JPS6090900A - Method for diffusing impurity into compound semiconductor - Google Patents

Abstract

PURPOSE:To diffuse an impurity on the surface of a substrate by elevating the temp. of a compd. semiconductor substrate in a furnace, and introducing the vapor of an activated impurity element combined with hydrocarbon along with an ambient gas. CONSTITUTION:A GaAs substrate 13 is placed on a graphite susceptor 11a, and inserted into a diffusion furnace 11. After the atmosphere in the furnace is replaced with an inert gas, hydrogen is supplied from an introducing port 14. After the susceptor 11a is heated to about 500 deg.C by impressing a high-frequency power to a coil 12, AsH3 is supplied from a vessel 15 through a mass flowmeter 18. When the temp. of the susceptor 11a is further increased to a specified diffusion temp., H2 is supplied into a bubbler 16 to vaporize Zn(C2H5)2 17 which is supplied into the diffusion furnace 11. The Zn can be easily diffused on the surface of the GaAs substrate 13 in this way.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to gallium arsenide (GaAs), indium phosphide (NP), indium autologous gallium arsenide (I
Zinc (zn) on the surface of a compound semiconductor substrate such as nGaAs)
, relates to a method of diffusing impurities such as cadmium (Ca).

[Prior art]

Conventionally, the following methods have been used to diffuse impurities such as Zn and Cd onto the surface of +U-V group compound semiconductor substrates represented by GaAs and ■nP. As an example, as shown in Figure 1, first, G
aAs substrate (21 and Z n (31 and As
After inserting +41 and creating a high vacuum inside ampoule +11,
The opening of the ampoule [11 is fused, and then this ampoule (
1) in a diffusion furnace (
61 for a predetermined period of time, zn was diffused onto the surface of the GaAs substrate (2).

In the ampoule (1) inserted into the high-temperature furnace (6), Z n 131 is vaporized and a part of it is deposited on the GaAs substrate (
2) and diffuses into the substrate +21. Here, the A8+41 sealed in the ampoule serves to prevent the surface of the GaAs substrate (2) from decomposing due to high temperatures.

In this way, in the conventional impurity diffusion method, the GaAs substrate (2), Zn[:ll and As+41 are placed in an ampoule made of stone or English, the ampoule flj is placed in a high vacuum, and then the ampoule is removed. It was necessary to fuse the i11 opening. The size of the opening of the ampoule (1) is GaAl
1 Due to the workability of inserting and fusing the substrate (2), etc., it is possible to make the diameter only about 20 to 30 mm at most, which is larger than the opening of the ampoule f11 as the GaAs substrate (2) to be diffused. I couldn't use anything.

Furthermore, in the conventional impurity diffusion method, it was necessary to accurately weigh Znf 31 and As (41) to be sealed together with the GaAs substrate (2) to be diffused.

[Overview of the invention]

This invention was made in view of the above points, and uses hydrocarbons of impurity elements that have a high vapor pressure at room temperature and whose amount can be controlled as impurity materials to be diffused, and uses them in a diffusion furnace. This is a simple impurity diffusion method that does not have any restrictions on the size or number of semiconductor substrates by accommodating only the compound semiconductor substrate that is the target of impurity diffusion and allowing the diffusion to occur under the required atmosphere in an open state without sealing it. It provides:

[Embodiments of the invention]

FIG. 2 is a schematic sectional view showing a flow collecting situation in an embodiment of the present invention, in which (11) is a quartz diffusion furnace, (lla) is a graphite susceptor installed therein, and (121 is a graphite susceptor ('). 1la) is a coil for high-frequency heating, 03) is a GaAθ substrate which is a compound semiconductor placed on a graphite susceptor (121), (14) is an inlet for hydrogen (N2) which is an atmospheric gas, and (+51 is G
A container containing arsine (AθH3) to prevent thermal decomposition of the aAs substrate (131), 0@ is Bapla, 0η is Bapla (II) containing diethyl zinc (Zn (Zn), which is a hydrocarbonate of Zn as an impurity). C2H5)2], (
18+ is a mass flow controller that automatically controls each gas flow rate, and H is an exhaust port of the diffusion furnace (11).

