JP2940613B2 - Wafer polishing equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly, to a chemical mechanical polishing method (CMP).
ical Polishing).

[0002]

2. Description of the Related Art A wafer polishing apparatus disclosed in Japanese Patent Application Laid-Open No. 8-339979 includes a holding head (carrier), a polishing pad (polishing cloth), and a seal member. A fluid supply path is formed in the holding head, and from this fluid supply path,
A pressurized fluid is supplied to a space surrounded by the holding head, the substrate (wafer), and the seal member, and the substrate is polished by pressing the substrate against the polishing pad with the pressurized fluid.

Further, an annular guide member is attached to the holding head of the wafer polishing apparatus. This guide member is pressed against the polishing pad together with the substrate,
The substrate is prevented from jumping out of the holding head due to centrifugal force.

[0004]

SUMMARY OF THE INVENTION
Since the wafer polishing apparatus disclosed in the publication 8-339979 only presses the substrate against the polishing pad with a pressure fluid,
There is a disadvantage that the polishing pressure applied to the wafer from the polishing pad is concentrated on the periphery of the substrate, that is, the polishing pad rises at the periphery of the substrate, and the periphery is polished more than other portions.

The present invention has been made in view of such circumstances, and has as its object to provide a wafer polishing apparatus capable of uniformly polishing the entire surface of a wafer by making the polishing pressure applied to the wafer from a polishing cloth uniform. And

[0006]

According to the present invention, in order to achieve the above object, a wafer is pressed against a rotating polishing cloth,
In a wafer polishing apparatus for polishing the surface of a wafer,
A carrier that holds the wafer and presses the wafer against the polishing cloth, a polishing surface adjustment ring that surrounds the periphery of the wafer and is pressed against the polishing cloth together with the wafer,
Pressing means for pressing the polishing surface adjustment ring against the polishing cloth, and carrying the polishing surface adjustment ring with respect to the polishing cloth ,
A , the position detecting means for detecting the relative position of the polishing surface adjustment ring, and the sinking position detected by the position detecting means, so that the polishing pressure applied to the wafer from the polishing cloth is located at a position where the polishing pressure is uniform. Control means for controlling the pressing force of the pressing means.

According to another aspect of the present invention, there is provided a wafer polishing apparatus for polishing a surface of a wafer by pressing the wafer against a rotating polishing pad. Forming a pressurized air layer between the carrier and the wafer; pressing force from the first presser to the wafer via the pressurized air layer; Pressure air layer forming means, a retainer ring provided outside the carrier to prevent the wafer from jumping out of the carrier, and a polishing surface provided outside the retainer ring and in contact with the polishing cloth together with the wafer. An adjusting ring, second pressing means for pressing the polishing surface adjusting ring against the polishing cloth, and sinking of the polishing surface adjusting ring with respect to the polishing cloth Position detecting means for detecting the position, and controlling the pressing force by the second pressing means such that the sinking position detected by the position detecting means is located at a position where the polishing pressure applied to the wafer from the polishing cloth is uniform. And control means for performing the operation.

Further, in order to achieve the above object, the present invention provides a wafer polishing apparatus for polishing a surface of a wafer by pressing the surface of the wafer against a rotating polishing cloth; First pressing means for pressing the polishing pad toward the polishing cloth, and supplying air between the carrier and the wafer to form a pressure air layer. The pressing force from the first pressing means is applied to the pressure air layer. Pressure air layer forming means for transmitting to the wafer through the carrier, a retainer ring provided outside the carrier to prevent the wafer from jumping out of the carrier, and a polishing cloth provided outside the retainer ring together with the wafer. A polishing surface adjusting ring that is in contact with the polishing surface; a second pressing unit that presses the polishing surface adjusting ring against the polishing cloth; And a pressing member that is pressed against the polishing surface adjustment ring and is brought into contact with the flattened polishing cloth, and is provided on the pressing member, and controls a relative displacement between the pressing member and the carrier. Detect
Position detecting means for detecting a submerged position of the polishing surface adjustment ring with respect to the polishing cloth based on the relative displacement, and the submerged position detected by the position detecting means makes the polishing pressure applied to the wafer from the polishing cloth uniform. Control means for controlling the pressing force of the second pressing means so as to be located at the position,
Characterized by the following.

According to the first aspect of the present invention, the wafer is polished by pressing the wafer against the polishing cloth with the carrier. At this time, while pressing the polishing surface adjustment ring against the polishing cloth by pressing means,
The pressing means is controlled by the control means, and the wafer is polished by setting the sinking position of the polishing surface adjusting ring with respect to the polishing cloth to a position where the polishing pressure applied from the polishing cloth to the wafer becomes uniform. Thus, according to the present invention, the polishing pressure applied to the wafer from the polishing cloth becomes uniform, so that the entire surface of the wafer can be uniformly polished.

According to the second aspect of the present invention, a pressure air layer is formed between the carrier and the wafer by the pressure air layer forming means, and the pressing force from the first pressing means is applied to the wafer through the pressure air layer. Then, the wafer is pressed against the polishing pad and polished. Thereby, the present invention
The pressing force from the first pressing means can be uniformly transmitted to the entire surface of the wafer even if there is foreign matter such as polishing dust between the carrier and the wafer, so that the entire surface of the wafer can be uniformly polished.

According to a second aspect of the present invention, there is provided a polishing surface adjusting ring which comes into contact with the polishing cloth together with the wafer, and the pressing force of the polishing surface adjusting ring against the polishing cloth is adjusted by the second pressing means. (2) The wafer is polished by controlling the pressing means by the control means so that the submerged position of the polishing surface adjusting ring with respect to the polishing cloth is located at a position where the polishing pressure applied to the wafer from the polishing cloth becomes uniform. Thus, according to the present invention, the polishing pressure applied to the wafer from the polishing cloth becomes uniform, so that the entire surface of the wafer can be further uniformly polished.

