JP3532972B2 - Method for manufacturing compound semiconductor device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a compound semiconductor device, and more specifically, it removes resist residues and surface stains, which are problems during processing such as etching and electrode formation, and is a clean compound. The present invention relates to a method for obtaining a semiconductor substrate surface.

[0002]

2. Description of the Related Art A compound semiconductor device is required to have a fine recess shape in order to operate at a high frequency and also to have a low contact resistance of electrodes. On the other hand, in manufacturing a compound semiconductor device, it is desirable not to use a dry process in order to avoid deterioration of electrical characteristics. However, if only the organic cleaning is used without using the dry process after removing the resist, the resist residues and stains, which are resist-altered, are easily attached to the surface of the compound semiconductor substrate. When a compound semiconductor substrate surface having resist residues or stains on such a surface is subjected to extremely fine recess processing by wet etching, there arises a problem that variations in etching depth and side etching become large. In addition, when the electrodes are formed, problems such as an increase in contact resistance and peeling of the electrodes may occur due to resist residues and stains.

On the other hand, dry processes such as plasma ashing and plasma etching have been used in the manufacture of silicon semiconductor devices. A method for removing the resist residue at this time is proposed in Japanese Patent Laid-Open No. 4-82221. This method removes the resist residue generated when the aluminum alloy wiring pattern is formed by the etching process using the chlorine-based gas plasma reaction by the fluorine-based gas plasma reaction at the same time as the previously formed underlying sacrificial film. That is.

[0004]

However, when this technique is applied to recess processing and electrode formation in the production of the compound semiconductor device as described above, the surface of the compound semiconductor substrate exposed to the plasma reaction is used as it is, The produced compound semiconductor device has a problem that electrical characteristics such as Schottky characteristics are low.

Therefore, an object of the present invention is to provide a method for manufacturing a compound semiconductor device which can obtain a clean compound semiconductor substrate surface without using a dry process for removing resist residues and surface stains.

[0006]

SUMMARY OF THE INVENTION The first aspect of the present invention, by performing oxidation treatment on the surface of the compound semiconductor substrate comprising at least a gallium or arsenic, at least oxidized gallium
A first step of forming a surface oxide film comprising a beam or arsenic oxide, and a second step of depositing a Les Soo bets on the surface oxide film, exposing the resist using a predetermined mask, developing to
As a result, the desired register in which the surface oxide film is exposed is obtained.
A third step of forming a strike pattern, and an exposed portion of the surface oxide film that is not covered with the resist pattern is exposed to acid.
A fourth step of removing the resist residue and surface stains at the same time by removing it by wet etching with an etching solution containing a, and etching and electrode formation on the clean compound semiconductor substrate surface. The gist is a method for manufacturing a compound semiconductor device including a fifth step to be performed.

According to a second aspect of the present invention, in the method of manufacturing a compound semiconductor device according to the first aspect, the oxidation treatment is performed.
A hydrogen peroxide solution of a predetermined concentration heated and maintained at a predetermined temperature
By immersing the compound semiconductor substrate in the
The gist of the method is a compound semiconductor device manufacturing method.

The invention described in claim 3 is the same as claim 1 or
The method of manufacturing a compound semiconductor device according to 2, 4
The gist is a method of manufacturing a compound semiconductor device in which the etching solution containing the acid used in the step is hydrofluoric acid. The invention according to claim 4 is any one of claims 1 to 3.
In the method of manufacturing a compound semiconductor device according to item 1,
Different resist patterns as resist patterns in 3 steps
A compound that repeats the second to fifth steps using
The manufacturing method of a semiconductor device is the gist.

[0009]

According to the invention described in [action] claim 1, oxidation treatment on the surface of the compound semiconductor substrate comprising at least a gallium or arsenic is performed by the first step, at least oxidized gallium
Surface oxide film comprising a beam or arsenic oxide is formed and Soo bets are deposited on the surface oxide film by the second step. Then, in the third step, the resist is exposed using a predetermined mask.
The surface oxide film was exposed by light and development
A desired resist pattern is formed. After that, the 4th work
The exposed portion of the surface oxide film which is not covered with the resist pattern is removed by wet etching with an etching solution containing an acid, whereby resist residues and surface stains are removed at the same time, which is a clean compound semiconductor substrate. The surface is exposed. In other words, gallium oxide, or even without any small
Surface oxide film is damaged friendliness is dissolved in an etchant containing an acid containing arsenic oxide, in the fourth step, the dirt of the resist residues and the surface together with the dissolution of the oxide film of the compound semiconductor substrate by wet et <br/> etching removal Thus, a clean compound semiconductor substrate surface is obtained.

