JP2003347219A - Vapor growing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, as an area for controlling a flow rate with high precision is narrow in an MFC, gas having a widely different flow rate cannot to controlled with high precision by one set of the MFC, and for this reason in a prior art, another MFC (4) 45 having a different area of the flow rate from an MFC (3) 40 is provided to switch the MFC (3) 40 and the MFC (4) 45 in response to the flow rate, so that a device has been complicated and the cost thereof has been increased. <P>SOLUTION: A pulse valve 20 is connected in series with the MFC 21, and passing gas is not mode continuous but in a pulse-like manner. If the duty ratio of the pulse valve 20 is set to, for example, 1/10, the flow rate is decreased to substantially 1/10, and if 1/100, it drops to substantially 1/100. One set of the MFC can be substituted for three sets of the MFC and a device structure is simplified to lower the cost. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vapor phase epitaxy apparatus, and more particularly to an organometallic vapor phase epitaxy apparatus used for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional metal organic chemical vapor deposition (MOV).
2 is a system diagram of a (PE) device 30. FIG. The carrier gas of hydrogen gas or nitrogen gas is divided into three systems after leaving the gas cylinder 31.

The carrier gas passing through the first system 32 reaches a reaction tank 35 through a pressure control valve 34 while the flow rate is controlled by a mass flow controller (MFC) (1) 33.

The carrier gas of the second system 36 is MFC
(2) While controlling the flow rate at 37, the liquid enters the tank of the source (1) 38, bubbling and evaporating the liquid of the source (1) 38, and contains the vapor of the source (1) 38 and passes through the pressure control valve 34. The reaction tank 35 is reached. The liquid of the source (1) 38 is an organic metal, for example, trimethylindium (TMI).

The carrier gas of the third system 39 is MFC
(3) While the flow rate is controlled at 40, the liquid enters the source (2) 41 tank, bubbling and evaporating the liquid of the source (2) 41, and contains the vapor of the source (2) 41 and passes through the pressure control valve 34. The reaction tank 35 is reached. The liquid of the source (2) 41 is also an organic metal, for example, diethyl zinc (DEZ).
n).

The pressure inside the reaction tank 35 is reduced by a vacuum pump 42. A susceptor 43 is provided in the reaction tank 35, and a semiconductor wafer 44 is mounted thereon. Since the susceptor 43 has a built-in heater, the semiconductor wafer 44 can be heated to a predetermined temperature.

A carrier gas containing vapor of organometallic molecules of the source (1) 38 and / or the source (2) 41 is blown to the semiconductor wafer 44. The organometallic molecules that collide with the semiconductor wafer 44
Is rapidly decomposed because the temperature is high, and the remaining metal atoms grow epitaxially on the surface of the semiconductor wafer 44. Source (1) 38 is the main metal, Source (2) 41
Is an impurity metal, an epitaxial layer containing an impurity can be formed.

[0008]

For example, the impurity concentration of the InGaAs light absorption layer, the n-InP window layer, etc. of the light-receiving diode is low and is of the order of 10E16 / cm3 (10En represents 10 to the nth power). Therefore, at this time, if the source (2) 41 is an impurity, the flow rate of the carrier gas flowing through the MFC (3) 40 of the source (2) 41 is about 3 cc / min.

On the other hand, for example, the impurity concentration of the InP buffer layer of the laser diode is two orders of magnitude higher than that of the InP buffer layer.
It is on the order of E18 / cm3. Therefore, at this time, if the source (2) 41 is an impurity, the flow rate of the carrier gas flowing through the MFC (3) 40 of the source (2) 41 is 30 c
c / min.

Since the MFC has a narrow range in which the flow rate can be accurately controlled, it is impossible to control both of the above-mentioned examples with one MFC. Therefore, conventionally, another MFC (4) 45 having a different flow rate region from the MFC (3) 40 is provided and the MFC (4) 45 is provided.
(3) The 40 and the MFC (4) 45 are switched according to the flow rate. As a result, the apparatus becomes complicated and the cost increases.

An object of the present invention is to precisely control gases of different flow rates by a single MFC.

[0012]

Conventionally, gas passing through the MFC has been continuous. However, in the present invention, the gas passing through the MFC is controlled in a pulsed manner. This is realized by inserting a valve that opens and closes in a pulsed manner in series with the MFC, and automatically controls the opening and closing of the valve. If the ratio (duty ratio) of the valve opening time is, for example, 1/10, the flow rate is substantially 1/10, and if it is 1/100, the flow rate is substantially 1/100.

In this case, the impurities are supplied intermittently. However, during the growth, the impurity atoms are diffused even in the solid, so that the distribution of the impurity atoms does not become uneven. That is, the distribution of impurity atoms becomes uniform as in the conventional case.

The duty ratio can be freely selected. For example, if there are three types, ie, 1, 1/10, and 1/100, 1
Three MFCs can take the place of three MFCs.
In this way, the apparatus is simplified and costs are reduced.

According to the first aspect of the present invention, a liquid source of an organic metal is bubbled and evaporated by a carrier gas whose flow rate is controlled by a mass flow controller, and a vapor of the organic metal is placed on the carrier gas and sprayed onto a heated semiconductor wafer. An organometallic vapor phase epitaxy apparatus for epitaxially growing metal atoms obtained by decomposing an organic metal on a semiconductor wafer surface, wherein a carrier gas is intermittently flown.

