JPH067238U - Semiconductor heat treatment equipment - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] The present invention forms a boat for processing semiconductor wafers by combining a high-purity synthetic quartz member and a natural quartz member having good heat resistance, and is used for wafers such as impurity diffusion. It is an object of the present invention to provide a semiconductor heat treatment apparatus having a wafer processing boat that has good processing conditions excluding elements that adversely affect the processing conditions. According to the invention, a supporting means 2 for forming a wafer contact portion where the impurities contained in the equipment used may be diffused during the heat treatment of the wafer to most adversely affect the electrical properties of the wafer, and the supporting means. A holding member 1 that allows a large number of wafers to be stacked and placed on each other and shares structural strength
It is proposed that the supporting means is made of high-purity synthetic quartz having a much smaller content of impurities, and the holding member is made of natural quartz having high heat resistance so as to be integrated with the supporting means.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a semiconductor heat treatment apparatus in which semiconductor wafers are stacked and held for heat treatment in a core tube, and more particularly to a vertical semiconductor heat treatment apparatus.

[0002]

[Prior art]

 Conventionally, a wafer processing boat, in which semiconductor wafers are stacked and arranged, can be housed in a core tube surrounded by heating means, and the semiconductor wafer mounted on the processing boat is heated to a predetermined temperature range by the heating means. A heat treatment apparatus for conducting various heat treatments such as oxidation, diffusion, vapor phase growth, and annealing of the semiconductor wafer surface area by flowing a reaction gas or an inert gas through the semiconductor wafer surface area under control is known. In order to save the installation area and to increase the diameter of the semiconductor wafer, a vertical heat treatment apparatus in which the core tube is erected vertically is frequently used in the apparatus. A wafer processing boat used in such a heat treatment apparatus is configured such that a large number of semiconductor wafers can be stacked and mounted at appropriate intervals in a wafer supporting groove formed on a plurality of holding members vertically standing on a base.

Such a wafer processing boat is used in a high temperature processing step of 100.degree. C. or higher by stacking a large number of semiconductor wafers stacked thereon. For example, a silicon wafer is processed into a semiconductor device. In this case, a natural quartz member is generally used as a constituent member of the wafer processing boat. This natural quartz member is a useful support member that can be easily made into complex shapes, has a relatively high purity, is relatively immune to the effects of pollutants, and can withstand most of the atmosphere in the processing stage. It is also chemically stable and has considerable dimensional stability even in the range of 1000 to 1300 ° C.

[0004]

[Problems to be solved by the device]

 However, when the above-mentioned natural quartz member is used as a holding member having the wafer supporting groove engraved therein, a natural stone which is a constituent member of the supporting member at a contact portion with the wafer in the wafer supporting groove during heat treatment of the semiconductor wafer. Impurities in the UK have diffused and have adversely affected wafer processing. In view of the above matters, it has been considered to use high-purity synthetic quartz for the holding member, but since the maximum operating temperature of high-purity synthetic quartz is as low as 950 ° C, the supporting member is bent during the heat treatment, and Was unusable.

The present invention has been made in view of the above technical problems, and a high-purity synthetic quartz member and a natural quartz member having good heat resistance are combined to form a boat for processing a semiconductor wafer, and impurities such as diffusion of impurities are formed. It is an object of the present invention to provide a semiconductor heat treatment apparatus having a wafer processing boat that has favorable processing conditions, excluding the elements that adversely affect the wafer processing conditions.

[0006]

[Means for Solving the Problems]

 In order to achieve the technical problem, the present invention considers the structure of a wafer processing boat housed in the semiconductor heat treatment apparatus, and a plurality of wafer holding members are erected on a base and the members are attached to the member. The conventional structure in which a large number of wafers are stacked and held by forming wafer support grooves at appropriate intervals is divided into two parts, and the constituent members are changed to compliment the length. That is, during the heat treatment of the wafer, the supporting means for forming the wafer contact portion where the impurities contained in the equipment used may diffuse to most adversely affect the electrical properties of the wafer, and a large number of supporting means are provided. The wafers are divided into a holding member that can be stacked and placed to share structural strength, and high-purity synthetic quartz with a much lower impurity content is used for the supporting means. It is proposed that high natural quartz is used and integrated with the supporting means. Therefore, the buckling stress and bending stress due to the total load of the stacked semiconductor wafers applied during the heat treatment of the supporting means are shared by the holding member made of natural quartz which is integral with it. The contact support with the wafer is shared by the support means consisting of high-purity synthetic quartz, and the contamination of the wafer during heat treatment is minimized.

Further, it has been proposed that the holding member has a structure in which a heat-resistant core material made of a structural ceramic is inserted and filled in the hollow portion of the holding member to be internally sealed, and a large number of wafers having a large diameter are prepared. Make sure that it has sufficient strength for stacking and that it will not deform even when used continuously at high temperatures.

