JP2002292556A - Slurry, grindstone, pad and abrasive fluid for mirror polishing of silicon wafer, and mirror polishing method using these materials - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide slurry, a grindstone, a pad and abrasive fluid for mirror polishing of a silicon wafer, and a polishing method for the silicon wafer using these materials, by which a mirror polishing speed is remarkably improved, a mirror finished surface is obtained for a short time and a throughput is further improved. SOLUTION: The slurry, the grindstone, the pad and the abrasive fluid for mirror polishing of the silicon wafer are constituted so that fine grains of an alkali earth metal carbonate as abrasive grains may contain a water-soluble carbonate as an abrasive accelerator. In the polishing method of the silicon wafer, the fine grains of the alkali earth metal carbonate is used as the abrasive grains, and wet polishing is carried out in the presence of water and the water- soluble carbonate.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a silicon wafer mirror polishing slurry, a grindstone, a pad and a polishing liquid capable of mirror polishing a silicon wafer at a high speed, and a method of mirror polishing a silicon wafer using the same. About.

[0002]

2. Description of the Related Art Conventionally, as a method for mirror polishing a silicon wafer, for example, a multi-stage polishing method using a nonwoven fabric type or suede type soft pad using a slurry containing silica particles and an alkali such as KOH or colloidal silica as an abrasive. Polishing methods are known. However, in the conventional mirror polishing method, the polishing rate is extremely low, it takes a long time to obtain a mirror surface, and the productivity is extremely low. In other words, as a pre-process of mirror finishing, after the lapping process, the processing damage layer is removed by an etching process, and then, in order to obtain a target quality wafer,
At least three or more stages of multi-stage polishing under different polishing conditions must be performed, and the number of steps is large, and this is a mirror polishing process with low throughput. In addition, silica is harder than silicon, and thus easily damages wafers, such as scratches and damaged layers. In addition, since the polishing method uses a soft pad, sagging of an edge is likely to occur and processing accuracy is not sufficient. was there.

On the other hand, as a mirror polishing method for a silicon wafer capable of solving the above-mentioned problems, a silicon wafer is subjected to a surface processing until the surface roughness Ra becomes 150 nm or less, and an abrasive containing barium carbonate particles is further applied to the processed surface. 2. Description of the Related Art A mirror polishing method of a silicon wafer to be polished by using is known.
In this mirror polishing method for a silicon wafer, the mirror polishing speed is improved, the mirror surface is obtained in a short number of steps and the mirror surface is obtained in a short time, the throughput is improved, and the wafer is damaged such as scratches and damaged layers. Has the advantage of not having. However, recently, there has been a demand for a method for mirror-polishing a silicon wafer, which has a significantly improved mirror-polishing speed, can obtain a mirror surface in a short time, and further improves throughput.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems of the prior art, and an object set specifically for solving the problems is that the mirror polishing speed is remarkably improved. A mirror polishing slurry for a silicon wafer, in which a mirror surface is obtained in a short time and the throughput is further improved,
An object of the present invention is to provide a grindstone, a pad, a polishing liquid, and a method for polishing a silicon wafer using the same.

[0005]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems of the prior art.
The inventors have found that when a silicon wafer is wet-polished in the presence of a water-soluble carbonate, the polishing rate is drastically increased, and have completed the present invention. That is, the silicon wafer mirror polishing slurry according to claim 1 of the present invention (hereinafter referred to as "polishing slurry") comprises water, alkaline earth metal carbonate fine particles as abrasive grains, and water-soluble as polishing accelerator. And at least a basic carbonate.

When a silicon wafer is polished using the polishing slurry, a side reaction which hinders a mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer can be suppressed efficiently. As a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, since the mirror polishing slurry contains alkaline earth metal carbonate fine particles as abrasive grains, a mirror surface can be easily obtained without generating scratches.

The method for mirror-polishing a silicon wafer according to claim 2 (hereinafter referred to as “first polishing method”)
The mirror polishing slurry for silicon wafer according to claim 1,
The method is characterized in that the silicon wafer is polished while being supplied between a silicon wafer and a polishing plate for polishing a silicon wafer made of a plastic plate. When the first polishing method is used, it is possible to obtain not only an excellent polishing rate but also a wafer shape after polishing, in particular, a highly accurate shape without edge sagging at the outer peripheral portion of the wafer. Since a commercially available plastic plate can be used, the mirror polishing cost is low.

[0008] The silicon wafer mirror polishing wheel (hereinafter referred to as "polishing wheel") according to the third aspect of the present invention comprises alkaline earth metal carbonate fine particles as abrasive grains and water-soluble carbonate as a polishing accelerator. And at least the following. The mirror polishing method for a silicon wafer according to claim 4 (hereinafter referred to as “second polishing method”)
The present invention is characterized in that the silicon wafer is polished while supplying water between the silicon wafer and the grinding wheel for mirror polishing the silicon wafer according to the third aspect.

When the silicon wafer is polished under a wet condition while supplying water using the mirror polishing whetstone, the water-soluble carbonate in the whetstone is eluted, and the alkaline earth metal carbonate as the abrasive and the silicon wafer are removed. Can effectively suppress the side reaction which hinders the mechanochemical reaction (main reaction), and as a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, since alkaline earth metal carbonate fine particles are contained as abrasive grains, a mirror surface can be easily obtained without generating scratches.

