JP4466312B2 - Silicon wafer polishing apparatus, silicon wafer polishing agent supply method, and silicon wafer polishing method - Google Patents

Description

  The present invention relates to a silicon wafer polishing apparatus, a silicon wafer polishing agent supply method, and a silicon wafer polishing method, and a technique for supplying the polishing agent to a polishing apparatus that performs at least two lapping steps having different roughnesses. Is.

In general, lapping of a silicon wafer after slicing is performed by sandwiching the wafer between upper and lower surface plates mainly made of Fe-based metal and moving the wafer to meteor motion. At this time, the wrapping slurry is supplied to the entire surface of the surface plate at a constant rate. The wrapping slurry is generally configured by mixing an abrasive such as alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), or silicon carbide (SiC) in pure water or a weak alkaline solvent. As this abrasive, one having a particle size of # 1000 to # 2000 is used.
Japanese Patent Laid-Open No. 61-219568

By the way, in general, when lapping, the workpiece is lapped using an abrasive having a particle size distribution corresponding to the finish roughness of the workpiece surface. For example, to reduce the surface roughness of the workpiece, an abrasive having a small average particle diameter and a narrow distribution width is used. In order to obtain such an abrasive, a high-classification technique is required, which greatly increases the cost of the abrasive and leads to an increase in wafer manufacturing costs.
Further, although abrasives of different particle sizes are stored separately, there is a demand for saving the space of the apparatus.
Furthermore, there is a possibility that abrasives of different particle sizes may be used in appropriate combinations. In such a case, it is desired to classify from abrasives having a broad particle size distribution rather than mixing them when supplying the abrasives. There was a demand to be able to supply an abrasive having a particle size distribution of.

  The present invention has been made in view of the above circumstances, and it is possible to classify by a simple method from an abrasive having a wide particle size distribution range, and to efficiently supply the abrasive after classification to the lapping process of the wafer. An object of the present invention is to provide a silicon wafer polishing agent supply method and a silicon wafer polishing apparatus.

In order to achieve the above object, the present invention employs the following configuration.
The silicon wafer polishing apparatus of the present invention is a silicon wafer polishing apparatus that performs a plurality of lapping processes for polishing a silicon wafer using abrasives of different particle sizes,
Classifying means for classifying powdered abrasives to obtain classified abrasives, slurrying means for making classified abrasives and dispersions into slurry, and supply for selectively supplying each slurry to the lapping step The above-mentioned problems have been solved by comprising an abrasive supply device having means.
The silicon wafer polishing apparatus of the present invention is a silicon wafer polishing apparatus that performs a plurality of lapping processes for polishing a silicon wafer using abrasives of different particle sizes,
A slurry having a slurry and a dispersion as a slurry, and classifying the slurry in the slurry to obtain a classified slurry, and a polishing agent selectively supplying the classified slurry to the lapping step, respectively. The above-mentioned problem was solved by comprising the supply device.
In the silicon wafer polishing apparatus of the present invention, the slurry classification means includes a separation tank that holds an abrasive and a dispersion, an agitator that stirs and mixes the abrasive and dispersion in the separation tank, and a depth of the separation tank. And a plurality of liquid inlets provided at intervals along the direction.
The silicon wafer polishing apparatus according to the present invention preferably includes a storage unit in the supply apparatus that stores the particle size distribution so that the polishing agent has a particle size distribution having at least two or more peaks in an unclassified state.
The powdered abrasive is classified into a classified abrasive, the classified abrasive and dispersion are mixed to form a slurry, and the slurry is subjected to a plurality of lapping processes for polishing silicon wafers using abrasives of different particle sizes. A method for supplying an abrasive for silicon wafers, characterized in that
The method for supplying an abrasive for a silicon wafer according to the present invention comprises mixing an abrasive and a dispersion to form a slurry, classifying the abrasive in the slurry to obtain a classified slurry, and using an abrasive having a different particle size for the silicon wafer. The classified slurry can be supplied to a plurality of lapping processes.
In the method for supplying an abrasive for silicon wafers of the present invention, the dispersion and the abrasive are put into a separation tank and stirred and mixed to form the slurry, and the polishing is performed while controlling the stirring speed and dispersed in the dispersion. A settling slurry is collected from a plurality of liquid inlets provided at intervals along the depth direction of the separation tank, and the precipitated polishing agent is collected together with the dispersion to form a classified slurry, and the silicon wafer is different. It is preferable to supply the classified slurry to a plurality of lapping processes for polishing using a grain-size abrasive.
The silicon wafer polishing method of the present invention can wrap a silicon wafer by using the classification slurry obtained by the above-described silicon wafer polishing agent supply method.

