JP2001291690A - Apparatus and method for polishing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing apparatus and a polishing method for mirror surface polishing a work (wafer) with high efficiency and accuracy, a novel board for holding a work efficiently, and a method for bonding a work to the work holding board with high accuracy. SOLUTION: The polishing apparatus 28 comprises a turntable 29, and a work holding board 38 and polishes a work W held by the work holding board 38, while supplying polishing agent solution, where the variations in the turntable 29 in the direction normal to the surface thereof and/or variations in the work holding board 38 in the direction normal to the work holding surface thereof is limited to 100 μm or smaller at polishing operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus, a polishing method, and a work (for example, a wafer, etc.) that enable high-efficiency, high-precision mirror finishing of a work, for example, a silicon wafer (sometimes simply referred to as a wafer). The present invention relates to a novel work holding plate for efficiently holding and a method of bonding a work to the work holding plate.

[0002]

[Related Art] Reflecting the increase in diameter of silicon wafers and the increase in precision of devices manufactured using the same, the finishing accuracy (thickness uniformity, flatness, The demand for smoothness) is becoming increasingly sophisticated.

[0003] In order to satisfy such demands, the polishing technique of the wafer has been improved, and a polishing apparatus has been developed and improved.

As one of them, a so-called single-wafer polishing apparatus has been newly developed, particularly for polishing a large diameter wafer having a diameter of 300 mm or more, and a part thereof has been put to practical use.

However, it is difficult for the single wafer polishing method to cope with the demand for reducing the cost of the wafer in terms of productivity, and it is not possible to sufficiently cope with the recent demand for the flatness near the wafer periphery (within 2 mm). And other problems have arisen.

On the other hand, in a conventional batch type polishing apparatus for simultaneously polishing a plurality of wafers, a rotary shaft 17 is used as shown in FIG. A work holding plate on which one or more wafers W are rotated by a rotating shaft 18 by means such as bonding on the surface of a polishing cloth 16 attached to the upper surface of a polishing platen 10 rotated at a predetermined rotation speed. 13 and presses the surface to be polished of the wafer with a predetermined load by using, for example, an upper load 15, and at the same time a predetermined flow rate through a polishing agent supply pipe 14 from a polishing agent supply device (not shown). An abrasive solution (hereinafter, sometimes referred to as a slurry) 19 is supplied onto the polishing cloth 16, and the surface to be polished of the wafer W is polished through the abrasive solution 19 to the surface of the polishing cloth 16. Polishing of rubbing has been wafer W is carried out.

[0007] This batch type polishing apparatus becomes large in size as the diameter of the wafer becomes larger, the polishing platen and the work holding plate bend due to their own weight and the polishing pressure, and in addition to the thermal deformation caused by the heat generated by the polishing, furthermore, It is difficult to satisfy the requirements for the accuracy of the finished surface of the wafer because the accuracy of the finished surface of the wafer is affected by the deformation and fluctuation of the polishing surface plate and the work holding plate due to various mechanical shakes when rotating It is becoming.

[0008] In order to cope with such problems, various ingenuity have been devised regarding the structure and material of the polishing apparatus, and the operating conditions and polishing conditions of the polishing apparatus. For example, in order to prevent the thermal deformation of the structure of the apparatus, particularly (a) the polishing platen, as shown in FIG.
The lower surface plate 23 provided with a number of recesses 21 for circulating the cooling water H is separately provided on the back surface of the upper surface plate 12 to which is attached, and a rib is provided on the back surface of the surface plate to prevent deformation due to polishing pressure. In order to effectively perform the provision and the suppression of the thermal deformation, for example, as disclosed in JP-A-7-52034 and JP-A-10-296719, the polishing platen structure and the arrangement of the cooling water flow channel are devised. It has been done.

However, the conventional polishing platen 1 shown in FIG.
In the case of No. 0, for example, a structure is used in which the upper platen 12 is made of SUS410, and the lower platen 23 made of cast steel, such as FC-30, provided with a cooling water flow passage, is fastened up and down with fasteners 11 or the like. Since the temperature difference between the upper and lower surfaces of the upper platen during the polishing operation is 3 ° C. or more in the conventional polishing method, and 5 ° C. or more in many cases, the upper surface of the upper platen has a temperature difference between the upper and lower surfaces. When there is no upper surface, the height difference (deformation) in the vertical direction of 100 μm or more may occur in some places with the upper surface as a reference surface.

(B) Use of a material having a small coefficient of thermal expansion (8 × 10 ⁻⁶ / ° C.) for the polishing platen material (WO9)
No. 4,138,847), a polishing platen having an integral structure in which a cooling water circulation flow path is provided over almost the entire area using ceramics (Japanese Utility Model Laid-Open No. 59-151655), and (c) a work. Similarly, for the holding plate, a temperature control fluid is circulated inside the holding plate for the purpose of improving the temperature uniformity of the wafer holding surface (Japanese Patent Laid-Open No. 9-2959).
No. 1) has been proposed.

Further, in order to suppress the temperature rise of the wafer and the polishing cloth due to the heat generated by the polishing action, in addition to the cooling of the work holding plate and the polishing platen, an abrasive directly supplied to the polishing surface. The solution (usually a weakly alkaline aqueous solution of colloidal silica is used) is also provided with a cooling function, and supplies an amount more than the amount required for pure polishing onto the polishing cloth, and the abrasive discharged from the polishing portion The solution has been circulated for cost reduction.

However, in the configuration of the conventional polishing apparatus and the cooling method as described above, the temperature of the polishing cloth surface during polishing gradually increases from the start of polishing, and especially in a portion rubbed with the surface to be polished of the wafer. Usually reaches 10 ° C or higher,
The temperature of the upper surface portion of the polishing platen immediately below that portion also rises by 3 ° C. or more.

On the other hand, the temperature of the lower surface of the surface plate also has the effect of suppressing the temperature rise by the cooling water, and the temperature change is suppressed within 1 ° C. Therefore, a temperature difference of at least 3 ° C. is generated not only between the upper surface and the lower surface of the polishing platen but also between the high temperature portion and the low temperature portion of the upper surface of the polishing platen. In the case where there is no temperature difference, there is a portion which is deformed and displaced by 100 μm or more in the normal direction of the surface.

Further, the work holding plate is also increased in size in response to the increase in the diameter of the silicon wafer. For example, the diameter of a work holding plate for polishing an 8-inch diameter wafer is about 600 mm, and the weight of the work holding plate is accordingly increased. Has also increased.

Therefore, not only thermal deformation of the work holding plate due to heat generation on the polished surface but also deformation at the time of polishing due to its own weight becomes a problem. Attempts have been made to reduce the amount of deformation using a material having a large longitudinal elastic modulus such as (silicon carbide, alumina).

In the conventional batch type polishing, for example, as shown in FIG. 21, a method of bonding a wafer W to be polished to a work bonding surface 20a of a work holding plate 20 via an adhesive 22 has been used. Was.

At this time, it is important to prevent air from remaining in the adhesive 22 layer or at the interface between the wafer or the work holding plate 20 and the adhesive 22. For this purpose, as shown in FIG. 21, an airbag 27 provided on the lower surface of the pressurizing head 25 so as to be convexly curved downward is pressed by the pressurizing cylinder 26 onto the upper surface of the wafer W (the side opposite to the surface to be bonded). Surface), and sequentially presses the work holding plate from the center of the surface to be bonded to the peripheral edge of the wafer, thereby extruding the air at the bonding site toward the outer peripheral edge of the wafer. However, the air in the boundary layer between the wafer W and the work holding plate is pushed out by such a pressing method by the wafer pressing member 24, while the thickness of the adhesive layer 22 tends to be thinner at the central portion of the wafer. However, there is a disadvantage that the wafer W is bonded in a bent state.

