JPH10550A - Abrasive cloth dressing method and its device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve flatness by finding the most favourable condition in the case of carrying out dressing of an abrasive cloth by using a dresser grinding wheel having an outside diameter smaller than width of a use region of the abrasive cloth and eliminating nonuniformity of dressing quantity of the abrasive cloth after dressing. SOLUTION: Dressing of an abrasive cloth 1 is carried out so that sliding distance distribution of a dresser grinding wheel 2 at each position in the radial direction within a use region of the abrasive cloth 1 is uniformed while giving rotational motion to the abrasive cloth 1 by giving reciprocal motion in the radial direction of the abrasive cloth 1 to the use region while pressing the circular dresser grinding wheel 2 having an outside diameter smaller than width of the annular use region of the abrasive cloth 1 on the abrasive cloth 1 fixed on a rotating surface plate 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a dressing method for a polishing cloth used in a polishing process for polishing a workpiece while pressing the workpiece against a polishing cloth mounted on a rotary platen to create a flat surface on the workpiece. More particularly, the present invention relates to a polishing cloth dressing method for correcting the shape of a polishing cloth using a small-diameter circular grindstone and a device therefor.

[0002]

2. Description of the Related Art In recent years, it has been particularly required to carry out a polishing process while maintaining a high degree of flatness, for example, in a polishing process of a semiconductor wafer. When a flat surface is created on a workpiece by a polishing apparatus used for such ultra-precision polishing, the flatness of the platen facing in parallel with the processing surface of the workpiece is excellent, and the flatness of the workpiece is high. It is necessary to increase.

In this type of polishing, the flatness of the surface plate gradually deteriorates because the surface plate itself is also polished by the abrasive. For this reason, in order to maintain the flatness of the surface plate, it is necessary to appropriately correct the shape using a grindstone.

[0004] Although the importance of dressing for correcting the flatness of the surface plate has been conventionally recognized, the shape of the surface plate is currently corrected by an empirical method. For example, for a surface plate used for lapping, which is a type of polishing, a correction ring containing a workpiece is placed on the surface plate to correct the shape deterioration, and the flatness of the lap is corrected while processing. ("Precision finishing and special processing", Meidensha 1987, pp. 98-90).

[0005] Among the polishing apparatuses, elastomers, soft plastics, fabrics in which fibers are regularly woven, or
In a polishing apparatus that performs polishing by attaching a polishing cloth made of a nonwoven fabric or the like to a surface plate, it is necessary to appropriately dress the polishing cloth to correct its shape. However, at present, this type of polishing cloth is at the stage of finding the conditions of shape correction through trial and error, and at present, there is no established technology for the method of shape correction at present. is there.

The inventor of the present invention has been studying a method for correcting the shape of the polishing pad, and has been studying the best conditions for further improving the flatness of the polishing pad after dressing. Has a close relationship with the sliding distance distribution of the grindstone sliding on the polishing cloth.

In the process of dressing a polishing cloth while giving a rotation to a circular whetstone and applying a rotating motion to the polishing cloth on a rotary platen in the same direction as the whetstone, the processing mechanism uses a whetstone in the same manner. It is considered that this is basically different from the grinding of metal and hard brittle material. In the grinding of metals and hard and brittle materials, the processing amount and processing shape are determined by the cutting amount of the grindstone, whereas the polishing cloth is soft,
This is because the processing amount and the processing shape do not correspond to the cutting amount of the grinding stone because the grinding stone is elastically deformed by being pressed.

Conventionally, regarding dressing of a polishing cloth,
The fact that the processing conditions had to be determined empirically by trial and error is considered to be based on the characteristics of this polishing cloth processing.

In general, in polishing, it is said that there is a strong correlation with the amount of processing, the surface pressure between the workpiece and the polishing platen and the distance over which the grindstone slides on the surface of the polishing cloth. Actually, the contact pressure and the sliding distance and the processing amount are usually not proportional to the crushing or deterioration of the abrasive, but in the dressing of a polishing cloth to which a grindstone is applied as in the present invention, ,
Since the processing action is given by a grindstone that is less likely to be crushed or deteriorated than the abrasive, it is expected that the surface pressure and the processing amount, and the sliding distance and the processing amount are almost proportional to each other. Further, in the present invention, since it can be assumed that the grindstone is pressed against the polishing cloth with a constant surface pressure, the shape of the polishing cloth after dressing is mainly determined by the sliding distance distribution of the dresser at each point of the polishing cloth. it is conceivable that.

