JP2000263401A - Wafer polishing device and wafer manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing device and a wafer manufacturing method for stably detecting a complicated state of the polishing work to a wafer. SOLUTION: A wafer holding head 1 is provided with a carrier 6 fixed to a diaphragm 5 spread within a head main body 2 so as to hold one surface of a wafer W to be polished, a plurality of torque transmitting mechanisms 20 provided along the circumferential direction between the carrier 6 and the head main body 2 and each having a sensor part 21, and an operation part 31 for operating the output from individual sensor part 21 so as to detect the force acting on the wafer W. The diaphragm 5 is so formed as not to be affected by excessive torque from the torque transmitting mechanism 20, while the force acting on the wafer W is directly observed by the sensor part 21 via the carrier 6. Therefore, the polishing work to the wafer W is carried out stably, with the force acting on the wafer W being detected.

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 a wafer manufacturing method used in an apparatus for polishing a semiconductor wafer surface in a semiconductor manufacturing process.

[0002]

2. Description of the Related Art In recent years, patterns have been miniaturized in accordance with high integration of a semiconductor manufacturing apparatus. In particular, since a fine pattern having a multilayer structure can be easily and reliably formed, a semiconductor wafer during a manufacturing process is required. It has become important to make the surface as flat as possible. In that case, a chemical mechanical polishing method (CMP method), which has a high degree of planarization, has been spotlighted for polishing a surface film.

In the CMP method, the wafer surface is chemically and mechanically polished using an alkaline solution using SiO 2, a neutral solution using SeO 2, an acidic solution using Al 2 O 3, an abrasive, etc. As a method for planarizing, there is a wafer polishing apparatus used in this method, for example, as shown in FIG.

FIG. 11 shows a wafer polishing apparatus 100.
Is provided with a wafer holding head 101 holding a wafer W to be polished, and a polishing pad 102 affixed over the entire surface of a platen 103 formed in a disk shape. Of these, a plurality of wafer holding heads 101 are mounted below the carousel 104, which is a head driving mechanism, are rotatably supported by a spindle 111, and are made to rotate planetarily on the polishing pad 102. In this case, the center position of the platen 103 and the revolving center of the wafer holding head 101 can be installed eccentrically.

[0005] The platen 103 is horizontally disposed at the center of the base 105, and is rotated around an axis by a platen driving mechanism provided in the base 105. A column 107 is provided on the side of the base 105, and an upper mounting plate 109 for supporting the carousel driving mechanism 110 is arranged between the columns 107. The carousel drive mechanism 110 has a function of rotating the carousel 104 provided below around an axis.

From the base 105, a butt 112 is arranged to protrude upward.
An interval adjusting mechanism 113 is provided at the upper end of the reference numeral 12. On the other hand, above the butting portion 112, the locking portion 11
4 are opposed to each other. The locking portion 114 is configured to be fixed to the upper mounting plate 109 and protrude downward from the upper mounting plate 109. Then, the distance adjusting mechanism 113 is adjusted so that the butting portion 112 and the locking portion 114 are brought into contact with each other, so that the distance between the wafer holding head 101 and the polishing pad 102 is made appropriate. Then, the wafer W held by the wafer holding head 101 is brought into contact with the surface of the polishing pad 102, and the wafer W is polished by rotating the carousel 104 and the platen 103.

When polishing is performed using such a wafer polishing apparatus 100, it is determined whether the polished surface of the wafer W has reached a desired state (polishing end point detection), for example, by determining the rotational power of the platen driving mechanism 106. This was done by observing the fluctuations. That is, when the polishing of the wafer W is insufficient, the frictional force generated between the polishing pad 102 and the wafer W becomes unstable and fluctuates. On the other hand, when the wafer W is polished to a desired polishing surface, Thus, the frictional force becomes stable. At this time, since the platen 102 is configured to be rotated at a constant speed, for example, when the polishing resistance is large, the rotational power of the platen driving mechanism 106 is large, while when the polishing resistance is small, the rotational power is small. Become. Then, the fluctuation of the rotational power of the platen driving mechanism 106 is observed, and when this observation value is stabilized, it is determined that the polished surface of the wafer W has reached a desired state.

[0008]

However, the method of observing the fluctuation of the rotational power of the platen driving mechanism 106 as the polishing end point detection is based on the detection of the polishing end point for each of the plurality of installed wafer holding heads 101. However, some wafers W were over-polished or under-polished, or over-polished products and under-polished products were mixed.

In many cases, the platen 102 is idle even when the wafer W and the polishing pad 102 are not in contact with each other. In this case, for example, when the wafer W is originally made of a material having a low polishing resistance, Since the rotational power fluctuation of the platen drive mechanism 106 during the polishing state of W and the completion state of W is small, it is mixed with the idling power component of the platen 102, and it is difficult to detect the polishing end point of the wafer W.

On the other hand, as a method of detecting the polishing end point, a method of detecting the rotational power of each wafer holding head 101 is conceivable. However, the response is poor, and the force acting on the wafer W cannot be accurately detected. Further, the force detected at this time includes, in addition to the frictional force acting on the wafer W, the frictional force acting on the portion of the wafer holding head 101 other than holding the wafer W and the contact portion with the polishing pad 102. In addition, accurate polishing end point detection could not be performed.