According to the third aspect of the present invention, the pressing member pressed against the polishing pad together with the wafer is provided with position detecting means, and the position detecting means detects the relative displacement between the pressing member and the carrier, thereby enabling polishing. The submersion position of the polishing surface adjustment ring with respect to the cloth is detected. Then, the second pressing means is controlled by the control means, and the wafer is polished by positioning the sinking position of the polishing surface adjusting ring with respect to the polishing cloth at a position where the polishing pressure applied to the wafer from the polishing cloth becomes uniform. Thus, according to the present invention, the polishing pressure applied to the wafer from the polishing cloth becomes uniform, so that the entire surface of the wafer can be uniformly polished. Further, the pressing member,
Since the pressing member is in contact with the polishing cloth leveled by the polishing surface adjusting ring, the pressing member does not vibrate up and down due to the uneven surface of the polishing cloth. Therefore, the position detecting means attached to the pressing member can accurately detect the sinking position of the polishing surface adjustment ring with respect to the polishing cloth.

[0013] The invention according to claims 4 to 6 is characterized in that a differential transformer having a core and a bobbin is applied as the position detecting means. Thereby, the sinking position of the polishing surface adjustment ring with respect to the polishing cloth can be accurately detected. The invention according to claims 7 to 9 is characterized in that a capacitance sensor is applied as the position detecting means. Thereby, the sinking position of the polishing surface adjustment ring with respect to the polishing cloth can be accurately detected.

According to a tenth aspect of the present invention, the pressing member is made of a low thermal expansion material, and the contact surface of the pressing member is made of diamond coating or ceramic. Thus, the pressing member does not thermally expand during polishing of the wafer, and is not polished by the polishing cloth. Therefore, the polishing amount detecting means attached to the pressing member can accurately detect the position where the polishing surface adjusting ring sinks into the polishing cloth.

The invention according to claims 11 and 12 is characterized in that the retainer ring is made of a softer material than the polished surface adjusting ring. The polishing surface adjusting ring is made of a material harder than the polishing cloth because the polishing cloth is pressed against the polishing cloth to elastically deform the polishing cloth. When the wafer is prevented from jumping out of the carrier with such a hard polishing surface adjusting ring, the wafer may be damaged when the wafer comes into contact with the polishing surface adjusting ring. Therefore, in the present invention, in order to solve such a problem, the retainer ring is made of a softer material than the polished surface adjustment ring. Thus, the present invention can prevent breakage of the wafer that occurs when the wafer comes into contact with the retainer ring.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a wafer polishing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is an overall configuration diagram of a wafer polishing apparatus according to an embodiment of the present invention. As shown in FIG. 1, the wafer polishing apparatus 10 mainly includes a polishing platen 12 and a wafer holding head 14. The polishing platen 12 is formed in a disk shape, and a polishing cloth 16 is provided on an upper surface thereof. A spindle 18 is provided below the polishing platen 12.
The spindle 18 is connected to an output shaft (not shown) of the motor 20. The polishing platen 12 rotates in the direction of arrow A by driving a motor 20, and a slurry is supplied from a nozzle (not shown) onto the polishing cloth 16 of the rotating polishing platen 12. The wafer holding head 14 is provided so as to be vertically movable by an elevating device (not shown), and is moved up when a wafer to be polished is set on the wafer holding head 14. Further, the wafer holding head 14 is moved downward when polishing the wafer, and is pressed against the polishing cloth 16.

FIG. 2 is a longitudinal sectional view of the wafer holding head 14. The wafer holding head 14 shown in FIG. 1 includes a head body 22, a carrier 24, a guide ring 26, a polishing surface adjustment ring 28, a rubber sheet 30, and the like. The head body 22 is formed in a disk shape,
The motor 2 is rotated in the direction of arrow B by a motor (not shown) connected to the motor 2. The air supply path 3 is provided in the head body 22.
4 and 36 are formed. The air supply path 34 extends outside the wafer holding head 14 as shown by a two-dot chain line in FIG. 2 and has a regulator (R) 38A.
To an air pump (AP) 40. The air supply path 36 is connected to an air pump 40 via a regulator 38B.

The carrier 24 is formed in a substantially columnar shape, and is disposed coaxially with the head main body 22 below the head main body 22. Further, a concave portion 25 is provided on the lower surface of the carrier 24.
Are formed, and the porous plate 4 having air permeability is formed in the concave portion 25.
2 are stored. The air chamber 2 is located above the porous plate 42.
The air chamber 27 is communicated with an air suction path 44 formed in the carrier 24. The air suction path 44 extends outside the wafer holding head 14 as shown by a two-dot chain line in FIG.
suction pump) 46. Therefore, when the suction pump 46 is driven, the wafer 50 is sucked by the porous plate 42 and held by suction on the lower surface of the porous plate 42. The porous plate 42 has a number of air passages therein, and for example, a porous plate made of a sintered body of a ceramic material is used.

The carrier 24 has a number of air supply paths 48, 48,.
(Only two locations are shown in FIG. 2). The air supply paths 48 extend outside the wafer holding head 14 as shown by a two-dot chain line in FIG. 2 and are connected to the air pump 40 via a regulator 38C. Therefore, when the air pump 40 is driven, the air pump 4
Compressed air from 0 is blown out into the air chamber 51 between the porous plate 42 and the wafer 50 via the air supply passages 48, 48. Accordingly, a pressure air layer is formed in the air chamber 51, and the pressing force of the carrier 24 is transmitted to the wafer 50 via the pressure air layer. The wafer 50 is moved by the pressing force transmitted through the pressure air layer to the polishing pad 1.
Pressed to 6.

