JPH07299738A - Wafer polishing device - Google Patents

Abstract

PURPOSE:To enhance the quality of a wafer by removing dullness of a polishing cloth and surface unevenness uniformly and certainly over a wide scope. CONSTITUTION:A plurality of nozzles 22 jetting an abrasive toward a polish surface 5a are furnished at the periphery of a head 2 in the circumferential arrangement, and thereby the polish surface 5a around the head 2 in relative movement with the polish surface 5a is subjected to a dressing process uniform. The nozzle 22 is put in relative movement to the polish surface 5a in association with the motions of the head 2, and thereby a wide scope of dressing can be achieved.

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 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. 6 is a diagram 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 in a horizontal state with the surface to be polished facing downward by being vacuum-adsorbed by the wafer carrier 6. 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 the platen 5 and can be horizontally rotated in synchronization with the rotation of the 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 swivel 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 to be polished 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 remove the abrasive or the like that smoothes or clogs the irregularities.

As a conventional method of dressing a polishing cloth, as shown in FIG. 7, 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 adversely affect the surface of the wafer 3 to be polished. In order to eliminate such inconvenience, a method of performing dressing by injecting a high-pressure polishing agent from the outside of the polishing surface 5a onto the polishing surface 5a has been devised, but it is not limited to simply using the polishing agent. However, it is difficult to uniformly dress the polishing surface 5a over a wide range.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to improve the quality of a wafer by uniformly and surely removing clogging and unevenness of the polishing cloth over a wide range. The purpose is to provide a polishing apparatus.

[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 for polishing the wafer by supplying the polishing agent between the surface to be polished and the polishing surface of the wafer, the nozzle for ejecting the polishing agent toward the polishing surface is the head. A plurality of wafer polishing devices are provided around the periphery of the wafer along the circumferential direction.

Further, in the above-mentioned wafer polishing apparatus, a head supporting means for laterally supporting the outer peripheral surface of the head is provided around the head, and the head supporting means is spaced in the circumferential direction of the head. A plurality of rolling elements are provided to be rolled on the outer peripheral surface of the head in the circumferential direction, and a ring-shaped support member that rotatably supports the rolling elements by connecting them, and the nozzle is arranged along the support member. It is effective to employ a configuration in which the tubular members that are attached to each other and through which the abrasive is circulated are provided at intervals in the longitudinal direction.

Further, the removing means for removing the head from the polishing surface and the dressing pad which is brought into pressure contact with the polishing surface when the head is removed may be provided.

[0015]

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 to be polished is polished. As a result, the polishing agent or shavings of the wafer adheres to the polishing surface, but since the supplied polishing agent is ejected from the nozzle, the polishing surface is dressed and the shavings are removed. . In this case, since the nozzle is provided in the head which is moved relative to the polishing surface, a wide range of polishing surface is dressed. Further, since a plurality of nozzles are provided in the circumferential direction of the head, the wafer is always polished by the dressed polishing surface regardless of the relative movement direction of the head and the polishing surface.

If the head is supported laterally by the head supporting means, the head can be stably supported by the abrasive sprayed from the nozzle without vibrating. In this case, if a tubular member is arranged along the ring-shaped support member of the head support means and a plurality of nozzles are provided at intervals in the longitudinal direction of the tubular member, the flow and injection of the polishing agent Thus, the reaction force acting on the tubular member can be supported by the support member.

Further, in addition to the dressing work of the polishing surface performed in parallel with the polishing work of the wafer by spraying the polishing agent, when the wafer is removed from the polishing surface by the operation of the removing means, the wafer is pressed against the polishing surface. If the dressing work is performed by using the dressing pad, it becomes possible to more effectively condition the polishing surface.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the wafer polishing apparatus according to the present invention will be described below with reference to FIGS. In each of these figures, reference numeral 30 is a diaphragm for moving the wafer carrier 6 up and down, 31 is a hole provided in the wafer carrier 6 for vacuum suction of the wafer 3, 32 is a retainer for suppressing horizontal movement of the wafer, and 33 is Diaphragm 3
A pressure chamber for displacing 0, 34 is a shaft, 35 is a housing, 36 is a sleeve, 37 is a pulley, 38 is a spline, 39 is a stopper, 40 is a weight, and 41 is a pin. It should be noted that the same reference numerals are given to portions having the same configuration as the conventional example shown in FIGS. 6 to 8 to simplify the description.