The present invention has been made in view of such circumstances, and provides a wafer polishing apparatus capable of stably detecting a polishing state of a wafer and a state in which polishing has been completed, and a method of manufacturing the same. The purpose is.

[0012]

According to a first aspect of the present invention, there is provided a platen having a polishing pad affixed to a surface thereof, and a wafer to be polished held on the polishing pad. A wafer polishing apparatus for polishing the wafer with the polishing pad by rotating the wafer holding head and the platen, respectively, comprising:
The wafer holding head, a head body comprising a top plate portion and a cylindrical peripheral wall portion provided below the outer periphery of the top plate portion,
A diaphragm extending perpendicularly to a head axis in the head main body, a pressure adjusting mechanism for adjusting a fluid pressure filled in a fluid chamber formed between the diaphragm and the head main body, and fixed to the diaphragm It is provided so as to be displaceable in the head axis direction together with the diaphragm, and a carrier for holding one surface of a wafer to be polished, and concentrically arranged between the inner wall of the peripheral wall portion and the outer periphery of the carrier, A plurality of retainer rings which are fixed to the diaphragm and are displaceable in the head axis direction together with the diaphragm, and which are in contact with a polishing pad during polishing; and a plurality of retainer rings are provided along the circumferential direction between the head body and the carrier. A torque transmission mechanism for transmitting a torque of a main body to the carrier, and the respective torque transmissions; A plurality of sensor units for observing a rotational force acting on the wafer, and connected to the respective sensor units, and calculating a force acting on the wafer based on outputs from these sensor units. And a calculation unit that performs the calculation.

According to the present invention, by providing the torque transmitting mechanism on the upper surface of the carrier, even in the configuration having the diaphragm which is an elastic body, the torque of the head main body can be accurately transmitted to the carrier, and the diaphragm can be moved. Since the excessive rotational force is not applied, the diaphragm is prevented from deteriorating. In addition, since the sensor portion is provided in the torque transmission mechanism, the force acting on the wafer is directly observed on the sensor portion via the carrier, so that, for example, a portion other than holding the wafer of the wafer holding head such as a retainer ring. Is accurately detected even in the state in which it comes into contact with the polishing pad. Then, the calculation unit calculates the force acting on the wafer based on the outputs from the plurality of sensor units.

According to a second aspect of the present invention, there is provided the wafer polishing apparatus according to the first aspect, wherein the torque transmitting mechanism comprises:
A first formed so as to extend downward from the lower surface of the top plate portion
A member and a second member provided on the upper surface of the carrier, the second member being in contact with a part of the first member in the rotation direction of the wafer holding head during polishing and being displaceable in the axial direction with respect to the first member. And the sensor unit comprises:
A wafer polishing apparatus is provided at a contact portion between the first member and the second member.

According to the present invention, since the sensor section is provided at the contact portion between the first member and the second member, even when the wafer holding head is in a rotating state, the force acting on the wafer is reliably detected. You. Furthermore, since the second member is provided so as to be displaceable with respect to the first member, the displacement of the carrier and the retainer ring supported by the diaphragm in the axial direction is not hindered, and the polishing of the wafer is stable. It is done.

According to a third aspect of the present invention, there is provided a platen having a polishing pad attached to a surface thereof, and a wafer holding head for holding a wafer to be polished and bringing one surface of the wafer into contact with the polishing pad, A wafer manufacturing method including a polishing step of polishing the wafer with the polishing pad by rotating the wafer holding head and the platen, respectively, wherein the wafer holding head includes a top plate portion and the top plate portion. A head body comprising a cylindrical peripheral wall provided below the outer periphery of the head, a diaphragm stretched in the head body perpendicular to the head axis, and a fluid formed between the diaphragm and the head body. A pressure adjusting mechanism for adjusting a fluid pressure filled in the chamber; and a head fixed to the diaphragm and capable of being displaced in the head axis direction together with the diaphragm. A carrier for holding one surface of a wafer to be polished, and a concentrically arranged between an inner wall of the peripheral wall portion and an outer periphery of the carrier, and fixed to the diaphragm and a head axis together with the diaphragm. Are provided so as to be displaceable in the direction, a plurality of retainer rings that come into contact with the polishing pad during polishing, and a plurality of retainer rings are provided along the circumferential direction between the head body and the carrier,
A torque transmission mechanism for transmitting the torque of the head body to the carrier, a plurality of sensor units provided on the respective torque transmission mechanisms, for observing a force in a rotational direction acting on the wafer, And a computing unit that calculates a force acting on the wafer based on outputs from these sensor units,
The wafer held by the wafer holding head is rotated while being in contact with the polishing pad, and the force acting on the wafer is calculated by the calculation unit based on the output from the respective sensor units. And polishing the wafer while determining the polishing state of the wafer based on the output of the wafer.

According to the present invention, the force acting on the wafer is directly observed by the sensor provided on the upper surface of the carrier, and the polishing state of the wafer is determined based on the output from the sensor. Therefore, occurrence of wafers such as overpolishing or insufficient polishing is reduced, and stable wafer polishing is realized.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A wafer polishing apparatus and a wafer manufacturing method according to one embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a wafer holding head 1 in one embodiment of the wafer polishing apparatus of the present invention.
The wafer holding head 1 is installed in, for example, the carousel 104 shown in FIG.