The wafer holding head 14 controls the pressing force applied to the carrier 24 to move the carrier 24 up and down, thereby controlling the polishing pressure of the wafer 50 (the force for pressing the wafer 50 against the polishing pad 16). Therefore, the control of the polishing pressure is easier than the control of the polishing pressure of the wafer 50 by controlling the pressure of the pressure air layer. That is, in the wafer holding head 14, the polishing pressure of the wafer 50 can be controlled only by controlling the vertical position of the carrier 24. The air supply paths 48, 4
8 are exhausted to the outside through exhaust holes (not shown) formed in the polishing surface adjusting ring 28.

The carrier 24 has a large number of air / water supply passages 5 each having an ejection port formed on the lower surface of the carrier 24.
2, 52... (Only two locations are shown in FIG. 2).
The air / water supply paths 52 extend outside the wafer holding head 14 as shown by a two-dot chain line in the figure, and are branched in two directions via a valve 54. An air pump 40 is connected to one branch via a regulator 38D, and a water pump (W
P (water pump) 56 is connected. Therefore,
When the path on the air pump 40 side is opened by the valve 54 and the path on the water pump 56 side is closed, the air pump 40
Are supplied to the air chamber 51 through air / water supply passages 52, 52. Also, the valve 54
Is switched to close the path on the air pump 40 side and open the path on the water pump 56 side, the water pump 56
Is supplied to the air chamber 51 via air / water supply passages 52, 52...

On the other hand, one rubber sheet 30 is disposed between the carrier 24 and the head main body 22. This rubber sheet 30 is formed in a disk shape with a uniform thickness. The rubber sheet 30 is fixed to the lower surface of the head body 22 by an annular stopper 58, and the rubber sheet 30 is divided into a center part 30 </ b> A and an outer peripheral part 30 </ b> B with the stopper 58 as a boundary. The center 30A of the rubber sheet 30 is the carrier 2
The outer peripheral portion 30B functions as an airbag that presses the polishing surface adjustment ring 28.

Below the head body 22, a rubber sheet 3
A space 60 which is hermetically sealed by the central portion 30 </ b> A and the stopper 58 is formed. The air supply path 36 communicates with the space 60. Therefore, when compressed air is supplied from the air supply path 36 to the space 60, the central portion 30A of the rubber sheet 30 is elastically deformed by air pressure and presses the upper surface of the carrier 24. Thereby, a pressing force of the wafer 50 against the polishing pad 16 can be obtained. Further, if the air pressure is adjusted by the regulator 38B, the pressing force (polishing pressure) of the wafer 50 can be controlled.

The guide ring 26 is formed in a cylindrical shape, and is disposed coaxially with the head main body 22 below the head main body 22. In addition, the guide ring 26 is attached to the rubber sheet 3.
0 is fixed to the head main body 22. A polishing surface adjusting ring 28 is disposed between the guide ring 26 and the carrier 24. A retainer ring 62 for preventing the wafer 50 from jumping out is attached to the lower inner peripheral portion of the polishing surface adjusting ring 28. The retainer ring 62 is made of a material softer than the polished surface adjustment ring 28, for example, rubber, resin, or the like. Thereby, even if the wafer 50 abuts on the retainer ring 62, the wafer 5
0 does not break.

An annular space 64 is formed in the lower outer peripheral portion of the head main body 22 so as to be sealed by the outer peripheral portion 30B of the head main body 22 and the rubber sheet 30 and the like. This space 6
4 communicates with the air supply path 34. Therefore, when compressed air is supplied from the air supply path 34 to the space 64, the outer peripheral portion 30B of the rubber sheet 30 is elastically deformed by air pressure and presses the annular upper surface of the polishing surface adjustment ring 28. Thereby, the annular lower surface (contact surface) of the polishing surface adjusting ring 28
29 is pressed against the polishing pad 16. The pressing force of the polishing surface adjusting ring 28 can be controlled by adjusting the air pressure with the regulator 38A.

On the other hand, the wafer holding head 14 has
A detection device for detecting the polishing amount of the wafer 50 is provided. This detection device comprises a sensor 70 comprising a core 66 and a bobbin 68, and non-contact sensors 72, 72, 72. These sensors 70, 72, 72, 7
A CPU (shown in FIG. 3) 74 for performing arithmetic processing on the detection value detected in Step 2 is provided outside the wafer holding head 14.

In FIG. 2, the sensor 70 is a differential transformer, and a bobbin 68 constituting the differential transformer.
Is attached to the tip of an arm 76 extending from the inner surface of the polishing surface adjusting ring 28 in the direction of the rotation axis of the wafer holding head 14. The core 66 of the sensor 70
Are arranged at positions where the center axis of the core 66 is coaxial with the rotation axis of the wafer holding head 14. The sensor 70 can detect the amount of vertical movement of the carrier 24 with respect to the contact surface 29 of the polishing surface adjustment ring 28, and also detects the sinking position of the polishing surface adjustment ring 28 with respect to the surface of the polishing pad 16. be able to. In addition,
The carrier 24 has a groove 78 into which the arm 76 is inserted.

Although the polishing amount of the wafer 50 can be generally detected by the sensor 70, in the present embodiment, the detected value detected by the sensor 70 is
The amount of polishing of the wafer 50 is accurately obtained by correcting with the detection values detected in steps 2 and 72. The sensor 72 is a non-contact sensor such as a capacitance sensor, the detection surface 72A of which is arranged flush with the lower surface of the porous plate 42,
By detecting the distance from the upper surface of the wafer 50, the fluctuation amount of the layer thickness of the pressure air layer (air chamber 51) is detected.

