JPH0963977A - Semiconductor heat treatment device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a semiconductor heat treatment device on which the whole heat shielding body is prevented from excesive etching, a long life can be ensured and working efficiency can be improved. SOLUTION: A plurality of high purity quartz glass plates 8 and 10, containing microscopic bubbles, are juxtaposed (9 and 11) between a heat treatment region and a non-heat treatment region leaving intervals, and the quartz glass plates are connected in such a manner that they can be separated at least into two groups.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor heat treatment apparatus for performing heat treatment such as oxidation, diffusion and annealing on a silicon wafer for semiconductor devices such as LSI.

[0002]

2. Description of the Related Art Conventionally, as a semiconductor heat treatment apparatus of this type, heat insulation of a heat treatment area in which a silicon wafer group is stored,
In order to equalize the temperature and prevent the non-heat-treated region from burning, and to uniformly supply the processing gas to the surface of the silicon wafer, micro bubbles are included between the heat-treated region and the non-heat-treated region.
There is known a horizontal heat treatment furnace having a heat shield formed by arranging one or two high-purity quartz glass plates side by side with a space therebetween (see Japanese Utility Model Publication No. 6-14480). In this horizontal heat treatment furnace, a high-purity quartz glass plate containing microbubbles reflects and scatters the heat flux from the heat treatment area to the non-heat treatment area and equalizes the gas flow distribution, so The purpose is to prevent burning of the non-heat-treated region.

[0003]

However, in the conventional semiconductor heat treatment apparatus, since the heat shield has an integral structure,
There is a problem described below. That is, since the etching process performed as a maintenance for the adhered substances accompanying the CVD process is performed on the side of the heat-treated region where the adherence is the strongest, the non-heat-treated region side, which is originally unnecessary, is etched. The deterioration of the integrated heat shield as a whole progresses. In addition, the operation rate of the device is lowered by stopping the device to perform the regeneration process by etching. In particular, silicon wafers have a large diameter and
As the degree of integration of C increases, improving the operating rate of the device becomes an important issue for improving productivity. Further, in the conventional semiconductor heat treatment apparatus, since each high-purity quartz glass plate of the heat shield has the same density, if the amount of microbubbles is increased to increase the heat shield efficiency, the strength is lowered and the dust is reduced. Incidence increases. On the other hand, in order to increase the strength and prolong the life, it is necessary to reduce the amount of fine bubbles, which causes a problem that the heat shield efficiency is lowered. Therefore, it is an object of the present invention to provide a semiconductor heat treatment apparatus capable of preventing excessive etching of the heat shield as a whole, prolonging its life, and improving its operating rate. Another object of the present invention is to provide a semiconductor heat treatment apparatus in which the heat shield has sufficient strength and which can improve the heat shield efficiency while reducing dust generation.

[0004]