In FIG. 1, a wafer holding head 1 is
A head body 2 including a top plate 3 and a peripheral wall 4 formed in a cylindrical shape; a diaphragm 5 formed of an elastic body stretched inside the head body 2; and a disk-shaped carrier fixed to the lower surface of the diaphragm 5 6, the inner wall of the peripheral wall portion 4 and the carrier 6
And an annular retainer ring 7 provided concentrically on the outer peripheral surface of the ring. The carrier 6 and the retainer ring 7 have a floating structure that can be moved in the axial direction by elastic deformation of the diaphragm 5.

The head body 2 is composed of a disk-shaped top plate 3 and a cylindrical peripheral wall 4 fixed below the outer periphery of the top plate 3, and the lower end of the head body 2 is open and hollow. It has become. The top plate 3 is coaxially fixed to a shaft portion 9 which is a connecting portion for connecting to the carousel, and a flow path 15 is formed in the shaft portion 9 in a vertical direction. An external thread 8 is formed on the outer peripheral surface of the shaft 9. A step portion 4a and an annular locking portion 10 projecting inward in the radial direction are provided on the lower portion of the peripheral wall portion 4 over the entire circumference.
Are formed.

The diaphragm 5 made of an elastic material such as fiber reinforced rubber is formed in an annular shape or a disk shape, and is fixed on a step 4 a formed on the inner wall of the peripheral wall 4 by a diaphragm fixing ring 11. .

A fluid chamber 14 is formed above the diaphragm 5 and communicates with a flow path 15 formed in the shaft 9. The pressure inside the fluid chamber 14 is adjusted by supplying a fluid such as air into the fluid chamber 14 from the pressure adjusting mechanism 30 through the flow path 15.

The carrier 6 made of a high-rigidity material such as ceramic is formed in a substantially disk-like shape with a constant thickness, and a carrier fixing ring 12 provided on the upper surface of the diaphragm 5.
Has been fixed by. An annular step portion 12 a is formed in an upper portion of the carrier fixing ring 12, and the top plate portion 3 is formed.
Nut 19 and spacer 19 inserted vertically from
The stopper bolt 18 is engaged with a step 18a formed at the lower end of the stopper bolt 18 fixed by a. Then, even if the wafer holding head 1 is raised by, for example, the elevating mechanism 118 and the diaphragm 5 bends downward due to the weight of the carrier 6 or the like, the excessive engagement of the diaphragm 5 is caused by the engagement of the step 12a and the step 18a. No force is applied.

The retainer ring 7 is formed in an annular shape between the inner wall of the peripheral wall 4 and the outer peripheral surface of the carrier 6, and slightly between the inner wall of the peripheral wall 4 and the outer peripheral surface of the carrier 6. It is arranged concentrically with the peripheral wall portion 4 and the carrier 6 with an appropriate gap. The retainer ring 7 has an upper end surface and a lower end surface formed horizontally, and is fixed by a retainer ring fixing ring 13 provided on the upper surface of the diaphragm 5. A step 7 is provided on the outer peripheral surface of the retainer ring 7.
When the wafer holding head 1 is lifted by the elevating mechanism 118, the step 7a and the locking portion 10
Engages with each other to suppress excessive downward movement of the retainer ring 7 so that a local force is not applied to the diaphragm 5.

A plurality of torque transmitting mechanisms 20 are provided on the upper surface of the carrier 6. As shown in FIGS. 1 and 2, the torque transmission mechanism 20 has a plate-like first member 2 formed to extend downward from the lower surface of the top plate 3 along the circumferential direction.
0a and a second member 2 having a U-shaped cross section provided on the upper surface of the carrier 6 so as to correspond to the first member 20a, respectively.
0b. First member 20a and second member 20b
The first member 20a has its front end located inside the U-shape of the second member 20b. Note that the second member 20b of the torque transmission mechanism 20 and the carrier 6 may be connected via the diaphragm 5.

The tip of the first member 20a and the second member 2
The carrier 6 has an interval from the inside of the U-shape so that the movement of the carrier 6 in the axial direction is not hindered. That is, the second member 20b is provided so as to be movable in the axial direction with respect to the first member 20a together with the carrier 6.

The torque transmitting mechanism 20 is for transmitting the torque of the head main body 2 to the carrier 6 when the head main body 2 is rotated during the polishing of the wafer W. That is, when the head main body 2 is rotated in the direction of arrow A in FIG. 2 during polishing of the wafer W, the carrier 6 supported by the diaphragm 5 exerts a frictional force between the wafer W held by itself and the polishing pad 102. Is rotated in the direction of arrow A while being twisted in the direction of arrow B. At this time, the one side of the first member 20a and the U-shaped inside of the second member 20b are in contact with each other, so that the torque of the head main body 2 is transmitted to the carrier 6 while the torsional force acting on the diaphragm 5 is reduced. Thus, the wafer W is polished. At this time, the first member 20a and the second member 20b are slidable with each other in the axial direction, so that the floating effect of the carrier 6 is not hindered.

A sensor section 21 is provided on a part of the side surface of the first member 20a. The sensor section 21 is provided in parallel with the plane portion of the second member 20b oriented in the rotation direction, and is provided on the side pressed into the second member 20b when the wafer holding head 1 rotates. Have been.

