンチの囲み数を増やすために周辺領域の幅を広げる必要がある。このため、チップサイズが増大する問題があった。 ▽ For semiconductor devices such as power semiconductors that perform high-current switching operations, further improvement in breakdown voltage is desired. However, in order to further improve the breakdown voltage by the structure in which the trenches in which the electrodes are embedded are arranged around the element region, it is necessary to widen the width of the peripheral region in order to increase the number of trenches surrounding the element region. Therefore, there is a problem that the chip size increases.
　上記問題点に鑑み、本発明は、チップサイズの増大を抑制しつつ、耐圧が向上された半導体装置を提供することを目的とする。 In view of the above problems, it is an object of the present invention to provide a semiconductor device having an improved breakdown voltage while suppressing an increase in chip size.
　本発明の一態様によれば、溝の内部に導電体膜を配置した複数のトレンチが素子領域の周囲を囲んで周辺領域に多重に配置され、隣接するトレンチに挟まれた半導体基体の幅は、素子領域に近い内側領域の方が、内側領域の周囲に位置する外側領域よりも広い半導体装置が提供される。 According to one embodiment of the present invention, a plurality of trenches each having a conductor film arranged inside the groove are multiply arranged in the peripheral region surrounding the periphery of the element region, and the width of the semiconductor substrate sandwiched between adjacent trenches is Provided is a semiconductor device in which the inner region close to the element region is wider than the outer region located around the inner region.
　本発明によれば、チップサイズの増大を抑制しつつ、耐圧が向上された半導体装置を提供できる。 According to the present invention, it is possible to provide a semiconductor device having an improved breakdown voltage while suppressing an increase in chip size.
本発明の第１の実施形態に係る半導体装置の構成を示す模式的な断面図である。It is a typical sectional view showing composition of a semiconductor device concerning a 1st embodiment of the present invention. 半導体基体の等電位面と空乏層の広がりを示す模式図である。It is a schematic diagram which shows the equipotential surface of a semiconductor substrate, and the spread of a depletion layer. 比較例の等電位面と空乏層の広がりの例を示す模式図である。It is a schematic diagram which shows the equipotential surface of a comparative example, and the example of expansion of a depletion layer. 本発明の第１の実施形態に係る半導体装置の等電位面の例を示す模式図である。It is a schematic diagram which shows the example of the equipotential surface of the semiconductor device which concerns on the 1st Embodiment of this invention. トレンチ比と半導体装置の耐圧の関係を示すグラフである。7 is a graph showing the relationship between the trench ratio and the breakdown voltage of the semiconductor device. 本発明の第１の実施形態の変形例に係る半導体装置のトレンチの構成を示す模式的な断面図である。It is a typical sectional view showing the composition of the trench of the semiconductor device concerning the modification of a 1st embodiment of the present invention. 本発明の第１の実施形態の変形例に係る半導体装置のトレンチの他の構成を示す模式的な断面図である。FIG. 9 is a schematic cross-sectional view showing another configuration of the trench of the semiconductor device according to the modified example of the first embodiment of the present invention. 本発明の第２の実施形態に係る半導体装置の構成を示す模式的な断面図である。It is a typical sectional view showing composition of a semiconductor device concerning a 2nd embodiment of the present invention.
　次に、図面を参照して、本発明の実施形態を説明する。以下の図面の記載において、同一又は類似の部分には同一又は類似の符号を付している。ただし、図面は模式的なものであり、厚みと平面寸法との関係、各部の長さの比率などは現実のものとは異なることに留意すべきである。したがって、具体的な寸法は以下の説明を参酌して判断すべきものである。また、図面相互間においても互いの寸法の関係や比率が異なる部分が含まれていることはもちろんである。 Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar reference numerals are given to the same or similar parts. However, it should be noted that the drawings are schematic, and the relationship between the thickness and the plane dimension, the ratio of the length of each part, and the like are different from the actual ones. Therefore, specific dimensions should be determined in consideration of the following description. Further, it is needless to say that the drawings include portions in which dimensional relationships and ratios are different from each other.
　また、以下に示す実施形態は、この発明の技術的思想を具体化するための装置や方法を例示するものである。この発明の技術的思想は、構成部品の形状、構造、配置などを下記のものに特定するものでない。 Further, the following embodiments exemplify devices and methods for embodying the technical idea of the present invention. The technical idea of the present invention does not specify the shape, structure, arrangement, etc. of the constituent parts to the following.
　（第１の実施形態）
　本発明の第１の実施形態に係る半導体装置は、図１に示すように、素子領域１１０と素子領域１１０の周囲を囲む周辺領域１２０が上面に定義された半導体基体１０を備える。半導体基体１０は、第１導電型の第１半導体層１１の上に第２導電型の第２半導体層１２が積層された構成である。半導体基体１０の上面には、保護膜３０が形成されている。 (First embodiment)
As shown in FIG. 1, the semiconductor device according to the first exemplary embodiment of the present invention includes a semiconductor substrate 10 in which an element region 110 and a peripheral region 120 surrounding the element region 110 are defined on the upper surface. The semiconductor substrate 10 has a configuration in which a second conductive type second semiconductor layer 12 is stacked on a first conductive type first semiconductor layer 11. A protective film 30 is formed on the upper surface of the semiconductor substrate 10.
