JPH10193253A - Wafer polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily separate and retreat a wafer holding head not holding a wafer from a polishing pad by providing a pressure switching means to switch connection of a pressurizing means, a negative means and a fluid chamber. SOLUTION: In a wafer holding head 27 which does not hold a wafer W, its fluid chamber 36 is put in a condition of being connected not to a pressurizing means 37 but to a negative pressure means 38 by a pressure switching means C, and air of its fluid chamber 36 is sucked by the negative pressure means 38, and the fluid chamber 36 is put in a negative pressure condition, and a carrier 30 is separated and retreated from a polishing pad. At this time, a retainer ring 41 is also retreated by being put in a condition of separating from the polishing pad. That is, there is no need to use a dummy wafer, and the wafer holding head 27 which does not hold the wafer W is not polished by coming into contact with the polishing pad.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a wafer polishing apparatus for polishing a surface of a semiconductor wafer or the like forming an integrated circuit.

[0002]

2. Description of the Related Art As a wafer polishing apparatus of this kind, a disk-shaped platen having a polishing pad attached to a surface thereof and a plurality of wafer polishing apparatuses for holding one surface of a wafer to be polished and bringing the other surface of the wafer into contact with the polishing pad. It is widely known that a wafer holding head and a head driving mechanism for rotating these wafer holding heads relative to a platen are used, and polishing is performed by supplying a slurry containing abrasive grains between a polishing pad and a wafer. ing.

As a wafer polishing apparatus of this type, for example, US Pat. No. 5,205,082 discloses an apparatus employing a plurality of wafer holding heads as shown in FIG. This wafer holding head has a hollow head body 1.
And a diaphragm 2 stretched horizontally in the head body 1
And a carrier 4 fixed to the lower surface of the diaphragm 2, and into an air chamber 6 defined by the diaphragm 2,
By supplying pressurized air from a pressurized air source 10 through a shaft 8, the carrier 4 has a floating head structure capable of pressing the carrier 4 downward. Such a floating head structure has an advantage that the contact pressure of the wafer against the polishing pad can be made uniform.

A retainer ring 12 is arranged concentrically on the outer periphery of the carrier 4, and this retainer ring 12 is also fixed to the diaphragm 2. The lower end of the retainer ring 12 projects below the carrier 4, thereby holding the outer periphery of the wafer attached to the lower surface of the carrier 4. By holding the outer periphery of the wafer in this manner, a problem that the wafer being polished comes off the carrier 4 can be prevented.
Further, it is stated that overpolishing at the outer peripheral portion of the wafer can be prevented by surrounding the wafer with a retainer ring 12 and polishing the lower end of the retainer ring 12 at the same height as the lower surface of the wafer.

Conventionally, in the above wafer polishing apparatus, when the number of product wafers to be polished at a time is smaller than the number of wafer holding heads (for example, when there are six wafer holding heads, In the case of three wafers), polishing was performed by holding a dummy wafer on a wafer holding head that does not hold a product wafer. The reason for using the dummy wafer in this way is to prevent the wafer holding head from directly contacting the polishing pad and being polished.

[0006]

However, the above-mentioned wafer polishing apparatus has the following problems. In other words, when the number of product wafers to be polished is smaller than the number of wafer holding heads, dummy wafers that cannot be used as products must be prepared, and the work of attaching and detaching dummy wafers is required. Therefore, there is a disadvantage that the polishing operation is troublesome and the operation efficiency is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and does not require a dummy wafer even if the number of wafers to be polished is small, and prevents contact between a wafer holding head that does not hold a wafer and a polishing pad. It is an object of the present invention to provide a wafer polishing apparatus capable of performing the above.

[0008]

The present invention has the following features to attain the object mentioned above. That is, in the wafer polishing apparatus according to claim 1, a plurality of wafer holding heads for holding one surface of a wafer to be polished and holding the other surface of the wafer against the polishing pad, with a platen having a polishing pad attached to the surface. And a head drive mechanism for polishing the other surface of the wafer with the polishing pad by moving these wafer holding heads relative to the platen, wherein the wafer holding head is a disk for holding one surface of the wafer. -Shaped carrier, a head body which is formed in a cylindrical shape, is arranged substantially concentrically and internally, and supports the carrier on the inner peripheral surface, and is stretched between the carrier and the head body to connect them. And a fluid pressure filled in a fluid chamber formed between the diaphragm, the carrier and the head body. A pressure adjusting mechanism that is connected to the fluid chamber and pressurizes the fluid chamber; and a pressure adjusting mechanism that is connected to the fluid chamber and pressurizes the fluid chamber. Negative pressure means, and pressure switching means connected to the pressurizing means and the negative pressure means for switching the connection between these and the fluid chamber to selectively pressurize the fluid chamber to a pressurized state or a negative pressure state The technology having the following is adopted.