That is, when the wafer holding head 1 is not rotated, the torque transmitting mechanism 20 moves between the surface of the sensor unit 21 and the inside of the second member 20b so as not to hinder the swinging of the carrier 6 in the axial direction. Are slightly separated from each other. Then, when the wafer holding head 1 is rotated, the first member 20a on which the sensor unit 21 is installed is provided.
The sensor unit 21 is provided on a side on which one side surface and a surface inside the second member 20b are pressed.

A pressure sensor, such as a piezoelectric element or a strain gauge, is used for the sensor section 21 to detect a pressing force between the first member 20a and the second member 20b generated by the rotation of the wafer holding head 1. And That is, when the wafer W is polished, the force in the rotational direction acting on the wafer W is applied to the carrier 6 by the sensor unit 21.
Is directly detected via.

When the wafer holding head 1 is not rotated, the surface of the sensor section 21 and the second member 2
The inside of Ob may be in a state where it is slightly contacted so as not to hinder the swing of the carrier 6 in the axial direction. Also,
The sensor unit 21 may be provided on a portion pressed when the wafer holding head 1 is rotated, and may be provided on a plane portion on the second member 20b side, for example. Further, the first member 20a may be formed in a U-shaped cross section and the second member 20b may be formed in a plate shape, or the first and second members 20a and 20b may be formed in plate shapes, respectively. .

As shown in FIG. 3, the torque transmitting mechanism 20 provided with the sensor section 21 is provided at a plurality of positions in the circumferential direction on the upper surface of the carrier 6 of the wafer holding head 1 and has a rotational shaft center. Are provided at the same distance from each other in the radial direction.

Each sensor unit 21 is connected to the calculation unit 31 by a harness 31a inserted through the shaft unit 9 connected to the spindle. Also, the sensor unit 2
A harness for connecting the sensor unit 1 to a driving unit (not shown) for driving the sensor unit 21 is also provided so as to pass through the shaft unit 9. Output signals from these sensor units 21 are sent to the arithmetic unit 31 by the harnesses 31a connected thereto, and the arithmetic unit 31 receives the output signals from the respective sensor units 21 and acts on the wafer W. It is designed to output force.

The wafer holding head 1 configured as described above is connected by screwing the external thread 8 to the carousel. When polishing the wafer W using the wafer holding head 1, first, the wafer W
Is attached to the wafer attachment sheet 6a provided on the lower surface of the wafer. Then, while the periphery of the wafer W is locked by the retainer ring 7, the surface thereof is brought into contact with the polishing pad 102 attached to the upper surface of the platen 103. The material of the polishing pad 102 may be any material that has been conventionally used for polishing a wafer. For example, a velor-type pad in which a nonwoven fabric made of polyester or the like is impregnated with a soft resin such as a polyurethane resin, or a polyester A suede-type pad having a foamed resin layer made of foamed polyurethane or the like formed on a nonwoven fabric made of nonwoven fabric or the like, or a foamed resin sheet made of independently foamed polyurethane or the like is used.

Next, a fluid such as air is supplied from the pressure adjusting mechanism 30 to the flow path 15. The supplied fluid is in the fluid chamber 1
4 The flowed fluid adjusts the pressure in the fluid chamber 14 and adjusts the pressing pressure of the carrier 6 and the retainer ring 7 against the polishing pad 102. The carrier 6 and the retainer ring 7 have a floating structure supported by the diaphragm 5 and capable of being independently displaced in the vertical direction, and the pressure applied to the polishing pad 102 can be adjusted by the pressure inside the fluid chamber 14. ing.

The carrier 6 and the retainer ring 7
The platen 103 is rotated while adjusting the pressing pressure of the wafer holding head 1 on the polishing pad 102.
Is rotated in a planetary manner, and at the same time, the polishing agent is supplied to the surface of the polishing pad 102 and the polishing surface of the wafer W from the polishing agent supply means (not shown), whereby the wafer W is polished.

The wafer W to be polished and the polishing pad 102
The carrier 6 holding the wafer W is twisted with respect to the head main body 2 by the force acting between the head body 2. At this time, the sensor unit 21 provided on the torque transmission mechanism 20 on the upper surface of the carrier 6 is pressed by a flat portion inside the second member 20b and outputs a signal corresponding to the pressing force. That is, the sensor unit 21 outputs an output signal corresponding to a force acting between the wafer W and the polishing pad 102 to the arithmetic unit 3.
Send to 1.

The operation section 31 outputs a force acting on the wafer W based on output signals from the plurality of sensor sections 21 provided. At this time, a rotational force T generated in the rotation direction of the wafer W by rotating on the polishing pad 102 and a polishing force F generated in the rotational direction of the polishing pad 102 by the rotation of the polishing pad 102 are applied to the wafer W. The calculation unit 31 calculates the rotational force T and the polishing force F.

The rotational force T is generated by the rotation of the wafer W, and differs between the inner diameter position and the outer diameter position of the wafer W. That is, when the wafer W is rotated at a constant rotation speed by the wafer holding head 1, the polishing pad 1 is moved between the inner diameter position and the outer diameter position.
Since the speed with respect to the wafer 02 is different, the force acting on the wafer W is also different between the inner diameter position and the outer diameter position. That is, the rotational force T is related to the difference in the polishing rate between the inner diameter position and the outer diameter position of the rotating wafer W, and acts on the rotation direction of the wafer W.