As shown in FIGS. 1 and 2, the wafer polishing apparatus 20 of the present embodiment is attracted to the head carrier 21 for laterally supporting the horizontally swiveling head 2 and the wafer carrier 6 of the head 2. A nozzle 22 for spraying a polishing agent is provided between the wafer 3 and the polishing surface 5a of the platen 5, and a dressing pad 23 attached to the swivel arm 4.

The head 2 transmits the rotational force transmitted to the sleeve 36 via the pulley 37 to the shaft body 34 via the spline 38, and causes the shaft body 34 and the head 2 to have a predetermined backlash. It is configured to be horizontally rotated by transmitting it through a pin 41 which has and is coupled. In addition, the head 2 counteracts a reaction force that pushes up the housing 35 when the wafer 3 is pressed against the platen 5 by the minute air pressure supplied to the pressure chamber 33 by the weight 40 mounted on the upper surface of the housing 35. It is designed to be pressed.

Further, a head drive mechanism 43 (pressing means) including an air cylinder 42 installed at the tip of the arm 4 is connected to the shaft body 34 of the head 2, and the head drive mechanism 43 is operated by the operation of the head drive mechanism 43. The head 2 can be slightly moved in the vertical direction. Also,
A head rotating mechanism 44 is provided on the sleeve 36. The head rotating mechanism 44 synchronizes with the platen 5 which is rotationally driven by the drive motor 11 to rotate the head 2 around its axis 2b, so that the pulley 46, the belt 47, the drive shaft 48, the pulley 49, and the belt 50 are rotated. The head 2 and the motor 11 are connected to each other via the like.

Rotational force is transmitted to the arm 4 from an arm driving motor (not shown) via the belt 51, the pulley 52, and the support shaft 53, so that the arm 4 is horizontally rotated within a predetermined range. It has become. This allows the arm 4
Constitute a moving means for horizontally moving the head 2.

The head supporting means 21 is, for example, as shown in FIG.
Further, as shown in FIG. 3, a support member 24 which is rotated together with the swivel arm 4 at a position below the swivel arm 4, and which is attached to the support member 24 and is arranged around the head 2 at equal intervals in the circumferential direction. And three rolling elements 25. The rolling element 25 is, for example, a roller (hereinafter,
Called roller 25. ), And is arranged in contact with the lower portion of the outer peripheral surface 2a of the head 2. Laura 2
5 is attached to a vertical shaft 26 fixed to the support member 24 in a vertically downward protruding state via a bearing (not shown) so as to be horizontally rotatable.

As shown in FIG. 3, a plurality of nozzles 22 are provided in the tubular member 27 arranged along the supporting member 24 of the head supporting means 21 at circumferential intervals. The tubular member 27, as shown in FIG.
5 is arranged in an arc shape, and the polishing agent supplied through a supply pipe 28 connected to a polishing agent supply device (not shown) is circulated therein and the polishing agent is circumferentially spaced. It is designed to be ejected from each nozzle 22 provided.

As shown in FIG. 3, the nozzle 22 has its tip arranged inwardly in the radial direction of the tubular member 27 and obliquely downward, and has a high-pressure abrasive supplied by an abrasive supplying device. Is incident on the polishing surface 5a at an appropriate inclination angle to remove the polishing agent or the like adhering to the polishing cloth in a clogged state, and the wafer 3 placed ahead of
The polishing agent can be sent between the polishing surface 5a and the polishing surface 5a.