In this wafer polishing apparatus, the pressure adjusting mechanism has a pressurizing means for pressurizing the fluid chamber, a negative pressure means for setting the fluid chamber in a negative pressure state, and a pressure switch for switching connection between these and the fluid chamber. In the wafer holding head holding the wafer to be polished, the fluid chamber and the pressurizing means are connected by the pressure switching means, and the fluid chamber is pressurized by the pressurizing means. Is pressed against the polishing pad. In a wafer holding head which does not hold a wafer, the fluid chamber and the negative pressure means are connected by the pressure switching means, and the fluid chamber is negatively pressured by the negative pressure means to separate and retreat the carrier from the polishing pad. Let it.

According to a second aspect of the present invention, in the wafer polishing apparatus of the first aspect, a retainer ring is provided concentrically around the outer periphery of the carrier, and the retainer ring is fixed to the diaphragm and the head is fixed to the carrier. A technology is adopted which is capable of being displaced in the axial direction and is set so as to be separated from the polishing pad when the fluid chamber is brought into a negative pressure state by the negative pressure means.

In this wafer polishing apparatus, a retainer ring fixed to the diaphragm and capable of being displaced in the axial direction of the head is provided. Therefore, in a wafer holding head that does not hold a wafer, its fluid chamber is brought into a negative pressure state. The carrier is separated from the polishing pad, and the retainer ring connected to the carrier by the diaphragm is also separated from the polishing pad and retracted.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a wafer polishing apparatus according to the present invention will be described with reference to FIGS.

First, the overall structure will be briefly described with reference to FIG. 3. In the figure, reference numeral 21 denotes a base.
A disk-shaped platen 22 is horizontally installed at the center of the platen. The platen 22 is rotated about an axis by a platen drive mechanism provided in the base 21. A polishing pad 23 is attached to the entire upper surface of the platen.

Above the platen 22, a plurality of columns 24 are provided.
The upper mounting plate 25 is horizontally fixed via the. A disk-shaped carousel (head driving mechanism) 26 is fixed to the lower surface of the upper mounting plate 25, and a total of six wafer holding heads 27 facing the platen 22 are mounted on the carousel 26.
Is provided. These wafer holding heads 27
As shown in FIG. 4, at the same distance from the center of the carousel 26, the carousel 26 is arranged at every 60 ° around the central axis thereof, and is each planet-rotated by the carousel 26.
However, the number of wafer holding heads 27 is not limited to six, but may be two to five or seven or more.

Next, the wafer holding head 27 will be described with reference to FIGS. Wafer holding head 27
As shown in FIG. 1 and FIG. 2, a hollow head main body 28 which is arranged perpendicular to the axis and has an open lower end, a diaphragm 29 stretched inside the head main body 28, and fixed to the lower surface of the diaphragm 29 Disc shaped carrier 30
Is provided.

The head main body 28 includes a disc-shaped top plate 31,
A cylindrical peripheral wall portion 32 fixed to the outer periphery of the top plate portion 31
The top plate portion 31 is coaxially fixed to the shaft 33 of the carousel 26. On the inner peripheral surface of the peripheral wall portion 32, a mounting portion 34 of an annular step portion protruding radially inward over the entire circumference is formed, and the outer periphery of the disk-shaped diaphragm 29 is placed on the mounting portion 34. And is fixed by a fixing ring 35A. The diaphragm 29 is formed of an elastic material such as various rubbers.

On the other hand, a flow path 33a is formed in the shaft 33, and a fluid chamber 36 formed by the head body 28 and the diaphragm 29 is connected to a pressure switching means C such as a three-way valve through the flow path 33a. The pressure switching means C is
Further, a pressurizing means 3 which is a pressurized air source such as a compressor.
7 and negative pressure means 38 such as a vacuum pump, and the connection between these and the fluid chamber 36 can be selectively and appropriately switched for each wafer holding head 27.

The pressurizing means 37 or the negative pressure means 38
By adjusting the fluid pressure in the fluid chamber 36, the diaphragm 29 is vertically displaced, and the pressing pressure of the carrier 30 against the polishing pad 23 and the vertical position are changed. That is, the pressurizing means 37, the negative pressure means 38 and the pressure switching means C
Functions as a pressure adjusting mechanism of the fluid chamber 36. In addition,
As the fluid, it is generally sufficient to use air,
If necessary, another kind of gas or liquid may be used.

