JPH01126238A - Quartz glass member - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is applicable to the heat treatment process of semiconductor wafers, which are useful as quartz glass members, particularly quartz glass furnace core tubes and Pel jars used in the semiconductor industry. The present invention relates to a quartz glass member that can reduce deflection, deformation, and warpage.

(Prior Art) Quartz glass members are commonly used as jigs for heat treatment of semiconductor wafers due to their high purity and ability to withstand high temperatures.
It has been proposed to coat the outer surface of a quartz glass member with a cristobalite layer for the purpose of preventing warping (Japanese Patent Publication No. 47-1477, No. 47-18).
(See Publication No. 83).

However, in order to manufacture a quartz glass tube with a layer of cristobalite, pure or powdered listopalite is sprayed onto the quartz glass tube, and then this is treated with a flame or heated in a furnace to convert the cristobalite into quartz. The process involves baking the surface of the glass tube and heating it at high temperatures for a long time to grow it into a fine crystal layer, which has the disadvantage that the processing time is long and the quartz glass tube can be crushed during this process. However, the quartz glass tube thus obtained has the disadvantage that it cannot be used in a clean room because the cristobalite layer causes dust.

(Structure of the Invention) The present invention relates to a quartz glass member which solves such disadvantages, and which has crystals of 5 to 1+ OOOgm in size that can grow into cristobalite crystals at high temperatures in the glass layer.
It is characterized by the presence of a large number of strain nuclei.

That is, as a result of various studies conducted by the present inventor on methods for preventing accidents caused by deformation, deflection, warping, etc. during heating of quartz glass products used in the semiconductor industry,
When strain nuclei are formed in the quartz glass layer and used at high temperatures in the semiconductor industry, these strain nuclei grow into cristobalite crystals relatively quickly, resulting in the quartz glass member having high mechanical strength. It was discovered that deformation, deflection, warpage, etc. do not occur even when used at high temperatures, and the present invention was completed by conducting research on methods for forming strain nuclei and preferred embodiments of strain nuclei.

For the quartz glass member of the present invention, a quartz glass product made by a conventionally known method may be used as a starting material. It may be made by thermoforming a glass matrix, which may also be transparent or translucent with microbubbles. In addition,
Normally, this material is considered to be transparent, but the translucent material containing microbubbles is only translucent due to the bubbles, and is not low in purity.

The content of alkali metals such as Li is tppm or less. In addition, this product has the effect of increasing the heat-uniforming effect during heating due to the fine bubbles, and furthermore, when the bubbles are in the shape of an ellipsoid, the direction of arrangement of the bubbles further enhances the heat-uniforming effect. Although this may be used, the size of the bubble may be such that an ellipsoidal bubble has a major axis of 15 to 1,0001 IM, and a true sphere has a diameter of 10 to 100 mm.

In order to form strain nuclei in this quartz glass member, for example, a nucleating agent may be attached to the surface of the quartz glass molded product and heat treated. Examples of this strain nucleating agent include zinc, magnesium, calcium, zirconium, soot, etc. , boronic acid, aluminum, phosphorus, diantimony and/or a compound of one of these elements are suitable; however, if the amount added is too small, the implantation will be reduced, and if the amount is too large, the surface of the quartz glass member will be damaged. becomes devitrified.

In addition, this heat treatment can be performed by heating the quartz glass member directly with a flame or in an electric furnace, but nucleation does not occur at a heating temperature of 1,000°C or lower, so 1. O
The molded product may be heated for 10 minutes to 10 hours at a temperature of OO'C or above, preferably 1.200 to 1,300 degrees Celsius.If the molded product is a tubular body and there is a risk that the tube may collapse due to high temperature heating. It is advisable to rotate this molded product appropriately.

The nucleating agent attached to the surface of the quartz glass member treated in this way penetrates into the glass layer, and nuclei are formed within the glass layer by heating, but these strain nuclei have a size of 5 μm. If it is less than fog, it will take a long time to grow into cristobalite crystals, so it will not be effective.
1. If it is larger than OOOIlm, it will no longer be the strain nucleus that is the object of the present invention, but will become a quartz glass member product that already has a cristobalite crystal layer.
The strain nucleus in the present invention is 1,00oII11 or less.

A quartz glass member containing these strain nuclei has a high mechanical strength at high temperatures, but the strain nuclei only need to be present at a depth of 100 .mu.- from the outer surface. Regarding the number of strain nuclei present, since these serve as nuclei for the growth of cristobalite crystals, if there are too few, the effect will be weak,
If it exceeds 1/IIa3, the outer surface will become cristobalite and cause dust, making it impossible to use it in a clean room.
10-10,000 pieces per unit, preferably 100-5,000 pieces
It is preferable that the number is in the range of 00.