Conventionally, adhesives used for bonding wafers are considered to have factors such as resistance to an abrasive solution during polishing, non-lubricating properties, and a change in characteristics due to an increase in the temperature of the adhesive due to a rise in the temperature of the wafer due to heat generated by polishing. Natural rosin, synthetic rosin ester, beeswax, phenolic resin, etc. have been used, but the adhesive action of this kind of adhesive mainly depends on the physical adhesive mechanism, and the adhesive is performed as follows. . That is, after dissolving the adhesive in the solvent and applying it to the adhesive surface,
After evaporating and removing the solvent, the wafer is pressed against the work holding plate at a predetermined pressure while keeping the adhesive in a softened and molten state by heating, and then cooled to room temperature, whereby the adhesive is solidified and bonded.

As described above, in the bonding step, it is necessary to heat the wafer and the work holding plate to, for example, 50 to 100 ° C. At this time, the deformation of the wafer and the work holding plate due to the heat history impairs the improvement of the processing accuracy. You. Also,
Therefore, there is a problem in terms of cost, such as the necessity of special equipment and energy.

On the other hand, an existing so-called room temperature adhesive capable of realizing an adhesive action at room temperature has a resistance to an abrasive solution, difficulty in peeling a wafer from a work holding plate and removing an adhesive from a wafer and a work holding plate. Therefore, practical use was impossible.

Further, in order to prevent air bubbles from remaining in the adhesive layer at the bonding site, the wafer is inclined with respect to the work holding surface with the surface to be bonded inclined with respect to the work holding surface. The method of pressing against the holding plate and removing the air interposed between the wafer bonding surface and the work holding surface from one end of the wafer bonding surface to the other end and bonding the wafers together as shown in FIG. As shown in the drawing, a method of extruding air outward by pressing the wafer W sequentially from the center of the wafer by an elastic body (airbag) 27 having a convex shape from the upper surface of the wafer W disposed on the work holding plate 20, and Is the work holding plate 20 as shown in FIG.
Means have been implemented in which the holding surface is bent so as to maintain airtightness, and the inside of the holding surface is depressurized so that no air remains.

In FIG. 22, 1 is a vacuum container, 2 is a bellows, 3 is a bellows raising / lowering cylinder, 4 is a bellows internal pressure adjusting pipe, 5 is a vacuum vessel internal pressure adjusting pipe, 6 is a vacuum suction pipe, and 20 is a work. The holding plate and W are wafers.

The method of sequentially pressing a part of the surface to be bonded of the wafer shown in FIG. 21 onto the work holding plate has a disadvantage that the thickness of the adhesive layer becomes uneven (0.5 μm or more).
The method of bonding the wafer or the entire work holding plate in a reduced pressure state shown in FIG. 2 requires a special device and jig,
This complicates the process and generates dust from equipment and jigs.

[0024]

As described above, in polishing and finishing a wafer, a polishing apparatus, in particular, a work holding plate for directly holding a wafer to be processed and a polishing cloth in contact with the wafer are attached. Achieving high-precision finishing that is compatible with the advancement of device manufacturing technology, now and in the future, in the method of bonding a wafer to a work holding plate, as well as deformation due to various causes of the polishing platen and fluctuations during equipment operation. There are a variety of factors that can be obstacles.

In order to stably and efficiently produce high-precision polished wafers, particularly large-diameter high-precision wafers having a diameter of 300 mm or more, the present inventors have developed not only the structure, configuration, and material of the polishing apparatus, but also In all processes related to wafer polishing, including the wafer bonding device and bonding method, we thoroughly investigate the factors that hinder high-precision processing, and prototype equipment,
As a result of conducting an experimental study on the system configuration and operating conditions, etc., the overall function and performance of not only the wafer bonding method but also the polishing equipment have been enhanced, and the operating method has been fundamentally improved. We succeeded in producing highly accurate polished wafers stably.

Above all, a polishing cloth is stuck for polishing a wafer with high precision (high flatness), and a polishing platen as a base for holding the shape of the polishing cloth or a work as a base for holding the wafer. It has been found that deformation of the holding plate during the polishing operation is a major obstacle, and the amount of deformation is determined for the upper surface of the polishing platen and the work holding surface of the work holding plate in the normal direction of those surfaces. It has been found that it is effective to perform polishing so that the deformation amount is kept at 100 μm, preferably 30 μm or less, more preferably 10 μm or less.

The present invention relates to a polishing apparatus, a polishing method, and a polishing method which enable highly efficient and high-precision mirror finishing of a work (wafer or the like).
It is an object of the present invention to provide a novel work holding plate that efficiently holds a work and a method of bonding a work that can bond the work to the work holding plate with high accuracy.

[0028]

According to a first aspect of the present invention, there is provided a polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held by the work holding plate. A polishing apparatus for polishing while flowing an agent solution, the amount of deformation in the direction normal to the surface of the surface plate of the polishing platen and / or the amount of deformation in the direction normal to the work holding surface of the work holding plate during the polishing operation. Is suppressed to 100 μm or less.
It is more preferable that these deformations are suppressed to 30 μm or less.

A second aspect of the polishing apparatus of the present invention is a polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held on the work holding plate while flowing an abrasive solution. A polishing platen is integrally formed by casting, and the structure of the polishing platen has a plurality of concave portions and / or ribs on a back surface, and forms a flow path of a temperature adjusting fluid inside the platen, and forms the flow path. The portion not formed is characterized by acting as an internal rib structure.

In other words, the polishing apparatus of the present invention has a concave and / or rib on the back surface of the platen and the integral and flow path of the temperature adjusting fluid, which is one of the great features of the polishing apparatus, and also has an internal rib structure inside the platen. The structure is as follows: (1) A structure in which the upper platen 12 and the lower platen 13 illustrated in FIGS. 16 and 17 which have been conventionally used are fastened with the fastener 11, or a two-layer structure disclosed in Japanese Patent Application Laid-Open No. 10-296619. The strength is higher than that of the board, and the deformation due to thermal deformation and cooling water pressure can be suppressed low. (2) Accordingly, the entire surface plate can be made thinner and lighter. (3) There is no secular change such as loosening of fasteners. (4) Since there is no need for a fastening point, the flow path of the cooling (temperature adjustment) fluid can be widely arranged, and the heat transfer area can be increased and the pressure loss due to the flow path can be reduced, so that a large amount of fluid can be flowed. Possible, and the cooling effect is greatly improved. (5) Since the thickness of the surface plate can be reduced, the distance from the surface of the surface plate to the cooling water flow path can be reduced, and the cooling effect can be further improved. The displacement of the upper surface of the surface plate with respect to the reference surface is 100 μm or less at an arbitrary point, and 30 μm or less by adopting various configurations of the present invention described below.
In an ideal state, it can be suppressed to 10 μm or less.

The value of the coefficient of thermal expansion of the material of the polishing platen is as follows:
It is preferably at most 5 × 10 ⁻⁶ / ° C., and its corrosion resistance is almost equal to that of stainless steel.

As the material for the polishing platen, invar,
That is, a stainless steel invar material which is cast steel, for example, SL
When E-20A (manufactured by Shimpo Kokutei Co., Ltd.) is used, the coefficient of thermal expansion (α = 2.5 × 10 ⁻⁶ / ° C., α is the coefficient of linear expansion) is SUS.
410 (α = 1.03 × 10 ⁻⁵ / ° C.)
4, a deformation of 30 μm or less can be realized. Further, by manufacturing the polishing surface plate by casting the cast steel in this manner, an integrated structure is made possible, and the precision finishing of the surface surface plate thereafter becomes easy.

A polishing apparatus according to a third aspect of the present invention is a polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held on the work holding plate. And / or controlling the temperature to control the temperature change of the polishing platen and / or the temperature change of the work holding plate during the polishing operation within a predetermined range.

During the above-mentioned polishing operation, the temperature fluctuation at an arbitrary position of the polishing platen and / or the work holding plate is 3
The temperature is preferably within the range of 2 ° C. In order to achieve this object, the polishing platen having an integral structure in which a temperature control fluid flow path is formed inside can greatly increase the contact area between the temperature control fluid and the platen as described above. It is valid.

Further, when polishing, the temperature and / or flow rate of the above-mentioned abrasive solution is controlled so that the temperature fluctuation at an arbitrary position on the polishing surface of the polishing cloth during the polishing operation is 10 ° C. or less, preferably 5 ° C. or less. It is preferable to control the temperature to not more than ° C.

