JP2002334840A - Method of manufacturing wafer to be subjected to reactive gas treatment, and method and apparatus for performing reactive gas treatment on wafer manufactured using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method of manufacturing wafer subjected to reactive gas treatment, and to provide a method and apparatus for performing reactive gas treatment by which the occurrence of moisture can be suppressed at the time of performing reactive gas treatment, such as epitaxial growth, etc., on a wafer manufactured by the manufacturing method. SOLUTION: Using the method of manufacturing wafer, a silicon wafer W, to be subjected to reactive gas treatment which is performed by causing a reaction between the surface of the wafer and a reactive gas, is manufactured; and the method includes a step of forming a silicon oxide film 10 on the rear surface of the wafer W by the CVD method, and a step of modifying the film 10 by heat-treating the wafer W at a temperature between 700 deg.C and 1,000 deg.C, after the film 10 has been formed in the preceding step.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a reactive gas processing wafer for performing a reactive gas treatment such as epitaxial growth on a surface using a reactive gas, and a reactive gas for a wafer using the same. The present invention relates to a processing method and a reactive gas processing device.

[0002]

2. Description of the Related Art In recent years, as a silicon wafer for MOS devices, an epitaxial wafer obtained by vapor-phase growing a single-crystal silicon thin film (epitaxial layer) at a predetermined impurity concentration on a silicon wafer having an extremely low resistivity has been developed. Manufactured with growth equipment. In this apparatus, a silicon wafer is placed in a chamber, a reactive gas is flowed, and epitaxial growth is performed on the wafer. Also, in the process of manufacturing a semiconductor such as an LSI,
Various CVD (Chemical Vapor Deposition) apparatuses for forming a thin film on a wafer using a reactive gas have been used.

[0003] Wafers epitaxially grown on the above-mentioned low-resistance wafers have features such as improvement of gettering ability, reduction of latch-up, and reduction of soft errors. In order to prevent auto-doping (doping by impurities detached from the back surface), a low-resistance wafer having a silicon oxide film formed on the back surface is used for the wafer. Normally, as a silicon oxide film formed on the back surface, a C film having a high growth rate is used.
LTO (Low Temperature Oxid) deposited by VD method
e) is used.

[0004]

The above-mentioned conventional reactive gas processing techniques such as epitaxial growth have the following problems. In other words, in epitaxial growth and the like, a corrosive gas such as ultra-high purity hydrogen chloride gas or ammonia gas is used as a reactive gas. Since the metal (heavy metal) generated from the metal part causes contamination and is harmful, it is necessary to reduce the moisture in the chamber as much as possible. However, even if the moisture contained in the reactive gas itself and the moisture brought in when the wafer is carried in are reduced as much as possible, moisture still desorbs from the wafer itself and increases the amount of moisture in the chamber. Reduction is required.

The present invention has been made in view of the above-mentioned problems, and a method of manufacturing a reactive gas processing wafer in which generation of moisture is suppressed during a reactive gas processing such as epitaxial growth, and a method of manufacturing a wafer using the same. It is an object of the present invention to provide a reactive gas processing method and a reactive gas processing device.

[0006]

Means for Solving the Problems The present inventors have studied the factors that increase the water concentration in the reaction chamber and found that the water contained in the LTO formed on the back surface of the silicon wafer has
It was found that desorption occurred during the temperature raising step in the chamber. That is, when a thermal oxide film is formed on the back surface, no generation of moisture is observed, whereas LT by the CVD method is performed.
In O, since moisture is generated, it was found that the difference was due to the difference in the film quality of the silicon oxide film depending on the film formation method. As a result of observing the IR spectrum of the LTO and the thermal oxide film, no absorption due to moisture or hydrogen in the film was found in the thermal oxide film, but these large absorptions were seen in the LTO. This is considered to be because the LTO was formed at a relatively low temperature by the CVD method, and thus the film contained moisture. As described above, if the thermal oxide film is formed on the back surface, the generation of moisture can be suppressed, but the growth rate is low. Therefore, it is desired to use LTO having a high growth rate.

