JP2012156153A - Semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor device in which voltage resistance can be prevented from being lowered by avoiding generation of ununiform charge distribution between a surface protective film composed of SiOand a coating part composed of a thermosetting resin containing polysiloxane as a main component.SOLUTION: A semiconductor device comprises a surface protective film 16 composed of SiOand coating the surface of an SiC pn junction diode 10, a polyimide resin film 22 coating the surface protective film 16 (1 μm thick), and a coating part 23 composed of a silicon resin and coating the polyimide resin film 22. The polyimide resin film 22 exhibits high affinity to the SiOsurface protective film 16 and the coating part 23 composed of silicon resin. Since the polyimide resin film 22 forms a stable joint surface on the interface of the surface protective film 16 and the coating part 23, charge does not accumulate easily on the interface and the charge accumulated on the interface can be reduced.

Description

  The present invention relates to a semiconductor device including a semiconductor element made of a wide band gap semiconductor such as silicon carbide.

Conventionally, a SiO ₂ film is generally used as a surface protective film of a semiconductor element made of a wide band gap semiconductor such as silicon carbide. Further, when the semiconductor element is built in the module, a thermosetting insulating protective resin mainly composed of polysiloxane is applied to the surface.

By the way, since the affinity of the interface between the SiO ₂ film as the surface protective film and the thermosetting insulating protective resin mainly composed of the polysiloxane is not high, non-uniformity is caused due to accumulation of charges at the interface. There is a problem in that charge distribution occurs and voltage resistance is lowered.

SiO ₂ is a covalent bond crystal, and has a structure in which a frontal body structure centered on silicon is infinitely connected through oxygen atoms. A thermosetting resin mainly composed of polysiloxane is also a compound having a Si—O—Si bond (siloxane bond) and a skeleton of oxygen and oxygen. Both SiO ₂ and thermosetting resin containing polysiloxane as a main component have strong bonds in the main skeleton and high electrical insulation.

Although both SiO ₂ and thermosetting resin based on polysiloxane are basically compounds with silicon and oxygen as the skeleton, the surface stability is high, so the affinity of the interface boundary between the two is not good. Therefore, electric charges accumulate at the interface boundary under high voltage. Furthermore, this charge cannot move freely within the boundary interface, causing an uneven charge distribution at the interface boundary. This causes local electric field concentration, and particularly causes breakdown of the element during dynamic breakdown voltage recovery such as turn-off and recovery. Wide bandgap semiconductors such as SiC have a dielectric breakdown strength that is an order of magnitude greater than Si, and almost the same dielectric breakdown strength as SiO ₂ , so such wide bandgap semiconductors have this interface boundary instability. Elimination is a major issue.

JP 2009-212342 A Japanese Patent Laying-Open No. 2005-167035

Accordingly, an object of the present invention is to generate a non-uniform charge distribution between a surface protective film made of SiO ₂ and a coating part made of a thermosetting resin mainly composed of polysiloxane. It is an object of the present invention to provide a semiconductor device that can be avoided to prevent a decrease in voltage resistance.

In order to solve the above problems, a semiconductor device of the present invention includes a semiconductor element made of a wide gearup semiconductor,
A support on which the semiconductor element is mounted;
An electrical connection for electrically connecting the semiconductor element to an external device;
A surface protective film covering the upper surface of the semiconductor element and made of SiO ₂ ;
A polyimide resin film coated with the surface protective film and made of polyimide;
It is characterized by comprising at least a part of the polyimide resin film and the electrical connection part, and a covering part made of a thermosetting resin whose main component is polysiloxane while covering the side surface of the semiconductor element.

According to the semiconductor device of the present invention, the polyimide resin film made of the polyimide has a surface protective film made of SiO ₂ and a covering portion made of a thermosetting resin mainly composed of polysiloxane. High affinity. Therefore, the polyimide resin film forms a stable bonding surface at the boundary surface between the surface protective film and the covering portion. Thereby, it is difficult for electric charges to accumulate at the interface between the polyimide resin film and the surface protective film and the interface between the polyimide resin film and the covering portion, and the charge charged at the interface can be reduced. Therefore, non-uniform charge distribution can be suppressed under high voltage, especially during dynamic breakdown voltage recovery, local electric field concentration can be avoided, and breakdown of voltage resistance can be prevented to prevent device breakdown. Can do.

Polyimide is a general term for polymers containing imide bonds in repeating units. Usually, it refers to an aromatic polyimide in which aromatic compounds are directly linked by an imide bond. Aromatic polyimide has a conjugated structure via imide bonds between aromatics, so it has a strong molecular structure, and imide bonds have a strong intermolecular force. It has high thermal, mechanical and chemical properties. On the other hand, polyimide has a π bond in which electrons are directly shared between the p orbitals of two atoms. The π bond is weaker than the σ bond because it has a distance from the positive charge of the nucleus. Therefore, a stable joint surface is formed at the interface boundary with SiO ₂ or polysiloxane. This reduces the charge on the interface, suppresses non-uniform charge distribution at high voltage, especially during dynamic voltage recovery, avoids local electric field concentration, and destroys the device. Can be prevented.

  In the present invention, the thermosetting resin containing polysiloxane as a main component corresponds to a silicon resin.

