JP2000061838A - Dressing device and dressing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To dress an abrasive cloth always in a stable constant condition, and to flatly dress the outer surface of the abrasive cloth by a minimum degree of dressing. SOLUTION: A dressing device is composed of a surface plate 1 for rotating an abrasive cloth 2 fixed on the outer surface thereof, in a horizontal plane, a dressing tool 13 for grinding the outer surface of the abrasive cloth 2 in order to dress the latter, a dressing head 11 mounted to a column 12 so as to be vertically movable, for holding the dressing tool 13 which is therefore opposed to the abrasive cloth 2 on the surface plate 1, an electric motor 15 coupled to the dressing head 11, for rotating the dressing tool 13, a precise feed mechanism 32 for vertically feeding the dressing head 11 so as to press the dressing tool 13 against the abrasive cloth 2, a second electric motor 34 for driving the precise feed mechanism 32, and a positional control means for controlling the position of the dressing tool 13 so as to feed the latter by a preset degree.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dressing apparatus and method applied to a chemical mechanical polishing apparatus for polishing a wafer in a semiconductor manufacturing process, and more particularly, to the life of a polishing cloth of the chemical mechanical polishing apparatus. TECHNICAL FIELD The present invention relates to a dressing device and a method capable of extending and stable dressing.

[0002]

2. Description of the Related Art In chemical mechanical polishing processing (CMP processing) of a wafer, high precision flatness is required. Therefore, the polishing cloth used in the chemical mechanical polishing apparatus (CMP apparatus) is It is essential to dress appropriately. If CMP processing is continued with a polishing cloth that has undulations on the surface or is clogged during processing, the wafer cannot be polished flatly with high precision, and the polishing amount per unit time decreases, This is because a serious inconvenience occurs such that the polishing amount cannot be controlled.

Some CMP apparatuses of this type have a device for dressing a polishing cloth. A dressing tool such as a diamond dresser on which diamond is electrodeposited is used for dressing the polishing cloth with the CMP apparatus. This dressing tool grinds the surface of the polishing cloth having undulations or clogging to shape the polishing surface of the polishing cloth flat.

Therefore, FIG. 10 shows a side view of a conventional pressure control type dressing apparatus. In FIG. 10, reference numeral 1 indicates a surface plate of the CMP apparatus. The polishing cloth 2 is fixed to the upper surface of the surface plate 1 by pasting it. The surface plate 1 is supported by a rotary shaft 3 so as to rotate on a horizontal plane, and the rotary shaft 3 is driven by a motor (not shown).

Reference numeral 4 is a polishing head. A backing pad 5 is attached to the lower surface of the polishing head 4, and the wafer 6 is sucked and held by the polishing head 4 via the backing pad 5. Reference numeral 7 denotes a guide ring provided outside the backing pad 5 in order to prevent the wafer 6 from popping out during polishing.

Reference numeral 8 denotes a rotary shaft of the polishing head 4, and the rotary shaft 8 receives a rotational force from, for example, a motor provided on a turning arm (not shown). The polishing head 4 is also connected via a rotary shaft 8 to an air cylinder (not shown) provided on the turning arm side. Therefore, the polishing head 4 is capable of moving in a horizontal plane and moving up and down in the vertical direction as the swiveling arm swivels. When polishing, the wafer 6 held by the polishing head 4 is moved to a predetermined position by an air cylinder. It can be pressed against the polishing cloth on the surface plate 1 by the surface pressure. In addition, 9 has shown the slurry supply nozzle which supplies the slurry required for CMP processing to the surface plate 1.

A dressing device 10 is attached to the CMP device. Reference numeral 11 is a dressing head, and 12 is a column that supports the dressing head. As a dressing tool, a ring-shaped dresser 13 made of an electroplated diamond grindstone is fixed to the lower surface of the dressing head 11. The dressing head 11 has a rotating shaft 1.
4 is connected to one end of the rotary shaft 14, and the other end of the rotary shaft 14 is
A motor 1 for rotating the dressing head 11.
It is connected with 5. The air cylinder 16 for pressing the dresser 13 against the polishing cloth 2 with a predetermined surface pressure includes a bracket portion 1 extending horizontally from the motor 15 and the column 12.
It is provided so as to be connected with 7. The air cylinder 16 is a double rod type cylinder.

