JP2002200552A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polishing device capable of carrying out polishing according to the distribution of the thickness of the film formed on the surface of the workpiece such as a semiconductor wafer and obtaining uniformity of the film thickness after polishing. SOLUTION: The polishing device for polishing a semiconductor wafer W, which is a workpiece, pressed against the polishing face of a polishing table 11 is provided with a dresser 39 for dressing the polishing face of the polishing table 11, a rocking motor 36 for moving the dresser 39 on the polishing face of the polishing table 11, a control device 50, which controls the speed of the motion of the dresser 39 caused by the rocking motor 36 according to the thickness of a film to be polished at a specified position in the region in the polishing face used for polishing a specified position in the polished face of the semiconductor wafer W.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing an object to be polished, such as a semiconductor wafer, in a flat and mirror-like manner, and more particularly to dressing a surface of a polishing cloth attached to an upper surface of a polishing table in the polishing apparatus. The present invention relates to a polishing apparatus having a dresser.

[0002]

2. Description of the Related Art In recent years, as the degree of integration of semiconductor devices has increased, circuit wiring has become finer, and the distance between wirings has become smaller. In particular, in the case of optical lithography with a line width of 0.5 μm or less, the depth of focus becomes shallow, so that the image plane of the stepper needs to be flat. One means for planarizing the surface of such a semiconductor wafer is chemical mechanical polishing (CMP).
Is known.

As shown in FIG. 12, a polishing apparatus of this type includes a polishing table 302 which forms a polishing surface by attaching a polishing cloth (polishing pad) 300 to an upper surface, and a substrate such as a semiconductor wafer to be polished. And a top ring 304 for holding W with its polished surface facing the polishing table 302. When the polishing process of the semiconductor wafer W is performed using such a polishing apparatus, the polishing table 302 and the top ring 304 are respectively rotated, and the polishing liquid nozzle 306 installed above the polishing table 302 is rotated.
The semiconductor wafer W is pressed against the polishing cloth 300 of the polishing table 302 by the top ring 304 at a constant pressure while supplying more abrasive liquid. The abrasive fluid supplied from the abrasive fluid nozzle 306 is, for example, a suspension in which abrasive grains composed of fine particles of silica or the like are suspended in an alkaline solution, and is a combination of chemical polishing action by alkali and mechanical polishing action by abrasive grains. The semiconductor wafer W is polished flat and mirror-like by chemical / mechanical polishing as an action.

When the semiconductor wafer W is brought into contact with the polishing cloth 300 and polishing is performed by rotating the polishing table 302, abrasive grains and polishing debris adhere to the polishing cloth 300, and the characteristics of the polishing cloth 300 change. As a result, polishing performance deteriorates. For this reason, when the polishing of the semiconductor wafer W is repeated using the same polishing cloth 300, there is a problem that the polishing rate decreases or polishing unevenness occurs. Therefore, conditioning called dressing for restoring the surface state of the polishing pad 300 before or after or during polishing of the semiconductor wafer is performed.

[0005] When dressing the polishing cloth,
A dresser 308 is provided in the polishing apparatus, and when the semiconductor wafer W to be polished is replaced, the dresser 308 is used.
The dressing of the polishing cloth 300 is performed. That is,
By pressing the dressing member attached to the lower surface of the dresser 308 against the polishing cloth 300 of the polishing table 302 and rotating the polishing table 302 and the dresser 308 respectively, abrasive grains and cutting chips attached to the polishing surface are removed. At the same time, the entire polished surface is flattened and dressed, and the polished surface is regenerated.

[0006]

By the way, the thin film formed on the surface of the semiconductor wafer has a different thickness at a position in the radial direction of the semiconductor wafer due to the characteristics of a method and an apparatus at the time of film formation. That is, it has a film thickness distribution in the radial direction. Also,
Such a film thickness distribution differs depending on a film forming method and a type of a film forming apparatus. In other words, the radial position and the number of the thick portion and the difference in the thickness between the thin portion and the thick portion differ depending on the method of forming the film and the type of the film forming apparatus.

However, in the conventional dresser described above, since the entire polishing surface is dressed uniformly, the entire polishing surface is reproduced in the same manner, and the entire polishing surface has the same polishing power. Therefore, when the polishing surface is regenerated with a conventional dresser and then the entire surface of the semiconductor wafer is uniformly pressed and polished, the polishing rate becomes constant over the entire surface of the semiconductor wafer. For this reason, it is not possible to perform polishing suitable for the above-described film thickness distribution, and overpolishing may occur in a portion having a small film thickness and insufficient polishing may occur in a portion having a large film thickness.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems of the prior art, and it is an object of the present invention to perform polishing in accordance with the film thickness distribution of a thin film formed on the surface of an object to be polished such as a semiconductor wafer. It is an object of the present invention to provide a polishing apparatus capable of obtaining a uniform film thickness after polishing.

[0009]

In order to solve the problems in the prior art, the present invention provides a polishing table having a polishing surface, and a top ring for pressing an object to be polished against the polishing surface of the polishing table. A polishing apparatus for pressing the object to be polished against the polishing surface of the polishing table to polish the object to be polished, comprising a dresser for sharpening the polished surface of the polishing table, wherein the dresser comprises: A region of the polishing surface used for polishing a predetermined position in the surface to be polished of the object is sharpened according to a film thickness to be polished at the predetermined position in the surface to be polished.