In one embodiment of the semiconductor device, the thermosetting resin for producing the covering portion is
A silicon-containing curable composition containing the following component (A), component (B), component (D),
The said coating | coated part is the hardened | cured material which heat-cured the said silicon-containing curable composition, The linear expansion coefficient of the said hardened | cured material is 50-300 ppm / degreeC, It is characterized by the above-mentioned.

（上式(１)中、Ｒ^１〜Ｒ^７は、同一でも異なっていてもよく、炭素原子数１〜１２の飽和脂肪族炭化水素基、又は、飽和脂肪族炭化水素基で置換されていてもよい炭素原子数６〜１２の芳香族炭化水素基であり（但し、Ｒ^５及びＲ^６は同時に炭素原子数１〜１２の飽和脂肪族炭化水素基となることはない）、Ｒ^８は炭素原子数２〜４のアルキレン基であり、Ｚは炭素原子数２〜４のアルケニル基若しくはアルキニル基であり、ａは２〜７の数であり、ｂは１〜７の数であり、ｂを繰り返し数とする重合部分と、ａ−ｂを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。ｅは０〜３の数である。ｃ及びｄは、ｄ：ｃ＝１：１〜１：１００且つ全てのｃと全てのｄとの合計が１５以上となる数であって、且つ一般式（１）で表される珪素含有化合物の質量平均分子量を３０００〜１００万とする数である。また、ｃを繰り返し数とする重合部分と、ｄを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。）
(Ｂ)成分：下記一般式（２）で表される珪素含有化合物。

（上式(２)中、Ｒ^９〜Ｒ^１５は、同一でも異なっていてもよく、炭素原子数１〜１２の飽和脂肪族炭化水素基、又は、飽和脂肪族炭化水素基で置換されていてもよい炭素原子数６〜１２の芳香族炭化水素基であり（但し、Ｒ^１３及びＲ^１４は同時に炭素原子数１〜１２の飽和脂肪族炭化水素基となることはない）、Ｒ^１６は炭素原子数２〜４のアルキレン基であり、Ｈは炭素原子数２〜４のアルケニル基若しくはアルキニル基であり、ｆは２〜７の数であり、ｇは１〜７の数であり、ｇを繰り返し数とする重合部分と、ｆ−ｇを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。ｊは０〜３の数である。ｈ及びｉは、ｉ：ｈ＝１：１〜１：１００且つ全てのｈと全てのｉとの合計が１５以上となる数であって、且つ一般式（２）で表される珪素含有化合物の質量平均分子量を３０００〜１００万とする数である。また、ｈを繰り返し数とする重合部分と、ｉを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。）
(Ｄ)成分：白金系触媒である硬化反応触媒
この実施形態によれば、上記被覆部を作製する熱硬化性樹脂は、上記の（Ａ）成分および（Ｂ）成分を含有し、かつ硬化反応触媒である白金系触媒を含有する珪素含有硬化性組成物であり、さらに充填剤としてセラミックス粒子を配合してもよい。これにより、上記被覆部は高温(例えば２００℃以上)で使用してもクラック等が発生せず、高絶縁耐力を達成できる。 Component (A): A silicon-containing compound represented by the following general formula (1).

(In the above formula (1), R ^{1 to} R ⁷ may be the same or different and are substituted with a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated aliphatic hydrocarbon group. Or an aromatic hydrocarbon group having 6 to 12 carbon atoms (provided that R ⁵ and R ⁶ do not simultaneously become a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms), and R ⁸ is carbon. An alkylene group having 2 to 4 atoms, Z is an alkenyl group or alkynyl group having 2 to 4 carbon atoms, a is a number from 2 to 7, b is a number from 1 to 7, and b is The polymer moiety having the repeating number and the polymer moiety having the repeating number ab may be block-like or random, e is a number from 0 to 3. c and d are d: c = 1: 1 to 1: 100, and the sum of all c and all d is 15 or more, and The number average molecular weight of the silicon-containing compound represented by the general formula (1) is a number between 3000 and 1,000,000, and the polymerization portion where c is the number of repetitions and the polymerization portion where d is the number of repetitions are: It may be block or random.)
Component (B): A silicon-containing compound represented by the following general formula (2).

(In the above formula (2), R ^{9 to} R ¹⁵ may be the same or different and are substituted with a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated aliphatic hydrocarbon group. Or an aromatic hydrocarbon group having 6 to 12 carbon atoms (provided that R ¹³ and R ¹⁴ do not simultaneously become a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms), and R ¹⁶ is carbon. An alkylene group having 2 to 4 atoms, H is an alkenyl group or alkynyl group having 2 to 4 carbon atoms, f is a number from 2 to 7, g is a number from 1 to 7, and g is The polymerization part having the number of repetitions and the polymerization part having the number of repetitions of f-g may be in the form of blocks or random, j is a number from 0 to 3. h and i are i: h = 1: 1 to 1: 100 and the sum of all h and all i is 15 or more In addition, the silicon-containing compound represented by the general formula (2) has a mass average molecular weight of 3000 to 1,000,000, a polymer part having h as a repeat number, and a polymer part having i as a repeat number. And may be block or random.)
(D) Component: Curing Reaction Catalyst that is a Platinum-Based Catalyst According to this embodiment, the thermosetting resin for producing the coating portion contains the above-mentioned (A) component and (B) component, and the curing reaction It is a silicon-containing curable composition containing a platinum-based catalyst that is a catalyst, and may further contain ceramic particles as a filler. Thereby, even if it uses the said coating | coated part at high temperature (for example, 200 degreeC or more), a crack etc. do not generate | occur | produce and can achieve high dielectric strength.