Therefore, the present invention has adopted the following constitution based on the above findings in order to solve the above-mentioned problems.
That is, the method for producing a reactive gas processing wafer of the present invention is a method for producing a silicon wafer for performing a reactive gas treatment by reacting a surface with a reactive gas,
A step of forming a silicon oxide film on the back surface of the silicon wafer by a CVD method; and a step of modifying the silicon oxide film by heat-treating the silicon wafer at a temperature of 700 ° C. to 1000 ° C. after the step. It is characterized by the following. Further, the reactive gas processing method of the wafer of the present invention,
A reactive gas processing method for a wafer that reacts a reactive gas with the surface of a silicon wafer, wherein the silicon wafer is manufactured by the method for manufacturing a reactive gas processing wafer of the present invention. Features.

In these reactive gas processing wafer manufacturing methods and wafer reactive gas processing methods, a silicon wafer is heat-treated at 700 ° C. to 1000 ° C. to modify a silicon oxide film. And CVD
All the water contained in the silicon oxide film formed by the method is desorbed and reformed to a film quality that does not reabsorb water,
Water is not desorbed even in the temperature raising step during the reactive gas treatment.

The reactive gas processing apparatus of the present invention has a C
An apparatus for installing a silicon wafer on which a silicon oxide film is formed by a VD method in a reaction chamber and reacting a reactive gas flowing into the reaction chamber with a surface of the silicon wafer to perform a reactive gas treatment. A heat treatment chamber for heat-treating the silicon wafer between 700 ° C. and 1000 ° C. before transporting the silicon wafer into the chamber is provided separately from the reaction chamber.

In this reactive gas processing apparatus, a heat treatment chamber for heat-treating the silicon wafer between 700 ° C. and 1000 ° C. before transferring the silicon wafer into the reaction chamber is provided separately from the reaction chamber. The moisture contained in the silicon oxide film on the back surface can be removed in advance in the heat treatment chamber and the film itself can be modified, so that the removal of moisture from the wafer during the processing in the reaction chamber can be prevented.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment according to the present invention will be described below with reference to FIGS. In these figures, reference numeral 1 denotes a process chamber, 2 denotes a transfer chamber, 3 denotes a load lock chamber, 4 denotes a load lock chamber, and 5 denotes a process moisture meter.

FIG. 1 shows a single-wafer type epitaxial crystal growth apparatus for carrying out a method of manufacturing an epitaxial growth wafer (reactive gas processing wafer) and a wafer epitaxial growth method (reactive gas processing method) according to the present invention. 2 shows a (reactive gas processing device). The epitaxial crystal growth apparatus includes three process chambers (reaction chambers) 1 made of quartz, each of which is a hollow airtight container in which a silicon wafer W is disposed, and a silicon wafer W is loaded into the process chamber 1. A transfer chamber 2 for replacing the atmosphere in an enclosed space, a bake chamber (heat treatment chamber) BC for performing a heat treatment on the silicon wafer W before transfer to the transfer chamber 2, and a process for the bake chamber BC Loading load lock chamber 3 for transporting the previous silicon wafer W and transport chamber 2
And an unloading load lock chamber 4 for unloading the processed silicon wafer W from the substrate.

In each of the process chambers 1, a process moisture meter 5 for sampling the gas introduced into the process chamber 1 and measuring the moisture contained in the gas, and a pressure gauge for measuring the pressure in the process chamber 1 are provided. 7 are provided. A transfer moisture meter 6 for measuring the moisture in the internal atmosphere is also provided in the transfer chamber 2. As the process moisture meter 5 and the transport moisture meter 6, for example, a laser moisture meter having high accuracy and high response speed is desirable.