According to another aspect of the present invention, there is provided a polishing table having a polishing surface, and a top ring for pressing an object to be polished on the polishing surface of the polishing table, wherein the object to be polished is mounted on the polishing surface of the polishing table. A polishing apparatus for polishing the polishing object by pressing the dresser, a dresser for sharpening the polishing surface of the polishing table, a moving mechanism for moving the dresser on the polishing surface of the polishing table, and a rotation for rotating the dresser. At least one of a mechanism and a pressing mechanism for pressing the dresser against a polishing surface of the polishing table; and a polishing mechanism in a region of the polishing surface used for polishing a predetermined position of the polishing object in the surface to be polished. Depending on the film thickness to be polished at a predetermined position in the plane, the moving speed of the dresser by the moving mechanism and the moving speed of the dresser by the rotating mechanism Rotational speed of the dresser, characterized by comprising a control device for controlling at least one of the pressing load of the dresser by the pressing mechanism.

According to the present invention, the region to be dressed in the region of the polishing surface can be changed arbitrarily.
It is possible to dress and sharpen a polished surface used for polishing a portion having a large thickness to be polished than a polished surface used for polishing a portion having a small thickness to be polished. Thereby, a relatively thick portion having a large film thickness to be polished and a relatively small portion having a thin film thickness can be polished, and appropriate polishing in accordance with a profile (film thickness distribution) of a surface to be polished of an object to be polished can be performed. Becomes possible.

In one aspect of the present invention, the dresser is a dresser having a smaller diameter than the object to be polished. Further, the dresser sharpens the polished surface during polishing.
Furthermore, a washing tank for washing the dresser is provided.

According to another aspect of the present invention, there is provided a film thickness measuring device for measuring a film thickness to be polished on the surface to be polished of the object to be polished. With such a configuration, since the profile of the actual polished surface of the object to be polished measured by the film thickness measuring device is obtained, it is possible to perform more appropriate polishing according to the actual profile of each object to be polished. Become.

In another aspect of the present invention, the apparatus further comprises a second dresser for sharpening substantially the entire polishing surface against which the object to be polished is pressed. Preferably, the second dresser is a dresser having a diameter larger than that of the object to be polished, and substantially the entire polishing surface on which the object to be polished is pressed by the second dresser.
This makes it possible to planarize the polished surface by selectively removing the protrusions on the polished surface. That is, since the portion that has been sharpened by dressing during polishing is sharpened quickly, the surface of the polished surface after polishing has irregularities. However, by the dressing with the second dresser, only the protruding portion of the portion is reduced. Since it can be removed, the surface of the polished surface can be flattened.

Further, one aspect of the present invention is characterized in that the second dresser sharpens substantially the entire polished surface when the polished surface is locally worn. With such a configuration, for example, even when the polishing surface of the polishing table is locally depleted due to dressing by the other dresser, the state of the polishing surface can be reset by the second dresser. Can be more accurate.

According to another aspect of the present invention, there is provided a polishing table having a polishing surface, and a top ring for pressing the polishing object on the polishing surface of the polishing table. In a polishing apparatus for pressing and polishing an object to be polished, a first dresser for sharpening a polishing surface of the polishing table during polishing of the object to be polished, and a first dresser for polishing when the object to be polished is not polished. A dressing unit is provided which is integrated with a second dresser for sharpening the polishing surface of the polishing table. As a result, two dressers having different purposes can be integrated, and the space of the equipment can be reduced.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of a polishing apparatus according to the present invention will be described in detail with reference to FIGS. FIG. 1 is a plan view schematically showing a polishing apparatus according to the present embodiment.

As shown in FIG. 1, in the polishing apparatus according to the present invention, a pair of polishing portions 1a and 1b are disposed at one end of a space on a floor having a rectangular shape as a whole so as to face left and right. The semiconductor wafer storage cassette 2
A pair of load / unload units on which a and 2b are placed are arranged. On a line connecting the polishing units 1a and 1b and the load / unload unit, two transfer robots 4a and 4b for transferring a semiconductor wafer are arranged to form a transfer line. On both sides of the transport line, one reversing machine 5, 6 and two cleaning machines 7a, 7b, 8a, 8b are arranged with the reversing machines 5, 6 interposed therebetween.

The two polishing units 1a and 1b are provided with devices having basically the same specifications symmetrically arranged on a transport line, and each of them has a polishing table 11 having a polishing cloth adhered to its upper surface.
And a top ring unit 12 for holding a semiconductor wafer to be polished by vacuum suction and pressing the semiconductor wafer against a polishing table 11 for polishing, and a dressing unit 13 for dressing a polishing cloth on the polishing table 11. And In addition, the polishing units 1a and 1b include:
A pusher 14 for transferring a semiconductor wafer to and from the top ring unit 12 is provided on each transfer line side.

Each of the transfer robots 4a and 4b has an articulated arm that can freely bend in a horizontal plane, and uses two upper and lower grips as dry fingers and wet fingers. Since two robots are used in the present embodiment, basically, the first robot 4a is
The area closer to the cassettes 2a and 2b than the second robot 4 is
b is responsible for the regions on the polishing units 1a and 1b side from the reversing machines 5 and 6, respectively.

The reversing devices 5 and 6 are for reversing the semiconductor wafer upside down, and are arranged at positions where the hands of the transfer robots 4a and 4b can reach. In the present embodiment, the two reversing machines 5, 6 are selectively used for handling a dry substrate and for handling a wet substrate.

