JPS6122621A - Vapor-phase growing method - Google Patents

Abstract

PURPOSE:To stabilize the flow of reactive gas on the surface of a substrate as well as to make uniform the thickness and quality of film by a method wherein a semiconductor substrate is placed in a reaction chamber, and a smoothing plate is provided in the forward direction of the semiconductor substrate. CONSTITUTION:A reaction chamber 1 is made of quartz and the like, and it is placed horizontally. A substrate holder 3 is provided in the reaction chamber 1. A mounting plate 4 is provided at the tip of the substrate holder 3. A semiconductor substrate 2 is obliquely placed on the mounting plate 4. A rectifying plate 6 is provided in the lower forward direction of the semiconductor substrate 2. The smoothing plat 6 has a wing type cross-section. A reaction gas stream 5 flows into the reaction chamber 1 from one side of the chamber. The gas stream 5 passing above the smoothing plate 6 flows in parallel with the surface of the substrate 2. The gas stream 5 passing below the smoothing plate 6 approaches the substrate 2. As a result, the gas stream 5 becomes the stream of a laminar flow. The gas stream is stabilized, and the thickness and the quality of the film is made uniform.

Description

DETAILED DESCRIPTION OF THE INVENTION (A) Technical Field The present invention relates to semiconductor growth and improvement of a vapor phase growth method without processing.

To form an epitaxial layer on a semiconductor wafer, vapor phase epitaxy, liquid phase epitaxy, molecular beam epitaxy, etc. are used.

Vapor phase epitaxy has a long history among semiconductor epitaxy technologies and is widely used practically for silicon phenol.

To epitaxially grow silicon and dopants on a silicon phenol, 5iC4 and H2 gases, such as nitrogen as a carrier gas, are pumped into the reaction vessel and passed over the top of the silicon phenol. The silicon cube is heated, and reduced silicon and dopants are epitaxially grown 17 thereon.

The silicon cube is placed on a susceptor made of carbon or the like, and the susceptor is heated by a high frequency coil.

Similar vapor phase epitaxy technology has been established for aAs wafers.

To fabricate various devices on semiconductor wafers,
In addition to epitaxy, processes such as, for example, thermal oxidation are carried out.

Thermal oxidation is a process that creates an oxide layer on silicon.

A large number of silicon cubes are placed in a volume t%, placed in an electric furnace and heated, and 02N2 is passed into the container to supply oxygen to the heated silicon surface, thereby removing silicon from the surface. It oxidizes.

In addition, on the silicon cube, an siN insulating film, 5iQ
When forming the insulating film 2, chemical vapor deposition method (CV
D method) is used.

To make a SiN film, place it on top of a heated silicon cube.
A gas flow consisting of SiH4, NH8, and N2 is passed to deposit a SiN film on the silicon surface.

To form the 5i02 film, a gas consisting of SiH4,02 and N2 is flowed onto the heated silicon cube to deposit a 5i02 film on the surface of the silicon.

Furthermore, the CVD method is also used to diffuse P-type or n-type impurities into the silicon cube to create a p-n junction.

Using nitrogen gas as a carrier gas, B2H6, NHl
1 and passed as a gas stream over the silicon cueva. Then, a BN film is formed on the silicon cube, and B diffuses into the silicon cube from this film to form a p-type head region.

In this way, vapor-phase eclipse (
yapor phase epitaxy, VPE)
, thermal oxidation, formation of an insulating film by the CVD method, impurity diffusion, etc. are performed using gas phase reactions.

In the present invention, these processes will be combined and referred to as a vapor phase growth method.

Among these, only vapor phase Equixy VPE is the most suitable name for vapor phase growth because it is the growth of a single crystal.

However, the problem with the prior art that the present invention addresses is that the VP
In addition to E, it always appears when some kind of processing is performed on Kuehka using a gas phase reaction.

Therefore, formation of siN, 5iQ2 film by CVD method,
Diffusion of impurities by CVD method, oxidation, etc. will be included in the category of vapor phase growth method.

(a) Prior art and its problems The structure of the vapor phase growth method is as follows: (1) A semiconductor cube is placed on a susceptor and housed in a reaction vessel.

(2) There is a high frequency heating coil or a resistance heater around the reaction vessel to heat the susceptor and wafer.

(3) The reaction vessel is placed horizontally, and the reaction gas flows through it in a substantially horizontal direction.

(4) The reactive gas is a mixture of an inert carrier gas such as nitrogen and a component gas that chemically reacts with the wafer such as silicon or GaAS.

(5) At least two types of gas flow simultaneously. Each gas flow rate is measured and monitored.

Further, the total amount of gas flowing through the reaction container can be freely adjusted by a flow rate adjustment valve on the gas supply side or an exhaust adjustment valve provided on the opposite side of the reaction container.

Each of the reaction gases has a regulating valve, so the flow rate can be adjusted independently.

The temperature of the wafer can be arbitrarily controlled by adjusting the power of the heater or the high-frequency coil.

The reason why the reaction container is horizontal is because it allows many wafers to be grown side by side at the same time.

The wafer is supported either horizontally or slightly oblique to the flow.

