JP2001353658A - Wafer polishing apparatus and polishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wafer polishing apparatus and a polishing method capable of controlling a distribution of a polishing amount on a wafer surface. SOLUTION: On a carrier 23 holding a wafer, a plurality of heaters 26 (heating means) for independently heating the carrier 23 for each part, and a temperature sensor 27 for sensing the temperature of each part heated by the heater 26 ( A temperature detecting means), a polishing condition setting device for setting polishing conditions, and a control device for controlling the operation of each heater 26. The controller calculates the polishing performance when the wafer is polished under the polishing conditions set in the polishing condition setting device using the carrier 23, and the carrier 23 is suitable for polishing the wafer based on the polishing performance information. The temperature distribution of the carrier 23 when thermally deforming into a shape is calculated, and the heating of the carrier 23 by the heater 26 is controlled based on information on the temperature distribution and a signal sent from the temperature sensor 27.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus and a method for mirror-polishing a wafer surface such as a semiconductor wafer with high precision.

[0002]

2. Description of the Related Art In recent years, patterns have been increasingly miniaturized with the increase in the degree of integration of semiconductor manufacturing equipment. In particular, in order to easily and surely form fine patterns having a multilayer structure, the semiconductor wafer itself on which the patterns are formed Needless to say, it is becoming important to make the surface of the semiconductor wafer as flat as possible during the pattern formation process. As a polishing method for flattening the surface of these semiconductor wafers (hereinafter simply referred to as wafers), a chemical mechanical polishing method (CMP method) having a high degree of finished flatness has been spotlighted.

The CMP method includes SiO2, CeO2,
This is a method of chemically and mechanically polishing and flattening the wafer surface using a slurry mixed with an abrasive such as Al2O3. As a polishing apparatus for a wafer surface employing the CMP method, for example, a polishing apparatus shown in FIG. 9A is known.

In this wafer polishing apparatus, a disk-shaped rotary table (platen) 2 attached to a central shaft 1, a polishing pad 3 made of hard urethane or the like provided on the platen 2, and eccentric from the central shaft 1. A wafer holding head 4 which is opposed to the polishing pad 3 at the set position and is driven to rotate by a head driving mechanism (not shown); And a conditioner 5 for dressing the surface of the polishing pad 3.

A wafer holding head (hereinafter, simply referred to as a holding head) 4 has a disk shape smaller in diameter than the polishing pad 3, and is held by an arm (not shown) at an upper end of a rotating shaft 4 a thereof. It can approach and separate.
Therefore, the wafer W can be brought into contact with the polishing pad 3 while holding the wafer W on a carrier (not shown) provided below the holding head 4 (head end portion), and the wafer W can be carried in and out of the polishing pad 3. It can be carried out.

At the time of polishing the wafer W, the abrasive is supplied onto the polishing pad 3 as a liquid slurry S, flows between the wafer W held by the holding head 4 and the polishing pad 3, and Since the wafer W held by the wafer 4 rotates and the polishing pad 3 rotates about the central axis 1 at the same time, the lower surface of the wafer W is polished.

The conditioner 5 includes an arm 7 having a base fixed to a rotating shaft 6 provided outside the platen 2.
A state supported by the free end of the arm 7 and driven to rotate by a driving device (not shown) in contact with the surface of the polishing pad 3, or a state in which rotation is allowed by a frictional force received from the polishing pad 3. And a dresser 8 provided in the main body. Then, the surface of the polishing pad 3 is dressed by the rotation of the arm 7 and the rotation of the dresser 8.

When polishing a wafer, polishing conditions such as the number of rotations of the platen 2 and the holding head 4 and the polishing pressure are set so that the amount of polishing is uniform at any position on the surface of the wafer W. is necessary. Here, the polishing amount of the wafer W is proportional to the relative speed between the wafer W and the polishing pad 3 and the polishing pressure. In general, it is desirable that the holding head 4 can apply a uniform polishing pressure (contact pressure to the polishing pad 3) at any position on the surface of the wafer W. As a holding head for that purpose, for example, The floating type holding head shown in FIG. 9B is used.