The type of each of the cleaning machines 7a, 7b, 8a and 8b is arbitrary. For example, the polishing sections 1a and 1b are cleaning machines 7a and 7b of a type in which the front and back surfaces of a semiconductor wafer are wiped with a sponge roller. On the cassette 2a, 2b side, there are cleaning machines 8a, 8b of a type in which the cleaning liquid is supplied while gripping the edge of the semiconductor wafer and rotating in a horizontal plane. The latter also has a function as a dryer for drying by centrifugal dehydration. The primary cleaning of the semiconductor wafer can be performed in the cleaning machines 7a and 7b, and the primary cleaning of the semiconductor wafer can be performed in the cleaning machines 8a and 8b.
Secondary cleaning of the semiconductor wafer after the next cleaning can be performed.

Next, details of the above-mentioned polishing section will be described.
FIG. 2 is a longitudinal sectional view schematically showing a main part of the polishing section 1a shown in FIG. 1, and FIGS. 3 and 4 are plan views schematically showing the polishing section 1a of FIG. In the following, only the polishing section 1a will be described, but the polishing section 1b can be considered in the same manner as the polishing section 1a.

As shown in FIG. 2, the surface of the polishing pad 10 of the polishing table 11 forms a polishing surface which is in sliding contact with the semiconductor wafer W to be polished. The polishing table 11 is connected to a motor (not shown) disposed below the polishing table 11 via a table shaft 11a, and the polishing table 11 is rotatable around the table shaft 11a.

As shown in FIGS. 2 to 4, a polishing liquid / water supply nozzle 15 is disposed above the polishing table 11, and a polishing liquid used for polishing is supplied from the polishing liquid / water supply nozzle 15. A dressing liquid (for example, water) used for dressing is supplied onto the polishing pad 10. A frame 17 for collecting the polishing liquid and the water is provided around the polishing table 11, and a gutter 17a is formed below the frame.

Above the polishing table 11, there is provided an atomizer 16 for spraying a liquid obtained by mixing nitrogen gas and pure water or a chemical solution onto the polishing surface of the polishing cloth. The atomizer 16 includes a plurality of injection nozzles 16a connected to a nitrogen gas supply source and a liquid supply source. Nitrogen gas from the nitrogen gas source and pure water or chemicals from the liquid source,
The pressure is adjusted to a predetermined pressure by a regulator or an air operator valve (not shown), and the two are mixed and supplied to the injection nozzle 16a of the atomizer 16 in a mixed state.

The mixed nitrogen gas and pure water or chemical solution are
The liquid is atomized from the injection nozzle 16a of the atomizer 16 toward the polishing cloth 10 in a state where the liquid is atomized, the liquid is solidified into fine particles, and the liquid is vaporized (these are referred to as atomized or atomized). You. Whether the mixed liquid is ejected in the state of atomization of liquid, solidification of fine particles, or gasification is determined by the pressure, temperature, nozzle shape, or the like of nitrogen gas and / or pure water or a chemical solution. Accordingly, the state of the liquid to be ejected can be changed by appropriately changing the pressure, temperature, nozzle shape, and the like of the nitrogen gas and / or pure water or the chemical liquid by a regulator or the like.

The top ring unit 12 includes a rotatable support shaft 20, a top ring head 21 connected to the upper end of the support shaft 20, a top ring shaft 22 hanging from a free end of the top ring head 21, A substantially disk-shaped top ring 2 connected to the lower end of the shaft 22
And 3. The top ring 23 is a support shaft 2
As the top ring head 21 is swung by the rotation of 0, the top ring head 21 moves in the horizontal direction, and reciprocating motion between the pusher 14 and the polishing position on the polishing pad 10 becomes possible as shown by an arrow A in FIG. I have.

The top ring 23 is connected via a top ring shaft 22 to a motor (not shown) provided inside the top ring head 21 and an elevating cylinder. It is rotatable. Further, the semiconductor wafer W to be polished is sucked and held on the lower end surface of the top ring 23 by vacuum or the like. With these mechanisms, the semiconductor wafer W held on the lower surface thereof can be pressed against the polishing pad 10 with an arbitrary pressure while the top ring 23 rotates.

The dressing unit 13 regenerates the surface of the polishing pad 10 which has been deteriorated by polishing, and is disposed on the opposite side of the center of the polishing table 11 from the top ring unit 12. As shown in FIGS. 2 to 4, the dressing unit 13 in the present embodiment includes:
Two dressers, a first dresser 39 and a second dresser
The dresser 33 is integrally provided. As will be described later, the first dresser 39 is used for dressing the polishing pad 10 during polishing, and the second dresser 33 is used for roughening for initial surface adjustment of the polishing pad 10 before polishing. .

The dressing unit 13 includes a rotatable support shaft 30, a dresser head 31 connected to an upper end of the support shaft 30, a dresser shaft 32 hanging from a free end of the dresser head 31, and a dresser shaft 32.
And a substantially disk-shaped second dresser 33 connected to a lower end of the second dresser. The second dresser 33 moves in the horizontal direction together with the swinging of the dresser head 31 due to the rotation of the support shaft 30, and the dressing position on the polishing pad 10 and the outside of the polishing table 11 as shown by the arrow B in FIGS. Reciprocating movement is possible with the standby position. Further, the second dresser 33 is connected via a dresser shaft 32 to a motor (not shown) provided inside the dresser head 31 and a lifting cylinder, whereby the second dresser 33 can be raised and lowered and rotatable around the dresser shaft 32. I have. Note that a dresser cleaning tank 1 for cleaning the second dresser 33 is provided at a standby position outside the polishing table 11.
8 are arranged.

