JPH01170043A - Manufacture of compound semiconductor device - Google Patents

Abstract

PURPOSE:To enable a selectively deposited layer even in thickness of deposited film to be formed by a method wherein recessions not reaching the crystal surface or projections are formed into dummy patterns on a protective film. CONSTITUTION:The surface of a compound semiconductor 10 is covered with a protective film such as SiO2, Si3N4, WSix, etc., to form a selectively deposited regular pattern 11 and then recessions not reaching the substrate crystal surface or projections are formed into dummy patterns 12 on the peripheral part of the regular pattern 11. In other words, when GaAs is selectively deposited on the regular pattern 11 isolated in wide space, the film thickness is abnormally increased but when the dummy patterns 12 taking the same shape as that of the regular pattern 11 are evenly distributed, the thickness of the deposited film is made even. Furthermore, if the recessed dummy patterns 12 around the regular pattern 11 are formed not to reach the substrate crystal surface, any needless crystal deposited layer is not formed by the dummy patterns 12 to prevent the later manufacturing processes from being restricted.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a compound semiconductor device, and in particular,
The present invention relates to a method suitable for selectively epitaxially growing a semiconductor layer on a semiconductor crystal substrate.

[Conventional technology]

When forming the source and drain regions of a GaAs MESFET by selective growth technology, non-uniformity occurs in the thickness of the grown film due to the size and distribution of the pattern, so in the conventional technology, a dummy pattern is formed around the main pattern to solve this problem. was solved.

[Problem that the invention seeks to solve]

In the above-mentioned prior art, a semiconductor growth layer with a dummy pattern was inevitably formed on the semiconductor crystal substrate in addition to the selective growth layer with the main pattern. For this reason, when a semiconductor integrated circuit or the like is formed on this crystal substrate, there are problems such as more constraints due to the growth layer formed by the dummy pattern.

An object of the present invention is to form a selectively grown layer on a compound semiconductor crystal substrate without producing a grown layer due to a dummy pattern and without non-uniformity in the grown film thickness due to the size and distribution of the pattern. The purpose is to provide a manufacturing method.

[Means for solving problems]

For the above purpose, first, the surface of the compound semiconductor was coated with Sin.

By forming a main pattern to be selectively grown by covering it with a protective film such as S13N41WSIX, and then forming a concave or convex dummy pattern around the main pattern that does not reach the substrate crystal surface. , achieved.

[Effect]

The technique of epitaxially growing GaAs selectively only on the GaAs surface while avoiding the surface of the Si O2v S 1sNne WS ix material is mainly easy to obtain with a growth method called MOCVD. When G a As is selectively grown on the main pattern isolated in the film, the film thickness becomes abnormally thick.

On the other hand, when patterns having the same shape as the present pattern are distributed in a negative pattern, the grown film thickness tends to be uniform.

This is because during crystal growth, crystal atoms or molecules that try to deposit in areas other than the pattern area move around on the protective film, causing GaA
It is interpreted that this is due to concentration in the exposed part of the surface of s. Furthermore, in the case of an isolated pattern, it is known that polycrystalline clusters are formed at positions far away from the pattern. Therefore, in order to suppress variations in the thickness of the grown film depending on the distribution of the shape of the pattern, it is necessary to protect the periphery of the pattern so that the GaAs atoms or molecules deposited in the periphery do not concentrate on the pattern. on the membrane,
This is possible by forming concave portions or convex portions distributed in a −-like manner. In addition, if the concave dummy pattern around the main pattern is prevented from reaching the substrate crystal surface, the dummy pattern can be used to prevent the concave dummy pattern from reaching the substrate crystal surface. Plan view and a-a in Figure 1
This will be explained with reference to FIG. 2, which is a sectional view of the section '.

First, a collector layer is formed on a semi-insulating GaAs substrate 20.
"GaAs layer 21, n-type GaAs layer 22, p"-type GaAs layer 23 serving as a base layer. n-type A that becomes the emitter layer
lGaAs layer 24. Finally, an n+ type Ga A is used as a cap layer to make it easier to make ohmic contact.
s M 25 is sequentially epitaxially grown by the MBE method. Here, for example, the n''' type GaAs layer 21 is doped with Si 5X10'' cm-3, has a thickness of 5000 mm, and has an n type G
The aAs layer 22 is doped with Si to 5 x 101'1 am-" and has a thickness of 3000 nm. The p3 type GaAs layer 23 is doped with Be to 2 x 1019 cm-3 and has a thickness of 1000 nm. The n-type AlGaAs layer 24 has an A1 composition. is 0.3 and Si is 5X
I O”cm-3 doped, 1000mm thick, n-type G
The aAs layer 25 is doped with 5×10 18 cm −3 of Si and has a thickness of 1000 nm.

Next, the entire surface is subjected to a photoresist process and reactive ion etching to a depth of about 800 mm to reach the collector layer 22 in the collector region (main pattern section 11 and its peripheral section 13).
Perform 0-person drilling. Next, the entire surface is covered with a SiO2 film 26.
Approximately 8,000 people are deposited using the CVD method. Next, by a photoresist process and dry/wet etching, the surface of the n0 type GaAs layer 21 is exposed only in the main pattern part 11, and the Si02 film is left in the peripheral part 13 and other parts.