This holding head comprises a head body 9 comprising a top plate and a cylindrical peripheral wall, and a diaphragm (a disk-shaped or ring-shaped fiber reinforced rubber film) stretched in the head body substantially perpendicularly to the head axis. 10), a disk-shaped carrier 11 made of a highly rigid material such as ceramic fixed to the lower surface of the diaphragm 10, and a circle fixed to the lower surface of the diaphragm 10 between the carrier 11 and the peripheral wall of the head body 9. It comprises an annular retainer ring 12. The carrier 11 and the retainer ring 12 are
Can be moved in the head axis direction by the elastic deformation of the head.

A shaft portion 13 provided on a top plate portion of the head body 9 and screwed to a spindle of the arm has a flow path 1
3a is formed in the vertical direction, and a fluid chamber 9a is formed above the diaphragm 10 of the head main body 9. Then, a fluid such as air is supplied from the flow path 13a to the fluid chamber 9a.
Is supplied in an adjustable manner. Therefore, the internal pressure of the fluid chamber 9a,
That is, the displacement force in the head axis direction of the carrier 11 displaced together with the diaphragm 10 can be adjusted, and the wafer W held on the carrier 11 via a sponge-like back pad P called an insert is applied to the polishing pad 3. The abutment pressure can be adjusted to an optimal one.

[0011]

In the conventional wafer polishing apparatus, even if the entire surface of the wafer is brought into contact with the polishing pad with a uniform pressure, the entire surface of the wafer cannot always be polished uniformly. Absent. This is because, for example, the wafer is polished by being brought into contact with the polishing pad while being rotated by the holding head, but depending on the polishing conditions, the relative speed with respect to the polishing pad on the inner peripheral side and the outer peripheral side of the wafer is different. Since they are different, a difference occurs in the amount of polishing between the inner peripheral side and the outer peripheral side. Further, depending on the polishing conditions, the slurry may be less likely to flow around the inner periphery of the wafer than the outer periphery, and in this case, a difference occurs in the polishing amount between the inner periphery and the outer periphery of the wafer.

Further, even when polishing is performed under polishing conditions aimed at achieving a high uniformity of the polishing amount, desired uniformity cannot always be obtained because of the influence of thermal deformation of the carrier. For example, thermal deformation of the carrier causes distortion of the wafer supporting surface of the carrier, so that a difference occurs in the pressure in contact with the polishing pad on the surface of the wafer, resulting in a difference in the amount of polishing at each portion of the wafer. In addition, in polishing a wafer in a production process or the like, polishing conditions for obtaining a desired polishing uniformity at each position on a wafer surface are limited due to a restriction on a production plan such as a problem of procuring secondary materials such as throughput and slurry. Not always possible. In reality, due to these restrictions, polishing may be performed under conditions where sufficient polishing performance cannot be obtained, and the result may be insufficient. Also, in the production process, for example, there is a demand for increasing the polishing amount of the outer peripheral portion of the wafer due to restrictions due to other processes, and the polishing of the wafer does not always require a constant polishing amount in the surface. .
In view of such circumstances, an apparatus as disclosed in Japanese Patent Publication No. 7-8472 has been devised as an apparatus for polishing the surface of a workpiece. This apparatus polishes a workpiece in the same manner as a wafer polishing apparatus. A rotary carrier for holding a workpiece is made of at least two materials having different coefficients of thermal expansion. It is characterized by having a temperature adjusting means for adjusting the temperature. The rotary carrier acts like a bimetal, and the radius of the rotary carrier is controlled by adjusting the temperature of the rotary carrier by temperature adjusting means. The apparatus controls the pressure of pressing the workpiece surface against the polishing pad by applying a concave bias or a convex bias to the workpiece mounted on the rotary carrier by controlling the shape of the rotary carrier in this way, The distribution of the polishing amount in the radial direction of the workpiece is controlled. However, in this device, the deformation of the rotary carrier occurs uniformly as a whole, and the degree of bending as a whole can be controlled, but the shape of the curved shape is not controlled. Therefore, the degree of freedom in adjusting the distribution of the polishing amount was low.

An object of the present invention is to provide a wafer polishing apparatus and a polishing method capable of controlling a distribution of a polishing amount on a wafer surface.