The CPU 74 shown in FIG. 3, which controls the wafer polishing apparatus, controls the amount of change in the thickness of the pressure air layer detected by the sensors 72, 72, 72 based on the amount of change in the carrier 24 detected by the sensor 70. Is added to calculate the polishing amount of the wafer 50. That is, the CPU 74 calculates the polishing amount of the wafer 50 from the fluctuation amount with respect to the reference value stored in the RAM 75 in advance. For example, sensor 7
The fluctuation amount detected at 0 is T1, and the sensors 72, 72, 7
If the average value of the fluctuation amounts detected in Step 2 is T2, the polishing amount of the wafer 50 at that time is calculated by T1 + T2. Further, the amount of fluctuation from the sensor 70 is T1, and the sensors 72, 7
If the average value of the fluctuation amounts from 2, 72 is 0, the polishing amount of the wafer 50 at that time is calculated by T1-0. Further, the fluctuation amount from the sensor 70 is T1, and the sensors 72, 72, 7
If the average value of the variation from 2 is -T2, the polishing amount of the wafer 50 at that time is calculated by T1-T2. As described above, in the present embodiment, the sensors 70 and 72 are provided to calculate the polishing amount from the two fluctuation amounts, so that the polishing amount of the wafer 50 can be accurately measured. Also,
Since the thickness of the processed wafer is a known thickness, the polishing surface adjusting ring 2 for the wafer polishing surface and the polishing pad 16 is used.
The relationship with the submerged position of No. 8 can also be detected. Therefore, the pressing of the polishing surface adjusting ring 28 can be accurately adjusted.

Next, before explaining the operation of the wafer polishing apparatus 10, a pre-setting operation for setting the pressing force of the polishing surface adjusting ring 28 to an appropriate value will be described. First, the polishing surface adjusting ring 28 is brought into contact with the flat surface of the reference member, and the wafer 50 is pressed against the flat surface of the reference member via a pressure air layer. At this time, the position of the polishing surface adjustment ring 28 detected by the sensor 70 with respect to the carrier 24 is set to 0, and the polishing surface adjustment ring 2 for the carrier 24 is set.
8 is obtained.

Next, the polishing surface adjusting ring 28 is
Then, the polishing state of the wafer 50 when the wafer 50 is pressed with a predetermined pressing force is confirmed, and the sinking position of the polishing surface adjusting ring 28 with respect to the polishing pad 16 when the wafer 50 is uniformly polished is obtained. 4 to 6 show the polishing cloth 16 when the sinking position of the polishing surface adjusting ring 28 with respect to the polishing cloth 16 is changed.
FIG. 4 is an explanatory diagram showing a polishing pressure applied to a wafer 50 from FIG.

FIG. 4 shows the polishing pressure when the sinking position of the polishing surface adjusting ring 28 is substantially on the surface of the polishing pad 16, that is, when the pressing force is small. In this case, since the polishing surface adjusting ring 28 has a small force to press the polishing cloth 16, the polishing cloth 16 rises on the peripheral edge 50 </ b> A of the wafer 50, and the peripheral edge 50 </ b> A of the wafer 50 is polished more.

FIG. 5 shows the polishing pressure when the sinking position of the polishing surface adjusting ring 28 is at a position considerably deeper than the surface of the polishing pad 16, that is, when the pressing force is large.
In this case, since the pressing force of the polishing surface adjustment ring 28 against the polishing pad 16 is excessive, the polishing pad 16 does not contact the peripheral edge 50A of the wafer 50, and the peripheral edge 50A of the wafer 50
Will not be polished.

FIG. 6 shows the polishing surface adjusting ring 2 which makes the polishing pad 16 contact the peripheral edge 50A of the wafer 50 and does not cause the polishing pad 16 to bulge on the peripheral edge 50A of the wafer 50.
8 shows the sinking position. At the sinking position, the polishing pressure applied from the polishing pad 16 to the wafer 50 becomes uniform, and the entire surface of the wafer 50 is polished uniformly. The air pressure at this time is read from the regulator 38A, and this air pressure is stored in the RAM 75 of the CPU 74. At the time of polishing, the air pressure is read from the RAM 75, and the regulator 38A is controlled by the CPU 74 so as to maintain the air pressure. Thus, the previous setting operation is completed.

Next, the operation of the wafer polishing apparatus 10 configured as described above will be described. First, after raising the wafer holding head 14, the suction pump 46 is driven to suck and hold the wafer 50 to be polished on the porous plate 42. Next, the wafer holding head 14 is lowered, and the lowering movement is stopped at a position where the contact surface 29 of the polishing surface adjusting ring 28 of the wafer holding head 14 contacts the polishing pad 16. Then, the suction pump 46 is stopped to release the suction of the wafer 50, and the wafer 50 is removed from the polishing pad 1.
6. Place on top.

Next, the air pump 40 is driven to supply the compressed air to the air chamber 51 through the air supply path 48, and a pressure air layer is formed in the air chamber 51. And the air pump 4
Compressed air from the space 60 through the air supply passage 36.
Then, the central portion 30A of the rubber sheet 30 is elastically deformed by internal air pressure to press the carrier 24, and the wafer 50 is pressed against the polishing pad 16 via the pressure air layer. Then, the air pressure is adjusted by the regulator 38B to control the internal air pressure to a desired pressure, and the pressing force (polishing pressure) of the wafer 50 against the polishing pad 16 is kept constant.

Next, compressed air from the air pump 40 is supplied to the space 64 via the air supply path 34,
The outer peripheral portion 30 </ b> B is elastically deformed by the internal air pressure to press the polishing surface adjusting ring 28, and the lower surfaces of the polishing surface adjusting ring 28 and the retainer ring 62 are pressed against the polishing pad 16. Then, the air pressure is adjusted by the regulator 38A so that the air pressure stored in the RAM 75 of the CPU 74 becomes equal to that of the polishing pad 1.
6 is positioned at a position where the polishing pressure applied to the wafer 50 becomes uniform (see FIG. 6). And the regulator 38
A keeps the air pressure constant.

