JP2002542621A - Silicon fixture for wafer processing and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] A silicon tower that removably supports multiple silicon wafers during heat treatment. One preferred embodiment of the tower includes four legs fixed at its ends to two bases. A plurality of slots can be formed in the legs to slidably insert and support the wafer. The legs are preferably rounded wedges, preferably including a curved front face having a small radius with slots formed therein and a curved rear face having a substantially larger radius. Preferably, the legs are machined from round bars of untreated polysilicon. The base may be untreated poly or single crystal silicon. By providing energy, various attachment methods can be used to secure the legs to the base, including methods for fusing the legs to the base.

Description

DETAILED DESCRIPTION OF THE INVENTION

BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates generally to fixtures used to support wafers in the manufacture of semiconductor integrated circuits, and more particularly to silicon fixtures that support wafers.

[0002] 2. TECHNICAL BACKGROUND As the commercial production of silicon wafers evolves, increasingly larger wafers are processed in increasingly larger batches, while the individual dimensions are reduced to 0.1 mm.
It has become smaller than 18 μm. As processing becomes more demanding, the demands on the performance of processing equipment and the performance of wafer handling and transfer mechanisms needed to move, transport, and hold wafers during processing are becoming increasingly stringent. It has become to. These requirements include maintaining a constant temperature,
And contamination by impurities or particles.

[0003] During many chemical and thermal processing operations, wafers are often subjected to various processing steps, particularly annealing, dopant diffusion, or chemical vapor deposition, which are performed simultaneously on many wafers. Must be held in the correct position.
For this purpose, relatively large and complex structures such as "boats" or "towers" are typically used. U.S. Pat. No. 5,492,229 to Tanaka et al. Discloses an example of such a structure. Tanaka et al. Disclose a vertical boat for holding a plurality of semiconductor wafers. The boat includes two end members and a plurality of support members. In one embodiment, the support member is formed from a vertically cut pipe member to provide a long plate member having a quarter arc cross section. In another embodiment, the support member is formed from a vertically cut pipe member to provide a long plate member having a half arc cross section. Tanaka et al. Mention quartz glass, silicon carbide, carbon, single crystal silicon, polycrystalline silicon, and silicon-impregnated silicon carbide as materials that can be used for the boat. When manufactured from quartz glass, the various elements must be fused together. Otherwise, "the device can be assembled in a predetermined manner."

US Pat. No. 5,534,074 to Koons also relates to a vertical boat for holding semiconductor wafers. The boat includes a plurality of rods having slots formed along its length. The slots are intended to reduce shadowing on wafers placed in the boat during processing. Although the rod is cylindrical and specified to be manufactured from fused quartz, any well-known material suitable for holding a wafer can be used. U.S. Pat. No. 4,872,554 to Cuernemoen discloses a reinforced carrier for silicon wafers and the like. The carrier includes side elements consisting of annular rails with teeth projecting therefrom for holding the wafer at regular intervals. The rail is made of plastic and may include a rigid insert for reinforcement. The teeth can be formed integrally with the rail or welded to the rail.

US Pat. No. 5,752,609 to Kato et al. Relates to a wafer boat that includes a plurality of rods arranged to support a ring member. The plurality of wafer supporting pieces are connected to the ring member and include a protrusion having a corner for making contact with the wafer.
Kato et al. Also discloses a wafer boat that includes a plurality of cylindrical quartz rods having a wafer support recess therein. The theoretical advantages of pure silicon structures are well known. Conventional towers and boats are usually made of quartz or silicon carbide, but these materials contain contaminants and become unstable at higher temperatures. Fabricating the wafer holding structure from the same material as the wafer itself reduces the possibility of contamination and deformation to a minimum. Silicon structures react with processing temperatures, conditions and chemistries in much the same way as wafers, significantly improving the overall useful life of the structures.

[0006] Unfortunately, the standard assembly of silicon structures in a "predetermined manner" disclosed by Tanaka et al. Has not made pure silicon widely accepted as a material for structures such as boats and towers. This is one of the reasons. Single crystal silicon, polycrystalline silicon, and unprocessed polycrystal are difficult to process, so the structures described in Tanaka et al. Patents have been developed, but when single crystal silicon is selected as the material Considering the above, there is no description about the connection between the support member and the target member, and the above-described method of manufacturing the support structure only includes cutting out the extruded annular member. Such support structures are inherently less stable than support structures made from older, more easily processed materials, such as quartz or silicon carbide.

[0007] Similarly, Koons, Cuernemoen and Kato et al. Do not address the particular problem of providing a robust and reliable wafer support structure that reduces shadowing and contamination. While the protrusions and slots described in the above patents are effective to some extent, they are not suitable for fabrication from materials such as silicon and also provide a stable and accurate wafer support. Requires a relatively large cross-sectional area. Silicon has been found to be very brittle and difficult to melt. Therefore, well-known silicon structures are considered delicate at best, and very fragile at worst. Therefore, the silicon structure has not been widely accepted commercially.

