JP2000331969A - Wafer-polishing device and manufacture of wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the polishing ending point of a wafer detectable stably. SOLUTION: A rotatably supported spindle 1 is provided with a spindle-side connecting section 4 for connecting the spindle 1 to a wafer holding head. In the outer pipe section 17 of the connecting section 4, a position adjusting member 18 having a flange section 18b is provided and a plurality of pressure sensors 20 composed of piezoelectric elements are arranged in the circumferential direction on the flange section 18b. Since the force applied to a wafer is detected by means of the sensors 20, the polishing ending point of the wafer can be detected from the output signal of the sensors 20.

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 SiO2, a neutral solution using SeO2, an acidic solution using Al2O3, an abrasive, etc. As a method of flattening, there is a wafer polishing apparatus used in this method, for example, as shown in FIG.

In FIG. 6, 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, for example, fluctuations in the rotational power of a platen driving mechanism are observed in order to detect whether the polished surface of the wafer W has reached a desired state. I was That is, when the polishing of the wafer W is insufficient, the frictional force generated between the polishing pad 102 and the wafer W is in a fluctuating state.
When the wafer W is polished to a desired polishing surface, it becomes stable. At this time, since the platen 103 is rotated at a constant speed, for example, when the polishing resistance is large, the rotational power of the platen driving mechanism becomes large, and when the polishing resistance is small, the rotational power becomes small. Then, the fluctuation of the rotational power of the platen driving mechanism 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, in the method for observing the fluctuation of the rotational power of the platen driving mechanism, the polishing end point cannot be individually detected for the plurality of wafer holding heads 101, and the wafer W cannot be detected. In some cases, over-polished products and under-polished products are produced, and over-polished products and under-polished products are mixed.

The platen 103 is often idle even when the wafer W and the polishing pad 102 are not in contact with each other. At this time, for example, when the wafer W is originally made of a material having a low polishing resistance, Since the rotation power fluctuation of the platen driving mechanism between the polishing state of W and the completion state of W is small, it is mixed with the idling power component of the platen 103, and it is difficult to detect the polishing end point of the wafer W.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a wafer polishing apparatus and a method of manufacturing the same, which can stably detect a state in which polishing of a wafer has been completed. .

[0011]

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 holding head that abuts one surface thereof, and a wafer polishing apparatus that polishes the wafer with the polishing pad by a relative movement between the wafer holding head and the platen, wherein the wafer holding head has an upper part. A sensor for observing a force acting on the wafer during polishing is provided on one surface of a portion of the spindle that is rotatably supported by the connected spindle and that is connected to the wafer holding head. A wafer polishing apparatus characterized by the following.

According to the present invention, by providing the sensor at the connection portion between the spindle and the wafer holding head, even when a plurality of wafer holding heads are provided, the force acting on the wafer held by each wafer holding head is provided. Can be observed. Therefore, stable polishing end point detection can be performed without causing a wafer in an over-polished state or a poorly-polished state. Further, since the sensors are provided on the spindle side, it is not necessary to install the sensors on the individual wafer holding heads, and the number of sensors to be used can be reduced.

According to a second aspect of the present invention, there is provided the wafer polishing apparatus according to the first aspect, wherein the wafer holding head is provided at an upper portion thereof and has a cylindrical shaft portion having a threaded portion on an outer peripheral surface. Wherein the spindle comprises a cylindrical outer cylindrical portion that opens downward, a female screw portion formed on the inner peripheral surface of the outer cylindrical portion and screwed with the male screw portion, and the outer cylindrical portion. A contact surface that is provided inside and that is disposed at a position that comes into contact with the upper end surface of the shaft portion when the male screw portion and the female screw portion are screwed together, and the sensor has a contact surface A plurality of wafer polishing apparatuses are arranged at intervals in a circumferential direction.

According to the present invention, the spindle and the wafer holding head are stably connected by screwing the female screw portion and the male screw portion formed respectively. Then, by disposing the sensor at a portion which is in contact with the upper end surface of the shaft portion, the force acting on the wafer is reliably observed by the sensor via the wafer holding head.