A housing 1 containing a motor 15
The reference numeral 8 is adapted to engage with a guide 19 mounted vertically on the side surface of the column 12 via a slider 20 so as to be slidable in the vertical direction.

In the CMP apparatus attached with the dressing apparatus 10, when a new polishing cloth 2 is used, the polishing cloth 2 is dressed before starting the CMP processing.
It is necessary to flatten the undulations on the surface of the polishing cloth 2.
Further, since the wafer is required to have a high degree of flatness, it is essential to appropriately dress the polishing cloth.
This is because if the polishing cloth becomes clogged, the amount of polishing per unit time will decrease, and the amount of polishing cannot be controlled, so it is necessary to eliminate the clogging.

In the conventional dressing apparatus 10, the dresser 13 is pressed by the air cylinder 16 and the polishing cloth 2 is dressed while applying a constant surface pressure. In order to make this pressing force constant, the pressure of the air supplied to the air cylinder 16 is set by a pressure control valve.

[0011]

Here, FIG. 11 shows a cross section in the circumferential direction of the polishing cloth 2 when dressing while keeping the surface pressure for pressing the dresser 13 constant. Figure 11
As shown in (a), the surface of the new polishing cloth 2 often has undulations in the circumferential direction. In order to remove the undulations from the surface of the polishing cloth 2, the dresser 13 is attached with an air cylinder.
When trying to dress with a certain pressure with 6,
The dresser 13 dresses the surface of the polishing cloth 2 while slightly moving up and down so as to follow the unevenness of the undulations. When a certain force is applied to the dresser 13 during this vertical movement, of the undulations on the surface of the polishing cloth 2,
Since both the convex portion and the concave portion are scraped off, the amount of scraping for flattening becomes large. In FIG. 11A, when the undulation is removed with the minimum dressing amount and the polishing cloth 2 can be made flat, the thickness of the polishing cloth 2 is t,
As shown in FIG. 11B, the thickness of the polishing pad 2 is actually smaller than t due to excessive dressing.
It becomes 1. For this reason, as a result, it takes a long time for the dressing to become flat, and in addition, the polishing cloth 2 originally obtained by the excessive dressing is used.
There was a problem that the actual life would be shorter than the life of. In addition, depending on the initial state of the polishing pad 2, there are variations in the degree of undulations and the like, and the time until the dressing is completed is not constant. This makes it difficult to control a stable dressing amount.

FIG. 12 shows a cross section in the radial direction of the polishing pad 2 when dressing while keeping the surface pressure for pressing the dresser 13 constant.

As shown in FIG. 12A, the polishing cloth 2
For the dressing situation in the radial direction of
The dressing amount tends to increase toward the outer peripheral portion and the inner peripheral portion, and as a result of the dressing, the radial cross-sectional shape of the obtained polishing cloth becomes a middle-height shape in which the central portion in the radial direction is thick. This is because the dresser 13 contacts the polishing cloth 2 for a long time on the inner peripheral side and the outer peripheral side of the polishing cloth 2.

By the way, when dressing is continuously performed with the same dresser 13, the dresser 13 itself is clogged, and the dressing ability of the dresser 13 gradually decreases. For stable CMP processing of the wafer, it is required that the polishing cloth is dressed with a constant quality even in the dressing step of the polishing cloth. However, in the past, the polishing cloth was dressed to a certain condition by managing the dressing time exclusively, so in reality, the dressing cloth could not be dressed to a certain condition as the dresser's ability deteriorated. There is a problem that comes.

Further, in the time management, the life of the dresser is determined empirically uniformly in advance, but specifically, the dressing progress varies considerably depending on the dresser. Is. Conventionally, the life of dressers could not be judged individually, and the dressers were uniformly dressed. Therefore, dressers with reduced dressing ability sometimes continued to dress the polishing cloth. Further, it is impossible to determine whether the polishing cloth is dressed with a dresser that has reached the end of its life, and it is the current situation that it cannot be known until an abnormality such as a decrease in the processing rate in the process of the CMP processing of the wafer.