Furthermore, due to the crystal structure of single crystal silicon, a blank extruded from crystalline silicon has a distinct “grain” that runs substantially vertically through the blank. The silicon blank is cut transversely across the grain, usually with a thread saw. Unfortunately, when used for vertical cutting, conventional cutting techniques tend to split the silicon blank along the grains, thereby ruining the blank. Single crystal silicon structure members and polycrystalline silicon for use in the manufacture of semiconductor wafers and the like that can eliminate the disadvantages of known silicon structures while retaining the advantages of silicon as a structure material It can be seen that a method for manufacturing a structural member is desired.

Czochralski (CZ) single crystal silicon is of a type used as a wafer in a semiconductor integrated circuit, and has a horizontal length essentially elongated as a large ingot from molten silicon. It consists of 200 mm and 300 mm silicon single crystals. Czochralski polycrystalline silicon, often called quasi-single-crystal silicon, has virtually the same local structure as single-crystal silicon, but is made of individual crystals. The crystallites have a size on the order of 1 mm to more than 100 mm and are separated by grain boundaries. Such Czochralski polysilicon is considered conventional polysilicon in terms of structural members. Whether Czochralski silicon grows in single-crystal or polycrystalline form depends largely on the rate of extraction. Czochralski silicon may grow with 1 ppm of heavy metal impurities, while carbon and nitrogen may also be present at concentrations of 1 to 7 ppm, while oxygen may be grown at a concentration of 10 to 25 ppm. Exists. Crystallites usually have orientations that are very similar to each other. Further, polysilicon is often grown as a thin layer in silicon integrated circuits by chemical vapor deposition, but such films cannot be directly applied to the present invention.

[0010] Untreated polysilicon (hereinafter untreated poly) is used within the semiconductor industry.
Because of this is a special type of polysilicon that is widely manufactured. Unprocessed poly
Thermochemistry using various silanes as precursors to aggregate on heated seed rods
Forming a relatively large ingot (with a maximum diameter of about 15 cm) by vapor deposition (CVD)
Formed. Such precursor is SiH₄, SiClH₃, SiCl₂H ₂ , SiCl₃H, and SiCl₄including. Among these compounds, SiHCl ₃ H is the one most commonly used in commerce, but in float zone deposition.
In some cases, monosilane (SiH₄)
In some cases. Untreated poly is 10^-12cm^-3Or less impurity concentration
Grows with a very high degree of purity. The usual criteria is that untreated poly is 1 ppt (acid
Impurity levels of all possible contaminants, including sulfur, 1x10^-12)
This is a level that includes pure substances. With some variation, the untreated poly is 10 ppt
It has the following impurity levels: This is at least 1 ppm of heavy metals and up to 2 ppm
Czochralski polysilico containing various impurities of dissolved gas of 5 ppm or more
In contrast to Untreated poly can be easily crushed commercially.
It is manufactured to have high internal stress. Semiconductor silicon wafers are usually
Grows by the Czochralski method, but in this case, the polysilicon is crushed.
And then a bit of 1416 ° C, the melting point of silicon at atmospheric pressure.
At a temperature near the top, perhaps with the intentionally introduced dopant material,
It is. Single crystals aggregate on small seed crystals placed on the surface of the melt and
Crystal ingots are withdrawn very slowly from the melt.

Whether silicon by the Czochralski method becomes a single crystal or a polycrystal depends on whether
Highly dependent on its pulling rate, crystallites tend to grow large at random sizes. Untreated poly, on the other hand, tends to agglomerate from the hot seed rod and form crystalline arms that protrude radially from the rod. To our knowledge, unprocessed poly has never been used in silicon fixtures to support wafers during semiconductor processing. Thus, it can be seen that there is a need for a robust and reliable support member for a wafer processing fixture that reduces shadowing and contamination while accurately holding the wafer in a stable state.

SUMMARY OF THE INVENTION The present invention includes a silicon wafer processing fixture. The fixture includes a uniformly elongated silicon support member with a mounting element extending outwardly from an end thereof. The fixture also includes a substantially flat silicon base. The base includes a mounting element receiving portion for securely mounting the mounting element of the support member therein. In the case of the first embodiment, at least a part of the fixture is made of untreated polysilicon. In one more specific embodiment, the elongate member is machined from raw polysilicon and the integral base is single crystal silicon. In another embodiment, the base is composed of several parts, and these parts and the elongated members are all formed from untreated polysilicon.

The present invention provides a method for manufacturing an elongated structural member from a single blank of a crystalline material. The blank has a predetermined length, width and depth. A first generally flat cut is formed in the blank, the cut extending along substantially the entire length of the blank and for a distance substantially less than the entire width of the blank. At least one additional cut is formed in the blank, the additional cut being the first cut.
The blank is cut into two parts, extending in the same plane as the cut.

Forming the at least one additional cut may include forming a plurality of additional cuts. In some embodiments, the number of additional cuts is at least three. The cut can be made by a rotating saw with a blade having a diamond coated cut surface. When the saw operates, the blade speed is in the range of 50 to 50,000 rpm, but is preferably about 4,000 rpm. The blank of crystalline material can be supplied as a single blank of silicon material. The method of the present invention can be performed with a monocrystalline silicon material or a polycrystalline silicon material.

In some embodiments, the blank may be provided as a substantially cylindrical blank, ie, an ingot. The steps of forming a first substantially flat cut and forming at least one additional cut are performed iteratively on each of the two sections to form four sections from the original cylinder. And can be repeated iteratively to form eight parts from the original cylinder. Each of the eight sections has a substantially wedge-shaped cross section.