  In one embodiment, the semiconductor element is made of a silicon carbide semiconductor.

  According to this embodiment, since the semiconductor element is made of a silicon carbide semiconductor, durability can be improved particularly under use conditions at high temperatures.

According to the semiconductor device of the present invention, the polyimide resin film made of polyimide which covers the surface protective film and is covered with the covering portion is mainly composed of the surface protective film made of SiO ₂ and polysiloxane. Affinity with the coating part made of thermosetting resin is high. Therefore, the polyimide resin film forms a stable bonding surface at the boundary surface between the surface protective film and the covering portion. Thereby, it is difficult for electric charges to accumulate at the interface between the polyimide resin film and the surface protective film and the interface between the polyimide resin film and the covering portion, and the charge charged at the interface can be reduced. Therefore, non-uniform charge distribution can be suppressed under high voltage, especially during dynamic breakdown voltage recovery, local electric field concentration can be avoided, and breakdown of voltage resistance can be prevented to prevent device breakdown. Can do.

It is sectional drawing which shows the semiconductor device provided with the pin diode which is embodiment of the semiconductor device of this invention. It is sectional drawing which shows typically electric potential distribution when a reverse direction voltage is applied to the said pin diode. It is a fragmentary sectional view which shows the equipotential line in the location of the surface protective film, the polyimide resin film, and the coating | coated part which were laminated | stacked sequentially on the pin diode at the time of the said reverse voltage application. It is sectional drawing which shows typically electric potential distribution when a reverse voltage is applied in the comparative example in which the surface protective film and the coating | coated part were laminated | stacked in order on the pin diode. It is sectional drawing which shows typically the electric potential distribution in the transient state of the voltage in the said comparative example.

  Hereinafter, the present invention will be described in detail with reference to the illustrated embodiments.

  FIG. 1 is a cross-sectional view of an embodiment of a semiconductor device of the present invention. This embodiment includes a SiC pn junction diode (pin diode) 10 as a semiconductor element. The SiC pn junction diode 10 is placed on the upper surface 1A of the copper support 1.

The SiC pn junction diode 10 has an n-type SiC substrate 11 and an n-type SiC drift layer 12 formed by epitaxial growth on the n-type SiC substrate 11. As an example, the n-type SiC substrate 11 has a carrier density of 8 × 10 ¹⁸ cm ⁻³ and a thickness of 400 μm. For example, the n-type SiC drift layer 12 has a donor density of 5 × 10 ¹³ cm ⁻³ and a film thickness of 300 μm.

The SiC pn junction diode 10 has a p-type SiC anode layer 13 formed on the n-type SiC drift layer 12. As an example, the p-type SiC anode layer 13 has an acceptor density of 5 × 10 ¹⁷ cm ⁻³ and a film thickness of 2 μm.

The p-type SiC anode layer 13 is processed into a mesa structure by removing both ends by reactive ion etching (RIE). As an etching gas in this RIE, CF ₄ (carbon tetrafluoride) and O ₂ were used, and etching was performed to a depth of about 2 μm by a plasma processing apparatus under conditions of a pressure of 5 Pa and a high frequency power of 260 W. Further, as a mask material at this time, a SiO ₂ film (thickness 10 μm) deposited by CVD was used.

Next, a p-type JTE (junction termination extension) 15 having a width of 250 μm and a depth of 0.7 μm was provided on the mesa bottom in order to alleviate electric field concentration at the bottom of the mesa formed by etching. This p-type JTE15 was formed by Al ion implantation. The energy of the Al ion implantation is changed in six steps between 30 to 450 keV, and the total dose is 1.2 × 10 ¹³ cm ⁻² . In addition, when the p-type JTE 15 was formed, the JTE 15 injection layer was designed to have a box profile. Ion implantation was all performed at room temperature, and graphite (thickness 5 μm) was used as a mask for ion implantation. Heat treatment for activating the implanted ions was performed in an argon gas atmosphere at 1700 ° C. for 3 minutes. In addition, the code | symbol 14 of FIG. 1 is an n-type channel stopper.

In addition, this embodiment includes a surface protective film 16 made of SiO ₂ , and this surface protective film 16 covers the upper surface of the SiC pn junction diode 10, but an anode electrode 18 described later is formed. It is not formed in a region on the upper surface of the p-type anode layer 13. In this embodiment, as an example, the thickness of the surface protective film 16 is 1 μm, but the thickness of the surface protective film 16 may be 1 μm or more or less than 1.

  Further, Ni (thickness 350 nm) is formed on the lower surface of the n-type SiC substrate 11 to form the cathode electrode 17. In addition, Ti (titanium: 350 nm thick) and Al (aluminum: 100 nm thick) films are deposited on the P-type anode layer 13 to form the anode electrode 18. The anode electrode 18 is composed of a Ti layer and an Al layer.