[0014]

In the wafer polishing apparatus according to the first aspect of the present invention, one surface of the wafer is brought into contact with a polishing pad stuck on a platen, and these are moved relatively to each other. A polishing apparatus for polishing, a carrier holding the wafer, a plurality of heating means for independently heating the carrier for each part, and sensing a temperature of each part of the carrier heated by the heating means. Temperature detecting means, polishing condition setting means for setting polishing conditions, and control means for controlling the operation of each heating means, wherein the control means sets the polishing conditions on the wafer using the carrier. Calculate the polishing performance when polishing under the polishing conditions set by the means,
Based on the information on the polishing performance, the temperature distribution of the carrier when the carrier is thermally deformed into a shape suitable for polishing the wafer is calculated, and the information of the temperature distribution and the signal sent by the temperature detection unit are used. And controlling the heating of the carrier by each of the heating means. In the wafer polishing apparatus configured as described above, the polishing performance is calculated from the polishing conditions set by the polishing condition setting means by the control means, and the carrier is thermally deformed into a shape suitable for wafer polishing. A temperature distribution is calculated. Based on this information,
The operation of the heating means independently provided for each part of the carrier is controlled by the control means, and each part of the carrier is heated so as to have the calculated temperature distribution. Then, the wafer is polished while holding the wafer by a carrier thermally deformed to a predetermined shape, so that the wafer is polished in a state where the wafer is in contact with the polishing pad with an appropriate pressure distribution, and the polishing tendency of the wafer is reduced. Will be corrected. Here, the polishing tendency of the wafer may be corrected, for example, so as to improve the uniformity of the surface of the wafer, or may be corrected so that the distribution of the polishing amount on the wafer surface becomes a desired distribution.

3. The polishing apparatus according to claim 2, wherein one surface of the wafer is brought into contact with a polishing pad stuck on a platen, and the wafers are relatively moved to polish the wafer. A carrier for holding the wafer, a plurality of heating means for independently heating the carrier for each part, a temperature detection means for sensing the temperature of each part of the carrier heated by the heating means, and polishing conditions Polishing condition setting means to be set;
When the wafer is polished under various polishing conditions using the carrier, storage means for storing information on polishing performance for each polishing condition as a database, and control means for controlling the operation of each heating means are provided. The control unit reads information on polishing performance corresponding to the polishing condition set by the polishing condition setting unit from the storage unit, and based on the information on the polishing performance, adjusts the carrier for polishing the wafer. Calculating the temperature distribution of the carrier when thermally deforming the carrier into a deformed shape, and controlling the heating of the carrier by each of the heating means according to information on the temperature distribution and a signal sent by the temperature detection means. . In the wafer polishing apparatus configured as described above, the control unit does not directly calculate the polishing performance from the set polishing conditions, but refers to the polishing performance information for each polishing condition stored in the storage unit. Thus, information on the polishing performance corresponding to the set polishing conditions is obtained, and the heating of the carrier is controlled based on this information.

According to a third aspect of the present invention, there is provided a polishing apparatus for polishing a wafer by bringing one surface of the wafer into contact with a polishing pad stuck on a platen and relatively moving the wafer and the polishing pad. A heating method for independently heating each portion of the carrier, which is a member to be provided, a polishing method for polishing the wafer by controlling the thermal deformation of the carrier by controlling the heating means, Determine the polishing performance when the wafer is polished under the set polishing conditions using the carrier, calculate the temperature distribution of the carrier when thermally deforming the carrier into a shape suitable for polishing the wafer,
The heating of the carrier by each of the heating means is controlled based on the information on the temperature distribution and the information on the temperature of each part of the carrier. In the wafer polishing method configured as described above, the temperature distribution of the carrier when the carrier is thermally deformed into an optimal shape for polishing the wafer is calculated based on the polishing performance information corresponding to the set polishing conditions. . The heating of each part of the carrier is controlled based on this information, and the carrier is heated so as to have the calculated temperature distribution. Then, the wafer is polished while holding the wafer by a carrier thermally deformed into a predetermined shape, so that the wafer is polished in a state where the wafer is in contact with the polishing pad with an appropriate pressure distribution, and the polishing tendency of the wafer is corrected. You. here,
The polishing tendency of the wafer may be corrected, for example, so as to improve the uniformity of the surface of the wafer, or may be corrected so that the distribution of the polishing amount on the wafer surface becomes a desired distribution.