Since zn(C2H5)2(I7) is a liquid, it is stored in badge fII and used by being vaporized with N2. The impurity diffusion method of this embodiment is carried out in the following steps.

First, a GaAs substrate (I) to be subjected to impurity diffusion is placed on a graphite susceptor (lla).Next, this graphite susceptor (lla) is inserted into a diffusion furnace (11), and a person and the furnace atmosphere are heated. After replacing the gas with an inert gas such as nitrogen (N2), N2 is supplied.Next, high frequency power is applied to the coil (121) to heat the susceptor (lla). When the temperature rises to 0, AsH3 is supplied from the container (15) through the mass 70-controller end.Furthermore, the temperature of the susceptor (lla) is raised, and when the predetermined diffusion temperature is reached, the bubbler is immediately turned off with N.
2 to vaporize Zn(C2H5)2(Iη and supply it to a diffusion furnace (++l).
s) The supply of 207) is stopped, and the application of high frequency power to the coil θ is stopped.

When the temperature of the susceptor (lla) falls below 500℃,
Stop the supply of AsH3 from the container +15], and when it reaches room temperature, replace the inside of the diffusion furnace (Ill with inert gas,
Take out the susceptor (lla) and take out the GaA B substrate 03).

This completes the diffusion process of this example.

Although the above example shows the case where Zn is diffused into a GaA a substrate, the substrate may also be an 111-V group compound semiconductor or an n-2 group compound semiconductor such as nP.

In addition, as an impurity, trimethylcadmium [Ca(C
H3)2] Teethyltellurium [Te(C2H6)2] or the like may be used.

In the above example, the substrate was heated by applying high frequency power to the graphite susceptor, but a resistance heating diffusion furnace may also be used.

〔Effect of the invention〕

As described above, according to the present invention, in the method for diffusing active impurities into a compound semiconductor, a hydrocarbon of an impurity element having a vapor pressure at room temperature is used as an impurity source.
The feeding wound is easy to control and continuous feeding is possible. Therefore,
Unlike conventional methods, there is no need to confine the weighed diffusion impurity substance together with the semiconductor substrate in a quartz ampoule each time diffusion is performed. Only the semiconductor substrate is placed in the diffusion furnace, and the impurity source is Diffusion is possible by continuing to supply it from the outside. As described above, this method is extremely simple compared to conventional methods, and impurities can be diffused without restrictions on the size or number of semiconductor substrates.

[Brief explanation of the drawing]

FIG. 1 is a schematic cross-sectional view showing the state of implementation of conventional diffusion of impurities into a compound semiconductor, and FIG. 2 is a schematic cross-sectional view showing the state of implementation of one embodiment of the present invention. In the figure, (the river is the furnace (diffusion 'fp), (+21 is the high-frequency heating coil, (131 is the compound semiconductor substrate, θ
4) is an atmospheric gas (H2) inlet, diarrhea is a container for a material to inhibit thermal decomposition, (16+ is a badge, and θ is a hydrocarbon impurity element. Agent: Masuo Oiwa)

Claims (1)

[Claims] +11 A compound semiconductor substrate is housed in a furnace and heated, and a vapor of a hydrocarbon of an active impurity element to be diffused into the compound semiconductor substrate is introduced into the furnace together with an atmospheric gas, Method 0 of impurity diffusion into a compound semiconductor characterized by diffusing the active impurity into the compound semiconductor substrate (2) A carbide-hydride vapor of the active impurity element to be diffused into the compound semiconductor substrate is heated at a high temperature. 2. The method of diffusing impurities into a compound semiconductor according to claim 1, wherein said compound semiconductor substrate is introduced together with an atmospheric gas containing vapor of a substance that inhibits decomposition.