Therefore, an object of the present invention is to solve the above-mentioned problems of the prior art and to be able to dress a polishing cloth in a stable and constant condition at all times.
It is an object of the present invention to provide a dressing apparatus and a dressing method that make it possible to dress the surface of a polishing cloth evenly with a minimum dressing amount.

Another object of the present invention is to provide a dressing device which can always stably perform dressing under the same condition even when the state of the dresser changes, and can accurately determine the life of the dresser. And to provide a dressing method.

[0018]

In order to achieve the above object, the present invention provides a dressing device for dressing a polishing cloth used in a chemical mechanical polishing apparatus, wherein the polishing cloth is fixed on the surface and is on a horizontal plane. With a surface plate that rotates the polishing cloth, a dressing tool that scrapes the surface of the polishing cloth and dresses, and is attached to the column so that it can move in the vertical direction, and face the polishing cloth on the surface plate. And a dressing head for holding the dressing tool, a first electric motor that is connected to the dressing head and drives the dressing tool to rotate, and the dressing head is sent in the vertical direction to press the dressing tool against the polishing cloth. A precision feed mechanism, a second electric motor for driving the precision feed mechanism, and the drain To send only feed amount set a single tool advance and is characterized by comprising a position control means for controlling the position of the dressing tool.

The precision feed mechanism is attached to a ball screw connected to the drive shaft of the second electric motor and a housing of the first electric motor which is screwed onto the ball screw and rotationally drives the dressing head. It consists of a ball screw mechanism consisting of a nut.

The position control means can be composed of an open loop position control means for rotating the second electric motor by a rotation angle corresponding to the set feed amount. Furthermore, a waviness measuring means for measuring the size of the waviness of the polishing cloth in the circumferential direction,
And a means for determining the minimum dressing amount based on the measurement result by the waviness measuring means, and the feed amount corresponding to this minimum dressing amount is set as the set feed amount.

In the dressing device according to the present invention as described above, the first dressing device is provided so that a stable dressing amount can be obtained even if the performance is lowered due to the dressing tool being misaligned.
A means for detecting the current supplied to the electric motor and a time point at which the current value starts to decrease and then starts to decrease after the dressing is started is determined to be the end of the dressing. It is preferable to further provide means.

Further, according to the present invention, in a dressing method for dressing a polishing cloth used in a chemical mechanical polishing apparatus, a dressing tool which is movable in the vertical direction and attached to a dressing head driven by an electric motor is The parallelism of the dressing tool is adjusted so as to face the fixed surface plate in parallel, and while the surface plate is rotated, the dressing tool is preset by position control with respect to the rotating polishing cloth. The dressing cloth is fed by the specified feed amount, the dressing cloth is dressed, and after the dressing is started, the current value supplied to the electric motor for driving the dressing head is increased, and then the current value is started to decrease. The dressing is terminated when the set value of

In this dressing method, the time until the end of dressing is measured every time, this dressing time is compared with a preset reference dressing time, and when the dressing time exceeds the reference dressing time, the dressing tool The dressing tool is replaced when it is judged to have reached the end of its service life.

Regarding the setting of the reference dressing time, the dressing rate of a standard dressing tool serving as a reference is measured in advance, and the reference dressing time is set based on the dressing rate.
Even if the dressing amount changes, the life of the dressing tool can be easily determined.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a dressing device and method according to the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an embodiment of the present invention, and reference numeral 30 is a dressing device attached to a CMP device. The CMP apparatus is shown in FIG.
The CMP apparatus is the same as that of the CMP apparatus of FIG.

In the dressing apparatus 30, 11 is a dressing head and 12 is a column for supporting the dressing head. As a dressing tool, a ring-shaped dresser 13 made of an electroplated diamond grindstone is fixed to the lower surface of the dressing head 11. The dressing head 11 is connected to one end of a rotary shaft 14, and the other end of the rotary shaft 14 is connected to a first electric motor 15 for rotationally driving the dressing head 11. The housing 18 in which the motor 15 is housed is slidably engaged with a guide 19 mounted vertically on the side surface of the column 12 via a slider 20.

