JPH07299731A - Wafer polishing device and dressing method for polishing surface - Google Patents

Abstract

PURPOSE:To provide a wafer polishing device and a method for dressing a polishing surface, with which dull of a polish cloth and surface unevenness are removed certainly and the quality of wafer is enhanced. CONSTITUTION:The method includes a separating means 4 to separate a head 2 from the grinding surface 5a and a dressing pad 21 to be put in pressure contact with the grinding surface 5a when the head 2 is separated from the surface 5a, and thereby the grinding of wafer and the dressing works are conducted independently, and the ground surface of the wafer is prevented from ill affection of the falling objects such as abrasive grains off from the dressing pad 21 owing the dressing works.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus and a polishing surface dressing method for polishing the surface of a semiconductor wafer or the like forming an integrated circuit.

[0002]

2. Description of the Related Art In recent years, semiconductor wafers for manufacturing integrated circuits such as LSIs (hereinafter simply referred to as "wafers") have been polished to have a highly accurate and defect-free surface in accordance with miniaturization of devices. Has come to be required. This polishing mechanism is based on a mechano-chemical polishing method that combines a mechanical element such as fine particle silica and an etching element with an alkaline solution. Therefore, since the properties of the polishing agent and the polishing pad are the main factors that determine the surface condition of the wafer, many improvements have been made in the past. However, recent wafer precision,
In particular, the importance of the polishing apparatus itself is increasing with respect to demands such as improvement in flatness.

FIG. 5 is a view showing the structure of a conventional wafer polishing apparatus 1, wherein reference numeral 2 is a head for holding a wafer 3 and 4 is a head.
Is a swivel arm, and 5 is a platen (polishing plate). The head 2 has a wafer carrier 6 under the head 2, and the wafer 3 is held by the wafer carrier 6 in a horizontal state with the surface to be polished facing downward by vacuum suction. On the other hand, a minute air pressure is supplied to the upper side of the wafer carrier 6 from a pressure air source (not shown), the wafer carrier 6 is displaced downward, and the wafer 3 is pressed against the platen 5.

The head 2 is supported by a revolving arm 4 installed on a base 7 so as to face the upper surface of a platen 5. An air cylinder 8 is installed at the tip of the swivel arm 4, and the head 2 can be slightly moved in the vertical direction by the operation of the air cylinder 8 by being linked to the shaft body 9 of the head 2. There is.

Further, the revolving arm 4 can be rotated in a horizontal plane about a support shaft 4a extending in the vertical direction. As a result, the head 2 provided at the tip of the revolving arm 4 can be swung within the range of being located on the platen 5 as shown by an arrow A in FIG.

A polishing cloth (not shown) is attached to the upper surface of the platen 5, and the polishing cloth is brought into contact with the wafer 3 held by the head 2 during polishing. A rotary shaft 10 is provided at the center of the platen 5,
The rotational force of the drive motor 11 installed on the base 7 is transmitted to the rotary shaft 10 via a power transmission mechanism (not shown), and the platen 5 is horizontally rotated.

The wafer polishing apparatus 1 having such a structure starts its operation with the wafer 3 mounted on the head 2 to supply the polishing agent between the wafer 3 and the polishing cloth of the platen 5, The head 2 is swung with respect to the platen 5. At the same time, the platen 5 and the head 2 rotate clockwise. As a result, the polishing cloth is used evenly without polishing the wafer 3 only at the same position on the platen 5, and uneven polishing due to uneven wear of the polishing cloth is prevented. Then, due to such mutual movement of the head 2, the platen 5, and the swing arm 4, the wafer 3 and the polishing cloth are rubbed with each other via the polishing agent, and the surface of the wafer 3 is polished.

[0008]

By the way, the polishing cloth used in such a conventional polishing apparatus 1 is a non-woven fabric attached to the upper surface of the platen 5. Minute irregularities are formed on the polishing surface 5a in the initial state due to unevenness in the thickness of the cloth itself. In addition, such a polishing cloth may cause uneven distribution of the supplied polishing agent as it is used, or may cause clogging due to the polishing agent or silicon scraps forming the wafer 3. Also, minute irregularities are formed on the polishing surface 5a or the polishing ability is reduced. In these cases, it is necessary to carry out truing or dressing to smooth out irregularities or wash off clogging.