[0017]

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

This wafer polishing apparatus has the same basic structure as that shown in FIG. 9 (1) described as a conventional example, including a platen (2), a polishing pad (3), a wafer holding head (4) and the like. The feature of the present invention is that the carrier constituting the wafer holding head is provided with a heating means such as a plurality of heaters and a plurality of temperature sensors (temperature detecting means) built-in or in contact with each other, thereby reducing the thermal deformation of each part of the carrier. By controlling, the distribution of the pressing pressure of the wafer by the carrier (the distribution of the polishing pressure) can be controlled to correct the polishing tendency of the wafer W. Therefore, a detailed description of the basic configuration is omitted to avoid duplication.

The wafer holding head may be of a gimbal type or the like. Here, an example in which the present invention is applied to a floating type wafer holding head will be described with reference to FIG.

The basic structure of this wafer holding head is the same as that shown in FIG. 9 (2) described as a conventional example. That is, the head main body 2 including the top plate portion and the cylindrical peripheral wall portion
And a diaphragm 22 made of a ring-shaped fiber reinforced rubber film stretched substantially perpendicularly to the head axis in the head body.
A disk-shaped carrier 23 made of a highly rigid material such as ceramic fixed to the lower surface of the diaphragm 22; and an annular ring fixed to the lower surface of the diaphragm 22 between the carrier 23 and the peripheral wall of the head body 21. Retaining ring 24
It is composed of

A flow path 25a is formed in the shaft portion 25 provided on the top plate of the head main body 21 in a vertical direction, and a fluid chamber 21a is formed above the diaphragm 22 of the head main body 21. ing. A fluid such as air is supplied to the fluid chamber 21a from the flow path 25a in an adjustable manner.

The present invention further provides a plurality of heaters 26 and a plurality of temperature sensors (temperature detecting means) 27 on the carrier 23.
The temperature of each part of the carrier 23 is controlled by controlling the operation of each heater 26 by controlling the operation of each heater 26 by controlling the control device C (by controlling the current and voltage supplied to the heater 26). The feature is that the thermal deformation of each part is controlled. In the drawing, a plurality of heaters 26 are embedded in the upper surface of the carrier 23, and the respective temperature sensors 27 are built in the heaters 26. In the present embodiment, as shown in FIGS. 1A and 1B, each heater 26 has an annular shape along the edge of the carrier 23 and a small disk shape occupying the center. Sensor 2
Numerals 7 are arranged at appropriate positions of the respective heaters 26. As shown in FIG. 1 (3), one temperature sensor 27 may be arranged for each heater 26. FIG.
As shown in (4), a plurality of heaters 26 may be provided concentrically, and one or more temperature sensors 27 may be provided for each heater 26. In addition, what is indicated by reference numeral P is a sponge-shaped back pad interposed when the wafer W is held on the carrier 23. Here, instead of embedding the heater 26 and the temperature sensor 27 in the upper surface of the carrier 23,
An opening is formed at a position facing at least a portion where the heater 26 and the temperature sensor 27 are installed on the upper surface of the carrier 3, and the heater 26 and the temperature sensor 27 are arranged in contact with the upper surface of the carrier 23 through the opening. Good. Here, as shown in FIG. 2, the control device C includes a polishing condition setting device (not shown) for setting polishing conditions, and a carrier 23.
Is connected to a memory (storage means) B for storing, as a database, information on the polishing performance for each polishing condition when the wafer W is polished under various polishing conditions using the control device C. From the setting device, the polishing conditions,
From the memory B, information on the polishing performance corresponding to the polishing conditions is received. The control device C controls the heater 2 based on the polishing performance information and the signal received from the temperature sensor 27.
6 is controlled.

Hereinafter, control of thermal deformation of each portion of the carrier 23, which is important in wafer polishing according to the present invention, will be described.

First, the thermal deformation of the carrier 23 and the tendency of the wafer W to be polished due to the shape of the carrier 23 will be described. The carrier 23 receives the heat generated during polishing of the wafer on the side where the wafer holding surface (lower surface) is formed, and emits the heat of the carrier 23 to the periphery on the other side. A thermal gradient occurs. Further, in the carrier 23, the outer peripheral portion is more likely to release heat to the outside than the inner peripheral portion where heat is stored.
The carrier 23 tends to have a thermal gradient also in the radial direction. As a result of the occurrence of the thermal gradient in the carrier 23, a difference occurs in the amount of thermal expansion between the high temperature side and the low temperature side of the carrier 23,
The carrier 23 is warped (thermally deformed). For this reason, a difference in pressure (polishing pressure) at which the carrier 23 presses the wafer W mainly occurs in the radial direction of the wafer W, and a difference in polishing amount occurs in the wafer W in the radial direction.