The present invention provides a method for securing a first silicon member to a second silicon member to form at least a portion of a silicon wafer processing fixture, as well as the silicon wafer processing fixture itself. Is disclosed. The method includes providing an outwardly extending attachment member to the first silicon member. A second silicon member is provided, at least in part, with a mounting element receiving portion surrounding the mounting member. Thereafter, the mounting element is securely fixed in the mounting element receiving part.

The present invention provides a method for manufacturing a support member for a wafer processing fixture. In a first step of the method, a basic form of the elongated support member is formed. The basic mold has a substantially wedge-shaped cross section and angular edges. Next, the edge of the base of the support member is machined to form a substantially arcuate edge instead of a square edge. A plurality of wafer holding slots are formed along one surface of the support member prototype.

The basic form of the support member may include a front surface and a rear surface, wherein at least one angular edge is present on each surface. Machining the edges of the base of the support member may include reducing the edges of each side from 0.25 inches (6.3 mm) to 5.25 inches (133
. This can be done by machining to a radius in the range of 3 mm). In some embodiments, at least one angular edge of the rear surface can be machined to a radius of about 1.5 inches (38 mm), and at least one angular edge of the front surface can be machined to about 0.1 mm. It can be machined to a radius of 35 inches (8.9 mm). Conveniently, all other corners of the support member have a smaller radius than the radius of the front surface.

At least one mounting structure may be formed on at least one end of the support member prototype. The mounting member is configured so that the support member can be easily mounted on the substantially flat base member. In some embodiments, the mounting structure can be provided as a set of cylindrical pegs, each extending from each end of the base of the support member. The basic form of the elongate support member can be made from an inert crystalline material such as polycrystalline silicon or monocrystalline silicon.

The step of forming a plurality of wafer holding slots along one surface of the support member prototype may be performed to form a plurality of cuts substantially perpendicular to a longitudinal axis of the support member prototype. The cut can extend the depth of the base of the support member by a suitable distance and can be formed by a rotating saw with a blade having a diamond coated surface. The wafer holding slot may be formed perpendicular to the front surface of the support member prototype.

The present invention also discloses a support member for a wafer processing fixture. The support member is 1
The set may include an elongated body portion having opposite ends, an arcuate front surface having a first radius of curvature, and an arcuate rear surface having a second radius of curvature. The first radius of curvature can be significantly smaller than the second radius of curvature. A plurality of mutually parallel wafer holding slots are formed on the front surface of the body portion.

In certain embodiments, a set of mounting structures can extend from each end of the support member. The mounting element is substantially cylindrical and the mounting element receiving portion is formed as a cylindrical bore having a diameter and length corresponding to the diameter and length of the mounting element. However, other shapes such as blades are possible. The first and second silicon members, including the mounting member, can be formed from single crystal silicon, polycrystalline silicon, or untreated polysilicon.

According to some methods, embodiments, the step of securely securing the mounting element includes forming a first lateral bore in the mounting element and a second lateral bore in the mounting element receiving portion.
Can be implemented by forming a lateral bore. The first and second lateral bores are coaxial with each other and can accommodate locating pins. When the first and second lateral bores are coaxially aligned with each other, the locating pins are secured within the first and second lateral bores. The length of the pin can be slightly longer than the combined length of the first and second bores, and the pin can be secured in the following manner. First, the locating pin is inserted into the alignment bore such that a portion of the locating pin extends outwardly from the outer limits of the first and second bores. Next, the extension of the locating pin is machined until it is flush with the outer limits of the first and second bores. Alternatively, the outer diameter of the locating pin may be substantially equal to the inner diameter of the first and second bores. In this case, the pins can be fixed in the following manner. First, the locating pins are frozen at cryogenic temperatures, causing the locating pins to shrink. The locating pin is then inserted into the aligned bore while maintaining the bore at ambient or higher temperature. Thereafter, the temperature of the positioning pin is returned to the ambient temperature and expanded.

In another fixing step, energy can be supplied to at least one of the mounting element and the mounting element receiving portion to fuse the mounting element to the mounting element receiving portion. In one embodiment, an access hole is provided in the mounting element receiving portion of the second silicon member. Laser energy is supplied from the access hole for tack welding the mounting element and the mounting element receiving portion. Alternatively, the mounting element and the mounting element receiving portion can be approximately the same size. Laser energy can be provided to an area adjacent both the mounting element and the mounting element receiving portion.

Further, in the case of another embodiment, a peripheral convex portion can be provided at the end portion of the first silicon member. A peripheral recess may be provided at the end edge of the second silicon member. Laser energy is supplied such that the peripheral protrusions of the first silicon member melt into the peripheral recesses of the second silicon member. For about 3 minutes or until the melt of silicon fills the peripheral recess, the protrusion is heated to 1,416 degrees, which is the melting point of silicon, preferably,
Laser energy is provided to heat to about 1,450 degrees. Further, in another embodiment, the step of securely securing the mounting element within the mounting element receiving portion includes the steps of:
The method includes a step of applying an adhesive having a high adhesive strength and no contamination. The mounting element is substantially cylindrical and the mounting element receiving portion is formed as a cylindrical bore having a diameter and length corresponding to the diameter and length of the mounting element. The first and second silicon members can be formed from single crystal silicon, polycrystalline silicon, or unprocessed polysilicon.

