JP2001129764A - Tool for machining silicon and its manufacturing method, and machining method using the tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tool for machining silicon using silica abrasive grains, causing mechanochemical action on silicon without forming a reaction product that is a contamination on silicon, and to provide its manufacturing method and a machining method using the tool. SOLUTION: A binder resin (a mixture) including the silica abrasive grains is obtained by adding silica, together with an additive such as a solid lubricant if necessary, into a liquid resin, and stirring and mixing it. An abrasive grain rate of silica is set to 10-70 vol.%, while an average grain diameter of the silica grains is set to 0.8 nm to 10 μm. Then a grinding wheel 1 composed of the silica abrasive grains is obtained by a grinding wheel formation method suitable for each the binder and is mounted on a grinding part 10 of a machining machine to grind a silicon wafer 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixed abrasive processing tool for grinding silicon with high quality and high efficiency, a method of manufacturing the same, and a processing method using the tool.

[0002]

2. Description of the Related Art Conventionally, in the finishing of a silicon wafer, polishing using a colloidal silica as an abrasive slurry and a flexible polishing cloth as a tool has been performed. However, in the polishing process, since a slurry is used, problems such as poor processing environment, waste liquid treatment, high running cost, low processing efficiency, and low shape accuracy (flatness) occur. For this reason, it is desired that the finish processing of the silicon wafer is performed by a fixed abrasive processing method, that is, a fixed abrasive processing tool such as a grinding wheel or a polishing film, and some tools have been devised and developed.

Here, as a prior art focusing on the fact that barium carbonate causes a mechanochemical reaction with silicon, for example, JP-A-5-285844 (hereinafter referred to as a first conventional example) and JP-A-5-285847 Gazette (hereinafter, referred to as a second conventional example) or JP-A-10-329.
No. 032 (hereinafter referred to as a third conventional example).

In the first to third conventional examples,
Constructs a grinding wheel using barium carbonate for the abrasive grains, utilizing the fact that a mechanochemical reaction occurs between the abrasive grains and the silicon, free grinding abrasive polishing finish equivalent, no processing damage remains, extremely high The aim is to get the quality of the machined surface. By using barium carbonate for the abrasive grains, it is possible to replace conventional polishing with grinding.

On the other hand, silica has a mechanochemical action on silicon, and since the constituent elements are silicon and oxygen, there is no formation of a reaction product as a contamination on silicon. Furthermore, since silica is higher in mechanical hardness than barium carbonate, high removal efficiency can be realized while maintaining high processed surface quality.

[0006] For producing resin-bonded grindstones using silica as an aggregate, for example, Japanese Patent Application Laid-Open No. 8-27636 is disclosed.
No. 6 (hereinafter referred to as a fourth conventional example). Examples of a grinding wheel using silica as abrasive grains for a sapphire substrate include, for example, JP-A-5-2858.
No. 43 (hereinafter referred to as a fifth conventional example),
Japanese Patent Application Laid-Open No. 166259 (hereinafter, referred to as a sixth conventional example) and Japanese Patent Application Laid-Open No. 9-47969 (hereinafter, referred to as a seventh conventional example) are available.

In the fourth conventional example, silica is not used as abrasive grains exhibiting a mechanochemical action.
The use as an aggregate improves the dispersibility of abrasive grains, adjusts the specific gravity of a binder, and the like.

In the fifth and sixth conventional examples,
A sapphire polishing grindstone is constructed using silica, which is mechanically softer than sapphire, as abrasive grains, and high-quality grinding of sapphire is attempted by utilizing the fact that a mechanochemical reaction occurs at the contact point between the abrasive grains and sapphire.

In the seventh conventional example, ultrafine powder (several tens of nm or less) of silica is used as abrasive grains, and a silicon wafer or the like is not clogged by a grinding wheel formed with a predetermined porosity without clogging. The mirror polishing is intended to be performed with high precision. It should be noted that the one described in the seventh conventional example does not have a main purpose of causing mechanochemical action by using silica abrasive grains.

