CN101192517A - Fabrication method of multi-layer deformation buffer layer on gallium arsenide substrate - Google Patents

Abstract

The invention relates to a method for manufacturing multilayer buffer layers with deformation on a gallium arsenide substrate. The invention is characterized in that the method comprises the following steps: step 1, one gallium arsenide substrate is extracted; step 2, the gallium arsenide substrate is processed by deoxidation; step 3, the buffer layers of the gallium arsenide are generated on the gallium arsenide substrate so as to obtain a flat surface; step 4, a buffer layer of indium aluminum arsenic is generated in a range of relatively low temperature, and the buffer layer of the indium aluminum arsenic has a one-layer, two-layer or multi-layer structure so as to achieve the change of lattice constant in the process of epitaxial growth; and step 5, after the buffer layer of the indium aluminum arsenic is generated, the temperature of the gallium arsenide substrate is increased, and high temperature annealing is carried out so as to release the stress of an epitaxial layer.

Description

Fabrication method of multi-layer deformation buffer layer on gallium arsenide substrate

technical field

The invention relates to the field of crystal epitaxial growth, in particular to a method for manufacturing a multi-layer deformation buffer layer on a gallium arsenide substrate.

Background technique

Gallium arsenide (GaAs) substrate has been widely used in the fields of microelectronics and optoelectronics for growing light-emitting diodes (LEDs), lasers, etc. Diodes (LD), optical communication active devices, solar cells, microwave devices, etc. Recently, in order to quickly process massive amounts of information that triples every year, the world's rapid development of optical fiber communications, the Internet, and mobile communications requires the preparation of materials to develop in the direction of high frequency, high bandwidth, and high transmission speed. This requires the grown material to have higher mobility, but usually there is a large gap between the epitaxial material (such as high indium composition indium gallium arsenide (InGaAs) and the gallium arsenide (GaAs) substrate. The lattice mismatch, so the technology of adding a buffer layer between the substrate and the active region has become a key technology for making gallium arsenide-based semiconductor materials. As a buffer layer, there are two main functions. On the one hand, it compensates the substrate and the lattice mismatch between the active region, on the other hand, it can filter the dislocations caused by the lattice mismatch. Therefore, the growth of a buffer layer with high flatness, few defects, and precise composition is very important for the production of semiconductor optoelectronic materials It is very important. In addition, in the field of microelectronic device integration, there is a high requirement for the insulation performance of the materials used in semiconductor devices. This proposes the method of growing a high-resistance buffer layer to avoid the difficulties caused by the leakage of the buffer layer to device integration. The present invention is proposed in order to meet the above requirements.

Contents of the invention

The object of the present invention is to provide a method for manufacturing a multi-layer deformation buffer layer on a gallium arsenide substrate, which can improve the quality of the crystal and facilitate the manufacturing of subsequent process steps.

A method for manufacturing a multi-layer deformation buffer layer on a gallium arsenide substrate of the present invention is characterized in that it comprises the following steps:

Step 1: Take a gallium arsenide substrate;

Step 2: Deoxidize the gallium arsenide substrate;

Step 3: growing a gallium arsenide buffer layer on the gallium arsenide substrate to obtain a flat surface;

Step 4: growing an InAlAs buffer layer in a low temperature range, the InAlAs buffer layer has a one-layer, two-layer or multi-layer structure, so as to achieve the change of the lattice constant during the epitaxial growth process;

Step 5: After growing the InAlAs buffer layer, increase the temperature of the GaAs substrate and perform high-temperature thermal annealing to release the stress of the epitaxial layer.

Wherein, when the indium aluminum arsenic buffer layer is one layer, the indium aluminum arsenic buffer layer is a structure in which the linear indium composition gradually increases; when the indium aluminum arsenic buffer layer is two layers, the indium aluminum arsenic buffer layer is a linear indium composition The structure of the buffer layer is gradually increased and reversed; when the indium-aluminum-arsenic buffer layer is multi-layered, the indium-aluminum-arsenic buffer layer has a stepped indium composition graded structure.