Detailed Description of the Preferred Embodiment FIG. 1 shows a silicon wafer processing fixture 10. The silicon wafer processing fixture 10 includes a plurality of uniformly elongated support members 12 (hereinafter referred to as legs) secured between a set of generally flat base members 14, hereinafter referred to as a base. A plurality of slots 16 are typically formed in each leg 12 at equal intervals and are used to support a plurality of wafers in the assembled tower 10. The tower is typically installed semi-permanently in a semiconductor processing reactor configured for one of many different processes. Multiple wafers are placed in tower 10 and subsequently processed simultaneously. This process may be moderately temperature in the range of 400-700 ° C., or 1,000-1 °, depending, to some extent, on whether chemical vapor deposition, annealing, or thermal diffusion is performed.
, 380 ° C.

The tower 10 in the figure has four legs 12.
It may be a book or a single book. The most typical method is to place the wafer in a slot 16 by an automated robot that supports the wafer on a paddle that moves laterally to the axis of the tower 10 while the legs 12 hold the wafer firmly. In this method, a plurality of legs are attached to the base 14 within a range slightly wider than 180 degrees on the outer periphery of the base 14 so that the base 14 can be inserted into the base 14.

The legs 12 and the base 14 can be made in any suitable manner from an inert crystalline material such as single crystal silicon or polycrystalline silicon. Preferably, legs 12 are formed from untreated poly because of the low level of impurities. This is because the legs 12 directly contact the wafer. Also, for many applications, the legs 12 need to be relatively long, and long untreated poly is readily available. However, base 14 is easily formed from single crystal silicon. The diameter of the base 14, which is conveniently formed substantially circular, must be greater than the diameter of the wafer to be processed. At present, most wafers have a diameter of 200 mm, but 300 mm wafers have also been manufactured. 300mm or 200
Even large unprocessed poly ingots larger than mm are not readily available, but ultra-large CZ crystalline ingots are available for special applications. The manufacture of the legs is divided into two main steps. That is, (1) a step of forming a wedge-shaped basic mold, and (2) a step of machining the above-mentioned basic mold into a leg having a novel cross section.

A basic mold is made by machining from the cylindrical blank 20 of FIG. Blank 2
0 is substantially cylindrical, its length is L and its diameter is D. However, the invention can be applied to any suitable blank of almost any shape. The blank 20 can be made from a crystalline material such as monocrystalline silicon or polycrystalline silicon, but currently an untreated poly blank is preferred. Silicon blanks are widely available commercially. One suitable silicon blank supplier is SILICON CRYSTALS INC. The blank can be manufactured to any size, but is typically 4 inches (10 cm) long.
) To 80 inches (200 cm), 0.75 inches (2 cm) to 36 inches (diameter)
91 cm).

As shown schematically in FIG. 3, the method according to one aspect of the invention uses a series of progressive cuts along the longitudinal axis of the blank 20 to cut the blank into small pieces. In step 22, a first substantially planar cut _{C 1,} is formed in the blank 20. As shown in the side sectional view of FIG. 4 and the axial sectional view of FIG.
Cut C ₁ in the substantially the entire length L of the blank 20, also the total width of the blank 20 (in this case, the diameter D) extending a substantial distance shorter than. In step 24 of FIG. 3, additional cut _{C 2} is formed in the blank 20. Side cross-sectional view of FIG. 6, and as shown in axial cross-section view of FIG. 7, the cut C ₂ is
Extending the first same plane as the cut C _1.

If the diameter of the blank 20 is relatively small, two cuts are sufficient to divide the blank into two parts H ₁ and H ₂ , as shown in FIG. Instead, to completely separate the _two parts H ₁ , H ₂ of FIG. 8, step 26 of FIG.
As shown, there (N-2) number of additional cuts, even if made of _{C 3} need _{C N.} For a normal blank having a diameter of 3 inches (76 mm), three cuts have been found to give good results. However, high pressure fluid cutting has been found to be effective when cutting the entire blank 20 in one step. In addition, if the surface finish can be compromised, use a diamond blade.
Cutting by multiple steps is effective.

The cutting of the blank 20 can be performed by any appropriate technique. At this time, it is believed that the cutting can be effectively performed using a rotating saw, such as the M4K34F21G model from MK. This saw includes, for example, Natio
nal Diamond Lab part number 10125D22, or 10
A blade with a diamond at the tip, such as 125D100, can be equipped. During the cutting of the blank, the saw can be operated at a speed of 50-50,000 rpm. A speed of about 4,000 rpm has been found to be particularly effective. Although the use of a rotating saw is effective, it should be understood that the rotating saw is merely exemplary. Other cutting devices can be used to achieve acceptable results. Examples of such devices include, but are not limited to, saws using diamondless blades, lasers, wire saws, polishing saws, reciprocating saws, and polishing fluid cutting devices.