That is, under normal conditions for achieving a predetermined polishing rate (0.5 to 1.0 μm / min) by a conventional polishing apparatus, the temperature of the polishing cloth surface is reduced by the heat generated by the polishing action. The value of the temperature change exceeds 10 ° C. in a portion that rises and particularly rubs against the surface to be polished, but the polishing platen during the polishing operation, or the work holding plate, or both, which is the basic principle of the present invention. Temperature change (fluctuation)
In order to suppress the deformation amount within 3 ° C. and to reduce the deformation amount in the normal direction of the upper surface of the polishing platen or the holding surface of the work holding plate to 100 μm or less, preferably 30 μm or less, more preferably 10 μm or less. It is important that the temperature change of the surface of the polishing cloth and the wafer, which are heat generating parts during polishing, be 10 ° C. or less, preferably 5 ° C. or less.

In actual polishing, as described above, a polishing cloth most suitable for the purpose and conditions of polishing is selected and adhered to the upper surface of the polishing platen, and between the polishing cloth and the surface to be polished of the wafer. While supplying the abrasive solution, the two are rubbed by relative motion while pressing them with a predetermined force. Generally, the thermal conductivity of the polishing cloth is the same as the thermal conductivity of silicon, the polishing platen, or the material of the work holding plate. Indicates a value that is 1 to 3 digits lower than the value. Usually, the thickness of the polishing cloth is 1 to 2 mm, and the distance (10 to 50 mm) between the upper surface of the polishing platen and the fluid flow path for temperature adjustment, and the distance between the work holding surface of the work holding board and the fluid flow path for temperature adjustment. Since the thermal resistance from the polishing cloth surface through the polishing cloth to the upper surface of the polishing platen becomes maximum as compared with the heat transfer distance (10 to 30 mm), the temperature change during the polishing operation of the polishing cloth surface temperature is preferably 10 ° C. If the temperature is controlled to a value as low as 5 ° C. or less as low as possible, the temperature change during the polishing operation of the upper surface of the polishing platen or the work holding surface of the work holding plate can be suppressed to 3 ° C., preferably 2 ° C. or less.

At this time, it is important that the polishing surface plate or the work holding plate be effectively cooled by the temperature adjusting fluid, and it is necessary to positively utilize the cooling effect of the abrasive solution.

In the above-mentioned polishing apparatus and its operation (polishing), the polishing platen, the work holding plate and the abrasive solution, which are members directly involved in the polishing action, are important requirements for realizing the basic idea of the present invention. As described above, in order to effectively realize these, factors relating to the mechanism and control of the polishing apparatus are also extremely important. That is, it is necessary that the accuracy of the mechanical fluctuation and the temperature control accompanying the driving (rotation) of the polishing platen meet a certain level, and the specific configuration thereof will be described below.

It is preferable to suppress the rotation unevenness of the polishing platen to 1% or less. The rotation unevenness of the polishing table means a ratio of a change in the number of rotations of the polishing table during the polishing operation to a set value.

It is preferable to suppress the surface runout of the polishing surface of the polishing platen during rotation to 15 μm or less. The surface deviation of the polished surface of the lapping surface when the lapping surface is rotated means a change in a substantially vertical direction at an arbitrary position on the polished surface of the lapping surface during the polishing operation.

The rotational deviation of the rotating shaft of the polishing platen is 30 μm.
m or less. Rotational deviation of the rotation axis of the polishing table means a substantially horizontal variation at an arbitrary position of the rotation axis of the polishing table during the polishing operation. In addition, the above-mentioned rotation unevenness of the polishing platen, the surface fluctuation at the time of rotation of the polishing surface of the polishing platen, and the rotational deviation of the rotating shaft of the polishing platen are all improved by improving the accuracy of the rotation system of the polishing platen. It is achievable.

It is preferable that the work holding plate has a concave portion on the back surface or has a rib structure. As described above, the work holding plate also has a concave portion formed on the back surface of the polishing platen or has a rib structure in the same manner as the polishing platen to maintain the strength and reduce the weight. Can be used as

As described above, in the polishing apparatus, the work holding plate does not merely hold the work physically but also plays an important factor in achieving the object of the present invention. It is important to suppress deformation at the time. Therefore, taking into account the values of mechanical strength and thermal conductivity, workability, wafer adhesion and even economics,
It is preferable to use a ceramic material, in particular, alumina or silicon carbide (abbreviated as SiC).

As a method of holding the wafer on the work holding plate, a method of sucking and holding the wafer on the work holding surface of the work holding plate other than by using an adhesive is used. It is useful to use a structure in which a plurality of pores for holding the workpiece by suction are opened.

The first aspect of the polishing method of the present invention is a polishing method for polishing a work held on a work holding plate having a polishing surface plate and a work holding plate, wherein the polishing surface plate during a polishing operation is provided. The amount of deformation in the direction normal to the surface of the platen and / or the amount of deformation in the direction normal to the work holding surface of the work holding plate is 10
It is characterized by being suppressed to 0 μm or less. It is more preferable that these deformations are suppressed to 30 μm or less.

A second aspect of the polishing method according to the present invention is a polishing method comprising a polishing surface plate and a work holding plate for polishing a work held on the work holding plate while flowing an abrasive solution. When the surface to be polished of the work is polished by the polishing cloth stuck on the board, a change in temperature at an arbitrary position on the polishing surface of the polishing cloth during the polishing operation is reduced by 10 ° C.
It is characterized as follows. Preferably, the fluctuation is 5 ° C. or less.

A third aspect of the polishing method of the present invention is a polishing method for polishing a work held on a work holding plate having a polishing surface plate and a work holding plate while flowing an abrasive solution. The temperature fluctuation of the work is suppressed to 10 ° C. or less. Preferably the fluctuation is 5 ° C
It is preferable to suppress the following.

Variations in temperature and / or wafer temperature at an arbitrary position on the polishing surface of the polishing cloth during the above-mentioned polishing operation are controlled by controlling the temperature and / or flow rate of the abrasive solution to 10 ° C.
Hereinafter, controlling the temperature to preferably 5 ° C. or less is an important embodiment of the present invention.

A fourth aspect of the polishing method according to the present invention is a polishing method using a polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held on the work holding plate, comprising: The relation of the following formula (1) is set to 2 mm
It is characterized in that it is arranged and held so as to satisfy the error within.

[0051]

(Equation 2) (In the above formula (1), R: work holding plate diameter (mm), r: wafer diameter (mm), x: distance between wafers (mm), y: wafer and work holding plate outer peripheral end distance (mm), N : Number of wafers / work holding plate, π: circumference ratio, where the inter-wafer distance x is the closest distance between adjacent wafer outer peripheral portions.)

When a plurality of wafers are held on one work holding board, the arrangement of the wafers on the holding surface is extremely important. That is, the held wafers are polished under the same conditions as possible microscopically, that is, the polishing conditions and polishing rates are as uniform as possible between each wafer and within the polished surface of one wafer. It is important to achieve, the temperature of the surface to be polished,
The pressing force to the polishing cloth, the method of supplying the polishing agent solution, and the relative movement distance between the polishing cloth and the like are important factors. I got it.

When the above equation (1) is applied to a wafer of 200 mm or more, that is, when r is 200 mm or more, it is necessary to satisfy 5N ≦ 7, 5x ≦ 20, 7 ≦ y ≦ 22.

The diameter (r) of the wafer is increased to 300 mm
As a matter of course, the diameter (R) of the work holding plate becomes large for the above-mentioned wafer. Accordingly, it is necessary to increase the thickness (d) of the work holding plate in accordance with the diameter (R) in order to suppress mechanical deformation, thermal deformation due to temperature change, and the like to a predetermined value or less. As a result of the examination, the deformation amount in the normal direction of the holding surface of the work holding plate during the polishing operation, which is the basic principle of the present invention, is 100 μm or less, preferably 30 μm or less.
μm or less, the thickness d of the work holding
<D <bR (a = 0.04 to 0.08, b = 0.10 to 0.0.
12) is preferable.