According to a third aspect of the present invention, there is provided the wafer polishing apparatus according to the first aspect, wherein the wafer holding head has a cylindrical shaft portion provided on an upper portion thereof and having a thread portion on an outer peripheral surface. Wherein the spindle is connected to a lower portion of the spindle shaft main body, and has a cylindrical outer cylinder portion opened downward, and a female formed on an inner peripheral surface of the outer cylinder portion to be screwed with the male thread portion. A screw portion, one surface of which is provided inside the outer cylinder portion and abuts against the lower end surface of the shaft main body, and the other surface contacts the upper end surface of the shaft portion when the male screw portion and the female screw portion are screwed. And a position adjustment member,
A plurality of the sensors are arranged at intervals in a circumferential direction of a contact surface between a lower end surface of the shaft main body and a position adjusting member.

According to the present invention, a position adjusting member is provided between the spindle and the wafer holding head, and the position of the wafer holding head connected to the spindle is adjusted by changing the thickness of the position adjusting member. It becomes possible. And, by disposing the sensor at the portion where the lower end surface of the spindle shaft body and the position adjusting member abut, the force acting on the wafer can be reliably observed by the sensor via the wafer holding head.

[0017] The invention according to claim 4 is the invention according to claims 1, 2,
3. The wafer polishing apparatus according to claim 3, wherein the sensor includes a piezoelectric element.

According to the present invention, by using the piezoelectric element for the sensor, the vertical force and the shear force acting on the wafer can be observed, and the reduction in the rigidity of the apparatus can be minimized. Can be suppressed.

According to a fifth 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 the relative movement between the wafer holding head and the platen, wherein the upper portion of the wafer holding head is horizontally rotatably supported by a spindle, A sensor for observing a force acting on the wafer during polishing is provided on one surface of a connection portion of the spindle with the wafer holding head, and polishing is performed while detecting a polishing state of the wafer based on an observation result of the sensor. And a method for manufacturing a wafer.

According to the present invention, even when a plurality of wafer holding heads are installed, polishing can be performed while reliably observing the forces acting on each wafer.
Therefore, it is possible to prevent the production of a wafer in an over-polished state or an insufficiently polished state, and to realize efficient production of a wafer.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a wafer polishing apparatus according to one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a sectional view showing a spindle 1 in one embodiment of the wafer polishing apparatus of the present invention.

The spindle 1 is installed, for example, at a portion connecting the carousel and the wafer holding head shown in FIG.

In FIG. 1, the spindle 1 is provided inside an engaging portion 22 which is a through hole formed in a spindle housing 16 provided in the carousel 2.
The spindle 1 has a shaft main body 1a formed in a substantially cylindrical tube shape, a spindle-side connecting portion 4 disposed at a lower portion of the carousel 2, a handle support portion 9 disposed at an upper portion of the carousel 2, and a handle supporting portion 9. An adjustment handle 8 is provided to extend from the section 9 in the horizontal direction, and a fluid supply port 10 is provided on the upper end side and communicates with the conduit 1b of the shaft main body 1a. The first bearing 3 is provided inside the engaging portion 22, and the shaft main body 1 a is rotatably supported by the first bearing 3. An upper flange portion 15 is provided on the upper surface of the carousel 2. And
The spindle 1 and the carousel 2 are connected by mounting screws 2a.

The first bearing 3 is fitted inside the cylindrical engaging portion 22 of the spindle housing 16. At this time, the first bearing 3 is slidably supported in the axial direction inside the engaging portion 22,
The outer periphery of the bearing 3 and the inner periphery of the engaging portion 22 are not fixed. In addition, the relative positions of the first bearing 3 and the shaft main body 1a in the axial direction are provided so as not to be changed.

On the lower surface of the spindle housing 16, an annular convex portion 16a formed in an annular shape is doubly formed vertically downward. An annular locking portion 16b protruding in the radial direction is formed in the lower portion of the inner periphery of the first bearing 3, and the first bearing 3 slidably supported.
Is regulated downward movement. At this time, the locking portion 16
It is also possible to provide an annular leaf spring 25 on the upper surface of b, and this leaf spring 25 reduces the impact when the lower part of the first bearing 3 and the locking portion 16b are in contact. .