If supported horizontally, the gas flow will be parallel to the square surface. This is often the case. However, if the flow rate is not sufficient, the film may be thicker on the upstream side where the reactive gas hits the wafer first, and thinner on the downstream side. The film thickness becomes non-uniform in the direction along the flow. Also, the film quality is very uniform.

Therefore, the wafer surface is sometimes tilted so that the front side is slightly downward.

FIG. 2 is a cross-sectional view showing an example of a wafer in a forward-inclined arrangement.

A semiconductor substrate (wafer) 2 is supported in a reaction vessel 1 by a substrate holder 3. At the front end of the board holder 3,
A base plate 4 that is slightly tilted forward is attached, and a semiconductor substrate 2 is placed on this base plate 4.

Reactant gas stream 5 flows approximately horizontally within reaction vessel 1 .

The flow hits and passes the forward-tilting substrate 2.

A chemical reaction occurs between the substrate 2 and a portion of the reaction gas.

This figure shows only one quefer, but in reality, many quefers are accommodated in some reaction vessels 1 and undergo a chemical reaction.

In this example, since the base plate 4 and the semiconductor substrate 2 are tilted forward,
The rear part of the substrate 2 is also hit by the gas and reacts there. In this way, the front and back layers are designed to have approximately the same thickness.

However, in reality, the gas flow is turbulent at the rear end and front end of the substrate 2. Even if the gas flow is originally a laminar flow, the presence of the base plate 4 and the substrate 2 causes it to be significantly disturbed.

Since the flow is turbulent, the thickness of the film formed on the substrate is non-uniform, and the quality of the film is different.

(1) Method of the present invention The present invention prevents the reaction gas flow from being disturbed in the vicinity of the substrate;
The purpose is to make the thickness and quality of the vapor-grown film uniform.

FIG. 1 is a sectional view for explaining the vapor phase growth method of the present invention.

The reaction container 1 is a container such as a quartz tube, and is used horizontally. The semiconductor substrate 2 is placed obliquely on the second side of the base plate 4 at the tip of the substrate holder 3.

A reactant gas stream 5 enters the reaction vessel 1 at one end and passes through the other end. The reaction gas varies depending on the purpose, but it consists of a component that undergoes a chemical reaction and a carrier gas for transporting the component.

The above configuration is no different from the conventional one.

In the present invention, a new rectifying plate 6 is provided in front of the lower part of the substrate 2.

The current plate 6 allows the reaction gas flow 5 to flow through the substrate holder 3 .

This prevents it from being disturbed by hitting the base plate 4 at the front end.

The current plate 6 has a cross section shaped like an airplane airfoil.

The flow direction of the gas flow passing above the rectifier plate 6 is changed upward by the rectifier plate 6, and becomes substantially parallel to the surface of the substrate 2.

The gas flow passing under the current plate 6 advances along the lower surface of the current plate with an airfoil-shaped cross section, and approaches the substrate 2 as a diagonally upward flow.

Since the flow is obliquely upward, the flow is almost parallel to the substrate 2. Therefore, when the flow contacts the substrate 2,
The direction of the flow is equal to the orientation of the substrate, resulting in a laminar flow.

The reaction gas flow hitting the lower end of the base plate 4 is disturbed by the collision, but since these gases circulate below the base plate 4, even if the flow becomes turbulent, it will have an adverse effect on the vapor phase growth on the substrate 2. It affects me a lot.

As a result, the flow of the reactant gas passing through the region A between the baffle plate 5 and the base plate 4 becomes stable. Since this is just before board 2, area M
It is important that the gas flow is stable at A.

In addition, there are 5 rectifying plates, which are rotatable and can be moved up and down.
It is able to move laterally. This makes it possible to set the optimum angle and position of the rectifying plate 5 depending on the type, pressure, and flow rate of the reaction gas.

(1) Effects (1) When performing crystal growth, insulating film formation, etc. on a semiconductor wafer by vapor phase growth, according to the present invention, the flow of the reactant gas on the substrate surface is stabilized.

It has the advantage of growing uniformly in film thickness and quality.

(2) Gas flow can be easily changed by finely adjusting the current plate. In other words, the number of variables that can be controlled increases, making it easier to set conditions.

[Brief explanation of the drawing]

FIG. 1 is a sectional view for explaining the structure of the vapor phase growth method of the present invention. FIG. 2 is a cross-sectional view of an example of a conventional vapor phase growth apparatus, showing a state in which a substrate is placed tilted forward in a reaction gas. 1.--Reaction container 2 ・Semiconductor substrate 3 ・Substrate holder 4 ..Base Plate 5 ---Reaction gas flow 6... ・Rectifier plate

Claims (2)

[Claims] (1) A semiconductor substrate 2 is supported by a substrate holder 3 in a reaction vessel 1, and a desired film is formed on the semiconductor substrate 2 by heating the reaction vessel 1 and flowing a reaction gas flow 5. A vapor phase growth method characterized in that a rectifying plate 6 that can be rotated, vertically and horizontally displaced is provided in front of the semiconductor substrate 2 with respect to the flow of the reactant gas flow 5. (2) The current plate 6 has an airfoil-shaped cross section.
1) The vapor phase growth method described in section 1).