JP2008300425A - Bonding method of silicon crystals, and silicon crystal product - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To fix a plurality of silicon crystals with required thermal resistance and strength without using a mechanical means made of silicon. <P>SOLUTION: As shown in A, a recess 1a is provided in a rod-shaped silicon crystal 1 and a projection 2a is provided on a rod-shaped silicon crystal 2. A recess 2b is provided at the tip of the projection 2a. After a bonding material 3 is put into the recess 2b as shown in B, the rod-shaped silicon crystals 1 and 2 are fitted together as shown in C. In this state, both crystals are put into an electric furnace, and the temperature and the atmosphere suitable for the bonding material 3 are achieved. When predetermined conditions are achieved, the bonding material 3 is melted to infiltrate into a clearance 4 between the surfaces to be bonded as shown in D. The rod-shaped silicon crystals 1 and 2 are firmly bonded together by cooling them. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a silicon crystal (single crystal, polycrystal) bonding method and a silicon crystal product bonded by the method. More specifically, the present invention relates to effective silicon parts and silicon jigs used in semiconductor manufacturing equipment. The present invention relates to a silicon crystal bonding method and a silicon crystal product that realize assembly and reduction of the number of parts.

  In a semiconductor manufacturing apparatus, a high-purity silicon wafer is accommodated therein, and advanced semiconductor elements are manufactured through various processes such as heat treatment, film formation, chemical corrosion, and exposure. Among these, in a thermal diffusion process for doping impurities into a silicon wafer and a CVD process for forming an oxide film and a nitride film, a boat and a stage for storing silicon wafers having diameters of 200 mm and 300 mm are required. Conventionally, quartz glass (SiO2) and silicon carbide (SiC) have been used for these storage components, but these components are moved by being exposed to high temperatures or exposed to special gases during the manufacture of semiconductor devices. Ingredients become fine particles and scatter around. However, the performance and precision of semiconductor devices are increasing year by year, and contamination from quartz glass and silicon carbide particles scattered during the process causes the quality of the device to become unstable, leading to a decrease in product yield. is there. For this reason, there has recently been a movement to use boat and stage parts with silicon crystals made of the same material as silicon wafers. That is, if the silicon crystal can cover the parts in the semiconductor manufacturing apparatus, the impurity contamination in the process is greatly reduced, and an ideal semiconductor device can be manufactured.

  At present, assembling of quartz glass boats and stages, which are mainly used in semiconductor manufacturing equipment, is performed by a method of fusion bonding with an oxygen / hydrogen gas burner. An oxide such as quartz glass and a glassy material has long been melted and bonded using a gas burner in the air.

  However, silicon is crystalline and cannot be melt-bonded at its melting point of 1414 ° C. Moreover, since the surface is oxidized at temperatures above 1000 ° C, it cannot be handled in air. Therefore, in order to fix and bond the silicon parts in the semiconductor manufacturing apparatus, a method other than fusion bonding must be taken under a specific clean gas atmosphere. Also, materials that cause impurity contamination in the semiconductor manufacturing process cannot be used, and bonding and fixing that can withstand the temperature (400 ° C. to 1100 ° C.) during heat treatment and film formation of the silicon wafer are required. Therefore, at present, silicon parts are fixed using silicon bolts, nuts, and wedges (see Patent Document 1).

  However, fixing with silicon mechanical means (silicon bolts, nuts, wedges, and other fixed parts) is a: Bolts and wedges loosen due to the temperature cycle during use, so adjustment is required for each operation. There are problems such as b: extra parts such as bolts and wedges for fixing are required, c: repair is difficult when damaged or worn, d: man-hours for assembling, and cost for processing fixed parts I have a point.

Japanese Patent Laid-Open No. 7-9285

  The present invention has been made to solve the above-described conventional problems, and its purpose is to fix a plurality of silicon crystals with required heat resistance and strength without using silicon mechanical means. It is to be.