The laser moisture meter is used as a means for measuring the moisture concentration in a corrosive gas, for example, as disclosed in Japanese Patent Application Laid-Open No.
In this publication, a laser beam is made incident on a tubular cell body connected to a process chamber, and the absorption spectrum of the transmitted laser beam is measured. This laser moisture meter is
Since it can be measured in a non-contact manner with a gas, even a reactive gas can be measured with high accuracy. Thus, the moisture concentration in the process chamber can be measured even during the process. Note that the transport moisture meter 6 is preferably the above-described laser moisture meter, but other than using a capacitance moisture meter or a mass spectrometry method in which moisture is adsorbed on an alumina capacitor or the like to measure a change in its electric capacity. It may be a moisture meter or the like.

The process chamber 1 is connected to a gas supply source (not shown) such as a reactive gas, and the gases (SiCl ₂ H ₂ , SiCl ₃ H, HCl, H ₂ , N ₂ ) from the gas supply source are connected to the process chamber 1.
₂ , B ₂ H ₆ , PH ₃ , SiH _4, etc.), and after being connected to an exhaust gas treatment facility (not shown) via a gas exhaust system and subjected to a reaction in the process chamber 1 The reactive gas and the like can be exhausted to an exhaust gas treatment facility.

The baking chamber BC has a lamp heating type heating mechanism (not shown) for heat-treating the silicon wafer W disposed therein at a temperature between 700 ° C. and 1000 ° C. The heat treatment temperature and the predetermined heat treatment time can be arbitrarily set. In addition,
Considering the throughput, the heat treatment time is preferably in the range of about 1 to 10 minutes.

Next, in this embodiment, as shown in FIG. 2A, an LTO film (silicon oxide film) 10 is formed on the back surface by a normal pressure CVD method at a temperature of about 450 ° C. A case where the silicon film 12 is epitaxially grown on the surface of the silicon wafer W using the above-described epitaxial crystal growth apparatus will be described.

First, the silicon wafer W is loaded from the loading load lock chamber 3 into the baking chamber BC, and the atmosphere in the baking chamber BC is replaced with an inert gas such as N ₂ , and the temperature is set between 700 ° C. and 1000 ° C. Is performed at a predetermined temperature and a predetermined time. At this time, the moisture contained in the LTO film 10 formed by the CVD method is reformed into the modified LTO film 11 which is desorbed and does not reabsorb moisture as shown in FIG. You.

The reason why the heat treatment temperature is limited to the above range is that if the temperature is lower than 700 ° C., the LTO film 10 is not sufficiently desorbed from water and is not sufficiently reformed into a film that does not reabsorb water. If the temperature is set higher than 1000 ° C., inconveniences such as removal of dopants inside the wafer become remarkable. In this embodiment, the heat treatment condition is set at 800 ° C. for 7 to 8 minutes at which a sufficient effect can be obtained.

After the completion of the heat treatment, the annealed silicon wafer W is carried into the transfer chamber 2 and the atmosphere in the transfer chamber 2 is replaced with an inert gas such as N _2. Measure the moisture in the atmosphere with
After confirming that the water content has been sufficiently reduced, the silicon wafer W is transferred into the process chamber 1.

The inside of the process chamber 1 is purged with a purge gas of an inert gas such as N ₂ , and the wafer W is baked (heated) to a predetermined temperature while the silicon wafer W is loaded. During the baking, the atmospheric gas in the process chamber 1 is constantly introduced into the moisture meter 5 while adjusting the inflow amount, and the moisture concentration is measured. The pressure in the process chamber 1 is constantly measured by the pressure gauge 7.

After the baking is completed and the water concentration is within an appropriate range, SiCl ₂ H ₂ , HCl,
By introducing a reactive gas such as H ₂ and SiH ₄ , the gas of FIG.
As shown in (1), selective epitaxial growth is performed on the surface of the silicon wafer W. At this time, as in the case of the baking, the water concentration and the pressure in the process chamber 1 are constantly measured.

After the completion of the epitaxial growth, the inside of the process chamber 1 is replaced with an inert gas, and the grown silicon wafer W is unloaded from the unloading load lock chamber 4 via the transfer chamber 2.