A silicon wafer mirror polishing pad (hereinafter referred to as a "polishing pad") according to a fifth aspect of the present invention comprises alkaline earth metal carbonate fine particles as abrasive grains and water-soluble carbonate as a polishing accelerator. And at least the following. The mirror polishing method for a silicon wafer according to claim 6 (hereinafter referred to as “third polishing method”)
The present invention is characterized in that the silicon wafer is polished while supplying water between the silicon wafer and the silicon wafer mirror polishing pad of the fifth aspect.

When the silicon wafer is polished under a wet condition while supplying water using the mirror polishing pad, water-soluble carbonate in the pad is eluted, and the alkaline earth metal carbonate as abrasive grains and the silicon wafer are removed. Can effectively suppress the side reaction which hinders the mechanochemical reaction (main reaction), and as a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, since alkaline earth metal carbonate fine particles are contained as abrasive grains, a mirror surface can be easily obtained without generating scratches.

The polishing liquid for mirror-polishing a silicon wafer according to claim 7 (hereinafter referred to as "polishing liquid") comprises an aqueous solution of a water-soluble carbonate. And
A mirror polishing method for a silicon wafer according to claim 8 (hereinafter, referred to as a mirror polishing method).
The "fourth polishing method") supplies the polishing liquid for mirror polishing a silicon wafer according to claim 7, between the silicon wafer and a grindstone or a pad containing fine particles of alkaline earth metal carbonate as abrasive grains. The method is characterized by polishing the silicon wafer while polishing.

When a silicon wafer is polished with the polishing liquid for mirror polishing, the presence of the water-soluble carbonate prevents the mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer. Can be efficiently suppressed, and as a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, since the grindstone or the pad contains alkaline earth metal carbonate fine particles as abrasive grains, polishing by a mechanochemical reaction is promoted, and no scratch is generated, and a mirror surface can be easily obtained. .

The method for mirror-polishing a silicon wafer according to the ninth aspect is characterized in that the silicon wafer is wet-polished in the presence of water and a water-soluble carbonate by using alkaline earth metal carbonate fine particles as abrasive grains. And When a silicon wafer is polished using the mirror polishing method for a silicon wafer, the presence of the water-soluble carbonate hinders a mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer. The side reaction is suppressed efficiently, and the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, the shape of the polished wafer, especially the edge portion of the outer peripheral portion of the wafer, has high precision with no sagging. Can be obtained.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described.
The present invention will be described in more detail. This embodiment is for specifically describing the present invention, and does not limit the contents of the invention unless otherwise specified.

"Slurry for polishing" This polishing slurry contains at least water, fine particles of alkaline earth metal carbonate as abrasive grains, and water-soluble carbonate as a polishing accelerator. The carbonate is dissolved in the water. Examples of the alkaline earth metal carbonate fine particles as the abrasive grains include barium carbonate (BaCO ₃ ) fine particles, calcium carbonate (CaCO ₃ ) fine particles, magnesium carbonate (MgCO ₃ ) fine particles, and strontium carbonate (SrCO ₃ ).
₃ ) Fine particles can be mentioned, and the particle size is from 0.01 μm to 10 μm from the viewpoint of polishing characteristics and slurry dispersibility.
Are preferred. The concentration of the alkaline earth metal carbonate fine particles as abrasive grains is not particularly limited as long as it is well dispersed, but is usually 0.5 to 30% by weight.
Is preferred. If the abrasive grain concentration is less than 0.5% by weight, the polishing rate is reduced and the practicality is lacking. On the other hand, if the abrasive grain concentration exceeds 30% by weight, the particles that do not contribute to the polishing process increase, and the material cost increases. This increases the polishing cost, which is not preferable.

The water-soluble carbonate is not particularly limited as long as it is excellent in solubility in water and does not contain heavy metals. For example, potassium carbonate (K ₂ CO 3)
₃ ), potassium hydrogen carbonate (KHCO ₃ ), sodium carbonate (NaCO ₃ ), sodium hydrogen carbonate (NaHC)
O ₃ ), ammonium carbonate ((NH ₄ ) ₂ CO ₃ ), ammonium hydrogen carbonate (NH ₄ HCO ₃ ), and the like. The amount of the water-soluble carbonate is not particularly limited as long as it is within the range of dissolving in water, for example, 0.1 to 0.1 with respect to alkaline earth metal carbonate fine particles as abrasive grains. A range of 10% by weight is preferred. If the amount of the water-soluble carbonate is less than 0.1% by weight, the effect of increasing the polishing rate is not exhibited. On the other hand, if it exceeds 10% by weight, the dispersion stability of the slurry is undesirably reduced.

If necessary, alcohols such as methanol, ethanol and propanol, and surfactants such as polycarboxylates may be added to the polishing slurry to improve dispersibility. it can. Then, the polishing slurry is obtained by adding and mixing the alkaline earth metal carbonate fine particles with the aqueous solution of the water-soluble carbonate, further adding alcohols and surfactants as necessary, It can be manufactured by dispersing by known means such as a disperser.