A fifth aspect of the polishing method of the present invention is characterized in that a silicon wafer is polished using the above-described polishing apparatus of the present invention.

The polishing method according to the third aspect is preferably performed in an environment where the temperature change is within ± 2 ° C. That is, in order to realize such high-precision polishing, the fluctuation of the ambient temperature around the operation of the polishing apparatus is within ± 2 of a predetermined temperature.
It is preferable that the temperature be within ° C.

The manner of holding the work (wafer) on the work holding plate and the accuracy of the holding state, that is, the uniformity of the flatness of the work holding surface and the uniformity of the gap between the holding surface and the bonded surface of the wafer are important. It is. In particular, when bonding and holding the wafer to the work holding plate using an adhesive, the residual air bubbles in the adhesive layer between the wafer and the work holding plate, the bending of the wafer during bonding, the thickness of the adhesive layer Its uniformity is a problem.

Therefore, the method of bonding a work according to the present invention uses a work holding plate in which a plurality of fine holes for sucking and holding the work are opened in the bonding area, and uses the work holding plate from the rear side through the fine holes. The wafer is bonded to the work holding plate with an adhesive while exhausting air. With such a configuration, it is possible to eliminate the above-mentioned disadvantages of the conventional method, to reduce the thickness of the adhesive layer between the wafer and the work holding plate, and to improve the uniformity of the thickness.

At this time, in order to easily carry out the bonding, it is preferable to carry out the bonding at a normal temperature (20 ° C. to 30 ° C.), to carry out the bonding effectively and to reduce the thickness of the adhesive layer after bonding. In order to improve the uniformity (the thickness deviation is preferably within 0.015 μm for high-precision wafer processing) and minimize the residual air in the adhesive layer, it is necessary to perform the process from the time of coating to the stage before bonding. The viscosity of the adhesive is 1 mPa · s to 1
It is preferable to adjust between 0 mPa · s.

In order to effectively remove the heat generated by polishing by the temperature adjusting fluid of the work holding plate via the wafer, it is necessary to minimize the thermal resistance by the adhesive layer interposed between the wafer and the work holding plate. In addition, the average value of the thickness of the adhesive layer is 0.5 μm or less, preferably 0.5 μm, in order to suppress the fluctuation of the adhesive layer thickness due to the elastic deformation of the adhesive.
It is preferably 3 μm or less, and the deviation of the thickness is set to 0.3.
It is desirable that the thickness be 015 μm or less.

In the work holding plate of the present invention, a plurality of suction holes for vacuum-sucking the work are provided in the bonding region of the work bonding surface of the work holding plate so as to penetrate from the work bonding surface to the back surface of the work holding plate. It is characterized by.

By using the work holding plate of the present invention described above, the above-described method of bonding the work of the present invention can be effectively performed.

It is preferable to provide a concave portion or a rib structure on the back surface of the work holding plate.

By bonding and holding a silicon wafer on a work holding plate by the work bonding method of the present invention described above, a highly accurate wafer polishing process can be performed. At this time, when the above-described polishing apparatus of the present invention is used, the amount of deformation in the direction normal to the surface of the surface plate of the polishing surface plate during the polishing operation, which is the basic principle of the present invention, and / or the work holding surface of the work holding surface. It is extremely effective in suppressing the amount of deformation in the normal direction to 100 μm or less, preferably 30 μm or less, and realizing high precision polishing.

[0065]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. 1 to 9 in the accompanying drawings, but various modifications other than the illustrated examples may be made without departing from the technical idea of the present invention. Needless to say, this is possible.

FIG. 1 is a partially omitted sectional explanatory view showing an example of the polishing apparatus of the present invention. FIG. 2 is a sectional explanatory view of one example of a polishing platen used in the polishing apparatus of the present invention. FIG. 3 is a sectional explanatory view of one example of a work holding plate used in the polishing apparatus of the present invention. FIG. 4 is an explanatory diagram showing an example of the work bonding method of the present invention.

In FIG. 1, reference numeral 28 denotes a polishing apparatus according to the present invention.
And a polishing platen 29. The polishing platen 29 includes:
As shown in FIG.
A large number of recesses 34 are provided on the back of the polishing table 29.
Have been killed. The recess 34 is formed by the seal member 30
The surface side is sealed and a temperature adjusting fluid such as cooling water H ₁
Is constituted. The cooling water H₁The flow path of the surface plate described later
Cooling water heat exchanger K_TwoConnected to the cooling water H₁Is the heat exchanger
K_TwoHeat exchange is possible at the time of polishing.
The heat generated in the board 29 is absorbed. Polishing of the polishing platen 29
A polishing cloth 31 is adhered to the polished surface.

Reference numeral 32 denotes a rotating shaft provided at the center of the back of the polishing table 29, and reference numeral 35 denotes a center roller provided at the center of the surface of the polishing table 29. The center the longitudinal direction of the said rotary shaft 32 long hole 33 is bored, the long hole 33 constitutes the temperature adjusting fluid, for example, a portion of the flow path of the cooling water H _2, of the cooling water H ₂ flow path is connected to the platen rotary shaft cooling water heat exchanger K ₄ to be described later, the platen rotary shaft 3 during polishing device driver
The heat generated by the mechanical friction accompanying the rotation of 2 is absorbed.
Reference numeral 7 denotes a frame that supports the back surface of the polishing platen 29 via a support plate 43 and a bearing member 44.

Reference numeral 14 denotes a polishing agent supply pipe which polish a polishing agent 41 adjusted to a predetermined flow rate and temperature by a polishing agent supply device (not shown) to a center roller 35 (a guide roller is not shown). The abrasive 41 is supplied onto the polishing pad 31 through the agent introduction hole 42.

Reference numeral 36 denotes a top block, on the lower surface of which a work holding plate 38 is attached via an elastic body 37 such as rubber. A work is provided on the bonding surface of the work holding plate 38.
For example, the wafer W is bonded by an adhesive 39. Numeral 40 is a rotating shaft erected on the top block 36.

[0071] 47 is a long hole provided at the center portion of the rotary shaft 40, it constitutes the long hole 47 a temperature regulating fluid, for example, a portion of the flow path of the cooling water H _4, the rotary shaft 40
And is provided for each work holding plate. The flow path of the cooling water H ₄ is connected to a work holding plate rotary shaft cooling water heat exchanger K ₅ to be described later, performs endothermic heat generated in the rotation shaft 40 when the work holding plate rotation.

As shown in FIG. 3, a large number of recesses 50 are formed in the back surface of the work holding plate 38. 45
Is a suction hole for vacuum suction, which penetrates from the bottom of the concave portion 50 located inside the wafer bonding region 46 to the back surface of the work holding plate 38. As will be described later, the suction hole 45 is formed in the wafer bonding area 4 of the work holding plate 38.
When bonding the wafer W by the adhesive 39 to 6, but is used to perform bonding by vacuum suction, the recess 50 when polishing the wafer W is temperature adjusting fluid, for example cooling water H ₃ A part of the flow path. The flow path of the cooling water H ₃ is connected to a work holding plate cooling water heat exchanger K ₃ to be described later, the cooling water H ₃ is capable heat exchange in the heat exchanger K _3, generated on the work holding plate 38 It is provided for each work holding board individually.

Next, a method of bonding the wafer W to the work holding plate 38 will be described with reference to FIG.
In FIG. 4, reference numeral 48 denotes an adhesive base,
Is used when the wafer W is bonded to the wafer bonding area 46 with the adhesive 39. A flat-bottom recess 51 is formed in a portion of the upper surface of the bonding base 48 corresponding to the wafer bonding region 46. A through hole 49 penetrates from the bottom of the concave portion 51 to the lower surface of the adhesive base 48.

The through hole 49 is connected to an exhaust system such as a vacuum pump to connect the through hole 49, the recess 51, and the work holding plate 38.
The concave portion 50 and the suction hole 45 of the wafer W
Can be sucked into the wafer bonding area 46 of the work holding plate 38. At this time, the adhesive 39 is interposed between the wafer W and the wafer bonding area 46. However, the wafer W is uniformly pressed by the atmospheric pressure by the vacuum suction of the bonding surface of the wafer W. Therefore, the uniformity of the film thickness of the adhesive 39 is extremely good, and since the air is sucked downward, the bonding can be performed with little air remaining in the adhesive layer.