The invention of claim 1 includes a step of disposing a bonding material that fuses with silicon at a temperature lower than the melting point of silicon between a plurality of silicon crystals to be bonded, and the bonding material and the silicon crystal at the melting point of the bonding material. This is a method for bonding silicon crystals, which includes the step of heating to a temperature lower than the melting point of silicon and the step of cooling and solidifying the heated bonding material and silicon crystal.
According to a second aspect of the present invention, in the method for bonding silicon crystals according to the first aspect, the bonding material is germanium.
According to a third aspect of the present invention, in the method for bonding silicon crystals according to the first aspect, the bonding material is a silicon-germanium alloy.
According to a fourth aspect of the present invention, in the method for bonding silicon crystals according to the first aspect, the bonding material is germanium dioxide.
According to a fifth aspect of the present invention, in the method for bonding silicon crystals according to any one of the first to fourth aspects, the shape of the bonding material is a powder shape, a paste shape, a thin plate shape, a granular shape, a rod shape, or a ring shape. It is characterized by.
A sixth aspect of the present invention is the method for bonding silicon crystals according to any one of the first to fifth aspects, wherein one of the plurality of crystals has a recess for containing the bonding material.
The invention of claim 7 is the method for bonding silicon crystals according to claim 2 or 3, wherein the bonding material and the silicon crystals are heated in an atmosphere of an inert gas, a hydrogen gas, or a mixed gas thereof. .
According to an eighth aspect of the present invention, in the method for bonding silicon crystals according to the fourth aspect, the bonding material and the silicon crystals are heated in an atmosphere of oxygen gas, water vapor, or a mixed gas thereof.
The invention of claim 9 is a silicon crystal product having a plurality of silicon crystals joined by the method of any one of claims 1-8.

(Function)
According to the present invention, a bonding material that fuses with silicon at a temperature lower than the melting point of silicon is disposed between a plurality of silicon crystals to be bonded, and the bonding material and the silicon crystal are equal to or higher than the melting point of the bonding material and silicon. The bonding material and silicon are fused together by heating to a temperature lower than the melting point, and then cooled and solidified to bond a plurality of silicon crystals.

  According to the present invention, it is possible to directly join a plurality of silicon crystals without using fixing parts such as silicon bolts, nuts and wedges. For this reason, it becomes possible to convert all the silicon parts, silicon jigs, etc. used for a semiconductor manufacturing apparatus etc. into a silicon crystal member, and the price of them can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The following three items are listed as problems to be solved when the silicon parts used in the semiconductor manufacturing apparatus are fixed without using the silicon-made fixing parts.
The first problem is to secure the heat resistant temperature of the joint at about 1100 ° C.
The second problem is to prevent impurity contamination caused by a material other than silicon used for the joint portion. Naturally, this bonding material is required to have a heat resistance of about 1100 ° C. What is selected as the bonding material is the most important issue.
The subject of the third section is the setting of the atmosphere when bonding silicon crystals. As the temperature rises, silicon easily reacts with component gases in the air such as chlorine, bromine, etc., oxygen, nitrogen, water vapor, etc., and its surface state is converted to other silicon compounds, which is a factor that hinders bonding between silicon. Become. Therefore, it is important what kind of component the atmosphere at the time of joining can be joined easily.

  In the present embodiment, in order to solve the first problem, three types of materials, germanium, silicon-germanium alloy, and germanium dioxide, are selected as materials used for bonding.

First, the joining of germanium and silicon-germanium alloy will be described.
In general, silicon is known to easily react with all metal elements at high temperatures to form an alloy. Of these combinations, silicon and germanium are the only combinations that are mixed in a solid solution type that can be alloyed in any ratio.

  Fig. 1 shows the phase diagram of germanium-silicon. From this, the gradient from the liquid phase region to the liquid phase / solid phase mixed region to the solid phase region has a gentle gradient from 100% germanium melting point 936 ° C to 100% silicon melting point 1414 ° C. It turns out that it is changing. Therefore, if germanium is sandwiched between silicon crystals and the melting point of germanium is raised to 936 ° C. or higher as it is, the sandwiched germanium will melt and alloy with silicon, and if the temperature is lowered, the composition distribution according to the phase diagram of FIG. It solidifies. That is, a eutectic mixture of germanium and silicon is formed and solidifies.

  For example, when the bonding temperature is raised to 1050 ° C., the liquid germanium dissolves silicon and becomes a composition having a silicon amount of about 12 at% shown at point a in FIG. After a while, the solid phase and the liquid phase coexist in the range from point a to point b in the bonding layer, and solidification starts at a silicon concentration of 35 at% at point b, and at a constant concentration due to a temperature drop in the direction of point c. Solidify. Actually, there is a concentration distribution toward the silicon portion at the junction due to the amount of germanium and the standing time. When a silicon-germanium alloy is used as the bonding material, the melting temperature may be set according to the composition of the alloy used according to FIG.