A bearing support 5 is provided inside the upper flange 15 formed in a cylindrical shape. The bearing support portion 5 is formed in a tubular shape, and a position adjusting male screw portion 6 is formed at a lower portion of the outer peripheral surface. The position adjusting male screw portion 6 is adapted to be screwed with a position adjusting female screw portion 13 formed on the upper portion of the inner peripheral surface of the spindle housing 16. At this time, the width of the position adjusting female screw portion 13 in the axial direction is larger than the width of the position adjusting male screw portion 6 in the axial direction. Further, the outer peripheral surface of the bearing support portion 5 is in contact with the inner peripheral surface of the upper flange portion 15, and the bearing support portion 5 is rotatable inside the upper flange portion 15.

A second bearing 7 is provided inside the cylindrical shape of the bearing support portion 5, and the shaft main body 1a
The bearing is rotatably supported by the bearing 7 and the first bearing 3. In addition, a step 5a provided to support the second bearing 7 from below is formed below the bearing support 5, and the outer periphery of the second bearing 7 and the inner periphery of the bearing support 5 are fixed. ing. The second bearing 7 is formed by an angular ball bearing, and regulates the movement of the shaft main body 1a in the axial direction (thrust direction). For this reason, the relative position between the shaft main body 1a and the second bearing 7 is not changed.

Above the bearing support 5, a cylindrical handle support 9 is provided. This handle support 9
Is connected to the adjustment handle 8 which is fixed to the bearing support 5 by a bolt 14 and is provided so as to extend in the horizontal direction. At this time, the shaft main body 1a is rotatable inside the cylindrical shape of the handle support portion 9.
By rotating the handle support 9 together with the bearing support 5 using the adjustment handle 8, the shaft main body 1a is moved in the axial direction.

That is, the bearing support 5, the handle support 9, and the second bearing 7 are fixed, and the first bearing 3 is slidable with respect to the spindle housing 16. The movement of the shaft body 1a in the thrust direction is restricted by the second bearing 7, and the first bearing 3, the second bearing 7, and the shaft body 1
The position relative to “a” is provided so as not to change.

At this time, by rotating the bearing support 5, the position adjusting male screw 6 is rotated along the position adjusting female screw 13, and accordingly, the bearing support 5 is moved relative to the spindle housing 16. Is moved in the axial direction. Therefore, the shaft main body 1a is moved in the axial direction relatively to the spindle housing 16 fixed to the carousel 2 without changing the relative position with respect to the bearing support portion 5.

A scale 26 is provided above the handle support 9 so that the angle at which the handle 9 is rotated can be checked by the scale 26.

Above the spindle 1, a fluid supply port 10 is provided so as to communicate with the inside of the conduit 1b of the shaft main body 1a. A fluid such as air supplied from the fluid supply port 10 is sent to the lower opening side through the conduit 1b. A housing 11 is provided around the shaft main body 1a in the vicinity of the fluid supply port 10 to prevent fluid other than the fluid supplied from the fluid supply port 10 from entering the inside of the pipeline 1b. Note that a third bearing 12 is provided inside the housing 11, and the shaft body 1
It is configured not to hinder the rotation of a.

Carousel 2 Spindle 1 projecting downward
A spindle-side connection part 4 for connection with the wafer holding head is formed at the lower part of the head. The spindle connecting portion 4 includes an outer cylindrical portion 17 connected to the shaft main body 1 a and a cylindrical position adjusting member 18 provided inside the outer cylindrical portion 17.
And Further, by changing the thickness of the spacer 21 integrally provided above the position adjusting member 18, the position of the wafer holding head connected to the spindle side connecting portion 4 can be adjusted.

The position adjusting member 18 has a projection 18a formed in a cylindrical shape and projecting downward.
And a flange 18b formed so as to be continuous with the projection 18a, and a recess 18c which is a space inside the projection 18a. In addition, the pipe line 1 is provided inside the projection 18a.
supply pipe 18d formed in the vertical direction so as to communicate with
Are provided so as to penetrate to the lower end surface of the projection 18a.