Then, the polishing pressure is set by the external input device 80 shown in FIG. 3, and thereafter, the polishing of the wafer 50 is started by rotating the polishing platen 12 and the wafer holding head 14. The setting of the polishing pressure by the external input device 80 may be set in advance, instead of immediately before the polishing. And the sensors 70, 72, 72, 72,
The CPU 74 calculates the polishing amount of the wafer 50 during polishing, and outputs a polishing end signal when the calculated polishing amount of the wafer 50 reaches a preset polishing target value. Stop. Thus, polishing of one wafer 50 is completed. When the second and subsequent wafers 50 are polished, the above-described steps may be repeated.

As described above, in this embodiment, the wafer 50 is polished by setting the sinking position of the polishing surface adjusting ring 28 to a position where the polishing pressure applied from the polishing pad 16 to the wafer 50 becomes uniform. The wafer 50
Can be uniformly polished. The optimum sinking position of the polishing surface adjusting ring 28 differs depending on the hardness of the polishing pad 16. That is, when the polishing cloth 16 is a hard polishing cloth 16 made of polyurethane, the polishing surface adjusting ring 28 is used.
Is made equal to the height position of the polished surface of the wafer 50. On the other hand, when the polishing pad 16 is a soft polishing pad made of polyurethane and sponge, the sinking position of the polishing surface adjusting ring 28 is set closer to the surface plate 12 than the height position of the polishing surface of the wafer 50. Position. That is,
The polishing surface adjustment ring 28 is pushed into the polishing cloth 16. When the hard polishing cloth 16 is compared with the soft polishing cloth 16, the soft polishing cloth 16 has a larger bulge amount at the wafer edge.

FIG. 7 shows a second example of the wafer holding head 14A.
FIG. 3 is a longitudinal sectional view showing the embodiment of FIG.
The same reference numerals are given to the same or similar members as those of the wafer holding head 14 according to the embodiment, and the description is omitted. The wafer holding head 14A shown in FIG. 7 has a capacity sensor 82 attached to the arm 76 of the polishing surface adjustment ring 28, and detects the relative displacement between the carrier 24 and the polishing surface adjustment ring 28 by the capacity sensor 82, whereby the polishing cloth 16 Of the polishing surface adjustment ring 28 with respect to. As described above, even when the capacitance sensor 82 shown in FIG. 7 is used in place of the sensor 70 (differential transformer) shown in FIG.

FIG. 8 shows a third example of the wafer holding head 14B.
FIG. 3 is a longitudinal sectional view showing the embodiment of FIG.
The same reference numerals are given to the same or similar members as those of the wafer holding head 14 according to the embodiment, and the description is omitted. In the wafer holding head 14B shown in FIG. 8, a small groove 78A is formed on the outer peripheral portion of the carrier 24, and this groove 78A is formed.
A differential transformer 84 is disposed at the second position to detect a relative displacement between the carrier 24 and the polishing surface adjustment ring 28. The differential transformer 84 has a short arm 76A projecting from the inner surface of the polishing surface adjusting ring 28.
A bobbin 86 is provided at the tip of the
Four sides are provided. As described above, even when the differential transformer 84 is provided on the outer peripheral portion of the carrier 24, the position where the polishing surface adjusting ring 28 sinks with respect to the polishing pad 16 can be detected.

FIG. 9 shows a fourth example of the wafer holding head 14C.
FIG. 3 is a longitudinal sectional view showing the embodiment of FIG.
The same reference numerals are given to the same or similar members as those of the wafer holding head 14 according to the embodiment, and the description is omitted. In the wafer holding head 14C shown in FIG. 9, a Hall sensor (magnetic sensor) 90 is attached to the arm 76 of the polishing surface adjusting ring 28, and a magnet 92 is attached to a surface of the Hall sensor 90 facing the carrier 24. And this wafer holding head 14C is
By detecting the relative displacement between the carrier 24 and the polishing surface adjusting ring 28 based on the Hall voltage output from the Hall sensor 90, the position of the polishing surface adjusting ring 28 sinking with respect to the polishing pad 16 is detected. Thus, instead of the sensor 70 (differential transformer) in FIG.
By using the Hall sensor 90 described above, the sinking position of the polishing surface adjusting ring 28 with respect to the polishing pad 16 can be detected.

In the first to fourth embodiments,
Although an example in which a differential transformer, a capacitance sensor, and a Hall sensor are applied as the position detecting means has been described, the present invention is not limited to this. For example, a non-contact sensor such as an eddy current sensor, an ultrasonic sensor, or a laser sensor (light wave interference device) may be applied, or a linear scale including a scale and a photo sensor may be applied. In this linear scale, the scale is provided on the polishing surface adjustment ring 28,
If a photo sensor for reading the scale is provided on the carrier 24, the sinking position of the polished surface adjustment ring 28 can be detected.

FIG. 10 is a plan view showing a fifth embodiment of the wafer holding head 114, and FIG. 11 is a longitudinal sectional view taken along line 11-11 of FIG. The wafer holding head 114 shown in FIG. 11 includes a head body 122, a carrier 124, a guide ring 126, and a polishing surface adjustment ring 12
8, a retainer ring 130, a rubber sheet 132, a differential transformer 134, a pressing member 136, and the like.

