JPH03201425A - Semiconductor device - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] Regarding the improvement of semiconductor devices, particularly the improvement of semiconductor devices formed on a gallium arsenide layer grown heteroepitaxially on a silicon substrate, the present invention relates to the improvement of semiconductor devices formed on a gallium arsenide layer formed on a silicon substrate. The semiconductor device that is formed, more specifically, the formation of a high-quality gallium arsenide single crystal layer on a silicon substrate, which has significantly reduced defect density due to fewer defects such as dislocations, and has good surface morphology. The purpose is to provide a method to do this, and this purpose can be achieved by any of the following means.

A first means includes a silicon substrate, a gallium arsenide layer provided on the silicon substrate, and a buffer layer containing gallium phosphide provided between the silicon substrate and the gallium arsenide layer. This is a semiconductor device formed on a semiconductor substrate.

A second means is the semiconductor device according to claim 1, wherein the buffer layer is a single layer of gallium phosphide.

A third means is characterized in that the buffer layer is a superlattice structure in which a gallium phosphide layer and a gallium arsenide layer are laminated.
1] is the semiconductor device described.

A fourth means includes a buffer layer made of the superlattice,
4. The semiconductor device according to claim 3, wherein the composition is such that gallium phosphide is abundant on the side of the lower silicon substrate, and the composition is successively rich in gallium arsenide toward the side of the upper gallium arsenide layer.

A fifth means is the semiconductor device according to claim 3, wherein a second buffer layer made of gallium phosphide is provided below the buffer layer made of the superlattice.

A sixth means includes a buffer layer made of the superlattice,
There is a lot of gallium phosphide on the side of the lower gallium phosphide layer.
6. The semiconductor device according to claim 5, wherein gallium arsenide is gradually increased in composition toward the upper gallium arsenide layer.

A seventh means is the semiconductor device according to claim 3, wherein a second buffer layer made of aluminum arsenic is provided between the buffer layer made of the superlattice and the silicon substrate.

An eighth means is the semiconductor device according to claim 3, wherein a second buffer layer made of gallium arsenide is provided between the buffer layer made of the superlattice and the silicon substrate.

A ninth means is the semiconductor device according to claim 8, wherein a third buffer layer made of aluminum arsenide or gallium phosphide is provided between the second buffer layer and the silicon substrate.

[Industrial application field]

The present invention relates to improvements in semiconductor devices. In particular, the present invention relates to improvements in semiconductor devices using gallium arsenide as an active layer. More specifically, the present invention relates to an improvement in a semiconductor device in which a gallium arsenide layer heteroepitaxially grown on a silicon substrate is formed as an active layer.

[Conventional technology]

Conventionally, semiconductor devices using gallium arsenide as an active layer were formed using a gallium arsenide layer homoepitaxially grown on a gallium arsenide substrate, but in order to reduce the manufacturing cost of semiconductor devices using gallium arsenide, Recently, research and development has been carried out on the heteroepitaxial growth of gallium arsenide layers on silicon substrates. The reason is,
This is because silicon substrates are inexpensive, large-diameter substrates are available, and because they are strong, they are easier to handle than compound semiconductor substrates such as gallium arsenide and indium phosphorus.

There is a 4% difference in lattice constant between silicon and gallium arsenide.
In addition to the difference in thermal expansion coefficient of 230%, there is a difference in that although silicon crystals do not have polarity, gallium arsenide crystals do have polarity.
It is not easy to grow a defect-free gallium arsenide single crystal layer on a silicon substrate using conventional homoepitaxial growth methods.

For this purpose, two-step growth methods are employed, in which a thin amorphous gallium arsenide layer is first formed on a silicon substrate at low temperatures, this is heated to crystallize, and a gallium arsenide layer is grown on top of that, or an indium arsenide layer with a different lattice constant, for example. A method is used in which a gallium arsenide layer is grown through a strained superlattice consisting of a gallium arsenide layer and a gallium arsenide layer.

[Problems to be Solved by the Invention] The conventional method of growing a gallium arsenide layer on a silicon substrate is extremely complicated as described above, and
Despite the need for precise control of growth conditions, it is not always possible to obtain high-quality gallium arsenide crystals. In particular, the density of defects such as dislocation density occurring in the crystal is high. The surface morphology is poor. This is an obstacle to forming semiconductor devices on this gallium arsenide layer.