In the present invention, an unclassified abrasive, that is, an abrasive having a wide particle size distribution is stored, and an abrasive having a predetermined particle size distribution is classified from this according to the request of the lapping process, and this is classified. By enabling supply to multiple lapping processes with different conditions as a slurry, lapping can be performed under fine grain size control in each lapping process, and slurry can be supplied in accordance with the unevenness of the wafer. More precise processing is possible.
In particular, it is possible to supply # 1000 and # 2000 abrasives to the process using a coarse abrasive and the process using a fine abrasive, respectively. It is not necessary to prepare # 1000 abrasives separately, thereby reducing the manufacturing cost and eliminating the need to store these abrasives separately, thereby reducing the space required for the apparatus. .

The apparatus for supplying an abrasive for a silicon wafer according to the present invention comprises a classifying means for classifying a powdered abrasive into a classified abrasive, a slurrying means for adding a dispersion to the classified abrasive to form a slurry, It is characterized by comprising supply means for supplying the slurry to the lapping process of the silicon wafer.
The apparatus for supplying an abrasive for a silicon wafer according to the present invention comprises a slurry classification means for adding a dispersion to an abrasive to form a slurry, classifying the abrasive in the slurry to obtain a classified slurry, and the classified slurry. It is characterized by comprising supply means for supplying a silicon wafer lapping process.

  According to the above supply device, classification can be performed by a simple method from an abrasive having a wide particle size distribution range, and the classified abrasive can be efficiently supplied to the lapping process of the wafer.

  An apparatus for supplying an abrasive for a silicon wafer according to the present invention is the supply apparatus described above, wherein the slurry classification means includes a separation tank for holding an abrasive and a dispersion, and an abrasive and dispersion in the separation tank. It is characterized by comprising a stirrer for stirring and mixing and a plurality of liquid inlets provided at intervals along the depth direction of the separation tank.

  According to the above supply device, the dispersion liquid and the abrasive are put into the separation tank and mixed by stirring, and the abrasive dispersed in the dispersion is allowed to settle while controlling the stirring speed, and a plurality of liquid inlets From the above, the settled abrasive can be collected together with the dispersion to form a classified slurry, and this classified slurry can be supplied to the lapping process of the silicon wafer. From each of the plurality of liquid collection ports, classified slurries containing abrasive particles having different average particle diameters and distribution widths are obtained. By supplying the classified slurry thus obtained to the silicon wafer lapping step in order from the one having the largest average particle diameter, the silicon wafer can be efficiently lapped.

  A silicon wafer polishing apparatus according to the present invention includes any one of the above-described supply apparatuses.

Next, according to the method for supplying the abrasive for silicon wafers of the present invention, a powdery abrasive is classified into a classified abrasive, a dispersion is added to the classified abrasive to form a slurry, and the slurry is added to the silicon wafer. It supplies to a lapping process, It is characterized by the above-mentioned.
Further, the method for supplying the abrasive for a silicon wafer according to the present invention comprises adding a dispersion to the abrasive to form a slurry, classifying the abrasive in the slurry to obtain a classified slurry, and wrapping the classified slurry to a silicon wafer It is characterized by supplying to.

  According to the above supply method, classification can be performed by a simple method from an abrasive having a wide particle size distribution range, and the classified abrasive can be efficiently supplied to the lapping process of the wafer.

  Further, the silicon wafer polishing agent supply method of the present invention is the above-described supply method, wherein the dispersion liquid and the polishing agent are put into a separation tank and stirred to form the slurry, while the stirring speed is controlled while the slurry is controlled. The abrasive dispersed in the dispersion is allowed to settle, and the precipitated abrasive is collected together with the dispersion from each of a plurality of liquid inlets provided at intervals along the depth direction of the separation tank. The classified slurry is supplied to the silicon wafer lapping step.