On the other hand, the polishing force F is generated by the rotation of the polishing pad 102 and acts uniformly on the entire polishing surface of the wafer W. That is, the polishing force F is generated by the relative motion between the rotating polishing pad 102 and the wafer W, and is related to the rotation speed of the polishing pad 102 and the rotation of the polishing pad 102 on the polishing surface of the wafer W. It acts in the direction.

Although the polishing force F acts on the entire polished surface of the wafer W, the force detected by the sensor unit 21 is applied via the carrier 6, so that, as shown in FIG. Resultant force acting on the center position of At this time, in the outer peripheral portion of the wafer W, at a position a where the tangential direction of the rotating wafer W and the rotation direction of the polishing pad 102 coincide, the polishing pad 102
The force acting on the wafer W due to the rotation is F / 2. Further, it is assumed that a rotational force T is acting in the rotational direction of the wafer W. Since the four sensor units 21 provided along the circumferential direction of the carrier 6 are installed with their sensitivity directions directed toward the rotation direction of the wafer holding head 1, the sensor unit 21 is moved to the position a. The force Fa acting on the portion 21 is as follows: Fa = F / 2 + T (1)

Similarly, the force Fb acting on the sensor unit 21 moved to the position b on the inner peripheral side of the polishing pad 102 is Fb = F / 2−T (2) Therefore, from the equations (1) and (2), Fa + Fb = F (3), and the polishing force F can be obtained.

The sensor unit 21 moved to the position c in the rotational direction of the polishing pad 102, which is at right angles to positions a and b, changes its sensitivity direction to the rotational direction of the wafer holding head 1. Since it is installed facing, only the rotational force T generated by the rotation of the wafer holding head 1 is detected. That is, at the position c,
Since the sensitivity direction of the sensor unit 21 and the rotational direction of the polishing pad 102 are in a vertical relationship, the sensor unit 21 does not detect the polishing force F generated by the relative movement between the wafer holding head 1 and the polishing pad 102. Therefore, the force Fc acting on the sensor unit 21 moved to the position c is Fc = T (4) Similarly, the force Fd acting on the sensor unit 21 moved to the position d is Fd = T (5) Therefore, equation (3), equation (4) (or (5)
From the formula, the rotational force T and the polishing force F acting on the wafer W can be derived. The sum of “the number of rotations of the carousel per unit time” and “the number of rotations of the wafer holding head 1 per unit time” is “platen 10
In general, when the number of rotations per unit time is equal to "3, the number of rotations per unit time", no torque acts on the carrier 6.

The output signal observed from one sensor unit 21 during one rotation of the wafer holding head 1 is a force Fa which is a maximum value, a force Fb which is a minimum value, and a force which is observed at an intermediate time therebetween. Fc and force Fd. That is, the output signal from one sensor unit 21 fluctuates sinusoidally, and the rotation time (rotation speed) of the wafer holding head 1
Is known in advance, the rotational force T of the wafer W is
The polishing force F can be detected by one sensor unit 21. As described above, the polishing force F and the rotational force T can be obtained by detecting the signal output from one sensor unit 21 every moment.

At this time, the arithmetic unit 31 receives the outputs from the two sensor units 21 arranged at the positions a and b at the same time, thereby polishing the wafer W while polishing the wafer W.
Can be detected. That is, the polishing force F can be calculated by providing the two sensor units 21 according to the equations (1), (2), and (3).

Therefore, at least two sensor units 21 are installed on the upper surface of the carrier 6 and these sensor units 21 and 21 are installed facing each other at a position radially equal from the center of rotation of the carrier 6. , The polishing force F or the rotational force T can be detected while polishing the wafer W.

Further, in addition to the two sensor units 21 and 21 arranged at the positions a and b, the sensor unit 21 is arranged at the position c which is at a right angle to the positions a and b,
The detection of the polishing force F and the rotation force T can be performed simultaneously. That is, the polishing force F is obtained from the equations (1), (2) and (3).
Can be calculated, and equation (4) (or (5)
From the equation, the rotational force T is derived.

To this end, three sensor units 21 are provided on the upper surface of the carrier 6, and two of them are arranged so as to face a position at an equal distance in the radial direction from the rotation center of the carrier 6, and the other 1 One of the two sensor units 2
1 at right angles to the polishing force F
And the rotational force T can be simultaneously detected while polishing the wafer W.

Further, by providing at least four sensor portions 21 on the upper surface of the carrier 6, the force acting on the wafer W during the polishing of the wafer W can always be detected. That is, when three sensor units 21 are provided, for example, when the sensor unit 21 located at the position c is disposed at the position a by the rotation of the wafer holding head 1, the sensor unit is located at the opposed position (that is, the position b). 21 does not exist. Therefore, in this state, the arithmetic unit 31 cannot derive the polishing force F.

Therefore, at least four sensor sections 21 are provided on the upper surface of the carrier 6 and two
By disposing one of the two at a position equidistant from the center of rotation of the carrier 6 in the radial direction and the other two at a right angle to the two sensor units 21,
The polishing force F and the rotational force T can always be detected simultaneously while polishing the wafer W.

As described above, by providing a plurality of, preferably four or more, sensor units 21, the polishing force F and the rotational force T
Can be detected at the same time. Further, as shown in the equation (3), the polishing force F is derived based on the respective outputs from the two sensor units 21 arranged opposite to each other. Therefore, at least two sensor units 21 and 21 are
The polishing force F is detected by arranging the sensor units 21 at opposite positions at equal distances in the radial direction with respect to the center of rotation, that is, by providing the sensor units 21 at even positions as a whole.

