JPH02164028A - Formation of electrode of silicon carbide semiconductor element - Google Patents
Formation of electrode of silicon carbide semiconductor elementInfo
- Publication number
- JPH02164028A JPH02164028A JP32092388A JP32092388A JPH02164028A JP H02164028 A JPH02164028 A JP H02164028A JP 32092388 A JP32092388 A JP 32092388A JP 32092388 A JP32092388 A JP 32092388A JP H02164028 A JPH02164028 A JP H02164028A
- Authority
- JP
- Japan
- Prior art keywords
- electrode film
- electrode
- film
- type sic
- silicon carbide
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 title claims description 36
- 229910010271 silicon carbide Inorganic materials 0.000 title claims description 35
- 239000004065 semiconductor Substances 0.000 title claims description 8
- 230000015572 biosynthetic process Effects 0.000 title description 2
- 238000000151 deposition Methods 0.000 claims abstract description 7
- 238000000034 method Methods 0.000 claims description 20
- 239000000758 substrate Substances 0.000 abstract description 13
- 238000010438 heat treatment Methods 0.000 abstract description 9
- 238000001771 vacuum deposition Methods 0.000 abstract description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-N Fluorane Chemical compound F KRHYYFGTRYWZRS-UHFFFAOYSA-N 0.000 description 9
- 238000009792 diffusion process Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 3
- QPJSUIGXIBEQAC-UHFFFAOYSA-N n-(2,4-dichloro-5-propan-2-yloxyphenyl)acetamide Chemical compound CC(C)OC1=CC(NC(C)=O)=C(Cl)C=C1Cl QPJSUIGXIBEQAC-UHFFFAOYSA-N 0.000 description 3
- 238000004381 surface treatment Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000001039 wet etching Methods 0.000 description 2
- 229910018540 Si C Inorganic materials 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
Landscapes
- Electrodes Of Semiconductors (AREA)
Abstract
Description
【発明の詳細な説明】
（イ）産業上の利用分野
本発明は炭化ケイ素半導体素子の電極形成方法に関する
。DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a method for forming electrodes of silicon carbide semiconductor devices.
（ロ） 従来の技術
炭化ケイ素（ＳｉＣ）は高温高圧下で動作可能な半導体
材料として注目されており、また光学的バンドギャップ
が広く容易にｐｎ接合が形成できることから青色発光素
子材料としても期待されている。(b) Conventional technology Silicon carbide (SiC) is attracting attention as a semiconductor material that can operate under high temperature and high pressure, and is also expected to be used as a material for blue light-emitting devices because it has a wide optical bandgap and can easily form p-n junctions. ing.
斯るＳｉＣ半導体素子には、従来オーミック電極として
、１９８７年秋期応用物理学会予稿集、２９ａ−Ｗ−１
，５８６頁に示されている如く、ｐ型ＳｉＣ上にＡ６／
Ｓｉ、ｎをＳｉＣ上にＮｉが用いられている。Such SiC semiconductor devices are conventionally used as ohmic electrodes, Proceedings of the Japan Society of Applied Physics, Autumn 1987, 29a-W-1.
, page 586, A6/A6/
Ni is used on Si, n and SiC.
