JP2837336B2 - Method of manufacturing quartz glass product for semiconductor heat treatment - Google Patents

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 quartz glass product for heat treatment of a semiconductor, and more particularly to a method for producing a quartz glass product in which a plurality of wafers are heat-treated in a furnace tube in a state where a plurality of wafers are arranged vertically or horizontally. The present invention relates to a method for accurately setting a groove pitch of a wafer boat within a dimensional tolerance.

[0002]

2. Description of the Related Art Conventionally, a wafer supporting boat used for accommodating a semiconductor wafer in a core tube arranged horizontally, for example, generally forms a hull-shaped frame using quartz glass rods and has a longitudinal inside of the frame. In many cases, a large number of wafer support grooves are formed at predetermined intervals in the direction, and a large number of semiconductor wafers are arranged almost vertically on the wafer support grooves. (JP-A-56-145123
issue)

Further, as shown in, for example, Japanese Patent Application Laid-Open No. 60-243272, a cylindrical body having a sealed structure in which the front and rear ends are closed by end plates is divided into two along the axial direction to form a half cylinder. A plurality of rail members are fixed in parallel on the inner peripheral surface side of the lower semi-cylindrical body, and a wafer support groove for supporting the wafer upright on the plate-like member is formed. A large number of processing gas through holes were formed along the direction, and a number of processing gas through holes were further formed around the upper and lower semi-cylindrical bodies between the support grooves and near the end plate edge surface, and a wafer was disposed from the processing gas through hole. There are also wafer support boats configured to allow the reaction gas to enter the cylinder.

Further, as shown in FIG. 2, a wafer supporting boat used for accommodating a semiconductor wafer in a furnace tube having a vertical structure has disk-shaped end plates 101, 10 arranged vertically.
Between two, three to four rods 104 are erected on one side on one side so that a circular space can be formed inside, and the end plates 101 and 102 are fixed to both ends thereof.
A plurality of wafer support grooves 103 are formed in the vertical direction on the inner peripheral side of the rod 104, and a large number of semiconductor wafers (not shown) are stacked and arranged in an internal space surrounded by the wafer support grooves 103. There are many.

[0005]

In order to save labor and prevent unnecessary dust from adhering, each of these support boats has a structure in which a large number of wafers are mounted on wafer support grooves by automatic loading. It is necessary to form the support groove pitch precisely with a predetermined dimensional tolerance in order to remove the support groove. There is a method of assembling into each of the above-mentioned shapes using fire processing or the like, and another method of engraving a support groove after assembling into a predetermined shape using the above-mentioned quartz glass rod or end plate. In either method, it is necessary to perform a heat treatment such as an annealing treatment before shipment as a final product in order to remove distortion or the like. For this reason, especially in the method of assembling the grooved rod, the groove rod expands and contracts due to the difference between the virtual temperature of the material at the time of groove cutting and the virtual temperature set after the heat treatment, and the cutting process is performed. Even when the support groove is cut with high precision, the one that was within the tolerance at the time of the groove cutting often deviates from the tolerance in the final product. An object of the present invention is to provide a method for manufacturing a quartz glass product for a semiconductor, particularly a wafer boat, which can be accurately set within a tolerance in a final product in view of the drawbacks of the conventional technology.

[0006]

SUMMARY OF THE INVENTION The inventor of the present invention has found that the dimensional deviation in the wafer support groove engraving time and the final product after the annealing treatment is different from the virtual temperature (FT ₁ ) of the quartz glass material at the time of the support groove engraving. , Virtual temperature in the final product (F
T ₂ ) It was found that the difference was caused by the difference, and the present invention was made based on the finding.

That is, the present invention relates to a quartz glass wafer board.
In the method of manufacturing wafers, quartz
Virtual temperature of glass material (FT₁), While detecting said support
In the final product obtained through the specified heat treatment after the groove is cut
Set the virtual temperature to (FT 2) If the above, the quartz
When machining a support groove in a glass material,
Groove processing is performed taking into account the pitch width, and
Within the specified dimensional tolerances.
It is characterized by the following. R = L × ｛1 / [1 + xx × (FT₁-FT_Two)]｝ R: Distance between multiple parts corrected for expansion and contraction due to FT
Is the pitch width (mm) x: the expansion and contraction coefficient (1 × 10^-7
~ 5 × 10^-6) (℃^-1L: Distance or distance between multiple parts required for the final product
Switch width (mm)

It is to be noted that the present invention is not limited to the above-mentioned wafer boat, and is also intended to perform one or more heat treatments after subjecting a plurality of portions of a quartz glass material to predetermined processing such as a distance between furnace tube flanges. The method may be applied to a method for manufacturing a quartz glass product for a semiconductor, for example, in which the processing between the plurality of parts is performed in consideration of the distance or the pitch width between the plurality of parts in the above formula.