The wafer W is polished while observing the polishing force F and the rotational force T output from the calculation unit 31. If the wafer W has not been sufficiently polished yet,
The polishing force F and the rotation force T, which are the outputs from, show fluctuated values. Therefore, when the output from the arithmetic unit 31 is in a fluctuating state, it is determined that the wafer W has not been sufficiently polished yet, and the polishing of the wafer W is continued.

Then, when the polished surface of the wafer W is flattened and a desired polished surface is obtained, the polishing force F and the rotational force T output from the arithmetic unit 31 show stable values. Therefore, when the output from the arithmetic unit 31 becomes stable and shows a substantially constant value, it is determined that the polished surface of the wafer W has reached a desired state. Then, the pressure of the fluid chamber 14 of the wafer holding head 1 is gradually reduced to reduce the pressing force between the wafer W and the polishing pad 102, thereby finishing the polishing of the wafer W.

As described above, by providing the torque transmitting mechanism 20 on the upper surface of the carrier 6, the torque of the head main body 2 can be accurately transmitted to the carrier 6 even in the configuration having the diaphragm 5 which is an elastic body. Thus, excessive force in the rotating direction is not applied to the diaphragm 5. Therefore, the deterioration of the diaphragm 5 can be prevented, and a stable floating effect can be maintained for a long time.

The torque transmitting mechanism 20 has a sensor 21
Is provided, the force acting on the wafer W is directly detected by the sensor unit 21 via the carrier 6. That is, even when the lower surface of the retainer ring 7 that is arranged concentrically around the wafer W is in contact with the polishing pad 102, the force acting on the wafer W causes the force acting between the retainer ring 7 and the polishing pad 102. The state of the polished surface of the wafer W can be accurately determined because it is observed by the sensor unit 21 without being affected by the acting force.

The outputs from the plurality of sensor units 21 are calculated by a calculation unit 31, and the calculation unit 31 outputs a force acting on the wafer W during polishing of the wafer W. Therefore, since the polishing of the wafer W is performed while observing the force acting on the wafer W, the polishing is performed while determining whether the polished surface of the wafer W has reached a desired state. Therefore, generation of a wafer such as overpolishing or insufficient polishing can be reduced, and stable polishing of the wafer W can be realized.

Further, since the sensor portion 21 is provided at the contact portion between the first member 20a and the second member 20b, even if the wafer holding head 1 is in the rotating state, the force acting on the wafer W is reliably detected. Is done. Further, since the second member 20b is provided so as to be displaceable with respect to the first member 20a, the displacement of the carrier 6 and the retainer ring 7 supported by the diaphragm 5 in the axial direction is not hindered. The polishing of W is performed stably.

The plurality of sensor units 21 are provided at the same radial distance from the center of rotation of the carrier 6 as shown in FIG. 5, but as shown in FIG. The respective distances L1 from the rotation center of the carrier 6 of 21p, 21p may be different from the respective distances L2 from the rotation center of the carrier 6 of the other opposing sets of sensor units 21q, 21q. .
In this case, the sensor units 21p and 21p can detect the rotational force T1 at the distance L1, while the sensor unit 2p
1q and 21q can detect the rotational force T2 at the distance L2. That is, the opposing sensor units 21 and 21
, The rotational forces T1, T2,... At various positions in the radial direction of the wafer W can be detected.

Further, as shown in FIG. 6A, one or both of the contact portions of the first and second members 20a and 20b may be formed in a round bar shape. By forming the first and second members 20a and 20b in a round bar shape, the contact area of each can be reduced, so that the vertical swinging (floating effect) of the carrier 6 is performed more stably. Further, as shown in FIG. 6B, the sensor unit 21 is connected to the top plate 3 and the first member 20a.
(Or between the carrier 6 and the second member 20b)
And the rotational force acting on the wafer W can be detected by the shear force generated at this position. In this case, a shear force can be detected by using a piezoelectric element as the sensor unit 21. Further, by employing a configuration in which a shear force is detected using a piezoelectric element, forces acting in a plurality of directions can be simultaneously detected by one sensor unit 21, and the number of sensor units 21 to be installed can be reduced. Can be.

Further, as shown in FIG.
Is driven by the driving circuit of the driving / amplifying circuit unit 32 installed on the upper surface of the head main body 2, and
An output signal from the sensor unit 21 may be sent to the calculation unit 31 via an amplification circuit in the drive / amplification circuit unit 32. At this time, the harness 32 a connecting the sensor unit 21 and the drive / amplification circuit unit 32 is provided so that a part of the top plate 3 of the head main body 2 is inserted. Since the driving / amplifying unit 32 is installed in the head main body 2, the harness 32a can be formed to be short.
The sensor unit 21 is hardly affected by noise.

Although the torque transmitting mechanism 20 having the sensor 21 is provided on the upper surface of the carrier 6, the torque transmitting mechanism 40 having no sensor 21 may be provided on the upper surface of the retainer ring 7. is there. By providing the torque transmission mechanism 40 also on the upper surface of the retainer ring 7, the torque of the head main body 2 is accurately transmitted to the diaphragm 7, and the excessive rotational force is not applied to the diaphragm 5. Thus, the deterioration of the diaphragm 5 is prevented, and a stable floating effect can be maintained for a long time.