As a conventional method of dressing a polishing cloth, as shown in FIG. 6, a head 2 for supporting a wafer 3 is used.
In addition, a method has been devised in which the dressing pad 12 is provided, the wafer 3 is pressed against the polishing surface 5a for polishing, and at the same time, the dressing pad 12 is pressed against the polishing surface 5a. In this case, for example, the polishing surface 5a has a disk shape that can be horizontally swiveled, and an annular dressing pad 12 is provided around the head 2 that supports the wafer 3.
Then, if the wafer 3 and the dressing pad 12 are brought into pressure contact with each other at a midway position in the radial direction of the polishing surface 5a, the wafer 3 is always brought into contact with the polishing surface 5a dressed by the dressing pad 12. It will be.

However, according to such a dressing method, the polishing surface 5a is smoothed by the dressing pad 12 or the clogging is eliminated, but when the abrasive grains of the dressing pad 12 are peeled off from the dressing pad, the polishing is performed. It is conceivable that the particles may be mixed in the polishing agent as they are and have an adverse effect such as scratching the surface of the wafer 3.

The present invention has been made in view of the above circumstances, and provides a wafer polishing apparatus capable of surely removing clogging and unevenness of a polishing cloth and improving the quality of a wafer. Has an aim.

[0012]

In order to achieve the above-mentioned object, the present invention has a method in which a wafer supported by a head is moved relative to the polishing surface of a polishing platen in a state of being pressed against the polishing surface. In the polishing apparatus that slides by sliding the wafer and supplies the polishing agent between the surface of the wafer and the polishing surface to polish the wafer, the head is provided with a separating means for separating the head from the polishing surface. With
A wafer polishing apparatus has been proposed in which a dressing pad is provided that is brought into pressure contact with the polishing surface of the polishing plate when the head is separated from the polishing surface by the spacing means.

In the above wafer polishing apparatus, the polishing surface is formed in a disk shape that can be horizontally swung, and the separating means is horizontally swiveled around a vertical axis that is arranged radially outward of the polishing surface, and the tip thereof is provided. It is effective that the dressing pad is attached to the swivel arm, and the dressing pad is attached to the swivel arm.

The dressing pad may be attached to the revolving arm via a clutch.

Further, in the dressing method for a polishing surface according to the present invention, a circular surface is supported on a disk-shaped polishing surface for horizontally rotating and polishing a wafer pressed against the surface so as to be horizontally rotatable about its axis. The dressing pad of is arranged in an eccentric state, the dressing pad is pressed against the polishing surface over a wider area than the area where the wafer is pressed, and the dressing pad is rotated while the dressing pad is swung to perform dressing. .

[0016]

According to the wafer polishing apparatus of the present invention, the wafer supported by the head is slid on the polishing surface of the polishing plate via the polishing agent, and the surface is polished. As a result, the polishing agent or the shavings of the wafer are attached to the polishing surface.However, by operating the separating means and pressing the dressing pad against the polishing surface with the wafer retracted from the polishing surface, Dressing is performed. In this case, since the wafer is not polished at the same time as the dressing, the abrasive grains and the like peeled off from the dressing pad due to the dressing are not mixed in the polishing agent, and the deterioration of the wafer quality can be prevented.

Further, if the separating means is a swivel arm that is swung horizontally around a vertical axis arranged radially outward of a disk-shaped polishing surface that can be swung horizontally and has a head attached to the tip, By horizontally moving the head around the vertical axis, the wafer is moved away from the polishing surface. If the dressing pad is attached to the swivel arm, the dressing pad is swung horizontally along with the horizontal swiveling of the swivel arm and is placed on the polishing surface, so that the dressing of the polishing surface can be performed. .

Further, if the clutch is provided between the dressing pad and the swing arm, the dressing pad is separated from the polishing operation of the wafer by the swing arm, and the clutch is operated as necessary. As a result, since the swivel arm and the dressing pad can be interlocked with each other, the dressing pad can be dressed on the polishing surface to perform dressing on the polishing surface.