Here, the second dresser 33 includes a pellet and ring type diamond dresser 34 as a dressing member. The diamond dresser 34 has a plurality of disk members on which a granular material such as diamond particles is electrodeposited on the periphery of the lower surface of the second dresser 33. The diameter of the second dresser 33 is, for example, 270 mm, which is larger than the diameter (200 mm) of the semiconductor wafer W to be polished. Therefore, the area of the polished surface dressed by the second dresser 33 is larger than the area of the polished surface used for polishing the semiconductor wafer W.

A support portion 3 is provided on the side of the dresser head 31.
5 is fixed, and a swing motor 36 is fixed to the tip of the support portion 35. A swing arm 37 is connected to a motor shaft 36 a of the swing motor 36, and the swing arm 37 swings by rotating the swing motor 36. The swing motor 36 is connected to a control device 50, and the control device 50 controls the motor speed (swing speed). Swing motor 36
Constitutes a moving mechanism for moving a first dresser 39 described later on the polishing surface of the polishing table 11.

A dresser shaft 38 hangs from the free end side of the swing arm 37, and the dresser shaft 3
A substantially disc-shaped first dresser 39 is connected to the lower end of 8. The first dresser 39 moves in the horizontal direction with the swing of the swing arm 37 driven by the swing motor 36,
As shown by an arrow C in FIG. 4, reciprocation is possible between a dressing position on the polishing pad 10 and a standby position outside the polishing table 11. A support base 46 is fixed below the dresser head 31 of the support shaft 30.
6 is provided with a tub-shaped dresser cleaning tank 47 for cleaning the first dresser 39 at a standby position of the first dresser 39. The support 46 swings integrally with the dresser head 31 by the rotation of the support shaft 30.

The dresser shaft 38 is attached to the swing arm 37.
The dresser shaft 38 can be moved up and down by the air cylinder (pressing mechanism) 40 fixed to the air cylinder 40. Further, the dresser shaft 38 is connected to the rotary cylinder 41 via a key (not shown). The rotary cylinder 41 has a timing pulley 42 on its outer peripheral portion. A rotation motor (rotation mechanism) 43 is fixed to the swing arm 37, and the timing pulley 42 is connected to a timing pulley 45 provided on the rotation motor 43 via a timing belt 44. Accordingly, by driving the rotary motor 43, the rotary cylinder 41 and the dresser shaft 38 rotate integrally via the timing pulley 45, the timing belt 44, and the timing pulley 42, and the first dresser 39 rotates.

Here, the first dresser 39 has a disk type diamond dresser 48 as a dressing member. This diamond dresser 48
Is a disk member on which a granular material such as diamond particles is electrodeposited on the entire lower surface of the first dresser 39. The diameter of the first dresser 39 is, for example, 100 mm, and the diameter of the semiconductor wafer W to be polished (200 mm).
mm). Therefore, the area of the polished surface dressed by the first dresser 39 is smaller than the area of the polished surface used for polishing the semiconductor wafer W.

As described above, the dressing unit in the present embodiment has a configuration in which two dressers having different purposes and a cleaning tank of one of the dressers are integrated. With such a configuration, it is possible to achieve space saving of the equipment.

Next, a description will be given of the operation when polishing and dressing of a semiconductor wafer are performed using the polishing apparatus having the above configuration. FIGS. 5 to 7 are timing charts showing a series of operations in the present embodiment.

First, the example shown in FIG. 5 will be described. First, an initial surface adjustment of the polishing cloth before polishing is performed. In the initial surface adjustment of the polishing cloth before polishing, roughening is performed by thinly shaving the surface of the polishing cloth 10 using the second dresser 33 of the dressing unit 13. FIG.
Indicates such a state. In this case, the support shaft 3
The rotation of 0 moves the dresser head 31 to the dressing position on the polishing pad 10. Then, while independently rotating the second dresser 33 and the polishing table 11, the diamond dresser 34 held by the second dresser 33 is brought into contact with the polishing cloth 10 at a predetermined pressure. At this time, water is supplied from the abrasive / water supply nozzle 15 to the upper surface of the polishing cloth 10 at the same time as or before the dressing member 34 comes into contact with the polishing cloth 10, and the remaining water is used in the polishing cloth 10. Wash off the used polishing liquid. As described above, the polishing surface of the polishing pad 10 is entirely regenerated by the second dresser 33.

Next, dressing by the second dresser 33 before polishing is performed. During the dressing by the second dresser 33 or before and after the dressing, a nitrogen gas at a predetermined pressure and temperature and pure water or a chemical solution are atomized by the atomizer 16.
And sprays pure water or a liquid mixture of a chemical solution and nitrogen gas toward the polishing pad 10 from a spray nozzle 16 a of the atomizer 16. As a result, the mixed liquid is sprayed onto the polishing pad 10 in an atomized state, and the abrasive liquid and polishing debris on the polishing pad 10 are scattered outside the polishing table 11. In particular, the abrasive liquid and the polishing debris that have fallen into the concave portions of the polishing cloth can be scraped out by the gas in the mixed liquid, and further washed away with pure water or a chemical solution. This makes it possible to effectively remove the abrasive liquid and polishing debris present on the polishing cloth 10 that causes scratches. Such atomization can be performed at any time during the dressing by the second dresser 33, or at the second time.
It can be performed at any time before and after dressing by the dresser 33. As shown by the dotted lines in FIGS. 5 to 7, the atomization may be performed also at the time of initial surface adjustment of the polishing pad before polishing.

