JPH06163675A - Jig for semiconductor - Google Patents

Abstract

PURPOSE:To obtain excellent durability and the high cleanliness of the surface of a jig readily by cleaning by forming the jig for a semiconductor of silicon carbide on which a quartz film is formed. CONSTITUTION:A cassette board having the length of 150mm, the width of 52mm and the thickness of 6.0mm is manufactured of silicon carbide material. The board is submerged into fluoric acid solution and sufficiently rinsed. Then, the board is dried on a clean bench. Thereafter, the board is inserted into a furnace. The temperature is increased and baking is performed in oxidizing atmosphere. Then, cleaning is completed. The board is set in a PVD furnace. Oxygen gas of 20 liter/min., hydrogen gas of 90 liter/min. and SiCl4 of 55g/min. are burned, and quartz is deposited on the surface of the base material. Then, the board is taken out of the furnace, and the comb shape of the quartz is corrected and machined. As the cleaning method for the jig, the jig is submerged into the fluoric acid of 5-10% and sufficiently rinsed with pure water.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor jig which is used for a semiconductor diffusion furnace which is subjected to heat treatment especially in a semiconductor manufacturing process.
In addition, the present invention relates to a semiconductor jig in which the surface of the jig can be easily cleaned by cleaning.

[0002]

2. Description of the Related Art Conventionally, as a jig for a semiconductor diffusion furnace,
Quartz members are often used because they are excellent in purity, and surface impurities can be easily removed by washing, resulting in a high level of surface cleanliness. When the temperature exceeds ℃, the deformation gradually starts, and therefore there is a problem that the life is short when used in a high temperature process of semiconductor manufacturing.

Therefore, in the process of manufacturing a semiconductor such as a Si wafer, a diffusion furnace (oxidation furnace) for heat-treating a semiconductor has a reaction tube (process tube) and a curing furnace because it has excellent heat resistance. A silicon carbide material is used in which tools (wafer boat, plate, support, etc.) are made of silicon carbide. Since the Si wafer is placed on a boat, loaded into a process tube and subjected to heat treatment, the base material of these members has a high purity, and the impurities on the surface are removed during use to achieve a high cleanliness. Is required.

Therefore, silicon carbide members such as process tubes and jigs must be sufficiently cleaned before and during the period of use. In this case, the cleaning method is wet hydrofluoric acid cleaning. After that, the method of setting in a diffusion furnace and dry-cleaning at high temperature using hydrochloric acid gas is generally adopted.

The cleaning method will be described in detail below.
First, 5 to 10% of materials such as process tubes and boats
After being dipped in the hydrofluoric acid solution, the wet cleaning is performed by sufficiently rinsing with pure water. If the tube or jig is made of quartz, it can be used simply by performing such wet cleaning. However, in the case of a silicon carbide material, wet cleaning alone is not sufficient, and the original characteristics of silicon carbide are exhibited. In order to do so, after the above-mentioned wet cleaning, it is necessary to carry out dry baking using a baking furnace or hydrochloric acid gas in the diffusion furnace to remove impurities existing on the surface of the silicon carbide material as chloride gas. is there.

[0006] In this dry cleaning, a tube and a jig that have been wet cleaned are set in a diffusion furnace, heated to a high temperature of 1200 ° C or more while flowing dry oxygen gas, and then several percent hydrochloric acid gas is supplied for 24 to 48 hours or more. For 24 to 4 hours, and then the hydrochloric acid gas is turned off to remove residual chloride.
This is a cleaning method in which air baking is performed for 8 hours or more, which requires a long time of 3 to 5 days or more.

The reason why it is difficult to clean the silicon carbide member is not clear, but since the member surface is finally finished by sandblasting, there are irregularities and pores on the member surface, and these irregularities and pores are present. Impurities tend to remain,
It is also presumed that the surface area is large and the total surface area is large, and the amount of impurities on the surface of the member naturally depends on the total surface area.

[0008]

As described above, the quartz member has high characteristics in terms of purity and surface cleanliness, but it may be consumed by the use of several batches and its life is short. There is a problem.

On the other hand, although the silicon carbide material is excellent in heat resistance and durability, it takes a long time to clean the surface to remove impurities, and there is a limit in reaching the cleanliness level by the cleaning. However, there is a problem that the cleanliness varies widely and the characteristics during use are not stable. In addition, even if the cleaning is performed for a long time as described above, after the dry cleaning, the wafer is mounted on the silicon carbide-based member and a contamination evaluation test is performed. Therefore, it takes a long time to repeat the process several times until the silicon carbide-based member is ready for use, so that the dry cleaning process may reduce the productivity of semiconductors. This is a cause of rising production costs.

The present invention has been made in view of the above circumstances.
It is an object of the present invention to provide a semiconductor jig that has excellent durability and that can be easily cleaned to provide a highly clean jig surface.