In order to solve the above-mentioned problems, a first semiconductor heat treatment apparatus of the present invention comprises a plurality of high-purity quartz glass plates containing microbubbles between a heat treatment region and a non-heat treatment region. Are juxtaposed at intervals and separably coupled to at least two groups. In the plurality of high-purity quartz glass plates, the average diameter of microbubbles is 200 μm or less, and the scattering coefficient is 200 to 1200.
It is preferable that m ⁻¹ and the density ρ are 1.7 ≦ ρ ≦ 2.2 g / cm ³ . The total number of the plurality of high-purity quartz glass plates is preferably 4 to 12, and the thickness of each plate is 4 to 10 mm. Further, in the second semiconductor heat treatment apparatus, a plurality of high-purity quartz glass plates containing microbubbles are juxtaposed at intervals between the heat treatment region and the non-heat treatment region, and the density of the high purity quartz glass plates is set from the heat treatment region side. It is characterized in that it is made different in at least two stages that are made smaller toward the non-heat-treated region side. Wherein the plurality of high-purity quartz glass plate, the density [rho heat treatment region side ^{1.9 <ρ ≦ 2.2g / cm 3} , 2 stages in the range of non-heat region side 1.7 ≦ ρ ≦ 2.1g / cm ³ It is preferable that they are different from each other. Further, the plurality of high-purity quartz glass plates may be made different in multiple steps so that the density ρ becomes smaller from the heat treatment region side to the non-heat treatment region side in the range of 1.7 ≦ ρ ≦ 2.2 g / cm ^3. Good.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. 1 and 2 are a vertical cross-sectional view of a vertical heat treatment furnace showing an embodiment of a semiconductor heat treatment apparatus of the present invention and an exploded perspective view of a main part thereof. In the figure, 1 is a cylindrical furnace core tube made of high-purity quartz glass and closed at the upper end and opened at the lower end. The furnace core tube 1 has an open end with a sealing member (not shown) such as an O-ring. It is hermetically sealed and stands vertically on the hearth 2. The furnace core tube 1 forms a heat treatment area in cooperation with a cylindrical heating element 3 that surrounds the outer periphery of almost the entire length excluding the lower end portion thereof, and this heat treatment area is formed by a heat insulating material 4 that forms the furnace body. Is covered. A heat shield 5 placed on the hearth 2 is housed in the lower end of the furnace core tube 1 which is a non-heat treatment area, and on the heat shield 5 is made of high-purity quartz glass, A wafer boat 7 in which silicon wafers 6 are stacked and mounted at appropriate intervals is placed in the heat treatment area. The heat shield 5 reduces the amount of heat that directly reaches the hearth 2 by reflecting and scattering the heat flux from the heat treatment area to the non-heat treatment area. The heat shield 5 has three circular high-purity quartz particles containing microbubbles. A plurality of high-purity quartz glass plates 8 are formed by connecting a plurality of high-purity quartz glass support columns 9 at predetermined intervals to each other, a heat treatment side portion 5a, four circular high-purity quartz glass plates 10 containing microbubbles. Non-heat treatment side part 5b connected by glass columns 11 at a required interval
It is composed of Both parts 5a and 5b are provided with a plurality of dowel holes 12 provided in the high-purity quartz glass plate 8 at the bottom of the heat-treated side part 5a, and the non-heat-treated side part 5 corresponding thereto.
It is separably connected in series by a dowel 13 made of high-purity quartz glass protruding from the high-purity quartz glass plate 8 at the top of b.

High-purity quartz glass plates 8 and 10 of the heat shield 5
Is an average diameter of microbubbles of 200 μm or less and a scattering coefficient of 2
00 to 1200 m ^-1 , density ρ is 1.7 ≤ ρ ≤ 2.2 g /
cm ³ When the average diameter of the micro bubbles exceeds 200 μm, the mechanical strength becomes small and the scattering coefficient becomes 200 m ^−1.
If it is less than 12, the heat-shielding effect is sharply reduced, while
If it exceeds 00 m ^-1 , the heat shielding effect will be large, but the mechanical strength will be small and the generation of dust will be large, and if the density ρ is less than 1.7 g / cm ³ , the strength will be reduced and the dust will be reduced. However, when the amount exceeds 2.2 g / cm ³ , the heat shielding effect sharply decreases. More preferably, the average diameter is 20 to 120 μm. The plurality of high-purity quartz glass plates 8 and 10 have a number of 4 to 12 and a thickness of 4 to 10 mm. If the number is less than 4,
While the heat flux cannot be sufficiently shielded, when the number of sheets exceeds 12, the reduction rate of the heat flux becomes almost constant, the effect reaches the ceiling, and when the thickness per sheet is less than 4 mm,
While the heat shielding effect is not sufficient, if it exceeds 10 mm, the heat shielding effect cannot be expected so much for the thickness, and rather the heat capacity is adversely affected. More preferably, the number is 6-9.

In the vertical heat treatment furnace having the above structure, it is possible to remove the heat treatment side portion 5a having strong adhesion and replace it with a new one, so that the heat treatment side portion 5a of the heat shield 5 can be removed while the apparatus is in operation. Etching can be performed, and the operating rate of the device can be improved. In addition, since only the portion where the adhesion is strong can be replaced with a new one, it is possible to prolong the life without excessive etching of the other portions. Further, the heat shield efficiency can be improved by specifying the average diameter, the scattering coefficient and the density of the fine bubbles of the high purity quartz glass plate. In the embodiment described above, the heat shield 5 occupies 1/3 of the total height of the heat shield 5 and the non heat treated side 5 occupies the remaining 2/3.
Although the case of being composed of two groups b and b has been described, the present invention is not limited to this, and two groups occupying ½ of the total height or three groups occupying ⅓ of the total height or occupying appropriate heights. There may be four or more groups, and each group may be separably coupled.