[First Polishing Method] In a first polishing method, the silicon wafer mirror polishing slurry is supplied between a silicon wafer and a silicon wafer polishing plate made of a plastic plate while the silicon wafer is being polished. Polish. Here, the silicon wafer before polishing is preferably a ground product having a surface roughness of 150 nm or less. The reason is,
This is because a mirror layer can be easily obtained with a thin damaged layer on the surface, and the mechanochemical reaction between the silicon wafer and the alkaline earth metal fine particles as abrasive grains easily proceeds effectively.

The material of the polishing plate for polishing a silicon wafer made of the above-mentioned plastic plate is not particularly limited, but for example, polycarbonate, vinyl chloride, epoxy,
Polyethylene terephthalate, Teflon (registered trademark),
Polyethylene, acrylic, polymethyl methacrylate, polyamide, polyacetal, polyphenylene ether,
At least one selected from the group consisting of polybutylene terephthalate, polysulfone, polyethersulfone, polyimide, polyphenylenesulfide, polybenzimidazole, polyarylate, polymethylpentene, polyamideimide and polyetheretherketone has versatility. It is preferable because it is inexpensive and has excellent mirror-polishing workability. In particular, polycarbonate or vinyl chloride is more preferable in terms of the price of the plastic plate and the improvement of the polishing rate.

The thickness of the plastic plate to be used is not limited, but a plastic plate having a thickness of about 1 mm or more is used in order to reduce the frequency of replacement due to abrasion of the plastic plate and the ease of fixing work on the surface plate. It is preferable to use a plate.

Further, grooves or fine holes are formed on the polishing surface of the polishing plate in order to spread the abrasive slurry evenly on the polishing plate or to efficiently hold the abrasive grains. Is preferred. The groove width and groove pitch are not particularly limited, and are appropriately selected depending on the size of the silicon wafer and the supply amount of the abrasive slurry.

As an example of the processing of the groove or the fine hole, for example, it is exemplified that fine irregularities are formed substantially uniformly on the entire area of the contact surface with the polishing surface of the silicon wafer, that is, on the polishing surface. it can. And since such fine irregularities are substantially uniformly formed on the polishing surface of the plastic polishing plate, the abrasive grains in the abrasive slurry are uniformly held on the polishing surface, and the polishing rate is improved, Mirror polishing with excellent uniformity with less surface roughness distribution within the silicon wafer surface is possible, and a highly accurate wafer shape after mirror polishing, especially with no edge sagging at the outer peripheral portion of the wafer, can be obtained. There is no occurrence of scratches.

The surface roughness Ra of the surface on which the fine irregularities are formed substantially uniformly is preferably 100 nm or more. Here, the surface roughness Ra refers to the average of the step between the convex portion and the concave portion measured by a contact pointer type surface roughness meter or the like. If the surface roughness is less than 100 nm, the abrasive grains contained in the abrasive slurry are not efficiently fixed to the polishing surface of the polishing plate, so that the polishing rate is reduced and the mirror polishing uniformity is not improved. The upper limit of the surface roughness Ra, that is, the maximum value of the step is not particularly limited, and is preferably equal to or less than の of the thickness in view of the strength of the plastic plate. In consideration of the surface treatment, it is preferably, for example, 500 μm or less. Since it is carried and held on the polishing surface by the relative rotational movement of the board and the silicon wafer and functions as abrasive grains, it is preferably, for example, 1000 nm or less.

The method of forming the fine irregularities is not particularly limited, but for example, diamond particles, silicon carbide particles, zirconia particles, alumina particles or the like have a count of # 800 or # 800. A method of dressing a plastic plate surface using a grindstone dresser to which small abrasive grains are fixed can be exemplified.
That is, for example, when the surface of a plastic plate is dressed for about 3 minutes, preferably for about 10 minutes using such a dresser abrasive grain, an uneven shape suitable for mirror polishing of a silicon wafer is substantially uniformly formed on the surface of the plastic plate. Can be granted. # 800 dressing abrasive
Is not preferable, it is difficult to form irregularities having a surface roughness Ra of 100 nm or more suitable for mirror polishing of a silicon wafer on a plastic plate.

The width W of the concave portion (ie, the width of the top portion) formed on the polishing surface of the polishing plate for polishing the silicon wafer is not particularly limited. The abrasive grains in the abrasive slurry preferably have an average primary particle diameter such that the primary particle diameter is smaller than the width W of the recess. If the average primary particle diameter of the abrasive grains is larger than the width W of the concave portion, the abrasive grains are not efficiently fixed on the polishing surface of the polishing plate, but simply roll, and the polishing efficiency is reduced. descend.

As a polishing apparatus or a lapping apparatus used in this polishing method, a one-sided or double-sided polishing apparatus or a lapping apparatus of a rotating platen conventionally used in silicon wafer processing can be used. The silicon wafer mirror-polishing polishing plate is stuck on a surface plate of the polishing device or the lapping device using an adhesive, or is mechanically fixed. The silicon wafer mirror-polishing polishing plate may be directly fixed to the surface plate of the polishing device or the lapping device, but may be a foamed sheet such as a conventional polishing pad or a rubber between the surface plate and the plastic plate. The elastic sheet may be interposed and fixed.

