JPH1148135A - Device and method for grinding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To equalize pressure applied to each of plural ground materials, by providing sliding members between a block which holds ground materials and pressure means, and by making it possible that the block slides in relation to the pressure means during the grinding of the ground materials. SOLUTION: The lower part of a pressure head 3 is provided with block pressure parts 37 which change a surface shape of a block freely in the radius direction as they apply pressure on the block 4, and the pressure is controlled according to the displacement of the block 4 detected by a micrometer 33. And, sliding members 40 having a low friction coefficient are inserted between the block pressure parts 37 and the block 4. Thus, the rotation of the block 4 is slightly deviated from that of the pressure head 3. That is, the block 4 relatively slides and rotates against the pressure head 3. Thus, the locally pressured position is gradually deviated on wafers 5, then a phenomenon that only a particular wafer 5 is always applied with pressure is done away with.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor wafer polishing apparatus and a polishing method suitable for a batch polishing type silicon wafer polishing machine, and more particularly to a semiconductor wafer capable of high flatness polishing. To a polishing apparatus and a polishing method.

[0002]

2. Description of the Related Art Conventionally, as a device for mirror-polishing the surface of a semiconductor wafer, a polishing device called a wafer polishing machine has been used. A general configuration of this polishing apparatus is a block that holds a wafer to be polished, a platen having a polishing pad attached to a surface of the block that is arranged opposite to the side that holds the wafer, and a plate that holds the block. A pressurizing mechanism for pressurizing the platen, and the wafer is mirror-polished by sliding the block and the platen while pressing in the direction of the platen by the pressurizing mechanism. .

[0003] One of the performances required of such a polishing apparatus is that the silicon wafer to be polished is polished with a uniform thickness and high flatness on the surface. This is to prevent uneven pressure from being applied to the platen in the plane of the wafer pressed against the platen.

Conventionally, as a polishing apparatus for satisfying such a demand, for example, Japanese Patent Application Laid-Open No. 63-144953 discloses a polishing apparatus in which a liquid is introduced between a block (mount plate) and a pressure mechanism (mount head). The elastic tube is provided in a spiral shape, and the block is pressed by the pressing mechanism through the elastic tube, so that the pressure applied between the wafer and the platen held on the lower surface of the block and each part of the lower surface of the wafer is reduced. Discloses a polishing apparatus designed to be uniform.

[0005]

However, even if the pressure on the entire block is made uniform as described above,
Note that a local difference in the pressing force may occur. In particular, the circumferential weight of the rotating block becomes uneven, and only one or several specific wafers out of a plurality of wafers attached to the block may be deformed. Specifically, FIG.
As shown in FIG. 5, for example, five wafers a, b, c, d, and e
Is adhered to one block 4 and polished, a taper (referred to as side taper defect) occurs in the circumferential direction as in wafers a and b, or it is hardly polished as in wafer d. Is a phenomenon. FIG. 9 shows a state in which the block is turned upside down after polishing so that the wafer faces upward. Further, this figure is exaggeratedly shown for easy understanding of defects such as side taper of the wafer, and the actual side taper defect is about 2 μm.

[0006] Such a phenomenon occurs in the case of the device described in the above-mentioned publication because, for example, due to the accuracy of the elastic tube, even if the pressure applied to the block itself is equalized, individual individual parts are locally formed in the block plane. This occurs because the force holding the wafer is different. In addition, such a phenomenon is not limited to the apparatus described in the above publication, but the flatness of the block is made as flat as possible at the current technical level, and the pressing force of the entire block is averaged by adjusting the pressing mechanism. This is a problem that occurs even when the wafers are operated in a modified manner, and it is desired to eliminate the side taper defect in order to increase the yield in the wafer mirror polishing step.

Accordingly, an object of the present invention is to provide a polishing apparatus and a polishing method capable of suppressing the occurrence of the above-described side taper failure due to uneven pressure in the circumferential direction in which the block rotates. is there.

[0008]

According to a first aspect of the present invention, there is provided a block for holding a material to be polished, and a block facing the side of the block holding the material to be polished. A surface plate with a polishing pad attached to the surface to be
Pressing means for pressing the block against the platen,
In a polishing apparatus having a sliding drive unit that relatively slides the block and the surface plate, a sliding member is provided between the block and the pressing unit, and during polishing of the workpiece, A polishing apparatus, wherein the block and the pressurizing means are relatively slidable.