Wherein the deoxidation treatment in step 2 is carried out at 500-650°C.

The growth temperature of the gallium arsenide buffer layer is 550-700° C.; the growth thickness is 10-1000 nanometers to obtain a flat surface.

The growth temperature of the indium aluminum arsenic buffer layer is 250-420° C., which prevents the three-dimensional growth of the indium aluminum arsenic material caused by the growth temperature being too high.

The indium composition x in the IAlAs buffer layer varies from 1-30% to 30-100%, so as to ensure the lattice matching of the epitaxial material grown subsequently.

The thickness of the InAlAs buffer layer is between 200 nanometers and 5 micrometers, so as to reduce the stress caused by lattice mismatch.

When growing multiple layers of InAlAs buffer layer, the method of pausing growth is adopted, that is, after the growth of each layer of InAlAs buffer layer is completed, stop for 1-5 minutes, and then grow the next layer of buffer layer.

The indium composition difference between each layer of the multi-layer InAlAs buffer layer is between 1-30%, and the thickness is between 10-500 nanometers.

Wherein, when the indium aluminum arsenic buffer layer is one layer, the thickness of the indium aluminum arsenic buffer layer is 1-5 microns.

Wherein the InAlAs buffer layer has two layers, the difference in indium composition between the two layers of the InAlAs buffer layer is in the range of 1-50%.

The annealing temperature mentioned therein is 470° C.-520° C., and the annealing time is 0-60 minutes.

Description of drawings

In order to further illustrate the specific technical content of the present invention, below in conjunction with embodiment and accompanying drawing detailed description as follows, wherein:

FIG. 1 is a first embodiment of the present invention, which shows a schematic structural view of a multi-layer InAlAs buffer layer;

Fig. 2 is a second embodiment of the present invention, which shows a schematic structural view of an indium aluminum arsenic buffer layer;

3 is a third embodiment of the present invention, which shows a schematic structural view of two InAlAs buffer layers;

Fig. 4 is a schematic diagram of a deformed high electron mobility transistor structure fabricated by the first embodiment of the present invention;

FIG. 5 is a high-resolution three-axis X-ray diffraction curve of an InAlAs buffer layer according to Embodiment 1 of the present invention.

Detailed ways

First please refer to Fig. 1, Fig. 2 and Fig. 3, the method for manufacturing a multi-layer deformation buffer layer on a gallium arsenide substrate of the present invention is characterized in that it comprises the following steps:

Firstly, a gallium arsenide substrate 11 is taken and put into an ultra-high vacuum molecular beam epitaxy growth chamber. The gallium arsenide substrate 11 is deoxidized by increasing the sinking temperature to 500-650° C. to obtain a flat epitaxial surface. Then, at a substrate temperature of 550-700° C., a gallium arsenide buffer layer 12 with a thickness of 10-1000 nm is grown to obtain a flat surface and provide an advantageous epitaxial layer. Then the growth of the InAlAs buffer layer 13 is completed within the temperature range of 250-420°C. In this temperature range, the three-dimensional growth of the InAlAs buffer layer material at high temperature is prevented, that is, it grows into a quantum dot structure, and it is ensured that in the selected temperature range, the InAlAs atoms have sufficient surface migration to form Flat epitaxial surface. After growing the InAlAs buffer layer 13, raise the substrate temperature to 470°C-520°C, and perform high-temperature thermal annealing in the furnace, and the annealing time is 0-60 minutes. The purpose of annealing is to release the stress in the grown epitaxial layer due to the difference in lattice constant with the substrate.