In many cases, the manufacture of the structural support member is facilitated by the step of providing half of the blank of FIG. 8, a small piece smaller than H ₁ , H ₂ . In such a case, in step 26 of FIG. 3, to make _four pieces Q _{1 to} Q ₄ from the original blank 20 as shown in FIG. 9, or as shown in FIG. to make a ₁ to E _8, for each piece of two halves, can be iteratively performing progressive cutting steps of the above. The resulting base leg 30, shown as an orthographic view in FIG. 11, has a vertex angle of 45 degrees. The depth of the cut in step 26 becomes shallower, resulting in a smaller value of N. The above procedure can be modified as needed to produce a solid segment with a selected value of apex angle less than 90 degrees, but for the least shadowing, 45 degrees or less. The following angles are preferred.

The basic leg mold 30 of FIG. 11 has a substantially wedge-shaped cross section. The base leg 30 has a front surface 32 that includes a sharp edge 34 at the front of the wedge. The base leg 30 has an arcuate rear surface 36 including a set of angular edges 38 at the rear of the wedge, and two flat sides that are mutually inclined. FIGS. 12 to 14 show the steps of building up a basic support member mold 30 into a completed support member. As shown in FIG. 12, the first step is to have angular edges 34,
Machining the front and rear surfaces of the base leg 30 (shown in dashed lines) to remove 38 and thereby form a rounded trapezoidal member 40. The surface can be machined to a radius between 0.25 (6 mm) and 5.25 inches (133 mm). In the illustrated example, the front surface of trapezoidal member 40 is machined to a radius of about 0.35 inches (9 mm) and the rear surface is larger, about 1.5 inches (38 m).
machined to a radius of m). A preferred ratio of the rear radius to the front radius is at least three, more preferably four. The advantage of a significantly different ratio is that the formation of wafer support slots on the side with the smaller radius results in less shadowing of the wafer occurring during processing, while the larger radius farther from the wafer has a higher mechanical stiffness. Is to give.

The rounded wedge of FIG. 12 also has two advantages. The first advantage is that material wasted during machining can be minimized. A second advantage is that there is no sharper (smaller radius) shape than the front surface where the slot is formed. As a result, there are no sharp corners that tend to scrape off the accumulated deposits and increase the number of particles. That is, the rounded shape increases the adhesion to any film deposited on the fixture during wafer processing. Other embodiments have a rounded wedge shape at the front and a rounded rectangular shape at the back of the leg, with all surfaces equal to or less than the radius of the front corner where the slot is formed. Joins a bend with a larger radius.

The radius in FIG. 12 can be machined using any machine tool. Examples of such machine tools include a plated diamond router manufactured by National Diamond Lab or a resin bonded diamond wheel with a water swivel. Such machine tools are available at National
It has been found that excellent results are achieved when used with a bit, such as a custom resin bonded diamond wheel from Diamond Lab.

The basic leg mold 40 is machined to form a plurality of wafer holding slots 16 as shown in FIG. Slot 16 is used to form slotted legs 42.
Here, it is formed along one side surface of the basic leg mold 40 which is the front surface. The slots 16 are parallel to each other and are substantially perpendicular to the longitudinal axis A of the base leg 36 of FIG.
The slot 16 extends along a substantial portion of the length L, except for the end length E. The slot 16 may extend longer or shorter than half the depth D of the support member prototype, depending on the particular application. Although the illustrated slot 16 has two flat, parallel surfaces, more complex shapes may be advantageous, and such complex shapes may be easily formed by standard machining techniques. it can.

[0038] Slot 16 can be formed by any suitable diamond tool, such as a commercially available diamond saw blade. Examples of suitable cutting devices include:
There is a 3-4 inch resin bonded wheel manufactured by National Diamond Lab. Such a slotter is available from National Diamond La.
It is particularly effective when used with a blade having a diamond coated cut surface, such as a 16-400 grain blade from Company b. Slot 1
During the formation of 6, the slotter can be operated at speeds in the range of 5-125,000 rpm. A speed of about 4500 rpm has been found to be particularly effective. Although it is advantageous to use the specified cutting device, it should be understood that the cutting device is merely exemplary. Other cutting devices can be used to achieve acceptable results. Examples of such devices include, but are not limited to, a slotter using a diamondless blade, a laser, and a polishing fluid cutting device.

There are two different designs for attaching the legs 12 to the base 14. FIG.
As shown in the side elevational view of FIG.
Except for the slot 16, it has a cross section that extends to its rounded wedge-shaped end 44. Complementary, blind, round wedge-shaped holes 46 are machined into the two opposing bases 14 to accommodate the rounded wedge-shaped ends of the legs 42. By doing so, there is an advantage that the rotational rigidity is increased.

Alternatively, as shown in the side elevational view of FIG. 15 and the orthographic view of FIG. 16, at least one mounting structure 50 on each end 52 of the leg 54 with a stake. Are formed by machining. The mounting structure 50 is shown as a set of opposed cylindrical pegs. The pegs are formed by machining the ends of the support member base 30. This machining can be performed by any suitable cutting mechanism. Examples of suitable cutting devices include NOVA, JET, or PRESTO
There are vertical or horizontal milling machines or CNC machines from manufacturers such as the company. The mounting structure 50 is adapted and assembled to facilitate mounting of the legs 54 to the substantially flat base 14 having a corresponding blind cylindrical mortise 56. For example, the mounting structure 50 may have other shapes, such as a blade shape corresponding to the base groove shape. It should be understood that the legs can be attached to the base in any suitable manner.