According to a second aspect of the present invention, in the metal organic chemical vapor deposition apparatus according to the first aspect, a valve for automatically opening and closing intermittently is connected in series to the mass flow controller in order to intermittently flow the carrier gas. Metal organic chemical vapor deposition apparatus.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a metal organic chemical vapor deposition (MO) of the present invention.
FIG. 11 is a system diagram of an example 10 of a (VPE) device. The carrier gas of hydrogen gas or nitrogen gas is divided into three systems after leaving the gas cylinder 11.

The carrier gas passing through the first system 12 reaches the reaction tank 15 through the pressure control valve 14 while the flow rate is controlled by the mass flow controller (MFC) (1) 13.

The carrier gas of the second system 16 is MFC
(2) While controlling the flow rate at 17, enter the tank of the source (1) 18 and bubbling the liquid source (1) 18;
The mixture is evaporated and contains the vapor of the source (1) 18 and reaches the reaction tank 15 through the pressure control valve 14. The liquid of the source (1) 18 is an organic metal, for example, trimethylindium (TMI).

The carrier gas of the third system 19 enters the tank of the source (2) 22 while the duty ratio of the passage time is first controlled by the pulse valve 20 and the flow rate at the time of passage is controlled by the MFC (3) 21. , Source (2) 22
Is bubbled and evaporated, and contains the vapor of the source (2) 22 and reaches the reaction tank 15 through the pressure control valve 14.

The duty ratio of the pulse valve 20 is, for example, 1/10 or 1 /
100 can be freely set and the set value is automatically maintained and controlled.

In the figure, the pulse valve 20 is an MFC (3) 2
1, but may be between the MFC (3) 21 and the source (2) 22.

The liquid of the source (2) 22 is also an organic metal, for example, diethyl zinc (DEZn).

The pressure inside the reaction tank 15 is reduced by a vacuum pump 24. The reaction tank 15 has a susceptor 25 on which a semiconductor wafer 26 is mounted. The susceptor 25 has a built-in heater and can heat the semiconductor wafer 26 to a predetermined temperature.

The carrier gas containing the vapor of the organometallic molecules of the source (1) 18 and / or the source (2) 22 is blown onto the semiconductor wafer 26. The organometallic molecules that collided with the semiconductor wafer 26
Is heated to a high temperature, so that it is quickly decomposed, and the remaining metal atoms grow epitaxially on the surface of the semiconductor wafer 26. Source (1) 18 is the main metal, Source (2) 22
Is an impurity metal, an epitaxial layer containing an impurity can be formed.

[0026]

According to the present invention, the gas passing through the MFC is pulsed, not continuous. For this purpose, a valve that opens and closes in a pulsed manner is inserted in series with the MFC, and the opening and closing of the valve is automatically controlled to be realized. The valve opening time ratio (duty ratio) can be freely set. For example, if the ratio is 1/10, the flow rate is substantially 1/10, and if it is 1/100, the flow rate is substantially 1/100.

In this case, the impurities are intermittently supplied, but during the growth, the impurity atoms are diffused even in the solid, so that the distribution of the impurity atoms becomes uniform as in the conventional case.

The duty ratio can be freely selected. For example, if there are three types, ie, 1, 1/10, and 1/100, 1
Three MFCs can take the place of three MFCs.
Therefore, the device configuration is simplified and the cost is reduced.

[Brief description of the drawings]

FIG. 1 is a system diagram of an example of a metal organic chemical vapor deposition (MOVPE) apparatus of the present invention.

FIG. 2 is a system diagram of a conventional metal organic chemical vapor deposition (MOVPE) apparatus.

[Explanation of symbols]

10. Organometallic vapor phase epitaxy apparatus of the present invention 11 Gas cylinder 12 First system 13 MFC (1) 14 Pressure control valve 15 Reaction tank 16 Second system 17 MFC (2) 18 sources (1) 19 Third system 20 pulse valve 21 MFC (3) 22 sources (2) 23 Valve Controller 24 vacuum pump 25 Susceptor 26 Semiconductor wafer 30 Conventional Metalorganic Vapor Phase Epitaxy System 31 Gas cylinder 32 1st system 33 MFC (1) 34 Pressure control valve 35 Reaction tank 36 Second system 37 MFC (2) 38 sauces (1) 39 Third system 40 MFC (3) 41 Source (2) 42 vacuum pump 43 Susceptor 44 Semiconductor wafer 45 MFC (4)

Claims (2)

[Claims] An organic metal liquid source is bubbled and evaporated by a carrier gas whose flow rate is controlled by a mass flow controller, and the organic metal vapor is placed on the carrier gas and sprayed on a heated semiconductor wafer.
A metal organic chemical vapor deposition apparatus for intermittently flowing the carrier gas in a metal organic chemical vapor deposition apparatus for epitaxially growing metal atoms decomposed of the organic metal on the surface of the semiconductor wafer. 2. The organic metal vapor phase epitaxy apparatus according to claim 1, wherein an intermittent automatic opening / closing valve is connected in series to said mass flow controller for intermittently flowing said carrier gas. Metallic vapor phase epitaxy.