  The silicon wafer polishing method of the present invention is characterized in that the silicon wafer is lapped using the classification slurry obtained by any one of the above-described supply methods.

  As described above, according to the silicon wafer polishing agent supply method and silicon wafer polishing agent supply apparatus of the present invention, classification is performed by a simple method from an abrasive having a wide particle size distribution range. The abrasive can be efficiently supplied to the lapping process of the wafer.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic diagram showing a configuration of a polishing agent supply device in the silicon wafer polishing apparatus of the present embodiment. FIG. 2 is a schematic diagram showing a main part of the silicon wafer polishing agent supply device. 3 is a schematic view showing the particle size distribution of the abrasive in each step.
A silicon wafer polishing agent supply apparatus 1 shown in FIG. 1 (hereinafter simply referred to as a supply apparatus) includes a separation tank 2 and a stirrer 3 constituting slurry classification means, and a supply pipe (supply path) constituting supply means. 4a, 4b and 4c.

The separation tank 2 is a container for charging and mixing the dispersion solution and the abrasive and setting the abrasive particles. The separation tank 2 includes a dispersion supply pipe 5 and an abrasive supply pipe 6. And are attached. Further, a hopper (storage means) 7 for storing the abrasive is provided upstream of the abrasive supply pipe 6.
The stirrer 3 stirs and mixes the contents in the separation tank 2 (mixture of dispersion solution and abrasive), and has a stirring blade 3a attached to the tip.

  Further, the supply pipes 4a, 4b, and 4c are pipes extending from the separation tank 2, and the contents in the separation tank 2 can be supplied to the silicon wafer lapping devices 8a, 8b, and 8c. The lapping devices 8a, 8b, and 8c are for lapping both front and back surfaces of a silicon wafer cut out from a silicon pulling ingot. The lapping device 8a has a relatively large lapping amount, and the lapping device 8b is more than the device 8a. The wrapping amount is small, and the wrapping device 8c has a smaller wrapping amount than the device 8b.

  Thus, the surface roughness of the front and back surfaces of the silicon wafer can be reduced by sequentially lapping the wafers by the devices 8a, 8b and 8c having different wrap amounts. Therefore, as shown in FIG. 3, the abrasive supplied to the wrapping device 8a is supplied with a larger particle size than the device 8b, and the abrasive supplied to the wrapping device 8b is larger in particle size than the device 8c. Is to be supplied. Specifically, the abrasives supplied to the wrapping apparatuses 8a, 8b, and 8c can be configured so that the average particle diameters are # 1000, # 1500, and # 2000, respectively. In FIG. 3, the graph showing the particle size distribution is shown so that the particle size decreases from the right side to the left side. In FIG. 3, it is assumed that the wafer W is processed in the order of the wrapping apparatuses 8a, 8b, and 8c.

As shown in FIG. 2, supply pipes 4 a, 4 b, and 4 c are inserted into the separation tank 2. An opening that is inclined with respect to the longitudinal direction is provided at the tip of the supply pipes 4a, 4b, and 4c, and the openings serve as liquid intake ports 14a, 14b, and 14c. The liquid inlets 14 a, 14 b, and 14 c are arranged in stages along the depth direction of the separation tank 2. That is, the intake port 14a is disposed in the lower part of the separation tank 2, the intake port 14c is disposed in the upper part of the separation tank 2, and the intake port 14b is located between the intake ports 14a and 14b.
Further, the intake ports 14a, 14b, and 14c are inclined with respect to the longitudinal direction of the supply pipes 4a, 4b, and 4c, so that the intake ports 14a, 14b, and 14c have a certain amount along the depth direction of the separation tank 2. It has a width.