The finished product of the leg 22 can be made to any desired size. For example, the legs in the figure having a wedge angle of about 22 degrees 60 seconds can be formed from a base leg mold having a width of about 0.475 inches (12 mm) and a length of about 45 inches (114 mm). . The slot 16 in the illustrated embodiment has a depth of about 0.25 inches (6 mm) and extends a distance of about 43 inches (109 cm) along the entire length of the leg 22.
This distance can be longer. The cylindrical pegs 50 that make up the mounting structure of FIG. 16 extend about 0.6 inches (15 mm) from the ends of the legs 54 to about 0 inches.
. It has a diameter of 4 inches (10 mm).

FIGS. 17 to 23 show various techniques for attaching the legs to the base. In each of these examples, as shown in FIG.
The silicon member 60 includes a mounting member or tenon 62 extending outward. However, it should be understood that the tenon 62 may not be used and instead an extension of the first silicon member 60 may be used, as shown in FIG. The second silicon member 64, which is a base member in this figure, includes a tenon 66. Mortise hole 66
2 at least partially.

In some embodiments, a first lateral bore 70 is drilled into the tenon 62 and a second lateral bore 72 is secured to secure the tenon 62 in the tenon 66. A portion of the second silicon member 64 adjacent to the tenon 66 is drilled. The first and second lateral bores 70, 72 are sized to accommodate the locating pins 74 when the bores are coaxially aligned with one another. The locating pins 74 may be connected to the first and second lateral bores 70,
72. In the case of the embodiment of FIG.
4 is slightly longer than the sum of the lengths of the first and second bores 70,72. The locating pin 74 is inserted into the aligned bores 70, 72 such that a portion 76 of the locating pin 74 (shown in dashed lines) extends outward from an outer limit 78 of the second bore 74. Thereafter, the portion 76 extending toward the outside of the positioning pin 74 is
It is machined to be flush with the outer limit 78 of the second bore 72.

FIG. 18 illustrates another fixation technique. The locating pins 80 are provided in the first and second bores 82, 8 in a portion of the second silicon member 64 adjacent to the tenon 62 and the tenon 66.
The inner diameter _{D 2} of 4, with outer diameter approximately equal to _{D 1.} In this example, the locating pins 80 are cooled to -100 ° C. at cryogenic temperatures, so that the locating pins 80 contract. The cooled locating pins 80 are inserted into the alignment bores 82, 84 with the bore maintained at ambient temperature. Thereafter, the temperature of the positioning pins 80 returns to the ambient temperature, and the positioning pins 80 expand. The diameter of the locating pin 80 shrinks by about 0.001% when cooled at cryogenic temperatures. Instead of a technique using locating pins, energy can be supplied to the mortise, mortise or both to fuse the mortise and tenon.

FIG. 19 shows an example of the above technique. In the case of this example, the access hole 88
The second silicon member 64 is drilled so as to reach the bottom of the mortise 66.
Laser energy is supplied through access hole 88 to perform tack weld W between tenon 62 and tenon 66. Pulse width 30 ns and pulse period 0
. It has been found that irradiating with laser energy from a 001 second 250 W CO ₂ laser for 1 to 5 minutes can provide advantageous results. It can be used Coherent Inc. of CO ₂ any suitable laser energy source such as a laser.

FIG. 20 shows a cross-sectional view of another assembling method. In the case of this embodiment, the tenon
2 and tenon 66 extend through the second silicon member with approximately the same extent. To form a tack weld that can extend around all or a portion of the interface area A1, in the area A1 adjacent to the interface between the tenon 66 and the tenon 66,
Can supply laser energy. Any suitable laser energy source can be used.

In the case of the other examples shown in FIGS. 21 and 22, the tenon 62 extends through the second silicon member 64 and includes a peripheral protrusion 90 at its end 92. The second silicon member 64 includes a peripheral inclined portion 94 surrounding the outer end of the mortise 66. Thermal energy is supplied to melt the peripheral projections 90 of the first silicon member 60 into the peripheral slopes 94 of the second silicon member 64, thereby fusing the tenon 62 with the tenon 66. Any suitable heat source can be used to provide heat. It has been found that one heat source that can be used to advantage is the heat generated by the laser energy. The laser energy heats the protrusion 90 for about 3 minutes to a temperature above the melting point of silicon, 1416 ° C., preferably to a temperature of about 1450 ° C. Used until part 94 is satisfied.

FIG. 23 illustrates another fixation technique. In the case of this example, the tenon 62
The step of firmly fixing the includes the step of applying an adhesive to the area A ₂ that extends between the tenon 62 and mortise 66 in the axial direction. Typically, high temperature, non-staining adhesives must be used to avoid contamination associated with the use of the adhesive. The mounting element of FIGS. 17 to 23 is substantially cylindrical and comprises a mounting element receiving part formed as a cylindrical bore. However, it should be understood that these shapes are merely exemplary, and that any suitable cooperating shape may be selected for the mounting elements and associated retaining portions.