　第１導電型と第２導電型とは互いに反対導電型である。即ち、第１導電型がｎ型であれば、第２導電型はｐ型であり、第１導電型がｐ型であれば、第２導電型はｎ型である。以下では、第１導電型がｎ型、第２導電型がｐ型の場合を説明する。つまり、半導体基体１０の第１半導体層１１はｎ型であり、第２半導体層１２はｐ型である。 The first conductivity type and the second conductivity type are opposite conductivity types. That is, if the first conductivity type is n-type, the second conductivity type is p-type, and if the first conductivity type is p-type, the second conductivity type is n-type. Hereinafter, a case where the first conductivity type is n-type and the second conductivity type is p-type will be described. That is, the first semiconductor layer 11 of the semiconductor substrate 10 is n-type and the second semiconductor layer 12 is p-type.
　周辺領域１２０には、素子領域１１０の周囲を囲んで複数のトレンチ２０が互いに離間して多重に配置されている。即ち、平面視で、複数の環状のトレンチ２０が素子領域１１０の周囲に配置されている。トレンチ２０は、半導体基体１０の上面から膜厚方向に延伸する溝の内壁面に配置された絶縁膜２１、及び溝の内部で絶縁膜２１の上に配置された導電体膜２２を有する。トレンチ２０の溝は、第２半導体層１２の上面から延伸して第１半導体層１１に達する。トレンチ２０の底面及び側面では、絶縁膜２１を介して導電体膜２２と半導体基体１０が対向し、絶縁膜２１の底部は、溝の側面と接する第１半導体層１１と第２半導体層１２との接合部よりも下側に位置する。トレンチ２０の内部に配置された導電体膜２２は、電気的にフローティング状態である。素子領域１１０の第２半導体層１２は、半導体装置の表面電極（不図示）と電気的に接続している。周辺領域１２０の第２半導体層１２は、電気的にフローティング状態である。半導体基体１０の上面の外縁に沿って配置されたチャネルストッパ領域４０を介して、半導体基体１０の端部側の上面に形成されたチャネルストッパ電極５０が裏面電極６０と電気的に接続している。 In the peripheral region 120, a plurality of trenches 20 surrounding the element region 110 are arranged in multiple and spaced from each other. That is, in plan view, the plurality of annular trenches 20 are arranged around the element region 110. The trench 20 has an insulating film 21 arranged on the inner wall surface of the groove extending from the upper surface of the semiconductor substrate 10 in the film thickness direction, and a conductor film 22 arranged on the insulating film 21 inside the groove. The trench of the trench 20 extends from the upper surface of the second semiconductor layer 12 and reaches the first semiconductor layer 11. On the bottom surface and the side surface of the trench 20, the conductor film 22 and the semiconductor substrate 10 face each other with the insulating film 21 in between, and the bottom portion of the insulating film 21 includes the first semiconductor layer 11 and the second semiconductor layer 12 that are in contact with the side surface of the groove. It is located below the joint. The conductor film 22 arranged inside the trench 20 is in an electrically floating state. The second semiconductor layer 12 in the element region 110 is electrically connected to the surface electrode (not shown) of the semiconductor device. The second semiconductor layer 12 in the peripheral region 120 is in an electrically floating state. The channel stopper electrode 50 formed on the upper surface of the semiconductor substrate 10 on the end side is electrically connected to the back surface electrode 60 via the channel stopper region 40 arranged along the outer edge of the upper surface of the semiconductor substrate 10. ..
　図１に示すように、周辺領域１２０のうち素子領域１１０に近い一定の範囲の内側領域１２１においては、トレンチ２０の導電体膜２２の上部の一部が、絶縁膜を介して半導体基体１０のトレンチ２０の配置されていない領域の上面に延在する。図１では、半導体基体１０の上面に延在する導電体膜２２の部分を延在部２２１として示している（以下において同様。）。延在部２２１は導電体膜２２と電気的に接続している。一方、周辺領域１２０のうち内側領域１２１の周囲を囲む外側領域１２２においては、トレンチ２０の導電体膜２２は半導体基体１０の上面に延在していなくてもよい。なお、延在部２２１の半導体基体１０の上面に沿った距離（図１の長さＬ）を、外側領域１２２において内側領域１２１よりも短くしてもよい。 As shown in FIG. 1, in the inner region 121 of the peripheral region 120 in a certain range close to the element region 110, a part of the upper portion of the conductor film 22 of the trench 20 of the semiconductor substrate 10 is interposed via the insulating film. It extends to the upper surface of the region where the trench 20 is not arranged. In FIG. 1, a portion of the conductor film 22 extending on the upper surface of the semiconductor substrate 10 is shown as an extending portion 221 (the same applies below). The extending portion 221 is electrically connected to the conductor film 22. On the other hand, in the outer region 122 surrounding the inner region 121 of the peripheral region 120, the conductor film 22 of the trench 20 does not have to extend to the upper surface of the semiconductor substrate 10. The distance (length L in FIG. 1) along the upper surface of the semiconductor substrate 10 of the extending portion 221 may be shorter in the outer region 122 than in the inner region 121.
　図示を省略するが、素子領域１１０には、例えばゲートトレンチ構造のＭＯＳＦＥＴやＩＧＢＴなどの縦型スイッチング素子が形成される。縦型スイッチング素子が素子領域１１０に形成された場合、半導体基体１０の裏面に裏面電極が形成される。 Although illustration is omitted, vertical switching elements such as MOSFETs and IGBTs having a gate trench structure are formed in the element region 110. When the vertical switching element is formed in the element region 110, the back surface electrode is formed on the back surface of the semiconductor substrate 10.