The dressing pad 23 is rotatably attached to the tip of a dressing arm 29 fixed at an angle of about 90 ° with respect to the horizontally rotating swivel arm 4 (excluding means). It is a disk-shaped member and has a diameter dimension equivalent to the radius dimension of the polishing surface 5a. Thereby, the dressing pad 23,
The swivel arm 4 is swung horizontally by about 90 ° so that the polishing surface 5a
Excluded from above (state shown by chain line in Figure 1)
Then, it is arranged at a position on the polishing surface 5a which is inscribed on the outer periphery of the platen 5.

As shown in FIG. 5, the dressing pad 23 has a circular U-shaped cross section.
Along the outer edge thereof, there is provided a ring-shaped pressure contact surface 23a to be pressed against the polishing surface 5a. This pressure contact surface 2
For example, diamond abrasive grains 23b of about 100 mesh are electrodeposited on 3a in a uniformly distributed state.

In the example shown in FIG. 1, the dressing pad 23 is formed to have a diameter equal to the radius of the platen 5. 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. The size relationship between the dressing pad 23 and the platen 5 is not limited to the above-described dimensional relationship, and the dressing pad 23 is arranged so as to cover the entire polishing surface 5a of the platen 5 with which the wafer 3 is brought into contact. Can be contacted, and
It suffices that the dressing pad 23 can be swung by the balance of the frictional force generated between the dressing pad 23 and the platen 5.

The wafer polishing apparatus 20 having the above structure
To carry out the polishing operation of the wafer 3 using
The head 2 to which is attached is placed on the polishing surface 5 a of the platen 5 by horizontally turning the turning arm 4.
Then, while the platen 5 and the head 2 are horizontally swung, and while the polishing agent is ejected from the nozzle 22, a minute air pressure is supplied from a pressure air source to lower the wafer carrier 6 so that the surface of the wafer 2 to be polished is lowered. Polished surface 5
Pressure contact with a.

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 make such mutual movements, the wafer 3 is rubbed against the polishing surface 5a of the platen 5 via an abrasive, and the surface to be polished is polished. It will be.

Further, since the polishing agent is ejected toward the polishing surface 5a from the plurality of nozzles 22 arranged around the head 2, the polishing operation of the polishing surface 5a can be performed in parallel with the polishing operation of the wafer 3. The polishing agent or the like that has been clogged in the area sprayed with the polishing agent is removed. Therefore, since the polishing work and the dressing work are performed at the same time, the work efficiency can be improved, and since the dressing work is performed by the polishing agent, the surface to be polished of the wafer 3 is not damaged.

In this case, the wafer polishing apparatus 20 of this embodiment
In this case, since the polishing agents are supplied from multiple directions around the wafer 3 by the nozzles 22 provided in plural in the tubular member 28 arranged in the circumferential direction of the head 2, the wafer is always applied to the polishing surface 5a dressed with the polishing agent. 3 can be contacted. Further, by providing the plurality of nozzles 22 on the head 2 which is horizontally moved by the swivel arm 4, the abrasive agent ejected from the nozzles 22 is ejected over the polishing surface 5a over a wide range. Therefore, the dressing work can be performed uniformly.

The head 2 for supporting the wafer 3 is surely supported from the side by the roller 25 of the head supporting means 21 without hindering the horizontal turning motion, and
Since it is reliably supported from above by the shaft 36 and the weight 40, it is possible to prevent vibration of the head 2 due to jetting force of the abrasive from the nozzle 22 and mutual movement with the polishing surface 5a. Along with this, the supporting member 24 of the head supporting means 21 is replaced by the tubular member 27 of the nozzle 22.
Since it also supports the tubular member 27, the tubular member 27 can be reliably supported against the reaction force acting by the flow and ejection of the abrasive. As a result, the vibration acting on the wafer 3 can be prevented, and the flatness of the surface to be polished of the wafer 3 can be prevented from decreasing.

Further, for example, when exchanging the wafer 3 which has been polished, the exchanging operation is performed at a position where the swivel arm 4 is swung to remove the head 2 from the platen 5. In this state, the wafer polishing apparatus 20 performs the dressing operation by bringing the dressing pad 23 into pressure contact with the polishing surface 5a, so that it is possible to effectively use the dead time in which the wafer 3 is not polished.
It is possible to avoid mixing of foreign matters such as abrasive grains falling from the dressing pad 23 into the abrasive. Further, by using the dressing work with the dressing pad 23 together, it is possible to surely remove the clogging as compared with the case of using only the abrasive.

