JP3193181B2 - High heat resistant seal member - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat treatment apparatus for a semiconductor wafer, a high heat-resistant sealing member for sealing a flange portion through which a high-temperature fluid passes, and other high-temperature heat receiving portions by surface contact.

[0002]

2. Description of the Related Art Conventionally, as a high-temperature sealing member,
O-rings made of a heat-resistant resin such as a fluorine resin or silicone rubber have been used. Their heat resistance is about 200 to 300 ° C. In recent years, there has been a movement to form a seal member using a COPNA resin (Japanese Patent Publication No. 62-521, 522) in which a benzene ring having a methylene chain is crosslinked between condensed polycyclic aromatic compounds. However, such a sealing member also has a heat resistance of about 350 ° C., and a high degree of hermetic sealing cannot be expected because the COPNA resin has a significantly reduced elastic force as compared with a fluorine resin or a silicone rubber.

For this reason, a method of protecting the seal member by subjecting the seal portion exposed to a high temperature of 300 to 400 ° C. or more to water cooling or the like from the back side of a flange or the like has been generally considered. When the flange is made of a radiant heat permeable material such as quartz glass, heat is applied to the O-ring made of the heat-resistant resin even with water cooling, and in the case of a high heat conductive material such as silicon carbide, water cooling of the flange on the silicon carbide side is performed. Since it is impossible due to heat shock, high heat to the O-ring cannot be prevented in this case as well, and thermal deterioration of the O-ring received by the O-ring has been substantially unavoidable.

For example, in a semiconductor wafer heat treatment apparatus, as shown in FIG. 5, a cylindrical dome-shaped core tube 20 having an open lower end is mounted on a flange 21 provided at the lower end and a base 30. Quartz cap 2
A configuration is used in which an O-ring 24 is airtightly closed between the three, and a processing gas introduction port 22 provided immediately above the flange 21 is also connected to a gas introduction pipe 25 via a member corresponding to the O-ring 24. However, in the case of such a device,
In order to thermally keep the seal portion away from the heating portion where the heater 26 is surrounded, a heat insulating cylinder 27 is mounted on the quartz cap 23, and a semiconductor wafer 28 is placed on the upper surface of the heat insulating cylinder 27.
Are placed in a row, and a heater 26 is surrounded around a furnace tube 20 where the wafer boat 29 is located.
8 is configured to be heat-treatable.

[0005]

In such a heat treatment apparatus, heat is shielded from the space for wafer heat treatment (for example, having a temperature of 1100 to 1250 ° C.) through the heat retaining cylinder 27, and the flange 21 at the opening end of the furnace tube 20. Although the high temperature is prevented from propagating to the O-ring 24 and other sealing parts provided in the above, the height of the heat retaining cylinder 27 is required to lower the flange 21 and the like to the heat-resistant temperature range of fluorine resin or silicon rubber. Must be considerably high, and as a result the core tube 2
The effective heat treatment area within 0 is reduced. Even with the above configuration, a part of the high-temperature processing gas propagates heat to the seal portion and easily causes deterioration of the O-ring 24. Therefore, the toxic processing gas for semiconductor heat treatment deteriorates the O-ring 24. Therefore, there is a risk of leakage to the outside, and it is easy to cause a problem that the apparatus is damaged or the operator is adversely affected. Further, when the O-ring 24 is formed of a fluororesin or silicon rubber, the O-ring 24 is liable to be adversely affected by a gas generated from the resin or the like due to deterioration of the O-ring 24.

In view of the above technical problems, the present invention can ensure sufficient sealing performance even in a portion exposed to a high-temperature atmosphere of about 1300 ° C., as in the above-mentioned semiconductor heat treatment apparatus, and also has heat conduction and heat radiation. It is an object of the present invention to provide a seal member having a high heat-shielding property capable of shutting off the heat.