[0010]

However, the first to the first problems
When barium carbonate is used as abrasive grains as in the third conventional example, in a mechanochemical reaction between barium carbonate and silicon, those compounds (compounds composed of barium, silicon and oxygen) are formed on silicon. It will be a contamination as it is,
There is a possibility that the quality of the processed surface may be deteriorated, and a cleaning process is required as a post process. Further, barium carbonate has a lower mechanical hardness than silicon and can easily realize high-quality processing. However, on the other hand, there is a problem that the removal efficiency is too low for use in a production process.

On the other hand, silica is generally used as an aggregate for the purpose of improving the dispersibility of abrasive grains and adjusting the specific gravity of a binder in the production of a resin-bonded grindstone as in the fourth conventional example. In the fifth and sixth conventional examples, they are used as abrasive grains for sapphire polishing, but no consideration is given to using silica as abrasive grains for silicon wafers. In the seventh conventional example, since ultrafine silica (several tens of nm or less) of silica is used as abrasive grains, it is difficult to achieve the above-described high removal efficiency.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and to produce a mechanochemical action on silicon and not to form a reaction product serving as contamination on silicon by using silicon abrasive grains. An object of the present invention is to provide a tool for use, a method for manufacturing the same, and a processing method using the tool.

[0013]

According to the first aspect of the present invention,
A silicon processing tool for processing a silicon wafer with fixed abrasive grains, wherein the abrasive grains are formed of silica.

[0014] Silica causes a mechanochemical action on silicon, and since its constituent elements are silicon and oxygen, there is no formation of a reaction product as a contamination on the silicon wafer. Furthermore, it is excellent in mechanical hardness and can realize high removal efficiency while maintaining high processed surface quality.

According to a second aspect of the present invention, in the first aspect, the primary particles of the silica have an average particle diameter of 0.8 nm to 10 μm.
m.

If the average particle size of the silica used as the abrasive grains is less than 0.8 nm, the mechanical action becomes too small and the desired mechanochemical action cannot be generated. On the other hand, if it exceeds 10 μm, the mechanical action is too strong,
There is a possibility that processing damage may occur on the surface of the silicon as the workpiece.

The invention according to claim 3 is characterized in that in claim 1 or 2, the silica has an abrasive grain ratio of 10 to 70% by volume.

When the abrasive grain ratio is less than 10% by volume, no action is exerted on the silicon by the silica abrasive grains. On the other hand, when it exceeds 70% by volume, the grinding stones are clogged, resulting in unstable processing. Easy to fall, and the amount of binder becomes insufficient,
There is a possibility that the tool strength applicable to machining cannot be maintained.

According to a fourth aspect of the present invention, in the first to third aspects, the binder forming the silicon processing tool together with the abrasive grains is made of a material that does not cause an endothermic reaction during processing.

As described above, silica has a mechanochemical action on silicon as described above. At this time, it is necessary that the processing atmosphere temperature be high enough to cause the chemical action. Therefore, as a binder material for tools,
For example, when a material having a low melting point such as an acrylic resin is used, the binder is melted by processing heat during processing, and at that time, an endothermic reaction occurs, thereby lowering the processing atmosphere temperature. As a result, it becomes impossible to generate a mechanochemical action. Therefore, for example, in the case of a polymer material, by using a material such as a phenol resin or a polyimide resin or a ceramic as the binder, it is possible to prevent the binder from melting and causing an endothermic reaction at the time of processing. An action can be generated.

According to a fifth aspect of the present invention, in the first to fourth aspects, the additive to be contained in the silicon processing tool is made of a material that does not cause an endothermic reaction during processing.

Various additives are contained in the abrasive processing tool for the purpose of improving the strength and lubricity of the tool.
Here, as described above, when a material that causes an endothermic reaction during processing is used as an additive, the temperature of the processing atmosphere is lowered, and as a result, it becomes impossible to generate a mechanochemical effect. Therefore, by using a material such as carbon or molybdenum disulfide as the additive, it is possible to prevent the additive from melting and causing an endothermic reaction at the time of processing, and to generate a mechanochemical effect.

According to a sixth aspect of the present invention, there is provided the method for manufacturing a silicon processing tool according to any one of the first to fifth aspects, wherein a mixing step of stirring and mixing the binder material and the silica abrasive grains is performed. And a forming step of forming the mixture generated in the mixing step into a tool.