Next, the polishing tendency of the wafer W according to the polishing conditions will be described. The wafer W is polished by being brought into contact with the polishing pad 3 while being rotated by the holding head 4.
Since the relative speed with respect to the polishing pad 3 is different between the inner circumference side and the outer circumference side, a difference occurs in the polishing amount between the inner circumference side and the outer circumference side.
Further, depending on the polishing conditions, the slurry may be less likely to flow around the inner periphery of the wafer W than the outer periphery, and in this case, the polishing amount is different between the inner periphery and the outer periphery of the wafer W.

As described above, since the difference in the amount of polishing of the wafer W occurs mainly in the radial direction, the carrier 23 is
It is preferable that the pressure (polishing pressure) for pressing the carrier can be adjusted in the radial direction of the carrier 23. In the wafer polishing apparatus of the present invention, the distribution of the polishing pressure of the wafer W by the carrier 23 is adjusted by controlling the thermal deformation of the carrier 23. That is, the deformation of the carrier 23 is controlled by generating a heat gradient in the carrier 23 by using the heating by the heater 26 or the heat radiation of the carrier 23 itself (depending on the polishing tendency, heating may be performed to suppress the heat gradient). By adjusting the shape of the wafer support surface (lower surface) of the carrier 23 in this manner, the carrier 23
Adjusts the distribution of the pressure (polishing pressure) for pressing the wafer W against the polishing pad 3.

In the wafer polishing apparatus according to the present embodiment, the carrier 23 is provided by a plurality of heaters 26 which are arranged concentrically on the upper surface of the carrier 23 with or without spacing (hereinafter simply referred to as concentric). By heating each part to an appropriate temperature, thermal deformation of the carrier 23 (mainly, warpage in the thickness direction of the carrier 23) is controlled, and the wafer supporting surface can be adjusted so as to have an appropriate shape according to polishing performance. I have. Here, the shape of the wafer support surface is not necessarily required to be flat, but may be an arbitrary curved surface shape depending on the polishing amount of each part of the wafer W.

An example of polishing a wafer W by the wafer polishing apparatus of the present invention will be described below with reference to the graph of FIG. Here, the horizontal axis of each graph in FIG. 3 is the distance from the center of the wafer, and the vertical axis is FIGS. 3 (1), (2), and (3).
, The polishing amount of the wafer, the polishing pressure, and the polishing amount.
First, the correction of the polishing tendency due to the polishing conditions will be described. The graph in FIG. 3A shows the tendency of the wafer W to be polished (radial polishing) when the wafer is polished under certain polishing conditions while the polishing pressure is made substantially uniform over the entire surface of the wafer W. Amount distribution). Under these polishing conditions, although the polishing pressure is almost uniform over the entire surface of the wafer W,
Factors other than the thermal deformation of the carrier affect, and the polishing amount on the wafer surface is not uniform. Specifically, the polishing amount on the outer peripheral side is larger than the polishing amount on the inner peripheral side of the wafer W. These pieces of information are stored in the database of the memory B as information on the polishing performance.

In the wafer polishing apparatus of the present invention, the distribution of the polishing amount of the wafer W is corrected by controlling the thermal deformation of the carrier 23 and changing the distribution of the polishing pressure in the wafer surface. That is, by controlling the thermal deformation of the carrier 23,
The distribution of the polishing pressure of the wafer W derived from the shape of the carrier 23 is set as the distribution shown in the graph of FIG.
Specifically, the carrier 23 is warped so that the inner peripheral side protrudes toward the lower surface relative to the outer peripheral side. By doing so, the polishing amount on the inner peripheral side of the wafer W is made larger than the polishing amount on the outer peripheral side. Then, the wafer polishing apparatus of the present invention thermally deforms the carrier 23 in this way and controls the polishing tendency derived from the shape of the carrier 23, thereby forming the carrier 23 as shown in FIG. The polishing tendency derived from the polishing conditions is canceled by the polishing tendency derived from the shape.