　半導体装置をオフ又は逆バイアス状態にした場合に、図２に等電位面Ｓで示すような電位分布が周辺領域１２０に生じる。トレンチ２０の側面及び底面から空乏層が伸びることにより、周辺領域１２０において空乏層が横方向・下方向に広がり、電界の集中が緩和される。これにより、半導体装置の耐圧を向上させることができる。なお、素子領域１１０に近いほど電界が集中する。このため、内側領域１２１のトレンチ２０間の距離（隣り合うトレンチ２０で挟まれた領域の半導体基体１０の平面視の幅）は、外側領域１２２のトレンチ２０間の距離よりも長くなっている。更に内側領域１２１において、トレンチ２０間の距離が素子領域１１０に近いほど広く設定されている。ちなみに、トレンチ２０間の距離は素子領域１１０に近い程広くしてもよいし、一定であってもよい。 When the semiconductor device is turned off or in the reverse bias state, a potential distribution as shown by the equipotential surface S in FIG. 2 occurs in the peripheral region 120. By extending the depletion layer from the side surface and the bottom surface of the trench 20, the depletion layer spreads laterally and downward in the peripheral region 120, and the concentration of the electric field is relaxed. As a result, the breakdown voltage of the semiconductor device can be improved. Note that the electric field concentrates closer to the element region 110. Therefore, the distance between the trenches 20 in the inner region 121 (the width of the semiconductor substrate 10 in a region sandwiched by the adjacent trenches 20 in plan view) is longer than the distance between the trenches 20 in the outer region 122. Further, in the inner region 121, the closer the distance between the trenches 20 is to the element region 110, the wider the distance is set. Incidentally, the distance between the trenches 20 may be wider as it is closer to the element region 110, or may be constant.
　トレンチ２０は、例えば、以下のように形成される。即ち、周辺領域１２０にトレンチ２０の溝を形成した後に、熱酸化法などを用いて溝の内壁面に絶縁膜２１を形成する。次いで、溝の内部に導電体膜２２を形成する。導電体膜２２は、不純物がドープされたポリシリコン膜などである。例えば、溝が導電体膜２２で埋め込まれるように、半導体基体１０の上面の全面に導電体膜２２を形成する。そして、フォトリソグラフィ技術などを用いて、延在部２２１が半導体基体１０の上面に残るように、内側領域１２１のトレンチ２０の導電体膜２２をパターニングする。従来構造のような延在部２２１を有しない構造の場合、導電体膜２２を平坦化する際、導電体膜２２の上面を半導体基体１０の上面より低くすることがあり、低くするほど耐圧が下がるという問題がある。第１の実施形態のように、延在部２２１が半導体基体１０の上面に残る構造とすることで、エッチングバラツキに影響されず安定した耐圧を得られるという利点を有する。一方、外側領域１２２については、トレンチ２０の導電体膜２２の上面の位置が、半導体基体１０の上面の位置よりも下方又は半導体基体１０の上面とほぼ同じになるように、半導体基体１０の上面の上の導電体膜２２が除去される。 The trench 20 is formed as follows, for example. That is, after forming the groove of the trench 20 in the peripheral region 120, the insulating film 21 is formed on the inner wall surface of the groove by using a thermal oxidation method or the like. Next, the conductor film 22 is formed inside the groove. The conductor film 22 is, for example, a polysilicon film doped with impurities. For example, the conductor film 22 is formed on the entire upper surface of the semiconductor substrate 10 so that the groove is filled with the conductor film 22. Then, the conductor film 22 of the trench 20 in the inner region 121 is patterned by photolithography or the like so that the extending portion 221 remains on the upper surface of the semiconductor substrate 10. In the case of a structure having no extending portion 221 like the conventional structure, the upper surface of the conductor film 22 may be lower than the upper surface of the semiconductor substrate 10 when the conductor film 22 is flattened. There is a problem of going down. As in the first embodiment, the structure in which the extending portion 221 remains on the upper surface of the semiconductor substrate 10 has an advantage that a stable breakdown voltage can be obtained without being affected by etching variations. On the other hand, with respect to the outer region 122, the upper surface of the semiconductor substrate 10 is positioned so that the position of the upper surface of the conductor film 22 of the trench 20 is lower than or substantially the same as the position of the upper surface of the semiconductor substrate 10. The conductor film 22 above is removed.
　なお、素子領域１１０にゲートトレンチ構造の半導体素子を形成する場合に、ゲートトレンチの形成と同時にトレンチ２０の溝を形成してもよい。そして、ゲートトレンチの内壁面にゲート絶縁膜を形成するのと同時にトレンチ２０の絶縁膜２１を形成し、ゲート電極の形成と同時に導電体膜２２を形成する。このとき、トレンチ２０の溝の幅は、周辺領域１２０の全域で同一にしてもよい。 When forming a semiconductor element having a gate trench structure in the element region 110, the groove of the trench 20 may be formed at the same time when the gate trench is formed. Then, the insulating film 21 of the trench 20 is formed simultaneously with the formation of the gate insulating film on the inner wall surface of the gate trench, and the conductor film 22 is formed simultaneously with the formation of the gate electrode. At this time, the width of the trench 20 may be the same throughout the peripheral region 120.
