JPH03279294A - Growth of epitaxial layer - Google Patents

Abstract

PURPOSE:To form an epitaxial film reduced in the contamination of a gas and in the damage caused by sputtering gas ions by using a rare gas element of an atomic number larger than Ar as a gas fed into a sputtering chamber. CONSTITUTION:A desired target 2 having magnets 4 on the back surface thereof and a substrate 3 are disposed in a sputtering chamber 1 in a mutually faced state. A bias electric voltage is applied to the target 2 from a RF source through a matching circuit 5 and also a bias electric voltage is applied to from a direct source 8 through a low pass filter 7. A rare gas element (e.g. Kr) having an atomic number larger than that of Ar is fed from a gas-feeding opening 9 to collide against the target 2, thereby allowing the thin film of the target to epitaxially grow on the substrate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application Field> The present invention relates to a method for growing an epitaxial layer of silicon, molybdenum, etc. by sputtering method.

<Conventional technology> Conventionally, bipolar transistors, BiCMO8, etc.
Silicon wafers are used to fabricate SI. As a method for growing a silicon epitaxial layer on this silicon wafer, for example, there is a high temperature CVD method.

However, in order to cope with the increase in the diameter of silicon wafers and the decrease in epitaxial temperature, a technique has been known in which a silicon epitaxial layer is formed by, for example, the sputtering method described below.

In this method, a silicon substrate is disposed in a sputtering chamber facing silicon, which is a target material, and a bias voltage is applied to the target material. A bias voltage is also applied to the silicon substrate.

Argon was used as the sputtering gas.

Then, by performing high-frequency sputtering, argon ions collide with silicon, which is a target material, and silicon atoms are deposited on the silicon substrate to obtain a thin film.

<Problems to be Solved by the Invention> However, in such conventional sputtering methods, the epitaxial thin film contains argon atoms at a high concentration (1019 cm-3). As a result, a problem has arisen in that the properties of the silicon thin film have deteriorated. For example, the electron mobility in a silicon thin film is significantly lower than that in a bulk crystal.

<Point of focus for problem solving> This is because the lower the pressure of the sputtering gas, the greater the number of argon atoms incorporated into the silicon thin film, so the argon ions incident on the negatively biased target are neutralized. It is thought that the particles recoil in a high-energy state and are incorporated into the silicon thin film. Furthermore, the recoil of these argon atoms damages the silicon thin film.

Therefore, the present inventor proposed that when the mass of the sputtering gas element is larger than that of the target material,
The focus is on the fact that even if the element collides with the target material, the number of recoil sputtering gas atoms decreases.

An object of the present invention is to provide a method for growing an epitaxial layer with less gas contamination and less damage caused by sputtering gas (argon) ions.

<Means for Solving the Problems> The present invention includes a step of disposing a predetermined target material and a substrate facing each other in a sputtering chamber, applying a first bias voltage to the target material, and applying a first bias voltage to the substrate. In a method for growing an epitaxial layer, the method comprises the step of epitaxially growing a thin film on a substrate by applying a bias voltage of 2 and introducing a gas containing an ion-generating element into the sputtering chamber and causing it to collide with a target material. , a method for growing an epitaxial layer in which the ion generating element is selected from rare gas elements having an atomic number higher than that of argon.

<Function> In the epitaxial layer growth method according to the present invention,
A predetermined target material and a substrate are placed facing each other in a sputtering chamber.

A first bias voltage is applied to the target material, while a second bias voltage is applied to the substrate.

At the same time, a gas containing an ion-generating element is introduced into the sputtering chamber to generate ions and cause them to collide with the target material.

In this way, a thin film of the target material is epitaxially grown on the substrate.

In this case, the ion generating element is selected from rare gas elements having an atomic number larger than that of argon. For example, krypton or xenon is used as the sputtering gas.

In this way, when the mass of the sputtering gas element is larger than that of the target material, even if the element collides with the target material, the element itself has kinetic energy and becomes suspended in the sputtering chamber. Not,
The element is not contained in the epitaxial layer on the substrate. Further, the epitaxial layer on the substrate is not damaged.

<Example> Embodiments of the present invention will be described below with reference to the drawings.

As the sputtering apparatus, a magnetron sputtering apparatus having a well-known configuration is used, as shown in FIG. In this figure, in a sputtering chamber 1, for example, silicon 2 as a target and a silicon substrate 3 are disposed facing each other. A magnet 4 is arranged on the back side of the silicon target 2. Further, the silicon target 2 is supplied with a frequency of, for example, 100 MHz via a matching circuit 5.
RF power source 6 is connected. Further, the silicon target 2 is connected to a DC power source 8 via a low-pass filter 7.

The sputtering chamber 1 is configured such that an elemental gas having a mass larger than argon gas, such as krypton gas or xenon gas, can be supplied from a gas supply port 9.

In addition, the interior of this sputtering chamber l is heated to an ultra-high vacuum (about 10-1 Torr) by a turbo pump or the like from the exhaust port 10.
is maintained.

Further, the structure is such that a bias voltage is applied to the silicon substrate 3 as well. In other words, 12 in the figure is the DC power supply, and 13 is the DC power supply.
indicate low-pass filters, respectively. 14 is a capacitor.

In the sputtering apparatus having the above configuration, a silicon target 2 is placed in a sputtering chamber 1, and a predetermined bias voltage is applied thereto. At the same time, a positive bias, for example, is also applied to the silicon substrate 3 disposed opposite the target 2.

From this state, krypton gas, for example, is supplied into the sputtering chamber 1. Plasma is generated by applying a high frequency to the target 2, and krypton gas ions are accelerated to collide with the target 2.

In this way, a target silicon thin film is epitaxially grown on the substrate 3.

As the sputtering gas, in addition to xenon or the like, a mixed gas of a gas that does not react with the target, such as krypton, can also be used.

FIG. 2 shows the rate of incorporation of rare gas elements into the epitaxial layer by discharge gas when the target is molybdenum. As shown in this figure, the mixing rate of krypton gas is significantly reduced compared to argon gas or neon gas. Therefore, it is considered that the mixing rate of xenon gas, which has a larger mass than krypton gas, is further reduced.

<Effects> As explained above, according to the epitaxial layer growth method of the present invention, gas contamination is reduced and
An epitaxial layer that is less damaged by sputtering gas ions can be formed on a substrate.

[Brief explanation of drawings]

FIG. 1 is a conceptual diagram showing a schematic configuration of a sputtering apparatus according to an embodiment of the present invention, and FIG. 2 is a graph showing a rate of sputtering gas mixed into a target according to an embodiment. 1...Sputtering chamber, 2...Silicon target, 3...
...Silicon substrate.

Claims (1)

[Claims] A step of arranging a predetermined target material and a substrate facing each other in a sputtering chamber, and applying a first bias voltage to the target material and a second bias voltage to the substrate. and a step of epitaxially growing a thin film on a substrate by introducing a gas containing an ion-generating element into the sputtering chamber and causing it to collide with a target material. A method for growing an epitaxial layer, characterized in that a rare gas element having an atomic number higher than argon is selected.