The carrier 30 is made of a material having high rigidity such as ceramic and has a constant thickness, and does not undergo elastic deformation. The carrier 30 is fixed with a plurality of bolts to a fixing ring 35B coaxially arranged on the upper surface of the diaphragm 29. An outwardly extending flange portion is formed at the upper end of the fixing ring 35B, and when the head is raised, the flange portion is held by a holding member 42 attached to the head main body 28 to support the weight of the carrier. .

On the outer periphery of the carrier 30, a retainer ring 41 is provided concentrically. The retainer ring 41 has a flat annular shape at the lower end surface, is arranged concentrically with a slight clearance between the retainer ring 41 and the outer peripheral surface of the carrier 30, and is vertically displaceable independently of the carrier 30. . Also, on the outer peripheral edge of the upper end of the retainer ring 41,
A holding portion 41A protruding radially outward is formed. When the wafer holding head 27 is pulled up from the platen 22 together with the carousel 26, the holding portion 41A is formed.
Is held by an annular stopper portion 43 at the lower end of the peripheral wall portion 32.

The stopper portion 43 protrudes radially inward from the lower peripheral edge of the peripheral wall portion 32 and is formed so as to abut on the outer periphery of the retainer ring 41 or surround the retainer ring 41 with a slight clearance.

The top plate section 31 is provided with a supply port 50 connected to a cleaning water supply means (not shown) provided outside, and a cleaning water supply hole 51 connected to the supply port 50. Formed inside. The downstream end opening of the washing water supply hole 51 is connected to the upstream end opening of the washing water circulation hole 52 formed in the peripheral wall 32, and the downstream end opening of the washing water circulation hole 52 is connected to the peripheral wall 32. Are formed on the inner peripheral surface and open toward the outer peripheral surface of the retainer ring 41. The retainer ring 41 is provided with a cleaning through-hole 53 which is disposed so as to penetrate from the outer peripheral surface to the inner peripheral surface of the retainer ring 41 so as to face the downstream end opening of the cleaning water flow hole 52.

That is, when cleaning water such as pure water is supplied from the cleaning water supply means to the supply port 50, the cleaning water flows through the cleaning water flow hole 52 through the cleaning water supply hole 51, and the cleaning water flow hole 52. Is supplied to the outer peripheral surface of the retainer ring 41 from the downstream end opening. Further, the cleaning water supplied to the outer peripheral surface of the retainer ring 41 flows through the cleaning through hole 53 and is supplied to the inner peripheral surface of the retainer ring 41. Therefore,
The cleaning water is supplied to the inner and outer peripheral surfaces of the retainer ring 41 by the above-described path, and the retainer ring 41 and the carrier 30
The slurry adhering to the can be washed away.

When polishing is performed, the wafer W is suction-fixed by suction holes (not shown) formed on the lower surface of the carrier 30 by being connected to suction means (not shown) such as a vacuum pump.

Next, the setting of the state of the wafer holding head 27 during polishing will be described separately for a case where the wafer W is held and a case where the wafer W is not held.

[When the Wafer W is Held] In the wafer holding head 27 which holds the wafer W to be polished, as shown in FIG. Pressing means 3
7, pressurized air is supplied to the fluid chamber 36 to make the fluid chamber 36 pressurized, and the wafer W attached to the carrier 30 is pressed against the polishing pad 23. At this time, the retainer ring 41 connected to the carrier 30 by the diaphragm 29 is similarly pressed by the polishing pad 23.

[When not holding wafer W] In the wafer holding head 27 not holding the wafer W,
As shown in FIG. 2, the fluid chamber 36 and the negative pressure means 38 are connected by the pressure switching means C, and the air in the fluid chamber 36 is sucked by the negative pressure means 38 to bring the fluid chamber 36 into the negative pressure state. , The carrier 30 is separated from the polishing pad 23.
Evacuate. At this time, the retainer ring 41 is also separated from the polishing pad 23 and is retracted.

Therefore, in the above-structured wafer polishing apparatus, the wafer holding head 2 holding the wafer W
The fluid pressure of the fluid chamber 36 can be set individually and selectively in a pressurized state, and the fluid chamber 36 of the wafer holding head 27 not holding the wafer W can be set in a negative pressure state. In other words, there is no need to use a dummy wafer,
The wafer holding head 27 that does not hold the wafer W abuts on the polishing pad 23 and is not polished.

