JPS6276792A - Semiconductor device - Google Patents

Abstract

PURPOSE:To prevent the characteristic of a semiconductor device from deteriorating by forming a GaAs layer adjacently on a AlGaAs layer of the thickness of 500Angstrom to 1mum, and forming the device including at least two sets of layers. CONSTITUTION:In a semiconductor device that FETs are, for example, integrated, a P-type AlGaAs clad layer 2, a GaAs active layer 3, an N-type AlGaAs clad layer 4 and an N-type GaAs cap layer 5 are laminated on a P-type GaAs substrate 1 to form a semiconductor laser A. A buffer layer 6, an a-type GaAs layer 7 are laminated thereon, and FET B is formed by the layer 7. The layer 6 is formed by alternately growing non-doped AlGaAs layer 21 of 500Angstrom -1mum thick and non-doped GaAs layer 22 formed adjacently thereon. If the AlGaAs layer is 500Angstrom or less, the surface is roughened, and if it exceeds 1mum, the surface roughness cannot be improved even by the GaAs layer.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a semiconductor device, and particularly to a thin film semiconductor device having a stacked structure.

(Prior art) In recent years, semiconductor thinning technology has been developed using molecular beam epitaxy (MBE).
Rapid technological innovations are being made through research into new methods such as MO-CVD (method) and metal-organic chemical vapor deposition (MO-CVD), and these technologies are capable of making semiconductors ultra-thin, which was impossible with conventional techniques. This enabled uniform growth over a large area. Also,
Taking advantage of these features, we are improving the performance of conventional devices and proposing new devices, which are seen as promising for the future.

Currently, most of the fields that utilize these semiconductor thinning technologies are compound semiconductor technology fields. Typical materials include (GaAs, AuGaA
s) (InGaAsP.

Examples include materials such as A-pattern GaInP). When such a material is grown by MBE, MO-CVD, etc., the surface of the grown film may become rough under certain growth conditions. FIG. 4 is a diagram showing the formation of a conventional thin film. 42 is a substrate of GaAs, and 43 is a grown film of AlGaAs. When A1GaAs film is grown using the MBE method, the substrate temperature (Tsub) is 680°C to 75°C.
The AfLGaAs surface becomes rough at about 0°C. However, this substrate temperature also differs depending on the individual equipment, so there will be some deviation depending on the equipment.
) ratio and growth rate is small.

The surface roughness of the grown film is as follows for AlGaAs film:
Normally, if the thickness is less than 3000 Å, unevenness on the growth surface cannot be confirmed, but if it exceeds 5000 Igm, it can be confirmed with the naked eye due to phenomena such as clouding of the AfLGaAs surface. It was also confirmed that the unevenness on the AfLGaAs surface i increases as the thickness increases.

This surface roughness poses problems in the following points.

■Obstructs the device formation process ■Degrading the characteristics of the created element etc.

As described above, the surface condition of the grown film has a great influence on the device, and it becomes a big problem that the grown film cannot be obtained in a range that is considered optimal for device formation.

Therefore, attempts have been made to improve the surface of semiconductor grown films by changing the growth conditions or by inserting a superlattice structure into the semiconductor stack, but satisfactory results have not yet been obtained.

(Summary of the Invention) An object of the present invention is to prevent surface roughening of a semiconductor grown film and provide a semiconductor device with excellent characteristics.

The above object of the present invention is achieved by a semiconductor device including at least two or more sets of an AMGaAs layer with a thickness of 500 Å or more and 1 gm or less 1 and a GaAs layer formed adjacent to the AlGaAs layer.

That is, in the present invention, when forming a thick AfLGaAs layer, the surface roughness caused by AlGaAs is improved by sandwiching the GaAs layers at intervals of 500 Å or more and 1 gm or less.

Since the surface of the AfLGaAs layer begins to become rough after 500 people, the above-mentioned spacing is meaningless if it is less than 500 Å.

Moreover, when the thickness of the AfLGaAS layer exceeds Igm, Ga
Even by laminating As layers, the surface roughness cannot be completely improved. The thickness of the GaAs layer is preferably 500-0 Å.
The thickness is preferably 3000 Å or less. GaA
If the thickness of the s layer is 50 Å or more, surface roughness can be sufficiently improved.