The water supplied to the polishing pad 10 from the polishing liquid / water supply nozzle and the mixed liquid jetted from the atomizer 16 to the polishing pad 10 are subjected to centrifugal force caused by the rotation of the polishing table 11, and are supplied to the outside of the polishing table 11. And is collected by the gutter 17a below the frame 17. After the dressing is completed, the second dresser 33 is returned to the standby position by swinging the dresser head 31, and is washed by the dresser washing tank 18 installed at the standby position.

Next, the semiconductor wafer is polished. During the polishing process of the semiconductor wafer, the top ring 23 is used.
At the same time as the polishing of the semiconductor wafer W is performed,
Dressing of the dressing unit 13 by the first dresser 39 is also performed. FIG. 4 shows such a state. In this case, the rotation of the support shaft 20 moves the top ring head 21 to a polishing position on the polishing cloth 10. Then, while rotating the top ring 23 and the polishing table 11 independently of each other, the semiconductor wafer W held on the top ring 23 and the polishing table 11 are relatively moved, and the semiconductor wafer W held on the lower surface of the top ring 23 is rotated. Is pressed against the polishing cloth 10 on the polishing table 11.
At this time, the polishing cloth 1
The abrasive liquid is supplied to the upper surface of the zero. As this abrasive liquid, for example, a suspension of abrasive grains composed of fine particles in an alkaline solution is used, and the semiconductor wafer W is polished by a combined action of chemical polishing by alkali and mechanical polishing by abrasive grains. You. The polishing liquid used for polishing is the polishing table 1
Receiving the centrifugal force caused by the rotation of 1, it is scattered outside the polishing table 11 and collected by the gutter 17 a at the lower part of the frame 17.

During such polishing, a swing motor 36 fixed to the support portion 35 of the dressing unit 13 is driven to swing the swing arm 37 and housed in the dresser cleaning tank 47 of the support base 46. The first dresser 39 is moved onto the polishing pad 10. And the first dresser 39
Is rotated by the rotation motor 43, and the diamond dresser 48 held by the first dresser is brought into contact with the polishing cloth 10 at a predetermined pressure to dress the polishing cloth 10.

During the dressing, the swing motor 36
Swings the swing arm 37 and the first dresser 39. The control device 50 controls the swing speed of the first dresser 39 to change depending on the position on the polishing table 11.
The motor speed of the swing motor 36 is controlled. The swing speed of the first dresser 39 is controlled based on the profile of the polished surface of the semiconductor wafer W. That is, it is controlled to move slowly at the position of the polishing cloth 10 for polishing a portion where the film thickness to be polished is thick, and to move quickly at the position of the polishing cloth 10 for polishing a portion where the film thickness to be polished is thin. Therefore,
Since the polishing cloth used for polishing a portion having a large thickness to be polished is dressed and sharpened more than a polishing cloth used for polishing a portion having a small thickness to be polished, the top ring 23 In addition, a portion having a large thickness to be polished can be polished relatively large, and a portion having a small film thickness can be polished relatively small, so that excessive or insufficient polishing can be eliminated.
The dressing time of the first dresser 39 during polishing of the semiconductor wafer W can be arbitrarily selected. Further, the control device 50 of the present embodiment controls the swing speed of the first dresser 39, but controls the rotation motor (rotation mechanism) 43 or the air cylinder (pressing mechanism) 40 to control the first dresser 39. By controlling the rotation speed or the pressing load of, it is also possible to eliminate excess or deficiency of polishing.

In the example shown in FIG. 6, the initial surface adjustment of the polishing cloth before polishing is performed not by the second dresser 33 but by the first dresser 39, and the other points are the same as those of the example shown in FIG. It is. In this manner, the first dresser 39 can perform coarsening for initial surface adjustment. Also, as in the example shown in FIG.
The dresser 33 can be used only when the polishing pad 10 is replaced, and the subsequent dressing can be performed by the first dresser 39. Since the polishing pad 10 before use is not sharpened at all, the dressing time for the initial surface adjustment becomes longer. On the other hand, the polishing cloth 10 once dressed is
After that, the polishing efficiency is increased only by light dressing. Therefore, in the example shown in FIG. 7, the initial surface adjustment is performed in a short time by the large-diameter second dresser 33 and the small-diameter first dresser 39 is used to sharpen a portion requiring dressing. Such a method is a suitable dressing method when dressing cannot be performed during polishing due to a combination of a polishing object and a polishing slurry to be used, due to a polishing process.

As described above, the polishing apparatus according to the present invention uses the first dresser 39 having a smaller diameter than the semiconductor wafer W to be polished, so that the region to be dressed in the region of the polished surface can be arbitrarily set. Therefore, it is possible to adjust the amount of sharpening at an arbitrary position on the polished surface. Therefore, appropriate polishing according to the profile (film thickness distribution) of the surface to be polished of the semiconductor wafer W can be performed.

Here, for example, the distribution of the film thickness to be polished of the semiconductor wafer W, that is, the profile of the surface to be polished of the semiconductor wafer W is assumed in advance according to the film forming method and the film forming apparatus, and based on this profile. At least one of the swing speed, rotation speed, and pressing load of the first dresser 39 may be controlled by a program. Further, as shown in FIGS. 2 to 4, the semiconductor wafer W before or during polishing is
Thickness measuring device 100 for measuring the profile of the surface to be polished
And the swing speed, rotation speed, and rotation speed of the first dresser 39 for each semiconductor wafer based on the actual profile of the surface to be polished of the semiconductor wafer W measured by the film thickness measuring device.
At least one of the pressing loads may be controlled. When the film thickness measuring device 100 is provided as described above,
More appropriate polishing can be performed for each semiconductor wafer. Further, as described above, the semiconductor wafer W
When measuring the profile of the surface to be polished,
Furthermore, a pad profiler for measuring the profile of the polished surface of the polishing cloth 10 is provided to measure the profile of the polished surface, and the first profile is determined based on the profiles of both the polished surface of the semiconductor wafer W and the polished surface of the polishing cloth 10. Dresser 3
9 at least one of the rocking speed, rotation speed and pressing load
One may be controlled.