As described above, in this embodiment, the silicon wafer W is heat-treated at a temperature of
Since the O film 10 is changed to the modified LTO film 11, the moisture contained in the LTO film 10 formed by the CVD method is completely desorbed and is reformed to a film quality that does not reabsorb moisture. However, moisture does not desorb. Actually, as a result of moisture detection during the epitaxial growth in the case where the above heat treatment is performed on the silicon wafer with the LTO film and in the conventional case where the heat treatment is not performed, the conventional method that does not perform the heat treatment shows that the process chamber 1 In the case where the heat treatment was performed, almost no water was generated as in the case where the thermal oxide film was formed on the back surface.

Note that the present invention also includes the following embodiments. In the above embodiment, the reactive gas processing is applied to the vapor phase growth in which the epitaxial growth is performed.
Other processing techniques may be used as long as the processing for reacting the reactive gas with the wafer in the reaction chamber is performed. For example, a CVD method for forming another thin film on a wafer or a dry etching method for etching a wafer surface using a reactive gas may be employed.

[0026]

According to the method for producing a reactive gas processing wafer and the reactive gas processing method for a wafer of the present invention, a silicon wafer is heat-treated at a temperature of 700 to 1000 ° C. to modify a silicon oxide film. Therefore, all the moisture contained in the silicon oxide film formed by the CVD method is desorbed, and the film quality is changed to a film quality that does not reabsorb the water. Even in the temperature increasing step during the reactive gas treatment, the water is desorbed. Nothing. Therefore, even when using LTO having a high growth rate,
By the heat treatment, corrosion due to moisture hardly occurs in the reactive gas treatment, and heavy metal contamination can be prevented.

Further, according to the reactive gas processing apparatus of the present invention, the heat treatment chamber for heat-treating the silicon wafer at a temperature between 700 ° C. and 1000 ° C. before transferring the silicon wafer into the reaction chamber is provided separately from the reaction chamber. Therefore, moisture contained in the silicon oxide film on the back surface of the silicon wafer can be desorbed in advance in the heat treatment chamber and the film itself can be reformed. To prevent corrosion by water and heavy metal contamination.

[Brief description of the drawings]

FIG. 1 is a schematic overall plan view showing an epitaxial crystal growing apparatus according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view of a silicon wafer in which a main part showing a process according to an embodiment of the present invention is enlarged.

[Explanation of symbols]

 Reference Signs List 1 process chamber (reaction chamber) 10 LTO film (silicon oxide film) 11 modified LTO film BC chamber for bake (heat treatment chamber) W silicon wafer

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5F045 AB02 AC01 AC05 AC13 AC15 BB14 EB08 EN04 HA06 HA25 5F058 BA07 BC02 BF03 BH01 BH04 BJ01

Claims (3)

[Claims] 1. A method for producing a silicon wafer for performing a reactive gas treatment by reacting a reactive gas with a front surface, comprising: forming a silicon oxide film on a rear surface of the silicon wafer by a CVD method; After the process, the silicon wafer is heated from 700 ° C to 100 ° C.
A step of heat-treating the silicon oxide film at 0 ° C. to modify the silicon oxide film. 2. A reactive gas processing method for a wafer for reacting a reactive gas with a surface of a silicon wafer, wherein the silicon wafer is manufactured by the method for manufacturing a reactive gas processing wafer according to claim 1. A method for treating a reactive gas on a wafer, characterized in that it has been performed. 3. A silicon wafer having a silicon oxide film formed on its back surface by a CVD method is installed in a reaction chamber, and a reactive gas flowing into the reaction chamber reacts with a surface of the silicon wafer to perform a reactive gas treatment. A reactive gas, comprising a heat treatment chamber for heat-treating the silicon wafer at a temperature between 700 ° C. and 1000 ° C. before transferring the silicon wafer into the reaction chamber. Processing equipment.