Further, in the fifth step, etching and electrode formation are performed on the surface of the clean compound semiconductor substrate. According to the invention of claim 2 , in the first step, the compound is
The object semiconductor substrate has a predetermined concentration that is heated and maintained at a predetermined temperature.
Oxidation treatment by immersing in hydrogen peroxide
Be treated.

According to the third aspect of the invention , the surface oxide film is wet-etched with hydrofluoric acid in the fourth step. According to the invention of claim 4, the third step
Different resist pattern as the resist pattern in
The second to fifth steps are repeatedly performed by using the above. Tsuma
After forming the surface oxide film, use different resist patterns.
Removing the surface oxide film, etching and electrode
The steps of forming are sequentially repeated. As a result, the previous
Resist residue and surface generated in resist pattern formation process
Clean compound when needed without being affected by dirt
The surface of the object semiconductor substrate is exposed.

[0012]

【Example】

(First Embodiment) A first embodiment of the present invention will be described below with reference to the drawings.

In this embodiment, a gallium arsenide compound semiconductor substrate is recess-etched, and the manufacturing process is shown in FIGS. Further, FIG. 6 shows the results of summarizing the peak areas of oxygen and carbon on the surface of the compound semiconductor substrate using XPS in each step.

First, as shown in FIG. 1, a gallium arsenide compound semiconductor substrate 1 to be subjected to recess etching is prepared. Then, as shown in FIG. 2, the surface of the gallium arsenide compound semiconductor substrate 1 is oxidized to form a surface oxide film 2 containing gallium oxide and arsenic oxide. This surface oxide film treatment is carried out by treating the gallium arsenide compound semiconductor substrate 1 with 5% in 200 ml of 18% hydrogen peroxide solution at 80 ° C.
Soak for a minute. When the surface oxide film 2 formed at this time was analyzed by Auger electron spectroscopy, the thickness of the surface oxide film 2 was about 35Å.

Next, as shown in FIG. 3, a positive resist is applied on the surface oxide film 2 to a thickness of 1.4 μm, and a bribake is carried out at 100 ° C. for 120 seconds. The film is exposed using a mask and then developed. Then, a desired resist pattern 3 is formed.
At this time, in the developed portion, that is, in the exposed portion of the surface oxide film 2 which is not covered with the resist pattern 3 (opening 4 of the resist pattern 3), a resist residue which is a development residue and a surface stain 5 are generated. It

The change in the surface of the gallium arsenide compound semiconductor substrate described above is apparent from the surface analysis by XPS shown in FIG. That is, as shown in FIG. 2 from the state of FIG. 1, the oxygen peak area was greatly increased from the initial stage of the substrate by performing the oxidation treatment, and it was shown that an oxide film was formed on the surface of the gallium arsenide compound semiconductor substrate. ing.
Further, as shown in FIG. 3, the peak area of carbon increases after the step of forming the resist pattern 3, which indicates that resist residues and surface stains 5 have occurred.

Subsequently, the gallium arsenide compound semiconductor substrate 1 having the resist pattern 3 formed thereon is immersed in 5% hydrofluoric acid for 5 minutes. As a result, as shown in FIG. 4, the surface oxide film 2 in the opening 4 (exposed portion of the surface oxide film 2) of the resist pattern 3 is removed. XPS after this process
As shown in FIG. 6, the analysis result shows that both the oxygen peak area and the carbon peak area decrease, and the surface oxide film 2 is dissolved while the compound semiconductor substrate 1 is immersed in hydrofluoric acid. This indicates that the resist residue and the surface stain 5 are also removed.

In this way, a clean compound semiconductor substrate surface is obtained. As shown in FIG. 5, recess etching is performed on the clean surface of the compound semiconductor substrate to obtain a desired etching shape. In this way, the etching shape can be stably produced using a clean compound semiconductor substrate surface.

As described above, in this embodiment, the surface of the gallium arsenide compound semiconductor substrate 1 is oxidized to form the surface oxide film 2 (first step), and a resist is formed on the surface oxide film 2.
Deposit (second step) and use this resist with a specified mask
The surface oxide film is exposed by exposing and developing
The desired resist pattern 3 thus formed is formed ( third step), and the exposed portion of the surface oxide film 2 which is not covered with the resist pattern 3 is removed by wet etching to simultaneously remove the resist residue and the surface stain 5. ,
Exposing a clean compound semiconductor substrate surface ( 4th step),
The clean compound semiconductor substrate surface was etched ( fifth step).