Further, according to the method of dressing a polishing surface according to the present invention, a circular dressing pad rotatably supported horizontally is eccentric to a disk-shaped polishing surface which is horizontally swung. By pressing the dressing pad, the dressing pad is swung around based on the imbalance of the frictional force between the polishing surface and the dressing pad.
As a result, the dressing pad and the polishing surface are slid relative to each other, and the polishing surface is dressed by the dressing pad during the sliding operation.
In this case, the dressing pad is pressed against the polishing surface over a wider area than the area where the wafer is pressed, so that the polishing surface of the portion where the wafer is to be polished is dressed without omission and the wafer is properly polished. It becomes possible to do.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a wafer polishing apparatus and a polishing surface dressing method according to the present invention will be described below with reference to FIGS. Note that the same reference numerals are given to the portions having the same configuration as the conventional example shown in FIGS. 5 to 7, and the description will be simplified.

The wafer polishing apparatus 20 of this embodiment is equipped with a dressing apparatus 22 having a disk-shaped dressing pad 21 that is brought into pressure contact with the polishing surface 5a of the platen 5. The dressing device 22 includes a dressing arm 23 that is arranged to be rotatable about a vertical axis 4 a that is the center of rotation of the rotating arm 4 (separating means), and a dressing pad 2 that is arranged horizontally at the tip of the dressing arm 23.
1 and a cylinder 24 for vertically moving the dressing pad 21.

A clutch 25 is provided between the dressing arm 23 and the revolving arm 4 for connecting and disconnecting them. The clutch 25
By the operator or the wafer polishing apparatus 20.
It is turned on / off by an internal signal or the like, and the dressing arm 23 and the turning arm 4 can be appropriately connected or disconnected. The type of the clutch 25 is not particularly limited, and various types such as mechanical type and electromagnetic type can be applied.

As shown in FIG. 3, the dressing pad 21 is formed in a circular shape having a U-shaped cross section, and along its outer edge, a ring-shaped pressure contact surface 21a to be pressed against the polishing surface 5a. It is equipped with. The pressure contact surface 21a has, for example, a diamond abrasive grain 21 of about 100 mesh.
b is electrodeposited in a uniform distribution state.

The diametrical dimension of the dressing pad 21 is formed to be equal to the radial dimension of the platen 5 in the example shown in FIG. By disposing the outer periphery of the platen 5 at a position inscribed in the outer periphery of the platen 5, the entire polishing surface 5a can be dressed only by rotating the platen 5.

In the cylinder 24, a rod 24a having a dressing pad 21 attached to its tip is projected downward to move the dressing pad 21 in the vertical direction, and the press contact surface 21a is attached to the polishing surface of the platen 5. It can be pressed against the 5a.
For example, the dressing pad 21 is horizontally rotatably attached to the rod 24a, and when the pressing surface 21a is brought into pressure contact with the polishing surface 5a, the dressing pad 21 can be rotated along with the operation of the polishing surface 5a. ing.

The wafer polishing apparatus 20 having the above structure
In order to carry out the polishing work of the wafer 3 by using, the operator first attaches the wafer 3 to the head 2 and a polishing agent composed of an alkaline solution such as potassium hydroxide containing abrasive grains made of fine particle silica. Is poured between the wafer 3 and the polishing cloth of the platen 5, and the head 2 and the platen 5 are moved relative to each other.

That is, as shown in FIG. 1, the platen 5
And the head 2 is rotated clockwise,
The turning arm 4 that supports the head 2 is rotated around the support shaft 4a. Then, while the head 2, the platen 5, and the swivel arm 4 perform such mutual movements, the wafer 3 is rubbed against the polishing surface 5a of the platen 5 via an abrasive, and the surface thereof is polished. Become. At this time, the clutch 25 is turned off, and the turning arm 4 and the dressing arm 23 are disengaged.

Next, the clutch 25 is operated by an operator or an internal signal of the wafer polishing apparatus 20.
When is turned on, the revolving arm 4 and the dressing arm 23 are interlocked and horizontally revolved. The pressure contact surface 21a of the dressing pad 21 provided at the tip of the dressing arm 23 is arranged on the platen 5, and the dressing work is started by being pressed against the polishing surface 5a of the platen 5 by the operation of the cylinder 24. .