Further, the entire surface of the holding member in which the heat-resistant core material made of the structural ceramic is encapsulated is covered with synthetic quartz to form a triple structure, and a wafer supporting groove is formed in the outermost synthetic quartz coating layer. The object of the present invention may be achieved by a method in which the supporting means and the holding member are integrated and the processing cost is relatively low.

[0009]

[Action]

 According to the above technical means, the semiconductor wafers are provided on a plurality of holding members vertically standing around the semicircular portion of the holding space of the semiconductor wafer, and directly contact and support the wafers for stacking the wafers in the holding space. Since high-purity synthetic quartz is used as the wafer supporting means, it is possible to minimize contamination of the wafer by impurities during the heat treatment of the wafer. Further, since the supporting means made of synthetic quartz is integrated with the holding means made of natural quartz, when a large number of wafers are stacked and heat-treated, the buckling and bending moment due to the total load of the loaded wafers are caused by the supporting means. The bending of the boat can be easily prevented by being applied to the holding member via.

Preferably, the holding member made of natural quartz is formed into a hollow shape, and the hollow portion thereof has a heat-resistant core of a structural ceramic, which is a sintered body of high-purity fine powder such as SiC, Si, or Si3N4. Since the material is inserted, filled, sealed, and built-in, the holding member can be used as a structural member to further improve heat resistance and fatigue resistance, and can be used for larger wafer diameters. It can handle the increase in the number of sheets.

A coating layer made of high-purity synthetic quartz is provided as an outer layer of the holding member made of natural quartz in which the heat-resistant core material of the structural ceramic is built-in, and the wafer is supported on the outermost synthetic quartz coating layer. When the groove is provided to form the supporting means, it is possible to reduce the manufacturing cost.

[0012]

【Example】

 Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, etc. of the components described in this embodiment are not intended to limit the scope of the present invention, but merely illustrative examples. Nothing more. FIG. 1 is a perspective view of a first embodiment of a wafer processing boat housed in a core tube, and FIG. 2 is a perspective view showing details of a holding member and supporting means of the first embodiment of FIG. .

As shown in the figure, in the wafer processing boat, a plurality of columnar holding members 1 of natural quartz (electro fused natural quartz) are erected vertically on the peripheral edge of one side of the substrate 3, and the semiconductor holding semiconductor is installed from the opposite side. The wafer 7 is accessible. The disk-shaped structure 4 is fixed to the upper end face of the upper surface to form a processing boat. Wafers of the plurality of holding members 1 facing the holding space are provided with a supporting means 2 made of high-purity synthetic quartz having a rectangular cross-section and integrated with the holding member 1 so that a large number of semiconductor wafers are substantially horizontal. Alternatively, the wafer support grooves 5 are engraved at appropriate intervals so that the wafer insertion tips are slightly lowered and the wafers are stacked and placed. The high-purity synthetic quartz is formed by hydrolyzing silicon tetrachloride in an oxyhydrogen flame, and as shown in the comparison table of purity analysis values with electrofused natural quartz in the lower column, high-purity synthetic quartz is It shows that the content of impurities is very low. Element Na K Li Al Cu Ni Natural quartz 0.2 0.3 0.7 20 0.02 0.2 Synthetic quartz <0.01 <0.05 <0.05 0.1 <0.01 <0.05 (ppm) Usually, high-purity synthetic quartz has lower heat resistance than natural quartz at 1100 ℃. If it is used continuously with, it will deform. For this reason, in this embodiment, natural quartz having high heat resistance and high-purity synthetic quartz are integrated, and the synthetic quartz and the natural quartz are separately used depending on the place of use. That is, high-purity synthetic quartz is used for the supporting means 2 for supporting and supporting the semiconductor wafer so as to minimize contamination on the wafer, and to prevent buckling and bending moment due to the total weight of the supporting wafer. The holding member 1 made of natural quartz is adapted.

FIG. 3 is a perspective view showing details of the integrated wafer supporting means and holding member of the second embodiment according to the present invention. As shown in the figure, a hollow natural quartz holding member 1a is prepared in place of the holding member 1 shown in FIG. 1, and the hollow portion is a sintered body of high-purity fine powder such as SiC, Si, or Si3N4. A heat-resistant core material 6 made of a rod-shaped structure ceramic is inserted, and it is filled up tightly so as not to create a gap in the heat treatment process. Further, in order to prevent the explosion due to expansion of air due to heating during the heat treatment, the inside is in a vacuum state. Sealed. On the outside of the holding member 1a, similarly to FIG. 1, high-purity synthetic quartz support means 2 having wafer supporting grooves 5 formed at appropriate intervals are provided integrally with the holding member 1a. Regarding the structural ceramic SiC, the heat resistance strength is kept at a high value up to 1400 ° C, it is chemically stable, has no fatigue phenomenon, has a small expansion coefficient, and has high dimensional stability. The use of the core material prevents deformation of the wafer processing boat due to the weight of the wafer processing boat and the wafer load during continuous use at high temperature.