The dressing of the polishing pad 10 can be performed according to the flow shown in FIG. That is, after the initial surface adjustment by the second dresser 33,
The dressing is performed by the first dresser 39, and the semiconductor wafer W is polished. After polishing the semiconductor wafer W,
It is determined whether the polishing performance of the polishing cloth 10 is properly maintained. If the polishing performance is not properly maintained, the polishing cloth 10 is dressed over the entire surface by the second dresser 33 having a large diameter. In order to determine whether the polishing performance is appropriately maintained, the profile of the polished surface of the polished semiconductor wafer W is measured by the film thickness measuring device 100, and the measured profile satisfies a predetermined level. It is determined whether or not. In this way, when the polishing surface is locally worn, the polishing cloth 10 is locally worn by dressing by the first dresser 39 by sharpening the substantially entire surface of the polishing surface with the second dresser 33 having a large diameter. In this case, the state of the polishing pad 10 can be reset by the second dresser 33.

Next, a polishing apparatus according to a second embodiment of the present invention will be described in detail with reference to FIGS. Note that the same reference numerals are given to members or elements having the same operations or functions as the members or elements in the above-described first embodiment, and portions that are not particularly described are denoted by the first symbols.
This is the same as the embodiment. FIG. 9 is a longitudinal sectional view schematically showing a main part of a polishing section in the present embodiment, and FIGS. 10 and 11.
FIG. 3 is a plan view schematically showing a polishing unit according to the embodiment.

As shown in FIGS. 9 to 11, the polishing apparatus according to the present embodiment includes a first dressing unit 52 having a first dresser 73 for dressing a polishing cloth during polishing, and a polishing cloth before polishing. A second dressing unit 51 having a second dresser 63 for roughening for initial surface adjustment is separately provided.

The first dressing unit 52 includes a ball screw 70 extending in the horizontal direction, a dresser shaft 72 hanging from a nut 71 on the ball screw 70, and a substantially disk-shaped first dresser 73 connected to the lower end of the dresser shaft 72. And A ball screw drive motor 74 is connected to one end of the ball screw 70. The ball screw 70 is rotated by the driving of the ball screw drive motor 74, and the nut 71 on the ball screw 70 and the first dresser 73 connected to the nut 71 can move in the horizontal direction by the action of the ball screw 70. Thereby, the first dresser 73 moves the dressing position on the polishing pad 10 and the polishing table 1 as shown by an arrow E in FIG.
A reciprocating movement is possible between the outside and the standby position. The ball screw drive motor 74 is connected to a control device 80, and the control device 80 controls the motor speed (swing speed). This ball screw drive motor 74
Constitutes a moving mechanism for moving the first dresser 73 on the polishing table 11.

Further, the first dresser 73 is connected to a rotary motor (rotating mechanism) 75 and an air cylinder (pressing mechanism) 76 fixed on a nut 71 of a ball screw 70 via a dresser shaft 72, whereby the first dresser 73 is connected. It can move up and down and rotate around the dresser shaft 72. Note that a dresser cleaning tank 77 for cleaning the first dresser 33 is arranged at a standby position outside the polishing table 11.

Here, similarly to the first embodiment, the first dresser 73 has a disk-type diamond dresser 78 as a dressing member, and the diameter of the first dresser 73 is the semiconductor wafer W to be polished.
Is smaller than the diameter. Therefore, the area of the polished surface dressed by the first dresser 73 is smaller than the area of the polished surface used for polishing the semiconductor wafer W.

The second dressing unit 51 includes a rotatable support shaft 60, a dresser head 61 connected to the upper end of the support shaft 60, a dresser shaft 62 hanging from a free end of the dresser head 61, and a dresser shaft 62. A substantially disk-shaped second dresser 63 connected to the lower end
And The second dresser 63 moves in the horizontal direction with the swinging of the dresser head 61 due to the rotation of the support shaft 60, and the dressing position on the polishing pad 10 and the standby position outside the polishing table 11 as shown by the arrow D in FIG. A reciprocating motion is possible between and. Further, the second dresser 63 is connected via a dresser shaft 62 to a motor (not shown) provided inside the dresser head 61 and an elevating cylinder, whereby the second dresser 63 can be moved up and down and can rotate around the dresser shaft 62. I have.

Here, the second dresser 63 has a pellet type diamond dresser 64 as a dressing member, as in the first embodiment. The diameter of the second dresser 63 is the same as the semiconductor wafer W to be polished. Is larger than the diameter. Therefore, the area of the polished surface dressed by the second dresser 63 is larger than the area of the polished surface used for polishing the semiconductor wafer W.

Next, a description will be given of an operation in a case where a polishing process and a dressing of a semiconductor wafer are performed by using the polishing apparatus having the above configuration. Hereinafter, only the operation corresponding to the example shown in FIG. 5 of the first embodiment will be described, but it goes without saying that the operation corresponding to the example shown in FIGS. 6 to 8 is also possible.