Next, the wafer holding head 1 according to the present invention
An example in which the wafer W is polished by using the method will be described. FIG. 8A is a diagram in which the sensitivity directions of the four sensor units 21a, 21b, 21c, and 21d provided on the wafer holding head 1 are indicated by arrows. In this case,
The sensitivity direction of the sensor units 21a and 21c is directed in the radial direction of the wafer holding head 1, and
1d is oriented in the rotation direction of the wafer holding head 1. FIG. 8B is a diagram showing a state in which the wafer holding head 1 is arranged on the upper surface of the polishing pad 102, where r1, r2, r3, and r4 indicate the wafer holding head 1.
Are rotated, the respective sensor units 21a to 21a to
The position at which 21d is arranged is shown. For example, the sensor unit 21a is arranged at the position of r1, r2, r3, r4 in order by rotating the wafer holding head 1 in the direction of arrow y1. At this time, the polishing pad 102 indicates an arrow y2.
, And the wafer holding head 1 is revolved in the direction of arrow y3 by the carousel.

By polishing the wafer W, for example, as shown in FIG. 9A, a sine wave output signal g1 having a high frequency component is output from the sensor units 21a and 21c. The output signal g2 passes through a low-pass filter provided in the arithmetic unit 31.
Is converted to Then, by reading the change in the maximum value of the output signal g2, the polishing state of the wafer W is observed. On the other hand, from the sensor units 21b and 21d, FIG.
Waveforms as shown in (b) and (c) are output. 9B shows “the number of rotations of the carousel per unit time” + “the number of rotations of the wafer holding head 1 per unit time” = “the number of rotations of the polishing pad 102 per unit time”.
Is satisfied, the torque observed on the carrier 6 does not act on the carrier 6 as described above. FIG. 9C shows a waveform when the above relationship does not hold. Since torque is acting on the carrier 6, waveforms corresponding to this value are output from the sensor units 21b and 21d.

FIGS. 10 (a1) and 10 (b1) show configurations of two types of wafers W1 and W2 to be polished. FIG.
The wafer W1 shown in (a1) has Cu in the groove of the SiO2 layer.
Should be polished so as to be embedded. In this case, the polishing end point is to polish the Cu layer so that the barrier metal layer is exposed on the surface, and at the same time, the barrier metal layer and the C
u is flattened. On the other hand, FIG.
Is to be polished so as to flatten the oxide film, and the polishing end point in this case is a state where the oxide film is flattened. 10 (a2), (b)
2) is an output value from the arithmetic unit 31 at this time,
The change of the maximum value of each output signal g2 is shown.

In the wafer W1, the Cu layer to be polished is gradually flattened to increase the contact area with the polishing pad 102, so that the frictional force is increased.
As shown in (a2), the value of the output signal at this time gradually increases. Then, when the Cu layer is further polished and the barrier metal layer appears on the surface, the output signal sharply drops because the barrier metal layer has a lower coefficient of friction than the Cu layer. This state where the output signal sharply drops is the polishing end point, and polishing is terminated at this point. In the wafer W2, the polishing end point is a state where the oxide film is flattened. Therefore, the polishing is terminated when the oxide film is flattened and the maximum value of the output signal is stabilized for a certain period of time. That is, FIG. 10 (b1),
As shown in (b2), the time point h1 when the oxide film is flattened
Are further polished, and the polishing is terminated at a time point h2 when the maximum value of the output signal is stabilized for a certain period of time.

[0066]

The wafer polishing apparatus and the wafer manufacturing method of the present invention have the following effects.

According to the first aspect of the present invention, the torque transmission mechanism is provided on the upper surface of the carrier, so that the torque of the head main body is accurately transmitted to the carrier even in the configuration having the diaphragm as an elastic body. At the same time, the diaphragm is prevented from being subjected to an excessive force in the rotating direction, so that the deterioration of the diaphragm is prevented. In addition, since the sensor portion is provided in the torque transmission mechanism, the force acting on the wafer is directly observed on the sensor portion via the carrier, so that, for example, a portion other than holding the wafer of the wafer holding head such as a retainer ring. Is accurately detected even in the state in which it comes into contact with the polishing pad. Then, the calculation unit calculates the force acting on the wafer based on the outputs from the plurality of sensor units.

According to the second aspect of the present invention, since the sensor portion is provided at the contact portion between the first member and the second member,
Even when the wafer holding head is in a rotating state, the force acting on the wafer is reliably detected. Furthermore, since the second member is provided so as to be displaceable with respect to the first member, the displacement of the carrier and the retainer ring supported by the diaphragm in the axial direction is not hindered, and the polishing of the wafer is stable. It is done.

According to the third aspect of the present invention, according to the present invention, the force acting on the wafer is directly observed by the sensor section provided on the upper surface of the carrier, and the polishing state of the wafer is measured from the sensor section. It is determined based on the output. Therefore, occurrence of wafers such as overpolishing or insufficient polishing is reduced, and stable wafer polishing is realized.

[Brief description of the drawings]

FIG. 1 is a sectional view of a wafer holding head in a view showing an example of an embodiment of a wafer polishing apparatus of the present invention.