  A bonding wire 21 made of aluminum, gold, copper or the like is connected to the anode electrode 18. The bonding wire 21 is an electrical connection part for electrically connecting the SiC pn junction diode 10 to an external device.

  Further, the cathode electrode 17 is attached to the copper support 1 constituting the package using gold-based solder such as gold silicon, gold tin, and gold germanium or other high-temperature solder while maintaining electrical connection. .

Further, a polyimide resin film 22 is formed so as to cover the surface protective film 16 made of the SiO ₂ . In this embodiment, as an example, the thickness of the polyimide resin film 22 is 2 μm. However, the thickness of the polyimide resin film 22 may be 1 μm or 3 μm, and can be set in the range of 10 nm to 10 μm. It is not limited to.

  A covering portion 23 is formed so as to cover the polyimide resin film 22, the anode electrode 18, a part of the bonding wire 21, the side surface of the SiC pn junction diode 10, and the upper surface 1 </ b> A of the support 1. The covering portion 23 is made of a thermosetting resin whose main component is polysiloxane. In this embodiment, a thermosetting resin mainly composed of polysiloxane, which will be described in detail below, is used as the thermosetting resin for producing the covering portion 23, but other silicon resins are used. Also good.

  More specifically, in this embodiment, the silicon-containing curable composition used as the covering portion 23 is formed as an insulating ceramic to the silicon-containing curable composition synthesized by the synthesis step 1 to the synthesis step 5 described below. Alumina fine particles having a particle size of 20 μm are blended at a volume filling rate of 5%. The covering portion 23 is obtained by curing reaction of this silicon-containing curable composition at 200 ° C. for 6 hours. Moreover, the linear expansion coefficient of the said silicon-containing curable composition after the said hardening is 300 ppm / degreeC. In the synthesis steps 1 to 5, “parts” represents parts by weight.

  [Synthesis step 1] 90 parts of dichlorodimethylsilane and 9 parts of dichlorodiphenylsilane were mixed and dropped into a mixture of 100 parts of ion-exchanged water, 50 parts of toluene and 450 parts of 48% aqueous sodium hydroxide, Polymerization was carried out at 5 ° C. for 5 hours. The obtained reaction solution was washed with 500 parts of ion exchange water, and then this toluene solution was dehydrated, 20 parts of pyridine was added, 20 parts of dimethylchlorosilane was further added thereto, and the mixture was stirred at 70 ° C. for 30 minutes. Then, after washing with 100 parts of ion exchange water, the solvent was distilled off under reduced pressure at 150 ° C. Next, it was washed with 100 parts of acetonitrile, and then the solvent was distilled off under reduced pressure at 70 ° C. to obtain a chain polysiloxane compound (HSi-1). The molecular weight by GPC of the chain polysiloxane compound (HSi-1) was Mw = 20,000.

  [Synthesis Step 2] 100 parts of the acyclic polysiloxane compound (HSi-1) obtained in Synthesis Step 1 above is dissolved in 200 parts of toluene, 0.003 part of platinum-carbonylvinylmethyl complex as a platinum-based catalyst, and unsaturated 10 parts of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, which is a cyclic polysiloxane compound having a bond, was added and reacted at 105 ° C. for 2 hours. The solvent was distilled off under reduced pressure at 70 ° C. and then washed with 100 parts of acetonitrile. Thereafter, the solvent was distilled off under reduced pressure at 70 ° C. to obtain a silicon-containing compound (VSi-1). The silicon-containing compound (VSi-1) is a compound corresponding to the general formula (1), and as a result of analysis by GPC, Mw = 22,000.

  [Synthesis Step 3] 90 parts of dichlorodimethylsilane and 9 parts of dichlorodiphenylsilane were mixed and dropped into a mixture of 100 parts of ion exchange water, 50 parts of toluene and 450 parts of 48% aqueous sodium hydroxide, Polymerization was carried out at 5 ° C. for 5 hours. The obtained reaction solution was washed with 500 parts of ion exchange water, and then this toluene solution was dehydrated, 20 parts of pyridine was added, 20 parts of dimethylvinylchlorosilane was further added, and the mixture was stirred at 70 ° C. for 30 minutes. Then, after washing with 100 parts of ion exchange water, the solvent was distilled off under reduced pressure at 150 ° C. Next, it was washed with 100 parts of acetonitrile, and then the solvent was distilled off under reduced pressure at 70 ° C. to obtain a chain polysiloxane compound (VSi-2) having an unsaturated bond. The molecular weight by GPC of the chain polysiloxane compound (VSi-2) having an unsaturated bond was Mw = 20,000.

  [Synthesis Step 4] 100 parts of an acyclic polysiloxane compound (VSi-2) having an unsaturated bond obtained in Synthesis Step 1 above is dissolved in 200 parts of toluene, and a platinum-carbonylvinylmethyl complex 0.003 as a platinum catalyst. And 10 parts of 1,3,5,7-tetramethylcyclotetrasiloxane, which is a cyclic polysiloxane compound, were added and reacted at 105 ° C. for 2 hours. The solvent was distilled off under reduced pressure at 70 ° C. and then washed with 100 parts of acetonitrile. Thereafter, the solvent was distilled off under reduced pressure at 70 ° C. to obtain a silicon-containing compound (HSi-2). The silicon-containing compound (HSi-2) is a compound corresponding to the general formula (2), and the molecular weight by GPC was Mw = 22,000.