Next, a second embodiment of the wafer polishing apparatus according to the present invention will be described with reference to FIGS.

The difference between the second embodiment and the first embodiment is that the wafer holding head 27 in the first embodiment has one diaphragm 29, whereas the wafer holding head 100 in the second embodiment has one diaphragm 29. The diaphragm includes a first diaphragm 101A and a second diaphragm 101.
B is divided into two parts.

Hereinafter, the wafer holding head 100 will be described in detail. The wafer holding head 100 has a hollow head body 102 which is arranged perpendicular to the axis and has an open lower end.
And a first diaphragm 101A and a second diaphragm 101B stretched inside the head main body 102.
And a disc-shaped carrier 103 fixed to the lower surface of the first diaphragm 101A. A retainer ring 104 is provided concentrically on the outer periphery of the carrier 103.

As in the first embodiment, the head body 102 includes a disk-shaped top plate 102A and a cylindrical peripheral wall 102B fixed to the outer periphery of the top plate 102A. The portion 102A is coaxially fixed to the carousel shaft 105. Further, on the inner peripheral surface of the peripheral wall portion 102B, a mounting portion 107 of an annular step portion that protrudes radially inward over the entire circumference is formed.

The retainer ring 104 has a flat annular lower end surface, and is concentrically arranged with a slight clearance between the retainer ring 104 and the outer peripheral surface of the carrier 103.
Up and down independently.

As in the first embodiment, a holding portion 108 projecting outward in the radial direction is formed on the outer peripheral edge of the upper end of the retainer ring 104.
When 00 is pulled up from the platen 22 together with the carousel 26, the holding portion 108 is held by the annular stopper portion 109 at the lower end of the peripheral wall portion 102B. The stopper portion 109 protrudes radially inward from the lower peripheral edge of the peripheral wall portion 102B, and
4 is formed so as to surround the retainer ring 104 with an abutment state or a small clearance on the outer periphery of the retainer ring 104.

On the upper surface of the carrier 103, the inner edge of the first diaphragm 101A is arranged on the same axis, and on the upper surface of the retainer ring 104, the outer edge of the first diaphragm 101A is arranged. I have. On the upper surface of the inner edge of the first diaphragm 101A, a first fixing ring 110 is arranged along the same axis, and the first fixing ring 110 is used to connect the first fixing ring 110 and the first diaphragm 101A. The first diaphragm 101A is fixed to the carrier 103 in a state where the first diaphragm 101A is sandwiched by a plurality of bolts 111 penetrating therethrough.

On the upper surface of the outer edge of the first diaphragm 101A, a connecting ring 112 is disposed along the same axis, and on the upper surface of the connecting ring 112, the inner edge of the second diaphragm 101B is disposed. Have been. And the second
On the upper surface of the inner edge of the diaphragm 101B, a second fixing ring 113 is arranged along the same axis, and the second fixing ring 113 is composed of a first diaphragm 101A, a connecting ring 112, and a second diaphragm 101B. And the second
The first diaphragm 101A and the second diaphragm 101B are fixed to the retainer ring 104 with the first diaphragm 101A and the second diaphragm 101B being sandwiched by a plurality of bolts 114 penetrating the fixing ring 113.

Further, the outer edge of the second diaphragm 101B is placed on the mounting portion 107, and on the upper surface of the outer edge,
A third fixing ring 115 is arranged coaxially. The third fixing ring 115 is fixed to the second diaphragm 101B by a plurality of bolts 116 penetrating the second diaphragm 101B and the third fixing ring 115.
Are fixed to the mounting portion 107 in a state where they are sandwiched. The first diaphragm 101A and the second diaphragm 101B are each formed of an elastic material such as various rubbers.

The flexible portion of the second diaphragm 101B, that is, the portion between the portion held by the mounting portion 107 and the portion held by the connecting ring 112 is the flexible portion of the first diaphragm 101A, ie, the retainer ring. The width is set wider than the portion between the holding portion 104 and the holding portion by the carrier 103. Therefore,
The second diaphragm 101B is the first diaphragm 1
It can bend more greatly in the vertical direction (axial direction) than 01A, and the flexibility in this direction is high.