First, the case where the initial surface adjustment of the polishing cloth before polishing is performed will be described. In the initial surface adjustment of the polishing cloth before polishing, roughening is performed by thinly shaving the surface of the polishing cloth 10 using the second dresser 63 of the second dressing unit 51. FIG. 10 shows such a state. In this case, the dresser head 61 is moved to a dressing position on the polishing pad 10 by rotating the support shaft 60. Then, while independently rotating the second dresser 63 and the polishing table 11, the diamond dresser 64 held by the second dresser 63 is brought into contact with the polishing cloth 10 at a predetermined pressure. Thus, the second
The dresser 63 regenerates the entire polishing surface of the polishing cloth 10. After the dressing, the second dresser 63 is returned to the standby position by swinging the dresser head 61, and is washed by the dresser cleaning tank 18 installed at the standby position.

Next, the semiconductor wafer is polished. During the polishing process of the semiconductor wafer, the top ring 23 is used.
At the same time as the polishing of the semiconductor wafer W is performed,
Dressing of the first dressing unit 52 by the first dresser 73 is also performed. FIG. 11 shows such a state. In this case, the rotation of the support shaft 20 moves the top ring head 21 to a polishing position on the polishing cloth 10. Then, the top ring 23 and the polishing table 1
The semiconductor wafer W held on the top ring 23 and the polishing table 11 are moved relative to each other while rotating the semiconductor wafers 1 independently of each other. Press 10 At this time, the abrasive liquid is simultaneously supplied from the abrasive liquid / water supply nozzle 15 to the upper surface of the polishing cloth 10, and the semiconductor wafer W is polished.

During such polishing, the ball screw drive motor 74 of the first dressing unit 52 is driven to drive the first dresser 73 stored in the dresser cleaning tank 77.
Is moved onto the polishing pad 10. Then, the first dresser 73 is rotated by the rotation motor 75, and the diamond dresser 78 held by the first dresser 73 is brought into contact with the polishing cloth 10 at a predetermined pressure to dress the polishing cloth 10.

During this dressing, the first dresser 73 is moved by the ball screw driving motor 74 to the polishing table 1.
1 is swung in the radial direction of the table 11. The control device 80 controls the motor speed of the ball screw drive motor 74 so that the swing speed of the first dresser 73 changes depending on the position on the polishing table 11. The swing speed of the first dresser 73 is controlled based on the profile of the polished surface of the semiconductor wafer W. That is, at the position of the polishing cloth 10 for polishing a portion where the film thickness to be polished is thick,
At the position of the polishing pad 10 for polishing a portion having a small film thickness to be polished, the polishing pad 10 is controlled to move quickly. Therefore, the polishing cloth used for polishing a portion having a large thickness to be polished is dressed and sharpened more than the polishing cloth used for polishing a portion having a small thickness to be polished. In No. 23, a portion having a large thickness to be polished can be polished relatively large and a portion having a small thickness can be polished relatively small, so that excessive or insufficient polishing can be eliminated. In addition,
The dressing time of the first dresser 73 during polishing of the semiconductor wafer W can be arbitrarily selected. In addition, the control device 50 of the present embodiment controls the swing speed of the first dresser 73, but controls the rotation motor (rotation mechanism) 75 and the air cylinder (pressing mechanism) 76 to control the first dresser 73. By controlling the rotation speed or pressing load of the
Similarly, it is possible to eliminate excessive or insufficient polishing.

As described above, in the polishing apparatus according to the present invention, by using the first dresser 73 having a smaller diameter than the semiconductor wafer W to be polished, the region to be dressed in the region of the polished surface can be arbitrarily set. Since it can be changed, it is possible to adjust the amount of sharpening at an arbitrary position on the polishing surface. Therefore, appropriate polishing according to the profile (film thickness distribution) of the surface to be polished of the semiconductor wafer W can be performed.

As in the first embodiment, a profile of the surface to be polished of the semiconductor wafer W is assumed in advance according to, for example, a film forming method and a film forming apparatus, and the swing of the first dresser 73 is performed by a program based on this profile. At least one of the dynamic speed, the rotation speed, and the pressing load may be controlled, or a film thickness measuring device for measuring the profile of the surface to be polished of the semiconductor wafer W before polishing is provided. It is also possible to control at least one of the swing speed, the rotation speed, and the pressing load of the first dresser 73 for each semiconductor wafer based on the profile of the actual polished surface of the semiconductor wafer W measured by the measuring device. Good.

In the first and second embodiments, a diamond dresser is used as a dressing member of the second dresser and the first dresser, but the present invention is not limited to this. For example, not only a pellet-type or disk-type diamond dresser but also a ring-type diamond dresser or a brush dresser can be used. These various dressing members can be used in appropriate combinations.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment, and may be implemented in various forms within the scope of the technical idea. Needless to say.

[0065]

As described above, according to the present invention, by using a dresser having a smaller diameter than the object to be polished,
The area to be dressed in the area of the polishing surface can be arbitrarily changed. Therefore, it is possible to dress and dress the polishing cloth used for polishing a portion having a large thickness to be polished more than the polishing cloth used for polishing a portion having a small thickness to be polished. . Thereby, a relatively thick portion having a large film thickness to be polished and a relatively small portion having a thin film thickness can be polished. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a plan view schematically showing a polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a longitudinal sectional view schematically showing a main part of a polishing section of the polishing apparatus according to the first embodiment of the present invention.

FIG. 3 is a plan view schematically showing a polishing section of FIG. 1, showing a state when an initial surface of the polishing pad is adjusted.