第２図に従来のＳｉ半導体素子、例えばＳｉＣ八
発光ダイオードの構造を示す。斯るＳｉＣ発光ダイオー
ドの製造方法は１例えばｎ型ＳｉＣ基板（８）の−主面
上に、ｎ型ＳｉＣ層（９）、ｐ型ＳｉＣ層＋ＩＱ）をＬ
ＰＥ法を用いて順次成長する。次いで上記ｎ型ＳｉＣ基
板（８）の他主面上にＮｉ電極ＩＢＩ （１１）を真空
蒸着し、これを１０００℃で約５分間熱処理する。これ
により、ｎ型ＳｉＣ基板（８）とＮｉ電極ＩＢＩ（１１
）は合金化し、オーミック性を得る。次に、斯るｎ型Ｓ
ｉＣ基板（８）をフッ酸〈ＨＦ）によるウェットエツチ
ングで表面処理した後、ｎ型ＳｉＣ層（１０）上にＡ＋
２．／Ｓｉ電極膜（１２）を真空蒸着し、これを９００
〜９５０℃で約５分間熱処理する。これによりｎ型Ｓｉ
Ｃ層（１０）とＡＱ ／ Ｓ ｉ電極１１５Ｉ（１２＋
は合金化し、オーミック性を得る。最後にワイヤボンド
用電極として周知であるＡｕ／Ｃｒ電極膜（１３）をＮ
ｉ電極膜（１１）上に積層してＳｉＣ発光ダイオードを
得る。FIG. 2 shows the structure of a conventional Si semiconductor device, such as a SiC eight light emitting diode. The manufacturing method of such a SiC light emitting diode is as follows: 1. For example, on the - main surface of an n-type SiC substrate (8), an n-type SiC layer (9), a p-type SiC layer + IQ) is formed
Sequential growth is performed using the PE method. Next, a Ni electrode IBI (11) is vacuum-deposited on the other main surface of the n-type SiC substrate (8) and heat-treated at 1000° C. for about 5 minutes. As a result, the n-type SiC substrate (8) and the Ni electrode IBI (11
) becomes alloyed and acquires ohmic properties. Next, such n-type S
After surface-treating the iC substrate (8) by wet etching with hydrofluoric acid (HF), A+
2. /Si electrode film (12) was vacuum deposited and
Heat treatment at ~950°C for about 5 minutes. As a result, n-type Si
C layer (10) and AQ/Si electrode 115I (12+
is alloyed and acquires ohmic properties. Finally, the Au/Cr electrode film (13), which is well known as a wire bond electrode, is
It is laminated on the i-electrode film (11) to obtain a SiC light emitting diode.
しかし乍ら、斯る従来の発光ダイオードではその製造工
程中のＨＦによる表面処理の際にＮｉ電極Ｈ（１１）が
若干酸化し、このためワイヤボンド用電極として形成し
たＡ ｕ ／ Ｃを−電極膜（１３）との密着性が低下
し、Ｎｉ電極膜（１１）とＡ ｕ ／ Ｃｒ電極膜（５
１（１３］との界面でＭｍが発生することが多い。この
問題を解決するなめ、例えば「電子技術」日刊工業新聞
発行、第２６巻１４号（１９８４）１２８〜１３０頁に
示されている様に酸化されにくいＡｕ／Ｎｉ電ｆ！膜が
Ｎｉ電極膜（１１）に変わって用いられる。しかし、こ
の方法においてもＡ ｕ ／ Ｎｉ電極膜形成後に施さ
れる１０００°Ｃの熱処理の際に、ＡｕとＮｉが反応し
て一部のＡｕが電極下層に移動するため、電極表面では
Ａｕが島状に残り、池の場所でＮｉが現れる。そして表
面に現われたＮｉ上で自然酸化膜が形成されるため、結
局、斯る電極とワイヤボンド線又はワイヤボンド用電極
であるＡ ｕ ／ Ｃｒ電４ｆ！膜との結合力が弱くな
ってしまう。However, in such conventional light emitting diodes, the Ni electrode H (11) is slightly oxidized during the surface treatment with HF during the manufacturing process, and for this reason, the A u / C formed as the wire bonding electrode is used as the - electrode. The adhesion with the film (13) decreases, and the Ni electrode film (11) and the Au/Cr electrode film (5
Mm often occurs at the interface with 1(13).Methods for solving this problem are shown, for example, in "Electronic Technology", published by Nikkan Kogyo Shimbun, Vol. 26, No. 14 (1984), pp. 128-130. An Au/Ni electrode film (11), which is difficult to oxidize, is used in place of the Ni electrode film (11). However, even in this method, during the 1000°C heat treatment performed after forming the Au/Ni electrode film, , Au and Ni react and some Au moves to the lower layer of the electrode, so Au remains in the form of islands on the electrode surface, and Ni appears at the pond.A natural oxide film forms on the Ni that appears on the surface. As a result, the bonding force between such an electrode and the A u /Cr film, which is a wire bond line or a wire bond electrode, becomes weak.
（ハ） 発明が解決しようとする課題
したがって本発明は、強固にワイヤボンド可能なｎ型Ｓ
ｉＣの電極形成方法を提供するものである。(c) Problems to be Solved by the Invention Therefore, the present invention provides an n-type S that can be firmly wire bonded.
A method for forming an iC electrode is provided.