FIG. 2 is a sectional view illustrating a torque transmission mechanism and a sensor unit.

FIG. 3 is a diagram illustrating an arrangement of a torque transmission mechanism and a sensor unit.

FIG. 4 is a diagram illustrating a state where a force acting on a wafer is detected by a sensor unit.

FIG. 5 is a diagram illustrating an arrangement of a torque transmission mechanism and a sensor unit.

FIG. 6 is a cross-sectional view of a wafer holding head in a diagram illustrating an example of an embodiment of a wafer polishing apparatus of the present invention.

FIG. 7 is a sectional view showing another embodiment of the torque transmission mechanism and the sensor unit.

FIG. 8 is a view showing an embodiment of the wafer polishing apparatus of the present invention, and is a view for explaining a mounting position and a sensitivity direction of a sensor unit.

FIG. 9 is a diagram illustrating an output signal from a sensor unit.

FIG. 10 is a cross-sectional view showing a layer configuration of a wafer and a diagram for explaining an output result from an arithmetic unit when these wafers are polished.

FIG. 11 is a diagram illustrating the entire wafer polishing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Wafer holding head 2 Head main body 3 Top plate part 4 Peripheral wall part 5 Diaphragm 6 Carrier 7 Retainer ring 9 Shaft part 14 Fluid chamber 15 Flow path 20 Torque transmission mechanism 20a First member 20b Second member 21 Sensor part 30 Pressure adjustment mechanism 31 Calculation unit 102 Polishing pad 103 Platen W Wafer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 622 H01L 21/304 622R F-term (Reference) 2F051 AA11 AB02 AC01 AC09 BA03 3C034 AA13 AA17 CA16 CB01 DD10 DD20 3C043 BA09 BA16 CC07 DD05 3C049 AA07 AA12 AB04 AB06 AB08 BA06 BB09 BC01 BC02 CB01 3C058 AA07 AA12 AB04 AB06 AB08 BA06 BB09 BC01 BC02 CB01 DA12 DA17

Claims (3)

[Claims] A platen having a polishing pad affixed to a surface thereof; and a wafer holding head for holding a wafer to be polished and bringing one surface of the wafer into contact with the polishing pad. A wafer polishing apparatus for polishing the wafer with the polishing pad by rotating the wafer pad, wherein the wafer holding head comprises a top plate portion and a cylindrical peripheral wall portion provided below the outer periphery of the top plate portion. A head body comprising: a diaphragm extending perpendicularly to a head axis in the head body; and a pressure adjusting mechanism for adjusting a fluid pressure filled in a fluid chamber formed between the diaphragm and the head body. And fixed to the diaphragm and provided so as to be displaceable in the head axis direction together with the diaphragm, and one surface of the wafer to be polished is And a carrier for holding, concentrically disposed between the inner wall of the peripheral wall portion and the outer periphery of the carrier, fixed to the diaphragm and provided so as to be displaceable in the head axis direction together with the diaphragm, and polished during polishing. A plurality of retainer rings that are in contact with the pad; a plurality of torque transmission mechanisms provided circumferentially between the head body and the carrier for transmitting torque of the head body to the carrier; A plurality of sensor units provided in the mechanism and for observing the force in the rotational direction acting on the wafer, are connected to the respective sensor units, and calculate a force acting on the wafer based on outputs from these sensor units. A wafer polishing apparatus, comprising: 2. The wafer polishing apparatus according to claim 1, wherein the torque transmission mechanism is provided on a first member formed to extend downward from a lower surface of the top plate portion, and provided on an upper surface of the carrier. A second member that is in contact with a part of the first member in the rotation direction of the wafer holding head and is displaceable in the axial direction with respect to the first member during polishing; A wafer polishing apparatus provided at a contact portion between a first member and a second member. 3. A platen having a polishing pad attached to a surface thereof, and a wafer holding head for holding a wafer to be polished and bringing one surface of the wafer into contact with the polishing pad, wherein the wafer holding head and the platen A polishing step of polishing the wafer with the polishing pad by rotating each of the wafers, wherein the wafer holding head is provided below the top plate and the outer periphery of the top plate. A head body composed of a cylindrical peripheral wall portion; a diaphragm stretched in the head body perpendicular to the head axis; and a fluid pressure filled in a fluid chamber formed between the diaphragm and the head body. A pressure adjusting mechanism for adjusting the pressure, and being provided on the diaphragm so as to be displaceable in the head axis direction together with the diaphragm, and for polishing. A carrier for holding one surface of the wafer, and disposed concentrically between the inner wall of the peripheral wall portion and the outer periphery of the carrier, and fixed to the diaphragm and provided so as to be displaceable in the head axis direction together with the diaphragm. And a retainer ring that abuts against a polishing pad during polishing, a plurality of torque transmission mechanisms provided in a circumferential direction between the head body and the carrier, and for transmitting torque of the head body to the carrier, A plurality of sensor units provided in each of the torque transmission mechanisms and for observing a rotational force acting on the wafer, are connected to the respective sensor units, and based on outputs from these sensor units, And a calculation unit for calculating an acting force. The wafer held by the wafer holding head is While rotating while making contact with the polishing pad, a force acting on the wafer is calculated by the calculation unit based on an output from each sensor unit, and a polishing state of the wafer is determined based on an output from the calculation unit. A wafer manufacturing method characterized by performing polishing while polishing.