　図１に示した半導体装置では、トレンチ２０の底部の素子領域１１０に対向するコーナー部Ｃに、電界が集中する。特に、素子領域１１０に近いトレンチ２０の底部の素子領域１１０に対向するコーナー部Ｃほど電界が集中する。図１に示した半導体装置では、素子領域１１０に近い内側領域１２１において、トレンチ２０の延在部２２１が、トレンチ２０の開口部から半導体基体１０の上面の上に絶縁膜を介して素子領域１１０側へ延在している。これにより、以下に説明するように、コーナー部Ｃでの電界の集中を緩和できる。 In the semiconductor device shown in FIG. 1, the electric field is concentrated in the corner portion C facing the element region 110 at the bottom of the trench 20. In particular, the electric field is more concentrated in the corner portion C of the bottom of the trench 20 closer to the element region 110 and facing the element region 110. In the semiconductor device shown in FIG. 1, in the inner region 121 close to the element region 110, the extending portion 221 of the trench 20 extends from the opening of the trench 20 onto the upper surface of the semiconductor substrate 10 with the insulating film interposed therebetween. Extending to the side. Thereby, as described below, the concentration of the electric field at the corner portion C can be relaxed.
　半導体装置をオフ状態又は逆バイアス状態にした場合に、トレンチ２０の側面及び底面に空乏層が生じる。ここで、トレンチ２０の素子領域側の側面はトレンチ２０の外側の側面よりも電界集中が生じやすい。特に、外側領域１２２よりも内側領域１２１のトレンチ２０で電界集中が生じやすい。内側領域１２１では、延在部２２１の下方の半導体基体１０内にも空乏層が生じるので、内側領域１２１においてトレンチ２０の素子領域１１０側の側面側における等電位面の間隔が広くなり、コーナー部Ｃでの電界の集中が緩和される。 When the semiconductor device is turned off or reverse biased, a depletion layer is formed on the side surface and the bottom surface of the trench 20. Here, the electric field concentration is more likely to occur on the side surface of the trench 20 on the element region side than on the side surface outside the trench 20. In particular, electric field concentration is more likely to occur in the trench 20 in the inner region 121 than in the outer region 122. In the inner region 121, since a depletion layer is also formed in the semiconductor substrate 10 below the extending part 221, the interval between the equipotential surfaces on the side surface side of the trench 20 in the inner region 121 on the element region 110 side is wide, and the corner part is formed. The concentration of the electric field at C is relaxed.
　図３及び図４に、半導体基体１０の電位分布と空乏層の状況をシミュレーションした結果の例を示す。図３は、延在部２２１が形成されない比較例のトレンチ２０の等電位面Ｓ１～Ｓ４と空乏層の状況を示している。図４は、延在部２２１を形成したトレンチ２０の等電位面Ｓ１～Ｓ４と空乏層の状況の例を示している。等電位面Ｓ１は、素子領域１１０に近い側の等電位面であり、等電位面Ｓ２～Ｓ４は等電位面Ｓ１よりも外側の等電位面である。図３と図４を比較して明らかなように、延在部２２１を形成したトレンチ２０では、等電位面の間隔がより広くなり、電界の集中がより緩和され、トレンチ２０の側面及び延在部２２１下方の半導体基体１０の上面付近で空乏層がより広がっている。その結果、半導体装置の耐圧が向上する。 3 and 4 show examples of results of simulation of the potential distribution of the semiconductor substrate 10 and the state of the depletion layer. FIG. 3 shows the equipotential surfaces S1 to S4 and the depletion layer of the trench 20 of the comparative example in which the extending portion 221 is not formed. FIG. 4 shows an example of a situation of equipotential surfaces S1 to S4 of the trench 20 in which the extension portion 221 is formed and the depletion layer. The equipotential surface S1 is an equipotential surface near the element region 110, and the equipotential surfaces S2 to S4 are equipotential surfaces outside the equipotential surface S1. As is clear from comparison between FIG. 3 and FIG. 4, in the trench 20 in which the extending portion 221 is formed, the equipotential surface spacing becomes wider, the concentration of the electric field is further alleviated, and the side surface and the extending portion of the trench 20 are extended. The depletion layer spreads near the upper surface of the semiconductor substrate 10 below the portion 221. As a result, the breakdown voltage of the semiconductor device is improved.
　なお、素子領域１１０に近いトレンチ２０ほど、電界が集中しやすい。このため、素子領域１１０に向かう方向に延在させる延在部２２１の長さＬを、素子領域１１０に近いトレンチ２０ほど長くしてもよい。また、素子領域１１０に近いトレンチ２０から延在する延在部２２１の長さＬが、外側領域１２２に近いトレンチ２０から延在する延在部２２１よりも長くなっていればよい。その中間の残りのトレンチ２０から延在する延在部２２１の長さＬは、例えば４μｍ、４μｍ、３．５μｍ、３μｍ、２．５μｍ、２μｍと、単数又は複数のトレンチ２０毎に段階的に素子領域１１０側のトレンチ２０から順に短くなっていてもよい。また、残りのトレンチ２０から延在する延在部２２１は一定の長さとしてもよい。 The electric field is more likely to concentrate in the trench 20 closer to the element region 110. Therefore, the length L of the extending portion 221 that extends in the direction toward the element region 110 may be increased as the trench 20 is closer to the element region 110. Further, the length L of the extension portion 221 extending from the trench 20 close to the element region 110 may be longer than the length L of the extension portion 221 extending from the trench 20 close to the outer region 122. The length L of the extending portion 221 extending from the remaining trench 20 in the middle thereof is, for example, 4 μm, 4 μm, 3.5 μm, 3 μm, 2.5 μm, 2 μm, and stepwise for each single or plural trenches 20. It may be shorter in order from the trench 20 on the element region 110 side. Further, the extending portion 221 extending from the remaining trench 20 may have a constant length.