Next, the carrier 2 by the wafer polishing apparatus
The control of the thermal deformation of No. 3 will be described in detail. Control device C
Adjusts the thermal distribution of the carrier 23 by adjusting the temperature distribution of the carrier 23, and corrects the distribution of the polishing pressure of the wafer W. As shown in FIG. 2, the control device C reads out the polishing performance (including information on the polishing tendency) corresponding to the polishing conditions set by the polishing condition setting device (not shown) from the memory B, and transfers the carrier 23 to the wafer. A temperature distribution (target temperature distribution) of the carrier 23 when thermally deforming into a shape suitable for W polishing is calculated (S1). And career 2
The operation of the heater 26 is controlled so that 3 has a target temperature distribution. That is, the control device C calculates the target temperature range of each part of the carrier 23 heated by each heater 26 based on the information on the polishing performance corresponding to the set polishing conditions. Further, before and after this, the actual measured value of the temperature of each part of the carrier 23 is obtained from the signal emitted from each temperature sensor 27 (S2). Then, the data of the target temperature range and the measured value of the temperature of each part of the carrier 23 are compared with each other. If the measured value of each temperature sensor 27 is lower than the respective target temperature range, the power supply to each heater 26 is performed. Is performed, and if the actual value measured by each temperature sensor 27 is higher than each target temperature range, the power supply to each heater 26 is stopped, and the portion is cooled by the heat radiation of the carrier 23 itself (S3). Hereinafter, S
2. The processing of S3 is repeated.

In the example of FIG. 3A, the polishing tendency due to the polishing conditions is corrected by the polishing tendency due to the thermal deformation by lowering the polishing pressure on the outer peripheral side of the wafer W and increasing the polishing pressure on the inner peripheral side. can do. That is, since the warpage in the thickness direction of the carrier 23 (in the wafer supporting surface) in the downwardly convex direction may be increased, the controller C causes the heater 26 to heat the respective portions on the upper surface side of the carrier 23 to a predetermined temperature. To increase the warpage of the carrier 23. Furthermore,
Of the heaters 26, the temperature at which the carrier 23 is heated is adjusted independently by the heater 26 provided at the center of the carrier 23 and the heater 26 provided at the outer peripheral side, so that the degree of warpage of the carrier 23 is finely adjusted. . As described above, the pressure distribution applied to the wafer is adjusted by controlling the shape of the carrier 23, and the polishing of the wafer W is performed in a state where the polishing tendency derived from the polishing conditions and the polishing tendency derived from the shape of the carrier 23 are substantially symmetrical. By performing the above, the polishing tendency of the wafer W can be corrected, and the polishing amount can be made substantially uniform over the entire surface of the wafer W as shown by the solid line in the graph of FIG. Here, in the above example, the correction of the polishing tendency when the polishing amount on the outer peripheral side of the wafer W is larger than the polishing amount on the inner peripheral side has been described. There is also a polishing condition that tends to increase the polishing amount as compared with the polishing amount. In this case, by lowering the polishing pressure on the inner peripheral side of the wafer W and increasing the polishing pressure on the outer peripheral side, the polishing tendency derived from the polishing conditions can be corrected by the polishing tendency derived from thermal deformation. That is, since the warpage in the thickness direction of the carrier 23 (in the wafer supporting surface) in the downwardly convex direction may be suppressed, the controller C causes the heater 26 to heat the respective portions on the upper surface side of the carrier 23 at a predetermined temperature. Heat it up
The warpage of the carrier 23 is suppressed.

Next, correction of the polishing tendency due to the shape (thermal deformation) of the carrier 23 when using the polishing conditions for making the wafer W uniform over the entire surface when there is no thermal deformation of the carrier 23 will be described. I do. In this case,
In the same manner as the correction of the polishing tendency derived from the polishing conditions described above,
The control device C adjusts the warpage of the carrier 23 so that the pressure at which the carrier 23 presses the wafer W is uniform over the entire surface of the wafer W. Thus, the polishing tendency derived from the shape of the carrier 23 is corrected, and the wafer W
The polishing amount can be made substantially uniform over the entire surface (see FIG. 4).

The correction of the polishing tendency as described above is not limited only to the start of polishing, but also takes into account fluctuations in polishing conditions (for example, fluctuations in the amount of slurry supplied) and progress of thermal deformation of the carrier 23 during polishing. By doing so, it can be performed at any time during the polishing operation.