The purpose of the present invention is to eliminate these drawbacks,
An object of the present invention is to provide a semiconductor device formed on a gallium arsenide layer formed on a silicon substrate. More specifically, we developed a method for forming a high-quality gallium arsenide single crystal layer on a silicon substrate, in which defects such as dislocations are absorbed, the defect density is significantly reduced, and the surface morphology is good. The purpose is to provide distant relatives with the above purpose.

[Means to solve the problem]

The above purpose can be distantly related to any of the following means.

The first means (corresponding to claim [1]) is a silicon substrate (
11), a gallium arsenide layer (12) provided on this silicon substrate (11), and the aforementioned silicon substrate (11).
and a buffer layer containing gallium phosphide provided between the gallium arsenide layer (12) and the gallium arsenide layer (12).

A second means (corresponding to claim [2]) is the claim [1], wherein the buffer layer is a single gallium phosphide layer (13).
This is the semiconductor device described.

A third means (corresponding to claim [3]) is characterized in that the buffer layer is a superlattice (15) formed by laminating a gallium phosphide layer and a gallium arsenide layer. This is the semiconductor device described.

A fourth means (corresponding to claim [4]) provides that the buffer layer made of the superlattice (15) is formed on the underlying silicon substrate (
11) The semiconductor device according to claim 3, wherein the composition is rich in gallium phosphide, and the composition is sequentially rich in gallium arsenide toward the upper gallium arsenide layer (12).

A fifth means (corresponding to claim [5]) is characterized in that a second buffer layer (18) made of gallium phosphide is provided under the buffer layer made of the superlattice (15). 3] is the semiconductor device described.

A sixth means (corresponding to claim 6) is that the buffer layer made of the superlattice (15) has a composition with a large amount of gallium phosphide on the side of the lower gallium phosphide layer (16), and 6. The semiconductor device according to claim 5, wherein the composition gradually increases in gallium arsenide toward the gallium arsenide N (12) side.

A seventh means (corresponding to claim [7]) provides a second buffer layer (1) made of aluminum arsenide between the buffer layer made of the superlattice (15) and the silicon substrate (11).
7) is provided, the semiconductor device according to claim [3].

An eighth means (corresponding to claim [8]) provides a second buffer lli (
14) is provided, the semiconductor device according to claim [3].

A ninth means (corresponding to claim [9]) is a third buffer layer (corresponding to claim [9]) made of argonium arsenide or gallium phosphide between the second buffer layer (I4) and the silicon substrate (11). 16) is provided, the semiconductor device according to claim [8].

[Effect]

In the method for forming a gallium arsenide layer in which a semiconductor device (corresponding to claims [1] and [2]) according to the present invention is formed, a buffer layer is formed between the silicon substrate 11 and the gallium arsenide layer 12. N13 containing gallium phosphide is interposed. In this way, since the gallium phosphide crystal has the same lattice constant as that of the silicon crystal, the gallium phosphide layer 13 formed on the silicon substrate 11
In addition, since gallium phosphide crystals have polarity like gallium arsenide crystals, it is easier to grow island-like layers compared to the method of directly growing a gallium arsenide layer on the silicon substrate 11. This makes it possible to grow gallium arsenide Ji12 with good surface morphology.

Further, the semiconductor device according to the present invention (claims [3] and [4]
[5] [6] [7 Corresponding to [8] [9]) In the method for forming a gallium arsenide layer, (GaAs) is formed between the silicon substrate 11 and the gallium arsenide layer 12. , 1 (cap)s superlattice 1
It has been shown that a buffer layer consisting of 5 layers is interposed.

Then, the lattice constant of the (GaAs)ll (GaP) superlattice 15 is set to be an intermediate lattice constant between gallium phosphide and gallium arsenide, or the lattice constant is gradually changed from the lattice constant of gallium phosphide to that of gallium arsenide. It has been shown that by changing the structure, defects such as dislocations can be absorbed by the strained superlattice effect, and the defect density can be significantly reduced. Here, the superlattice of (C; aAs) and (GaP) is a superlattice formed by stacking multiple sets of n atomic layers of gallium arsenide and m atomic layers of gallium phosphide, The numbers representing the number of atomic layers in each of the n atomic layers and m atomic layers do not need to be fixed, and can be selected as desired. That is, in the region close to the silicon substrate 11, m is made thicker and Ln is made smaller, so that the characteristics of the set of n atomic layer of gallium arsenide and m atomic layer of gallium phosphide are made closer to those of gallium phosphide, and closer to those of gallium arsenide 1112. In the region, by increasing n and decreasing Lm, the characteristics of the set of n atomic layer of gallium arsenide and m atomic layer of gallium phosphide can be made close to that of gallium arsenide,
This is also effective for distantly achieving the object of the present invention.