As the precision feed mechanism 32 for feeding the dressing head 11 in the vertical direction, a ball screw mechanism driven by an electric motor 34 is used. That is,
A second electric motor 34, which is a pulse motor, is attached to the side surface of the column 12 via a bracket 35. The drive shaft 36 of the second electric motor is coaxial with the rotary shaft 14 of the dressing head 11 and is connected to a ball screw 38 via a coupling 37. The nut 40 that is screwed onto the ball screw 38 is
1 and is connected to the housing 18 of the first electric motor.

In FIG. 1, reference numeral 44 indicates a probe as a means for measuring the waviness of the surface of the polishing cloth 2.
The probe 44 can be moved horizontally by the air cylinder 45 as well as vertically. As a result, the tip of the probe 44 comes into contact with the surface of the polishing cloth 2 at an arbitrary position, and the waviness at that position can be measured.

Next, FIG. 3 shows a control device for controlling the precision feed mechanism 32. The control device 50 includes a calculation device 52.
A motor drive circuit 54 that drives the first electric motor 15 and the second electric motor 34, and a current value I of the first electric motor 15 that is fetched through the current detection unit 56 during dressing, A comparison unit 58 for comparing the current value I0 when the first electric motor 15 rotates with no load, and a timer 60 for measuring the time from the start to the end of dressing are provided.

Dressing of the polishing cloth will be described below with reference to FIGS. 1 to 4. As shown in FIG. 4A, the surface of the polishing cloth 2 having a waviness in the circumferential direction is dressed to remove the waviness and flatten it. In the dressing according to the present invention, the minimum dressing amount δ required to remove the undulations from the surface of the polishing pad 2 is preset. The dressing amount δ is equal to the polishing cloth 2
The thickness is to scrape off the surface of the
The precision feed mechanism 32 controls the position of the dresser 13 and corresponds to the set feed amount for feeding the dresser 13.
Regarding the dressing amount δ, data set to an appropriate value can be input to the arithmetic unit 52 via the input device 62, or the dressing amount δ can be set in the circumferential direction of the polishing cloth 2. It can also be set based on the actual measurement result of. Especially, the details of the setting at the time of start-up dressing performed on a new polishing cloth will be described later.

Further, in FIG. 2, before starting the dressing, the plane 8 including the dressing surface of the dresser 13 is used.
The relative positional relationship between the dressing head 11 and the surface plate 1 is adjusted so that 0 and the plane 82 including the upper surface of the surface plate 1 have an accurate parallelism. After that, in FIG. 3, the first electric motor 15 is driven to rotate the dressing head 11 at a predetermined rotation speed. At the same time, the second electric motor 34 is driven.

The arithmetic unit 52 calculates a command pulse corresponding to the input dressing amount δ. The command pulse generated by the arithmetic unit 52 has a rotation angle of the second electric motor 34 corresponding to the dressing amount δ and a predetermined rotation speed at the same time, and the motor drive circuit 54 is commanded by the command pulse. The second electric motor 34 is driven at the rotation angle and the rotation speed.

The second electric motor 34 has a ball screw 3
Rotate 8. Since the nut 40 changes the rotation of the ball screw 38 into a linear motion, the dresser 13 attached to the dressing head 11 advances by a distance corresponding to the dressing amount δ while the position is controlled by the open loop method.

As shown in FIG. 4 (b), during such position control, the dresser 13 is pressed against the polishing cloth 2 while rotating, and the surface of the polishing cloth 2 is scraped off and gradually advanced. To do. Then, the second electric motor 34 is stopped when the dresser 13 advances by a distance corresponding to the dressing amount δ from the start of dressing, and stops until the flattening ends. After that, the second electric motor 34 rotates in the reverse direction, and the dressing head 11 rises. As a result, from the surface plate 1 to the dresser 1
3 is separated, and dressing for the polishing cloth 2 is completed.