[0007]

According to the present invention, in order to achieve the above technical object, at least one of the parts is brought into surface contact with a part to be exposed to a high temperature to make a seal. In the sheet packing or other sealing member to be formed, an amorphous high-purity quartz glass foam layer composed of closed cells, particularly reduced-pressure closed cells, is disposed at least on the high-temperature sealing surface side. In this case, the entire sealing member may be formed of a foam layer, but a transparent quartz glass plate is formed by heat fusion or strong fire polishing on a low-temperature side of the foam layer,
The quartz glass plate and the low-temperature side contact surface may be configured to be in surface contact via an O-ring.

[0008]

According to this technical means, the bubbles themselves are deformed with a suitable elasticity by the amorphous quartz glass foam,
Since each of the bubbles is not a communicating bubble but a closed bubble, an airtight seal can be achieved without gas leakage or the like from the seal member. That is, more specifically, as shown in FIG. 1, a closed cell l located on the surface of the seal member 1
a is formed in the shape of minute irregularities (lapilince shape), and because the bubble la itself has an elastic force, when pressed by the flange 21, even if there is some irregularity in the sealing surface of the flange 21, this is absorbed. It is possible to seal hermetically with high accuracy. In this case, if the closed cell la of the seal member 1 is too large, a gap is formed by the pressing of the flange 21. Even if it is too small, the elastic function is lost and smooth sealing becomes difficult, so that the apparent density is reduced. 0.
2 to 1.2 g / cm ³ , 80% or more of air bubbles are 10 to 1
It is preferable to form it with closed cells having a diameter of 000 μm.

In particular, since the density and the bubble diameter are appropriately set,
Moderate elasticity due to the deformation of the bubbles (for example, the Young's modulus is 1/1 of 7.39 × 10 ³ Kg / mm ² of the Young's modulus of quartz glass)
0 to 1/4), the elasticity is maintained even when the sealing surface is in close contact with a high temperature, and it has high sealing properties because it is a closed cell 1a that does not allow gas to pass through.
Further, in the case of quartz glass, the softening point temperature is as high as 1600 ° C. or higher, so that the closed cells 1a can maintain a sufficient elasticity even at around 1300 ° C., and have extremely high heat resistance. However, quartz glass has high chemical stability and has no room for corrosion or the like, so that it is not limited to a portion to be sealed, and even if it is used for the flange 21 of a semiconductor heat treatment apparatus as described above. In addition, no gas serving as a semiconductor poison is generated in the processing space.

It is premised that the foam functioning as the seal member 1 is amorphous in order to maintain the elastic force. In this case, Na, K, Li, Cu, B, Ca, N
The amount of metal impurities contained in i, Fe, and Ce is 0.5
By setting the content to less than ppm, the elastic force can be maintained for a long time without devitrification or crystallization even when exposed to a high temperature of about 1300 ° C. for a long time. Further, when the OH group of the foam is 100 ppm or less and the nitrogen concentration is 0.0
By setting the content to 1% by weight or more, the heat resistance is further improved.