The present inventor simulated dressing conditions and mechanical conditions such as the size of a polishing cloth and a dresser grindstone for optimizing a dressing shape and a control range of a rotation speed. As a result, using a ring-shaped dresser grindstone having an inner diameter equal to or larger than the width of the use area of the polishing cloth, pressing while rotating the polishing cloth, the same as the dresser grindstone on the polishing cloth fixed on a rotating platen. When dressing the polishing cloth while giving a rotational motion of a predetermined number of rotations in the direction, although there is a feature that the amount of dressing can be increased and the time required for dressing can be shortened.
In order to improve the flatness of the dressing shape, it is necessary to use a polishing cloth having a relatively large diameter as compared with the width of the used area of the polishing cloth.

[0011]

As a polishing cloth dressing method of this type, there is a method using a small-diameter dresser grindstone in addition to the above-described large-diameter dresser grindstone. If the outside diameter of the small-diameter dresser grindstone is smaller than the width of the used area of the polishing cloth, dressing must be performed while reciprocating the dresser grindstone in the radial direction. In fact, dressing conditions such as speed rely on empirical intuition, and there is no technology that has established objectively optimal processing methods.

Accordingly, an object of the present invention is to solve the above-mentioned problems of the prior art, and to provide the best case for dressing a polishing cloth using a dresser whetstone having an outer diameter equal to or less than the width of a use area of the polishing cloth. An object of the present invention is to provide a polishing cloth dressing method and an apparatus therefor which find out the conditions, eliminate non-uniformity of the dressing amount of the polishing cloth after dressing, and improve the flatness.

[0013]

FIG. 3 shows a method of dressing an abrasive cloth while moving a small disk-shaped dresser grindstone in the radial direction according to the present invention. It is a schematic explanatory view showing the positional relationship of the exercise with. In this figure, 1 is a polishing cloth and 2 is a dresser grindstone. The rotation center of the polishing pad 1 is O ₁ , and the polishing pad 1 is stuck on a surface plate and rotates at a rotation speed N ₁ . In this case, the dresser grindstone 2 is a rotational speed N ₂ is rotated in the same direction the rotation center as O _2.

The radius of the polishing cloth 1 is R. Of these, the area indicated by the meshes in FIG. 3 is an area actually used in polishing, and is a concentric area having a width W in the radial direction. . In the dressing method according to the present invention, the width W
Is used to shape the use area. A is the distance from the center O ₁ of the polishing pad ₁ to the center position O of the use area. Note that Do is the diameter of the dresser whetstone 2. In the dressing method of the present invention, the dresser whetstone 2 to be used has a diameter smaller than the width of the used area of the polishing pad 1.

In the conventional dressing method using a dresser grindstone having a diameter smaller than the used area width, the quality of the final dressing shape largely depends on experience. In contrast, the present inventor has found that the sliding distance of the dresser grindstone at each point of the polishing cloth is closely related to the dressing amount, and by utilizing this,
The purpose of this study was to obtain the sliding distance distribution of the dresser grindstone and to try to optimize the swinging and moving conditions of the dresser grindstone.

For example, FIG. 4 shows that the maximum sliding distance of the dresser whetstone in the portion of the use area of the polishing cloth is 1, and the horizontal axis indicates the use area within the range of ± W / 2 from the center O of the use area of the polishing cloth. Are taken in the radial direction, and the ratio of the sliding distance at each position is graphed. In FIG. 4, the vertical axis is shown upside down,
Assuming that the sliding distance is proportional to the dressing amount, the characteristics of the distribution of the sliding distance correspond to the cross-sectional shape of the dressing cloth after dressing.