Note that the buffer layer 13 containing gallium phosphide and (GaAs
), (GaP), a second buffer layer 18 made of gallium phosphide interposed between the superlattice 15 and the silicon substrate 11, and a second buffer layer 1 made of aluminum arsenide.
7. The second buffer layer 14 made of gallium arsenide has the property of blocking or absorbing defects, and also has the property of blocking or absorbing defects.
The aluminum arsenide layer used as the third buffer layer interposed between the buffer layers 18, 17, 14 and the silicon substrate 11 has a strong bond with silicon and has polarity, so gallium phosphorus It works effectively to improve surface morphology in the same way as a buffer layer containing .

〔Example〕

Hereinafter, six embodiments of a method for forming a gallium arsenide layer used for manufacturing a semiconductor device according to the present invention will be described with reference to the drawings.

See FIG. 2 FIG. 2 is a configuration diagram of a vapor phase growth apparatus used in a method for forming a gallium arsenide layer used to manufacture a semiconductor device according to the present invention. In the figure, 1 is a reaction chamber, 2 is an exhaust port, 3 is a pressure controller that controls the pressure in the reaction chamber, 4 is a supply gas switching valve, 5 is a heating high-frequency coil, and 6 is a susceptor that supports the silicon substrate If.

12, see FIG. 1(a), FIG. 3, and FIG. 4. FIG. 3 is a growth temperature profile showing the change over time in the temperature of the silicon substrate 11 during vapor phase growth. Fourth
The figure is a raw material gas supply pulse sequence showing changes over time in the amounts of various raw material gases supplied into the reaction chamber 1 during vapor phase conditioning.

The silicon substrate 11 is placed on the susceptor 6 of the vapor phase growth apparatus shown in FIG. 2, and the source gas (trimethylaluminum, trimethylgallium・Phosphine, arsine) is supplied into the reaction chamber 1 through the gas switching valve 4, and as shown in FIG. Next, the gallium phosphide layer 13 is grown by atomic layer epitaxial growth (hereinafter referred to as ALE epitaxial growth) to a thickness of about 30 nm, and the gallium arsenide layer 12 is grown by organic metal to a thickness of about 3 nm. Vapor phase growth (
Hereinafter, the temperature of the silicon substrate 11 at this time, which is referred to as MOCVD growth, is controlled by using the high frequency coil 5.
As shown in the figure, each growth step is controlled accordingly. The temperature of the bubbler is -3°C for trimethyl gallium.
For trimethylaluminum, the temperature may be -22°C.

The combination of gas supply amount and gas supply time of one pulse during ALE growth of the gallium phosphide layer is 403 CCM and 4 seconds for trimethyl gallium, and 4 seconds for phosphine (20%, H2 base). is 4803 CCM and 20 seconds.

Note that when switching the raw material gas to be supplied to the reaction chamber 1, it is preferable to supply hydrogen for about 3 seconds to perform purging.

When growing a gallium arsenide layer by MOCVD, 23 CCM of trimethyl gallium and 403 CCM of arsine (10%, H, base) are supplied to increase the growth rate to 2. In/h
shall be.

Note that the same effect can be obtained by forming an arsenic monoatomic layer in place of the aluminum monoatomic layer (not shown) described above.

The gallium arsenide layer 12 manufactured through the above steps has fewer defects. As described in the section of the function, gallium phosphide and silicon as the buffer layer 13 have roughly the same lattice constant, and gallium phosphide and gallium arsenide as the buffer layer 13 also have polarity. Because there is.

The number of stacked monoatomic layers of gallium phosphide is increased and the number of stacked monoatomic layers of gallium arsenide is decreased to obtain a composition with a large amount of gallium phosphide. It is more preferable to increase the number of stacked monoatomic layers of gallium phosphide to obtain a composition with a large amount of gallium arsenide.