Further, in order to maintain the entire shape of the wafer, the polishing plate is fixed on a platen of a polishing device or a lapping device and then a platen correction device as conventionally performed before polishing or lapping. The shape of the polishing surface of the polishing plate is appropriately controlled by using a polishing plate or a correction ring for the polishing plate. The silicon wafer is polished under a conventional polishing or lapping condition by a polishing apparatus or a lapping apparatus to which such a polishing plate is fixed.

The polishing pressure at the time of polishing the silicon wafer in contact with the polishing plate is not particularly limited, and is usually 9.8 to 39.2 kPa (100 to 400 g).
f / cm ² ) is sufficient, but a larger polishing pressure is preferable because the pressure at the true contact point with the abrasive grains is increased and the polishing rate is improved. The number of rotations of the platen and the wafer is not particularly limited, and is usually 30 to 120 rpm.
m is sufficient, but as the number of rotations increases, the polishing rate increases. Other polishing conditions can be applied without changing the conventional polishing conditions for silicon wafers.

"Polishing Wheel" The silicon wafer mirror polishing wheel according to this embodiment contains at least alkaline earth metal carbonate fine particles as abrasive grains and a water-soluble carbonate as a polishing accelerator. I have. Then, when the silicon wafer is polished under a wet condition using this mirror polishing wheel,
Water-soluble carbonates in the grinding stone are eluted, and side reactions that hinder the mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer can be efficiently suppressed,
As a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, since alkaline earth metal carbonate fine particles are contained as abrasive grains, a mirror surface can be easily obtained without generating scratches.

The alkaline earth metal carbonate fine particles as abrasive grains used in the above-mentioned polishing grindstone are barium carbonate (BaC).
O ₃ ) fine particles, calcium carbonate (CaCO ₃ ) fine particles,
Examples thereof include magnesium carbonate (MgCO ₃ ) fine particles and strontium carbonate (SrCO ₃ ) fine particles, and the particle diameter is preferably about 0.01 μm to 10 μm from the viewpoint of polishing characteristics. In addition, the amount of the alkaline earth metal carbonate fine particles as the abrasive grains (abrasive grain ratio) is not particularly limited, but usually, it is preferably contained in a grindstone at about 50 to 95% by weight. Abrasive grain content (abrasive grain ratio) is 5
If the amount is less than 0% by weight, the polishing rate is reduced, and the practicality is poor.
On the other hand, if the blending amount of the abrasive grains (abrasive grain ratio) exceeds 95% by weight, particles that do not contribute to the polishing process increase, and the material cost increases and the polishing cost increases, which is not preferable.

The water-soluble carbonate used in the above-mentioned polishing grindstone is not particularly limited as long as it has excellent solubility in water and does not contain heavy metals. For example, potassium carbonate (K ₂ CO ₃ ) , Potassium bicarbonate (KHC
O ₃ ), sodium carbonate (NaCO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), ammonium carbonate ((N
H ₄ ) ₂ CO ₃ ), ammonium bicarbonate (NH ₄ HC)
O ₃ ) and the like. The amount of the water-soluble carbonate is not particularly limited, but is usually preferably about 0.0001 to 10% by weight in the grindstone. When the amount of the water-soluble carbonate is less than 0.0001% by weight, the effect of accelerating the polishing rate is not achieved, and the practicality is lacking. On the other hand, when the amount of the water-soluble carbonate exceeds 10% by weight, it is used for polishing. This is not preferable because the pH of water is significantly increased and the surface roughness of the wafer after mirror polishing is deteriorated.

To form the alkaline earth metal carbonate fine particles and the water-soluble carbonate into a grindstone, a mixture of these may be used to form the whole grindstone, or a portion of the grindstone that is in contact with the silicon wafer may be partially formed. In some cases, the mixture is also fixed to the grinding stone without a binder (bondless grinding stone) and solidified using a binder such as resinoid bond.
There may be a molded one (resinoid bond whetstone).
The resinoid bond used for forming the resinoid bond grindstone is not particularly limited, and a simple substance or a mixture of a thermosetting resin, a thermoplastic resin, or the like can be used. The bondless whetstone or the resinoid bond whetstone can be formed by using a generally used known forming technique.

[Second Polishing Method] In the mirror polishing method according to this embodiment, the silicon wafer is polished while supplying water between the silicon wafer and the polishing grindstone. Here, the silicon wafer before polishing is preferably a ground product having a surface roughness of 150 nm or less. The reason is,
This is because a mirror layer can be easily obtained with a thin damaged layer on the surface, and the mechanochemical reaction between the silicon wafer and the alkaline earth metal fine particles as abrasive grains easily proceeds effectively.

The polishing method according to this embodiment can be performed without any change from the conventional wet polishing method. As a specific example, the load, that is, the polishing pressure is increased while supplying water between the silicon wafer attached to the wafer support and the polishing grindstone mounted on the surface plate of the mechanical rotary polishing apparatus. A method of polishing by applying a load can be exemplified. The polishing pressure is not particularly limited, and is usually from 9.8 to 39.2 kPa (100 to
A pressure of about 400 gf / cm ² suffices, but a higher polishing pressure is preferred because the pressure at the true contact point with the abrasive grains (alkaline earth metal fine particles) increases, and the polishing rate increases. The polishing apparatus and polishing conditions may be in accordance with the first polishing method.