On the other hand, a flow path is formed in the shaft 105, and a fluid chamber 117 formed by the head main body 102, the carrier 103, the first diaphragm 101A and the second diaphragm 101B passes through the flow path as in the first embodiment. Similarly, it is connected to a pressure switching means C such as a three-way valve. The pressure switching means C is further connected to a pressurizing means 37, which is a pressurized air source such as a compressor, and a negative pressure means 38, such as a vacuum pump, and connects these to the fluid chamber 117 for each wafer holding head 100. Can be selectively switched as needed.

The pressurizing means 37 or the negative pressure means 38
By adjusting the fluid pressure in the fluid chamber 117 with the first diaphragm 101A and the second diaphragm 1A,
01B is displaced up and down and the carrier 1 is transferred to the polishing pad 23.
The pressing pressure and the vertical position of 03 change. Reference numeral 120 denotes a second position at a predetermined position when the carrier 103 is retracted upward by the negative pressure means 38, as shown in FIG.
Of the top plate 102 so as to contact the upper surface of the fixing ring 113 of the
A retracting stopper attached to the lower surface of A.

In the wafer polishing apparatus according to the second embodiment having the above configuration, the carrier 103 is
The carrier 103 is pressed downward by adjusting the fluid pressure applied to the fluid chamber 117 by being attached to the first diaphragm 101A and the second diaphragm 101B, which are stretched through the connecting ring 112 to the carrier 2, so that the polishing is performed. The polishing process is performed by making the contact pressure of the wafer against the pad 23 uniform.

That is, a first diaphragm 101A that is stretched between the carrier 103 and the retainer ring 104 and connects them, and a second diaphragm 101B that is stretched between the retainer ring 104 and the head body 102 and connects them. Since the diaphragm is divided into two, the ability to follow the movement of the carrier 103 is improved and the contact pressure of the wafer is more uniform than in the case where the diaphragm is one. You.

Further, since the inner edge of the second diaphragm 101B is arranged and stretched above the outer edge of the first diaphragm 101A, the outer edge of the first diaphragm 101A and the inner edge of the second diaphragm 101B are stretched. Are overlapped in the axial direction, the second diaphragm 1
The outer diameter of the entire wafer holding head 100 can be reduced as compared with the case where the first wafer 101B is arranged on the same plane on the radially outer side of the first diaphragm 101A.

Note that the present invention includes the following embodiments. (1) Although the suction by the suction holes is used as the means for holding the wafer on the lower surface of the carrier, other holding means may be employed. For example, a wafer may be attached to the lower surface of the carrier via a wafer attachment sheet. The wafer-attached sheet is formed of a water-absorbing material such as a nonwoven fabric, and absorbs the wafer by surface tension when absorbing water. Further, the wafer may be attached to the lower surface of the carrier via wax.

(2) Although the first diaphragm 101A and the second diaphragm 101B in the wafer polishing apparatus of the second embodiment are set to the same thickness, they may be set to different thicknesses. For example, by setting the thickness of the first diaphragm to be thicker than that of the second diaphragm, the rigidity of the first diaphragm is increased. Therefore, the first diaphragm that directly receives the movement of the carrier is provided around the entire periphery of the carrier. It can be mounted with high uniformity and high accuracy over the entire surface, and the polishing accuracy is further improved. In addition, since the rigidity of the first diaphragm is high, the followability to the fine movement of the carrier is improved, and the flexibility of the thin second diaphragm is high, so that it can sufficiently cope with the large movement of the carrier and the retainer ring. is there.

(3) Although the first diaphragm 101A and the second diaphragm 101B in the wafer polishing apparatus of the second embodiment are formed of the same elastic material, they may be formed of different materials. For example, the first diaphragm is made of a tetrafluoroethylene resin-based material (for example,
The second diaphragm may be made of Teflon (registered trademark of DuPont), and the second diaphragm may be formed by coating a polyester thin film with rubber.

In this case, since the first diaphragm is formed of a tetrafluoroethylene resin material having high processing accuracy, high dimensional accuracy and mounting accuracy can be obtained over the entire circumference of the first diaphragm. Uniform rigidity is obtained. Further, since the second diaphragm has a structure in which rubber is coated on the polyester thin film, the second diaphragm has flexibility in the axial direction and high strength in the plane direction and high airtightness can be obtained.

Therefore, by adopting the second diaphragm, it has excellent followability to the movement of the carrier in the axial direction, and reliably prevents the working fluid acting on the second diaphragm from leaking. Further, the rotational force from the head body is favorably transmitted to the retainer ring and the carrier via the second diaphragm.

(4) Although the diaphragm of the first embodiment and the first diaphragm of the second embodiment are formed in an annular shape, they may be formed in a circular shape.