Further, since the closed cells la of the sealing member 1 are depressurized cells, they have heat shielding properties, can effectively prevent heat propagation and heat radiation to the low temperature side, and have improved ease of thermal shock. That is, even when the seal member 1 is made thin, the bubbles contained therein absorb the stress caused by the thermal shock, and do not break even when encountering a rapid thermal stress at a high temperature. Has. In addition, having a heat insulation property ensures that the mating surface on the low temperature side does not seize or stick, and that it is easy to disassemble, and that even if a high temperature of 1000 ° C. or more is received on the sealing surface on the high temperature side, it has a low temperature. It is easy to design such that the side is kept at 300 ° C. or lower, so that the O-ring 24 or the like can be used on the low temperature side. In this case, the entire sealing member 1 may be formed of a foam. However, in order to use the O-ring 24, a transparent quartz glass layer 11 is formed on the low temperature side of the foam layer 10, and the transparent quartz glass layer 11 is formed. The low temperature side contact surface may be formed into a surface contact movable via an O-ring 24 to form bubbles.
Thereby, heat conduction and heat radiation can be efficiently cut off on the foam layer side 10 and the transparent quartz glass layer 11 having a smooth surface makes contact with the O-ring 24, so that the sealing performance on the low temperature side is further improved. I do.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention unless otherwise specified, and are merely illustrative examples. Only. For example, when the ring-shaped sealing member 1 is formed, most of the metal forming the sealing member is placed in a cylindrical ring-shaped carbon crucible having an outer diameter slightly larger and an inner diameter slightly smaller than the outer shape of the seal packing. A hot-vapor-phase high-purity synthetic quartz glass fine powder having impurities of 0.5 ppm or less is filled with a quartz glass fine powder obtained by heat-treating for about 4 hours in an ammonia gas + nitrogen gas atmosphere at 800 ° C., and the temperature is reduced to 1650 to 1700 ° C. 1-3
Heat treatment is performed for about a few hours to fuse and foam the quartz glass fine powder, thereby obtaining a quartz glass foam having a large number of closed cells inside. Next, after the foam is cut in accordance with the inner and outer diameters of the sealing member 1, the cylindrical ring-shaped foam is cut to a predetermined thickness, and both front and rear surfaces functioning as a sealing surface are ground. As a result, the closed cells 1a are exposed on the surface of the sealing surface shown in FIG. In addition, of the said foam,
The apparent density was determined from the weight and the apparent volume, and the continuous porosity (volume ratio) for all the internal small spaces was determined from the apparent density and the increase in weight when immersed in the liquid, and the concentration of each metal impurity was determined by ICP analysis. When the OH group content was examined by a diffuse reflection spectrum method using FT-IR, the density of the foam was 0.2 to 1.2 g / cm ³ ,
0% or more is composed of closed cells having a diameter of 10 to 1000 μm,
And in the foam, Na, K, Li, Cu, B, C
A, Ni, Fe, Ce and the like are each formed of an amorphous material having a metal impurity content of 0.5 ppm or less, an OH group of 100 ppm or less, and a nitrogen concentration of 0.01 wt% or more.

FIG. 2B shows the ring-shaped sealing member 1.
Is mounted between the flange 21 of the open end of the quartz glass furnace tube 20 and the quartz cap 23, for example, to reduce the height of the heat insulating cylinder 27 and to form the sealing member. For example, even in the case of receiving high-temperature heat close to 1300 ° C., there is no risk of thermal deterioration, whereby the effective heat treatment effective space in the furnace tube 20 can be expanded, and the seal member 1 The base 30 is lifted and lowered with the flange 21 of the core tube 20 locked by the locking portion 29 because the peeling property at the contact surface is good and the burning or the like does not occur unlike the conventional packing. The flange 21 and the quartz cap 23 are easily separated from each other, and the replacement operation of the wafer boat 27 is facilitated.

FIG. 3A shows the structure of the flange 31 of the processing gas inlet 22, and reference numeral 21 denotes a quartz glass made at the open end of the processing gas inlet 22 connected to the furnace tube 20. The flanges 31 and 32 are made of a stainless steel gas introduction pipe 2.
The stainless steel flange provided at the opening end of the opening 5 interposes the sealing member 1 therebetween, and is fixed using a well-known bolt and nut. According to this embodiment, a flange 31 made of quartz glass and a flange 32 made of stainless steel are used.
Since the seal member 1 according to the present embodiment is interposed therebetween, heat from the furnace tube 20 transmitted from the processing gas introduction port 22 is blocked by the seal member 1 and is made of stainless steel. To the flange 32 side. Also,
Since the releasability at the contact surface is good, it is possible to prevent burning and the like.

FIGS. 3 (B) and 3 (C) show modified examples of the joint portion of the processing gas introduction flange 31. FIG. 3 (B) shows the cylindrical portions located on the inner peripheral side of the flanges 31 and 32, respectively. Let
The sealing member 1A also has a stepped groove on the inner peripheral side in accordance with this. 4B, the flanges 31 and 32 are formed to have convex or concave inclined parallel contact surfaces, respectively, while the seal member 1B is configured to have an arrow blade cross-sectional shape. According to this embodiment, as compared with the case of FIG. 3 (A), the contact area is large, the sealing performance is large, and the centering work of the flanges 31, 32 at the time of joining is simplified.