2 34, see FIG. 1(b) The above gallium phosphide layer 13 may be replaced by a superlattice body 15 made of a laminate of a gallium phosphide layer and a gallium arsenide layer, as shown in FIG. 1(b). In this case, it is desirable that the layer in direct contact with the silicon substrate 11 be a gallium phosphide layer. This is because the lattice constant of gallium phosphide is substantially equal to that of silicon. On the other hand, the gallium arsenide layer 12
The layer in direct contact with the gallium arsenide layer is preferably a gallium arsenide layer, since they are the same compound.

Here, in the part near the silicon substrate 11, 3
56, in the second example (corresponding to claims [3] and [4]), see FIG. , for the same reason as above, the crystal state of the gallium arsenide layer 12 becomes even better.

In this example as well, the number of stacked monoatomic layers of gallium phosphide is increased in the portion close to the silicon substrate 11, and the number of stacked monoatomic layers of gallium arsenide is decreased to obtain a composition with a large amount of gallium phosphide, and the portion close to the gallium arsenide layer 12 is As in the case of the second example, it is more preferable to increase the number of stacked monoatomic layers of gallium arsenide and decrease the number of stacked monoatomic layers of gallium phosphide to obtain a composition with a large amount of gallium arsenide.

Moreover, since the gallium arsenide layer 12 has the property of not reaching N (the superlattice 15 in this example), the crystal state of the gallium arsenide layer 12 becomes even better.

4. In the second example (corresponding to claims [3] and [4]), see FIG. When provided, aluminum arsenic has the property of absorbing defects, and the defects are absorbed by the upper layer (
In this example, since it has the property of not reaching the superlattice 15), the crystal state of the gallium arsenide layer 12 becomes even better.

In the second example (corresponding to claims [3] and [4]) shown in FIG. When provided, gallium arsenide has the property of blocking defects. FIG. 6 is a growth temperature profile showing changes in temperature over time.
The figure is a raw material gas supply pulse sequence showing changes over time in the amounts of various raw material gases supplied during vapor phase lengthening.

The silicon substrate 11 is placed on the susceptor 6 of the vapor phase growth apparatus shown in FIG. 2, and the raw material gas is switched to pulp 4 using hydrogen as a carrier gas according to the raw material gas supply pulse sequence shown in FIG. The silicon substrate 1 is supplied into the reaction chamber 1 through the silicon substrate 1 as shown in FIG.
1, first, an aluminum arsenic layer is grown on the third buffer layer 16 to a thickness of about 300 nm, and then the second
After growing the gallium arsenide layer 14 as a buffer layer by MOCVD, the gallium arsenide layer 14 is made of a gallium arsenide layer and a gallium phosphide layer, and has a lattice constant between gallium arsenide and gallium phosphide (GaAs), (GaP), and a superlattice ( A layered stack of a monoatomic layer of gallium arsenide and a monoatomic layer of gallium phosphide) 15 is grown by ALE, and on top of that, a gallium arsenide layer 12 with a thickness of about 3n, which is used as an active layer, is grown by MOCVD. The temperature of the silicon substrate 11 at this time is controlled using the high frequency coil 5 in accordance with each growth process, as shown in FIG. Trimethylgallium is used as a raw material for gallium, trimethylaluminum is used as a raw material for aluminum, arsine is used as a raw material for arsenic, and phosphine is used as a raw material for phosphorus. °C and -22 °C for trimethylaluminum.

The aluminum arsenic layer 16 as the third buffer layer and the (GaAs), (GaP) 1 superlattice 15 as the buffer layer are The combinations are 403CCM and 4 seconds for trimethylgallium, 20SCCM and 7.5 seconds for trimethylaluminum, and 4803C for arsine (10%).
A combination of CM and 10 seconds is used, and a combination of 4803CCM and 20 seconds is used for phosphine (20%).

When switching the raw material gas supplied to the reaction chamber 1, hydrogen is supplied for 3 seconds for purging.

For MOCVD growth of the gallium arsenide layer as the second buffer layer 14 and the gallium arsenide layer 12 as the active layer, trimethylgallium 43CCM and arsine 11
005CC and the growth rate is set to 2.1 u/h.

Note that a gallium phosphide layer may be formed as the third buffer layer 16 instead of the aluminum arsenide layer.

The gallium arsenide layer 12 manufactured in this manner has an extremely good crystalline state and has few defects. This is because all of the effects specific to each of the embodiments described above function additively.