  Thus, there are several advantages in self-alloying bonding in which silicon on both sides to be bonded itself is bonded to germanium. For one thing, the thermal expansion coefficients of silicon and germanium are different, and if they are raised to about 1000 ° C, thermal stress is applied to the joint and the cause of damage increases, but this joint becomes an intermediate component between silicon and germanium. As a result, the thermal stress is relieved and the mechanical strength is prevented from decreasing. A further advantage is due to the property that by increasing the bonding temperature, the silicon concentration of the bonding layer increases according to the phase diagram, with the solidification temperature increasing towards the melting point of silicon 1414 ° C. accordingly. This characteristic has the advantage that the heat resistance temperature of the silicon component can be controlled between about 1000 ° C. and 1300 ° C. by changing the bonding processing temperature.

  A description will be given of silicon crystal bonding using germanium dioxide, which is the third bonding material. It is known that germanium dioxide (GeO2) has a melting point of 1116 ° C. and becomes a glass when solidified, like quartz glass (silicon dioxide: SiO2). Further, since germanium dioxide is easily reduced to metal germanium when heated to about 1000 ° C. in hydrogen gas, it must be heated in an oxidizing atmosphere in order to maintain stable germanium dioxide. On the other hand, when silicon is heated in the presence of oxygen or water vapor, the surface is oxidized and a silicon dioxide thin film is easily formed. Although silicon dioxide and germanium dioxide are not completely solid solution types like germanium-silicon on the phase diagram, this bonding method utilizes the fact that they are oxides and vitrified and fused together. That is, a eutectic mixture of germanium dioxide and silicon dioxide is formed and solidified.

  Next, a solution method for impurity contamination when a material other than silicon is used for the joint portion, which is the second problem, will be described. A silicon semiconductor element exhibits a special function by adding a trace amount of a specific element to an ultra-high purity silicon single crystal. Therefore, avoiding impurity contamination in the device manufacturing process is the most important proposition. For example, the most important element of impurity contamination is the periodic table of elements that immediately affects the electrical characteristics of the device, with trivalent aluminum (Al), gallium (Ga), indium (In), and pentavalent phosphorus. Elements such as (P), arsenic (As), and antimony (Sb). Conversely, relatively safe elements are tetravalent carbon (C), germanium (Ge), and tin (Sn) in the periodic table. Since these are tetravalent in the same group as silicon, they are electrically neutral and have the least influence on the electrical operation of the device. Among these, germanium is particularly used as a material for early semiconductors, and recently, high-performance semiconductors composed of silicon / germanium mixed crystals have been put into practical use. Therefore, germanium is an element having the least influence on the silicon semiconductor element, and it can be said that the discovery of germanium or a silicon-germanium alloy in the joining of the parts for semiconductor manufacturing apparatus in the present invention is the best choice.

  Further, when germanium dioxide is used as the bonding material, if the fine powder is generated in the semiconductor manufacturing process, there is a concern that the same contamination as when quartz glass parts or jigs are used. However, in the case of quartz glass parts and jigs, the whole is made of quartz glass, but in the case of silicon crystal bonding, the whole is silicon and only the bonding portion is germanium dioxide. In addition, since the volume and surface area of the joint portion are less than one thousandth of the whole and there are almost no exposed portions, contamination by germanium dioxide is kept to a minimum. In consideration of this, it can be expected that the influence of the germanium dioxide bonding material on the silicon semiconductor element is less likely to cause impurity contamination next to germanium and silicon-germanium alloy.

Next, a solution for keeping the surfaces suitable for bonding at the time of silicon crystal bonding, which is the third problem, will be described.
First, when using germanium and a silicon-germanium alloy as a bonding material, it is necessary to take a process that does not oxidize the bonding surface of the silicon crystal or to select an atmospheric gas. In particular, silicon begins to oxidize from around 500 ° C. in the presence of water vapor and from around 1000 ° C. in an oxygen atmosphere, and the silicon crystal surface is covered with a stable oxide film, and silicon cannot be bonded to each other. Therefore, in order to avoid the formation of these oxide films, the inside of the joining component storage container of the joining electric furnace is kept at a high vacuum from room temperature to about 400 ° C. using a vacuum pump. Thereafter, a high purity inert gas, a high purity hydrogen gas or a mixed gas thereof is introduced to a pressure of 1 atm, and the temperature is raised from about 400 ° C. to a bonding temperature of 1000 ° C. or higher while these gases are constantly flowing. In this way, the formation of an oxide film on the silicon surface can be minimized. In particular, when a reducing atmosphere is formed with high-purity hydrogen gas, formation of germanium oxide in the bonding material can be suppressed, and silicon crystal bonding using a bonding material of germanium or a silicon-germanium alloy can be effectively performed.