As a result of dressing the polishing cloth under the same conditions using an actual polishing apparatus, the cross-sectional shape of the actual polishing cloth after dressing is in good agreement with the hatched portion in the graph of FIG. It was confirmed that it is effective to obtain the sliding distance distribution in the dressing shape prediction evaluation.

The polishing cloth dressing method according to the present invention comprises:
Based on such knowledge, the feature of the polishing is that a circular dresser whetstone having an outer diameter smaller than the width of the annular use area of the polishing cloth is fixed on a rotary platen. The sliding distance of the dresser whetstone at each radial position in the working area of the polishing cloth while giving a reciprocating motion in the polishing cloth radial direction to the working area while pressing against the cloth, and giving the polishing cloth a rotational movement. To dress the polishing cloth so that the distribution is uniform,
More preferably, the reciprocating movement width represented by the outer diameter of the dresser grindstone, the width of the polishing cloth used area, and the width of the outer diameter of the dresser grindstone plus the outer diameter of the dresser grindstone in and out in the radial direction of the polishing cloth or more, The dressing of the polishing cloth is performed within a range not more than the radius value of the polishing cloth.

As the dresser grindstone, a disk-shaped dresser or a ring-shaped dresser is used. In the disk-shaped dresser, the amount of movement of the disk-shaped dresser per rotation of the polishing cloth in the radial direction of the polishing cloth is changed. It is preferable that dressing of the polishing pad is performed by reciprocating the disc-shaped dresser so that the outer diameter becomes 1/4 or less.

In the ring-shaped dresser, the amount of movement of the ring-shaped dresser per rotation of the polishing cloth in the radial direction of the polishing cloth is １ ／ of the outer diameter of the dresser or the width of the dresser grindstone, whichever is smaller. It is preferable to dress the polishing cloth by reciprocating the ring-shaped dresser as described below.

An apparatus for carrying out such a polishing cloth dressing method according to the present invention comprises a rotating platen on which a polishing cloth to be dressed is mounted and which rotates at a constant rotational speed, and an annular use area of the polishing cloth. A dresser grindstone having a circular outer diameter smaller than the width of the dresser, a dresser rotating means for holding the dresser grindstone and performing a rotational motion at a predetermined rotation speed, and applying the dresser grindstone to the polishing cloth at a predetermined surface pressure. A dresser moving means for reciprocating in the radial direction of the polishing cloth while pressing, and a reciprocating movement controlling means for controlling a moving amount and a moving speed of the reciprocating movement of the dresser grindstone are provided.

As the dresser moving means, a swinging mechanism having the dresser rotating means attached to one end and having a swing arm swinging in the radial direction of the polishing pad, or the dresser rotating means is linearly moved in the radial direction of the polishing pad. It is preferable to use a linear movement mechanism that reciprocates.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a polishing cloth dressing method and apparatus according to the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows an apparatus for carrying out a polishing cloth dressing method according to the present invention. In this FIG.
1 denotes a polishing cloth and 2 denotes a dresser whetstone.

The polishing cloth 1 is a polishing cloth made of, for example, an elastomer, a soft plastic, or a woven or non-woven fabric in which fibers are regularly knitted, and is attached to a concentric position on the upper surface of the rotary platen 3 using an adhesive or the like. It can be attached. The rotary platen 3 is connected to a rotary drive mechanism incorporated in a machine base (not shown).

On the other hand, a dresser grindstone 2 for correcting the shape of the deteriorated polishing pad 1 is a disc-shaped or ring-shaped grindstone, and is held by a dresser rotating head 4 constituting dresser rotating means. I have. The rotation speed of the rotating platen 3 and the dresser grindstone 2 can be set and controlled to an arbitrary rotation speed by a control device (not shown). Note that this control device includes a swing mechanism 5
The reciprocating width and the moving speed of the reciprocating motion of the dresser grindstone, which will be described later, can be controlled by controlling the number of rotations of the rocker.