FIGS. 4A and 4B are views showing a seal member according to another embodiment of the present invention and the state of attachment thereof. The sealing member 50 is formed by thermally fusing a quartz glass plate 50B to one surface of the ring-shaped high-purity quartz glass foam layer 50A. Note that, instead of thermally fusing the quartz glass plate 50B, a foam layer 50 is used.
A fire policy may be strongly applied to one side of A to form a transparent flat transparent quartz glass layer. Such a seal member is interposed so that the foam layer 50A is located on the flange 21 at the open end of the quartz glass furnace core tube 20 and the transparent quartz glass layer 50B is located on the quartz cap 23 side, as shown in FIG. At the same time, an O-ring 24 is arranged between the quartz cap 23 and the transparent quartz glass plate 50B. According to this embodiment, by using the O-ring 24 in combination with the flat surface of the sealing member on the side of the quartz glass plate 50B, the foam layer 50A has a high thermal insulation property so that the O-ring 24 can be adjusted to an appropriate temperature suitable for the usage characteristics. By lowering, the O-ring 24 can completely secure the sealing performance. Therefore, since the O-ring 24 having good sealing performance can be used at one place as compared with the case of FIG. 2, high sealing performance can be secured while maintaining the durability of the O-ring 24.

[0017]

As described above, according to the present invention, sufficient sealing performance can be ensured even in a portion exposed to a high-temperature atmosphere of about 1300 ° C., such as a semiconductor heat treatment apparatus, and heat conduction and heat radiation are also achieved. A high heat-blocking sealing member capable of blocking the heat can be obtained. And so on.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a main part showing a seal structure of a seal member of the present invention.

FIG. 2A is a perspective view showing a high heat-resistant sealing member according to a first embodiment of the present invention. (B) is a vertical sectional view of a main part in which the seal member shown in (A) is incorporated in a semiconductor heat treatment apparatus.

FIGS. 3A, 3B, and 3C are exploded perspective views showing several modified examples of a ring-shaped seal member used for a joint portion of a flange.

FIG. 4A is a perspective view showing a high heat resistant seal member according to a second embodiment of the present invention. (B) is a vertical sectional view of a main part in which the seal member shown in (A) is incorporated in a semiconductor heat treatment apparatus.

FIG. 5 is a longitudinal sectional view showing a usage state of a seal member at a flange joint of a conventional vertical heat treatment furnace.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Seal member 1A Seal member 1B Seal member 1C Seal member 50 Seal member 21 Flange 31 Flange 32 Flange 23 Quartz cap 50A Foam layer 50B Transparent quartz glass plate

Claims (7)

(57) [Claims] 1. A sealing member for sealing by bringing at least one of them into surface contact with a portion exposed to high temperature, wherein amorphous high-purity quartz glass foam comprising elastic closed cells at least on the high-temperature sealing surface side. A highly heat-resistant seal member having a body layer disposed thereon. 2. The highly heat-resistant sealing member according to claim 1, wherein said closed cells are formed of reduced-pressure closed cells. 3. The foam layer has an apparent density of at least 0.2 to 1.2 g / cm ³ on the high-temperature sealing surface side, and 80% or more of the cells are closed cells having a diameter of 10 to 1000 μm. High heat-resistant sealing member. 4. A transparent quartz glass layer is provided on the low-temperature side of the foam layer, and the quartz glass plate and the low-temperature side contact surface can be brought into surface contact via an O-ring.
The highly heat-resistant sealing member as described in the above. 5. The quartz glass foam according to claim 1, wherein Na, K, L
The highly heat-resistant seal member according to claim 1, wherein the metal impurity content of each of i, Cu, B, Ca, Ni, Fe, and Ce is 0.5 ppm or less. 6. The quartz glass foam has an OH group of 100.
2. The highly heat-resistant seal member according to claim 1, wherein the content of nitrogen is 0.01 ppm by weight or less. 7. Foaming constituting the quartz glass foam layer
The Young's modulus of the body is 1/10 to 1/1 / the Young's modulus of quartz glass
The high heat-resistant seal member according to claim 1, wherein