  On the other hand, when germanium dioxide is used for the bonding material, it is necessary to intentionally oxidize the bonding surface of the silicon crystal. Therefore, in this case, it is necessary to maintain a high-purity oxygen atmosphere and to maintain the temperature at a temperature higher than the melting point of germanium dioxide of 1116 ° C. and about 1150 ° C. to 1200 ° C. In the process of rising to this temperature, an oxide film is formed on the bonding surface of the silicon crystal, and when it reaches 1116 ° C. or higher, the melted germanium dioxide gets wet into the bonding surface and enters. Thereafter, when the temperature is lowered, the bonding surface is solidified as an ultrathin germanium dioxide glass, and both silicon crystals are firmly bonded via germanium dioxide bonded to the surface silicon dioxide.

Next, the shapes of the three types of bonding materials will be described.
The portion where the silicon crystal is bonded has different aspects such as the shape, positional relationship, force distribution method, and accuracy of the silicon component. Therefore, the shape of the bonding material used therein is powdery, pasty, thin plate, granular, spherical, rod-shaped, ring-shaped, etc., and it is effective to use a shape suitable for the application.

  Germanium, silicon-germanium alloy, and germanium dioxide powders are commercially available, and may be used as they are. In order to obtain a paste, a commercially available powder may be pulverized to about 1 micron or less, and a small amount of an organic solvent such as methanol may be added thereto to make a paste. Further, in order to obtain a thin plate shape, a granular shape, a spherical shape, a rod shape, and a ring shape of these bonding materials, in general, an ingot of each material is made, and a cutting, polishing, and the like are performed from this. However, this method has a lot of waste of materials and requires a lot of processing, and it is difficult to adopt it in terms of cost. Therefore, the present inventors possess a technology “shaping crystallization technology” that makes an inorganic crystal / glass material into a free shape as in the case of casting. (Patent No. 2947529: Manufacturing method and apparatus for shaped crystal) By using this technology, three types of joining materials can be easily created in the form of thin plates, granules, spheres, rods, and rings. Since all can be used, the cost is reduced, which seems to be the most suitable method for joining materials.

Hereinafter, a method for bonding silicon crystals having various shapes will be described in detail.
FIG. 2 is a diagram for explaining a method of joining rod-like silicon crystals together. Here, A is a perspective view, and B to D are cross-sectional views cut along a vertical plane passing through the axis of the rod-like silicon crystal. As shown in A and B, one bar-shaped silicon crystal 1 is provided with a recess 1a, and the other bar-shaped silicon crystal 2 is provided with a protrusion 2a. Further, a recess 2b for receiving the bonding material 3 is provided at the tip of the protrusion 2a. The surface (inner surface) of the recess 1a and the surface (outer surface) of the protrusion 2a serve as a bonding surface, and the bonding material 3 is disposed in the vicinity of the bonding surface.

  After the bonding material 3 is put into the recess 2b as shown in B, the rod-like silicon crystals 1 and 2 are fitted together as shown in C. While maintaining this state, the sample is placed in an electric furnace to have a temperature and atmosphere suitable for the bonding material 3. When the predetermined condition is reached, the bonding material 3 melts and enters the gap 4 on the bonding surface as indicated by D. By cooling from this state, the rod-like silicon crystals 1 and 2 are firmly joined. Note that, here, a rod-like silicon crystal having a circular cross section is shown, but the same bonding can be performed in a square, a triangle, or other shapes.

  FIG. 3 is a diagram for explaining an example of a method for joining plate-like silicon crystals to the upper and lower ends of a rod-like silicon crystal. Here, A is a plan view of a plate-like crystal bonded to the upper end, and B is a cross-sectional view of a state in which the rod-like crystal is fitted in the plate-like crystal, cut along a vertical plane including the axis of the rod-like crystal.