（ニ）課題を解決するための手段
本発明は、炭化ケイ素半導体素子に電極を形成する方法
において、上記課題を解決するため、ｎ型炭化ケイ素上
にＮｉ電極膜を被着する工程、該Ｎｉ電極膜上にＰｄ電
極膜を被着する工程、上記Ｎｉ電電膜膜び上記ｐｄ電極
膜を熱処理する工程、を備えることを特徴とする。(d) Means for Solving the Problems In order to solve the above problems, the present invention provides a method for forming electrodes on silicon carbide semiconductor devices, including a step of depositing a Ni electrode film on n-type silicon carbide, and a step of depositing a Ni electrode film on n-type silicon carbide. The method is characterized by comprising a step of depositing a Pd electrode film on the electrode film, and a step of heat-treating the Ni electrolytic film and the Pd electrode film.
（ホ）作用
本発明方法は、ｎ型ＳｉＣとオーミック接触可能なＮｉ
′ｒｆ、ｆ！膜の上にＰｄ電極膜を被着する。このＰｄ
電極膜は１２００°Ｃ以下ではＮｉ電極膜と反応しない
、またＰｄ電極膜は酸化しにくい性質を有する。(E) Effect The method of the present invention is based on Ni which can make ohmic contact with n-type SiC.
'rf, f! A Pd electrode film is deposited on top of the film. This Pd
The electrode film does not react with the Ni electrode film at temperatures below 1200°C, and the Pd electrode film has a property of not being easily oxidized.
（へ）実施例
第１図は本発明方法の一実施例を示す工程別断面図であ
る。以下図を参照して本発明方法を詳述する。(f) Example FIG. 1 is a sectional view of each step showing an example of the method of the present invention. The method of the present invention will be explained in detail below with reference to the figures.
第１図（ａ）は第１の工程を示し、先ずｎ型ＳｉＣ基板
（１）を準備する。そして、その−主面上に、ＬＰＥ法
、ＣＶＤ法等の周知のエピタキシャル法を用いてｎ型Ｓ
ｉＣ層（２）、ｎ型ＳｉＣ層（３）を順次積層する。FIG. 1(a) shows the first step, in which an n-type SiC substrate (1) is first prepared. Then, on the main surface, an n-type S
An iC layer (2) and an n-type SiC layer (3) are sequentially laminated.
第１図（ｂ）は第２の工程を示し、ｎ型ＳｉＣ基板（１
）の他主面上に、真空蒸着法を用いて、Ｎｉ電）ＮＪＮ
（４）ヲ５０ ＯＡ、ＰｄｔａｉＪｌｉ（５）を３０
００人、夫々蒸着する。しかる後、斯る積層基板を１０
００℃で約５分間熱処理する。これによりＮｉ電極膜（
４）はｎ型ＳｉＣ基板（１）と合金化しオーミック性を
得る。また、この１０００℃の熱処理においてＰｄ電極
膜（５）はＮｉ電極膜（４）と反応しない。したがって
、Ｎｉ電極１１！＋４１中のＮｉはＰｄ電極膜（５）内
を通ってＰｄ電′ＪＦ！ｉ１膜（５）表面に現われない
。FIG. 1(b) shows the second step, in which the n-type SiC substrate (1
) on the other main surface using a vacuum evaporation method.
(4) 50 OA, PdtaiJli (5) 30
00 people each deposited. After that, 10 such laminated substrates were
Heat treatment at 00°C for about 5 minutes. This allows the Ni electrode film (
4) is alloyed with the n-type SiC substrate (1) to obtain ohmic properties. Further, in this heat treatment at 1000° C., the Pd electrode film (5) does not react with the Ni electrode film (4). Therefore, Ni electrode 11! The Ni in +41 passes through the Pd electrode film (5) and becomes a Pd electrode 'JF! It does not appear on the i1 film (5) surface.
第１図（ｃ）は第３の工程を示し、ｎ型ＳｉＣ層（３）
上に、フッ酸（ＨＦ）によるウェットエツチングにて表
面処理を施した後、真空蒸着法を用いて、５ｉＪ１１を
１００ｏ人、Ａρ膜を７０００人、夫々蒸着しＡｇ／Ｓ
ｉ電極膜（６）を形成する。しかる後、斯る積層基板を
９００〜１０００℃、例えば９５０℃で約５分間熱処理
する。これによりＡＲ／Ｓｉ電極Ｍ（６）はＰ型ＳｉＣ
層（３）と合金化し、オーミック性を得る。斯る工程の
中の、フッ酸によるｐ型５ｉＣＪｉｌ（３）の表面処理
の際に、Ｐｄ電極膜（５）表面に酸化膜は形成されない
。これは、Ｐｄ電ｔｆｓＭ（５＞が酸化されにくい性質
を有すること及びＰｄ電極膜（５）表面に下層中のＮｉ
が現われないことによる。FIG. 1(c) shows the third step, in which the n-type SiC layer (3)
After surface treatment by wet etching with hydrofluoric acid (HF), 100 layers of 5iJ11 and 7000 layers of Aρ film were deposited using vacuum evaporation method to form Ag/S.