In this way, the flat surface 80 including the dressing surface of the dresser 13 and the flat surface 82 including the upper surface of the surface plate 1 are formed.
By precisely aligning and, and sending the dresser 13 while precisely controlling the position of the dresser 13, the dressing amount δ, which is the minimum required to flatten the surface of the polishing pad 2, is accurately controlled. be able to. Therefore, as shown in FIG. 11B, when dressing is performed while pressing the dresser 13 with a constant pressing force as in the conventional case, the dressing becomes excessive due to a slight vertical movement of the dresser 13. However, according to the present method, dressing is performed. There will be no inconvenience that the thickness t1 of the polishing pad 2 later becomes thinner than the expected thickness. As shown in FIG. 4C, as for the thickness of the polishing pad 2 after the dressing is finished, the thickness t (t> t1) as originally planned with a minimum dressing for flattening was added. It can be reliably obtained, and the polishing cloth 2 is not wasted.

FIG. 5 shows the polishing cloth 2 after dressing.
FIG. 12 shows the shape in the radial direction, but by performing dressing while precisely controlling the position of the dresser 13, it is possible to prevent the surface from having a medium height as in the constant pressure method of FIG. Since the dressing can be performed in a flat shape in the radial direction as well, the surface of the polishing pad 2 can be uniformly flattened as a whole.

Next, in the dressing-finished polishing cloth 2, in FIG. 1, the dressing head 11 moves up to the standby position, but the polishing head 4 moves down. Then, the wafer 6 is pressed against the polishing cloth 2 whose polishing ability has been restored by dressing, and the CMP process for the interlayer insulating film or the metal film on the surface of the wafer 6 is restarted while rotating the surface plate 1. If the polishing cloth 2 is clogged while the CMP processing is continued, dressing is performed by the dressing amount δ as appropriate. Since this dressing amount is minimum as described above, the polishing cloth 2 can be used for a long time while being dressed many times without wasting it.

By the way, when the polishing cloth 2 is replaced with a new one and the start-up dressing is performed, it is necessary to obtain the minimum required minimum dressing amount δ according to the initial state of the new polishing cloth 2. Therefore, the setting of the minimum dressing amount δ during this start-up dressing will be described.

In the new polishing cloth 2, the state of the undulations of undulations generated on the surface of the new polishing cloth 2 is different for each polishing cloth. Therefore, according to the uniformly set dressing amount, one dressing cloth has excessive dressing and the other dressing cloth has incomplete dressing. Therefore, the waviness at a plurality of locations is measured by the probe 44 provided as the waviness measuring means, and the minimum dressing amount δ is determined based on the measurement result.

FIG. 6 is a diagram showing an example of measuring points of the waviness of the polishing cloth 2 in the circumferential direction. In this embodiment,
The undulation in the circumferential direction of the surface of the polishing pad 2 is measured as follows with the three points A, B and C as measurement points. In FIG. 2, when the distance from the center of rotation of the polishing pad 2 to the center of the probe 44 is r, first, in the measurement at point A, the probe 44 is positioned at the position r1. Then, when the displacement of the probe 44 is measured while slowly rotating the surface plate 1, the undulation at the measurement point A is obtained as a displacement curve as shown in FIG. 7, as shown in FIG. 7. In the same way, the displacement curve of the undulation in the circumferential direction of the measurement points B and C can be obtained. To obtain such a displacement curve, the output of the probe 44 is introduced into the arithmetic unit 52. The arithmetic unit 52 determines the lowest point dmi from these displacement curves.
Finding n and the highest point dmax, the lowest point dmin and the highest point dmax
The distance between them is set as the minimum dressing amount δ required for flattening. By setting the minimum dressing amount δ in this manner, it is possible to remove the undulations and flatten the polishing cloth 2 without wastefully dressing it.

The minimum dressing amount δ is set at the time of start-up dressing, and the waviness in the circumferential direction of the polishing pad 2 is appropriately measured as described above when dressing is performed during the CMP process. The minimum dressing amount δ at the time of start-up dressing may be updated based on the measurement result.