  As shown in A and B, the plate-like crystal 11 joined to the upper end is provided with a hole 11b for fitting the rod-like crystal 13 and a small-diameter hole 11a communicating above the center of the hole 11b. Similarly, a hole (not shown) for fitting the rod-like crystal 13 is provided in the plate-like crystal 12 joined to the lower end. At the lower end of the rod-shaped crystal 13, a recess 13 a for inserting the bonding material 14 is provided.

  As shown to B, the joining material 14 is put in the hollow 13a, and it fits into the plate-shaped crystal 12 and fixes. Further, the plate-like crystal 11 is fitted into the upper end of the rod-like crystal 13, and the bonding material 14 is put into the hole 11a at the upper end. While maintaining this state, the furnace is put in an electric furnace, set to a temperature and atmosphere suitable for the bonding material 14, and when a predetermined condition is reached, the bonding material 14 melts and enters the gap between the bonding surfaces. By cooling from this state, the rod-like silicon crystal 13 and the plate-like silicon crystals 11 and 12 are firmly joined. In this case, the cross-sectional shape of the rod-like crystal 13 is not limited to a circle, but the same bonding can be performed with a square, a triangle, or other shapes. The planar shape of the plate crystals 11 and 12 is not limited to a rectangle, but may be a circle, a triangle, or other shapes.

  FIG. 4 is a diagram for explaining another example of a method for bonding plate-like silicon crystals to upper and lower ends of a rod-like silicon crystal. Here, A is a plan view of a plate-like crystal bonded to the upper end, and B is a cross-sectional view of a state in which the rod-like crystal is fitted in the plate-like crystal, cut along a vertical plane including the axis of the rod-like crystal.

  As shown in A, the plate-like crystal 11 joined to the upper end is provided with a hole 21b for fitting the rod-like crystal 23 and four small-diameter holes 21a communicating above the peripheral edge of the hole 21b. Similarly, a hole (not shown) for fitting the rod-like crystal 23 and an annular recess 22a are provided in the plate-like crystal 22 joined to the lower end. It can be said that the annular recess 22a is obtained by expanding the diameter of the opening of the hole for fitting the rod-like crystal 13 therein.

  As shown in B, the bonding material 24 is put in the recess 22a, and the rod-like crystal 23 is fitted and fixed. Further, the plate-like crystal 21 is fitted into the upper end of the rod-like crystal 23, and the bonding material 24 is put into the depression 21a at the upper end. While maintaining this state, it is put in an electric furnace, and is brought to a temperature and atmosphere suitable for the bonding material 24. When a predetermined condition is reached, the bonding material 24 melts and enters the gap between the bonding surfaces. By cooling from this state, the rod-like silicon crystal 23 and the plate-like silicon crystals 21 and 22 are firmly joined. Here, the cross-sectional shape of the rod-like crystal 23 is not limited to a circle, but the same bonding can be performed with a square, a triangle, or other shapes. The planar shape of the plate crystals 22 and 22 is not limited to a rectangle, but may be a circle, a triangle, or other shapes.

  FIG. 5 is a view for explaining a method of joining the plate-like silicon crystals with the rod-like silicon crystals lying sideways. The left end of the rod-like silicon crystal 33 is fixed while penetrating the plate-like silicon crystal 31, and the right end is fixed in the plate-like silicon crystal 32. In this figure, A is a cross-sectional view of the state in which the plate-like silicon crystals 31 and 32 are fitted in the rod-like silicon crystal 33, cut along a vertical plane passing through the center portion in the thickness direction of the plate-like silicon crystal 31. 3 is a cross-sectional view taken along a vertical plane including an axis of a rod-shaped silicon crystal 33. FIG.

  A through-hole (not shown) for fitting the rod-like silicon crystal 33 is formed in the plate-like crystal 31, and the bonding material 34 is placed on the center of the through-hole in the depth direction (thickness direction of the plate-like crystal 31). Open a small hole 31a for insertion. On the other hand, the plate-like crystal 32 is formed with a non-penetrating hole for fitting the rod-like silicon crystal 33. In addition, a recess 33 a for inserting the bonding material 34 is provided at the right end of the rod-like silicon crystal 33.