On the inner peripheral surface of the outer cylinder portion 17, a head mounting female screw portion 19 is formed at a position facing the outer peripheral surface of the projection 18a. An annular concave portion 1 formed along the annular convex portion 16a is formed on the outer upper surface of the outer cylindrical portion 17.
7a is provided. That is, a labyrinth ring is formed by these, and a gap having a complicated shape is formed by the annular convex portion 16a and the annular concave portion 17a. Viscous friction resistance and surface tension act on this gap, and the first A liquid such as an abrasive or a foreign matter does not enter the bearing 3 side.

A pressure sensor 20 composed of a piezoelectric element is provided on the flange 18b. As shown in FIG. 3, a plurality of (three in this embodiment) pressure sensors 20 are arranged so as to be embedded at equal intervals in the circumferential direction of the flange portion 18b. A lead wire is connected to each pressure sensor 20, and is connected to an amplifier 20b provided at the upper end of the spindle 1 through a pipe 1b. Pressure sensor 20
Is sent to the amplifier 20b by a lead wire and transmitted to an external arithmetic unit.

Next, the wafer holding head mounted on the spindle 1 will be described with reference to FIG. In FIG. 2, the wafer holding head 50 is fixed to a head main body 52 including a top plate 53 and a peripheral wall 54 formed in a cylindrical shape, a diaphragm 55 stretched inside the head main body 52, and a lower surface of the diaphragm 55. Disc-shaped carrier 56, and annular retainer ring 5 provided concentrically on the inner wall of peripheral wall portion 54 and the outer peripheral surface of carrier 56.
7 is provided. The carrier 56 and the retainer ring 57 have a floating structure that can be moved in the axial direction by elastic deformation of the diaphragm 55.

The head main body 52 is composed of a disk-shaped top plate 53 and a cylindrical peripheral wall 54 fixed below the outer periphery of the top plate 53. The lower end of the head main body 52 is open and hollow. It has become. The top plate portion 53 is coaxially fixed to a shaft portion 59 which is a head-side connecting portion for connecting to the spindle 1.
The flow path 65 communicating with the pipeline 1b is formed in the vertical direction. On the outer peripheral surface of the shaft portion 59, a head mounting male screw portion 58 is formed. Further, a step portion 54a and an annular locking portion 60 protruding inward in the radial direction are formed on the lower portion of the peripheral wall portion 54 over the entire circumference.

The diaphragm 55 made of an elastic material such as fiber reinforced rubber is formed in an annular or disk shape.
It is fixed on a step portion 54 a formed on the inner wall of the peripheral wall portion 4 by a diaphragm fixing ring 61.

A fluid chamber 64 is formed above the diaphragm 55, and communicates with a flow path 65 formed in the shaft portion 59. Then, a fluid such as air is supplied into the fluid chamber 64 from the pipe 1b of the spindle 1 through the flow path 65, so that the pressure inside the fluid chamber 64 is adjusted.

The carrier 56 made of a high-rigidity material such as ceramic is formed in a substantially disc-like shape with a constant thickness, and is fixed by a carrier fixing ring 62 provided on the upper surface of the diaphragm 55. Carrier fixing ring 62
A stepped portion 62a is formed in an annular shape at the upper part of the nut, a nut 69 inserted vertically from the top plate portion 53, and a stopper bolt 68 fixed by a spacer 69a.
Is engaged with a step 68a formed at the lower end thereof. Then, even if the wafer holding head 50 is raised by, for example, the elevating mechanism 118 and the diaphragm 55 bends downward due to its own weight of the carrier 56 or the like, the stepped portion 6 is formed.
The engagement between the step 2a and the step 68a prevents an excessive force from acting on the diaphragm 55.