Further, as a means for measuring the waviness of the polishing cloth 2 in the circumferential direction, a non-contact type displacement sensor may be applied instead of the contact type displacement sensor comprising a probe as in the present embodiment. it can.

Next, another embodiment of the present invention will be described with reference to FIGS. In FIG.
In this embodiment, the current value I of the current supplied to the first electric motor 15 rotating the dressing head 11 is detected by the current detector 56, and the dressing is performed while the arithmetic unit 52 monitors the change in the current value I. .

As shown in FIG. 8, when dressing is started (time t1), the initial load acting on the dresser 13 causes the motor current flowing through the first electric motor 15 to rise. As the dresser 13 dresses the surface of the polishing cloth 2, the motor current gradually decreases. During this time, the dresser 13 dresses the polishing cloth 2 with a feed amount corresponding to the minimum dressing amount δ.

However, it is possible that the dresser 13 is worn, clogged, or the like, and the dressing ability is reduced. In such a dresser 13, the polishing cloth 2 is not always surely dressed by the minimum dressing amount δ when the dressing 13 is fed by the amount corresponding to the minimum dressing amount δ.

Therefore, in FIG. 3, the arithmetic unit 52 is
During dressing, the comparator unit 58 compares the detected value I of the motor current with the current value I0 in the case of no load to monitor the change in the motor current. Then, the motor current I is I0
When it coincides with (t2), it is determined that the dressing is finished, and the dressing is finished. That is, the dresser 13 is sent by the minimum dressing amount δ, and since the dressing 13 is not subjected to the processing load from the polishing cloth 2, the dressing is performed at this point regardless of the state of the dresser 13. It can be judged that the end. Therefore, a stable dressing amount can be obtained even if the dressing ability of the dresser 13 is deteriorated due to abrasion of abrasive grains or clogging.

Monitoring the motor current I in this way also has the following advantages. That is, when dressing is repeated under the same condition of the minimum dressing amount δ, the change curve of the motor current I changes.
For example, when the dresser 13 is heavily clogged, as shown by the dotted line in FIG. 8, the time (t3) until the motor current I matches the no-load motor current value I0 is prolonged. Conversely, if the reference dressing time T0 is set in advance for the same minimum dressing amount δ, the arithmetic unit 52 keeps the dressing time at the reference dressing time T0 while the timer 60 measures the time. It is possible to judge that the life of the dresser 13 is exceeded. The dresser 13 that has reached the end of its life may be replaced with a new dresser.

Next, the reference dressing time T0 is shown in FIG.
It is preferable to set as shown in. Prepare a standard dresser that will serve as the basis for calculating the dressing time. Then, the dressing cloth 2 is experimentally dressed with this standard dresser under the condition that the value of δ is variously changed by using the minimum dressing amount δ as a parameter, and as described in FIG. Get dressing time in. The dressing time and the dressing amount δ are in a proportional relationship, and as shown in FIG. 9, a dressing rate curve for a normal dresser is obtained.

Therefore, for example, assuming that the target minimum dressing amount is δ1, this dressing rate curve can be used to easily find the reference dressing time T1 corresponding to the target minimum dressing amount δ1. .

If the dressing rate curve by the standard dresser is prepared in advance as described above, the dressing time can be easily obtained even if the value of the minimum dressing amount δ is changed. Based on this dressing time, dresser 13
It is possible to determine the life of the.

[0051]

As is apparent from the above description, according to the present invention, the polishing cloth can be dressed in a stable and constant condition, and the surface of the polishing cloth can be dressed with a minimum dressing amount. It becomes possible to dress flatly.

Further, according to the present invention, even if the dresser's state changes and its performance decreases, or the dressing amount changes, it is possible to always perform stable dressing under the same condition, and to improve the life of the dresser. Can make accurate judgments

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a dressing device according to the present invention.

FIG. 2 is a side view when the dressing device in FIG. 1 is measuring waviness in a circumferential direction of a polishing cloth.

FIG. 3 is a block configuration diagram of a precision feed mechanism that feeds a dressing tool and a control device that controls the position of the dressing tool.

FIG. 4 is a diagram showing changes in the circumferential shape of the polishing cloth during dressing.

