JPH02230719A - Thin-film growing and machining apparatus - Google Patents

Abstract

PURPOSE:To eliminate mutual contamination of raw materials and to facilitate the formation of the different kinds of thin film crystals by connecting a main vacuum chamber wherein a thin film is grown or machined on a substrate to gas feeding devices which feed a raw material gas or an etching gas through gate valves. CONSTITUTION:In vacuum chambers 1 and 2, crucibles comprising boron nitride which are gas feeding devices and molecular beam cells 3a and 3b comprising heaters made of tantalum are provided, respectively. The vacuum chambers 1 and 2 are connected to the main vacuum chamber 7 wherein a substrate 5 is provided through gate valves 6a and 6b. A raw material gas which is supplied from one vacuum chamber 1 performs the specified thin-film growing or machining on the substrate 5 in the main vacuum chamber 7. Thereafter, the gate valve 6a is closed, and the gas is completely exhausted from the inside of the main vacuum chamber 7. Another etching gas is fed into the main vacuum chamber 7 from the other vacuum chamber 2 through the gate valve 6b. Therefore, the thin-film growing and machining can be performed on the substrate in the state where the gas does not remain without moving the substrate in the main vacuum chamber.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an apparatus for growing and processing thin films, and more particularly to an apparatus for growing and processing semiconductor thin films using ultra-high vacuum.

[Prior Art] Conventionally, thin film growth is an extremely important step in manufacturing semiconductor devices having fine structures such as high-density integrated circuits, semiconductor lasers, and photodetecting elements.

} Vapor phase growth, liquid phase growth, and molecular beam epitaxial methods are used to grow W films. Of these, the molecular beam epitaxial method involves direct vapor deposition from raw materials onto a crystal substrate in an ultra-high vacuum. Advantageously, thin films of high purity can be obtained and the controllability is also the best.

In the molecular beam epitaxial method, each raw material is placed in a crucible made of boron nitride or the like, heated and evaporated. The crystal substrate is placed facing a crucible containing a raw material, and is heated so that the evaporated raw material molecules reach the crystal substrate and undergo epitaxial growth. Particularly in the molecular beam epitaxial method for compound semiconductors using group (I) and group V solid raw materials, the supply of the raw materials is controlled by opening and closing a shutter disposed in front of the raw materials.

Using a molecular beam epitaxial device, e.g. substrate temperature 6
When growing gallium arsenide at 00° C., the adhesion coefficient of arsenic on the substrate is less than 1, so the thickness of the grown film is controlled by the amount of gallium supplied. At this time, arsenic is supplied in excess, and the vapor pressure becomes high, so that the degree of vacuum becomes approximately 1×1 8 Torr due to the arsenic vapor.

[Problems to be Solved by the Invention] From the above, when a material with a high vapor pressure such as arsenic is used, the raw material remains in the vacuum chamber as an atmosphere after growth, and in this state, different crystals form in the vacuum chamber. When growth is performed, it will be affected by residual gas.

For example, when germanium is subsequently formed after gallium arsenide crystal growth, arsenic remaining in the vacuum chamber is incorporated into germanium, forming a crystal with n-type conductivity. Therefore, there is a problem in that it is not possible to form highly purified germanium or p-type conductive germanium with good reproducibility.

One possible way to solve this problem is to combine the two vacuum chambers in separate vacuum chambers and prepare different materials for each vacuum chamber. For example, there is a method in which potassium arsenide is formed in one vacuum chamber, and then the substrate temperature is sufficiently lowered and transferred to the other vacuum chamber, where germanium is formed.

However, with this method, it is necessary to transport the substrate between vacuum chambers depending on the type of epitaxial layer to be grown.
At that time, the temperature of the substrate had to be lowered each time it was transported, which caused a problem in that the series of operations became complicated and took a long time.

The purpose of the present invention is to form two types of thin films without mutually contaminating each other, without the need for substrate illumination and transport, without changing the substrate temperature, or to enable two types of processes without mutual substance contamination. The purpose of the present invention is to provide thin film forming and processing equipment.

[Means for Solving the Problems] The present invention provides a main vacuum chamber for growing or processing a thin film on a substrate, a plurality of vacuum chambers connected to the main vacuum chamber via gate valves, and a plurality of vacuum chambers connected to the main vacuum chamber through gate valves. and a gas supply device attached to each of the main vacuum chambers for supplying raw material gas or etching gas, and the raw material waste or etching gas is supplied to the substrate in the main vacuum chamber through the gate valve. This is a thin film growth/processing device.