In order to correct such polishing tendency, it is necessary to provide information on polishing performance corresponding to each polishing condition and temperature distribution of a carrier suitable for this polishing performance. This information may be directly calculated by the control device C from the polishing conditions set by the polishing condition setting device. However, information previously obtained by a method such as actual measurement or numerical calculation is stored in the memory B.
May be stored as a database, and the control device C may read out this information from the memory B and use it for controlling the heater 26. In creating this database, various data including the data shown in FIG. 3 and the data shown in FIGS. 7 and 8 are considered.

Here, the relationship between the temperature distribution of each part of the carrier 23 and the thermal deformation of the carrier 23 can be examined as follows. Here, the carrier 23 is actually
The test is performed using a carrier 23a having the same shape and material as the carrier 23 instead of using the carrier 23a. FIG.
Temperature measurement position on the carrier 23a, ie, carrier 2
The distance from the center of the carrier and the distance from the bottom surface of the temperature sensor 34 embedded in 3a are shown, and reference numerals a, b, and c in the figure correspond to those in FIGS.
FIG. 6 is a schematic view of an apparatus for heating the carrier 23a and measuring the temperature distribution thereof. The support section 31 includes a heater, the mounting table 32 fixed on the support section 31 and heated by the heater. A pressing body 33 for pressing down the center of the carrier 23a mounted together with the wafer W on the mounting table 32 so as not to move, and a temperature sensor 3 embedded in a temperature measuring position of the carrier 23a.
4, a pickup gauge 35 for detecting the position of the upper surface of the mounting table 32, and a micrometer 36 for measuring the displacement in the thickness direction of the carrier 23a mounted on the mounting table 32 ( Further, a micrometer for measuring the radial displacement of the carrier 23a may be provided).
The signal from the temperature sensor 34 is recorded in the data logger 37 together with information on the displacement of each part of the carrier 23a.
FIG. 7 is a diagram showing a measurement result by this device, (measured value of micrometer 36)-(pickup gauge 35).
Is 13 μm. FIG. 8 is a diagram showing a temperature distribution of the carrier 23a before and during polishing. As can be seen from FIGS. 7 and 8, the portion closer to the center of the carrier 23a during heating and polishing also reduces
It can be seen that the temperature near the lower surface of a becomes higher. By changing the heating conditions of the carrier 23a in various ways,
The relationship between the temperature distribution of each part of the carrier 23a (carrier 23) and the thermal deformation is obtained by actual measurement.

The relationship between the temperature distribution of each part of the carrier 23a (carrier 23) and the thermal deformation may be obtained by using a numerical analysis method other than the above-mentioned method, for example, a finite element method. When such a relationship is calculated by numerical analysis, it is also possible to calculate the deformation distribution of the carrier when a complicated temperature distribution that cannot be measured by actual measurement occurs in the carrier.

[0037]

According to the wafer polishing apparatus according to the first aspect of the present invention, the pressure distribution for bringing the wafer into contact with the polishing pad can be adjusted, whereby the polishing conditions and the thermal deformation of the carrier can be adjusted. The polishing tendency can be corrected, and the distribution of the polishing amount on the wafer surface can be controlled. Further, since the amount of deformation can be controlled for each part of the carrier, the degree of freedom in controlling the distribution of the amount of polishing can be increased. By controlling the distribution of the polishing amount on the wafer surface in this way, for example, the uniformity of the surface of the wafer can be improved or the wafer surface can have a desired polishing amount distribution.

According to the wafer polishing apparatus of the present invention, the control means does not directly calculate the polishing performance from the set polishing conditions, but refers to the information on the polishing performance for each polishing condition obtained in advance. Therefore, even when the polishing conditions are changed, the polishing can be started quickly. In addition, since the control means does not need to have a higher calculation capability than when directly calculating the polishing performance, the wafer polishing apparatus of the present invention can be realized at low cost.

According to the wafer polishing method of the present invention, the pressure distribution at which the wafer is brought into contact with the polishing pad can be adjusted, thereby reducing the polishing tendency of the wafer due to the polishing conditions and the thermal deformation of the carrier. By making corrections, the distribution of the polishing amount on the wafer surface can be controlled. Further, by controlling the amount of deformation for each part of the carrier, the degree of freedom in controlling the distribution of the amount of polishing can be increased. By controlling the distribution of the polishing amount on the wafer surface in this way, for example, the uniformity of the surface of the wafer can be improved or the wafer surface can have a desired polishing amount distribution.