  [Synthesis step 5] 50 parts of the silicon-containing compound (VSi-1) obtained in the synthesis step 2 as the component (A) and the silicon-containing compound (HSi-2) obtained in the synthesis step 4 as the component (B) The silicon-containing curable composition was obtained by mixing 50 parts with 0.005 part of a platinum-carbonylvinylmethyl complex which is a platinum-based catalyst as component (D).

  It has been experimentally confirmed that the silicon-containing polymers (A) and (B) contained in the silicon-containing curable composition can employ the following compositions.

（上式(１)中、Ｒ^１〜Ｒ^７は、同一でも異なっていてもよく、炭素原子数１〜１２の飽和脂肪族炭化水素基、又は、飽和脂肪族炭化水素基で置換されていてもよい炭素原子数６〜１２の芳香族炭化水素基であり（但し、Ｒ^５及びＲ^６は同時に炭素原子数１〜１２の飽和脂肪族炭化水素基となることはない）、Ｒ^８は炭素原子数２〜４のアルキレン基であり、Ｚは炭素原子数２〜４のアルケニル基若しくはアルキニル基であり、ａは２〜７の数であり、ｂは１〜７の数であり、ｂを繰り返し数とする重合部分と、ａ−ｂを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。ｅは０〜３の数である。ｃ及びｄは、ｄ：ｃ＝１：１〜１：１００且つ全てのｃと全てのｄとの合計が１５以上となる数であって、且つ一般式（１）で表される珪素含有化合物の質量平均分子量を３０００〜１００万とする数である。また、ｃを繰り返し数とする重合部分と、ｄを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。）
(Ｂ)成分：下記一般式（２）で表される珪素含有化合物。

（上式(２)中、Ｒ^９〜Ｒ^１５は、同一でも異なっていてもよく、炭素原子数１〜１２の飽和脂肪族炭化水素基、又は、飽和脂肪族炭化水素基で置換されていてもよい炭素原子数６〜１２の芳香族炭化水素基であり（但し、Ｒ^１３及びＲ^１４は同時に炭素原子数１〜１２の飽和脂肪族炭化水素基となることはない）、Ｒ^１６は炭素原子数２〜４のアルキレン基であり、Ｈは炭素原子数２〜４のアルケニル基若しくはアルキニル基であり、ｆは２〜７の数であり、ｇは１〜７の数であり、ｇを繰り返し数とする重合部分と、ｆ−ｇを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。ｊは０〜３の数である。ｈ及びｉは、ｉ：ｈ＝１：１〜１：１００且つ全てのｈと全てのｉとの合計が１５以上となる数であって、且つ一般式（２）で表される珪素含有化合物の質量平均分子量を３０００〜１００万とする数である。また、ｈを繰り返し数とする重合部分と、ｉを繰り返し数とする重合部分とは、ブロック状であってもランダム状であってもよい。）
(Ｄ)成分：白金系触媒である硬化反応触媒
(Ｆ)成分：セラミックス粒子
また、上記被覆部２３をなす珪素含有硬化性組成物が含有するセラミックス粒子の粒径は１〜５０μｍが好ましく、５〜２５μｍがより好ましい。また、上記珪素含有硬化性組成物に占めるセラミックス粒子の体積充填率は０〜４０％が好ましく、５％以下がより好ましい。これにより、上記珪素含有硬化性組成物を硬化させてなる硬化物の線膨張係数を５〜３００ｐｐｍ/℃にすることができる。なお、上記被覆部２３をなす珪素含有硬化性組成物を硬化させてなる硬化物の線膨張係数を５０ｐｐｍ/℃より小さくすると、ポリイミド樹脂膜２２との密着性が悪くなる。なお、上記珪素含有硬化性組成物にセラミックス粒子を添加してもしなくてもよく、上記珪素含有硬化性組成物に占めるセラミックス粒子の体積充填率は、０％から７０％の範囲で設定可能であり、上記セラミックス粒子の体積充填率は、５％以下とすることが望ましい。また、上記珪素含有硬化性組成物を硬化させてなる硬化物の線膨張係数は３００ｐｐｍ/℃以下とすればよい。 Silicon-containing polymer (A) component: The following (A) component: A silicon-containing compound represented by the following general formula (1).

(In the above formula (1), R ^{1 to} R ⁷ may be the same or different and are substituted with a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated aliphatic hydrocarbon group. Or an aromatic hydrocarbon group having 6 to 12 carbon atoms (provided that R ⁵ and R ⁶ do not simultaneously become a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms), and R ⁸ is carbon. An alkylene group having 2 to 4 atoms, Z is an alkenyl group or alkynyl group having 2 to 4 carbon atoms, a is a number from 2 to 7, b is a number from 1 to 7, and b is The polymer moiety having the repeating number and the polymer moiety having the repeating number ab may be block-like or random, e is a number from 0 to 3. c and d are d: c = 1: 1 to 1: 100, and the sum of all c and all d is 15 or more, and The number average molecular weight of the silicon-containing compound represented by the general formula (1) is a number between 3000 and 1,000,000, and the polymerization portion where c is the number of repetitions and the polymerization portion where d is the number of repetitions are: It may be block or random.)
Component (B): A silicon-containing compound represented by the following general formula (2).