The retainer ring 57 is formed in an annular shape between the inner wall of the peripheral wall portion 54 and the outer peripheral surface of the carrier 56, and slightly between the inner wall of the peripheral wall portion 54 and the outer peripheral surface of the carrier 56. It is arranged concentrically with the peripheral wall portion 54 and the carrier 56 with an appropriate gap. Further, the retainer ring 57 has an upper end surface and a lower end surface formed horizontally, and is fixed by a retainer ring fixing ring 63 provided on the upper surface of the diaphragm 55. A step 57a is formed on the outer peripheral surface of the retainer ring 57. When the wafer holding head 50 is lifted by the elevating mechanism 118, the step 57a and the engaging portion 60 are engaged, so that the retainer ring is engaged. An excessive downward movement of the diaphragm 57 is suppressed, and a local force is not applied to the diaphragm 55.

A diaphragm 55 is provided on the upper surface of the carrier 56.
, A plurality of torque transmitting units 70 are provided. As shown in FIGS. 2 and 4, the torque transmitting portion 70 includes a first member 70 a having a U-shaped cross section fixed to the upper surface of the carrier 56.
And a rectangular parallelepiped second member 70b fixed to the top plate 53 above the first member 70a. The first member 70a is disposed with its planar portion facing in the circumferential direction, and the second member 70b has
0a is located inside the U-shape. The torque transmitting unit 70 stably transmits the rotational force of the spindle 1 to the carrier 56 during the polishing of the wafer W, reduces the torsional force acting on the diaphragm 55, and prevents the diaphragm 55 from being damaged. .

The torque transmitting section 70 is provided at at least two places in the circumferential direction. Also, the first member 70a
Is arranged so as to have an interval between the inside of the U-shape and the tip of the second member 70b so as not to hinder the movement of the carrier 56 in the axial direction. Note that the shape of the torque transmitting portion 70 is not limited to the above-described shape.
It is also possible that a is a pin-shaped member and the second member 70b is a cylindrical member.

The spindle 1 and the wafer holding head 50 configured as described above are connected to each other by screwing the head mounting female thread 19 and the head mounting male thread 58 formed respectively.

That is, first, the wafer holding head 50 is disposed below the spindle-side connecting portion 4 of the spindle 1, and the shaft portion 59, which is the head-side connecting portion, and the spindle-side connecting portion 4 are brought close to each other. At this time, the protrusion 18
a and the flow path 65 are fitted to each other so as to be close to each other while performing positioning. As described above, the spindle side connecting portion 4
By providing the position adjusting member 18 for performing centering, the center position between the spindle 1 and the wafer holding head 50 can be easily adjusted.

The head mounting internal thread 19 and the head mounting external thread 58 are screwed together while performing alignment. Then, the position adjusting member 1 provided inside the upper end surface of the shaft portion 9 of the wafer holding head 50 and the spindle side connecting portion 4.
8 until it comes into contact with the flange 18b. At this time, the flange portion 1 which is a portion to which the upper end surface of the shaft portion 9 contacts.
Since the pressure sensor 20 is provided on 8b, the upper end surface of the shaft portion 9 and the pressure sensor 20 are in contact with each other.

Then, the female screw portion 19 for mounting the head and the male screw portion 58 for mounting the head are screwed together until the upper end surface of the shaft portion 9 slightly presses the flange portion 18b provided with the pressure sensor 20. The connection between 50 and the spindle 1 is terminated.

When the wafer W is polished using the wafer holding head 50 connected to the spindle 1, the wafer W is first attached to a wafer attachment sheet 56 a provided on the lower surface of the carrier 56. Then, while the periphery of the wafer W is locked by the retainer ring 57, the surface thereof is brought into contact with the polishing pad 102 attached to the upper surface of the platen 103. The polishing pad 10
The material 2 may be any material that has been conventionally used for polishing a wafer. For example, a velor-type pad in which a soft resin such as a polyurethane resin is impregnated into a non-woven fabric made of polyester or the like, a non-woven fabric such as polyester is used. As the base material, a suede-type pad having a foamed resin layer made of foamed polyurethane or the like formed thereon, or a foamed resin sheet made of independently foamed polyurethane or the like is used.