[0009]

The operation leading to the present invention will be described step by step. First, a quartz glass rod or quartz glass plate that constitutes a wafer boat is manufactured by melting the raw material quartz powder at a temperature of 1900 to 2100 ° C. using an oxyhydrogen flame or an electric resistance heating element to produce a quartz glass ingot or quartz glass block. Then, these are processed to form a quartz glass rod or a quartz glass plate. Since the quartz glass rod and the quartz glass plate are both melted at a temperature of 1900 to 2100 ° C. and then cooled and solidified by natural cooling, the virtual temperature inevitably increases, and generally a virtual temperature of about 1500 ° C. Temperature.

[0010] This fictitious temperature means that, for example, when the glass is rapidly quenched from the transition temperature range or higher, for example, from T ₁ , the glass is cooled to room temperature while the atomic arrangement and density corresponding to the temperature T ₁ are frozen, In this case, the temperature T
₁ is called fictive temperature, the more the cooling time is gradually cooled, the more stable the glass, the lower the fictive temperature.However, in terms of manufacturing efficiency, extreme slow cooling is impossible, and softening is also difficult. If the state continues for too long, deformation or the like is likely to occur.

On the other hand, the difference in the virtual temperature is expressed as a difference in the atomic arrangement and the density, which is also expressed as a difference in the amount of contraction and expansion of the quartz glass material itself. That is, if there is a difference between the virtual temperature of the material at the time of grooving of the wafer support groove and the virtual temperature set by the subsequent firing / annealing, the quarted quartz glass rod expands and contracts,・ The groove pitch, cumulative groove pitch, etc. change from the time of cutting the groove.

In particular, in the case of the automatic loading type, the accumulated groove pitch has a tolerance of 500 to 8 mm.
It is often ± 0.1 mm for a quartz glass rod of 00 mm, and when the fluctuating amount of fictive temperature is large, the fluctuating amount is also large, and what was within the tolerance at the time of grooving deviated from the tolerance in the final product. Is happening occasionally. There is a difference between the virtual temperature of the material at the time of grooving and the virtual temperature set by annealing, so that the groove bar expands and contracts, and the groove width, groove pitch, cumulative groove pitch, etc. differ from those at the time of groove cutting. , The final product is rejected and the yield is low.

Therefore, the virtual temperature of the rod for cutting the groove is measured in advance, and the amount of change between the time of groove cutting and the time of the final product is measured from the difference between the estimated virtual temperature of the final product and that of the final product. Is corrected at the time of grooving. This allows the accumulated groove pitch to be within the tolerance at the time of the final product. Specifically, when performing the supporting groove processing on the quartz glass material, the groove pitching processing is performed in consideration of the groove pitch width based on the above equation, and the groove pitch width cut by this correction is used in the subsequent boat assembly. The quartz glass material expands and contracts due to the change in the virtual temperature of the material due to fire processing and annealing,
In the final product, a desired pitch width is obtained.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be illustratively described in detail below with reference to the drawings. However, unless otherwise specified, 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 thereto, but are merely illustrative examples. It's just FIG. 2 shows a vertical wafer boat 1 to which the present invention is applied.
00, three to four quartz glass rods 104 are erected on one side on the peripheral side so that a circular space 105 is formed between the disk-shaped end plates 101 and 102 disposed vertically. The end plates 101 and 102 are fixed to both ends thereof, and a number of wafer support grooves 103 are formed in the vertical direction on the inner peripheral side of the quartz glass rod 104 so as to form an inner space surrounded by the wafer support grooves 103. In this embodiment, a large number of semiconductor wafers (not shown) are stacked.

In such a boat, the quartz glass rod 104 before the groove cutting is performed by using a raw material quartz powder at 1900 to 2100 ° C.
The quartz ingot produced by melting at the temperature of
It was drawn out while melting / naturally cooling at a temperature of 2100 ° C. to obtain a quartz glass rod 104 of, for example, 20φ, and its virtual temperature was measured to be 1500 ° C. Next, the quartz glass rod 104 was heat-treated at 1800 to 1150 ° C for a predetermined time under the same heat-treating conditions as those for actually producing a boat, and then gradually cooled to sample a part. Was.

The measurement of the virtual temperature is performed based on a Raman spectrophotometer. That is, to explain the measuring method, first, as a comparative sample, a small piece (5 cm square, 20 m long) of synthetic silica glass having an OH group of about 500 (wt.ppm)
m) was prepared, and this small piece was heated at 1200 ° C. for 2 hours and then quenched in water. Sample 1 was heated at 1000 ° C. for 20 hours and then quenched in water 2.
After heating for 0 hours, sample 3 was quenched in water and produced.
After heating at 00 ° C. for 1200 hours , sample 4 which was quenched in water was formed, and these samples were each measured in the range of 150 to 650 cm ^{-1 with} a Raman spectrophotometer, and the following three peaks were measured.