FIG. 3 is a perspective view of a main part of a vertical heat treatment furnace showing another embodiment of the semiconductor heat treatment apparatus of the present invention. In this vertical heat treatment furnace, the heat shield 14 comprises six circular high-purity quartz glass plates 15 containing fine bubbles.
A plurality of high-purity silica glass columns 16 containing micro-bubbles are integrally connected at a required interval, and the density ρ is 1.9 <ρ ≦ 2.2 g / cm ³ , the non-heat-treated area side is 1.7. Different in two steps within the range of ≤ρ≤2.1 g / cm ³ , or the density ρ is 1.7≤ρ≤2.2 g / cm ³
In this range, the heat treatment region side is changed to a non-heat treatment region side so as to be reduced in multiple stages, and the density is reduced from the heat treatment region side to the non-heat treatment region side in at least two stages. Other configurations are shown in FIG.
The description is omitted because it is almost the same as the one described above.

The density ρ of the high-purity quartz glass plate 15 and the high-purity quartz glass column 16 on the heat treatment area side is 1.9 g / cm.
^When it is less than ³ , the strength is lowered, and it cannot withstand creep and thermal shock. When it exceeds 2.2 g / cm ³ , the heat shield efficiency is lowered. Preferably 2.0 ≦ ρ ≦ 2.1 g / cm
^{Is 3} . In addition, the high-purity quartz glass plate 1 on the non-heat treatment area side
5 and high-purity quartz glass column 16 have a density of 2.1 g /
If it exceeds cm ³ , the heat shield effect is significantly reduced, and 1.7 g /
If it is less than cm ³ , the strength is reduced and dust may be generated. Preferably, 1.8 ≦ ρ ≦ 2.0 g / cm ³ . The scattering coefficient, the number of sheets, the thickness, and the like of the high-purity quartz glass plate 15 are almost the same as in the case of the first embodiment, and thus the description thereof will be omitted.

In the vertical heat treatment furnace having the above-mentioned structure, the heat treatment area can be used as the heat shield 14 which is excellent in strength, and the non-heat treatment area can be used as the heat shield 14 which has a low dust generation and an excellent heat shield effect. It is possible to increase the heat shield efficiency of the entire body 14 and to have sufficient strength and low dust generation.

In the description of each of the embodiments of the present invention, the vertical heat treatment furnace is described as the semiconductor heat treatment apparatus, but the present invention is not limited to this and can be applied to a horizontal heat treatment furnace.

[0012]

EXAMPLES Next, examples of one embodiment of the present invention will be described together with comparative examples. First, in a vertical heat treatment furnace maintained at a furnace temperature of 1200 ° C., the average diameter of fine bubbles was 30 to 80 μm.
The thickness of one sheet is 4 mm, and the number of sheets is 9 sheets (3 + 3 + 3
Sheet), a three-division structure with a space of 25 mm, and a heat shield made of high-purity quartz glass plate with scattering coefficient and density as shown in Table 1 was placed in the furnace, and after the temperature in the furnace reached a predetermined temperature, When the temperature of the hearth after 60 minutes was measured, it was as shown in Table 1.

[0013]

[Table 1]

As shown in Table 1, it can be seen that the heat shielding effect is sharply reduced when the amount of microbubbles is small and the scattering coefficient is less than 200 m ^-1 . On the other hand, when the amount of fine bubbles is large and the scattering coefficient exceeds 1200 m ^-1 , the heat shielding effect is large, but the mechanical strength is small and dust is generated a lot, which is unsuitable for semiconductor heat treatment. Met. Therefore, the scattering coefficient is 200 to
It is preferably 1200 m ^-1 , more preferably,
It was found to be 300 to 1000 m ^-1 . Also, 10
We examined the thickness of a high-purity quartz glass plate (600 m ^-1 ) containing microbubbles at a furnace temperature of 00 ° C or higher, and measured the amount of heat shield per unit thickness, and as a result, the heat shield up to about 10 mm. It was found that the heat-shielding effect could not be expected so much even if the thickness was made thicker than that, but rather the heat capacity was adversely affected. On the other hand, when the thickness is less than 4 mm, the strength is insufficient. Therefore, the thickness per sheet is preferably 4 to 10 mm, more preferably 4 mm.
It was found to be ~ 7 mm. Furthermore, as a result of measuring all the high-purity quartz glass plates (600 m ^-1 , 4 mm) containing micro bubbles, the heat flux cannot be sufficiently shielded unless the number is 4 or more, and 13 It was found that even if the number of sheets is more than one, improvement of the heat shield effect cannot be expected, and the heat capacity is adversely affected. Therefore, it was found that the number of sheets is preferably 4 to 12, and more preferably 6 to 9.