　ところで、空乏層が半導体基体１０の外縁まで延伸すると、リーク電流が発生したり耐圧が低下したりするなどの問題が生じる。このため、図１に示した半導体装置では、周辺領域１２０の外側領域１２２に配置されたトレンチ２０については、導電体膜２２が半導体基体１０の上面に配置されていないことが望ましい。これにより、外側領域１２２では内側領域１２１のようには等電位面の間隔が広くなることがない。このため、空乏層が半導体基体１０の外縁まで延伸することが抑制される。 By the way, if the depletion layer extends to the outer edge of the semiconductor substrate 10, problems such as generation of leak current and reduction of breakdown voltage occur. Therefore, in the semiconductor device shown in FIG. 1, it is preferable that the conductor film 22 is not arranged on the upper surface of the semiconductor substrate 10 in the trench 20 arranged in the outer region 122 of the peripheral region 120. This prevents the equipotential surfaces from being widened in the outer region 122 as in the inner region 121. Therefore, the depletion layer is suppressed from extending to the outer edge of the semiconductor substrate 10.
　上記のように、素子領域１１０に近いために電界が集中しやすい内側領域１２１においてのみ、トレンチ２０の延在部２２１を形成することが好ましい。なお、周辺領域１２０の内側領域１２１と外側領域１２２の境界の位置は、半導体装置に要求される耐圧などに応じて設定することができる。延在部２２１を形成するトレンチ２０の本数が増えて内側領域１２１が外側に広がるほど、等電位面の間隔が広い領域が外側に延伸する。それにより、リーク電流が発生したり耐圧が低下したりするなどの信頼性の問題が生じる可能性がある。 As described above, it is preferable to form the extending portion 221 of the trench 20 only in the inner region 121 where the electric field is likely to be concentrated because it is close to the element region 110. The position of the boundary between the inner region 121 and the outer region 122 of the peripheral region 120 can be set according to the breakdown voltage required for the semiconductor device. As the number of trenches 20 forming the extending portion 221 increases and the inner region 121 expands outward, a region having a wide equipotential surface interval extends outward. As a result, there is a possibility that reliability problems such as generation of leakage current and reduction of breakdown voltage may occur.
　ここで、図１に示すように、隣接するトレンチ２０の配置間隔をトレンチピッチＰ１、隣接するトレンチ２０間の半導体基体１０の上面が露出した領域の幅をトレンチピラーＰ２と定義する。図５に、本発明者らがトレンチ比Ｐ１／Ｐ２と半導体装置の耐圧との関係を調査した結果を示す。図５に示すように、トレンチ比Ｐ１／Ｐ２が１．５を超える場合に耐圧が安定する。このため、トレンチ比Ｐ１／Ｐ２が１．５より小さい領域を内側領域１２１とする。これにより、内側領域１２１を広げすぎることなく半導体装置の耐圧を効果的に向上させることができる。 Here, as shown in FIG. 1, an arrangement interval between the adjacent trenches 20 is defined as a trench pitch P1, and a width of a region where the upper surface of the semiconductor substrate 10 between the adjacent trenches 20 is exposed is defined as a trench pillar P2. FIG. 5 shows the results of the investigation conducted by the present inventors on the relationship between the trench ratio P1/P2 and the breakdown voltage of the semiconductor device. As shown in FIG. 5, when the trench ratio P1/P2 exceeds 1.5, the breakdown voltage becomes stable. Therefore, the region where the trench ratio P1/P2 is smaller than 1.5 is defined as the inner region 121. As a result, the breakdown voltage of the semiconductor device can be effectively improved without expanding the inner region 121 too much.
　以上に説明したように、図１に示した半導体装置では、素子領域１１０に近い内側領域１２１に配置されたトレンチ２０において、導電体膜２２の一部である延在部２２１が半導体基体１０の上面の上に絶縁膜を介して延在する。これにより、半導体基体１０の等電位面の間隔を広げて空乏層の伸びを制御して、周辺領域１２０における電界の集中が緩和される。その結果、第１の実施形態に係る半導体装置によれば、素子領域１１０の周囲を囲むトレンチ２０の囲み数を増大させることなく、耐圧を向上できる。したがって、チップサイズの増大を抑制しつつ耐圧を向上した半導体装置を実現できる。また、内側領域１２１では、延在部２２１と延在部２２１下方の半導体基体１０との間に容量が生じ、延在部２２１がない時よりもトレンチ２０の内側に生じる容量が大きくなる。その結果、トレンチ２０の絶縁膜２１にかかる電圧を低下させることができる。これにより、半導体装置の信頼性も向上する。 As described above, in the semiconductor device shown in FIG. 1, in the trench 20 arranged in the inner region 121 close to the element region 110, the extending portion 221 that is a part of the conductor film 22 has the semiconductor substrate 10. It extends on the upper surface through an insulating film. This widens the equipotential surface of the semiconductor substrate 10 to control the extension of the depletion layer and alleviate the concentration of the electric field in the peripheral region 120. As a result, according to the semiconductor device of the first embodiment, the breakdown voltage can be improved without increasing the number of surrounding trenches 20 surrounding the element region 110. Therefore, it is possible to realize a semiconductor device having an improved breakdown voltage while suppressing an increase in chip size. Further, in the inner region 121, a capacitance is generated between the extending portion 221 and the semiconductor substrate 10 below the extending portion 221, and the capacitance generated inside the trench 20 is larger than that when the extending portion 221 is not provided. As a result, the voltage applied to the insulating film 21 of the trench 20 can be reduced. This also improves the reliability of the semiconductor device.