Next, a method for supplying a silicon wafer abrasive will be described.
First, an abrasive and a dispersion solution are charged into the separation tank 2 to form a slurry. For example, a powder of alumina (Al ₂ O ₃ ), zirconia (ZrO ₂ ), silicon carbide (SiC), or the like is used as the abrasive. The average particle size of the abrasive stored in the hopper 7 is preferably in the range of 1 μm to 25 μm. Further, the particle size of 5% integrated from the smaller particle size of the abrasive particles is in the range of 1 μm to 5 μm, and the particle size of 95% integrated from the smaller particle size is from 15 μm to 25 μm. What is the following ranges is preferable.
Further, as the dispersion solution, for example, pure water or a weak alkaline solvent is preferable. The input ratio of the abrasive and the dispersion is preferably in the range of, for example, abrasive: dispersion = 5: 1 to 10: 1 in terms of mass ratio.

  When the polishing agent and the dispersion solution are put into the separation tank 2, the stirrer 3 is operated to stir and mix the polishing agent and the dispersion solution. After thorough mixing, the stirring speed is controlled to allow the abrasive particles to settle in the dispersion solution. The stirring speed at this time is preferably set so that the flow rate of the dispersion solution in the vicinity of the side wall surface of the separation tank 2 is in the range of about 0.1 to 0.3 m / s. When the abrasive is precipitated in the dispersion, the abrasive particles having a larger particle size tend to settle faster, and the abrasive particles having a smaller particle size tend to settle slower. Thereby, abrasive particles having a small particle size are distributed in the upper part of the separation tank 2, and abrasive particles having a large particle size are distributed in the lower part of the separation tank 2. Thus, the particle size distribution of the abrasive particles is generated along the depth direction of the separation tank 2.

Next, abrasive particles are collected together with the dispersion solution from the liquid inlets 14a to 14c arranged at intervals along the depth direction of the separation tank 2. In each of the liquid inlets 14a to 14c, a dispersion liquid containing abrasive particles having a narrower particle size distribution width than the first charged abrasive is obtained.
Further, since the classified slurry supplied through the supply pipe 4a is collected from the liquid inlet 14a installed at the bottom of the separation tank 2, the average particle size of the abrasive particles is the same as that of the original abrasive. It becomes larger than the average particle diameter. Further, since the classified slurry supplied through the supply pipe 4c is collected from the liquid inlet 14c installed at the bottom of the separation tank 2, the average particle size of the abrasive particles is the average of the original abrasive. Smaller than particle size. Further, since the classified slurry supplied through the supply pipe 4b is collected from the liquid inlet 14b installed between the liquid inlets 14a and 14c, the average particle diameter of the abrasive particles is the original. The average particle size of the abrasive is approximately the same.
Specifically, the classified slurry supplied through the supply pipe 4a preferably contains abrasive particles having a particle size of 10 μm or more, and the classified slurry supplied through the supply pipe 4b has a particle size of more than 6 μm and less than 10 μm. The abrasive particles are desirably included, and the classified slurry supplied through the supply pipe 4c preferably includes abrasive particles having a particle size of 6 μm or less. The range of the particle size of the abrasive particles contained in each classified slurry is the particle size distribution of the abrasive to be introduced, the ratio of the abrasive and the dispersion, the depth and internal volume of the separation tank, the stirring speed, and the position of the liquid inlet , Etc., as appropriate.

  Dispersions containing abrasive particles collected at the respective liquid inlets 14a to 14c are supplied to silicon wafer wrapping apparatuses 8a to 8c through supply pipes 4a to 4c as classified slurry. Since the classified slurry supplied through each of the supply pipes 4a to 4c includes abrasive particles having an average particle diameter as described above, the silicon wafers are sequentially ordered in descending order of the average particle diameter of the abrasive particles. By supplying to the lapping process, the silicon wafer can be efficiently lapped.