(Example) Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a schematic cross-sectional view showing a first embodiment in which the present invention is applied to a semiconductor device in which a semiconductor laser and a field effect transistor (hereinafter referred to as FET) are integrated. In Fig. 1, 1 is a p-type GaAs substrate, on which p-type A1GaA
s cladding layer 2, GaAs active layer 3, n-type AlGaAs
A cladding layer 4 and an n-type GaAs cap layer 5 are laminated to form a semiconductor laser section A. Furthermore, a buffer layer 6 and an n-type GaAs layer 7 are laminated thereon, and the FET section B is formed using the n-type GaAs layer 7. 9゜10.11 is FET
12 is an electrode of a semiconductor laser, and 8 is an insulating layer 5i02. The semiconductor laser section A is driven under the control of the FET section B and emits laser light from the light emitting section 13.

The buffer layer 6 is for electrically separating the semiconductor laser part A and the FET part B, and in this embodiment, this part is
It has a multilayer structure of lGaAs and GaAs.

FIG. 2 shows the actual structure of the buffer layer 6.

The buffer layer 6 is made of non-doped AM, G with a thickness of 3000 mm.
It is formed by alternately and repeatedly growing an aAS layer 21 and a non-doped GaAs layer 22 with a thickness of 500 nm formed adjacent thereto. A4uGaAs exhibits a high resistance of about 107 Ωcm'' without doping with impurities, making it suitable for isolation between elements. However, as mentioned above, when AiGaAs is grown thickly, the growth surface becomes rough. In this example, the growth surface becomes rough. 3000 to
By sandwiching the GaAs layers at intervals, a buffer layer 6 with excellent insulation properties was obtained while keeping the growth surface flat. Further, in FIG. 2, a device was formed as a buffer layer 6 by changing the repetition period of the semiconductor layer and growing a non-doped AfLGaAs layer 21 of 5000 layers and a non-doped GaAs layer 22 of 1000 layers alternately, which was also described above. It worked well, as did the previous example.

FIG. 3 is a schematic cross-sectional view showing a second embodiment in which the present invention is applied to a semiconductor laser. In FIG.
Then, two sets of n-type GaAs 33 with a thickness of 200 layers were alternately laminated, and an n-type AflGaAs layer 32 with a thickness of 600 OA was grown to form the next cladding layer 40.

An n-type GaAs active layer 34 is formed on this cladding layer 40, and a p-type cladding layer 41. A p-type GaAs cap layer 37 was laminated to form a semiconductor laser. Here, the cladding layer 41 is also formed by growing a p-type AlGaAs layer 35 with a thickness of 6000 on the active layer, and further growing a p-type AlGaAs layer 35 with a thickness of 2000 on top of this.
0.0 nm pWGaAs layer 36 and 3000 nm thick P-type Al
It is made by laminating two sets of GaAs layers 35 alternately. 38 is an insulating layer, 39 is an electrode, and 30 is a light emitting part.

In this embodiment, A or GaAs adjacent to the active layer 34 is used.
The reason why the layer is thicker than other parts is because of the G in the cladding layer.
This is because if the aAs layer is too close to the active layer, it may absorb light.

In this example, the interface between the cladding layer 40 and the active layer 34 was improved by the above structure, and a long-life semiconductor laser with few interface states could be formed. Furthermore, the surface of the cap N37 is flattened by the cladding layer 41 having a multilayer structure,
Problems caused by surface irregularities during the fabrication process have been resolved.

The present invention is not limited to the above embodiments.

It can be applied to various semiconductor devices using A l (ra As).

(Effects of the Invention) As explained above, the present invention comprises at least two or more sets of A-type GaAs layers having a thickness of 500 Å or more and 1 lumen or less, and GaAs layers formed adjacent to each other on the AJljGaAS layer. Since the semiconductor device is constructed by including the semiconductor device, the characteristics of the device do not deteriorate, and there is an effect of preventing failures in the device formation process.

[Brief explanation of drawings]

FIG. 1 is a schematic cross-sectional view showing a first embodiment of the present invention, FIG. 2 is a partial cross-sectional view explaining the structure of the buffer layer in FIG. 1, and FIG. 3 is a schematic cross-sectional view showing a second embodiment of the present invention. 4 is a schematic cross-sectional view showing the growth of a conventional semiconductor layer. 5--n-type GaAs cap layer, 6--buffer layer, 71--n-type GaAs layer, 21-
--/y doped AMGaAs layer, 22---/7 doped GaAs layer.

Claims (2)

[Claims] (1) A semiconductor device configured by stacking semiconductors, wherein the semiconductor includes at least two sets of an AlGaAs layer with a thickness of 500 Å or more and 1 μm or less, and a GaAs layer formed in contact with the AlGaAs layer. A semiconductor device characterized by: (2) The semiconductor device according to claim 1, wherein the GaAs layer has a thickness of 50 Å or more.