As an adhesive used for bonding the work W to the work holding plate 38, the bonding ability can be exhibited between 20 ° C. and 30 ° C., and the viscosity at the time of bonding is 1 mPa.
· An adhesive having a pressure of 10 mPa · s to 10 mPa · s is preferably used. In addition, the average value of the thickness of the adhesive at the work bonding portion is 0.1 μm.
m to 0.5 μm, the deviation of the thickness is 0.015 μm.
It is preferable to adhere uniformly so as to be within m. As a preferable adhesive, a polyol-based polyurethane adhesive is exemplified, and one obtained by dissolving this adhesive in an alcohol solvent such as methanol or ethanol, or an aqueous emulsion is suitable. Further, an isocyanate compound may be added as a curing agent.

As shown in FIG. 1, the wafer W bonded to the work holding plate 38 with almost no residual air in the adhesive layer and having a very high thickness is bonded to the top block 36 as shown in FIG. Then, the wafer W is polished by pressing it against the surface of the polishing pad 31 of the polishing platen 29.

At the time of polishing, the heat generated by the polishing table 29 is absorbed by the cooling water H ₁ , the heat generated by the rotating shaft 32 is absorbed by the cooling water H ₂ , and the heat generated by the work holding plate 38 is absorbed by the cooling water H ₃ . The heat generated by the rotating shaft 40 is absorbed by the cooling water H ₄ .

As described above, the cooling waters H _{1 to} H ₄ are respectively provided to the respective polishing members and the rotating mechanism constituting the polishing apparatus 28 of the present invention.
So that the amount of deformation in the normal direction of the upper surface of the polishing platen 29 during the polishing operation is 100 μm.
m, preferably 30 μm or less, more ideally 1 μm or less.
The deformation amount of the work holding surface of the work holding plate 38 in the normal direction can be suppressed to 100 μm or less, preferably 30 μm or less, and more ideally 10 μm or less.

The material of the polishing platen preferably has a coefficient of thermal expansion of 5 × 10 ⁻⁶ / ° C. or less. As such a material, a so-called stainless steel of Fe—Co—Ni—Cr type is used. Invar can be given.

The polishing apparatus 28 of the present invention controls the flow rate and / or the temperature of the temperature adjusting fluid so that the temperature change of the polishing platen 29 and / or the temperature change of the work holding plate 38 during the polishing operation can be controlled within a predetermined range. It is one of the characteristic constitutions to control within. The characteristic configuration is can be achieved by controlling the flow rate and temperature of the cooling water H ₁ to H ₄ described above. That is, by suppressing the flow rate and the temperature of each of the cooling waters H _{1 to} H ₄ described above, the temperature change of the polishing platen 29 and / or the temperature change of the work holding surface of the work holding plate 38 during the polishing operation can be controlled within a predetermined range.
For example, it can be controlled preferably within 3 ° C., more preferably within 2 ° C., respectively.

The polishing platen 29 shown in FIGS. 1 and 2 is schematically illustrated to explain the concept of the present invention, and a more specific preferred structure of the polishing platen 29 is shown in FIGS. A description will be given based on FIG. FIG. 5 is a partially cutaway top view showing the planar structure of the flow path of the internal temperature adjusting fluid in another example of the polishing platen. FIG. 6 shows the upper channel portion and the lower channel portion of the polishing platen of FIG.
It is a longitudinal cross-sectional view in the -A line and the OB line direction. FIG. 7 shows FIG.
It is a rear view of the polishing surface plate of FIG.

Surface 2 of polishing table 29 shown in FIGS.
Reference numeral 9a denotes a flat surface, and a polishing cloth 31 is stuck thereon during use as shown in FIG. As shown in FIGS. 6 and 7, a large number of annular or radial ribs 8 are provided on the back surface 29b of the polishing platen 29. Thus, a large number of ribs 8
By forming the back side on the back surface, the strength can be maintained and the weight can be reduced.

Channels 9a and 9b for a temperature adjusting fluid, for example, cooling water, are provided inside the polishing platen 29. Of these, the upper channel 9a has a meandering structure to improve the heat exchange efficiency. It is devised so that it is performed.

The upper flow path 9a communicates with the lower flow path 9b at the peripheral portion of the polishing platen. When the temperature adjusting fluid flows through the flow path 9, the upper flow path 9a starts from the center of the upper flow path 9a. From the peripheral portion of the lower flow passage 9b to the central portion through the portion, and conversely, from the central portion of the lower flow passage 9b through the peripheral portion to the central portion from the peripheral portion of the upper flow passage 9a. it can.

Next, an example of total calorie control, which is one of the features of the polishing apparatus and the polishing method of the present invention, will be described with reference to FIGS. FIG. 8 is a block diagram showing a total calorific value control system according to the present invention. FIG. 9 is a flowchart of the total calorific value control in the present invention.

8 and 9, Q is a total calorie control CPU, a slurry calorie control CPU (Q ₁ ), a platen calorie control CPU (Q ₂ ), and a work holding plate calorie control CPU.
(Q ₃ ), a converter T ₁ for converting temperature signals from the temperature sensors S ₂ and S ₃ embedded in the upper and lower portions of the surface plate into electric signals, and a temperature sensor embedded in the upper and lower portions of the work holding plate. being connected to the thermal imaging device U to display the transducer T ₂ and the polishing pad surface temperature and converts into an electric signal the temperature signal from S ₄ and S _5, the slurry various commands in response to signals from the devices Calorie control CPU (Q ₁ ), surface plate calorie control CPU
(Q ₂ ) and the work holding board heat quantity control CPU (Q ₃ ). Note that the converters T ₁ and T ₂ employ a configuration having an action of converting signals from temperature sensors S ₂ , S ₃ and temperature information such as infrared rays and ultrasonic waves from S ₄ , S ₅ into electric signals. It is preferred to do so.

The slurry calorie control CPU (Q ₁ ) is connected to the slurry flow sensor I ₁ , slurry outlet temperature sensor S ₆ , slurry inlet temperature sensor S ₁ , slurry flow controller V ₁ , and slurry heat exchanger K _1. and which, put each necessary instructions to the slurry flow controller V ₁ and the slurry heat exchanger K ₁ on the basis of information from the slurry flow sensor I _1, a slurry outlet temperature sensor S ₆ and the slurry inlet temperature sensor S _1.

The platen heat quantity control CPU (Q ₂ ) includes a platen cooling water flow sensor I ₂ , a platen outlet temperature sensor S ₈ , a platen inlet temperature sensor S ₇ , a platen cooling water flow controller V _2, It is connected to the platen cooling water heat exchanger K _2, plate cooling water flow rate sensor I _2, based on information from the platen outlet temperature sensor S ₈ and platen inlet temperature sensor S _7, platen cooling water emit respective instructions necessary to flow regulator V ₂ and the surface plate cooling water heat exchanger K _2.

The work holding board heat quantity control CPU (Q ₃ ) is provided for each work holding board, and the work holding board cooling water flow rate sensor I ₃ , the work holding board outlet temperature sensor S ₁₀ , the work holding board inlet temperature The sensor S _{9 is connected to} the work holding board cooling water heat exchanger K ₃ and the work holding board cooling water flow controller V ₃ , and the work holding board cooling water flow sensor I ₃ , the work holding board outlet temperature sensor S _10, issue each necessary instructions to work holding plate cooling water heat exchanger K ₃ and a work holding plate cooling water flow rate adjuster V ₃ based on information from a work holding plate inlet temperature sensor S _9.

At the same time, the platen rotary axis heat quantity control CPU (Q ₄ ) and the individual work holding plate rotary axis heat quantity control CPUs (Q ₅ ) are connected to the total heat quantity control CPU (Q), and the polishing action is performed. The amount of heat generated due to the mechanical action associated with the operation of the polishing apparatus other than the heat generated by the polishing apparatus is removed, and the temperature of the polishing apparatus is controlled to a predetermined temperature by suppressing the temperature change.