According to the present invention, by providing a sliding member between the block and the pressurizing means, the block slides with respect to the rotation of the pressurizing means, so that the block does not completely follow the rotation of the pressurizing means. The block slides and rotates relatively to the pressing means. As a result, the position of the block slightly shifts with respect to the rotation of the pressing means. The pressing force in the circumferential direction over the entire block becomes uniform.

The present invention described in claim 2 is the same as the claim 1.
The polishing apparatus according to claim 1, wherein the polishing apparatus further comprises:
It is characterized in that the polishing apparatus has a sliding amount control means for keeping a relative sliding amount between the block and the pressing means constant during polishing of the workpiece.

According to the present invention, in the configuration according to the first aspect, wherein a sliding member is provided between the block and the pressing means, the control means controls the relative sliding amount of the block with respect to the pressing means.

[0012] In order to achieve the above object, a third aspect is provided.
The present invention according to the present invention provides a block for holding a material to be polished, a platen having a polishing pad attached to a surface of the block arranged opposite to the side holding the material to be polished, and In a polishing apparatus having a pressing means for pressing against a plate and a sliding drive means for relatively sliding the block and the platen, during polishing of the material to be polished, A polishing apparatus characterized by having a pressure control means capable of arbitrarily changing the pressure.

According to the present invention, the pressing force of the pressurizing means is arbitrarily varied so that the pressing force is temporarily reduced, during which the block rotates idly with respect to the pressurizing means. As a result, the position of the block slightly shifts with respect to the rotation of the pressing means. The pressing force in the circumferential direction over the entire block becomes uniform.

According to a fourth aspect of the present invention for achieving the above object, a block for holding an object to be polished is provided on a surface of the block facing the side for holding the object to be polished. A polishing apparatus having a surface plate to which a polishing pad is attached, a pressing unit for pressing the block against the surface plate, and a sliding drive unit for relatively sliding the block and the surface plate. A polishing method for polishing the surface of the material to be polished by pressing and sliding the material to be polished against a polishing pad, wherein the pressing force of the pressing means is changed during polishing of the material to be polished. This is a polishing method characterized in that polishing is performed while the polishing is performed.

According to the present invention, by changing the pressing force of the pressing means, the pressing force is temporarily reduced during polishing, and the block is caused to idle with respect to the pressing means during the polishing. As a result, the position of the block slightly shifts with respect to the rotation of the pressing means. The pressing force in the circumferential direction over the entire block becomes uniform.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a side view showing the overall schematic configuration of a polishing apparatus according to an embodiment of the present invention.

As shown in FIG. 1, the present polishing apparatus comprises a block 4 for holding a silicon wafer 5 as a material to be polished.
And a platen 9 is arranged opposite to the side of the block 4 holding the silicon wafer 5. As a pressing means for pressing the silicon wafer 5 held by the block 4 against a surface plate 9 having a polishing pad 6 adhered to the surface, a pressing shaft 1 moving up and down, A pressurizing head 3 is provided so as to swing and rotate freely. The platen 9 is a drive mechanism 3 including a motor and a speed reducer.
On the other hand, the pressurizing head 3 presses the silicon wafer 5 against the polishing pad 6 by the pressurizing drive mechanism 32 rotating and moving the pressurizing shaft 1 up and down, and slides.

An abrasive is supplied to the polishing pad 6 on the surface plate 9 from an abrasive supply nozzle 17 disposed above and substantially at the center of the surface plate 9.
Is mirror-polished by pressing and sliding against the polishing pad 6.

Further, in the present polishing apparatus, in order to detect deformation due to frictional heat or the like during polishing of the block 4, the electric micrometer 33 is provided near the center in the radial direction of the block 4 and at both outer edges of a diameter passing therethrough. It is supported by the arm 38 at a total of three places including the vicinity of the section, and is provided so as to penetrate the pressure head 3 and come into contact with the upper surface of the block 4 to detect a displacement in the block thickness direction. Here, the surface shapes of the upper surface and the lower surface of the block 4 are precisely measured in advance, and by detecting the displacement of the upper surface of the block 4 from the initial shape as described above, the side on which the silicon wafer 5 is pressed is detected. The surface shape of the block 4 can always be detected. Thus, the deformation of the block in the radial direction with respect to the entire block during operation is detected.