FIG. 4 is a plan view schematically showing the polishing section of FIG. 1, showing a state during polishing by a top ring;

FIG. 5 is a timing chart showing a series of operation examples of the polishing section of FIG. 2;

FIG. 6 is a timing chart showing a series of operation examples of the polishing section of FIG. 2;

FIG. 7 is a timing chart showing a series of operation examples of the polishing section of FIG. 2;

FIG. 8 is a flowchart showing an example of a series of operations of the polishing unit of FIG. 2;

FIG. 9 is a longitudinal sectional view schematically showing a main part of a polishing section of a polishing apparatus according to a second embodiment of the present invention.

FIG. 10 is a plan view schematically showing a polishing unit of a polishing apparatus according to a second embodiment of the present invention, showing a state when an initial surface of a polishing cloth is adjusted.

FIG. 11 is a plan view schematically showing a polishing section of a polishing apparatus according to a second embodiment of the present invention, showing a state during polishing by a top ring.

FIG. 12 is a cross-sectional view schematically showing a conventional polishing apparatus.

[Explanation of symbols]

 1a, 1b Polishing unit 2a, 2b Semiconductor wafer storage cassette 4a, 4b Transfer robot 5, 6 Reversing machine 7a, 7b, 8a, 8b Washing machine 10 Polishing cloth 11 Polishing table 11a Table shaft 12 Top ring unit 13 Dressing unit 14 Pusher 15 Abrasive liquid / water supply nozzle 16 Atomizer 16a Injection nozzle 17 Frame 17a Gutter 18, 47, 77 Dresser washing tank 20, 30, 60 Support shaft 21 Top ring head 22 Top ring shaft 23 Top ring 31, 61 Dresser head 32, 38, 62, 72 Dresser shaft 33, 63 Second dresser 34, 48, 64, 78 Dressing member 35 Supporting part 36 Swing motor 36a Motor shaft 37 Swing arm 39, 73 First dresser 40 Air syringe 41 rotating cylinder 42,45 timing pulley 43 rotating motor 44 timing belt 46 support base 50,80 controller 51 second dressing unit 52 first dressing unit 70 ball screw 71 nut 74 ball screw drive motor 75 rotation motor 76 air cylinder 100 film thickness measurement vessel

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 21/304 622 H01L 21/304 622K 622R 622S (72) Inventor Makoto Akagi 11 Asahimachi Haneda, Ota-ku, Tokyo No. 1 Inside EBARA CORPORATION (72) Katsuhiko Tokushige, Inventor 11-1 Haneda Asahimachi, Ota-ku, Tokyo Inside Ebara Corporation (72) Inventor Naosuke Matsuo 11-1, Haneda Asahi-cho, Ota-ku, Tokyo Stock Company EBARA CORPORATION (72) Inventor Manabu Tsujimura 11-1 Haneda Asahimachi, Ota-ku, Tokyo F-term in EBARA CORPORATION (reference) 3C047 AA04 AA05 AA34 FF08 FF09 FF19 3C058 AA12 AA16 AA19 AB04 AC02 AC05 BA04 BA07 CB01 CB01 DA17

Claims (10)

[Claims] A polishing table having a polishing surface; and a top ring pressing a polishing object on the polishing surface of the polishing table, wherein the polishing object is pressed against the polishing surface of the polishing table. In a polishing apparatus for polishing, a dresser for sharpening the polishing surface of the polishing table, the dresser, a region of the polishing surface used to polish a predetermined position in the surface to be polished of the object to be polished, A polishing apparatus characterized in that sharpening is performed according to a film thickness to be polished at a predetermined position in the surface to be polished. 2. A polishing table having a polishing surface, and a top ring for pressing a polishing object on the polishing surface of the polishing table, wherein the polishing object is pressed against the polishing surface of the polishing table. A dressing device for sharpening the polishing surface of the polishing table; a moving mechanism for moving the dresser on the polishing surface of the polishing table; a rotating mechanism for rotating the dresser;
At least one of a pressing mechanism for pressing the dresser against the polishing surface of the polishing table; and a polishing surface region used for polishing a predetermined position of the polishing object on the polishing surface, wherein Controlling at least one of a moving speed of the dresser by the moving mechanism, a rotating speed of the dresser by the rotating mechanism, and a pressing load of the dresser by the pressing mechanism in accordance with a film thickness to be polished at a predetermined position. A polishing apparatus, comprising: a control device. 3. The dresser according to claim 1, wherein the dresser is a dresser having a smaller diameter than the object to be polished.
Or the polishing apparatus according to 2. 4. The polishing apparatus according to claim 1, wherein the dresser sharpens the polished surface during polishing. 5. The polishing apparatus according to claim 1, further comprising a cleaning tank for cleaning the dresser. 6. The polishing apparatus according to claim 1, further comprising a film thickness measuring device for measuring a film thickness to be polished on the surface to be polished of the object to be polished. apparatus. 7. The polishing apparatus according to claim 1, further comprising a second dresser for sharpening substantially the entire polishing surface against which the object to be polished is pressed. apparatus. 8. The polishing apparatus according to claim 7, wherein the second dresser sharpens substantially the entire polishing surface when the polishing surface is locally worn. 9. The polishing apparatus according to claim 7, wherein the second dresser is a dresser having a diameter larger than that of the object to be polished. 10. A polishing table having a polishing surface, and a top ring for pressing a polishing object on the polishing surface of the polishing table, wherein the polishing object is pressed against the polishing surface of the polishing table. A first dresser for sharpening a polished surface of the polishing table during polishing of the object to be polished; and a sharpening of a polished surface of the polishing table when the object to be polished is not polished. A polishing apparatus comprising a dressing unit integrated with a second dresser for performing polishing.