[Operation] In the apparatus according to the present invention, a plurality of vacuum chambers are connected to a main vacuum chamber equipped with a substrate via a gate valve, and raw materials can be supplied from the gas supply devices of both vacuum chambers without moving the substrate. .

After the source gas or etching gas supplied from one vacuum chamber performs a predetermined thin film growth or processing on the substrate in the main vacuum chamber, the gate valve is closed and the gas is completely exhausted from the main vacuum chamber. Another source gas or etching gas is supplied from a waste supply device in another vacuum chamber.
It is supplied to the substrate in the main vacuum chamber via a gate valve.

Therefore, the substrate inside the main vacuum chamber does not need to be moved.
Thin film growth and processing can be performed without residual gas.

[Embodiments] Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic diagram of an embodiment of the present invention.

The vacuum chambers 1 and 2 are equipped with molecular beam cells 3a and 3b each consisting of a boron nitride crucible and a tantalum heater, and liquid nitrogen shrouds 4a,
4b is installed, and the vacuum chambers 1 and 2 are connected to gate valves 6a and 6.
It is connected via b to a main vacuum chamber 7 in which a substrate 5 is installed. For example, the molecular beam cell 3a of the vacuum chamber 1 stores gallium, arsenic, which are materials for group II and group V compound semiconductors, and silicon and beryllium, which are dopants. It contains germanium and gallium, which is a p-type dopant of germanium.

In this embodiment, a case will be described in which the above-mentioned apparatus is used to fabricate a heteroepitaxial layer structure in which gallium arsenide 9 and germanium 10 are formed on a gallium arsenide substrate 8, as shown in FIG.

The film thickness of gallium arsenide 9 is 5000 cm, the doping is n-type 5 x 1017 cm-3, and the film thickness of germanium is 200 cm.
0 person, doping is p-type 1×1019 cm−3. This structure corresponds to the collector and base layers of a heterojunction bipolar transistor using gallium arsenide and germanium, and p-type germanium must be reproducibly formed in this state.

First, the substrate 5 in the main vacuum chamber 7 is heated to 450°C, and gallium and arsenic are doped by heating and evaporated from the molecular beam cell 3a of the vacuum chamber 1, and gallium is grown at a growth rate of 1 micron per hour. Arsenic 9 is formed. Next, the shutter of the cell is closed, and after the growth is completed, the gate valve 6a is closed, and the
Leave it for 0 minutes to reduce the residual arsenic level to 10' Torr or less. After that, open the gate valve 6b to vacuum 2, and
Lower the temperature to 350°C, open the shutter of the germanium and gallium molecular beam cell 3b in the vacuum chamber 2, and
Type germanium is formed. The level of germanium formed in this way is 1 x 1o19cm.
' could be formed with good reproducibility.

On the other hand, if germanium is housed in the same vacuum chamber as gallium and arsenic to form germanium, the residual partial pressure of arsenic will incorporate arsenic as an n-type impurity, and its doping level will depend on its residual partial pressure, so gallium When doping, the reproducibility of p-type semiconductor formation of 1×10 19 cm −2 was poor compared to the present invention.

Although this example describes the case of forming two types of semiconductors, this apparatus can be used for various combinations, such as when performing thin film growth and etching, or when roughly forming an insulating film and a semiconductor. It is possible to use

[Effects of the Invention] As explained above, by using the thin film growth/processing apparatus of the present invention, there is no cross-contamination of raw materials unlike in the past.
Furthermore, different types of thin film crystals can be formed or processed successfully without the need to transport the growth substrate or to raise or lower the temperature of the substrate.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram of an embodiment of the present invention, and FIG. 2 is a partial cross-sectional view of a crystal made of gallium arsenide and germanium produced by the thin film growth/processing apparatus of the present invention. 1, 2... Vacuum chamber 3a, 3b... Molecular beam cell 4a, 4b... Liquid nitrogen shroud 5... Substrate 6a, 6b... Gate valve 7...
Main vacuum chamber 8...Gallium arsenide substrate 9...Gallium arsenide 10...Germanium

Claims (1)

[Claims] (1) A main vacuum chamber for growing or processing a thin film on a substrate, a plurality of vacuum chambers connected to the main vacuum chamber via gate valves, and a source gas or 1. A thin film growth/processing apparatus comprising a gas supply device for supplying an etching gas, the source gas or the etching gas being supplied to the substrate in the main vacuum chamber via the gate valve.