[Polishing Pad] The silicon wafer polishing pad according to this embodiment contains at least alkaline earth metal carbonate fine particles as abrasive grains and a water-soluble carbonate as a polishing accelerator. . When the silicon wafer is polished under wet conditions using the polishing pad, the water-soluble carbonate in the pad is eluted, and a mechanochemical reaction between the alkaline earth metal carbonate as abrasive grains and the silicon wafer (main reaction) ) Can be efficiently suppressed,
As a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. In addition, since alkaline earth metal carbonate fine particles are contained as abrasive grains, a mirror surface can be easily obtained without generating scratches.

As the abrasive used in the polishing pad,
As alkaline earth metal carbonate fine particles, barium carbonate
(BaCO₃) Fine particles, calcium carbonate (CaC)
O₃) Fine particles, magnesium carbonate (MgCO₃) Fine particles
Strontium carbonate (SrCO ₃) List the fine particles
And the particle size is 0.0% from the viewpoint of polishing characteristics.
Those having a thickness of about 1 μm to 10 μm are preferred.

The water-soluble carbonate used for the polishing pad is not particularly limited as long as it is excellent in solubility in water and does not contain heavy metals.
Potassium carbonate (K ₂ CO ₃ ), potassium hydrogen carbonate (KH
CO ₃ ), sodium carbonate (NaCO ₃ ), sodium hydrogen carbonate (NaHCO ₃ ), ammonium carbonate ((NH
₄ ) ₂ CO ₃ ), ammonium bicarbonate (NH ₄ HCO)
₃ ) and the like. The amount of the water-soluble carbonate is not particularly limited, but is generally preferably about 0.0001 to 10% by weight in the pad. 0.0001 of water-soluble carbonate
When the amount is less than 10% by weight, the effect of accelerating the polishing rate is not achieved, and practicality is lacking. On the other hand, when the amount of the water-soluble carbonate exceeds 10% by weight, the pH of water used at the time of polishing greatly increases, and mirror polishing is performed. This is not preferable because the surface roughness of the subsequent wafer deteriorates.

Specific examples of the polishing pad include a conventionally known nonwoven fabric type polishing pad, a suede type polishing pad, and a polyurethane foam type polishing pad. Since the polishing pad of the type is a hard pad, the edge portion is less likely to sag, and thus is suitable as a mirror polishing pad for a silicon wafer.

The abrasive grain ratio is preferably about 0.1 to 50% by weight. When the abrasive grain ratio is less than 0.1% by weight, the polishing rate is reduced and the practicability is lacking.
If it exceeds, the number of abrasive grains not contributing to the polishing process increases, and the strength of the polishing pad itself also decreases to shorten its useful life and increase the polishing cost. The method for manufacturing the polishing pad may be in accordance with a known manufacturing method.

[Third Polishing Method] The mirror polishing method for a silicon wafer according to the present embodiment comprises the steps of:
The silicon wafer is polished while supplying water between the silicon wafer and the polishing pad. When a silicon wafer is polished under a wet condition using this polishing pad, water-soluble carbonate in the pad is eluted, and a mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer is performed. The hindrance of side reactions can be efficiently suppressed, and as a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. Also,
Since the fine particles of alkaline earth metal carbonate are contained as abrasive grains, a mirror surface can be easily obtained without generating scratches.

As a method for mirror-polishing a silicon wafer using the polishing pad of this embodiment, a conventional wet polishing method can be used without any change. As a specific example, the load, that is, the polishing pressure is increased while supplying water between the silicon wafer attached to the wafer support and the polishing pad mounted on the surface plate of the mechanical rotary polishing apparatus. A method of polishing by applying a load can be exemplified. The polishing pressure is not particularly limited, and is usually 9.8 to 39.2 kPa (100 to 400 gf).
/ Cm ² ) is sufficient, but a larger polishing pressure is preferable because the pressure at the true contact point with the abrasive grains (alkaline earth metal fine particles) increases and the polishing rate is improved.

"Polishing liquid" The polishing liquid for mirror polishing a silicon wafer according to this embodiment is composed of an aqueous solution of a water-soluble carbonate. The concentration of the water-soluble carbonate in the polishing liquid is not particularly limited as long as the water-soluble carbonate is in a range in which the water-soluble carbonate is dissolved, but is usually in a range of 0.0001 to 10% by weight. When the concentration of the water-soluble carbonate is less than 0.0001% by weight, the effect of accelerating the polishing rate is not achieved, and the practicality is lacking. On the other hand, when the amount of the water-soluble carbonate exceeds 10% by weight, it is used for polishing. This is not preferable because the pH of water is significantly increased and the surface roughness of the wafer after mirror polishing is deteriorated.

[Fourth Polishing Method] The mirror polishing method for a silicon wafer according to this embodiment comprises the steps of:
The silicon wafer is polished while supplying the polishing liquid between a whetstone or a pad containing fine particles of alkaline earth metal carbonate as abrasive grains. That is, when a silicon wafer is polished by using the polishing liquid, a side reaction which hinders a mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer due to the presence of the water-soluble carbonate. Can be suppressed efficiently, and as a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be increased. Also, since the grindstone or pad contains fine particles of alkaline earth metal carbonate as abrasive grains, there is no occurrence of scratches,
A mirror surface can be easily obtained.