The various fixing methods described above can be used not only to manufacture wafer towers, but also for other structures where two or more pieces of silicon must be tightly assembled. In order to form the tower 10 of FIG.
Applies between two and two bases 14. However, still other fastening methods can be used. Preferably, the number of legs 12 is preferably four, but three is sufficient and two is sufficient. Mortise is drilled in the two bases. Preferably, they are opened at equal angular positions at an angle slightly wider than 180 degrees. Since the slot 16 allows for a wider gap, the robot blade is preferably inserted into the tower 10 horizontally by sliding the slot 16 without touching the sides of the slot 16 during insertion. The support can be maintained in a stable state on the bottom surface of the slot 16.

In the case of FIG. 1, the base 14 has a continuous, symmetrical circular shape, but the base may still be substantially circular, but may have a more complex shape. For example, the base can include an outer flat and an inner opening.
Further, preferably, the integral base is made from a single crystal of silicon, but it is also possible to secure the parts together to form a multi-part silicon base. In this case, it is more preferable to use untreated poly for the base. In the case of the above embodiment, the slot is formed in a wedge-shaped leg. However, the invention is not so limited. The legs and wafer support may be otherwise shaped, such as a silicon arm projecting from a cylindrical or rectangular leg and supporting the wafer at its distal end.

Using the present invention, structural members of single crystal silicon, polycrystalline silicon, or untreated polysilicon can be manufactured for use in the manufacture of semiconductor wafers and the like. , Can be applied to any large and / or complex fixtures or parts thereof for use in processing silicon wafers. The use of components using the structural members of the present invention can avoid deformation during high temperature processes. Since the raw material is of the same quality as the wafer material, particle contamination and "crystal slip" inherent in known materials such as silicon carbide can be virtually avoided. Furthermore, there is no shadowing. Because the raw material copies the physical properties and important constants of the processed wafer on a one-to-one basis. Single crystal fixtures and portions thereof provide tolerances and expected life that cannot be achieved with commonly used materials such as quartz or silicon carbide. Using the present invention, advantageous silicon components and fixtures can be manufactured when the manufacturing process shifts to 300 mm and larger wafer diameters. Having described the invention with reference to specific embodiments, those skilled in the art will appreciate that
It will be understood that the invention can be modified in various ways without departing from the spirit and scope of the invention.

[Brief description of the drawings]

FIG. 1 is an orthographic view of a silicon wafer processing fixture incorporating the principles of the present invention.

FIG. 2 is a blank for use in the method of the present invention.

FIG. 3 is a flowchart illustrating the steps of an embodiment of the present invention.

FIG. 4 is a side sectional view of the blank during the cutting process.

FIG. 5 is an axial sectional view of the blank corresponding to FIG. 4;

FIG. 6 is a side sectional view of the blank during the cutting process.

FIG. 7 is an axial sectional view of the blank corresponding to FIG. 6;

FIG. 8 is a diagram showing each step included in the method of the present invention.

FIG. 9 is a diagram showing each step included in the method of the present invention.

FIG. 10 is a diagram showing each step included in the method of the present invention.

FIG. 11 is a view showing a basic type of a support member used in the method of the present invention.

FIG. 12 is an end elevational view of the basic mold of the support member in the first stage of the manufacturing process.

FIG. 13 is a side elevational view of a basic form of the support member at a subsequent stage in the manufacturing process.

FIG. 14 is an orthographic view of a first embodiment of a combination of a leg and a base.

FIG. 15 is a side elevational view of the base of the support member at another stage of the manufacturing process.

FIG. 16 is an orthographic view of a second embodiment of the combination of a leg and a base.

FIG. 17 is a cross-sectional view showing a technique for fixing components of the silicon wafer processing fixture.

FIG. 18 is a cross-sectional view showing a technique for fixing components of a silicon wafer processing fixture.

FIG. 19 is a cross-sectional view showing a technique for fixing components of the silicon wafer processing fixture.

FIG. 20 is a cross-sectional view showing a technique for fixing components of the silicon wafer processing fixture.

FIG. 21 is a cross-sectional view showing a technique for fixing components of a silicon wafer processing fixture.

FIG. 22 is a cross-sectional view showing a technique for fixing components of a silicon wafer processing fixture.

FIG. 23 is a cross-sectional view showing a technique for fixing components of the silicon wafer processing fixture.

[Procedural Amendment] Submission of translation of Article 34 Amendment

[Submission date] June 5, 2001 (2001.6.5)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claims

[Correction method] Change

[Contents of correction]

[Claims]

24. A method according to claim 20, wherein supplying the energy step, in order to melt the portion extending toward the outside, including the step of performing laser irradiation to a temperature of 1416 ° C. than Features method.

25. The method of claim 20, wherein the outwardly extending portion of the first silicon member is a generally cylindrical outwardly extending mounting element, and wherein the mounting element receiving portion comprises A method as claimed in any preceding claim, comprising a cylindrical bore formed in said second silicon member to accommodate an outwardly extending portion.

26. The method according to claim 20, characterized in that said first silicon member has a non-circular shape, and extends toward the outer portion and the attachment element receiving portion having said non-circular shape And how.