As the binder material, depending on the processing purpose,
Resins, ceramics, metal materials, silicates, magnesia, and the like can be used, but it is possible that no binder is included. In the absence of any binder, the silica abrasive grains are linked together by siloxane bonds to form a tool. For example, in the case of manufacturing a resin-bonded grindstone, a method of firing and drying the mixture under pressure is used. In addition, a manufacturing method utilizing the electrophoresis phenomenon (see Japanese Patent Application No. 10-349063) can be used. In the case of manufacturing a vitrified whetstone, a method of baking under pressure and drying the mixture is used.
When manufacturing a metal bond grindstone, an electrodeposition method, a hot pressing method, or the like is used. When a film-shaped tool is manufactured, the mixture is applied onto a resin film (for example, a polyethylene terephthalate film) as a base material.
In addition, although silica is used as abrasive grains, if necessary,
Additives such as solid lubricants can also be included in the binder.

According to a seventh aspect of the present invention, there is provided a process for machining a silicon wafer using the silicon processing tool according to any one of the first to fifth aspects.

As the processing machine used in this step, any type of machining system can be adopted according to the form of the tool and the like.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment of the present invention will be described. However, the present invention is not limited to this, and silica using a mechanochemical action on silicon is used as abrasive grains. The present invention also includes a wide range of applications of fixed abrasive processing tools such as grinding wheels and polishing films, manufacturing methods thereof, and processing methods using the tools.

The silicon processing tool of the present embodiment for processing a silicon wafer with fixed abrasive grains is manufactured by a mixing step and a forming step. In the mixing step, silica is put into a liquid resin together with an additive such as a solid lubricant as needed, and stirred and mixed to obtain a binder resin (mixture) containing silica abrasive grains.

At this time, the abrasive ratio of silica is set to 10 to 70% by volume, and the average particle size of the silica particles is 0.8 nm.
Set to に 10 μm.

Also, the binder material is not limited to resin,
Ceramics, metals, and the like may be used according to the processing purpose, but a material that does not cause an endothermic reaction during processing is used for the above-described reason. For example, a phenol resin, a polyimide resin, or the like is used as the polymer material.

As the additive, a material which does not cause an endothermic reaction at the time of processing for the above-mentioned reason is used. For example, carbon, molybdenum disulfide, or the like is used.

After completion of the mixing step, a grindstone of silica abrasive grains is obtained by a grindstone forming method suitable for each binder.

Here, when manufacturing a resin bond grindstone or a vitrified grindstone, the mixture obtained in the mixing step is fired under pressure and dried. When manufacturing a metal bond grindstone, an electrodeposition method, a hot pressing method, or the like is used. In the case of manufacturing a film-shaped tool, an application step of applying a binder resin (mixture) on a resin film is required prior to the molding step. In this application step, the mixture is applied on a resin film (for example, a polyethylene terephthalate film) as a base material.

The substrate of the film-shaped tool is not limited to the above-mentioned polyethylene terephthalate film, but may be a plastic film such as polyimide, polycarbonate, or the like, synthetic paper, nonwoven fabric, metal foil, or the like.

As a means for applying the mixture to the substrate, a wire bar coder, gravure coder, reverse roller coater, knife coater, or the like may be used.

The method for processing a silicon wafer according to the present embodiment includes a step of processing the silicon wafer with fixed abrasive grains using the silicon processing tool manufactured as described above. Examples of the processing method include wafer surface grinding, wafer surface polishing film processing, wafer outer peripheral portion grinding, wafer outer peripheral polishing film processing, and the like.

In this step, a grindstone of silica abrasive grains or a polishing film of silica abrasive grains is mounted on a processing machine, and is ground to a predetermined size.

At this time, the machining machine is not particularly limited, and a machining system according to a tool form or the like may be appropriately employed.