In the present polishing apparatus, three eddy current displacement sensors 34 are provided from the center to the outer periphery of the surface plate 9. The eddy current displacement sensor 34 is supported by an arm (not shown) so that the height to the measurement surface and the movement of the measurement position can be finely adjusted as appropriate. The eddy current type displacement sensor 34 makes the coil to which the alternating current flows approach the surface plate 9 which is a metal body, and utilizes the fact that the impedance of the coil changes depending on the distance from the surface plate 9. It measures displacement. For this reason, a polishing pad 6 which is a non-magnetic material and a polishing liquid (silica, water, etc.)
Even if there is, it is possible to directly measure the displacement of the surface plate 9 without being affected by these. In addition, the surface shape of the upper surface of the surface plate 9 is precisely measured in advance, and the displacement of the upper surface of the surface plate 9 is changed from time to time by detecting the displacement from the initial shape of the upper surface of the surface plate 9 as described above. The surface shape can be detected.

Further, the present polishing apparatus has a water cooling mechanism (not shown) for flowing water or other coolant into the surface plate 9 so that the temperature of the surface plate 9 does not become abnormally high due to frictional heat during polishing. Is provided. In this water cooling mechanism, the amount of cooling water flowing to the water cooling mechanism in the surface plate 9 is adjusted by the cooling water amount adjusting mechanism 36.

On the other hand, below the pressure head 3, there is provided a block pressing portion 37 for pressing the block 4 and arbitrarily changing its surface shape in the radial direction. The pressing force is appropriately adjusted based on the detected amount of deformation of the block.

Further, in the present polishing apparatus, a sliding member 40 having a low coefficient of friction is inserted between the block pressing portion 37 and the block 4 as described later (see FIGS. 2 and 3). By the insertion of the sliding member 40, the block 4 slides and rotates relatively to the rotation of the pressure head 3.

FIG. 2 is an enlarged side view of the vicinity of the block pressing portion of the present apparatus, and FIG. 3 is a view seen from A in FIG.

As shown in FIG. 2, the block pressing section 37
Is a central pressing part 37a for pressing the central part of the block 4.
And a ring-shaped outer edge pressing portion 37b for pressing the vicinity of the outer edge portion of the block 4, each of which is formed by filling a fluid into an elastic tube made of, for example, heat-resistant silicon rubber.

A sliding member 40 having a low coefficient of friction is attached to both the center pressing portion 37a and the outer edge pressing portion 37b so as to be inserted between the block 4 and the block 4. Have been. Due to the insertion of the sliding member 40, when the block 4 rotates with the rotation of the pressure head 3, the block 4 rotates with a slight deviation from the rotation of the pressure head 3. This is shown in FIG. At some point, assuming that the wafer a is at the position shown in FIG. 4A, after a certain period of time, for example, when the pressure head 3 rotates several times,
As shown in (B), the position of the wafer a is slightly delayed from the rotational position of the pressure head 3.

That is, the block 4 is relatively slid and rotated relative to the rotation of the pressure head 3, so that even if a local pressure is applied to the block 4, the wafer 5 With the rotation of the pressure head 3, the position where the local pressure is applied gradually shifts, and the phenomenon that the local pressure is always applied only to a specific wafer is eliminated. Therefore, as a final polishing finish of the wafer, a uniform pressure is applied to all of the plurality of wafers attached to the block 4, and a side taper defect occurring for a specific wafer does not occur.

As the sliding member 40, the pressure applied to the block 4 by the pressing head 3 during polishing, for example, 100
For a range of to 300 g / cm ^2, is of a low coefficient of friction such as sliding across occurs, the friction coefficient is 0.1
Preferably, the material is about 0.2 to 0.2, and as such a material, for example, Teflon or Delrin is suitable.