The dresser rotating head 4 is attached to one end of a swing arm 6 constituting the swing mechanism 5, and the other end of the swing arm 6 is connected to a dresser elevating mechanism 7 via a turning motor. Are linked. Therefore, at the time of dressing the polishing cloth 1, the dressing whetstone 2 is
Is pressed against the polishing pad 1 with an appropriate surface pressure. that time,
The dresser grindstone 2 is reciprocated in a radial direction across the range including the use area of the polishing pad 1 shown in FIG. 3 with the swing of the swing arm 6 while being given a rotational movement by the dresser rotating head 4. It can slide and scrape its top surface.

At the time of dressing, the polishing cloth 1 is usually given rotational motions N ₁ and N _{2 in the} same direction as the dresser whetstone 2. The swing mechanism 5 rotates the swing arm 6 in a direction away from the rotary platen 2 while the dresser grindstone 2 is not used, so that the dresser grindstone 2 does not contact the polishing cloth 1. Is to be evacuated.

Next, FIG. 2 shows that the dresser whetstone 2 is
FIG. 4 is a diagram showing an embodiment of a dressing device using a linear moving mechanism that makes a linear reciprocating motion in the radial direction of the dressing device. This dressing device includes a linear reciprocating mechanism 8 instead of the swing mechanism 5 in FIG. 1. In the linear reciprocating mechanism 8, the lower surface of the cross beam 9 has guide grooves 10 in the length direction. A carriage 11 for holding the dresser rotary head 4 via a dresser elevating device 12 is slidably fitted in the guide groove 10. The carriage 11 is reciprocated by a linear driving device (not shown), so that the dresser whetstone 2 linearly reciprocates on the polishing cloth within a range including the use area of the polishing cloth 1.

In the dressing apparatus shown in FIG.
The cross girder 9 is configured to be pivotable, and at the time of dressing, the cross girder 9 is positioned exactly at a position extending in the radial direction of the polishing cloth 1, and the direction of the reciprocating motion of the dresser whetstone 2 is adjusted to the radial direction of the polishing cloth 1. It is going to be the same.

Next, as an embodiment of the dressing method of the present invention, the results of a simulation of dressing a polishing pad with the above-described apparatus under various processing conditions and various conditions will be described. This will be described in detail.

FIGS. 5 and 6 show the center O of the dresser whetstone 2.
The sliding distance distribution of the dresser whetstone 2 when the polishing cloth 1 was dressed without giving a reciprocating motion in the radial direction by making ₂ (see FIG. 3) coincide with the center O of the working area width of the polishing cloth 1 was simulated by computer. It is a figure showing a result. Among them, FIG. 5 shows a case where a disc-shaped dresser is used for the dresser grindstone 2, and FIG. 6 shows a case where a ring-shaped dresser is used.
In each case, the dresser outer diameter Do (see FIG. 3) is 40 mm.

In these figures, the vertical axis shows the ratio of the maximum value and the minimum value of the sliding distance to 0 at the uppermost part and becomes larger as it goes downward, and the vertical axis shows the ratio of the polishing cloth after dressing. Shape, that is, the characteristics of the dressing shape.

In the case of a disk-shaped dresser whose outer diameter Do is smaller than the width W of the working area of the polishing cloth 1, unless the reciprocating motion is applied in the radial direction of the polishing cloth 1, the polishing cloth is slightly located from the center O of the width W of the working area. It can be seen that there is a feature that the cutting is deepest at a position closer to the center of No. 1.

When a ring-shaped dresser is used, the dressing amount is set at the center O within a range on both sides of the center O of the used area width W.
It can be seen that there is a characteristic of decreasing toward.

Next, in simulating the sliding distance distribution of the dresser, the dressing shapes obtained in FIGS. 5 and 6 were numerically modeled. FIG. 7 illustrates this. Among these, FIG. 7A is a model in which the dressing shape in the case of using a disk-shaped dresser is simplified by four rectangles, and FIG. 7B is a simplified model of a ring-shaped dresser. . Here, the amount that the dresser grindstone 2 moves in the radial direction of the polishing cloth 1 per rotation of the polishing cloth 1 is set to a value corresponding to the width of each rectangular area, and four times the width is defined as the outer diameter of the dresser grindstone 2. Has become. The vertical size of each rectangular area represents the ratio to the maximum sliding distance of 10, and FIGS. 7A and 7B approximate the sliding distance distributions of FIGS. 5 and 6, respectively. It is a quantity model.