Next, as the heat shield of the embodiment used in the vertical heat treatment furnace for 6-inch wafers, according to the specifications shown in Table 2, the heat treatment area side 1/3 portion of the total height and the remaining 2/3 portion can be separated. The heat shield with the integrated structure of the specifications shown in Table 2 was continuously used as a comparative example while the 1/3 part was removed and replaced with a new one every 20 times of continuous use. The temperature of was as shown in Table 3.

[0016]

[Table 2]

[0017]

[Table 3]

As shown in Table 3, in the case of this example, the temperature of the hearth portion became 120 ° C. after 20 uses, which was about 40 ° C. higher than the initial temperature (about 80 ° C.). However, the temperature of the hearth became 95 ° C by replacing the 1/3 portion where the adhesion was intense, and the temperature recovered by about 25 ° C. After that, the temperature of the hearth portion increased to 143 ° C. and increased by about 48 ° C. in the next 20 uses. Here, the temperature of the hearth was reduced to 1 by replacing the 1/3 part where the adhesion was intense again.
The temperature reached 05 ° C, and the temperature was recovered by about 38 ° C. Then, the temperature of the hearth portion became 155 ° C. in the next 20 uses.
On the other hand, in the case of the comparative example, the temperature of the hearth portion was 150 ° C. after 40 consecutive uses, and the temperature of the hearth portion was 172 ° C. after the next 20 consecutive uses. By the way, the upper limit temperature of the hearth is to prevent thermal deterioration of the packing of the flange,
160 ° C. Therefore, according to the present embodiment, the number of times of use capable of maintaining the heat shield performance can be increased by 50% as compared with the comparative example.

An example of another embodiment of the present invention will be described together with Comparative Examples 1 to 3. First, as heat shields used in a vertical heat treatment furnace for 6-inch wafers, six high-purity quartz glass plates containing microbubbles with a diameter of 200 mm and a thickness of 5 mm were used. The total height is 200 mm by stacking three pieces at equal intervals, and the density of the three high-purity quartz glass plates on the heat treatment area side and the high-purity quartz glass columns between them is 2.1 g / cm. ³ ,
An example in which the density of the three quartz glass plates and the remaining high-purity quartz glass columns on the non-heat-treated region side was 1.9 g / cm ³ was used as an example, and the overall density was 1.9 g / cm ³ , 2.1 g / cm ³ . cm ³ and 2.0 g / cm ³ were designated as Comparative Examples 1, 2 and 3. Then, the heat shields of Examples and Comparative Examples 1 to 3 were placed in a vertical heat treatment furnace and heat-treated at a maximum temperature of 1200 ° C. The heating / cooling rate at this time was 100 ° C./min, the isothermal temperature was 5 hours, and the heat shield had a cylindrical shape of 38 kg of transparent quartz glass corresponding to the weight of the 6-inch wafer and wafer boat. I put a weight on it. Table 4 shows the evaluation results of the heat shields after repeated heating and cooling of 50 times. The amount of deformation indicates how short the height has become as a whole.