As described above, it is preferable to individually suppress the temperature fluctuation of each component of the polishing apparatus due to various amounts of heat generated at the time of the polishing operation for each element. Can be controlled integrally with the platen calorific value control system, or the work holding plate rotation axis calorific value control system and the work holding plate calorie control system can be integrally controlled for each individual work holding plate.

Further, as shown in the figure, the temperature adjusting fluid of the platen rotary shaft calorie control system or the work holding plate rotary shaft calorie control system is executed by an external cooling method using a gas instead of a liquid such as water as shown in the figure. Is also possible.

In this case, it is important that the temperature of the surface plate and the work holding plate is not affected as much as possible by the heat generated by the mechanical operation of the apparatus other than the heat generated by the direct polishing action. is there. Therefore, the platen rotary shaft calorie control CPU and the work holding plate rotary shaft calorie control C
PUs are not connected to the total calorie control CPU.
Various modifications can be made to the temperature control of each component as long as the realization of the basic philosophy of the present invention is not hindered, such as independently performing the calorie control (temperature control) of each system by U.

[0094]

EXAMPLES The contents of the present invention will be described in more detail with reference to examples. However, the contents of the present invention are not limited to these examples. It is applied as.

(Example 1) A batch type polishing apparatus having the same basic structure as the polishing apparatus shown in FIG. 1 and having a polishing platen and a four-axis work holding plate rotating mechanism was constructed as follows. 1. Polishing surface plate: Invar material (Shinpo Kokuetsu Steel Co., Ltd. SLE-
20A (Fe-Co-Ni-Cr system) was used to form an integral structure by casting, and the cooling water flow path shown in FIGS. 5 and 6 was formed. Further, as shown in FIG. 5, a part of the upper surface of the surface plate is cut away to show a part of the flow path 9 of the temperature adjusting fluid, the flow path 9 is formed to meander, and the fluid in the flow path 9 It is designed so that turbulence is likely to occur, the average flow velocity is increased, the heat transfer coefficient is increased as much as possible, and the portion that does not form the flow path 9 acts as the internal rib structure 8a to maintain the platen strength. 2. Work holding board: Using alumina ceramics (manufactured by Kyocera Co., Ltd.), a cooling water flow path is formed on the back surface corresponding to the wafer bonding portion as shown in FIG. There were provided a total of 85 (17 per wafer) pores for exhaust (diameter: 0.3 ± 0.1 mmφ) penetrating through. 3. Polishing cloth: Suba600 manufactured by Rodale was stuck on the upper surface of the polishing platen.

4. 4. Other polishing equipment performance: a) Platen rotation unevenness: ± 0.5% b) Surface plate upper surface rotation deviation: 15 μm c) Surface plate rotation axis deviation: 30 μm Configuration of Temperature Control System As with the total calorie control system shown in FIGS. 8 and 9,
Fluid flow system for temperature control of polishing platen, fluid flow system for temperature control of work holding plate, abrasive solution circulation system, fluid flow system for temperature control of rotating shaft of polishing platen and work holding for each work holding plate The fluid flow rate and the temperature of each of the fluid path systems for adjusting the temperature of the rotating shaft of the board are adjusted. 6. Outline of polishing operation 5 200mmφ silicon wafers (750μm thick)
The four wafers having a diameter of 565 mm are satisfactorily satisfying the following formula, and the viscosity at 25 ° C. is 5 mPa so that the center of the wafer is evenly distributed on a circle having a radius of 175 mm from the center.
Adhesion was performed at room temperature (25 ° C.) using an adhesive adjusted to s (a methanol solution of a polyol-based polyurethane adhesive). The application of the adhesive was performed using a spin coating apparatus, and the bonding of the wafer to the work holding board was performed using the apparatus shown in FIG.

[0097]

(Equation 3) (In the above formula (1), R: work holding plate diameter (mm), r: wafer diameter (mm), x: distance between wafers (mm), y: wafer and work holding plate outer peripheral end distance (mm), N : Number of wafers / Work holding plate, π: Pi

At this time, bonding is performed while evacuating from the back surface of the work holding plate using a vacuum exhaust device separately prepared for each bonding portion of each wafer and a jig for suctioning the back surface of the work holding plate until the bonding is completed (0. (5 minutes) The evacuation was continued to 200 mmTorr or less. By bonding while exhausting in this manner, the thickness of the adhesive layer at the bonding site is between 0.20 to 0.22 μm on average for each wafer, and the deviation of the thickness within each wafer is 0.2. It was within 012 μm. The thickness of the adhesive layer was measured using an automatic film thickness mapping system F50, which is a thin film measurement device manufactured by Filmmetrics. The thickness measurement of the adhesive layer was performed after the adhesive was applied by spin coating, but after the application, the viscosity of the adhesive increases due to the evaporation of the solvent. However, it has been confirmed that the adhesive is not sucked into the exhaust holes, and the thickness of the adhesive layer after bonding is substantially equal to the thickness of the adhesive layer after applying the adhesive. It can be said that there is no change.

A total of 20 wafers thus bonded to the work holding plate were polished under the following conditions.

(1) Polishing platen Rotation speed: 30 rpm ± 0.5% Cooling water: variable at 50 l / min or less Inlet temperature: room temperature -1 ° C (within ± 0.5 ° C) Outlet temperature: room temperature + 1 ° C or less

(2) Work holding board (free rotation) Additional load: 250 g per cm ^{2 of} wafer surface Cooling water: (per unit) Variable at 20 l / min or less Inlet temperature: Room temperature -1 ° C (± 0.5 ° C) Outlet temperature: Room temperature + 1 ° C or less

(3) Abrasive solution SiO ₂ content: 20 g / l, pH 10.5 to 10.8, specific gravity 1.02 to 1.03 Supply amount: 30 l / min (4) Polishing time: 10 min (5 ) Polishing amount: 10 μm (6) Room temperature: 25 ± 1 ° C.

During this time, the temperature of each cooling water system was controlled by the total calorific value control system shown in FIGS.
In particular, the temperature of the exposed surface of the polishing cloth is measured using a thermal image sensor over a range corresponding to the diameter of the work holding plate on the radius of the polishing platen, and the average value is the ambient temperature (room temperature).
The supply temperature (slurry inlet temperature) of the abrasive solution was controlled so as to be within 3 ° C. The progress is shown in FIG.

As described above, the temperature of the polishing cloth surface during the polishing operation was controlled within 3 ° C. of room temperature (25 ° C.). FIG. 11 shows an analysis of the temperature distribution from the rear surface of the work holding plate to the lower surface of the polishing platen in this case.
Polishing table temperature is the temperature before polishing operation (environmental temperature = room temperature)
At 25 ° C., the temperature change is suppressed within 3 ° C. Further, as shown in FIG. 23B, it can be seen that the displacement amount in the normal direction of the upper surface of the platen at this time is suppressed to 10 μm or less at any position with respect to before polishing.

After polishing the wafer polished under the above conditions, each wafer was peeled off from the work holding plate, and then washed with pure water → alkali → NH ₄ OH / H ₂ O ₂ → pure water.
Finishing accuracy was measured. Table 1 shows the results.
The results are shown in comparison with the results.

[0106]

[Table 1]

The abbreviations in Table 1 are as follows. GBIR: Global Back-side Ideal Range (= TTV) (difference between the maximum and minimum thicknesses over the entire area from the back surface of the wafer as a reference plane) SBIR: Site Back-side Ideal Range (= LTV) [ Difference between the maximum value and the minimum value in a certain area (site) using the back surface of the wafer as a reference plane] SFQR: Site Front least sQuares <site> Range
(Weight difference of wafer surface for each site)

The measurement conditions in Table 1 are as follows. Measuring machine: ADE9600E + (made by ADE Corporation) Wafer: 8-inch wafer Number of sheets: 20 (1 batch) Measurement area: Excluding 2 mm from the periphery SFQRmax, SBIRm
The measurement area is divided into 25mm x 25mm for both ax.

(Comparative Example 1) As Comparative Example 1, an example of polishing by a conventional technique and a result thereof will be described in comparison with Example 1.