An i-electrode film (6) is formed. Thereafter, the laminated substrate is heat-treated at 900 to 1000°C, for example, 950°C, for about 5 minutes. As a result, the AR/Si electrode M(6) is made of P-type SiC
Alloyed with layer (3) to obtain ohmic properties. During the surface treatment of the p-type 5iCJil (3) with hydrofluoric acid in this process, no oxide film is formed on the surface of the Pd electrode film (5). This is because the Pd electrode film (5) has a property of being difficult to oxidize and the surface of the Pd electrode film (5) has Ni in the lower layer.
This is due to the fact that it does not appear.
第１図（ｄ）は第４の工程を示し、Ｐｄ電極膜（５）上
に、真空蒸着法を用いて、例えばＴ ｉ １１％を１０
００人、Ｐｄ膜を２０００人、Ａｕ膜を３０００人蒸着
し、ワイヤボンド用電極として周知のＡ ｕ ／ Ｐ
ｄ ／ Ｔ ｉ電極ｆｉ（７）を形成する。斯るＡ ｕ
／ Ｐ ｄ ／ Ｔ ｉ電極膜（７）はＰｄ電極［（
５）表面に酸化膜が存在しないため、Ｐｄ電４ｉ１１（
５１と強固に結合する。FIG. 1(d) shows the fourth step, in which, for example, 10% of Ti 11% is deposited on the Pd electrode film (5) using a vacuum evaporation method.
00 people, 2000 people deposited Pd film, 3000 people deposited Au film, and A u / P which is well known as a wire bond electrode.
Form a d/Ti electrode fi (7). Such A u
/ P d / Ti electrode film (7) is a Pd electrode [(
5) Since there is no oxide film on the surface, Pd electron 4i11(
51 and is strongly connected.
本実施例においてＮｉ電ｆ！１１５！ （４）、Ｐｄ電
４ｉｌｉ！膜（５）はｎ型ＳｉＣ基板（１）上に形成し
たが、ｎ型ＳｉＣエピタキシャル層の上に形成しても同
様の効果が得られる。In this example, Ni electric f! 115! (4), Pdden4ili! Although the film (5) was formed on the n-type SiC substrate (1), the same effect can be obtained even if it is formed on the n-type SiC epitaxial layer.
また、本発明方法におけるＰｄ電極膜は高融点を有する
ため、熱処理の際に変形しない、これに伴い下層のＮｉ
電極膜も変形を生じにくくなる。In addition, since the Pd electrode film in the method of the present invention has a high melting point, it does not deform during heat treatment, and as a result, the underlying Ni
The electrode film also becomes less likely to be deformed.
このため本発明方法においては、Ｎ１ｔｆ！膜の膜厚を
厚くして電極膜の変形による素子内の電界不均一を抑え
る必要はなく、Ｎｉ電極膜の膜厚を自由に設定できる。Therefore, in the method of the present invention, N1tf! There is no need to increase the thickness of the film to suppress non-uniformity of the electric field within the device due to deformation of the electrode film, and the thickness of the Ni electrode film can be set freely.
また、Ｎ１電極膜の厚さが、熱処理の際に、Ｎｉ電ｆ！
膜中のＮｉのＳｉＣへの拡散深さに関係すること、及び
熱処理の際にＮｉ電極膜とＰｄ電極膜が反応しないなめ
、Ｎｉ電極膜中のＮｉの拡散がＳｉＣへのみ起こること
から本発明方法においては、Ｎｉ電極膜の膜厚を適宜変
化させることによって、Ｎｉの拡散深さを容易に制御で
きる。斯るＮｉの拡散した部分のＳｔＣは導通状態とな
るので、Ｎｉ電ｆ！膜が被着されるＳｉＣの厚さは拡散
深さより厚くしなければならない０本発明方法では上述
の如（Ｎｉ電極膜の膜厚を薄くすることによって、拡散
深さを極力浅くすることができるので、Ｎｉ電極膜が被
着されるＳｉＣの厚さを薄くすることができる。これに
より、素子の比抵抗が下がるため、動作時の発熱量を抑
えることができ、素子劣化が起こりにくくなるため、素
子の信顆性が向上する。さらに、本発明方法を、ｐｎｐ
型ＳｉＣバイポーラトランジスタにおけるベース用電極
の形成に適用すれば、ベース層となるｎ型ＳｉＣ層の層
厚を、上記理由により極力薄くすることができるので、
応答特性の良いバイポーラトランジスタが得られる。In addition, the thickness of the N1 electrode film changes during heat treatment.