The whetstone or pad containing the alkaline earth metal carbonate fine particles as abrasive grains is not particularly limited, and may be any one containing alkaline earth metal carbonate fine particles as abrasive grains. Examples of the alkaline earth metal carbonate fine particles include barium carbonate (BaCO ₃ ) fine particles and calcium carbonate (C
ACO ₃₎ particles, magnesium carbonate (MgCO ₃₎ particles, strontium carbonate (SrCO ₃₎ can be mentioned fine particles, its particle size, in terms of polishing characteristics, 0.
Those having a diameter of about 01 to 10 μm are preferred.

As a method for polishing a silicon wafer,
The conventional wet polishing method can be performed without any change. As a specific example thereof, a silicon wafer attached to a wafer support, and a polishing whetstone or a pad mounted on a surface plate of a mechanical rotary polishing apparatus and containing alkaline earth metal carbonate fine particles as abrasive grains. In the meantime, a method of polishing by applying a load, that is, a polishing pressure while supplying water, can be exemplified. The polishing pressure is not particularly limited, and is usually from 9.8 to 39.2 kPa.
(100 to 400 gf / cm ² ) is sufficient, but the larger the polishing pressure, the higher the pressure at the true contact point with the abrasive grains (alkaline earth metal fine particles), which is preferable because the polishing rate is improved.

Hereinafter, the present invention will be described specifically with reference to Examples and Comparative Examples. "Example 1" (Preparation of slurry for polishing silicon wafer) 5 g of 500 g of calcium carbonate particles having an average primary particle diameter of 0.5 μm
After mixing and stirring with 9500 g of an aqueous solution in which potassium carbonate (1% by weight of the calcium carbonate) was dissolved, the mixture was dispersed using an ultrasonic disperser for 10 minutes to obtain a slurry for polishing a silicon wafer of Example 1.

"Polishing test" The polishing surface of a commercially available polycarbonate plate having a thickness of 5 mm was uniformly formed with fine irregularities so that the surface roughness Ra was 2 μm. After this polycarbonate plate was stuck on the platen of a mechanical rotary polishing apparatus with a double-sided tape, the flatness and flatness of the polycarbonate plate on the platen were adjusted with a # 200 diamond correction ring. . Then, while the abrasive slurry of Example 1 was supplied onto the polycarbonate plate, the polishing pressure was 19.6 kPa (200 gf / cm ² ), the number of revolutions of the platen was 60 rpm, and the amount of abrasive slurry supplied was 500 m.
l / min, polishing time: under polishing conditions of 30 minutes, diameter 100
mm (100) Si wafer was polished. This Si wafer was previously ground to a surface roughness of 20 nm using a # 2000 diamond grindstone. Table 1 shows the results of the polishing test.

The polishing rate was measured by a gravimetric method (measurement of the weight loss of the wafer before and after polishing, and conversion from the polishing time to thickness), and the surface roughness and edge sag were measured by a contact type surface roughness meter. did. Also, the presence or absence of the work-affected layer is determined by observing the cross-section of the wafer with a transmission electron microscope to determine the thickness of the affected layer, while the presence or absence of scratches is observed by an optical microscope.

Example 2 (Preparation of Silicon Wafer Polishing Slurry) 1.5 g (0.3% by weight of the calcium carbonate) of potassium hydrogen carbonate was dissolved in 500 g of the calcium carbonate particles used in Example 1. After mixing and stirring with 9500 g of the aqueous solution, the mixture was dispersed for 10 minutes using an ultrasonic disperser to obtain a slurry for polishing a silicon wafer of Example 2. (Polishing Test) The polishing test was performed in the same manner as in Example 1. However, the polishing slurry of Example 2 was used instead of the polishing slurry of Example 1. Table 1 shows the results of the polishing test.

Example 3 (Preparation of Silicon Wafer Polishing Slurry) An aqueous solution in which 0.5 g (0.1% by weight of the calcium carbonate) of ammonium carbonate was dissolved in 500 g of the calcium carbonate particles used in Example 1 After mixing and stirring to 9500 g, the mixture was dispersed using an ultrasonic disperser for 10 minutes to obtain a slurry for polishing a silicon wafer of Example 3. (Polishing Test) The polishing test was performed in the same manner as in Example 1. However, the polishing slurry of Example 3 was used instead of the polishing slurry of Example 1. Table 1 shows the results of the polishing test.

Example 4 (Preparation of Grinding Stone) Calcium carbonate 540 used in Example 1
0 g and 54 g of potassium carbonate, and 546 g of a phenol resin is added to and mixed with the mixture, and the mixture is heated by molding.
A disc-shaped grindstone having a diameter of 380 mm and a thickness of 5 mm was obtained. (Polishing Test) A polishing test was carried out according to Example 1. However, the above disk-shaped grindstone was used in place of the polycarbonate plate, and water was used in place of the polishing slurry of Example 1. The water supply is 10 ml / min. Table 1 shows the results of the polishing test.