〔Effect of the invention〕

As explained above, in the method for forming a gallium arsenide layer used for manufacturing a semiconductor device according to the present invention, prior to growing a gallium arsenide layer on a silicon substrate, the lattice constant is different from that of silicon. Equally, and
A buffer layer made of gallium phosphide having polarity similar to gallium arsenide is interposed, or a buffer layer made of a superlattice whose lattice constant has an intermediate value between silicon and gallium arsenide, or silicon Because a buffer layer consisting of a superlattice whose lattice constant gradually changes from that of gallium arsenide to that of gallium arsenide is interposed, the surface morphology is good and defects such as dislocations are absorbed, greatly reducing the defect density. A high quality gallium arsenide single crystal layer is formed on a silicon substrate. In this way, a semiconductor device formed in a gallium arsenide single crystal layer with a low defect density and good surface morphology using a silicon substrate as a base material has extremely good characteristics.

[Brief explanation of drawings]

Figure 1(a), Figure 1(b), Figure 1(c), Figure 1(d)
), FIG. 1(e), and FIG. 1(f) illustrate the first embodiment (corresponding to claim [2]) and the second embodiment (corresponding to claim [2]) of the present invention, respectively.
(corresponding to claims [3] [4]), third embodiment (corresponding to claims [5] [6]), and fourth embodiment (corresponding to claims [7]
FIG. 4 is a cross-sectional view of a semiconductor substrate used in a semiconductor device according to a fifth embodiment (corresponding to claim [8]), a sixth embodiment (corresponding to claim [9]), and a sixth embodiment (corresponding to claim [9]). FIG. 2 is a block diagram of an apparatus used in a method for forming a gallium arsenide layer used to manufacture a semiconductor device according to the present invention. FIG. 3 is a growth temperature profile of a method for forming a gallium arsenide layer used to manufacture a semiconductor device according to a first embodiment of the present invention. FIG. 4 is a raw material gas supply pulse sequence of a method for forming a gallium arsenide layer used to manufacture a semiconductor device according to the first embodiment of the present invention. FIG. 5 is a growth temperature profile of a method for forming a gallium arsenide layer used to manufacture a semiconductor device according to a sixth embodiment of the present invention. FIG. 6 is a source gas supply pulse sequence of a method for forming a gallium arsenide layer used to manufacture a semiconductor device according to a sixth embodiment of the present invention. 16... Third buffer N (aluminum arsenide or gallium phosphide layer), 17... Second buffer layer (aluminum arsenide N),
18... Second buffer layer (gallium phosphide layer).

Claims (1)

[Claims] [1] A silicon substrate (11), a gallium arsenide layer (12) provided on the silicon substrate (11), and a combination of the silicon substrate (11) and the gallium arsenide layer (12).
) and a buffer layer containing gallium phosphide. [2] The buffer layer is a single-layer gallium phosphide layer (13
) The semiconductor device according to claim 1, characterized in that the semiconductor device comprises: [3] The semiconductor device according to claim 1, wherein the buffer layer is a superlattice (15) formed by laminating a gallium phosphide layer and a gallium arsenide layer. [4] The buffer layer made of the superlattice (15) has a composition in which gallium phosphide is abundant on the lower layer silicon substrate (11) side, and gallium phosphorus is gradually added toward the upper layer gallium arsenide layer (12) side. 4. The semiconductor device according to claim 3, wherein the composition changes to a composition containing a large amount of arsenic. [5] The semiconductor device according to claim 3, wherein a second buffer layer (18) made of gallium phosphide is provided below the buffer layer made of the superlattice (15). [6] The buffer layer made of the superlattice (15) has a composition in which gallium phosphide is rich on the side of the lower gallium phosphide layer (16), and the composition is sequentially increased toward the side of the upper gallium arsenide layer (12). 6. The semiconductor device according to claim 5, wherein the composition changes to include a large amount of gallium arsenide. [7] A second buffer layer (17) made of aluminum arsenic is provided between the buffer layer made of the superlattice (15) and the silicon substrate (11). 3]. The semiconductor device described in [3]. [8] A second layer made of gallium arsenide is provided between the buffer layer made of the superlattice (15) and the silicon substrate (11).
4. The semiconductor device according to claim 3, further comprising a buffer layer (14). [9] The second buffer layer (14) and the silicon substrate (
11). The semiconductor device according to claim 8, further comprising a third buffer layer (16) made of aluminum arsenide or gallium phosphide.