As described above, a clean compound semiconductor substrate surface can be obtained without using a dry process in the etching step, variations in etching depth and side etching can be reduced, and a stable compound semiconductor device can be manufactured.

Since the surface oxide film 2 is wet-etched with hydrofluoric acid, the surface oxide film 2 can be surely wet-etched. In the above embodiment,
Although the case of using a gallium arsenide compound semiconductor substrate has been described, it can be applied to a binary, ternary, or quaternary compound semiconductor substrate containing at least gallium or arsenic such as indium gallium arsenide, indium aluminum arsenide, and aluminum gallium arsenide. Is. However, the compound semiconductor substrate mentioned here is not limited to a single substrate as shown in FIG. 1, but a plurality of films having different compositions including gallium or arsenic, which have been subjected to processing such as electrode formation or etching on the surface. Also includes those in which are laminated. Further, in the above example, the oxidation treatment of the surface of the compound semiconductor substrate was carried out by immersing it in heated hydrogen peroxide solution, but in addition, it may be immersed in hydrogen peroxide solution at room temperature or in water heated at room temperature. Immersion, and since the surface oxide film is removed later, plasma oxidation method or thermal oxidation method,
Various methods are conceivable, such as utilizing the anodizing method.

Further, in the above embodiment, the case where the clean compound semiconductor substrate surface is etched as the fourth step has been described, but it may be applied when the electrode is formed on the clean compound semiconductor substrate surface. At this time, a clean compound semiconductor substrate surface can be obtained without using a dry process in the electrode formation step, contact failure of the electrodes can be reduced, and a stable compound semiconductor device can be manufactured. (Second Embodiment) Next, the second embodiment will be described focusing on the differences from the first embodiment.

In this embodiment, a case of including a step of forming an ohmic electrode and a step of performing recess etching (and forming a Schottky electrode) on the surface of a gallium arsenide compound semiconductor substrate will be described with reference to FIGS. 7 to 14. .

First, as shown in FIG. 7, the surface oxide film 2 containing gallium oxide and arsenic oxide is formed on the surface of the gallium arsenide compound semiconductor substrate 1 under the same surface oxidation treatment conditions as in the first embodiment.

Next, as shown in FIG. 8, a resist pattern 3 for an ohmic electrode is formed as in the first embodiment. At this time, in the opening 4 of the resist pattern 3,
Resist residues that are undeveloped and surface stains 5a are generated. Then, as shown in FIG. 9, the compound semiconductor substrate 1
Is immersed in hydrofluoric acid to remove the surface oxide film 2 in the opening 4 of the resist pattern 3. At this time, the resist residue that is the undeveloped residue and the surface stain 5a are also removed at the same time, and the clean gallium arsenide compound semiconductor substrate surface is exposed. Then, as shown in FIG. 10, gold-germanium / nickel /
After vapor deposition of gold and lift-off, alloying treatment is performed to form the ohmic electrode 6.

Further, as shown in FIG. 11, a resist pattern 7 for recess etching is formed similarly to the first embodiment. At this time, the opening 8 of the resist pattern 7
On the other hand, a resist residue which is a development residue and a surface stain 5b are generated. Then, as shown in FIG. 12, the compound semiconductor substrate 1 is immersed in hydrofluoric acid to form a resist pattern 7.
The surface oxide film 2 in the opening 8 is removed. At this time, the resist residue that is the undeveloped residue and the surface contamination 5b are also removed at the same time, and the clean gallium arsenide compound semiconductor substrate surface is exposed.

Subsequently, as shown in FIG. 13, the surface of the compound semiconductor substrate 1 is subjected to etching treatment to obtain a recess shape, and then titanium / platinum / gold is vapor-deposited as shown in FIG. The electrode 9 is formed.

As described above, in this embodiment, the second to fifth steps are repeated by using different resist patterns 3 and 7 as resist patterns. That is, the step of forming the surface oxide film 2 and forming a different resist pattern prior to all the steps, the step of removing the surface oxide film 2, and the step of etching or forming electrodes were sequentially repeated. Therefore, it is possible to always obtain a clean compound semiconductor substrate surface without being affected by the resist residue and surface stains generated in the previous resist pattern forming step. In this way, by simply forming the surface oxide film 2 first, a clean compound semiconductor substrate surface can be obtained by performing acid treatment at a necessary position when necessary.