The head body 122 is formed in a disk shape, and has a rotating shaft 138 connected to the upper surface thereof, and is rotated in the direction of arrow B by a motor (not shown) connected to the rotating shaft 138. Further, air supply paths 140 and 144 are formed in the head main body 122. The air supply path 140 extends outside the wafer holding head 114 as shown by a two-dot chain line in FIG. 11, and is provided with an air pump (A) through a regulator (R) 146A.
P: air pump) 148. Similarly, an air supply path 144 is also provided outside the wafer holding head 114, and is provided through an air pump 14 via a regulator 146C.
8 is connected.

The carrier 124 is formed in a substantially columnar shape, and is arranged coaxially with the head main body 122 below the head main body 122. In addition, a concave portion 125 is formed on the lower surface of the carrier 124, and a porous plate 150 having air permeability is accommodated in the concave portion 125. In the porous plate 150, air passages 152, 152 formed in the carrier 124 are provided.
Are communicated with each other, and these air paths 152, 152 are
As shown by the two-dot chain line in FIG.
4 and extended outside the suction pump (SP: suctio
n pump) 176. Therefore, when the suction pump 176 is driven, the wafer 154 is sucked by the porous plate 150 and held by the porous plate 150. The porous plate 150 has a number of air passages inside, and for example, a porous plate made of a sintered body of a ceramic material is used.

On the lower surface of the carrier 124 and around the porous plate 150, a number of air supply passages 178, 178 are provided.
(Only two air supply paths are shown in FIG. 11). The air supply paths 178, 178,... Extend outside the carrier 124 and are connected to an air pump 148 via a regulator 146D. Therefore, when the air pump 148 is driven, the air pump 148
Are blown out into the space 156 between the carrier 124 and the wafer 154 via the air supply paths 178, 178,. Thus, a pressure air layer is formed in the space 156, and the pressing force of the carrier 124 is transmitted to the wafer 154 via the pressure air layer. Wafer 154
Is polished by being pressed against the polishing pad 116 by the pressing force transmitted through the pressure air layer.

On the other hand, the head body 122 and the carrier 124
A single rubber sheet 132 is disposed between the two. The rubber sheet 132 is formed in a disk shape with a uniform thickness. In addition, the rubber sheet 132 is provided with an annular stopper 1.
58 is fixed to the lower surface of the head main body 122. As a result, the rubber sheet 132 is divided into a central part 132A and an outer peripheral part 132B with the stopper 158 as a boundary. The central portion 132A of the rubber sheet 132 presses the carrier 124, and the outer peripheral portion 132B functions as an air bag for pressing the polishing surface adjustment ring 128.

In the air bag, the rubber sheet 13
The air supply path 140 is communicated with an airbag 162 defined by the central portion 132A of the second airbag. Therefore, when compressed air is supplied from the air supply path 140 to the airbag 162, the central portion 132A of the rubber sheet 132 is elastically deformed by air pressure and presses the upper surface of the carrier 124. Thereby, the wafer 154 with respect to the polishing cloth 116 is formed.
Pressing force can be obtained. Further, if the air pressure is adjusted by the regulator 146A, the pressing force (polishing pressure) of the wafer 154 can be controlled.

The guide ring 126 is formed in a cylindrical shape, and is disposed coaxially with the head main body 122 below the head main body 122. The guide ring 126 is fixed to the head main body 122 via a rubber sheet 132. Between the guide ring 126 and the carrier 124,
A polishing surface adjustment ring 128 is provided. Inside the polishing surface adjusting ring 128, a retainer ring 130 for preventing the wafer 154 from jumping out is attached to an outer peripheral portion of the carrier 124.

At the lower outer peripheral portion of the head main body 122,
An annular airbag 164 defined by the outer peripheral portion 132B of the rubber sheet 132 and the stopper 158 is formed. The air bag 164 is connected to the air supply path 144.
Is communicated. Therefore, when compressed air is supplied from the air supply path 144 to the air bag 164, the outer peripheral portion 132 </ b> B of the rubber sheet 132 is elastically deformed by air pressure and presses the annular upper surface 128 </ b> A of the polishing surface adjustment ring 128, and the polishing surface adjustment ring 128 is pressed. Is pressed against the polishing pad 116. The pressing force of the polishing surface adjusting ring 128 can be controlled by adjusting the air pressure with the regulator 146C.

By the way, a pressing member 136 is arranged between the carrier 124 and the polishing surface adjusting ring 128. The pressing member 136 includes the main body 136A, the support arm 1
36C and legs 136D. In addition,
Support arm 136C of pressing member 136 and leg 136
As shown by dotted lines in FIG. 10, three Ds are formed at equal intervals. The legs 136D are not limited to three, and may be formed in a cylindrical shape so as to cover the entire circumference of the carrier 124.

The main body 1 of the pressing member 136 shown in FIG.
36A is disposed in an opening 129 formed in the polishing surface adjustment ring 128. The leg 136D of the pressing member 136 is disposed in a through hole 128C formed in the polishing surface adjustment ring 128. Thereby, the leg 13
Since the surface of the polishing cloth 116 with which the lower surface 137 of the 6D abuts is leveled by the contact surface 128B of the polishing surface adjustment ring 128, the pressing member 136 is prevented from vibrating up and down due to the uneven surface of the polishing cloth 116. Have been.

The pressing member 136 is made of a low-thermal-expansion material (amber) having a very low coefficient of thermal expansion as a base material in order to prevent thermal expansion due to polishing processing heat. The lower surface 137 is
Diamond coated so that it is not polished. The lower surface 137 is not limited to the diamond coating, and may be formed of a material (for example, ceramic) having a significantly lower processing rate than the wafer 154.

On the other hand, the support arm 1 of the pressing member 136
A differential transformer 1 for detecting a submerged position of the polishing surface adjustment ring 128 with respect to the polishing cloth 116 is provided at the tip of the 36C.
34 are provided. The differential transformer 134 includes a core 170, a bobbin 172, and a contact 174. The bobbin 172 is connected to an arithmetic unit (not shown) that calculates the sinking position based on the relative vertical movement amount of the bobbin 172 and the core 170.