(In the above formula (2), R ^{9 to} R ¹⁵ may be the same or different and are substituted with a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated aliphatic hydrocarbon group. Or an aromatic hydrocarbon group having 6 to 12 carbon atoms (provided that R ¹³ and R ¹⁴ do not simultaneously become a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms), and R ¹⁶ is carbon. An alkylene group having 2 to 4 atoms, H is an alkenyl group or alkynyl group having 2 to 4 carbon atoms, f is a number from 2 to 7, g is a number from 1 to 7, and g is The polymerization part having the number of repetitions and the polymerization part having the number of repetitions of f-g may be in the form of blocks or random, j is a number from 0 to 3. h and i are i: h = 1: 1 to 1: 100 and the sum of all h and all i is 15 or more In addition, the silicon-containing compound represented by the general formula (2) has a mass average molecular weight of 3000 to 1,000,000, a polymer part having h as a repeat number, and a polymer part having i as a repeat number. And may be block or random.)
Component (D): a curing reaction catalyst that is a platinum-based catalyst
Component (F): Ceramic particles The particle size of the ceramic particles contained in the silicon-containing curable composition forming the covering portion 23 is preferably 1 to 50 μm, and more preferably 5 to 25 μm. Moreover, 0-40% is preferable and the volume filling rate of the ceramic particle which occupies for the said silicon-containing curable composition has more preferable 5% or less. Thereby, the linear expansion coefficient of the hardened | cured material formed by hardening | curing the said silicon-containing curable composition can be 5-300 ppm / degreeC. If the linear expansion coefficient of the cured product obtained by curing the silicon-containing curable composition forming the covering portion 23 is less than 50 ppm / ° C., the adhesion with the polyimide resin film 22 is deteriorated. The ceramic particles may or may not be added to the silicon-containing curable composition, and the volume filling rate of the ceramic particles in the silicon-containing curable composition can be set in the range of 0% to 70%. In addition, the volume filling rate of the ceramic particles is desirably 5% or less. Further, the linear expansion coefficient of a cured product obtained by curing the silicon-containing curable composition may be 300 ppm / ° C. or less.

  Moreover, the gas-barrier property of the said silicon-containing curable composition improves because the silicon-containing curable composition which comprises the said coating | coated part 23 contains insulating ceramic fine particles. That is, the silicon-containing curable composition is less susceptible to oxidative degradation.

Moreover, as an example of a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms represented by R ^{1 to} R ⁷ and R ^{9 to} R ¹⁵ in the general formulas (1) and (2), methyl , Ethyl, propyl, isopropyl, butyl, sec-butyl, tert-butyl, isobutyl, amyl, isoamyl, tert-amyl, hexyl, 2-hexyl, 3-hexyl, cyclohexyl, 1-methylcyclohexyl, heptyl, 2-heptyl, Examples include 3-heptyl, isoheptyl, tertiary heptyl, n-octyl, isooctyl, tertiary octyl, 2-ethylhexyl, nonyl, isononyl, decyl, dodecyl and the like.

In the general formulas (1) and (2), the aromatic hydrocarbon group having 6 to 12 carbon atoms that may be substituted with a saturated aliphatic hydrocarbon group represented by R ⁵ or R ¹³ is: The total number of carbon atoms including the saturated aliphatic hydrocarbon group which is a substituent is 6 to 12. As the saturated aliphatic hydrocarbon group which is a substituent, for example, among the saturated aliphatic hydrocarbon groups exemplified above, those capable of satisfying the above-mentioned number of carbon atoms can be adopted. As an example, phenyl, Naphthyl, 2-methylphenyl, 3-methylphenyl, 4-methylphenyl, 3-isopropylphenyl, 4-isopropylphenyl, 4-butylphenyl, 4-isobutylphenyl, 4-tert-butylphenyl, 4-hexylphenyl, 4 -Cyclohexylphenyl, 2,3-dimethylphenyl, 2,4-dimethylphenyl, 2,5-dimethylphenyl, 2,6-dimethylphenyl, 3,4-dimethylphenyl, 3,5-dimethylphenyl, cyclohexylphenyl, biphenyl 2,4,5-trimethylphenyl and the like.

Moreover, as an alkylene group having 2 to 4 carbon atoms represented by R ⁸ and R ¹⁶ in the above general formulas (1) and (2), for example, —CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ —, —CH ₂ CH ₂ CH ₂ CH ₂ —, —CH (CH ₃ ) CH ₂ —, —CH ₂ CH (CH ₃ ) — and the like can be mentioned.

In addition, as an example of the alkenyl group having 2 to 4 carbon atoms represented by Z and H in the general formulas (1) and (2), CH ₂ = CH-, CH ₂ = CH-CH _{2 -, CH 2 = CH-} CH 2 -CH 2 -, CH 2 = C (CH 3) -, CH 2 = C (CH 3) -CH 2 -, CH 2 = CH-CH (CH 3) - , etc. Is mentioned.