The basic configuration of the polishing apparatus is as follows. 1. Polishing surface plate: upper surface plate 1 as shown in FIGS.
2 (a flat plate made of SUS410) and a lower platen 23 made of cast iron (FC-30) having a recess 21 serving as a cooling water channel formed on the upper surface thereof, and the platen 10 was formed by fastening with a fastener 11.

[0111] 2. Work holding plate: As shown in FIG. 18, a work holding plate 13 made of alumina ceramics is provided with an upper load 1 having a rotating shaft 18 via a rubber elastic body 13a.
5 was pressed downward. 3. Polishing cloth: Polishing plate 1 made of SuBa600 manufactured by Rodale
0.

4. Other polishing equipment performance a) Platen rotation unevenness: ± 2% b) Platen upper surface rotation fluctuation: 30 μm c) Platen rotation axis fluctuation: 140 μm

[0113] 5. Figure 1 shows the total calorie control system.
4 and FIG. 14 and 15 are the same as those shown in FIGS. 8 and 9 except that the temperature adjusting fluid supply system of the work holding plate, the polishing platen rotating shaft temperature adjusting fluid system, and the work holding plate rotating shaft temperature adjusting fluid system do not exist. Since the configuration is the same as that of FIG. 9, the description will not be repeated.

6. Outline of polishing operation A total of 20 wafers (200 mmφ,
Five pieces each having a thickness of 750 μm were adhered and held equally on four work holding boards having a diameter of 565 mm on a circumference having a radius of ／ (175 mm) from the center so that the center of the wafer almost coincided. .

[0115] Adhesion was previously performed on the surface (back surface) of the wafer to be adhered, beeswax-based adhesive Sky Liquid HM-401 manufactured by Nikka Seiko.
After dissolving No. 1 in isopropyl alcohol and applying the solution by a spin coating apparatus, the wafer is heated to 50 ° C. and held for about 0.5 minute to volatilize and remove the solvent. Thereafter, the wafer is heated to about 90 ° C. to melt the wax (viscosity at 90 ° C .: 1000 mPa · s), and then placed at a predetermined position on the work holding surface of the work holding board also heated to 90 ° C. The surface to be polished (surface) shown in FIG. 21 is pressed against a bonding jig having a rubber elastic body formed in a convex shape to push air out of the adhesive layer at the bonding site, and then release the bonding jig. Then, the wafer was cooled to room temperature by self-cooling.

In the case of bonding by this method, since the work holding plate and the wafer are bonded while being heated to 90 ° C., the deformation due to the difference in the coefficient of thermal expansion between the wafer and the work holding plate and the wax, and the pressing by the rubber elastic body. The average thickness of the adhesive layer for each wafer was 0.3 to 0.8 .mu.m, and the deviation for one wafer was about 0.1 .mu.m due to uneven application of force at the time.

7. Polishing conditions (1) Polishing platen Rotation speed: 30 rpm ± 2% Cooling water: 15 l / min Inlet temperature: 12 ° C. ± 1 ° C. Outlet temperature: Market

(2) Work holding board (free rotation) Applied load: 250 g per cm ^{2 of} wafer surface (3) Abrasive solution AJ-1325, pH 10.5 to 10.8, SiO ₂ : 20
g / l, specific gravity: 1.02 to 1.03 [brand name of colloidal silica abrasive manufactured by Nissan Chemical Industries, Ltd.] Supply amount: 10 l / min Supply-side outlet temperature: 23 ° C. ± 1 ° C.

(4) Polishing time: 10 min (5) Polishing amount: 10 μm

FIG. 14 and FIG. 1 show the temperature control of the cooling water system.
FIG. 12 shows the progress during the polishing operation, which was controlled by the total calorific value control system shown in FIG. The temperature of the surface of the polishing pad was measured by a thermal image sensor in the same manner as in the embodiment. In this case, however, the surface temperature of the polishing pad was performed without any particular control. The change in the polishing cloth surface temperature at this time is also shown in FIG. 13, and the temperature change increased from about 20 ° C. before the start of polishing to about 32 ° C. at the end of polishing. The temperature distribution from the work holding plate to the polishing platen in this case is analyzed as shown in FIG. 13, and a temperature change of 10 ° C. or more occurs with respect to the temperature distribution of the polishing platen and the work holding plate before polishing. The amount of thermal deformation of the polishing platen in the normal direction reaches 100 μm or more depending on the location as shown in FIG.

The polishing finish accuracy of the obtained wafer is shown in Table 1.
As shown in the above, the result was lower than that of the example.

[0122]

As described above, according to the polishing apparatus and the polishing method of the present invention, it is possible to carry out high-precision mirror processing of a workpiece, for example, a wafer having a diameter of 8 inches to 12 inches or more with high efficiency. Becomes Further, according to the method for bonding a work of the present invention, a work, for example, a wafer, can be uniformly bonded to a work holding plate without causing bending, thereby achieving an effect of contributing to high-precision mirror processing of the wafer. can do.

[Brief description of the drawings]

FIG. 1 is a partially omitted cross-sectional explanatory view showing one example of a polishing apparatus of the present invention.

FIG. 2 shows a polishing table 1 used in the polishing apparatus of the present invention.
It is sectional explanatory drawing which shows an example.

FIG. 3 is a sectional explanatory view showing an example of a work holding plate used in the polishing apparatus of the present invention.

FIG. 4 is an explanatory view showing one example of a work bonding method of the present invention.

FIG. 5 is a partially cutaway top view showing a planar shape of a fluid channel for temperature adjustment in another example of the polishing platen of the present invention.

FIG. 6 is a longitudinal sectional view showing an upper channel portion and a lower channel portion of the polishing platen of FIG.

FIG. 7 is a rear view of the polishing platen shown in FIG. 5;

FIG. 8 is a block diagram showing an arrangement of each device in the integrated heat quantity control system according to the present invention.

FIG. 9 is a flowchart showing a control operation of the total heat quantity control system in the present invention.

FIG. 10 is a graph showing a relationship among a polishing time, a polishing cloth surface temperature, an abrasive solution supply temperature, and an abrasive solution return temperature in Example 1.

FIG. 11 is an analysis diagram of a temperature distribution from the back surface of the work holding plate to the lower surface of the polishing platen in the first embodiment.

FIG. 12 is a graph showing the relationship among the polishing time, the polishing cloth surface temperature, the abrasive solution supply temperature, the abrasive solution return temperature, the polishing platen cooling water supply temperature, and the polishing platen cooling water return temperature in Comparative Example 1. is there.

FIG. 13 is an analysis diagram of a temperature distribution from the back surface of the work holding plate to the lower surface of the polishing platen in Comparative Example 1.

FIG. 14 is a block diagram showing an arrangement of each device in the total heat quantity control system used in Comparative Example 1.

FIG. 15 is a flowchart showing a control operation of the total calorific value control system used in Comparative Example 1.

FIG. 16 is a top view of the polishing platen used in Comparative Example 1.

17 is a longitudinal sectional view of FIG.

FIG. 18 is a longitudinal sectional view of a work holding board used in Comparative Example 1.

FIG. 19 is an explanatory side view showing an example of a conventional wafer polishing apparatus.

FIG. 20 is an explanatory sectional view showing an example of a conventional polishing platen.

FIGS. 21A and 21B are schematic explanatory views showing one example of a conventional method of bonding a wafer to a work holding board, wherein FIG.
Is a drawing showing a pressure bonding state.

FIG. 22 is a schematic explanatory view showing another conventional example of a method of bonding a wafer to a work holding board.

FIG. 23 is a graph showing the amount of displacement in the normal direction before and during polishing of the polishing platen in Example 1 and Comparative Example 1,
(A) shows the measurement position, (b) shows the displacement in Example 1, and (c) shows the displacement in Comparative Example 1, respectively.