The relative sliding amount of the block 4 with respect to the pressure head 3 changes depending on the friction coefficient of the sliding member 40 and the friction coefficient between the wafer 5 and the polishing pad 6 on the surface plate 9. If the rotation direction of the platen 9 and the rotation direction of the block 4 are the same, for example, if the friction coefficient of the sliding member 40 is higher than the friction coefficient between the wafer 5 and the polishing pad 6, as shown in FIG. The rotation of the block 4 rotates a little later than the rotation of the pressure head 3. Conversely, if the friction coefficient of the sliding member 40 is lower than the friction coefficient between the wafer 5 and the polishing pad 6, the rotation of the platen 9 As a result, the block 4 rotates slightly faster than the pressure head 3.

The pressure applied by the block pressurizing unit 37 is adjusted by a pressurizing distribution adjusting mechanism 35 (see FIG. 1).
Has a function of changing the ratio of the pressure values of the central pressing portion 37a and the outer edge pressing portion 37b. The pressing mechanism moves the block 4 toward the platen 9 to provide a difference between the center portion and the outer edge portion. By pressing, the surface shape of the block 4 can be changed.

By the function of the pressure distribution adjusting mechanism 35,
For example, as shown in FIG. 5, the pressure value of the central pressing portion is made larger than a predetermined ratio, and the block 4 is deformed to have a lower surface convex shape. The shape can be changed (this state is not shown). Thereby, the shape of the block 4 measured by the micrometer 33 and the displacement sensor 3
By changing the shape of the block 4 in accordance with the shape of the surface plate 9 measured by 4, the shape in the block radial direction is changed, and the silicon wafer 5 is polished so as to be inclined and thinner to the outer peripheral side of the block 4. This prevents a tapered state (also referred to as "outside deviation") or a tapered state (also referred to as "inside deviation") in which the silicon wafer 5 is polished so as to be inclined toward the center of the block 4 and become thin. be able to.

The control of the pressure distribution adjusting mechanism 35 is performed by the pressure control unit 30. The pressure control unit 30 controls the displacement amount in the block thickness direction detected by the micrometer 33 and the displacement sensor 34. The detected amount of displacement of the surface plate in the thickness direction is input, and based on these, the pressure distribution adjusting mechanism 35 is operated to adjust the pressure at the center of the block and the outer edge.

The detailed configuration and function of the pressure control unit 30, the pressure distribution adjusting mechanism 35, the block pressure unit 37, the micrometer 33, the displacement sensor 34, and the water cooling mechanism are described in Japanese Patent Application No. 8-4830. Therefore, detailed description is omitted.

In the first embodiment described above, the center pressing portion 37a and the outer edge pressing portion 37 of the block pressing portion 37 are used.
Although the sliding member 40 is configured to be attached to each of the b, the present invention is not limited to such a configuration. For example, the displacement amount of the block 4 is measured without using the micrometer contacting the block as described above. In such a case, a sheet-like low coefficient of friction member may be laid on the entire surface of the block 4 on the block pressing portion 37 side (that is, the side on which the wafer is not attached) as a sliding member. In addition to using a member having a low friction coefficient as the sliding member, a ball bearing is provided in each of the center pressing portion 37a and the outer edge pressing portion 37b of the block pressing portion 37, and the block is formed with respect to the pressing head 3. You may make it freely rotatable.

Second Embodiment In the first embodiment described above, the block 4 rotates relative to the pressure head 3 due to the friction coefficient of the sliding member. The rotation is due to slippage with the sliding member, so that the rotation occurs randomly. In the second embodiment, the relative rotation of the block 4 with respect to the pressure head 3 is controlled.

The basic configuration of the apparatus according to the second embodiment is the same as that of the first embodiment, and therefore, only the parts different from the first embodiment will be described.

FIG. 6 is a view of a part of the surface plate 9 and the block 4 as viewed from the pressure head side. As shown in the figure, in the second embodiment, a guide 51 is provided on the outer peripheral portion of the surface plate 9 as a sliding amount control means for controlling the sliding amount of the block 4 with respect to the pressure head 3. An idle member 45 is provided in contact with the outer peripheral portion, and the number of rotations is reduced as the platen 9 rotates, so that the block 4 is rotated. The center pressing portion 37a of the block 4 and the block pressing portion 37 and the outer edge pressing portion 37
As in the first embodiment, a sliding member 40 or a ball bearing or the like is inserted between the sliding member 40 and b.