　＜変形例＞
　図１に示した半導体装置では、トレンチ２０の導電体膜２２の延在部２２１が、トレンチ２０の開口部から素子領域１１０に近い領域に向かって延在している。しかし、例えば、図６に示すように、トレンチ２０の開口部から素子領域１１０に近い領域に向かって延在した部分とトレンチ２０の開口部から半導体基体１０の外縁に近い領域に向かって延在した部分に延在部２２１を配置してもよい。或いは、図７に示すように、トレンチ２０の開口部から半導体基体１０の外縁に近い領域に向かって延在した部分のみに延在部２２１を配置してもよい。 <Modification>
In the semiconductor device shown in FIG. 1, the extending portion 221 of the conductor film 22 of the trench 20 extends from the opening of the trench 20 toward the region near the element region 110. However, for example, as shown in FIG. 6, a portion extending from the opening of the trench 20 toward the region near the element region 110 and a portion extending from the opening of the trench 20 toward the region near the outer edge of the semiconductor substrate 10. The extending portion 221 may be arranged at the portion. Alternatively, as shown in FIG. 7, the extending portion 221 may be arranged only in the portion extending from the opening of the trench 20 toward the region near the outer edge of the semiconductor substrate 10.
　（第２の実施形態）
　本発明の第２の実施形態に係る半導体装置は、図８に示すように、外側領域１２２よりも内側領域１２１において、トレンチ２０の溝の深さが浅い。つまり、内側領域１２１と外側領域１２２とでトレンチ２０の溝の深さが異なることが第１の実施形態と異なる点である。その他の構成については、図１に示す第１の実施形態と同様である。 (Second embodiment)
In the semiconductor device according to the second embodiment of the present invention, as shown in FIG. 8, the depth of the trench 20 is shallower in the inner region 121 than in the outer region 122. That is, the inner region 121 and the outer region 122 have different groove depths of the trench 20, which is a difference from the first embodiment. Other configurations are similar to those of the first embodiment shown in FIG.
　図８に示した半導体装置によれば、内側領域１２１において、トレンチ２０の溝の底部から、トレンチ２０の溝と接する第１半導体層１１と第２半導体層１２とのＰＮ接合面までの距離Ｔを短くできる。その結果、内側領域１２１のトレンチ２０の底部における等電位面の間隔が広がり、電界の集中を緩和できる。このため、半導体装置の耐圧を向上できる。 According to the semiconductor device shown in FIG. 8, in the inner region 121, the distance T from the bottom of the groove of the trench 20 to the PN junction surface of the first semiconductor layer 11 and the second semiconductor layer 12 which is in contact with the groove of the trench 20. Can be shortened. As a result, the interval between the equipotential surfaces at the bottom of the trench 20 in the inner region 121 becomes wider, and the concentration of electric field can be relaxed. Therefore, the breakdown voltage of the semiconductor device can be improved.
　内側領域１２１のトレンチ２０の溝の深さは、例えば４．０μｍ程度であり、トレンチ２０の溝の底部から溝の側面と接する第１半導体層１１と第２半導体層１２とのＰＮ接合面までの距離Ｔは０μｍから０．５μｍである。一方、外側領域１２２のトレンチ２０の溝の深さは、例えば４．５μｍ程度であり、トレンチ２０の溝の底部から溝の側面と接する第１半導体層１１と第２半導体層１２とのＰＮ接合面までの距離Ｔは０．５μｍから１．５μｍである。内側領域１２１と外側領域１２２とでトレンチ２０の溝の深さを異なるようにするためには、種々の方法を使用可能である。例えば、内側領域１２１のトレンチ２０の溝の幅を、外側領域１２２のトレンチ２０の溝の幅よりも狭くする。このような溝を形成するマスクを半導体基体１０上に設けて、内側領域１２１と外側領域１２２のトレンチ２０の溝を同じプロセス条件で同時に形成して、外側領域１２２よりも内側領域１２１においてトレンチ２０の溝を浅く形成することができる。なお、内側領域１２１のトレンチ２０の溝と外側領域１２２のトレンチ２０の溝を、プロセス条件の異なる別々の工程で形成してもよい。 The depth of the groove of the trench 20 in the inner region 121 is, for example, about 4.0 μm, and from the bottom of the groove of the trench 20 to the PN junction surface between the first semiconductor layer 11 and the second semiconductor layer 12 that is in contact with the side surface of the groove. The distance T is 0 to 0.5 μm. On the other hand, the depth of the groove of the trench 20 in the outer region 122 is, for example, about 4.5 μm, and the PN junction between the first semiconductor layer 11 and the second semiconductor layer 12 in contact with the side surface of the groove from the bottom of the groove of the trench 20. The distance T to the surface is 0.5 μm to 1.5 μm. Various methods can be used to make the groove depth of the trench 20 different between the inner region 121 and the outer region 122. For example, the width of the groove of the trench 20 in the inner region 121 is made narrower than the width of the groove of the trench 20 in the outer region 122. A mask for forming such a groove is provided on the semiconductor substrate 10, the grooves of the trench 20 in the inner region 121 and the outer region 122 are simultaneously formed under the same process condition, and the trench 20 is formed in the region 121 inside the outer region 122. The groove can be formed shallowly. The groove of the trench 20 in the inner region 121 and the groove of the trench 20 in the outer region 122 may be formed in different steps under different process conditions.