[0011]

Means and Actions for Solving the Problems As a result of intensive studies to achieve the above object, the present inventor has found that a jig for semiconductor is formed by forming a silicon carbide based substrate on which a silica coating is formed. It has been found that it is possible to obtain a semiconductor jig having both the advantages of quartz and the advantages of silicon carbide. That is, since the dry cleaning which has been conventionally required for the silicon carbide-based member is not necessary, the cleaning time can be greatly shortened, and the surface cleanliness can be easily made to have the same high characteristics as silica glass. Also, in terms of durability, it is possible to use several tens of batches or more under the condition that the conventional quartz glass jig is deformed in 3 to 4 batches and cannot be used. Since the material is solid, it was found that the material can be easily regenerated, and the present invention has been completed.

The present invention will be described in more detail below. The semiconductor jig of the present invention comprises a silicon carbide base material having a silica coating.

Here, the silicon carbide base material is not particularly limited, and those manufactured by, for example, a reaction sintering method, a recrystallization method, an atmospheric pressure method or the like can be used. The thickness of the silica (SiO ₂ ) film formed on the surface of the base material is preferably 1 mm or less, particularly 0.1 to 0.5.
It is preferably mm. The thickness of the quartz coating is 1 mm
If it exceeds, the peeling of the silica coating tends to occur due to the difference in thermal expansion from the silicon carbide substrate. In order to prevent this peeling, it is effective to increase the irregularities on the surface of the silicon carbide base material and, in some cases, provide a treatment such as providing a groove.

To form a quartz film on the silicon carbide substrate, a welding method or a PVD method (physical vapor deposition method) can be adopted. In either case, in order to prevent devitrification of the quartz glass at the time of heating, it is preferable to sufficiently wash and air-bak the silicon carbide material. When using the welding method, quartz is placed on a silicon carbide base material, and the quartz is heated to 2,000 ° C. or higher by an oxygen / hydrogen gas burner in an oxidizing atmosphere to melt and weld the quartz to the silicon carbide base material. By doing so, a silica coating can be formed on the silicon carbide surface. Also,
When the PVD method is used, a silicon carbide based substrate is placed in an oxidizing atmosphere, and oxygen, hydrogen, S
By burning the iCl ₄ gas, a quartz (SiO ₂ ) coating can be formed on the surface of the silicon carbide substrate. The oxygen gas flow rate at this time is 5 to 50 liters / mi.
n. , Hydrogen gas flow rate is 10-100 liters / mi
n. , SiCl ₄ gas flow rate is 10 to 50 g / min.
It is preferable that

The jig thus obtained can be used in the same manner as a conventional jig, but the method of cleaning the jig according to the present invention may be the same as that of the quartz jig. Specifically, after immersing in a 5 to 10% hydrofluoric acid solution, sufficient rinsing with pure water is sufficient, and it is not necessary to perform dry baking using air baking or hydrochloric acid gas as a cleaning method.

[0016]

EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited to the following examples.

[Examples, Comparative Examples 1 and 2] Silicon carbide base material (SEN-8000 manufactured by Shin-Etsu Chemical Co., Ltd.) with a length of 1
A cassette boat shown in FIGS. 1 and 2 having a size of 50 mm, a width of 52 mm and a thickness of 6.0 mm was manufactured. The cassette boat was immersed in a 7% hydrofluoric acid solution for 1 hour, rinsed thoroughly with pure water, and then dried on a clean bench for 24 hours. Then
Insert it in the furnace and raise the temperature to 1280 ° C in an oxidizing atmosphere.
It was baked for 8 hours to complete the washing.

The boat was set in a PVD furnace and oxygen gas was set at 20 liter / min. , Hydrogen gas 80 liter / m
in. , SiCl ₄ gas 55 g / min. Burn,
Quartz was deposited on the surface of the base material to a thickness of about 0.3 mm. The boat was taken out of the PVD furnace, and the comb shape of the precipitated quartz was corrected while heating with a gas burner. Then S
The manufacturing was completed by carrying out groove processing for mounting the i-wafer.

For comparison, a cassette boat having the same shape as that of the example was manufactured with a quartz substrate (manufactured by Shin-Etsu Quartz Co., Ltd.) and a silicon carbide substrate (SEN-8000 manufactured by Shin-Etsu Chemical Co., Ltd.). (Comparative Examples 1 and 2).

Next, the cassette boats of Examples and Comparative Examples 1 and 2 manufactured as described above were added to a 5% HF solution at 60%.
After soaking for a minute, it was thoroughly rinsed with pure water and then dried by being dried in a clean bench for 24 hours for cleaning.

Next, evaluation tests of these cassette boats were conducted. The test method was to load Si wafers (CZ-P type, <111>) into the cassette boats,
A heat treatment was performed in oxygen in a diffusion furnace at 1150 ° C. for 30 minutes. In order to examine the contamination degree of the Si wafer at this time, the lifetime of the wafer was measured. The results are shown in Table 1.
Note that the lifetime of the wafer becomes longer as the contamination is smaller.

[0022]

[Table 1]

[0023]

According to the present invention, it is possible to obtain a jig for semiconductors which is excellent in durability and can easily make the jig surface highly clean by simple cleaning.

[Brief description of drawings]

FIG. 1 is a plan view showing a cassette boat used in Examples and Comparative Examples of the present invention.

FIG. 2 is a side view of the example.

Claims (1)

[Claims] 1. A jig for semiconductors comprising a silicon carbide base material on which a silica coating is formed.