  After the bonding material 34 is put in the recess 33a at the right end of the rod-like silicon crystal 33, the right end is fitted into the plate-like silicon crystal 32, the left side is fitted into the plate-like silicon crystal 31, and the left end is penetrated. Next, the bonding material 34 is put into the small hole 31 a of the plate crystal 31. While maintaining this state, it is put into an electric furnace, and is brought to a temperature and atmosphere suitable for the bonding material 34. When a predetermined condition is reached, the bonding material melts and enters the gap between the bonding surfaces. By cooling from this state, the rod-like silicon crystal 33 and the plate-like silicon crystals 31 and 32 are firmly joined. Here, the cross-sectional shape of the rod-shaped crystal 33 is not limited to a circular shape, and a similar shape can be obtained by a quadrangular shape, a triangular shape, or other shapes.

  FIG. 6 shows an example of joining two disk-like silicon crystals. In this figure, A is a plan view and a cross-sectional view of the disk-like silicon crystal 41, and a cross-sectional view of the disk-like silicon crystal 42 disposed thereon, and B and C are views showing the bonding process.

  As shown in A, the surface of one disk-like silicon crystal 41 is provided with a total of nine hemispherical depressions 41a for containing a bonding material, one at the center and eight at the periphery. Then, after putting the bonding material in the recess 41 a, the flat disk-shaped silicon crystal 42 is superimposed on the upper surface of the disk-shaped silicon crystal 41. As a result, the state shown in B is obtained. Next, while maintaining the overlapped state, it is turned upside down by means (not shown) to obtain the state shown in C. By this inversion, the bonding material 43 is present above the contact surface between the plate-like silicon crystals 41 and 42 which are the bonding surfaces. Here, a weight (not shown) is placed in the center of the disk-like silicon crystal 41. While maintaining this state, it is put in an electric furnace, and is brought to a temperature and atmosphere suitable for the bonding material 43. When a predetermined condition is reached, the bonding material 43 melts and enters the gap between the bonding surfaces. By cooling from this state, the two plate-like silicon crystals 41 and 42 are firmly joined. Here, not only the disk-shaped crystals 41 and 42 but also a planar shape of a quadrangle, a triangle, or other shapes can be similarly joined. The shape of the recess 41a is not limited to a hemispherical shape, and may be other shapes.

  FIG. 7 is a view for explaining a method of manufacturing a silicon heater by bonding a rod-shaped silicon electrode to a square plate-like silicon crystal in which a slit for defining a current path is formed. In this figure, A is a plan view of a square plate-like silicon crystal, and B is a front view showing a bonding process.

  As shown in A, a slit 51 b for defining a current path is formed on the upper surface of the square plate-like silicon crystal 51. Further, holes 51 a for inserting a bonding material are formed at both ends of the current path of the square plate-like silicon crystal 51, that is, at two corners on the diagonal line of the upper surface of the square plate-like silicon crystal 51.

  Then, as shown in B, the upper surface of the silicon electrode 52 is brought into contact with the lower surface of the square plate-like silicon crystal 51 so that the silicon electrode 52 is positioned directly below the hole 51a. Next, the bonding material 53 is put into the hole 51a, put in an electric furnace while maintaining the state, and the temperature and atmosphere suitable for the bonding material as described above are reached, and when the predetermined condition is reached, the bonding material 53 is melted and bonded. It enters a gap between the surfaces (the upper surface of the silicon electrode 52 and the lower surface of the square plate-like silicon crystal 51). By cooling from this state, the rectangular silicon crystal 51 and the electrode 52 are firmly bonded. Here, not only the square plate-like crystal 51 but also a planar shape of a circle, a triangle, or other shapes can be similarly joined.

  Next, examples of the present invention will be described. The present invention is not limited by these examples.

[Example 1]
Commercially available 99.999% (5N) germanium powder was used as the bonding material. About 100 mg of this germanium powder is uniformly placed in the center of a rectangular plate-shaped silicon single crystal having a size of 40 mm long × 50 mm wide × 24 mm thick, and a cylindrical silicon single crystal having a diameter of 20 mm and a height of 30 mm is placed thereon. It was. This was put into an electric furnace and evacuated with a vacuum pump. The inside of the furnace was made 1 atmosphere with argon gas added with about 20% hydrogen gas, and the temperature was raised to 1000 ° C. at a rate of 700 ° C. per hour. This gas was continuously flowed at 500 cc / min up to 1000 ° C.