In this embodiment, by using silica as abrasive grains, silicon can be finished to a very high processed surface quality without processing damage without causing contamination. As a result, compared to the polishing process currently used for finishing silicon wafers, the same surface quality can be achieved with higher efficiency, and at the same time, higher shape accuracy (flatness) can be achieved. Obtainable. Furthermore, unlike the polishing process, since free abrasive slurry is not used, the environment is excellent and the cost can be reduced.

[0040]

An embodiment of the present invention will be described below. [Example 1] First, fumed silica having an average particle size of 30 nm (abrasive grain ratio 50% by volume) is put into a liquid acrylic resin together with a wetting agent, and mixed with a homogenizer for 5 minutes with stirring.
Then, the obtained binder resin is baked under pressure at a pressure of 50 MPa and a heating temperature of 150 ° C. for 30 minutes.
After drying for a minute to remove volatile components, a resin bonded grindstone of silica abrasive grains is obtained. At this time, the type of the binder is not limited to the resin, and any material that does not cause an endothermic reaction during processing may be any of a resin, a ceramic, and a metal, and a grinding stone forming method suitable for each binder. Is adopted. Also, as the additive (wetting agent), a material that does not cause an endothermic reaction during processing is employed.

The grinding wheel manufactured as described above was mounted on a vertical infeed grinder, and an 8-inch silicon wafer (finished lapping) was ground. As a result, the processing was performed for 30 seconds (30 μm allowance) and processed to 1 nmRy or less. Surface roughness,
A micro-crack free (by cross-sectional TEM observation) high quality processed surface could be obtained.

FIG. 1 shows the above-described grinding wheel 1 mounted on a rotary grinding section 10 of a vertical infeed grinding machine in a ring shape, and a silicon wafer 2 mounted and fixed on a work mounting table 20. Show. The rotary grinding unit 10 rotates at a predetermined speed, and the work table 20 rotates in the same direction at a lower speed than the predetermined speed. In addition, the workpiece mounting table 20 is rotated by a rotation axis different from that of the rotary grinding unit 10 to feed the silicon wafer 2 to the grinding position at a constant speed, and continuously grind to a desired size.

Example 2 First, colloidal silica having an average particle size of 80 nm (abrasive grain ratio 65% by volume) was put into a liquid urethane resin, and mixed by stirring with a homogenizer for 5 minutes. Then, the obtained binder resin is applied on a polyethylene terephthalate film so as to have a thickness of 3 μm. next,
Drying and curing are performed by heating for 10 minutes to obtain a polished film.

With the polishing film thus manufactured, 6
As a result of processing the outer periphery of an inch silicon wafer, 2
In a minute of processing, a scratch-free high quality processed surface could be obtained.

Here, FIG. 2 shows that the above-mentioned polishing film 33 is wound around a supply spool 31 and a take-up spool 32,
An outer peripheral portion or a notch portion of the silicon wafer 2 is pressed against the polished surface of the polishing film 33 to apply a load.
3 shows a processing machine for polishing by unwinding and winding 3.

Example 3 First, colloidal silica having an average particle size of 30 nm (abrasive grain ratio: 20% by volume) and a water-soluble polymer (binder, 30% by volume) were mixed with a solvent (water, 50% by volume).
And mix. Then, an anode and a cathode were provided in the obtained mixed solution, a voltage of DC 10 V was applied between the electrodes, and electrophoresis was performed for 60 minutes while stirring and mixing the mixed solution at a low speed. Since an abrasive layer having a thickness of about 5 nm was formed around the anode electrode, the abrasive layer was cut off from the anode electrode and shaped into a 5-nm-thick abrasive pellet. Thereafter, drying was performed at 100 ° C. for 1 hour to obtain a resin bond whetstone of silica abrasive grains.

The grinding wheel thus manufactured was mounted on a vertical infeed grinder (shown in FIG. 1), and an 8-inch silicon wafer (finished lapping) was ground.
A processing surface roughness of 1 nmRy or less and a high-quality micro-crack-free (by cross-sectional TEM observation) high-quality processed surface could be obtained by processing for 30 seconds (removal amount of 30 μm).

[0048]

According to the first, sixth and seventh aspects of the present invention,
Since silica is used as the abrasive grains for processing the fixed abrasive grains of the silicon wafer, high removal efficiency can be realized while maintaining high quality of the machined surface by utilizing the mechanochemical action of the silica.