Example 5 (Preparation of Grinding Stone) Calcium carbonate 540 used in Example 1
0 g and 600 g of a phenol resin were added and mixed, and the mixture was heated by molding to obtain a disc-shaped grindstone having a diameter of 380 mm and a thickness of 5 mm. (Adjustment of Polishing Liquid) A 1% by weight aqueous solution of potassium carbonate was prepared and used as a polishing liquid. (Polishing Test) A polishing test was carried out according to Example 1. However, the above disk-shaped grindstone was used in place of the polycarbonate plate, and the above polishing liquid was used in place of the polishing slurry of Example 1. The supply amount of the polishing liquid is 10 ml / min. Table 1 shows the results of the polishing test.

Example 6 (Production of polishing pad of foamed polyurethane type) 700 g of calcium carbonate and 7 g of potassium carbonate used in Example 1
And 7000 g of a urethane resin (Hybrene L-315, manufactured by Mitsui Toatsu Chemicals, Inc.) is mixed and dispersed in the mixture, and then Dabc is used as a blowing agent and a catalyst for polymerization.
o (Sankyo Air Products Co., Ltd.) 35 g and modified silicone oil 60 g as a foam stabilizer were added and mixed uniformly, and then a small amount of 3,3'-dichloro-4,4'diaminophenylmethane was quickly added and mixed. Injected into mold. After foaming was completed, the mold was removed and the reaction product was cured at 80 ° C. The cured product was sliced to a thickness of 3 mm to obtain a polishing pad. (Polishing Test) A polishing test was carried out according to Example 1. However, the polishing pad was used in place of the polycarbonate plate, and water was used in place of the polishing slurry of Example 1. The water supply is 10 ml / min. Table 1 shows the results of the polishing test.

Comparative Example 1 (Preparation of Silicon Wafer Polishing Slurry) After mixing and stirring 500 g of the calcium carbonate particles used in Example 1 and 9500 g of water, the mixture was dispersed for 10 minutes using an ultrasonic disperser. Thus, a silicon wafer polishing slurry of Comparative Example 1 was obtained. (Polishing Test) The polishing test was performed in the same manner as in Example 1. However, the polishing slurry of Comparative Example 1 was used instead of the polishing slurry of Example 1. Table 1 shows the results of the polishing test.

"Comparative Example 2" (Polishing Test) A polishing test was carried out in accordance with Example 1. However, a commercially available hard polishing pad IC1000 (manufactured by Rodel Nitta Co., Ltd.) was used instead of the polycarbonate plate, and the polishing slurry of Comparative Example 1 was used instead of the polishing slurry of Example 1. Table 1 shows the results of the polishing test.

Comparative Example 3 (Adjustment of Polishing Slurry) The average primary particle diameter was 0.03 μm.
m fumed silica powder (Nippon Aerosil Co., Ltd.)
Was mixed with 9500 g of water and stirred, and then adjusted to pH 10.5 by adding calcium hydroxide to obtain a polishing slurry of Comparative Example 3. (Polishing Test) A polishing test was carried out according to Example 1. However, the polishing slurry of Comparative Example 3 was used instead of the polishing slurry of Example 1. Table 1 shows the results of the polishing test.

Comparative Example 4 (Polishing Test) A polishing test was carried out in accordance with Example 1. However, a commercially available hard polishing pad SUBA800 (manufactured by Rodel Nitta Co., Ltd.) was used instead of the polycarbonate plate, and the polishing slurry of Comparative Example 3 was used instead of the polishing slurry of Example 1. Table 1 shows the results of the polishing test.

[0059]

[Table 1]

[0060]

As described above, the silicon wafer mirror polishing slurry according to the first aspect of the present invention comprises water, alkaline earth metal carbonate fine particles as abrasive grains, and water-soluble carbonate as a polishing accelerator. By at least containing, when polishing a silicon wafer using this,
Polishing of silicon wafers by efficiently suppressing side reactions that hinder the mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer, thereby increasing the rate at which the main reaction occurs The speed can be remarkably increased, and a mirror surface can be easily obtained without occurrence of scratches. In the method for mirror-polishing a silicon wafer according to claim 2, the silicon wafer mirror-polishing slurry according to claim 1 is supplied between a silicon wafer and a silicon wafer polishing plate made of a plastic plate. To polish the wafer,
Not only the polishing rate is excellent, but also the wafer shape after polishing, in particular, a highly accurate shape without edge sagging at the wafer outer peripheral portion can be obtained, and a commercially available plastic plate can be used as the polishing plate. Therefore, the mirror polishing cost can be reduced.

Further, the grinding wheel for mirror-polishing a silicon wafer according to claim 3 contains at least alkaline earth metal carbonate fine particles as abrasive grains and a water-soluble carbonate as a polishing accelerator. When a silicon wafer is polished in a wet manner while supplying water using the same, water-soluble carbonate in the grinding wheel elutes, and a mechanochemical reaction between the alkaline earth metal carbonate as abrasive grains and the silicon wafer (mainly Reaction) can be efficiently suppressed, and as a result, the rate at which the main reaction occurs increases, so that the polishing rate of the silicon wafer can be remarkably increased, and alkaline earth metal carbonate fine particles can be used as abrasive grains. , A mirror surface can be easily obtained without occurrence of scratches. The method for mirror-polishing a silicon wafer according to claim 4 is such that the silicon wafer is polished while supplying water between the silicon wafer and the grinding wheel for mirror-polishing silicon wafer according to claim 3. The polishing rate can be remarkably increased, a scratch can be prevented, and a mirror surface can be easily obtained at low cost.