上記一般式(１)，(２)中のＲ^１〜Ｒ^７，Ｒ^９〜Ｒ^１５において、炭素原子数１〜１２の飽和脂肪族炭化水素基の割合を大きくすると、得られる硬化物の可撓性が向上し、飽和脂肪族炭化水素基で置換されていてもよい炭素原子数６〜１２の芳香族炭化水素基の割合を大きくすると、得られる硬化物の耐熱性及び硬度が向上する。該飽和脂肪族炭化水素基と該芳香族炭化水素の割合は、硬化物に求められる物性により任意に設定することができる。好ましい割合（数）は、該飽和脂肪族炭化水素基：該芳香族炭化水素が１００：１〜１：２であり、２０：１〜１：１がより好ましい。また、炭素原子数１〜１２の飽和脂肪族炭化水素基としては、耐熱性が良好であるのでメチル基が好ましく、飽和脂肪族炭化水素基で置換されていてもよい炭素原子数６〜１２の芳香族炭化水素基としては、耐熱性が良好であるのでフェニル基が好ましい。 Examples of the alkynyl group having 2 to 4 carbon atoms represented by Z and H in the general formulas (1) and (2) include the following groups.

In R ^{1 to} R ⁷ and R ^{9 to} R ¹⁵ in the general formulas (1) and (2), when the ratio of the saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms is increased, the resulting cured product can be obtained. Flexibility is improved, and when the proportion of the aromatic hydrocarbon group having 6 to 12 carbon atoms which may be substituted with a saturated aliphatic hydrocarbon group is increased, the heat resistance and hardness of the obtained cured product are improved. The ratio of the saturated aliphatic hydrocarbon group and the aromatic hydrocarbon can be arbitrarily set depending on the physical properties required for the cured product. A preferable ratio (number) of the saturated aliphatic hydrocarbon group: the aromatic hydrocarbon is 100: 1 to 1: 2, and 20: 1 to 1: 1 is more preferable. The saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms is preferably a methyl group because of good heat resistance, and has 6 to 12 carbon atoms which may be substituted with a saturated aliphatic hydrocarbon group. As the aromatic hydrocarbon group, a phenyl group is preferred because of good heat resistance.

In the general formulas (1) and (2), R ³ , R ¹¹ and R ⁴ , R ¹² are a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms, particularly a methyl group, and R ⁵ , It is preferable that at least one of R ¹³ and R ⁶ , R ¹⁴ is an aromatic hydrocarbon group having 1 to 12 carbon atoms which may be substituted with a saturated aliphatic hydrocarbon group, particularly a phenyl group.

  The silicon-containing compound has a mass average molecular weight of 3,000 to 1,000,000. If it is less than 3000, the resulting cured product has insufficient heat resistance, and if it is greater than 1 million, the viscosity increases and hinders handling. The mass average molecular weight is preferably 5,000 to 500,000, and more preferably 10,000 to 100,000.

  The silicon-containing compound is not particularly limited by the production method, and can be produced by applying a known reaction.

  According to this embodiment, the thermosetting resin for producing the covering portion 23 contains the above-mentioned components (A) and (B) and contains a platinum-based catalyst that is a curing reaction catalyst. Ceramic particles are blended as a filler in the conductive composition. Thereby, even if it uses the said coating | coated part 23 at high temperature (for example, 200 degreeC or more), a crack etc. do not generate | occur | produce and can achieve high dielectric strength.

  FIG. 2 shows an image of potential distribution when a reverse voltage V is applied between the bonding wire 21 and the support 1 in the embodiment. In FIG. 2, L (V) is an equipotential line of potential V, L (0) is an equipotential line of potential 0, and between this equipotential lines L (0) and L (V) A plurality of equipotential lines corresponding to the potential between the potential 0 and the potential V are drawn.

3 is an enlarged view of the portion of the pin diode 10 shown in FIG. 2 where the p-type JTE (junction termination extension) 15, the SiO ₂ surface protection film 16, the polyimide resin film 22, and the covering portion 23 are laminated. As shown. As shown in FIG. 3, in the laminated portion, each equipotential line L extends substantially straight without being bent. As described above, the polyimide resin film 22 forms a stable bonding surface at the boundary surface S1 with the SiO ₂ surface protective film 16 and the boundary surface S2 with the covering portion 23. Accordingly, the electric charges freely move at both the interfaces S1 and S2, and the electric charges hardly accumulate at both the interfaces S1 and S2 even in a voltage transient state, so that each equipotential line L can be maintained in a substantially straight state without bending. Thereby, local concentration of the electric field can be avoided, a decrease in the voltage resistance can be prevented, and the element can be prevented from being destroyed.

On the other hand, FIG. 4 shows a partially enlarged view of a comparative example in which the covering portion 23 is formed directly on the SiO ₂ surface protective film 16 and does not have the polyimide resin film 22. Since the affinity of the interface S11 between the SiO ₂ surface protective film 16 and the covering portion 23 containing polysiloxane as a main component is not good, electric charges are difficult to move freely at the interface S11. Therefore, in the voltage transient state, as shown in FIG. 5, charges accumulate at the interface S11, and the presence of this charge causes the equipotential line L to bend as shown by the solid line Lx. For this reason, the electric field concentrates locally in the SiC at the location Z indicated by the arrow, leading to a decrease in withstand voltage, leading to destruction of the element.