FIG. 5 is a diagram showing the shape of the polishing cloth in the radial direction at the end of dressing.

FIG. 6 is a view showing an example of measurement points of waviness of a polishing cloth in a circumferential direction.

FIG. 7 is a diagram showing a change curve of waviness at each measurement point.

FIG. 8 is a diagram showing a change in motor current during dressing.

FIG. 9 is a diagram showing a dressing rate curve obtained by using a standard dressing tool.

FIG. 10 is a side view of a conventional pressure control type dressing device.

11 is a view showing the shape of the polishing cloth dressed by the dressing device of FIG. 10 in the circumferential direction.

12 is a view showing the radial shape of the polishing pad dressed by the dressing device of FIG.

[Explanation of symbols]

1 surface plate 2 polishing cloth 4 Polishing head 6 wafers 11 Dressing head 12 columns 13 Dresser (dressing tool) 15 First electric motor 30 dressing equipment 32 Precision feed mechanism 34 Second electric motor 38 ball screw 40 nuts 44 probes

Continued front page    (72) Inventor Takashi Ito             2068 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd.             Company Numazu Office (72) Inventor Takahiro Kawamen             2068 Ooka, Numazu City, Shizuoka Prefecture Toshiba Machine Co., Ltd.             Company Numazu Office F term (reference) 3C047 AA05 AA08 AA15 AA34 AA38

Claims (8)

[Claims] 1. A dressing device for dressing a polishing cloth used in a chemical mechanical polishing apparatus, wherein the polishing cloth is fixed to a surface and the polishing cloth is rotated on a horizontal surface; and the surface of the polishing cloth is scraped. , Dressing tools for dressing, and vertically mounted on the column,
A dressing head that holds the dressing tool facing the polishing cloth on the surface plate, a first electric motor that is connected to the dressing head, and drives the dressing tool to rotate, and feeds the dressing head in a vertical direction. A precision feed mechanism for pressing the dressing tool against the polishing cloth; a second electric motor for driving the precision feed mechanism; and a position of the dressing tool for feeding the dressing tool by a preset feed amount. And a position control means for controlling the dressing device. 2. The precision feed mechanism is a ball screw connected to a drive shaft of the second electric motor, and a housing of a first electric motor which is screwed to the ball screw and rotationally drives the dressing head. The dressing device according to claim 1, wherein the dressing device has an attached nut. 3. The dressing device according to claim 1, wherein the position control means is an open loop position control means for rotating the second electric motor by a rotation angle corresponding to the set feed amount. . 4. The position control means has a waviness measuring means for measuring the size of the waviness of the polishing cloth in the circumferential direction, and a means for obtaining a minimum dressing amount based on the measurement result by the waviness measuring means. The dressing device according to any one of claims 1 to 3, wherein a feed amount corresponding to the minimum dressing amount is set as the set feed amount. 5. A means for detecting a current supplied to the first electric motor, and a current value which starts to decrease after starting the dressing and then starts to decrease to a predetermined set value. The dressing device according to claim 1, further comprising a unit that determines that the time point when the dressing is finished. 6. A dressing method for dressing a polishing cloth used in a chemical mechanical polishing apparatus, wherein a dressing tool movable in a vertical direction and attached to a dressing head driven by an electric motor fixes the polishing cloth. Adjust the parallelism of the dressing tool so as to face the plate in parallel, while rotating the surface plate, only the feed amount preset by position control with respect to the polishing cloth rotating the dressing tool After feeding, dressing the polishing cloth, and starting the dressing, the current value supplied to the electric motor that drives the dressing head rises and then begins to decrease until the preset preset value A dressing method characterized by terminating dressing when the temperature falls. 7. A dressing time is measured every time, the dressing time is compared with a preset reference dressing time, and when the dressing time exceeds the reference dressing time, the life of the dressing tool is determined. The dressing method according to claim 6, wherein the dressing tool is replaced after the judgment. 8. The dressing method according to claim 7, wherein a dressing rate of a standard dressing tool serving as a reference is measured in advance, and a reference dressing time is set based on the dressing rate.