The bobbin 172 is fixed to the distal end of the support arm 136C of the pressing member 136.
2, the core 170 is disposed so as to be vertically movable relatively to the bobbin 172. A rod 176 is fixed below the core 170 coaxially with the core 170, and the contact 174 is fixed to a lower end of the rod 176. The contact 174 is in contact with the carrier 124.

Therefore, according to the differential transformer 134, by calculating the position of the bobbin 172 with respect to the core 170, the sinking position of the polishing surface adjusting ring 128 with respect to the polishing cloth 116 can be detected. Also,
As the wafer 154 is polished, the position of the carrier 124 with respect to the polishing cloth 116 varies, but the sinking position of the polishing surface adjustment ring 128, that is, the air pressure applied to the polishing surface adjustment ring 128, is initialized before polishing. Therefore, even if the position of the carrier 124 with respect to the polishing pad 116 fluctuates during polishing, the sinking position is kept constant.

In the example shown in FIG. 11, the sunk position is detected with reference to the carrier 124. Therefore, when the position of the carrier 124 with respect to the polishing pad 116 fluctuates, the sunk position is accurately detected. Although not possible, the position of the carrier 124 with respect to the polishing cloth 116 is
Since there is almost no change due to the air pressure of the pressure air layer in the space 156, there is no problem even if the sinking position is detected based on the carrier 124.

Next, the operation of the wafer holding head 114 configured as described above will be described. First, after raising the wafer holding head 114, the suction pump 1
76 to drive the wafer 154 to be polished to the porous plate 1
50 is held by suction. Next, the wafer holding head 11
4 is lowered, and the lowering movement of the wafer holding head 114 is stopped at a position where the contact surface of the polishing surface adjusting ring 128 of the wafer holding head 114 is in contact with the polishing pad 116.
Then, the suction pump 176 is stopped, and the wafer 1 is stopped.
Then, the suction of the wafer 54 is released, and the wafer 154 is placed on the polishing pad 116.

Then, the air pump 148 is driven to supply compressed air to the space 156 via the air supply passages 178, 178,.
To form a pressurized air layer in the space 156. At this time, the supply amount of compressed air is adjusted by controlling the regulator 146D, and the pressure P of the pressure air layer is set.
That is, the wafer 154 is polished with the rubber sheet 132 to the polishing cloth 11.
6 so that the pressure P (P> W) is greater than the pressure obtained by dividing the pressing force W pressing the wafer 6 on the wafer area A
/ A) is set. Thus, the pressure air layer is formed stably without being crushed by the carrier 124.

Next, the compressed air from the air pump 148 is supplied to the air bag 162 via the air supply path 140, and the central portion 132A of the rubber sheet 132 is elastically deformed by the internal air pressure to press the carrier 124. The wafer 154 is pressed against the polishing pad 116 via the pressure air layer. Then, the air pressure is adjusted by the regulator 146A to control the internal air pressure to a desired pressure.
Is kept constant.

At the same time, the air pump 148
Is supplied to the air bag 164 through the air supply path 144 and the outer peripheral portion 132 </ b> B of the rubber sheet 132.
Polished surface adjusting ring 1
28, the lower surfaces of the polishing surface adjustment ring 128 and the retainer ring 130 are pressed against the polishing pad 116. Then, the air pressure is adjusted by the regulator 146C, and the sinking position of the polishing surface adjustment ring 126 is positioned at a position where the polishing pressure applied from the polishing pad 116 to the wafer 154 becomes uniform. Then, the air pressure is kept constant by the regulator 146C.

Thereafter, the polishing platen 112 and the wafer holding head 114 are rotated to start polishing the wafer 154. Then, a polishing amount of the wafer 154 during polishing is calculated by the differential transformer 134, and when the calculated polishing amount of the wafer 154 reaches a preset polishing target value, a polishing end signal is output. Stop the polishing device. Thus, polishing of one wafer 154 is completed. When the second and subsequent wafers 154 are polished, the above-described steps may be repeated.

As described above, according to the wafer holding head 114 according to the fifth embodiment, since the pressing member 136 is arranged outside the retainer ring 130, the wafer 154 being polished is pressed onto the pressing member 136. There is no collision. Therefore, according to the wafer holding head 114,
Since the vibration of the pressing member 136 due to the wafer collision can be prevented, the polishing amount of the wafer can be more accurately detected.

The bobbin 172 of the differential transformer 134
The leg portion 136D of the pressing member 136 to which is attached is made of an invar having a very small coefficient of thermal expansion as a base material in order to prevent thermal expansion due to polishing processing heat.
Since the lower surface 137 pressed by 16 is coated with diamond so as not to be polished by the polishing cloth 16,
The bobbin 172 does not fluctuate from the reference position (zero position).
Thus, according to the differential transformer 134, the wafer polishing amount can be stably detected.

The lower surface 137 of the pressing member 136 is flattened by the polishing surface adjusting ring 128.
16, the pressing member 136 is attached to the polishing cloth 11.
6 does not vibrate vertically. Thus, according to the differential transformer 134, the polishing amount of the wafer 154 can be detected more accurately.

[0067]

As described above, according to the wafer polishing apparatus of the present invention, the sinking position of the polishing surface adjusting ring with respect to the polishing cloth is set at the position where the polishing pressure applied to the wafer from the polishing cloth becomes uniform. Since the wafer is polished by polishing, the concentration of the polishing pressure applied to the wafer from the polishing cloth can be prevented, and the entire surface of the wafer can be uniformly polished.