In this dressing work, for example, when the polishing work of the wafer 3 is completed, the wafer 3 is subjected to the platen 5
To the outside of the wafer (position indicated by the chain line in FIG. 1)
It is carried out when the replacement work is performed. That is, during the replacement work of the wafer 3, there is a dead time in which the wafer 3 cannot be polished, so the dressing surface 5a is dressed by effectively utilizing this dead time.
At the time of dressing, pure water is sprayed onto the platen 5 to wash away foreign matters such as dust on the wafer swept from the polishing cloth.

Therefore, the wafer polishing apparatus 2 of this embodiment
According to No. 0, since the wafer 3 is moved away from the polishing surface 5a of the platen 5 and the pressing surface 21a of the dressing pad 21 is pressed against the polishing surface 5a to perform the dressing operation, the diamond may be peeled off by the dressing. It is possible to prevent the abrasive grains 21b and the like from mixing with the polishing agent used when polishing the wafer 3. That is, since the polishing work of the wafer 3 and the dressing work with the dressing pad 21 are performed separately, adverse effects such as damage to the surface to be polished of the wafer 3 can be avoided and the quality of the wafer 3 can be improved. .

Further, since the head 2 and the dressing pad 21 can be replaced by a single drive source by rotating the dressing arm 23 in conjunction with the rotating arm 4, the apparatus structure can be simplified. You can Moreover, by the method of performing the dressing work with the wafer 3 removed from the platen 5, the dressing work can be performed by effectively utilizing the dead time when exchanging the wafer 3.

Further, by attaching the dressing arm 23 to the revolving arm 4 via the clutch 25,
The dressing pad 21 can be arranged on the polishing surface 5a of the platen 5 in accordance with the turning operation of the turning arm 4 with the clutch 25 in the ON state, and when the dressing work is not performed, the clutch 25 can be turned into the OFF state. For example, the turning arm 4 and the dressing arm 23 can be separated. As a result, it is possible to prevent an excessive load from acting on the swivel arm 4 during the polishing work and to carry out the smooth polishing work.

Further, according to the method of dressing a polishing surface according to the present invention, the polishing surface 5a of the platen 5 which is horizontally swiveled and the dressing pad 21 which is horizontally rotatably provided are arranged at eccentric positions. The dressing pad 21 is rotated along the rotational movement of the polishing surface 5a by the balance of the frictional force acting non-uniformly over the entire pressure contact surface 21a. Thereby, without requiring a special drive source for the dressing pad 21,
In addition, dressing of the polishing surface 5a can be performed without applying an excessive force to the dressing arm 23.

Since the dressing pad 21 is pressed against the entire polishing surface 5a so as to cover the area on the polishing surface 5a with which the wafer 3 is brought into contact, the polishing surface 5a for polishing the wafer is Dress surely,
The quality of the wafer 3 can be improved.

The wafer polishing apparatus 20 according to this embodiment.
In the above, the dressing pad 21 is formed in a circular shape, but the shape is not limited to this and may be any shape. Further, although the dressing pad 21 is rotated following the rotation of the polishing surface 5a, it may be rotated independently by, for example, attaching a drive motor. Further, although the revolving arm 4 and the dressing arm 23 are connected via the clutch, instead of this, they may be fixed at an appropriate angle, for example, about 90 °.

Further, in the dressing method for the polishing surface 5a according to the present embodiment, the diameter dimension of the dressing pad 21 is made to coincide with the radial dimension of the polishing surface 5a, and the dressing pad 21 is arranged at a position inscribed on the outer periphery of the polishing surface 5a. However, the radial dimension and the center position are not limited to this. That is, it may be arranged so as to cover at least the region where the wafer 3 is brought into pressure contact.

For example, in the example shown in FIG. 4, the diameter of the dressing pad 21 is D _D , the diameter of the platen 5 is D _P , the width of the pressure contact surface 21a is W, and the center of the dressing pad 21 is provided. The diameter of the removed portion 5b is d
In this case, it is preferable to set D _P / 2 ≦ D _D ≦ D _P / 2 + d / 2 + W. As a result, the polishing surface 5
By effectively utilizing a, the dressing pad 21 can be arranged so as not to reduce the swinging speed of the dressing pad 21 and to completely cover the contacted area of the wafer 3.