　また、ＦＥＴやＩＧＢＴなどを形成した素子領域１１０の半導体基体１０の上面側に形成されるベース領域などの第２導電型（ｐ型）の半導体領域の深さと第２半導体層１２の深さは、同じ深さとしてもよいし、異なる深さとしてもよい。例えば、素子領域１１０のベース領域などの第２導電型の半導体領域の深さがトレンチ２０の深さよりも浅い場合、素子領域１１０のベース領域などの第２導電型の半導体領域の深さよりも第２半導体層１２の深さを深くしてもよい。これにより、素子領域１１０の第２導電型の半導体領域の深さに依存せず、距離Ｔを適宜調整することができる。 Further, the depth of the second conductivity type (p-type) semiconductor region such as the base region formed on the upper surface side of the semiconductor substrate 10 of the element region 110 formed with the FET or the IGBT and the depth of the second semiconductor layer 12 are The depths may be the same or different. For example, when the depth of the second-conductivity-type semiconductor region such as the base region of the element region 110 is shallower than the depth of the trench 20, the depth of the second-conductivity-type semiconductor region such as the base region of the element region 110 is smaller than that of the second-conductivity-type semiconductor region. 2 The depth of the semiconductor layer 12 may be increased. Thus, the distance T can be adjusted as appropriate without depending on the depth of the second conductivity type semiconductor region of the element region 110.
　また、内側領域１２１のトレンチ２０の溝の深さと外側領域１２２のトレンチ２０の溝の深さをほぼ同じ深さとし、内側領域１２１の第２半導体層１２の深さを外側領域１２２の第２半導体層１２の深さよりも深くしてもよい。これにより、内側領域１２１のトレンチ２０の溝の深さと外側領域１２２のトレンチ２０の溝の深さがほぼ同じであっても、距離Ｔを適宜調整することができる。 The depth of the trench 20 in the inner region 121 and the depth of the trench 20 in the outer region 122 are set to be substantially the same, and the depth of the second semiconductor layer 12 in the inner region 121 is set to the second semiconductor in the outer region 122. It may be deeper than the depth of layer 12. Accordingly, even if the groove depth of the trench 20 in the inner region 121 and the groove depth of the trench 20 in the outer region 122 are substantially the same, the distance T can be appropriately adjusted.
　本発明の第２の実施形態に係る半導体装置によれば、チップサイズの増大を抑制しつつ耐圧を更に向上することができる。他は、第１の実施形態と実質的に同様であり、重複した記載を省略する。なお、より好ましい例として、第２の実施形態においても、第１の実施形態と同様に延在部２２１を有する構成で説明したが、第２の実施形態においては、延在部２２１を有さなくても電界の集中を緩和でき、半導体装置の耐圧を向上できる。 According to the semiconductor device of the second embodiment of the present invention, the breakdown voltage can be further improved while suppressing the increase in chip size. Others are substantially the same as those in the first embodiment, and duplicate description will be omitted. Note that, as a more preferable example, the second embodiment also has the configuration including the extending portion 221 as in the first embodiment, but the second embodiment does not include the extending portion 221. Even without it, the concentration of the electric field can be relaxed and the breakdown voltage of the semiconductor device can be improved.
　上記のように本発明は実施形態によって記載したが、この開示の一部をなす論述及び図面はこの発明を限定するものであると理解すべきではない。この開示から当業者には様々な代替実施形態、実施例及び運用技術が明らかとなろう。 Although the present invention has been described by the embodiments as described above, it should not be understood that the discussion and drawings forming a part of this disclosure limit the present invention. From this disclosure, various alternative embodiments, examples, and operation techniques will be apparent to those skilled in the art.
　本発明の半導体装置は、高い耐圧が要求される半導体装置を製造する製造業を含む電子機器産業に利用可能である。 The semiconductor device of the present invention can be used in the electronic equipment industry including the manufacturing industry that manufactures semiconductor devices that require high breakdown voltage.
　１０…半導体基体
　１１…第１半導体層
　１２…第２半導体層
　２０…トレンチ
　２１…絶縁膜
　２２…導電体膜
　２２１…延在部
　３０…保護膜
　１１０…素子領域
　１２０…周辺領域
　１２１…内側領域
　１２２…外側領域 DESCRIPTION OF SYMBOLS 10... Semiconductor substrate 11... 1st semiconductor layer 12... 2nd semiconductor layer 20... Trench 21... Insulating film 22... Conductor film 221... Extension part 30... Protective film 110... Element area|region 120... Peripheral area|region 121... Inside area 122 ...Outer area

Claims (6)

  1. 　素子領域と前記素子領域の周囲を囲む周辺領域が上面に定義された半導体基体を備え、
    　前記半導体基体の上面から膜厚方向に延伸する溝の内壁面に配置された絶縁膜、及び前記溝の内部で前記絶縁膜の上に配置された導電体膜をそれぞれ有する複数のトレンチが、前記素子領域の周囲を囲んで前記周辺領域に多重に配置され、
    　前記周辺領域は、
    　前記素子領域に近い内側領域と、
    　前記内側領域の周囲に位置する外側領域を有し、
    　隣接する前記トレンチに挟まれた前記半導体基体の幅は、前記外側領域よりも前記内側領域の方が広い
    　ことを特徴とする半導体装置。     An element region and a peripheral region surrounding the periphery of the element region are provided with a semiconductor substrate defined on an upper surface,
    A plurality of trenches each having an insulating film arranged on the inner wall surface of the groove extending from the upper surface of the semiconductor substrate in the film thickness direction, and a conductor film arranged on the insulating film inside the groove, Surrounding the periphery of the element region, are multiply arranged in the peripheral region,
    The peripheral area is
    An inner region close to the element region,
    An outer region located around the inner region,
    A semiconductor device characterized in that the width of the semiconductor substrate sandwiched between the adjacent trenches is wider in the inner region than in the outer region.