Next, the dressing is performed until the dresser whetstone 2 returns to the original position by making a reciprocating motion once in a range equivalent to five times the outer diameter of the dresser using the quantity model of the dressing shape. FIG. 8 shows the results obtained by numerical evaluation.

8A shows the case of the disk-shaped dresser model of FIG. 7A, and FIG.
This is the case of the ring dresser model of FIG.

For example, in FIG. 8A, the sliding distance is 6, 10, 9, 5 at the initial position, and 10 + 6, 9 + 10,
Since the sliding distance is increased by 8 + 9,5, if the sliding distance is considered to be proportional to the dressing amount, the overall dressing amount during one reciprocation of the dresser in the radial direction becomes vertical for each position. The numerical value is the numerical value at the bottom of the figure, and this numerical value is a value corresponding to the dressing amount of each part of the polishing cloth for the final dressing shape by the disk-shaped and ring-shaped dressers.

From this result, in the range of the reciprocating motion, in a region three times the outer diameter of the dresser on both sides from the center of the reciprocating motion,
It can be seen that while the integrated value of the sliding distance is uniform, that is, the dressing is uniform, there is a non-uniform portion having a variation in the dresser outer diameter equivalent regions on both the left and right sides of the uniform region.

FIGS. 9 (a) and 9 (b) show the sliding distance distribution when dressing with a reciprocating width of 270 mm for each of a disk-shaped dresser and a ring-shaped dresser having an outer diameter of the dresser whetstone 40 mm. Is shown. In this case, for one cycle until the dresser whetstone 2 returns to the same positional relationship as at the start of dressing, for a disk-shaped dresser, for four cross sections orthogonal to the rotation center, for a ring-shaped dresser,
The simulation is performed on a cross section in which the direction is changed by 30 ° at a time.

According to the results of this simulation, on both the left and right sides of the reciprocating width, non-uniform sliding distance portions occur in the range (-135 to -95, +95 to +135) corresponding to the dresser outer diameter. On the other hand, the center is a substantially uniform portion, and it can be seen that the result matches the result of the model of FIG. 8 described above.

From the above results, the width of the reciprocating motion of the dresser grindstone 2 is set to be equal to the width W of the polishing area 1 in the radial direction of the polishing area 1 in order to make the dressing amount of the polishing area 1 uniform. It can be seen that the width needs to be added to the inside and outside plus a margin greater than the outside diameter of the dresser. However, the upper limit of the reciprocating movement width is also restricted by the radius of the polishing pad 1.

The above is an analysis result on the relationship between the use area of the polishing pad 1 and the reciprocating motion width of the dresser whetstone 2.
Next, the amount of movement of the dresser grindstone 2 in the radial direction per rotation of the polishing cloth 1 (hereinafter referred to as the amount of dresser movement).
FIG. 10 shows the result of analyzing the relationship between the uniformity of the dressing amount and the simulation by simulation.

Here, the uniformity represented by the vertical axis in each figure of FIG. 10 is represented by a uniformity index δ calculated from the following equation, and the sliding distance distribution obtained by computer simulation. The maximum value of the sliding distance L among the unevenness of the curve
And the ratio of the difference between the minimum value S and the minimum value S. δ = (LS) / L Assuming that the sliding distance and the dressing amount are in a proportional relationship, the smaller the value of the uniformity, the better the flatness of the dressing portion of the polishing pad 1 is. This shows that a dressing shape is created.

In each of FIGS. 10A and 10B, the horizontal axis represents the movement pitch, which is a dimensionless number obtained by dividing the dresser movement amount by the dresser outer diameter value. This is because the dresser movement amount is a relative amount determined by the relationship with the outer diameter of the dresser grindstone.

FIG. 10 (a) shows the uniformity value of the disk-shaped dresser simulated with the movement pitch indicated by the value shown on the horizontal axis. On the other hand, FIG.
0 (c) and FIG. 10 (d) show the results of a simulation for a ring-shaped dresser. In the case of this ring-shaped dresser, it is necessary to consider the width of the grindstone with respect to the outer diameter. The ratio of the outer diameter is 1/4, 1/8,
The relationship with the uniformity was simulated for ring dressers of each size of 3/40.