[Brief description of the drawings]

FIG. 1 is an overall structural diagram of a wafer polishing apparatus according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view showing a first embodiment of a wafer holding head applied to the wafer polishing apparatus of FIG. 1;

FIG. 3 is a block diagram showing a control system of the wafer polishing apparatus of FIG. 1;

FIG. 4 is a view for explaining a polishing pressure applied to a wafer from a polishing cloth when a pressing force of a polishing surface adjusting ring is small.

FIG. 5 is a diagram for explaining a polishing pressure applied to a wafer from a polishing cloth when a pressing force of a polishing surface adjustment ring is large.

FIG. 6 is a view for explaining a polishing pressure applied to a wafer from a polishing cloth when a pressing force of a polishing surface adjustment ring is set to an appropriate value.

FIG. 7 is a sectional view showing a second embodiment of the wafer holding head.

FIG. 8 is a longitudinal sectional view showing a third embodiment of the wafer holding head.

FIG. 9 is a cross-sectional view showing a fourth embodiment of the wafer holding head.

FIG. 10 is a plan view showing a fifth embodiment of the wafer holding head.

FIG. 11 is a longitudinal sectional view showing a fifth embodiment of the wafer holding head.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Wafer polishing apparatus 12, 112 ... Polishing surface plate 14, 14A, 14B, 14C, 114 ... Wafer holding head 16, 116 ... Polishing cloth 28, 128 ... Polishing surface adjustment ring 50, 154 ... Wafer 51 ... Air chamber 62, 130 ... retainer ring 70, 72 ... sensor 74 ... CPU 136 ... pressing member

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hisashi Terashita 9-7-1, Shimorenjaku, Mitaka-shi, Tokyo, Japan Tokyo Seimitsu Co., Ltd. (56) References JP-A-9-139366 (JP, A) 10-113862 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B24B 37/00 H01L 21/304 622

Claims (12)

(57) [Claims] 1. A wafer is pressed against a rotating polishing cloth,
In a wafer polishing apparatus for polishing a surface of a wafer, a carrier for holding the wafer and pressing the wafer against the polishing cloth, a polishing surface adjusting ring surrounding the wafer and pressed against the polishing cloth together with the wafer, a polishing surface adjustment Pressing means for pressing the ring against the polishing cloth ; and
Position detecting means for detecting by the relative position of the carrier and the polishing surface adjusting ring, the sinking position detected by the position detecting means, such that the polishing pressure applied to the wafer from the polishing cloth is located at a position where the polishing pressure is uniform. Control means for controlling the pressing force of the pressing means, comprising: 2. Pressing a wafer against a rotating polishing cloth,
In a wafer polishing apparatus for polishing a surface of a wafer, a carrier for holding the wafer, first pressing means for pressing the carrier toward the polishing cloth, and forming a pressure air layer between the carrier and the wafer A pressure air layer forming means for transmitting a pressing force from the first pressing means to the wafer via the pressure air layer; and a retainer ring provided outside the carrier for preventing the wafer from jumping out of the carrier. A polishing surface adjustment ring provided outside the retainer ring and brought into contact with the polishing cloth together with the wafer; a second pressing means for pressing the polishing surface adjustment ring against the polishing cloth; a polishing surface for the polishing cloth A position detecting means for detecting a submerged position of the adjusting ring; and a submerged position detected by the position detecting means. As the polishing pressure applied to Doha located at a position a uniform wafer polishing apparatus characterized by comprising a control means for controlling the pressing force of the second pressing means. 3. A wafer polishing apparatus for polishing a surface of a wafer by pressing the surface of the wafer against a rotating polishing cloth, comprising: a carrier for holding the wafer; and a first pressing for pressing the carrier toward the polishing cloth. Means, a pressure air layer forming means for supplying air between the carrier and the wafer to form a pressure air layer, and transmitting a pressing force from the first pressing means to the wafer via the pressure air layer; A retainer ring provided outside the carrier to prevent the wafer from jumping out of the carrier; a polishing surface adjustment ring provided outside the retainer ring and brought into contact with the polishing cloth together with the wafer; A second pressing means for pressing a surface adjustment ring against the polishing cloth; a second pressing means provided outside the retainer ring; A pressing member that is pressed against the polishing cloth and is brought into contact with the flattened polishing cloth; provided on the pressing member, detecting a relative displacement between the pressing member and the carrier, and based on the relative displacement. Position detecting means for detecting a sinking position of the polishing surface adjusting ring with respect to the polishing cloth; and so that the sinking position detected by the position detecting means is located at a position where the polishing pressure applied to the wafer from the polishing cloth becomes uniform. And control means for controlling the pressing force of the second pressing means. 4. The wafer polishing apparatus according to claim 1, wherein said position detecting means is a differential transformer having a core and a bobbin. 5. The wafer polishing apparatus according to claim 2, wherein said position detecting means is a differential transformer having a core and a bobbin. 6. The wafer polishing apparatus according to claim 3, wherein said position detecting means is a differential transformer having a core and a bobbin. 7. The wafer polishing apparatus according to claim 1, wherein said position detecting means is a capacitance sensor. 8. A wafer polishing apparatus according to claim 2, wherein said position detecting means is a capacitance sensor. 9. The wafer polishing apparatus according to claim 3, wherein said position detecting means is a capacitance sensor. 10. The pressing member is made of a low thermal expansion material, and a contact surface of the pressing member pressed against the polishing cloth is diamond-coated so as not to be polished by the polishing cloth, or is made of ceramic. 4. The wafer polishing apparatus according to claim 3, wherein: 11. The wafer polishing apparatus according to claim 2, wherein said retainer ring is made of a softer material than said polishing surface adjusting ring. 12. The wafer polishing apparatus according to claim 3, wherein said retainer ring is made of a softer material than said polishing surface adjusting ring.