As described above, the idle member 45 is used to reduce the rotation speed of the block 4 with respect to the rotation speed of the platen 9. Can be changed arbitrarily.
As shown in FIG. 7, the idle member 45 is supported by the arm 101 from the pedestal 100 of the polishing apparatus. The idle member 45 can be retracted outside during operation so that it does not hinder replacement of the block 4 or the like. I have. In addition to the support from the pedestal, the support may be supported from the rotation mechanism side of the press block 3 that suspends and supports the press block 3.

In the second embodiment, the rotation direction of the platen 9 is opposite to the rotation direction of the pressure head 3, and the rotation direction of the block 4 is the same as that of the pressure head 3. The size of the idle member 45 is selected so as to rotate slightly later than 3. If the pressure head 3 and the platen 9 rotate in the same direction, two idle members are connected and inserted between the guide 51 and the block 4. Also,
Instead of such a roller type idle member 45,
For example, the rotation of the block 4 may be controlled by a gear mechanism by using an idle gear and providing internal teeth inside the guide 51 on the outer periphery of the surface plate and external teeth on the outer periphery of the block.

By controlling the relative sliding amount of the block 4 with respect to the pressing head 3 in this manner, even if a local pressure is applied in any of the blocks, a plurality of wafers can be controlled. As a result, a uniform pressure is always applied, and defects such as side taper can be prevented.

<< Embodiment 3 >> In Embodiments 1 and 2 described above, a sliding member is used between the block 4 and the center pressing portion 37a and the outer edge pressing portion 37b of the block pressing portion 37, and the sliding member is used. Although the pressure head 3 and the block 4 are relatively slid and rotated by slipping, in the third embodiment, the pressure head 3 and the block 4 are moved without using such a sliding member. It is designed to relatively slide and rotate.

The configuration of the polishing apparatus according to the third embodiment is as follows.
As shown in FIG. 8, unlike Embodiments 1 and 2 described above, there is no sliding member, and the central pressing portion 37a and the outer edge pressing portion 37b of the block pressing portion 37 provided on the pressing head 3 are not provided. This is a configuration in direct contact with the block 4. Therefore, other configurations are the same as in the first embodiment.

Then, the entire pressure block 3 is replaced with a block 4
During the polishing operation, the pressing shaft 1 (see FIG. 1) that presses in the direction is slightly moved up and down, and when the pressing shaft 1 moves upward,
That is, when the pressing force becomes slightly low, the block 4 idles, and the block 4 moves relatively to the pressure head 3.

The vertical movement of the pressure shaft 1 for raising and lowering the pressure head 3 during polishing is performed by moving the cylinder of the pressure drive mechanism 32 up and down under the control of the pressure control unit 30.

The size of the vertical movement of the pressure head 3 is about 1 to 2 mm, and the block can be rotated only slightly, without following the pressure head. May be periodic or random, for example, one of the pressure heads 3
For example, once every rotation, once every 10 rotations, or once or twice irregularly.

As described above, the pressing force of the pressure head 3 is temporarily loosened during polishing, so that the block 4 is made to idle, and the block 4 rotates and moves relatively to the pressure head 3. Even when a local pressure is applied to any of the wafers, a uniform pressure is always applied to a plurality of wafers, and defects such as side taper can be prevented.

Although the embodiments of the present invention have been described above, the present invention is not limited to each of the embodiments. Therefore, each element disclosed in each of the above embodiments is intended to include all design changes and equivalents belonging to the technical scope of the present invention. For example, in each of the above-described embodiments, the pressure applied to the block 4 in the radial direction is variable. However, other than such a configuration, the pressure head 3 directly presses the block 4. In the structure, the sliding member 40 can be inserted between the pressing head 3 and the block 4 or the pressing force can be temporarily reduced to thereby implement the pressing force in the circumferential direction with respect to the rotation of the pressing head 3. Is obtained. Further, the present invention can be suitably used not only for a polishing apparatus for silicon wafers, but also for a polishing apparatus for other compound semiconductor wafers and a polishing apparatus other than mirror polishing, for example, for lapping polishing.

[0048]

According to the present invention described above, the following effects can be obtained for each claim.