That is, silica causes a mechanochemical action on silicon, and since the constituent elements are silicon and oxygen, there is no formation of a reaction product serving as a contamination on silicon. Furthermore, since silica is higher in mechanical hardness than barium carbonate, high removal efficiency can be realized while maintaining high processed surface quality.

Thus, compared with the polishing processing currently used for the finishing processing of silicon wafers, the same surface quality can be achieved with higher efficiency, and at the same time,
Higher shape accuracy (flatness) can be obtained.

Furthermore, unlike the polishing process, since no free abrasive slurry is used, the environment is excellent and the cost can be reduced.

According to the second, sixth and seventh aspects of the present invention, the primary particles of the silica have an average particle size of 0.8 nm to 10 μm.
Therefore, the mechanochemical action of silica on silicon can be sufficiently generated. If the average particle size of the silica is less than 0.8 nm, the mechanical action is too small to produce the desired mechanochemical action, while if it exceeds 10 μm, the mechanical action is too strong and the mechanical action is too strong. This is not preferable because processing damage may occur on the surface of the silicon material.

According to the third, sixth and seventh aspects of the present invention, the silica has an abrasive grain ratio of 10 to 70% by volume, so that the mechanochemical action of silica on silicon is generated and the necessary tool strength is maintained. It is possible to In addition, when the abrasive grain ratio is less than 10% by volume, the action of silica abrasive grains on silicon does not occur. On the other hand, when the abrasive grain ratio exceeds 70% by volume, grinding stones are clogged, and as a result, machining becomes unstable. This is not preferable because it is liable to occur, the amount of the binder becomes insufficient, and the strength of the tool applicable to machining cannot be maintained.

According to the fourth, fifth, sixth and seventh aspects of the present invention, since a material which does not cause an endothermic reaction during processing is used as a binder and / or an additive in a silicon processing tool, a mechanochemical effect is not generated. It is possible to suppress a decrease in the processing atmosphere temperature, which is a hindrance factor, and as a result, it is possible to achieve extremely high processing surface quality with high processing efficiency.

As described above, according to the present invention, by producing a mechanochemical action on silicon, it is possible to finish the processing surface with extremely high quality such as processing damage-free, and to obtain a reaction product which causes contamination. Tool that uses silica abrasive grains, does not form on silicon, a method for manufacturing the same, and a processing method using the tool.

[Brief description of the drawings]

FIG. 1 is a view showing a method for machining a silicon wafer according to a first embodiment of the present invention.

FIG. 2 is a view showing a method for machining a silicon wafer in a second embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Grinding grindstone 2 Silicon wafer 10 Rotary grinding part 20 Workpiece mounting table 31 Supply spool 32 Take-up spool 33 Polishing film

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B24D 3/34 B24D 3/34 Z H01L 21/304 622 H01L 21/304 622F F-term (Reference) 3C063 AA02 AB02 BB01 BB07 BB18 BC01 BC03 BC08 BC10 BD01 BD04 EE10 FF23

Claims (7)

[Claims] 1. A silicon processing tool for processing fixed abrasive grains on a silicon wafer, wherein the abrasive grains are formed of silica. 2. An average particle diameter of primary particles of said silica is 0.8.
2. The silicon processing tool according to claim 1, wherein the thickness is from 10 nm to 10 μm. 3. The silicon processing tool according to claim 1, wherein the silica has an abrasive grain ratio of 10 to 70% by volume. 4. The silicon processing tool according to claim 1, wherein the binder that forms the silicon processing tool together with the abrasive grains is made of a material that does not cause an endothermic reaction during processing. . 5. The silicon processing tool according to claim 1, wherein the additive contained in the silicon processing tool is made of a material that does not cause an endothermic reaction during processing. 6. The method for producing a silicon processing tool according to claim 1, wherein the mixing step includes stirring and mixing the binder material and the silica abrasive grains. A method for producing a silicon processing tool, comprising: a molding step of molding a mixture into a tool. 7. A processing method comprising the step of machining a silicon wafer using the silicon processing tool according to claim 1.