On the other hand, in this embodiment, a polyimide resin film 22 is formed between the SiO ₂ surface protective film 16 and the covering portion 23, and the polyimide resin film 22 is composed of the SiO ₂ surface protective film 16 and the poly Affinity with the coating part 23 made of a thermosetting resin mainly composed of siloxane is high. Therefore, the polyimide resin film 22 forms a stable bonding surface at the boundary surface between the SiO ₂ surface protective film 16 and the covering portion 23. Thereby, it is difficult for electric charges to accumulate at the interface between the polyimide resin film 22 and the SiO ₂ surface protective film 16 and the interface between the polyimide resin film 22 and the covering portion 23, and the charge charged at the interface can be reduced. . Therefore, non-uniform charge distribution can be suppressed under high voltage, particularly during dynamic breakdown voltage recovery, local electric field concentration can be avoided, and device breakdown can be prevented.

  The SiC pn diode of the above-described embodiment is used by being incorporated in a power control device such as an inverter, for example, in the home appliance field, the industrial field, a vehicle field such as an electric vehicle, and a power system field such as power transmission. By incorporating the SiC pn diode of the above embodiment into the power control device, not only element destruction can be prevented, but also loss during energization can be suppressed, enabling large current energization and improving device reliability. be able to.

  In the above embodiment, an example of a SiC pn diode using SiC as a bipolar semiconductor device using a wide gap semiconductor material has been described. However, the bipolar semiconductor device may be another bipolar semiconductor device such as GTO or IGBT. May be. The present invention can be applied not only to bipolar semiconductor devices but also to unipolar semiconductor devices. In addition to SiC, other wide gap semiconductor materials such as diamond and gallium nitride may be used as the wide gap semiconductor material.

DESCRIPTION OF SYMBOLS 1 Support body 1A Upper surface 10 SiC pn junction diode 11 n-type SiC substrate 12 n-type SiC drift layer 12
13 p-type SiC anode layer 14 n-type channel stopper 15 p-type JTE (junction termination extension)
16 SiO ₂ surface protective film 17 Cathode electrode 18 Anode electrode 21 Bonding wire 22 Polyimide resin film 23 Covering portion

Claims (3)

A semiconductor element made of a wide gearup semiconductor,
A support on which the semiconductor element is mounted;
An electrical connection for electrically connecting the semiconductor element to an external device;
A surface protective film covering the surface of the semiconductor element and made of a SiO ₂ film;
A polyimide resin film coated with the surface protective film and made of polyimide;
A semiconductor device comprising: the polyimide resin film and at least a part of the electrical connection portion; and a covering portion that covers a side surface of the semiconductor element and is made of a thermosetting resin having polysiloxane as a main component. . The semiconductor device according to claim 1,
The thermosetting resin for producing the covering portion is
A silicon-containing curable composition containing the following component (A), component (B), component (D),
The said coating | coated part is the hardened | cured material which heat-cured the said silicon-containing curable composition, The linear expansion coefficient of the said hardened | cured material is 50-300 ppm / degreeC, It is characterized by the above-mentioned.
Component (A): A silicon-containing compound represented by the following general formula (1).

(In the above formula (1), R ^{1 to} R ⁷ may be the same or different and are substituted with a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated aliphatic hydrocarbon group. Or an aromatic hydrocarbon group having 6 to 12 carbon atoms (provided that R ⁵ and R ⁶ do not simultaneously become a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms), and R ⁸ is carbon. An alkylene group having 2 to 4 atoms, Z is an alkenyl group or alkynyl group having 2 to 4 carbon atoms, a is a number from 2 to 7, b is a number from 1 to 7, and b is The polymer moiety having the repeating number and the polymer moiety having the repeating number ab may be block-like or random, e is a number from 0 to 3. c and d are d: c = 1: 1 to 1: 100, and the sum of all c and all d is 15 or more, and The number average molecular weight of the silicon-containing compound represented by the general formula (1) is a number between 3000 and 1,000,000, and the polymerization portion where c is the number of repetitions and the polymerization portion where d is the number of repetitions are: It may be block or random.)
Component (B): A silicon-containing compound represented by the following general formula (2).

(In the above formula (2), R ^{9 to} R ¹⁵ may be the same or different and are substituted with a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms or a saturated aliphatic hydrocarbon group. Or an aromatic hydrocarbon group having 6 to 12 carbon atoms (provided that R ¹³ and R ¹⁴ do not simultaneously become a saturated aliphatic hydrocarbon group having 1 to 12 carbon atoms), and R ¹⁶ is carbon. An alkylene group having 2 to 4 atoms, H is an alkenyl group or alkynyl group having 2 to 4 carbon atoms, f is a number from 2 to 7, g is a number from 1 to 7, and g is The polymerization part having the number of repetitions and the polymerization part having the number of repetitions of f-g may be in the form of blocks or random, j is a number from 0 to 3. h and i are i: h = 1: 1 to 1: 100 and the sum of all h and all i is 15 or more In addition, the silicon-containing compound represented by the general formula (2) has a mass average molecular weight of 3000 to 1,000,000, a polymer part having h as a repeat number, and a polymer part having i as a repeat number. And may be block or random.)
Component (D): a curing reaction catalyst that is a platinum-based catalyst The semiconductor device according to claim 1 or 2,
A semiconductor device, wherein the semiconductor element is made of a silicon carbide semiconductor.

Images