Next, a fluid such as air is supplied to the fluid supply port 10 from a fluid supply means (not shown). The supplied fluid passes through the conduit 1 b and flows into the fluid chamber 64 from the flow path 65. The flowed fluid regulates the pressure in the fluid chamber 64 and regulates the pressing pressure of the carrier 56 and the retainer ring 57 against the polishing pad 102. The carrier 56 and the retainer ring 57 have a floating structure supported by the diaphragm 55 and can be independently displaced in the vertical direction, and the pressure inside the fluid chamber 64 can be adjusted by the pressure applied to the polishing pad 102. ing.

While adjusting the pressure of the carrier 56 and the retainer ring 57 against the polishing pad 102, the platen 103 is rotated, and the wafer holding head 50 is rotated in a planetary manner. At the same time, the wafer W is polished by supplying the polishing agent from the polishing agent supply means (not shown) to the surface of the polishing pad 102 and the polishing surface of the wafer W.

The polishing resistance acting on the wafer W in the vertical and circumferential directions is detected by the pressure sensor 20 abutting on the upper end surface of the shaft portion 59.

The pressure sensor 20 is made of a piezoelectric element, and can detect both a shearing force applied in the horizontal direction and a stress applied in the vertical direction. As for the force in the horizontal direction, both the force in the rotational direction (torque) and the force in the radial direction (right angle direction) can be detected.
In other words, the piezoelectric element utilizes the piezoelectric effect in which an external signal or the like is applied to the piezoelectric element to generate an electric signal at its output terminal. This piezoelectric element is roughly composed of electrodes provided at both ends and a piezoelectric ceramic which is a laminated body provided so as to be sandwiched between these electrodes, and generates a positive voltage when compressed from an initial state, for example. , When it is expanded, a negative voltage is generated. The pressure sensor 20 composed of the piezoelectric element is compressed to some extent in advance by fastening the spindle 1 and the wafer holding head 50. That is, the wafer W
Before the polishing, an initial state as if a bias voltage was applied is formed.

During polishing of the wafer W, a vertical force is applied to the pressure sensor 20 by bringing the wafer W of the wafer holding head 50 into contact with the polishing pad 102, so that the pressure sensor 20 is in a compressed state. . At this time, the pressure sensor 20 outputs, for example, a positive voltage, and this output signal is transmitted to the amplifier 20b by a lead wire, and a signal from the pressure sensor 20 provided outside is converted into a force value. The data is transmitted to a monitor or the like via a calculation unit for calculating.

When the wafer W is polished by the polishing pad 102, a frictional force is generated between the wafer W and the polishing pad 102. Then, a rotational force acts on the wafer holding head 50, and a shear force acts on the pressure sensor 20. At this time, the pressure sensor 20 made of a piezoelectric element is deformed as if it were expanded and contracted, and thus generates, for example, a negative voltage.

As described above, by using the piezoelectric element as the pressure sensor 20, it is possible to detect the vertical force and the horizontal force (rotating circumferential direction and radial direction) acting on the wafer W.

When the polished wafer W has attained a desired polishing state, the signal detected from the pressure sensor 20 changes from its previous value and then shows a constant value. Then, when this value is stabilized, it is considered that a desired polishing state has been obtained, and polishing of the wafer W is completed.

For example, a case where two types of wafers W1 and W2 having the structures shown in FIGS. 5A1 and 5B1 are polished will be described. Wafer W1 shown in FIG.
Is to be polished so that Cu is buried in the groove of the SiO2 layer. In this case, the polishing end point is to polish the Cu layer so that the barrier metal layer is exposed on the surface, Are flattened. On the other hand, the wafer W2 shown in FIG. 5B1 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.
FIGS. 5A2 and 5B2 show the pressure sensor 20 at this time.
Is an output value from the calculation unit based on the signal of Wafer W
In FIG. 1, the Cu layer to be polished is gradually flattened to increase the contact area with the polishing pad 102, so that the frictional force increases. Therefore, as shown in FIG. 5 (a2), the value of the output signal at this time is Gradually rise. 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, as shown in FIGS. 5 (b1) and 5 (b2), the polishing is further performed from the time point h1 when the oxide film is flattened, and the polishing is terminated at the time point h2 when the maximum value of the output signal is stabilized for a certain time.