150 to 650 cm ^-1 (W1, peak area AW1), 470 to 520 cm ^-1 (D1, peak area AD1) 580 to 640 cm ^-1 (D2, peak area AD2) Next, D2 is calculated from these three peak areas. Of the peak area (I) is determined. I = {AD2 / (AW1-AD1-AD2)} The relationship between this (I) and the fictive temperature is shown in a graph, and the fictive temperature is estimated from I of the sample whose fictive temperature is not known as a standard line (calibration curve). It is.

When the change amount of the groove pitch before and after the annealing process is calculated according to the above equation based on the virtual temperature, the change amount per 786 mm based on the design dimension is +0.24 mm, and the change amount per one groove pitch is obtained. Is 0.24 / 131 = 0.018 mm. Therefore, the actual pitch at the time of grooving in consideration of the correction amount is 6-0.001.
8 = 5.9998 mm. Therefore, the cumulative pitch obtained by cutting the support groove 103 at the corrected pitch of 5.998 mm with respect to the designed groove pitch width of 6 mm is 5.9 in calculation.
In contrast to 98 × 131 = 785.738 mm, the actual cumulative pitch of the quartz glass rod was 785,752 mm. This is +0.014 m with respect to the accumulated pitch after correction.
In consideration of the accuracy of the cutting machine, which is -0.248 mm with respect to m and the design cumulative pitch, cutting could be performed at the corrected groove pitch as intended.

Next, the quartz glass rod 104 grooved at the above-mentioned correction pitch is assembled with the end plates 101 and 102 by the above-described method to produce the boat 100 shown in FIG. 2, and the final product after the annealing treatment is performed. The cumulative pitch of the support grooves 103 is 785.960 mm and the designed cumulative pitch is 786 mm.
-0.04mm and cumulative pitch tolerance ± 0.1mm
Could fit within. In this case, the change amount of the cumulative groove pitch due to the processing is +0.208 mm, which substantially coincides with the change amount +0.24 mm predicted based on the above equation from the change in the virtual temperature. 13mm at 6mm without correcting the groove pitch width
When 2 grooves are cut, the cumulative pitch is calculated as 6 × 131 = 786
The actual measurement was 785.982 mm. Next, the quartz glass rod 104 was formed into a quartz glass boat in the same manner as in the embodiment, and the cumulative pitch of the support rod 103 of the final product after the annealing treatment was 786.222. It could not fit within ± 0.1 mm. Therefore, the theory of the present invention was proved to be correct.

[0020]

As described above, according to the present invention, after a plurality of portions of a quartz glass material are subjected to a predetermined processing, one or a plurality of heat treatments are performed to produce a desired quartz glass product for a semiconductor. In the method, it is possible to obtain a quartz glass product for a semiconductor, particularly a wafer boat, which can be accurately kept within the tolerance in the final product even if the virtual temperature before and after the heat treatment is different, so that the final product has deviated from the tolerance so far. , No more rejected products
The yield is improved. And so on.

[Brief description of the drawings]

FIG. 1 is an enlarged view of a wafer support groove of the quartz glass rod of FIG.

FIG. 2 is a perspective view of a wafer boat to which the present invention is applied.

[Explanation of symbols]

 REFERENCE SIGNS LIST 100 Vertical wafer boat 101, 102 End plate 104 Quartz glass rod 103 Wafer support groove

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Kyoichi Inaki 88, Kawakubo, Kanaya, Tamura-cho, Koriyama-shi, Fukushima Shin-Etsu Quartz Co., Ltd. Shin-Etsu Quartz Co., Ltd. Quartz Research Laboratory (56) References JP-A-7-14763 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 21/22 511 H01L 21/22 501 H01L 21/205 H01L 21/68

Claims (2)

(57) [Claims] 1. A method for producing a target quartz glass product for semiconductor heat treatment by subjecting a plurality of portions of a quartz glass material to predetermined processing and then performing one or more heat treatments, wherein Virtual temperature of quartz glass material (FT ₁ )
When the fictive temperature set in the final product after the completion of all the heat treatments is defined as (FT ₂ ), the distance or pitch width between a plurality of parts is taken into account by the following equation. A method for producing a quartz glass product for heat treatment of a semiconductor, comprising: R = L × {1 / [1 + xx × (FT ₁ −FT ₂ )]} R: Distance or pitch width (mm) between a plurality of parts corrected for expansion and contraction due to FT x: Expansion and contraction coefficient (1) due to FT change of quartz glass × 10 ^{-7 to} 5 × 10 ^-6 ) (° C ^-1 ) L: Distance or pitch width (mm) between a plurality of parts required in the final product 2. A method for manufacturing a quartz glass wafer boat, comprising detecting a virtual temperature (FT ₁ ) of a quartz glass material on which a wafer support groove is carved, and performing a predetermined heat treatment after carving the support groove. When the virtual temperature set in the final product is (FT ₂ ), when performing the support groove processing on the quartz glass material, the groove cutting process is performed in consideration of the groove pitch width based on the above equation, and the final product is formed. 2. The method for producing a quartz glass wafer boat according to claim 1, wherein the obtained groove pitch width is kept within a predetermined dimensional tolerance.