First, from FIGS. 10 (a) and 10 (b), in the case of a disc-shaped dresser and a ring-shaped dresser having a relatively large grindstone width, the dresser moving amount is set to 1 / moving pitch.
4 or less, in other words, 1 /
It can be clearly seen that the effect of improving the uniformity of the sliding distance distribution becomes remarkable when the moving amount is 4 or less. Further, in the case of a disk-shaped dresser and a ring-shaped dresser having a relatively large grindstone width, the dresser moving amount is set to 1/8 of the moving pitch.
By setting the movement amount to less than or equal to 1/8 of the outer diameter of the dresser, the uniformity can be reduced to about 0.1 or less, that is, the unevenness of the sliding distance distribution shape can be kept within 10%, It turns out that it is particularly effective in improving the flatness of the dressing shape.

Next, FIGS. 10C and 10D show that the grindstone width is relatively small, that is, the grindstone width is 1 / the outer diameter of the dresser.
It is the result of having performed the simulation about the case of the ring-shaped dresser which is less than four. In such a dresser, since the width of the grindstone is smaller than 1/4 of the outer diameter of the dresser, which is the appropriate range of the amount of movement of the dresser, the dimensional effect of the grindstone width is likely to be remarkable. From FIG. 10 (c),
Even if the moving amount is 1/4 of the dresser outer diameter, if the grindstone width is 1/8 smaller than this, the effect of improving the uniformity is not so much improved, and the moving amount is the same as the dresser outer diameter. It can be seen that when １ ／ is set, the uniformity of the sliding distance distribution can be 0.1 or less, that is, the unevenness can be made within 10%. Similarly, from FIG. 10 (d), the grindstone width is 3 times the dresser outer diameter.
In the case of / 40, the improvement of the uniformity of the sliding distance distribution becomes remarkable when the dresser movement amount is 3/40 of the dresser outer diameter which is the same as the grindstone width.

In summary, in the case of a disk-shaped dresser, the effect of improving the uniformity of the sliding distance distribution, that is, the improvement of the flatness of the dressing shape is that the movement amount of the tressa is 1/1 / the outer diameter of the dresser. 4 or less, and particularly effective when the dresser movement amount is 1/8 or less of the dresser outer diameter. In the case of a ring-shaped dresser, when the dresser moving amount is set to be equal to or less than １ ／ of the dresser outer diameter or the smaller of the dresser grindstone width, it is effective for uniformity of the sliding distance distribution, and more effective. There is a case where the width is less than 1/8 of the outer diameter of the dresser or the width of the dresser wheel, whichever is smaller.

In actual dressing, the dresser movement amount and the required dressing time have an inverse relationship, so that it is difficult to make the dresser movement amount extremely small.
Dressing efficiency will be reduced. Therefore, as the lower limit value of the moving amount of the dresser, in the case of the disc-shaped dresser, about 1/16 of the outer diameter, and in the case of the ring-shaped dresser, the smaller of 1/16 of the outer diameter or 1/2 of the grindstone width. A value of about one is desirable.

The simulation results on the reciprocating motion width and the movement amount of the dresser grindstone as described above are obtained by swinging the arm of the dresser grindstone as in the apparatus shown in FIG. In the case of applying the linear reciprocating motion to the dresser whetstone by using the apparatus shown in FIG. Unlike the linear reciprocating motion, there is a feature that the component of the dresser moving speed in the polishing cloth radial direction changes depending on the position.

FIG. 11 shows a simulation of the sliding distance distribution by changing the arm length of the swing arm 9 in order to examine the effect of the change in the dresser moving speed in the polishing cloth radial direction on the sliding distance distribution. FIG. 9 is a diagram showing a result obtained. FIG. 11 is a graph in which the horizontal axis represents each position in the width direction of the use area of the polishing cloth, and the vertical axis represents the maximum sliding distance as 1, and the ratio of the sliding distance at each position is taken. 11
FIG. 11A shows a case where the arm length of the swing arm 9 is short.
(B) is a case where the arm length of the swing arm 9 is long.