────────────────────────────────────────────────── ─── Continued on the front page (31) Priority claim number 09 / 292,496 (32) Priority date April 15, 1999 (April 15, 1999) (33) Priority claim country United States (US) ( 81) Designated countries EP (AT, BE, CH, CY, DE, DK, ES, FI, FR, GB, GR, IE, IT, LU, MC, NL, PT, SE), CN, JP, KR , SG (72) Inventor Robert Davis 94002, California, Belmont Suit 30 Village Court 2200 F-term (reference) 5F031 CA02 HA62 HA63 HA64 5F045 BB14 EM08 EM09

Claims (28)

[Claims] 1. A silicon tower for supporting a plurality of wafers, comprising: two bases composed of silicon; and a first plurality of legs composed of untreated polysilicon. A silicon tower having legs fixed to said two bases at two ends thereof for removably supporting a plurality of wafers. 2. The tower according to claim 1, wherein each of the legs has a plurality of slots formed on a first surface thereof, the slots supporting the plurality of wafers, and A tower slidably insertable into said slot. 3. The tower of claim 2, wherein each of the legs is formed according to a cross-sectional leg shape including the first surface having a curved shape with a first radius. The tower also has a portion that does not have a radius of curvature less than the first radius. 4. The tower of claim 3, wherein the leg shape includes a second surface facing the first surface and having a curved shape having a second radius greater than the first radius. A tower characterized by the following. 5. The tower according to claim 4, further comprising a slot formed in the first surface. 6. The tower according to claim 3, wherein said leg shape includes a flat second surface facing said first surface. 7. The tower according to claim 3, further comprising a cylindrical hole formed in the base and having the shape of the leg for accommodating the leg. 8. The tower of claim 3, wherein the legs are non-circular, each leg having a cylindrical peg formed on two ends thereof. A tower having a cylindrical hole formed in said base for receiving said peg. 9. The tower according to claim 3, wherein the legs have a non-circular shape. 10. The tower according to claim 9, further comprising a hole having the non-circular shape formed in the base for receiving the leg. 11. The tower of claim 1, wherein each of the bases comprises unprocessed polysilicon. 12. The tower according to claim 1, wherein each of the bases is made of silicon grown by a Czochralski method. 13. A silicon tower for supporting a plurality of wafers, each comprising a plurality of parts secured together, two bases composed of raw poly, and a base made of raw polysilicon. A first plurality of legs, each of said legs being fixed to said two bases at two ends thereof to removably support a plurality of wafers. 14. The silicon tower according to claim 13, wherein each of the legs has a plurality of slots formed on one surface thereof, the slots supporting the plurality of wafers, A tower wherein a wafer is slidably insertable into said slot. 15. A support member for a wafer processing fixture, comprising: an arcuate front surface having a first radius of curvature; and a flat or first surface opposite to the front surface.
An elongated silicon body portion having a cross-sectional body shape including a back surface having a second radius of curvature greater than the radius of curvature, wherein no portion of the body shape has a radius of curvature smaller than the first radius of curvature; A support member comprising a plurality of mutually parallel wafer holding slots formed in said front surface of said body portion. 16. The support member according to claim 15, wherein the rear surface is curved, and a ratio of the second radius of curvature to the first radius of curvature is at least three. 17. The support member according to claim 15, wherein the rear surface is flat. 18. The support member according to claim 15, wherein the silicon member is made of untreated poly. 19. The support member according to claim 15, wherein the silicon member is made of single crystal silicon. 20. A method for securing a first silicon member to a second silicon member to form at least a portion of a silicon wafer processing fixture, the method comprising: Providing an outwardly extending portion; providing the second silicon member with a mounting element receiving portion that at least partially surrounds the outwardly extending portion; Attaching to the mounting element receiving portion; and firmly fixing the outwardly extending portion in the mounting element receiving portion, wherein the fixing step extends outwardly to the mounting element receiving portion. At least one of the outwardly extending portion and the mounting element receiving portion to fuse the portions. Method characterized by comprising the step of supplying energy whereas the. 21. The method of claim 20, wherein the step of providing energy comprises the step of providing laser energy. 22. The method according to claim 20, wherein the mounting element receiving portion comprises a ramp around a bore for receiving the outwardly extending portion. 23. The mounting element receiving portion of claim 20, wherein the outwardly extending portion melts and fuses with the mounting element receiving portion when receiving the energy supply. A portion extending beyond. 24. The method of claim 20, wherein the first and second silicon members are selected from the group consisting of single crystal Czochralski grown silicon, polycrystalline Czochralski grown silicon, and unprocessed polysilicon. A method characterized by forming from: 25. The method of claim 24, wherein at least one of said first and second silicon members comprises untreated polysilicon. 26. The method according to claim 20, wherein the step of providing energy includes the step of laser irradiation to a temperature above 1416 ° C. to melt the outwardly extending portion. Features method. 27. The method of claim 20, wherein the outwardly extending portion of the first silicon member is a generally cylindrical outwardly extending mounting element, and wherein the mounting element receiving portion includes the mounting element receiving portion. A method as claimed in any preceding claim, comprising a cylindrical bore formed in said second silicon member to accommodate an outwardly extending portion. 28. The method of claim 20, wherein the first silicon member has a non-circular shape, and wherein the outwardly extending portion and the mounting element receiving portion have the non-circular shape. And how.