As described above, by detecting the polishing end point of the wafer W by installing the pressure sensor 20 at the connection portion between the spindle 1 and the wafer holding head 50, even when a plurality of wafer holding heads 50 are provided, each The force acting on the wafer W held by the holding head 50 can be observed. Therefore, stable polishing end point detection can be performed by the individual wafer holding heads 50 without causing a wafer W in an over-polished state or a polished state. The pressure sensor 20 is connected to the spindle 1
Since it is installed on the side, it is not necessary to install the pressure sensor 20 in each wafer holding head 50, and the number of sensors to be used can be suppressed.

By using a piezoelectric element for the pressure sensor 20, a decrease in the rigidity of the device can be minimized. Further, the force acting on the wafer W can be detected by the shear force acting on the piezoelectric element, and even a slight change in polishing resistance can be reliably observed.

Then, the pressure sensor 20 is connected to the shaft portion 59.
A plurality of circumferentially arranged flanges 18b, which are contact portions between the upper end surface and the spindle-side connecting portion 4, allow the shear force in the circumferential direction and the radial direction to be measured by one of the pressure sensors 20. It can be detected reliably. The pressure sensor 20 can be disposed on a contact surface between a lower end surface of the shaft main body 1a and a spacer 21 provided integrally on the upper portion of the position adjusting member 18. That is, a plurality of pressure sensors 20 can be installed on the upper end surface of the spacer 21 in the circumferential direction, or can be installed on the lower end surface of the shaft main body 1a.

As a height adjusting mechanism of the wafer holding head 50, a position adjusting male screw portion 6 outside the bearing support portion 5, and screwed to the position adjusting male screw portion 6 and provided in the carousel 2. And a handle support portion 9 fixed to the bearing support portion 5 for rotating the bearing support portion 5 and having an adjusting handle 8. By rotating the bearing support 5 together with the handle support 9, the spindle 1
Is to be moved up and down. for that reason,
The fine adjustment of the position of the wafer holding head 50 can be easily performed, and the fine adjustment of the pressing force between the wafer W and the polishing pad 102 can be performed. Can be adjusted, and the polishing of all the wafers W can be performed stably.

Although the height adjustment is manually performed by the adjustment handle 8, it is of course possible to automatically perform the height adjustment using various actuators such as a servomotor.

The provision of the torque transmitting section 70 allows the wafer holding head 50 having a floating structure to be provided.
Even if is rotated, the action of excessive force acting on the diaphragm 55 in the torsional direction can be reduced, and the diaphragm 55 can be prevented from being damaged while maintaining the floating effect.

It should be noted that this torque transmitting portion 70 is
6 can be provided not only on the upper surface but also above the retainer ring 57 like the second torque transmitting portion 70 'in FIG. Such a torque transmitting unit 70 '
Is provided on the upper surface of the retainer ring 57 via the diaphragm 55, so that the rotational force of the spindle 1 can be transmitted to the carrier 56 and the retainer ring 57 while further reducing the torsional force acting on the diaphragm 55.

Instead of forming the diaphragm 55 by rubber, it is also possible to use a metal film of iron or the like having such an elasticity that the floating effect is not lost. By using a metal film for the diaphragm 55, its strength is increased, and even if the wafer holding head 50 is rotated at a high speed, damage to the diaphragm 55 can be prevented.

[0067]

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, since the sensor is provided at the connecting portion between the spindle and the wafer holding head, even when a plurality of wafer holding heads are provided, each sensor is held by each wafer holding head. The force acting on the wafer can be observed. Therefore, stable polishing end point detection can be performed without causing a wafer in an over-polished state or a poorly polished state. Also,
Since the sensors are provided on the spindle side, there is no need to install the sensors in each wafer holding head, and the number of sensors to be used can be reduced.

According to the second aspect of the present invention, the spindle and the wafer holding head are stably connected by screwing the female screw portion and the male screw portion formed respectively. Then, by disposing the sensor at a portion which is in contact with the upper end surface of the shaft portion, the force acting on the wafer is reliably observed by the sensor via the wafer holding head.