As is clear from comparison between FIGS. 11A and 11B, when the length of the swing arm 9 is long, the change of the dresser moving speed in the radial direction of the polishing cloth is not affected. It can be seen that the smaller the distance, the more the unevenness of the sliding distance distribution is reduced. Therefore, in order to improve the uniformity of the sliding distance distribution, it is preferable to make the arm length of the swing mechanism as long as possible.

As described above, the longer the arm, the better.
In an actual polishing apparatus, there is a problem that the apparatus becomes large. Therefore, when the reciprocating motion is given to the dresser whetstone by using the swing mechanism, the swing rotation speed is controlled by the swing mechanism control device so that the component of the dresser moving speed in the polishing cloth radial direction is constant. It is preferable to have a function. Thus, the uniformity of the sliding distance distribution, that is, the flatness of the dressing shape can be improved without increasing the overall length of the swing mechanism.

On the other hand, when a linear reciprocating motion is given to the dresser whetstone, and when the moving direction coincides with the polishing cloth radial direction, the speed component of the dresser moving speed in the polishing cloth radial direction is constant, which causes a problem. However, when the moving direction does not coincide with the polishing cloth radial direction, sliding is performed by controlling the moving speed so that the polishing cloth radial component of the dresser moving speed is constant, as in the case of the swing mechanism. The uniformity of the distance distribution can be improved.

[0057]

As is apparent from the above description, according to the present invention, when a dresser grindstone having a diameter smaller than the width of the polishing cloth use area is used, the flatness of the final shape of the polishing cloth is improved. In addition, since dressing can be performed on the polishing cloth under the best conditions, it greatly contributes to improving the precision of ultra-precision polishing.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of a polishing cloth dressing apparatus according to the present invention.

FIG. 2 is a perspective view showing another embodiment of a polishing cloth dressing apparatus according to the present invention.

FIG. 3 is a schematic explanatory view showing a relative positional relationship between movement of a polishing cloth on a rotary platen and a dresser whetstone in the polishing cloth dressing method according to the present invention.

FIG. 4 is a graph showing a distribution of a sliding distance of a dresser whetstone in a portion of a use region of a polishing cloth.

FIG. 5 is a view showing a result of simulating a sliding distance distribution of a dresser grindstone when dressing a polishing pad without giving a reciprocating motion in a radial direction to a disc-shaped dresser grindstone.

FIG. 6 is a diagram showing a result of simulating a sliding distance distribution of a dresser grindstone when dressing a polishing pad without giving a reciprocating motion in a radial direction to a ring-shaped dresser grindstone.

FIG. 7 is a diagram in which a dressing shape is quantitatively modeled for each of a disk-shaped dresser and a ring-shaped dresser.

FIG. 8 is a diagram for numerically evaluating a result of performing dressing by reciprocating once in a range equivalent to five times the outer diameter of the dresser by using the dressing shape quantity model of FIG. 7;

FIG. 9 is a diagram showing a result of simulating a sliding distance distribution for each of a disk-shaped dresser and a ring-shaped dresser.

FIG. 10 is a view showing a result of analyzing by simulation a relationship between a moving amount of a dresser grindstone in a radial direction per rotation of a polishing cloth and uniformity of a sliding distance distribution.

FIG. 11 shows the effect of a change in a dresser moving speed in a polishing cloth radial direction component on a sliding distance distribution when a swing mechanism is used, obtained by simulating the arm length of a swing arm in each case of a long and short arm. The figure which shows a result.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Polishing cloth 2 Dresser grindstone 3 Rotating surface plate 4 Dresser rotating head (dresser rotating means) 5 Swing mechanism 6 Swing arm 7 Dresser elevating mechanism 8 Linear reciprocating mechanism 9 Cross beam 10 Guide groove 11

[Procedure amendment]

[Submission date] July 25, 1996

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0050

[Correction method] Change

[Correction contents]

Summarizing the above, in the case of a disk-shaped dresser, the effect of improving the uniformity of the sliding distance distribution, that is, the improvement of the flatness of the dressing shape is that the amount of movement of the dresser is 1 / the outer diameter of the dresser. 4 or less, and particularly effective when the dresser movement amount is 1/8 or less of the dresser outer diameter. Further, in the case of a ring-shaped dresser, if the amount of movement of the dresser is equal to or less than １ ／ of the outer diameter of the dresser or the smaller of the dresser grindstone width, it is effective for uniformity of the sliding distance distribution, and more effective. There is a case where the width is less than 1/8 of the outer diameter of the dresser or the width of the dresser wheel, whichever is smaller.