[0038]

As described in detail above, the wafer polishing apparatus according to the present invention has a separating means for separating the head from the polishing surface and a polishing surface of the polishing plate when the head is separated from the polishing surface. Since the dressing pad that is brought into pressure contact is provided, the wafer polishing operation and the dressing operation by the dressing pad are performed separately, and it is possible to prevent the fine powder of the scraped dressing pad from being mixed with the polishing agent. . As a result, there is an effect that the surface to be polished of the wafer can be finished with high accuracy.

Further, in the above-mentioned wafer polishing apparatus, the polishing surface is formed in a disk shape that can be horizontally swung, and the separating means is horizontally swiveled around a vertical axis arranged radially outward of the polishing surface. A head is attached to the swivel arm, and a dressing pad is attached to the swivel arm. The dressing pad is horizontally swung in conjunction with the swivel arm, and the head and the dressing pad can be replaced with a simple configuration. You can As a result, the polishing work and the dressing work can be separately performed to manufacture a highly accurate wafer, and the dressing work can be performed by effectively utilizing the dead time such as the wafer replacement work. Produce an effect.

Further, by attaching the swivel arm and the dressing pad through the clutch, in addition to the above effect, the dressing pad during the polishing operation is separated from the swivel arm, and the load of the dressing pad is horizontally swung by the swivel arm. The effect that it can avoid working is produced.

According to the method of dressing a polishing surface according to the present invention, a circular dressing pad rotatably supported horizontally is arranged in an eccentric state with respect to the polishing surface, and is wider than a region where a wafer is pressed. The dressing pad is pressed against the entire range and is rotated while the dressing pad is rotated by the rotation of the polishing surface.Therefore, the dressing pad is smoothly rotated by the balance of the frictional force generated between the dressing pad and the polishing surface. Thus, the polishing surface can be satisfactorily dressed without exerting an unreasonable force on the mechanism for supporting the dressing pad. Since the dressing pad performs dressing over a wide range covering the polishing surface to which the wafer is pressed, it is possible to improve the quality of the wafer by bringing the dressed polishing surface into contact with the wafer. it can.

[Brief description of drawings]

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

FIG. 2 is a side view of the wafer polishing apparatus of FIG.

3 is a vertical sectional view showing a dressing pad of the wafer polishing apparatus of FIG.

FIG. 4 is a plan view for explaining the arrangement of the dressing pad of FIG.

FIG. 5 is a vertical sectional view showing a conventional example of a wafer polishing apparatus.

FIG. 6 is a vertical cross-sectional view illustrating a conventional example of dressing a polishing cloth.

7 is a plan view for explaining the operation of each part of the wafer polishing apparatus of FIG.

[Explanation of symbols]

 2 head 3 wafer 4 swivel arm (separating means) 5 platen (polishing plate) 5a polishing surface 20 wafer polishing device 21 dressing pad 25 clutch

Claims (4)

[Claims] 1. A wafer supported by a head is slid by relatively moving the head and the polishing surface in a state of being pressed against the polishing surface of a polishing disk, and at the same time, the surface of the wafer and the polishing surface are moved. In a polishing apparatus for polishing a wafer by supplying a polishing agent between the heads, the head is provided with a separating means for separating the head from the polishing surface, and the head is separated from the polishing surface by the separating means. A wafer polishing apparatus, further comprising: a dressing pad that is brought into pressure contact with a polishing surface of a polishing plate. 2. The polishing surface is formed in the shape of a disk that can be horizontally swung, and the separating means is horizontally swiveled around a vertical axis that is arranged radially outward of the polishing surface, and the head is attached to the tip. 2. The wafer polishing apparatus according to claim 1, wherein the wafer polishing apparatus comprises an arm, and the dressing pad is attached to the swing arm. 3. The wafer polishing apparatus according to claim 2, wherein the dressing pad is attached to the revolving arm via a clutch. 4. A circular dressing pad, which is horizontally rotatably supported around an axis, is eccentrically arranged on a disk-shaped polishing surface for polishing a wafer which is horizontally rotated and pressed against the surface of the wafer. A dressing method for a polishing surface, wherein a dressing pad is pressed against a polishing surface over a wider area than the area to be pressed, and the dressing pad is rotated while the dressing pad is rotated.