The present invention is related to the depth of diffusion of Ni in the film into SiC, and because the Ni electrode film and Pd electrode film do not react during heat treatment, the diffusion of Ni in the Ni electrode film occurs only into SiC. In this method, the depth of Ni diffusion can be easily controlled by appropriately changing the thickness of the Ni electrode film. Since the StC in the part where Ni is diffused becomes conductive, the Ni electric f! The thickness of the SiC to which the film is deposited must be thicker than the diffusion depth. In the method of the present invention, as described above (by reducing the thickness of the Ni electrode film, the diffusion depth can be made as shallow as possible). Therefore, the thickness of the SiC on which the Ni electrode film is adhered can be made thinner.This reduces the specific resistance of the element, which reduces the amount of heat generated during operation, making it less likely that the element will deteriorate. , the reliability of the device is improved.Furthermore, the method of the present invention can be applied to pnp
If applied to the formation of a base electrode in a type SiC bipolar transistor, the layer thickness of the n-type SiC layer serving as the base layer can be made as thin as possible for the above reasons.
A bipolar transistor with good response characteristics can be obtained.
（ト）発明の効果
本発明方法によれば、Ｎ１電極膜上にＰｄ電極膜を被着
することによって、熱処理の後、Ｐｄ電極膜表面に酸化
膜が形成されない。このためＰｄ電極膜上に形成するワ
イヤボンド用型ｆＩｗＡは当該Ｐｄ電極膜と強固に結合
することができる。さらに容易にＮｉのＳｉＣへの拡散
深さを制御できるので、ｎ型ＳｉＣ層の厚さを薄くでき
、素子の特性を向上させることができる。(G) Effects of the Invention According to the method of the present invention, by depositing the Pd electrode film on the N1 electrode film, no oxide film is formed on the surface of the Pd electrode film after heat treatment. Therefore, the wire bonding mold fIwA formed on the Pd electrode film can be firmly bonded to the Pd electrode film. Furthermore, since the depth of diffusion of Ni into SiC can be easily controlled, the thickness of the n-type SiC layer can be reduced, and the characteristics of the device can be improved.
第１図は本発明方法の一実施例を示す工程別断面図、第
２図は従来装置を示す断面図である。
第１図FIG. 1 is a sectional view of each step showing an embodiment of the method of the present invention, and FIG. 2 is a sectional view of a conventional apparatus. Figure 1
Claims (1)
いて、ｎ型炭化ケイ素上にＮｉ電極膜を被着する工程、
該Ｎｉ電極膜上にＰｄ電極膜を被着する工程、上記Ｎｉ
電極膜及び上記Ｐｄ電極膜を熱処理する工程、を備える
ことを特徴とする炭化ケイ素半導体素子の電極形成方法
。(1) In a method of forming an electrode on a silicon carbide semiconductor device, a step of depositing a Ni electrode film on n-type silicon carbide;
a step of depositing a Pd electrode film on the Ni electrode film;
A method for forming an electrode for a silicon carbide semiconductor device, comprising the step of heat-treating an electrode film and the Pd electrode film.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32092388A JP2708829B2 (en) | 1988-12-19 | 1988-12-19 | Method of forming electrode of silicon carbide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32092388A JP2708829B2 (en) | 1988-12-19 | 1988-12-19 | Method of forming electrode of silicon carbide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02164028A true JPH02164028A (en) | 1990-06-25 |
| JP2708829B2 JP2708829B2 (en) | 1998-02-04 |
Family
ID=18126789
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32092388A Expired - Fee Related JP2708829B2 (en) | 1988-12-19 | 1988-12-19 | Method of forming electrode of silicon carbide |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2708829B2 (en) |
-
1988
- 1988-12-19 JP JP32092388A patent/JP2708829B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2708829B2 (en) | 1998-02-04 |
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