Next, GaA
A concave dummy pattern 12 with a depth of about 5000 people is formed in the SiO2 film 26 so that the surface of the S crystal is not exposed. Here, the planar dimension of the main pattern 11 is, for example, 5 μm.
x 10 μm, and the same was applied to the dummy pattern portion 12, and the distance between the patterns was 5 μm or more and 100 μm or less, and uniformly distributed as shown in FIG.

Next, an n'' GaAs layer 27 is selectively grown by the MOCVD method. Here, for example, the n'' GaAs layer 27 is S
i was 5×101f101f1 doped, the thickness was 8000, and the surfaces of the cap layer 25 and the selective growth layer 27 were made to be equal. At this time, on the dummy pattern 12,
As shown in Fig. 2, cluster 2 of polycrystalline Ga As
8 was deposited.

Next, after etching the SiOH film 26 and removing the polycrystalline GaAs 28 at the same time, the emitter, base, and collector electrodes were formed using a normal process technique to fabricate a heterojunction bipolar transistor structure. Note that the 5iOz film 26 does not necessarily need to be completely removed.

As a result of the above, n° type Ga A s exists only in the collector region.
It is possible to selectively grow layers and achieve a state in which unnecessary growth layers are not formed in other parts.

We were able to fabricate an HBT with a planar structure.

(Example 2) Example 2 in which the present invention is applied to a GaAs-AIGaAs heterojunction bipolar transistor will be explained with reference to the plan view shown in FIG. 3 and FIG. 4 which is a cross-sectional view taken along line bb' in FIG. do.

As in Example 1, a crystal forming a heterojunction bipolar transistor is grown on a semi-insulating GaAs substrate 40 by the MBE method, a hole reaching up to the n'' GaAs layer 41 is formed, and a hole is formed in the peripheral area 33 of the hole. A side wall 46 of an insulating layer made of S i 02 is formed.

At the same time, a protective film 46 made of SiO is formed on the crystal surface.
The e S z 02 formed is approximately 1 μm by CVD method.
Made thick.

Next, a dummy pattern 32 is formed on the protective film around the main pattern 31 using a photoresist process and a dry etching process. The height of the dummy pattern was approximately 6,000 people.

Next, when the n'' GaAs layer 47 is grown by the MOCVD method, crystal growth progresses selectively only in one pattern portion 31. On the other hand, no crystal grows on the protective film 46, and the GaAs
Clusters 48 of s, Ga, or As molecules are deposited, but the dummy pattern 32 suppresses their movement to the main pattern portion.

Therefore, it was possible to obtain a uniform thickness of the regrown n'''GaAs layer 47 without depending on the pattern shape distribution.

Thereafter, as described in Example 1, a planar structure heterojunction bipolar transistor was manufactured using a normal process technique.

〔Effect of the invention〕

According to the present invention, when selectively growing on a compound semiconductor crystal substrate, it is possible to suppress non-uniformity in the grown film thickness due to pattern dimensions and distribution. It becomes possible to selectively grow crystals with a uniform thickness in a pattern.

It goes without saying that the present invention is also effective when selectively regrowing the emitter in a collector top type heterojunction bipolar transistor in which the positions of the emitter and collector are reversed.

[Brief explanation of the drawing]

1 is a plan view of Embodiment 1 of the present invention, and FIG. 2 is a plan view of Embodiment 1 of the present invention.
Embodiment 2 of the present invention, FIG. 3 is a sectional view taken along the line a-a'
FIG. 4 is a sectional view taken along line bb' in FIG. 3. 10.3O-GaAs crystal wafer, 11.31...
Main pattern (collector region), 12.32... Dummy pattern, 13.33... Insulating region by S i 02, 20.40-... Semi-insulating G a A a substrate, 2
1゜41-n"GaAs layer (collector), 22,42"
・N-type GaAs layer (collector), 23.43...
・p''' type GaAs layer (base), 24.44-=n
Type AlGaAs layer (emitter), 25.45-n” type G
a As layer (cap), 26.46-8i02 layer, 27.47...selectively grown n'-type GaAs layer, 28.
...GaAs cluster deposited on dummy pattern, 4
8...GaAs cluster deposited on the protective film. -Shino 27 Goichino J Turn 21 Gummy/J Turn”
=-4 纺4し达ノa 42nd JOGaJls7Emu -l Haθ, Jme'! J
3rd circle 4th rfJ

Claims (1)

[Claims] 1. Using a semiconductor substrate crystal whose surface is covered with a protective film made of SiO_2, Si_3N_4, WSix, etc.,
In a method for manufacturing a compound semiconductor device, which includes a step of forming a dummy pattern around the main pattern and selectively epitaxially growing a compound semiconductor crystal only in the main pattern portion, the dummy pattern is a recessed portion of the protective film that does not reach the crystal surface. Alternatively, a method for manufacturing a compound semiconductor device characterized in that a convex portion is formed. 2. The method for manufacturing a compound semiconductor device according to claim 1, wherein the compound semiconductor crystal is GaAs, and the epitaxial growth method is MOCVD. 3. The method for manufacturing a compound semiconductor device according to claim 1, wherein the shortest distance between the main pattern and the dummy pattern is 100 μm or less.