(5) In each of the above embodiments, suction by the suction holes is used as means for holding the wafer W on the lower surface of the carrier, but other holding means may be employed.
For example, a wafer may be attached to the lower surface of the carrier via a wafer attachment sheet. This wafer-attached sheet is formed of a material having water absorption such as a nonwoven fabric,
When water is absorbed, the wafer is absorbed by the surface tension. Further, the wafer may be attached to the lower surface of the carrier via wax.

[0051]

According to the present invention, the following effects can be obtained. (1) According to the wafer polishing apparatus of the first aspect, the pressure adjusting mechanism pressurizes the fluid chamber in the pressurized state, the negative pressure means sets the fluid chamber in the negative pressure state, and these and the fluid chamber. And pressure switching means for switching the connection between the wafers, so that the fluid chamber of each wafer holding head can be selectively set to a pressurized or negative pressure state depending on whether or not the wafer is held, and the carrier can be polished. It can be individually brought into contact with or separated from the pad. Therefore, the wafer holding head that does not hold a wafer can be easily separated and retracted from the polishing pad, and even if the number of wafers to be polished is small, there is no need to use a dummy wafer. Can be improved.

(2) According to the wafer polishing apparatus of the second aspect, since the retainer ring fixed to the diaphragm and capable of being displaced in the axial direction of the head is provided, the retainer ring as well as the carrier is selective with respect to the polishing pad. Can be brought into contact with or separated from. That is, in the wafer holding head holding the wafer, the retainer ring can hold the outer periphery of the wafer during polishing, and in the wafer holding head not holding the wafer, the retainer ring is retracted from the polishing pad. Can be done.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a wafer holding head holding a wafer in a first embodiment of a wafer polishing apparatus according to the present invention.

FIG. 2 is a sectional view showing a wafer holding head that does not hold a wafer in the first embodiment of the wafer polishing apparatus according to the present invention.

FIG. 3 is a front view showing the entire configuration of the wafer polishing apparatus according to the present invention.

FIG. 4 is a plan view showing an arrangement state of a wafer holding head and a platen of the apparatus.

FIG. 5 is a cross-sectional view showing a wafer holding head holding a wafer in a second embodiment of the wafer polishing apparatus according to the present invention.

FIG. 6 is a sectional view showing a wafer holding head that does not hold a wafer in a second embodiment of the wafer polishing apparatus according to the present invention.

FIG. 7 is a sectional view showing a wafer holding head in a conventional example of a wafer polishing apparatus according to the present invention.

[Explanation of symbols]

 22 Platen 23 Polishing Pad 26 Carousel (Head Driving Mechanism) 27,100 Wafer Holding Head 28,102 Head Main Body 29 Diaphragm 30,103 Carrier 31,102A Top Plate 32,102B Peripheral Wall 36,117 Fluid Chamber 37 Pressurizing Means 38 Negative pressure means 41, 104 Retaining ring 101A First diaphragm 101B Second diaphragm C Pressure switching means W Wafer

Claims (2)

[Claims] 1. A platen having a polishing pad attached to a surface thereof, a plurality of wafer holding heads for holding one surface of a wafer to be polished and abutting the other surface of the wafer to the polishing pad, A head drive mechanism for polishing the other surface of the wafer with the polishing pad by making relative movement with respect to the platen, wherein the wafer holding head has a disc-shaped carrier for holding one surface of the wafer, and a cylindrical shape. A head body which is formed on the carrier and which is arranged substantially concentrically and inside and supports the carrier on the inner peripheral surface; a diaphragm stretched between the carrier and the head body to connect them; and a diaphragm; A pressure adjusting mechanism for adjusting a fluid pressure filled in a fluid chamber formed between the carrier and the head main body, A force adjusting mechanism connected to the fluid chamber and configured to pressurize the fluid chamber; a pressure unit connected to the fluid chamber and configured to cause the fluid chamber to be in a negative pressure state; Pressure switching means connected to the negative pressure means for switching the connection between the negative pressure means and the fluid chamber to selectively set the pressure of the fluid chamber to a pressurized state or a negative pressure state. Wafer polishing equipment. 2. The wafer polishing apparatus according to claim 1, further comprising: a retainer ring disposed concentrically around an outer periphery of the carrier, wherein the retainer ring is fixed to the diaphragm and is displaceable in a head axis direction. The wafer polishing apparatus is set so as to be separated from the polishing pad when the fluid chamber is in a negative pressure state by the negative pressure means.