[0020]

[Table 4]

As shown in Table 4, the results of Comparative Example 1 in which the overall density was 1.9 g / cm ³ with an emphasis on the heat shield efficiency, the hearth temperature was the lowest at 95 ° C. The good thermal efficiency was shown. However, the amount of deformation is as large as 1.2 mm, and it cannot be put to practical use as it is. on the other hand,
Contrary to Comparative Example 1, the result of Comparative Example 2 in which the entire density was 2.1 g / cm ³ with an emphasis on strength characteristics, the deformation amount was as small as 0.4 mm, but the temperature of the hearth was 160 ° C. it was high. This one has insufficient heat-shielding efficiency in practical use. Comparative Example 3
Is an intermediate density between Comparative Example 1 and Comparative Example 2.
The value of 0 g / cm ³ indicates that the temperature of the hearth is 110 ° C. and the amount of deformation is 0.8 mm, which is a relatively well-balanced characteristic. The results of the examples of Comparative Examples 1 to 3 are almost the same as those of Comparative Example 1 in which heat shielding efficiency is emphasized and Comparative Example 2 in which strength characteristics are emphasized. Further, compared with Comparative Example 3, the heat shield efficiency is almost the same, but the deformation amount is 60% smaller. Therefore, it can be seen that the heat shields of Examples are comprehensively excellent in heat shield efficiency and strength characteristics. The amount of dust generated almost corresponds to the degree of decrease in strength.

[0022]

As described above, according to the first semiconductor heat treatment apparatus of the present invention, it is possible to remove a portion having a strong adhesion and replace it with a new one, so that the heat shield during the operation of the apparatus can be prevented. The heat-treated side of the body can be etched to improve the availability of the device. or,
Since only the part where the adhesion is strong can be replaced with a new one, it is possible to prolong the life without overetching the other parts. Further, the heat shield efficiency can be improved by specifying the average diameter, the scattering coefficient and the density of the fine bubbles of the high purity quartz glass plate. Further, according to the second semiconductor heat treatment apparatus, the strength is secured on the heat treatment region side of the heat shield, while the heat shield efficiency is secured on the non-heat treatment region side while reducing the generation of dust. A heat shield having strength can be obtained, and the heat shield efficiency can be improved while reducing dust generation.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a vertical heat treatment furnace showing an embodiment of a semiconductor heat treatment apparatus of the present invention.

FIG. 2 is an exploded perspective view of essential parts of the vertical heat treatment furnace of FIG.

FIG. 3 is a perspective view of a main part of a vertical heat treatment furnace showing another embodiment of the semiconductor heat treatment apparatus of the present invention.

[Explanation of symbols]

 5 Heat Shield 5a Heat Treatment Side 5b Non-heat Treatment Side 8 High Purity Quartz Glass Plate 9 High Purity Quartz Glass Column 10 High Purity Quartz Glass Plate 11 High Purity Quartz Glass Column 12 Dowel Hole 13 Dowel 14 Heat Shield 15 High Purity Quartz Glass plate 16 High-purity quartz glass column

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/324 H01L 21/324 D

Claims (6)

[Claims] 1. A plurality of high-purity silica glass plates containing microbubbles are juxtaposed at intervals between the heat-treated region and the non-heat-treated region and are separably coupled to at least two groups. A semiconductor heat treatment apparatus characterized by: 2. The plurality of high-purity quartz glass plates have an average diameter of fine bubbles of 200 μm or less and a scattering coefficient of 200 to 1
2. The semiconductor heat treatment apparatus according to claim ¹ , wherein the density is 200 m ⁻¹ and the density ρ is 1.7 ≦ ρ ≦ 2.2 g / cm ³ . 3. The semiconductor heat treatment apparatus according to claim 1, wherein the plurality of high-purity quartz glass plates have a total number of 4 to 12 and a thickness of 4 to 10 mm. . 4. A plurality of high-purity silica glass plates containing micro-bubbles are arranged side by side with a space between the heat-treated region and the non-heat-treated region, and the density is increased from the heat-treated region side to the non-heat-treated region side. A semiconductor heat treatment apparatus characterized in that it is made different in at least two stages that are made smaller. Wherein said plurality of high-purity quartz glass plate, the density [rho heat treatment region side ^{1.9 <ρ ≦ 2.2g / cm 3} , the non-heat-treated region side 1.7 ≦ ρ ≦ 2.1g / cm ³ 5. The semiconductor heat treatment apparatus according to claim 4, wherein the heat treatment apparatus is different in two stages within the range. 6. The plurality of high-purity quartz glass plates are different in multiple steps so that the density ρ decreases in the range of 1.7 ≦ ρ ≦ 2.2 g / cm ³ from the heat treatment region side to the non-heat treatment region side. The semiconductor heat treatment apparatus according to claim 4, wherein the heat treatment apparatus is a semiconductor heat treatment apparatus.