When the temperature reaches 1000 ° C., germanium sandwiched between the rectangular plate-like silicon single crystal and the columnar silicon single crystal is higher than its melting point of 936 ° C. by about 60 ° C. or more. Here, a light force was applied from the top of the cylindrical silicon single crystal, and then returned to room temperature at a rate of about 1000 ° C. per hour. When the adhesion strength between the extracted rectangular plate-like silicon single crystal and the cylindrical silicon single crystal was measured, it was 10 kg / cm ² or more, and it was confirmed that they were firmly bonded.

[Example 2]
Commercial 99.99% (4N) germanium dioxide powder was used as the bonding material. Approximately 50 mg of this germanium dioxide powder is uniformly placed in the center of a rectangular plate-shaped silicon single crystal having a size of 40 mm long × 50 mm wide × 24 mm thick, and a cylindrical silicon single crystal having a diameter of 20 mm and a height of 30 mm is placed thereon. I put it. This was put into an electric furnace and evacuated with a vacuum pump. The inside of the furnace was made 1 atmosphere with pure water argon gas added with about 20% oxygen gas, and the temperature was increased to 1200 ° C. at a rate of 700 ° C. per hour. This gas was continuously flowed at 500 cc per minute up to 1200 ° C.

When the temperature reaches 1200 ° C., germanium dioxide sandwiched between the rectangular plate-like silicon single crystal and the cylindrical silicon single crystal is higher than its melting point 1116 ° C. by about 80 ° C. or more. Here, a light force was applied from the top of the cylindrical silicon single crystal, and then the temperature was returned to room temperature at a rate of about 1000 ° C. per hour. When the adhesive strength between the extracted rectangular plate-like silicon single crystal and the cylindrical silicon single crystal was measured, it was 10 kg / cm ² or more, as in Example 1, and it was confirmed that they were firmly joined.

It is a germanium-silicon phase diagram. It is a figure for demonstrating the method to join rod-shaped silicon crystals. It is a figure for demonstrating an example of the method of joining a plate-shaped silicon crystal to the upper and lower ends of a rod-shaped silicon crystal. It is a figure for demonstrating another example of the method of joining a plate-shaped silicon crystal to the upper and lower ends of a rod-shaped silicon crystal. It is a figure for demonstrating the method to join a plate-shaped silicon crystal in the state which put the rod-shaped silicon crystal on the side. It is a figure which shows the example which joins two disk-shaped silicon crystals. It is a figure for demonstrating the method to join a silicon electrode to the square-plate-like silicon crystal in which the slit for defining an electric current path was formed, and to manufacture a silicon heater.

Explanation of symbols

  1, 2, 13, 23, 33 ... Rod-like silicon crystal, 3 ... Bonding material, 4 ... Gap between joint surfaces, 11, 12, 21, 22, 31, 32 ... Plate-like silicon crystal , 41, 42... Disc-shaped silicon crystal, 51... Square-plate silicon crystal, 52.

Claims (9)

  A step of disposing a bonding material that fuses with silicon at a temperature lower than the melting point of silicon between a plurality of silicon crystals to be bonded; and the bonding material and the silicon crystal are equal to or higher than the melting point of the bonding material and lower than the melting point of silicon. A method for bonding silicon crystals, comprising: a step of heating to a temperature; and a step of cooling and solidifying the heated bonding material and silicon crystal.   2. The method for bonding silicon crystals according to claim 1, wherein the bonding material is germanium.   2. The method for bonding silicon crystals according to claim 1, wherein the bonding material is a silicon-germanium alloy.   2. The method for bonding silicon crystals according to claim 1, wherein the bonding material is germanium dioxide.   The method for bonding silicon crystals according to any one of claims 1 to 4, wherein the bonding material has a shape of powder, paste, thin plate, granular, rod, or ring. How to join.   6. The method for bonding silicon crystals according to claim 1, wherein one of the plurality of crystals has a recess for containing the bonding material.   4. The method for bonding silicon crystals according to claim 2, wherein the bonding material and the silicon crystal are heated in an atmosphere of an inert gas, a hydrogen gas, or a mixed gas thereof.   5. The method for bonding silicon crystals according to claim 4, wherein the bonding material and the silicon crystals are heated in an atmosphere of oxygen gas, water vapor, or a mixed gas thereof.   A silicon crystal product having a plurality of silicon crystals bonded by the method according to claim 1.

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