Although the dressing pad 23 is formed in a disk shape in this embodiment, the shape is not limited to this and may be any shape. Further, the dressing pad 23 may be rotated following the rotation of the polishing surface 5a, or may be rotated independently by attaching a drive motor or the like. Although the dressing arm 29 is fixed to the revolving arm 4, the dressing arm 29 may be connected / disconnected by a clutch instead.

Although the rolling element is composed of the roller 25, other rolling element such as a ball rotatably supported may be adopted. The number of rolling elements is not limited to three and may be any number.
Further, the number of nozzles 22, the inclination angle, the spraying pressure of the polishing agent, etc. may be set appropriately.

Further, although the tubular member 27 is formed in an arcuate shape arranged in the mutual gap of the rollers 25, instead of this, the roller 25 is avoided or a series of a series is formed so as to surround the outside of the rollers. It may be formed in a ring shape.

[0038]

As described in detail above, in the wafer polishing apparatus according to the present invention, a plurality of nozzles for spraying the polishing agent toward the polishing surface are arranged around the head in the circumferential direction. , The polishing surface around the head, which is moved relative to the polishing surface, is evenly dressed, and the wafer supported by the head is always brought into contact with the dressed polishing surface to improve the flatness of the surface to be polished. There is an effect that can be made. Moreover, since the nozzle is provided in the head that can be moved relative to the polishing surface, the polishing surface can be dressed over a wide range.

If head supporting means is provided around the head and the head is laterally supported by the rolling elements, the head will not vibrate due to the ejection force of the abrasive agent ejected from the nozzle. Can be supported not to. Further, since the tubular member to which the nozzle is attached is supported by the supporting member of the head supporting means, the vibration of the tubular member due to the flow / spraying of the polishing agent is also prevented, the vibration acting on the wafer is reduced, and the surface to be polished is flat. The effect is that the degree can be improved.

Further, if the dressing pad is brought into pressure contact with the polishing surface with the head removed from the polishing surface, dressing work on the polishing surface can be carried out even during useless time such as wafer replacement. In addition to the dressing with the abrasive, it is possible to perform more reliable and uniform dressing.

[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 vertical sectional view showing the wafer polishing apparatus of FIG.

3 is a vertical cross-sectional view showing a structure near a head of the wafer polishing apparatus of FIG.

4 is a plan view showing a nozzle of the wafer polishing apparatus of FIG.

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

FIG. 6 is a vertical sectional view showing a conventional example of a wafer polishing apparatus.

FIG. 7 is a vertical cross-sectional view illustrating a conventional example of dressing for a polishing cloth.

8 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 (exclusion means) 5 platen (polishing plate) 5a polishing surface 20 wafer polishing device 21 head support means 22 nozzle 23 dressing pad 24 support member 25 roller (rolling element) 27 tubular member

Claims (3)

[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 polishing the surface to be polished of the wafer. In a polishing apparatus for polishing a wafer by supplying a polishing agent between the head and a surface, a plurality of nozzles for ejecting the polishing agent toward the polishing surface are arranged around the head in the circumferential direction. Characteristic wafer polishing device. 2. A head supporting means for laterally supporting the outer peripheral surface of the head is provided around the head, wherein the head supporting means is provided in plural at intervals in the circumferential direction of the head. And a ring-shaped support member that rotatably supports the rolling members by connecting them to each other. A nozzle is attached along the support member and has an abrasive inside. 2. The wafer polishing apparatus according to claim 1, wherein the tubular member is provided at intervals in the longitudinal direction of the tubular member through which the gas flows. 3. An excluding means for excluding the head from the polishing surface, and a dressing pad which is brought into pressure contact with the polishing surface when the head is excluded, are provided. Wafer polishing equipment.