The grown indium-aluminum-arsenic buffer layer 13 is a buffer layer 13' (Fig. 2) with a graded indium composition, a two-layer buffer layer 13" (Fig. 3) or a multi-layer buffer layer 13 (Fig. 1) structure. Wherein the When the indium aluminum arsenic buffer layer 13' is one layer, the indium aluminum arsenic buffer layer 13' is a structure in which the indium composition increases gradually; when the indium aluminum arsenic buffer layer 13" is two layers, the indium aluminum arsenic buffer layer 13" is a buffer layer structure in which the linear indium composition gradually increases and reverses; when the indium-aluminum-arsenic buffer layer 13 is multi-layered, the indium-aluminum-arsenic buffer layer 13 has a stepped indium composition gradient structure, and the indium composition x Variation range changes between 1-30% to 30-100%, to guarantee the lattice matching of the epitaxial material of follow-up growth.The total thickness of indium aluminum arsenic buffer layer 13 is between 200 nanometers-5 microns, to reduce The stress generated by the lattice mismatch and filters the dislocations generated in the lattice mismatched epitaxially grown material.

When growing the multi-layer InAlAs buffer layer 13, the method of pausing growth is adopted, that is, after the growth of each layer of InAlAs buffer layer 13 is completed, pause for 1-5 minutes, and at the same time ensure that the molecular beam epitaxy growth chamber is connected to the arsenic beam. To protect the grown InAlAs buffer layer. Then grow the next buffer layer until all the InAlAs buffer layer 13 structures are grown.

When the grown indium aluminum arsenic buffer layer 13 is a multilayer structure, the difference in indium composition between each layer is between 1-30%, the thickness of each layer is between 10-500 nanometers, and the overall thickness is 1 -5 microns. Ensure that the grown InAlAs buffer layer 13 has sufficient thickness to relieve stress. When the grown InAlAs buffer layer 13 has two layers, the difference in indium composition between the two layers is in the range of 1-50%, which is used to change the stress on the epitaxial layer. Since the lattice constant of the InAlAs buffer layer 13 is greater than the lattice constant of the GaAs substrate, and the lattice constant becomes larger with the increase of the indium component in the buffer layer, the grown epitaxial layer is pressed by the substrate. Stress, when growing the second layer, the indium composition decreases, and the lattice constant decreases so that the second buffer layer is subjected to the tensile stress of the first buffer layer. Combining the two different stresses can make the entire buffer layer in a state of no stress or less stress, so as to improve the crystal quality of the buffer layer 13 .

Here is an example to illustrate,

Taking the gallium arsenide-based modified high electron mobility transistor (MMHEMT) material as an example, a stepped indium aluminum arsenic buffer layer structure with a gradient indium composition is adopted, and the channel layer is made of indium gallium arsenide (In0.52Ga0.48As) material.

As shown in FIG. 4 , a GaAs buffer layer 11 is deposited on a semi-insulating GaAs substrate by molecular beam epitaxy. The thickness of the buffer layer is about 150 nanometers, and the growth temperature is 580° C.

As shown in FIG. 4 , keep the As source furnace open and lower the substrate temperature to 30° C. to grow the InxAl ₁ -xAs buffer layer.

As shown in FIG. 4, the InxAl ₁ -xAs buffer layer 13 is composed of five layers 41-45. The variation range of the In composition is 0.1-0.53, and the thickness of each layer is 100 nanometers. After the growth of each layer is completed, the As source furnace is kept open for 5 minutes.

As shown in Fig. 4, InGaAs quantum well HEMT structures 51-55 are grown on the InxAl ₁ -xAs buffer layer, and the growth temperature is 480°C. It includes an In _0.52 Ga _0.48 As channel layer 51 , an In _0.53 Al _0.47 As isolation layer 52 , a Siδ doped layer 53 , an In _0.52 Al _0.48 As barrier layer 54 , and an In _0.52 Ga _0.48 As cap layer 55 .

As shown in Figure 5, the high-resolution X-ray triaxial diffraction curve of the multi-layer InxAl ₁ -xAs buffer layer can be clearly distinguished that each layer of buffer layer has its own diffraction peak, indicating that the multi-layer buffer layer structure we grew Accurate and good quality.

As shown in Table 1, the analysis of the Hall test results of the multi-layer InxAl ₁ -xAs buffer layer shows that the resistivity is 2.6×104 (ohm×cm) at room temperature. It is proved that the grown buffer layer material has a high resistivity, which fully meets the needs of device integration.