Prepare a supply device as shown in FIG. 1 and FIG. 2, put the abrasive and dispersion into the separation tank, operate the stirrer to stir and mix the abrasive and dispersion, mix thoroughly, and then stir The abrasive particles were allowed to settle in the dispersion solution at a controlled rate. Then, abrasive particles were collected together with the dispersion solution from three liquid inlets arranged at intervals along the depth direction of the separation tank. The particle size distribution of the abrasive in the dispersion after collection was measured. The results are shown in Table 1.
The abrasive used was an Al ₂ O ₃ powder with a specific gravity of 4 g / cm ³ , an average particle size of 8 μm, and a particle size of 5 μm, which is 5% from the smaller particle size. The particle diameter is 95 μm integrated from the smaller one of 15 μm. As the dispersion, a surfactant mixture having a specific gravity of 1.1 g / cm ³ and a viscosity of 31 cP was used. Furthermore, the operating conditions of the supply device are also shown in Table 1. In addition, the attachment position of the water intake in Table 1 means that the opening is opened at a depth of 0.5 to 1.5 m from the upper end of the tank in the case of the upper water intake of Example 1, for example.

  As shown in Table 1, it can be seen that the average particle size of the abrasive particles contained in the classified slurry can be changed by appropriately setting the operating conditions of the supply device.

  The present invention is not limited to the above embodiment, and various modifications may be made. Examples of the classification means in the present invention include known dry classification means such as a multistage knitted dry cyclone, a sieving device, and a centrifugal classifier. Further, as the slurrying means in the present invention, a known stirring device comprising a stirring tank and a stirrer can be used.

It is a schematic diagram which shows the structure of the supply apparatus of the abrasive | polishing agent for silicon wafers which is embodiment of this invention. It is a schematic diagram which shows the principal part of the supply apparatus of the abrasive | polishing agent for silicon wafers which is embodiment of this invention. It is a schematic diagram which shows the lapping process and the particle size of an abrasive | polishing agent in the polishing apparatus for silicon wafers which is embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Supply apparatus of the abrasive | polishing agent for silicon wafers, 2 ... Separation tank, 3 ... Stirrer, 4a, 4b, 4c ... Supply piping (supply path), 7 ... Hopper (storage means), 14a, 14b, 14c ... Intake port

Claims (4)

A silicon wafer polishing apparatus that performs a plurality of lapping processes for polishing silicon wafers using abrasives of different particle sizes,
Slurry classification means which makes an abrasive and a dispersion into a slurry, classifies the abrasive in the slurry to give a classified slurry, and a supply means which selectively supplies the classified slurry to the lapping step. Comprising an abrasive supply device,
The slurry classifying means, arranged spaced and separation tank that holds the abrasive and the dispersion liquid, a stirrer for mixing stirring the abrasives and dispersion of the separation tank, the distance along the depth direction of the separation tank A plurality of liquid inlets, and the liquid inlet is an opening provided at the tip of the supply pipe and inclined with respect to the longitudinal direction of the supply pipe, and each liquid inlet has a depth of the separation tank. A polishing apparatus for a silicon wafer, characterized by having a shape having a width along a direction.   2. The polishing apparatus for a silicon wafer according to claim 1, wherein the supply apparatus has storage means for storing the abrasive so as to have a particle size distribution having at least two or more peaks in an unclassified state. . An abrasive and a dispersion are mixed to form a slurry, and the abrasive in the slurry is classified to give a classified slurry, and the classified slurry is applied to a plurality of lapping processes for polishing a silicon wafer with an abrasive having different particle sizes. When supplying
A separation tank for holding the abrasive and the dispersion liquid, wherein the stirrer the abrasive and the dispersion in the separation tank for mixing and stirring, a plurality of Toeki port provided at intervals along the depth direction of the separation tank The liquid inlet is an opening provided at the tip of the supply pipe and inclined with respect to the longitudinal direction of the supply pipe, and each liquid inlet is in the depth direction of the separation tank. A shape with a width along,
The dispersion liquid and the abrasive are put into the separation tank and stirred and mixed to form the slurry, and the abrasive dispersed in the dispersion liquid is allowed to settle while controlling the stirring speed, and the depth direction of the separation tank Each of a plurality of liquid inlets provided at intervals along the surface of the slurry is collected together with the dispersion liquid to form a classified slurry, and a plurality of polishing silicon wafers using abrasives of different particle sizes A method for supplying an abrasive for a silicon wafer, comprising supplying the classified slurry to a lapping step.   A method for polishing a silicon wafer, comprising lapping a silicon wafer using the classification slurry obtained by the supply method according to claim 3.

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