[Brief description of the drawings]

FIG. 1 is a view of a wafer holding head constituting a wafer polishing apparatus of the present invention, wherein (1) is a side sectional view of a floating system, and (2), (3) and (4) are heaters and temperature sensors, respectively. It is a top view which shows the example of arrangement | positioning on a carrier.

FIG. 2 is a schematic diagram of a mechanism for controlling heating of a carrier in the wafer polishing apparatus of the present invention.

FIG. 3 is a diagram showing the concept of a method of controlling the amount of polishing of a wafer according to the present invention, wherein the polishing tendency derived from polishing conditions other than thermal deformation of the carrier, the polishing tendency derived from the shape of the carrier, It is a graph which shows an association.

FIG. 4 is a diagram showing an example of a concept of a method of controlling a polishing amount of a wafer according to the present invention.

FIG. 5 is a diagram illustrating a method for measuring the temperature distribution of a carrier, and is a diagram illustrating a carrier temperature measurement position.

FIG. 6 is a schematic diagram of a measuring device for heating a carrier and measuring a temperature distribution.

FIG. 7 is a diagram showing a measurement result obtained by the measuring device shown in FIG. 6;

8 is a diagram showing a temperature distribution of a carrier before and during polishing obtained by the measuring device shown in FIG. 6;

FIG. 9 is a diagram of a conventional wafer polishing apparatus, and (1)
2 is an enlarged perspective view of a main part, and FIG. 2B is a side sectional view of a floating type wafer holding head constituting the apparatus.

[Explanation of symbols]

2 Platen 3 Polishing pad 23 Carrier 26 Heater (Heating means) 27 Temperature sensor (Temperature detecting means) B Memory (Storage means) C Controller W Wafer

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Toyohisa Kongoji 1-297 Kitabukuro-cho, Omiya-shi, Saitama Mitsubishi Materials Corporation Intelligent Equipment and Systems Development Center F-term (reference) 3C058 AB04 AC01 AC02 BA02 BA08 BB08 BB09 BC01 CB01 CB03 DA17

Claims (3)

[Claims] 1. A polishing apparatus for polishing a wafer by bringing one surface of the wafer into contact with a polishing pad stuck on a platen and relatively moving the wafer, the carrier holding the wafer, and the carrier A plurality of heating means for independently heating each part, a temperature detecting means for sensing a temperature of each part of the carrier heated by each of the heating means, a polishing condition setting means for setting a polishing condition, Control means for controlling the operation of each heating means, the control means calculates the polishing performance when the wafer is polished under the polishing conditions set by the polishing condition setting means using the carrier, Based on the polishing performance information, calculate the temperature distribution of the carrier when thermally deforming the carrier into a shape suitable for polishing the wafer, The signal sent by the temperature distribution information and said temperature detecting means, the wafer polishing apparatus characterized by controlling the heating of the carriers by the respective heating means. 2. A polishing apparatus for polishing the wafer by bringing one surface of the wafer into contact with a polishing pad stuck on a platen and relatively moving the wafer, the carrier holding the wafer, and the carrier A plurality of heating means for independently heating each part, a temperature detecting means for sensing a temperature of each part of the carrier heated by each of the heating means, a polishing condition setting means for setting a polishing condition, When the wafer is polished under various polishing conditions using a carrier, storage means for storing information on polishing performance for each polishing condition as a database, and control means for controlling the operation of each heating means The control means reads information on polishing performance corresponding to the polishing conditions set by the polishing condition setting means from the storage means; Based on the performance information, calculate the temperature distribution of the carrier when thermally deforming the carrier into a shape suitable for polishing the wafer, by the information of the temperature distribution and a signal sent by the temperature detecting means, A wafer polishing apparatus, wherein heating of the carrier by each heating means is controlled. 3. A polishing apparatus for polishing a wafer by bringing one surface of the wafer into contact with a polishing pad affixed on a platen and moving the wafer relative to each other, wherein each part of a carrier which is a member holding the wafer is provided. A heating means for independently heating the wafer, and a polishing method for polishing the wafer by controlling thermal deformation of the carrier by controlling the heating means, wherein the wafer is set using the carrier. Finding the polishing performance when polishing under the polishing conditions, calculating the temperature distribution of the carrier when thermally deforming the carrier into a shape suitable for polishing the wafer, the information of the temperature distribution and the respective parts of the carrier A wafer polishing method, wherein heating of the carrier by each of the heating means is controlled based on temperature information.