According to the third aspect of the present invention, the position adjusting member is provided between the spindle and the wafer holding head, and the thickness of the spacer portion of the position adjusting member is changed to be connected to the spindle. The position of the wafer holding head can be adjusted. And, by disposing the sensor at the portion where the lower end surface of the spindle shaft body and the position adjusting member abut, the force acting on the wafer can be reliably observed by the sensor via the wafer holding head.

According to the fourth aspect of the present invention, by using the piezoelectric element for the sensor, the vertical force and the shear force acting on the wafer can be observed, and the rigidity of the apparatus can be reduced. Reduction can be minimized.

According to the fifth aspect of the invention, even when a plurality of wafer holding heads are installed, polishing can be performed while reliably observing the forces acting on each wafer. Therefore, it is possible to prevent the production of a wafer in an over-polished state or an insufficiently polished state, and to realize efficient production of a wafer.

[Brief description of the drawings]

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

FIG. 2 is a cross-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. 3 is a diagram illustrating an arrangement of a pressure sensor provided on a spindle.

FIG. 4 is a diagram illustrating a torque transmission unit.

FIG. 5 is a cross-sectional view showing a layer configuration of a wafer and a view for explaining an output result of a sensor when the wafer is polished.

FIG. 6 is a diagram illustrating the entire wafer polishing apparatus.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Spindle 1a Shaft main body 1b Pipe line 2 Carousel 3 First bearing 4 Spindle side connection part 5 Bearing support part 6 Position adjustment external thread part 7 Adjustment handle 9 Handle support part 10 Fluid supply port 13 Position adjustment internal thread part 16 Spindle Housing 18 Position adjusting member 18a Projection 18b Flange 19 Head female thread 20 Pressure sensor 50 Wafer holding head 52 Head body 53 Top plate 54 Peripheral wall 55 Diaphragm 56 Carrier 57 Retaining ring 58 Head mounting screw 59 Shaft section 70 Torque transmission section 102 Polishing pad 103 Platen W Wafer

Claims (5)

[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 a relative movement of the wafer holding head, wherein the wafer holding head is horizontally rotatably supported by a spindle connected to an upper part thereof, and the wafer holding head of the spindle And a sensor for observing a force acting on the wafer at the time of polishing is provided on one surface of a portion connected to the wafer. 2. The wafer polishing apparatus according to claim 1, wherein the wafer holding head includes a columnar shaft portion provided on an upper portion thereof and having a thread portion on an outer peripheral surface, and the spindle includes: A cylindrical outer cylinder portion that opens downward, a female thread portion formed on the inner peripheral surface of the outer cylinder portion to be screwed with the male thread portion, and the male screw provided inside the outer cylinder portion; And an abutting surface arranged at a position where it abuts on the upper end surface of the shaft portion when the portion and the female screw portion are screwed. The sensor has a gap in a circumferential direction of the abutting surface. A plurality of wafer polishing apparatuses. 3. The wafer polishing apparatus according to claim 1, wherein the wafer holding head includes a columnar shaft part provided on an upper part thereof and having a thread part on an outer peripheral surface, and the spindle comprises: A cylindrical outer cylinder portion that is connected to a lower portion of the spindle shaft main body and that opens downward; a female thread portion formed on an inner peripheral surface of the outer cylinder portion to be screwed with the male thread portion; A position adjusting member that is provided inside the portion and has one surface abutting on the lower end surface of the shaft main body and the other surface abutting on the upper end surface of the shaft portion when the male screw portion and the female screw portion are screwed. And a plurality of the sensors are arranged at intervals in a circumferential direction of a contact surface between the lower end surface of the shaft main body and a position adjusting member. 4. The wafer polishing apparatus according to claim 1, wherein the sensor comprises a piezoelectric element. 5. A polishing apparatus comprising: a platen having a polishing pad adhered 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 polishing step of polishing the wafer with the polishing pad by relative movement of the wafer holding head, wherein an upper portion of the wafer holding head is horizontally rotatably supported by a spindle, and the wafer holding head of the spindle A sensor for observing a force acting on the wafer at the time of polishing on one surface of a portion connected to the wafer, and performing polishing while detecting a polishing state of the wafer based on an observation result of the sensor. Production method.