[Explanation of symbols]

1: vacuum vessel, 2: bellows, 3: bellows lifting / lowering cylinder, 4: bellows internal pressure adjustment pipe, 5: vacuum vessel internal pressure adjustment pipe, 6: vacuum suction pipe, 7: frame,
8: rib, 8a: internal rib structure, 9, 9a, 9b: fluid path for temperature adjustment, 10: conventional polishing platen, 11: fastener, 12: upper platen, 13, 20: conventional work holding Board,
13a: rubber elastic body, 14: abrasive supply pipe, 1
5: upper load, 16, 31: polishing cloth, 17: rotating shaft, 1
8: rotating shaft, 19: abrasive solution, 20a: adhesive surface, 21, 34, 50, 51, 52: concave portion, 22: adhesive, 23: lower surface plate, 24: wafer pressing member, 25:
Pressurizing head, 26: Pressurizing cylinder, 27: Air bag, 28: Polishing device of the present invention, 29: Polishing platen of the present invention, 29a: Polishing platen surface, 29b: Polishing platen back surface, 3
0: seal member, 32: rotating shaft, 33: long hole, 35: center roller, 36: top block, 37: elastic body,
38: Work holding plate of the present invention, 39: adhesive, 40: rotating shaft, 41: abrasive, 42: abrasive introduction hole, 4
3: support plate, 44: bearing member, 45: suction hole, 46: wafer bonding region, 47: long hole, 48: adhesive base, 49: _{through-hole, H, H 1, H 2} , H 3, H 4: Cooling water, W: work (wafer).

Continued on the front page (51) Int.Cl. ⁷ Identification FI FI Theme Court II (Reference) B24B 37/04 B24B 37/04 A J (72) Inventor Toshiyuki Hayashi 2174-1, Gundam-cho, Gunma-gun, Gunma-gun, Gunma Prefecture Semiconductor industry Co., Ltd. Kamigo factory F term (reference) 3C058 AA07 AA14 AB04 AB08 AC01 AC04 BA08 CB01 DA17

Claims (31)

[Claims] 1. A polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held by the work holding plate while flowing an abrasive solution, wherein the surface of the surface plate of the polishing surface plate during a polishing operation. A polishing apparatus characterized in that the amount of deformation in the normal direction and / or the amount of deformation in the normal direction of the work holding surface of the work holding board is suppressed to 100 μm or less. 2. A polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held on the work holding plate while flowing an abrasive solution, wherein the polishing surface plate is integrally formed by casting. The structure of the polishing platen has a plurality of concave portions and / or ribs on the back surface, and a portion for forming a temperature control fluid channel inside the platen and not forming the channel acts as an internal rib structure. A polishing apparatus characterized in that the polishing is performed. 3. The polishing platen according to claim 1, wherein the material constituting said polishing platen has a coefficient of thermal expansion of 5 × 10 ⁻⁶ / ° C. or less, and its corrosion resistance is substantially equal to that of stainless steel. Or the polishing apparatus according to 2. 4. The polishing apparatus according to claim 3, wherein the material of said polishing platen is Invar. 5. A polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held on the work holding plate while flowing an abrasive solution, wherein the flow rate and / or the temperature of the temperature adjusting fluid is controlled. A polishing apparatus characterized by controlling a temperature change of a polishing surface plate and / or a temperature change of a work holding plate during a polishing operation within a predetermined range. 6. The polishing apparatus according to claim 5, wherein a temperature change in an arbitrary position of the polishing platen and / or the work holding plate during the polishing operation is within 3 ° C. 7. The method according to claim 1, wherein a temperature and / or a flow rate of the polishing agent solution is controlled to control a temperature fluctuation at an arbitrary position on a polishing surface of the polishing cloth during polishing operation to 10 ° C. or less. The polishing apparatus according to any one of claims 1 to 6. 8. The polishing apparatus according to claim 1, wherein rotation unevenness of said polishing platen is suppressed to 1% or less. 9. The polishing apparatus according to claim 1, wherein the surface fluctuation during rotation of the polishing surface of the polishing platen is suppressed to 15 μm or less.
The polishing apparatus according to any one of claims 8 to 13. 10. The rotation deviation of the rotation axis of the polishing platen is 3
The polishing apparatus according to any one of claims 1 to 9, wherein the polishing apparatus is suppressed to 0 µm or less. 11. The polishing apparatus according to claim 1, wherein the work holding plate has a concave portion on the back surface or has a rib structure. 12. The work holding plate is made of alumina ceramics or SiC.
2. The polishing apparatus according to 1. 13. The polishing apparatus according to claim 12, wherein a plurality of fine holes for sucking and holding the work are opened in a region where the work holding plate is bonded to the work. 14. A polishing apparatus which has a polishing surface plate and a work holding plate and polishes a work held on the work holding plate while flowing an abrasive solution. A polishing method characterized in that a deformation amount in a normal direction and / or a deformation amount in a normal direction of a work holding surface of a work holding board is suppressed to 100 μm or less. 15. A polishing method comprising a polishing platen and a work holding plate, wherein the work held by the work holding plate is polished while flowing an abrasive solution, using a polishing cloth stuck on the polishing platen. When polishing the surface to be polished of the work, a fluctuation in temperature at an arbitrary position on the polishing surface of the polishing cloth during the polishing operation is set to 10 ° C. or less. 16. A polishing method comprising a polishing surface plate and a work holding plate, wherein the work held on the work holding plate is polished while flowing an abrasive solution, wherein the fluctuation of the temperature of the work during polishing is 10 ° C. or less. A polishing method characterized in that the polishing is suppressed to a minimum. 17. A method for controlling a temperature and / or a flow rate of the polishing agent solution to reduce fluctuations in temperature and / or wafer temperature at an arbitrary position on a polishing surface of a polishing cloth during a polishing operation.
16. The method according to claim 15, wherein the temperature is controlled to 0 ° C. or less.
6. The polishing method according to 6. 18. A polishing method using a polishing apparatus having a polishing surface plate and a work holding plate for polishing a work held on the work holding plate, wherein a plurality of wafers are placed on the work holding plate by the following formula (1). A polishing method characterized by arranging and maintaining the relationship of (1) and (2) within an error of 2 mm or less. (Equation 1) (In the above formula (1), R: work holding plate diameter (mm), r: wafer diameter (mm), x: distance between wafers (mm), y: wafer and work holding plate outer peripheral end distance (mm), N : Number of wafers / Work holding plate, π: Pi 19. When r is 200 mm or more and 5 ≦ N ≦ 7.5.
19. The polishing method according to claim 18, wherein ≤x≤20 and 7≤y≤22. 20. The thickness d of the work holding plate is aR <d <b
20. The polishing method according to claim 19, wherein R (a = 0.04 to 0.08, b = 0.10 to 0.12). 21. A polishing method according to claim 14, wherein the polishing apparatus is used to polish a silicon wafer. 22. The polishing method according to claim 21, wherein the polishing is performed in an environment where a temperature change is within ± 2 ° C. 23. A wafer holding plate having a plurality of holes for sucking and holding a work in a contact area, and bonding a wafer while exhausting air from the back side of the work holding plate through the holes. A method of bonding a work, wherein the work is bonded to a work holding plate with an agent. 24. The method according to claim 23, wherein the bonding is performed at a temperature between 20 ° C. and 30 ° C. 25. The method according to claim 24, wherein an adhesive having a viscosity of 1 mPa · s to 10 mPa · s at the bonding temperature is used. 26. The method according to claim 23, wherein the average value of the thickness of the adhesive at the work bonding portion is in the range of 0.1 μm to 0.5 μm, and the deviation of the thickness is within 0.015 μm. 26. The method according to any one of claims 25. 27. A work holding apparatus, wherein a plurality of suction holes for vacuum-sucking the work are provided in the bonding area of the work bonding surface of the work holding board so as to penetrate from the work bonding face to the back of the work holding board. Board. 28. The work holding plate according to claim 27, wherein a concave portion or a rib structure is provided on a back surface of the work holding plate. 29. A method according to claim 23, wherein the work holding plate according to claim 27 or 28 is used. 30. A polishing method, characterized in that a silicon wafer is adhered and held on a work holding board and polished by the method according to any one of claims 23 to 26 and 29. 31. A polishing method according to claim 30, wherein the polishing apparatus according to claim 1 is used.