(Effects of the Invention) The quartz glass member of the present invention contains strain nuclei that grow into cristobalite crystals at high temperatures in its glass layer, so when it is used for wafer processing in the semiconductor industry, this processing Since the process is carried out at a relatively high temperature, cristobalite crystals grow relatively quickly in this glass layer, resulting in high mechanical strength, which prevents it from bending, deforming, or warping during use. It has this advantage.

(Example) Next, examples of the present invention and comparative examples are given below. 6 Examples 1 to 5
, Comparative Examples 1 to 4 Natural crystal was melted with an oxyhydrogen flame to obtain an outer diameter of 202 m.

A transparent quartz glass furnace core tube 1 with a thickness of 6 cm was made, and a translucent quartz glass furnace core tube 2 containing microbubbles was also manufactured by electrically melting natural quartz. On the other hand, by applying an acidic solution containing aluminum ions to the outer surfaces of the furnace core tubes 1 and 2 made in the same manner as described above, and then heat-treating them, 75. Transparent quartz glass furnace core tube 3 with an average aluminum concentration of 200 ppm
1, and a translucent quartz glass furnace core tube 4 with microbubbles
made.

Next, rings 20 m in length were cut out from this furnace core tube 3.4 to make rings I and ring ■, and these rings were placed horizontally on a quartz glass hearth plate in a box-type electric furnace.
The rings were heated at 50"C for 10 hours or 1.300℃ for 30 minutes, then taken out and cooled. The average concentration of strain nuclei present in these rings and the size of the strain nuclei were measured, and the appearance was examined. For these rings, place them in a box-type electric furnace and put them in N at 1,200°C.
When the amount of crushing of the ring was measured after heating for 20 hours, the results shown in Table 1 were obtained.

Next, for comparison, the ring ■ obtained from the above transparent quartz glass furnace core tube 3 was not heat-treated (Comparative Example 1), and the ring ■ was placed horizontally in a box electric furnace.
Regarding the ring heated at 350°C for 24 hours (Comparative Example 2), we investigated the average concentration of strain nuclei present in the ring, the size of the strain nucleus, and the appearance, as well as the amount of collapse of the ring under the same heating conditions as above. When measured, the results shown in Table 1 were obtained.

In addition, the semiconductor silicone wafer was installed in a horizontal tubular furnace and heat treated at 1,200°C for 2,000 hours in this furnace.
The wafers heat-treated for 0 hours (Examples 3 and 4) have appropriate generation of strain nuclei, and therefore appropriate growth of cristobalite crystals, which increases mechanical strength and prevents bending and deformation during wafer processing. , Furnace core tube 3 where no warping occurred, but no strain nuclei were generated.
(Comparative Example 3) was crushed at a rapid stage before cristobalite crystal growth started.

1. Treated at 350"C for 24 degrees (Comparative Example 4)
Since the outer surface of the wafer had a cristobalite layer before it was installed in the horizontal tube furnace, this caused dust when it was installed, reducing the yield of wafers.

In addition, a 10% by weight solution of aluminum chloride was applied to the outer surface of the transparent quartz furnace core tube 1 obtained above, and a ring with a length of 20 mm was cut out from the furnace core tube that had been baked with a burner. After heating the ring at 1,250°C for 10 hours, it was cooled in the air, and a 100p thick piece of glass was cut from the outer surface of the ring using a low-speed cutter. When the strain nuclei were photographed at a magnification of 40 times using a polarization device of a stereomicroscope made by Komatsu, the results shown in Fig. 1 were obtained. As for time, the results shown in Figure 2 were obtained.

[Brief explanation of the drawing]

Figure 1 is a polarized light micrograph of a glass piece cut from a ring that was cut out after applying an aluminum chloride solution to the outer surface of the transparent quartz furnace core tube and baking it in an example, and then heat-treated at 1,250°C for 10 hours. Figure 2 shows a polarized light micrograph of a glass piece that was heated at 1,200°C for 5 hours.

Claims (1)

[Scope of Claims] 1. A quartz glass member characterized in that a large number of strain nuclei having a size of 5 to 1,000 μm exist in a glass layer, which can grow into cristobalite crystals at high temperatures. 2. The quartz glass member according to claim 1, wherein 10 to 10,000 strain nuclei exist per 1 mm^3 in the glass layer up to 100 μm from the outer surface. 3. The quartz glass member according to claim 1 or 2, wherein the quartz glass member is a transparent or semitransparent furnace core tube containing microbubbles.