According to the first aspect of the present invention, since the block slides and rotates relatively to the pressurizing means, even if there is a locally uneven pressing force, By the relative rotation of the block, the pressing force applied to each of the plurality of polished materials until the polishing of the polished materials is completed becomes uniform, eliminating partial polishing defects such as side taper and the like, and having high flatness. Polishing becomes possible.

According to the second aspect of the present invention, since the relative sliding amount of the block with respect to the pressurizing means is controlled, there is no difference between batches in batch processing.
Pressurization in the circumferential direction can be performed with the same uniformity in any batch, and variation in polishing finish between batches can be suppressed.

According to the third aspect of the present invention, during the polishing, the pressure of the pressurizing means is arbitrarily changed, and during the polishing, the pressure is temporarily loosened so that the block is moved relative to the pressurizing means. Because it was possible to slide and rotate relatively,
Even if there is an uneven portion of the local pressing force, the pressing force applied to each of the plurality of polished materials becomes uniform by the relative rotation of the block until the polishing of the polished material is completed. Partial polishing defects such as taper can be eliminated, and polishing with high flatness can be performed.

According to the present invention, the pressing force of the pressing means is changed during polishing.
When the pressure is temporarily reduced during polishing, the block can rotate relative to the pressing means, and the position of the material to be polished attached to the block moves,
The pressing force applied to each of the plurality of polished materials until the polishing of the polished materials is completed becomes uniform, and partial polishing defects such as side taper can be eliminated, and polishing with high flatness can be performed.

[Brief description of the drawings]

FIG. 1 is a side view showing a schematic configuration of a polishing apparatus according to Embodiment 1 of the present invention.

FIG. 2 is an enlarged side view around a block pressing unit of the present apparatus.

FIG. 3 is a view as seen from A in FIG. 2;

FIG. 4 is a view for explaining relative sliding and rotation of a block with respect to a pressure head during polishing in the present apparatus.

FIG. 5 is a drawing for explaining a deformation of a block when a pressing force of a central portion and an outer edge portion by a block pressing portion in the present apparatus is changed.

FIG. 6 is a plan view of a block on a surface plate of a polishing apparatus according to Embodiment 2 of the present invention, as viewed from a pressure head side.

FIG. 7 is an enlarged side view of a peripheral portion of a block of the present apparatus.

FIG. 8 is an enlarged side view around a block pressing portion of a polishing apparatus according to Embodiment 3 of the present invention.

FIG. 9 is a drawing for explaining a wafer in which a side taper defect or the like has occurred.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Press shaft, 3 ... Press head, 4 ... Block, 5 ... Silicon wafer, 6 ... Polishing pad, 9 ... Surface plate, 37 ... Block press part, 37a ... Central press part, 37b ... Outer edge press Part, 40: sliding member, 45: idler member, 51: guide.

Claims (4)

[Claims] 1. A block for holding a material to be polished, a platen having a polishing pad attached to a surface of the block facing the side holding the material to be polished, and the platen In a polishing apparatus having a pressing means for pressing against and a sliding driving means for relatively sliding the block and the surface plate, a sliding member is provided between the block and the pressing means. A polishing apparatus, wherein the block and the pressing means are relatively slidable during polishing of the material to be polished. 2. The polishing apparatus according to claim 1, further comprising a sliding amount control means for keeping a relative sliding amount between said block and said pressing means constant during polishing of said material to be polished. The polishing apparatus according to claim 1, wherein 3. A block for holding an object to be polished, a platen having a polishing pad attached to a surface of the block facing the side of the block holding the object to be polished; A polishing means having a pressing means for pressing against the surface of the workpiece and a sliding drive means for relatively sliding the block and the surface plate. A polishing apparatus comprising pressure control means capable of arbitrarily changing a pressure. 4. A block for holding a material to be polished, a platen having a polishing pad attached to a surface of the block facing the side holding the material to be polished, and Using a polishing apparatus having a pressurizing means for pressurizing the workpiece and a sliding driving means for relatively sliding the block and the platen, and pressing the polishing target against a polishing pad. A polishing method for polishing a surface of a material to be polished by moving, wherein the polishing is performed while changing the pressing force of the pressurizing means during the polishing of the material to be polished.