The present invention is not limited to the above-mentioned embodiments. For example, instead of hydrofluoric acid as an etching solution for removing the surface oxide film 2, dilute sulfuric acid, acetic acid, citric acid, or ammonia is used. May be used.

[0030]

As described in detail above, according to the invention described in claim 1, it is possible to obtain a clean compound semiconductor substrate surface without using a dry process for removing resist residues and surface stains. Be effective.

According to the invention described in claim 2 , the compound semi
A desired surface oxide film can be reliably formed on the conductor substrate .

According to the invention described in claim 3, it is possible to reliably wet etched front surface oxide film. Claim
According to the invention of item 4, any one of claims 1 to 3
In addition to the effects of the invention described in the item 1,
It is affected by resist residue and surface stains generated during the formation process.
Clean compound semiconductor substrate surface without need
Can be exposed.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a manufacturing process of a compound semiconductor device of a first embodiment.

FIG. 2 is a cross-sectional view showing a manufacturing process of the compound semiconductor device of the first embodiment.

FIG. 3 is a cross-sectional view showing a manufacturing process of the compound semiconductor device of the first example.

FIG. 4 is a cross-sectional view showing a manufacturing process of the compound semiconductor device of the first example.

FIG. 5 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the first example.

FIG. 6 is a diagram showing a result obtained by performing surface analysis by XPS for each step in the first example and summarizing peak areas of oxygen and carbon.

FIG. 7 is a cross-sectional view showing a manufacturing process of the compound semiconductor device of the second embodiment.

FIG. 8 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the second embodiment.

FIG. 9 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the second example.

FIG. 10 is a cross-sectional view showing a manufacturing process of the compound semiconductor device of the second embodiment.

FIG. 11 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the second example.

FIG. 12 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the second example.

FIG. 13 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the second embodiment.

FIG. 14 is a cross-sectional view showing the manufacturing process of the compound semiconductor device of the second example.

[Explanation of symbols]

1 ... Gallium arsenide compound semiconductor substrate, 2 ... Surface oxide film,
3 ... Resist pattern, 4 ... Aperture, 5 ... Resist residue and surface stain, 6 ... Ohmic electrode, 7 ... Resist pattern, 8 ... Aperture, 9 ... Schottky electrode

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor, Michiyo Mizutani, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nippon Denso Co., Ltd. (72) Inventor, Tetsuo Toyama, 1-1, Showa-cho, Kariya city, Aichi prefecture, Nippon Denso Co., Ltd. (56) References JP-A-3-18037 (JP, A) JP-A-6-37117 (JP, A) JP-A-6-200384 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/304 H01L 21/027 H01L 21/308

Claims (4)

(57) [Claims] 1. A surface of a compound semiconductor substrate containing at least gallium or arsenic is subjected to an oxidation treatment, and at least
A first step of forming a surface oxide film containing gallium oxide or arsenic oxide, and a second step of depositing a Les Soo bets on the surface oxide film, exposing the resist using a predetermined mask, developing child
The desired layer in which a part of the surface oxide film is exposed by
The third step of forming a dist pattern and the exposed portion of the surface oxide film which is not covered with the resist pattern are removed by wet etching using an etching solution containing an acid to simultaneously remove the resist residue and surface stains and clean the surface. 4. A method for manufacturing a compound semiconductor device, comprising: a fourth step of exposing the surface of the compound semiconductor substrate; and a fifth step of etching or forming electrodes on the surface of the clean compound semiconductor substrate. 2. The method of manufacturing a compound semiconductor device according to claim 1, wherein the oxidation treatment is performed by heating at a predetermined temperature.
The compound semiconductor substrate is immersed in hydrogen peroxide solution having a predetermined concentration.
A method for manufacturing a compound semiconductor device, which is performed by dipping for a predetermined time . 3. A method of manufacturing a compound semiconductor device according to claim 1 or 2, wherein the acid used in the fourth step
The method for manufacturing a compound semiconductor device, wherein the etching liquid containing is hydrofluoric acid. 4. The compound according to any one of claims 1 to 3.
In the manufacturing method of the compound semiconductor device, the registration in the third step is performed.
Use different resist patterns as strike patterns.
Of a compound semiconductor device in which steps 2 to 5 are repeated
Production method.