FIG. 4 is a perspective view showing the details of the integrated wafer supporting means and holding member of the third embodiment according to the present invention. As shown in the drawing, a holding member 1b made of natural quartz and a supporting means 2a made of high-purity synthetic quartz have an integrated double tube structure, and the hollow portion of the holding member 1b is made of a rod-shaped structure ceramic as in FIG. The heat-resistant core material 6 is inserted and filled and vacuum-sealed. The supporting means 2a has a wafer supporting groove 5 formed at appropriate intervals. In this case, the workability is good, but the contact area of the wafer support groove with the wafer is large, and the problem of non-uniform heat history within the wafer surface occurs due to the effect of radiant heat from the boat. This causes variations in the thermal oxide film and the impurity diffusion depth inside.

Although the above embodiments have dealt only with the vertical boat, the present invention is applicable not only to the vertical boat but also to a horizontal boat, and also applicable to a heat treatment apparatus other than the boat. Is.

[0017]

[Effect of device]

 As described above, according to the present invention, when the semiconductor wafer is heat-treated, the high-purity synthetic quartz is used as the supporting means of the wafer processing boat that directly contacts and supports the wafer. Contamination is eliminated and wafer processing conditions can be greatly improved. In addition, since heat-resistant natural quartz that is integrated with the synthetic quartz support means is used as the holding member of the wafer processing boat, and the strength necessary for holding the wafer is shared, the support means is heat resistant. The use of high-purity synthetic quartz, which has no properties, comes out. Further, since the holding member made of natural quartz has a structure in which, for example, a ceramic rod-shaped core material obtained by sintering high-purity fine powder is built-in and sealed, it is possible to cope with an increase in the size of the wafer processing boat and to prevent deformation and bending during high-temperature continuous heat treatment. You can prevent it from happening. The outermost layer is made of high-purity synthetic quartz, the middle layer is made of natural quartz, and the structure is such that a rod-shaped heat-resistant core material made of a structural ceramic material is inserted and sealed inside the double tube structure, and the outermost layer is a wafer. Since the supporting grooves are formed at appropriate intervals to form the wafer supporting means, the contamination of impurities on the wafer can be reduced at a low processing cost. It has various remarkable effects.

[Brief description of drawings]

FIG. 1 is a perspective view showing a wafer processing boat according to an embodiment of the present invention.

FIG. 2 is a perspective view showing details of a holding member and supporting means of the embodiment of FIG.

FIG. 3 is a perspective view showing a wafer processing boat according to a second embodiment, showing details of a portion where a wafer supporting means and a holding member are integrated.

FIG. 4 is a perspective view showing a wafer processing boat according to a third embodiment and showing details of a portion where a wafer supporting means and a holding member are integrated.

[Explanation of symbols]

 1, 1a, 1b Holding member 2, 2a Supporting means 3 Base 4 Disc-shaped structure 5 Wafer supporting groove 6 Rod-shaped heat-resistant core material 7 Semiconductor wafer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidetoshi Nagata No. 3 No. 3 Kayaya-cho, Takefu-shi, Fukui Prefecture Fukui Shin-Etsu Quartz Co., Ltd. (72) Kazuki Ofuji No. 3 Kayoya-cho, Takefu-shi, Fukui Prefecture Address 4 Fukui Shin-Etsu Quartz Co., Ltd. (72) Creator Ryoichi Yamamoto No. 3 Kaguya-cho, Takefu-shi, Fukui Prefecture No. 1 Number 4 Fukui Shin-Etsu Quartz Co., Ltd. (72) Creator Hiroko Ueda No. 3 Kayutani-cho, Takefu-shi, Fukui Prefecture Address 4 Fukui Shin-Etsu Quartz in stock company

Claims (3)

[Scope of utility model registration request] 1. A semiconductor heat treatment apparatus in which semiconductor wafers are stacked and held for heat treatment in a core tube, and a support means made of high-purity synthetic quartz in which wafer support grooves for holding and holding the semiconductor wafers are stacked and held at appropriate intervals. And a holding member made of a plurality of natural quartz, which is integrally formed with the supporting means so as to form a holding space for the wafer and is erected on a substrate. 2. The semiconductor heat treatment apparatus according to claim 1, wherein a ceramic heat resistant core material is enclosed in the holding member. 3. The supporting means is composed of a cylindrical covering body which covers the entire surface of a holding member for encapsulating the heat resistant core material, and wafer supporting grooves formed at appropriate intervals are provided on the covering body. The semiconductor heat treatment apparatus according to claim 2, which is configured.