The mirror polishing pad for a silicon wafer according to the fifth aspect of the present invention contains at least alkaline earth metal carbonate fine particles as abrasive grains and a water-soluble carbonate as a polishing accelerator. When a silicon wafer is polished under a wet condition while supplying water using the same, water-soluble carbonate in the pad elutes, and a mechanochemical reaction between the alkaline earth metal carbonate as abrasive grains and the silicon wafer (mainly Reaction) can be efficiently suppressed, and as a result, the rate at which the main reaction occurs can be increased, and the polishing rate of the silicon wafer can be increased. In addition, alkaline earth metal carbonate fine particles can be used as abrasive grains. Because it contains
A mirror surface can be easily obtained without generation of scratches. The method for mirror-polishing a silicon wafer according to claim 6 is such that the silicon wafer is mirror-polished while supplying water between the silicon wafer and the silicon wafer mirror-polishing pad according to claim 5. The polishing speed is remarkably improved, a mirror surface can be obtained in a short time, the throughput is further improved, and there is no generation of edge sagging, scratches, and a damaged layer, and the polishing cost is low.

The polishing liquid for mirror-polishing a silicon wafer according to claim 7 comprises an aqueous solution of a water-soluble carbonate. When the polishing liquid is used to polish a silicon wafer, the presence of the water-soluble carbonate causes It is possible to efficiently suppress the side reaction which hinders the mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as the abrasive grains and the silicon wafer, thereby increasing the rate at which the main reaction occurs, The polishing rate of the silicon wafer can be significantly increased. The method for mirror-polishing a silicon wafer according to claim 8, wherein the method for mirror-polishing a silicon wafer according to claim 7 is provided between a silicon wafer and a grindstone or a pad containing fine particles of alkaline earth metal carbonate as abrasive grains. By mirror-polishing the silicon wafer while supplying a polishing liquid, the presence of the water-soluble carbonate prevents the mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer. Side reaction can be suppressed efficiently, and as a result, the rate at which the main reaction occurs can be increased, and the polishing rate of the silicon wafer can be increased.Also, alkaline earth metal carbonate fine particles as abrasive grains in the grindstone or pad can be obtained. Since it is contained, a mirror surface can be easily obtained without occurrence of scratches.

The mirror polishing method for a silicon wafer according to the ninth aspect is characterized in that the silicon wafer is wet-polished in the presence of water and a water-soluble carbonate using alkaline earth metal carbonate fine particles as abrasive grains. When a silicon wafer is polished using this mirror polishing method, a side reaction which hinders a mechanochemical reaction (main reaction) between the alkaline earth metal carbonate as abrasive grains and the silicon wafer due to the presence of the water-soluble carbonate is caused. Efficiently suppressed, the rate at which the main reaction occurs can be increased, the polishing rate of the silicon wafer can be significantly increased, and the wafer shape after polishing,
In particular, it is possible to obtain a high-precision shape without the occurrence of edge sagging, scratch damage, and a work-affected layer on the outer peripheral portion of the wafer,
Moreover, the polishing cost is low.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B24D 3/02 310 B24D 3/02 310A C09K 3/14 550 C09K 3/14 550C 550Z H01L 21/304 621 H01L 21/304 621D 622 622D 622F F term (reference) 3C058 AA04 AA07 AA09 DA02 DA17 3C063 AA02 BB01 BD01 EE10 EE26

Claims (9)

[Claims] 1. A slurry for mirror-polishing a silicon wafer, comprising at least water, alkaline earth metal carbonate fine particles, and a water-soluble carbonate. 2. The silicon wafer is polished while supplying the silicon wafer mirror polishing slurry according to claim 1 between a silicon wafer and a silicon wafer polishing polishing plate made of a plastic plate. Mirror polishing method for wafer. 3. A grinding wheel for mirror-polishing a silicon wafer, comprising at least alkaline earth metal carbonate fine particles and a water-soluble carbonate. 4. A mirror polishing method for a silicon wafer, wherein the silicon wafer is polished while supplying water between the silicon wafer and the grinding wheel for mirror polishing the silicon wafer according to claim 3. 5. A silicon wafer mirror polishing pad comprising at least alkaline earth metal carbonate fine particles and a water-soluble carbonate. 6. A mirror polishing method for a silicon wafer, wherein the silicon wafer is polished while supplying water between the silicon wafer and the silicon wafer mirror polishing pad according to claim 5. 7. A polishing liquid for mirror polishing a silicon wafer, comprising an aqueous solution of a water-soluble carbonate. 8. A method for polishing a silicon wafer according to claim 7, wherein said polishing liquid is supplied between a silicon wafer and a whetstone or a pad containing fine particles of alkaline earth metal carbonate as abrasive grains. A mirror polishing method for a silicon wafer, characterized by polishing. 9. A method for mirror-polishing a silicon wafer, wherein the silicon wafer is wet-polished in the presence of water and a water-soluble carbonate using alkaline earth metal carbonate fine particles as abrasive grains.