[Procedure amendment 2]

[Document name to be amended] Drawing

[Correction target item name] Figure 3

[Correction method] Change

[Correction contents]

FIG. 3

[Procedure amendment 3]

[Document name to be amended] Drawing

[Correction target item name] Fig. 9

[Correction method] Change

[Correction contents]

FIG. 9

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Fumitaka Ito 2068-3 Ooka, Numazu-shi, Shizuoka Pref.

Claims (10)

[Claims] 1. A polishing machine in a polishing cloth radial direction while pressing a circular dresser whetstone having an outer diameter smaller than the width of an annular use area of a polishing cloth against the polishing cloth fixed on a rotary platen. Performing dressing of the polishing cloth so that the sliding distance distribution of the dresser whetstone at each position in the radial direction within the use area of the polishing cloth is uniform while giving the reciprocating movement of the polishing cloth and the rotating movement of the polishing cloth. A polishing cloth dressing method characterized by the above-mentioned. 2. The reciprocating motion width represented by the outer diameter of the dresser grindstone is not less than the width obtained by adding the value of the outer diameter of the dresser grindstone to the use area width of the polishing cloth and the inside and outside of the polishing cloth in the radial direction. The polishing cloth dressing method according to claim 1, wherein the dressing of the polishing cloth is performed within a range equal to or less than a radius value of the polishing cloth. 3. The dresser whetstone comprises a disk-shaped dresser or a ring-shaped dresser.
A polishing cloth dressing method according to item 1. 4. An amount of movement of said disk-shaped dresser per rotation of said polishing pad in a radial direction of said polishing pad is one-fourth of a dresser outer diameter.
The polishing cloth dressing method according to claim 3, wherein the dressing of the polishing cloth is performed by reciprocating the disc-shaped dresser as follows. 5. An amount of movement of said ring-shaped dresser in the polishing cloth radial direction per rotation of said polishing cloth is 1/1 / the outer diameter of the dresser.
4. The polishing cloth dressing method according to claim 3, wherein the dressing of the polishing cloth is performed by reciprocating the ring-shaped dresser so as to be less than a smaller value of 4 or the width of the dresser grindstone. 6. The dressing of a polishing cloth according to claim 3, wherein the dressing is performed while reciprocating the dresser whetstone so that a radial velocity component of the dresser whetstone is constant during the reciprocating movement. Polishing cloth dressing method. 7. A rotating platen on which a polishing cloth to be dressed is mounted and rotates at a constant rotation number; a circular dresser whetstone having an outer diameter smaller than a width of an annular use area of the polishing cloth; Dresser rotating means for holding the dresser grindstone and providing rotational motion at a predetermined rotation speed, and dresser moving means for performing reciprocating motion in the polishing cloth radial direction while pressing the dresser grindstone against the polishing cloth at a predetermined surface pressure, A polishing cloth dressing apparatus, comprising: a reciprocating motion control means for controlling a moving amount of the reciprocating motion of the dresser whetstone and a moving speed. 8. The dresser moving means according to claim 7, wherein said dresser rotating means comprises a swinging mechanism having a swinging arm attached to one end and swinging in a radial direction of the polishing pad. A polishing cloth dressing device. 9. A polishing cloth dressing apparatus according to claim 7, wherein said dresser moving means comprises a linear moving mechanism for linearly reciprocating said dresser rotating means in a radial direction of said polishing cloth. 10. The polishing cloth dressing apparatus according to claim 7, wherein the polishing cloth is a polishing cloth made of an elastomer, a soft plastic, a woven fabric in which fibers are regularly woven, or a nonwoven fabric.