  2. 　隣接する前記トレンチの配置間隔をトレンチピッチＰ１、隣接する前記トレンチ間の前記半導体基体の上面が露出した領域の幅をトレンチピラーＰ２として、トレンチ比Ｐ１／Ｐ２が１．５より小さい領域が前記内側領域であることを特徴とする請求項１に記載の半導体装置。 A region where a trench ratio P1/P2 is smaller than 1.5 is defined as an inner side by defining an arrangement interval of the adjacent trenches as a trench pitch P1 and a width of a region between the adjacent trenches where an upper surface of the semiconductor substrate is exposed as a trench pillar P2. The semiconductor device according to claim 1, wherein the semiconductor device is a region.
  3. 　前記半導体基体が、第１導電型の第１半導体層の上に第２導電型の第２半導体層が積層された構造であり、
    　前記トレンチが、前記第２半導体層の上面から延伸して前記第１半導体層に達して形成され、
    　前記内側領域の前記トレンチの底部から前記第１半導体層と前記第２半導体層とのＰＮ接合面までの距離が、前記外側領域の前記トレンチの底部から前記第１半導体層と前記第２半導体層とのＰＮ接合面までの距離よりも小さいことを特徴とする請求項２に記載の半導体装置。     The semiconductor substrate has a structure in which a second conductive type second semiconductor layer is stacked on a first conductive type first semiconductor layer,
    The trench extends from the upper surface of the second semiconductor layer and reaches the first semiconductor layer;
    The distance from the bottom of the trench in the inner region to the PN junction surface of the first semiconductor layer and the second semiconductor layer is the distance from the bottom of the trench in the outer region to the first semiconductor layer and the second semiconductor layer. 3. The semiconductor device according to claim 2, wherein the distance is smaller than the distance to the PN junction surface with.
  4. 　前記内側領域に、前記トレンチの前記導電体膜と電気的に接続し、前記トレンチの開口部から前記素子領域に向かう延在部が前記半導体基体の上面の上に配置され、
    　前記外側領域には、前記トレンチの開口部から前記素子領域に向かう前記延在部が配置されていない、若しくは前記外側領域に配置された前記延在部の前記半導体基体の上面に沿った距離が前記内側領域に配置された前記延在部よりも短い
    　ことを特徴とする請求項２に記載の半導体装置。     In the inner region, electrically connected to the conductor film of the trench, the extending portion from the opening of the trench toward the element region is arranged on the upper surface of the semiconductor substrate,
    In the outer region, the extending portion from the opening of the trench toward the element region is not arranged, or the distance along the upper surface of the semiconductor substrate of the extending portion arranged in the outer region is The semiconductor device according to claim 2, wherein the semiconductor device is shorter than the extending portion arranged in the inner region.
  5. 　前記内側領域に前記トレンチが複数配置され、
    　前記内側領域において、前記素子領域に近い前記トレンチほど、前記延在部の前記半導体基体の上面に沿った距離が長いことを特徴とする請求項４に記載の半導体装置。     A plurality of the trenches are arranged in the inner region,
    The semiconductor device according to claim 4, wherein in the inner region, the closer the trench is to the element region, the longer the distance along the upper surface of the semiconductor substrate of the extending portion is.
  6. 　前記外側領域において、前記半導体基体の上面の上に前記延在部が配置されていないことを特徴とする請求項４に記載の半導体装置。 The semiconductor device according to claim 4, wherein the extending portion is not arranged on the upper surface of the semiconductor substrate in the outer region.
PCT/JP2018/046035 2018-12-14 2018-12-14 Semiconductor device WO2020121508A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007123570A (en) * 2005-10-28 2007-05-17 Toyota Industries Corp Semiconductor device
JP2008085086A (en) * 2006-09-27 2008-04-10 Toyota Industries Corp Semiconductor device
JP2009032728A (en) * 2007-07-24 2009-02-12 Sanken Electric Co Ltd Semiconductor device

Family Cites Families (2)

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US9484451B2 (en) * 2007-10-05 2016-11-01 Vishay-Siliconix MOSFET active area and edge termination area charge balance
JP2013055347A (en) 2012-11-08 2013-03-21 Sanken Electric Co Ltd Semiconductor device

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2007123570A (en) * 2005-10-28 2007-05-17 Toyota Industries Corp Semiconductor device
JP2008085086A (en) * 2006-09-27 2008-04-10 Toyota Industries Corp Semiconductor device
JP2009032728A (en) * 2007-07-24 2009-02-12 Sanken Electric Co Ltd Semiconductor device

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