Table 1

Growth temperature (℃) Resistivity (Ω-cm) Hall factor Carrier concentration (cm ^-3 ) Mobility (cm ² /VS) 340 2.6×10 ⁴ 0.9946 5.319×10 ¹⁰ 4522

Claims (12)

1. a method for making a multilayer deformable buffer layer on a gallium arsenide substrate, characterized in that, comprising the steps: Step 1: Take a gallium arsenide substrate; Step 2: Deoxidize the gallium arsenide substrate; Step 3: growing a gallium arsenide buffer layer on the gallium arsenide substrate to obtain a flat surface; Step 4: growing an InAlAs buffer layer in a low temperature range, the InAlAs buffer layer has a one-layer, two-layer or multi-layer structure, so as to achieve the change of the lattice constant during the epitaxial growth process; Step 5: After growing the InAlAs buffer layer, increase the temperature of the GaAs substrate and perform high-temperature thermal annealing to release the stress of the epitaxial layer. 2. The method for manufacturing a multilayer deformable buffer layer on a gallium arsenide substrate according to claim 1, wherein when the indium aluminum arsenide buffer layer is one layer, the indium aluminum arsenide buffer layer is a linear indium arsenide buffer layer The composition gradually increases; when the indium-aluminum-arsenic buffer layer is two layers, the indium-aluminum-arsenic buffer layer is a buffer layer structure in which the indium composition gradually increases and reverses; the indium-aluminum-arsenic buffer layer is a multilayer In this case, the InAlAs buffer layer has a stepped indium composition graded structure. 3. The method for fabricating a multi-layer deformation buffer layer on a gallium arsenide substrate according to claim 1, wherein the deoxidation treatment in step 2 is performed at 500-650°C. 4. The method for manufacturing a multilayer deformable buffer layer on a gallium arsenide substrate according to claim 1, wherein the growth temperature of the gallium arsenide buffer layer is 550-700°C; the growth thickness is 10-1000 nano for a flat surface. 5. The method for manufacturing a multi-layer deformable buffer layer on a gallium arsenide substrate according to claim 1, wherein the growth temperature of the indium aluminum arsenide buffer layer is 250-420°C, which prevents the indium aluminum arsenide material Three-dimensional growth caused by excessive growth temperature. 6. The method for fabricating a multilayer deformable buffer layer on a gallium arsenide substrate according to claim 1, wherein the indium composition x in the indium aluminum arsenide buffer layer varies from 1-30% to 30- 100% to ensure the lattice matching of the subsequently grown epitaxial material. 7. The manufacturing method of the multilayer deformation buffer layer on the gallium arsenide substrate according to claim 1, wherein the thickness of the indium aluminum arsenide buffer layer is between 200 nanometers and 5 microns, so as to reduce the deformation caused by Stress due to lattice mismatch. 8. The manufacturing method of the multilayer deformation buffer layer on the gallium arsenide substrate according to claim 1, characterized in that, when growing the multilayer indium aluminum arsenide buffer layer, the method of pausing growth is adopted, that is, at each After the growth of the InAlAs buffer layer is completed, stop for 1-5 minutes, and then grow the next layer of buffer layer. 9. The method for manufacturing a multilayer deformable buffer layer on a gallium arsenide substrate according to claim 1, wherein the indium composition between each layer of the multilayer indium aluminum arsenide buffer layer The difference is between 1-30%, and the thickness is between 10-500 nanometers. 10. The method for manufacturing a multilayer deformable buffer layer on a gallium arsenide substrate according to claim 1, wherein when the indium aluminum arsenide buffer layer is one layer, the thickness of the indium aluminum arsenide buffer layer is 1-5 microns. 11. The method for manufacturing a multi-layer deformable buffer layer on a gallium arsenide substrate according to claim 1, characterized in that, when the indium aluminum arsenide buffer layer has two layers, the two layers of the indium aluminum arsenide buffer layer The layer indium composition difference is in the range of 1-50%. 12. The method for fabricating a multi-layer deformation buffer layer on a gallium arsenide substrate according to claim 1, wherein the annealing temperature is 470°C-520°C, and the annealing time is 0-60 minutes.

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