JP2002178260A - Polishing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve problems of abrasives fed from an abrasive feed part, used for the polishing of a material to be polished and including polishing chips generated by polishing, which causes a flaw in the surface to be polished and accelerates the deterioration of the flatness of a surface plate. SOLUTION: This polishing device 101 comprises the surface plate 2, a fixture 5 pushing a wafer retainer jig 4 having a semiconductor wafer 3, or the material to be polished, stuck thereto toward the polishing surface of the surface plate 2, an abrasive feed part 102 for feeding abrasive fluid 6 and a fluid jet part 103 washing away the abrasive fluid 6 including the polishing chips 11. The abrasive feed part 102 is disposed in the upstream of the wafer retainer jig 4 relative to the rotating direction of the surface plate 2 and in the radius direction of the surface plate 2. The fluid jet part 103 ejecting fluid for washing away the abrasive fluid 6 including the polishing chips 11 generated by the polishing is disposed in the downstream of the wafer retainer jig 4 and in the radius direction of the surface plate 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polishing apparatus for polishing an object to be polished while pressing an object to be polished such as a semiconductor wafer against a surface plate and supplying an abrasive.

[0002]

2. Description of the Related Art As an example of a conventional polishing apparatus, a single-wafer polishing apparatus for polishing a back surface of a semiconductor wafer is shown in FIGS. 6 and FIG. 7 which is a cross-sectional view showing the state of the abrasive before and after passing through the semiconductor wafer. As shown in FIG. 4, the polishing apparatus 1 includes a surface plate 2, a fixture 5 for pressing a wafer holding jig 4 on which a semiconductor wafer 3 to be polished is stuck on a polished surface of the surface plate 2, and a polishing agent. And an abrasive supply section 7 for supplying a polishing abrasive liquid 6 containing abrasive grains. Surface plate 2 is a motor (not shown)
And is rotatable about an axis (indicated by an arrow in the figure). As shown in FIG. 6, for example, three semiconductor wafers 3 are placed at arbitrary positions on the wafer holding jig 4.
With the polished surface 3a facing upward, the bonding wax 8, the medicine packaging paper 9, the wax 8, and the semiconductor wafer 3 are stacked and bonded in this order. The packaging paper 9 holds the semiconductor wafer 3 on the wafer holding jig 4.
This is to protect it from being scratched when it is attached to and detached from. The fixture 5 is connected to a motor (not shown) and an elevating cylinder (not shown) so as to be able to move up and down and rotate around the axis (indicated by an arrow in the figure). Can be rotated while being pressed against the surface plate 2 with an arbitrary pressure. That is, the movement of the base 2 and the wafer holding jig 4 is such that the wafer holding jig 4 rotates at an eccentric position on the base 2 that rotates. On the other hand, an abrasive supply unit 7 for supplying the polishing slurry 6 onto the surface plate 2 is disposed in the sky near the center of the surface plate 2, for example, on the surface plate 2 which rotates from a nozzle-like polishing solution outflow hole 10. The polishing liquid 6 is dropped. The abrasive supply section 7 is connected to an abrasive tank (not shown) in which the abrasive is stored. The polishing liquid 6 dropped on the surface plate 2 spreads on the surface plate 2 due to the centrifugal force of the rotating surface plate 2. Polishing abrasive fluid outlet 1
The position of the polishing liquid 6 is adjusted by, for example, changing the disposition position and the supply pressure of the semiconductor wafer 3 with respect to the semiconductor wafer 3.
The polishing liquid 6 is made to spread all over. In addition, surface plate 2
In order to supply the polishing liquid 6 more uniformly, the polishing liquid outflow holes 10 may be provided in plural and arranged in the radial direction of the platen 2. Thus, polishing is performed in a state where the polishing liquid 6 is interposed between the surface 3a to be polished of the semiconductor wafer 3 and the surface plate 2. As shown in FIG. 7, when the supplied new polishing liquid 6 passes through the semiconductor wafer 3, the polishing liquid 6 contains polishing dust 11 generated by polishing. Some of the polishing liquid 6 containing the polishing dust 11 is centrifugally applied to the platen 2.
It flows out of the tank and is collected by the waste liquid receiving part 12, but the surface plate 2
The polishing liquid 6 remaining on the wafer rotates and is mixed again with the new polishing liquid 6 supplied from the polishing liquid outflow hole 10 to be used for polishing the semiconductor wafer 3.

When the above-mentioned polishing operation is continued for a predetermined time, abrasive grains and polishing dust 11 adhere to the surface plate 2 and the flatness of the surface plate 2 is deteriorated, so that the polishing performance is deteriorated. It is necessary to carry out a correction operation for restoring the flatness of the surface plate 2 by using the same. This correction operation may be performed separately from the polishing of the semiconductor wafer 3 or may be performed in parallel with the polishing operation of the semiconductor wafer 3. That is, in the former, the correction ring is located at a position deviated from the surface plate 2 during the polishing operation of the semiconductor wafer 3 and is set on the surface plate 2 only during the correction operation. On the other hand, in the latter, as shown in FIG. 5, the correction ring 13 is always installed on the surface plate 2 even when polishing the semiconductor wafer 3. The correction ring 13 is provided with a diamond electrodeposition ring surface 14 on the surface on which the surface plate 2 is polished. The correction method is as follows. The diamond electrodeposition ring surface 14 of the correction ring 13 is brought into contact with the polished surface of the rotating platen 2 and the correction ring 13 is rotated around the axis, whereby the polished surface of the platen 2 is thinned to recover flatness. It is to let. The driving force of the correction ring 13 is, for example, the correction ring 1 in FIG.
3 is simply placed on the surface plate 2 by its own weight, two rotatable guide rings 15 supported by an arm from the outside are arranged, and the correction ring 13 is rotatably held. The board 2 is rotated by a rotational force generated by a difference in peripheral speed between a radial inside and a radial outside, but may be forcibly rotated by being connected to a motor (not shown) or the like. The diameter of the correction ring 13 is larger than the diameter of the wafer holding jig 4, and is arranged so as to correct all the regions where the semiconductor wafer 3 passes on the surface plate 2. When a repair operation is performed in parallel with the polishing operation of the semiconductor wafer 3, since the repair ring 13 is constantly pressed onto the surface plate 2, the polishing grind 6 contains the polishing waste 11 by polishing the semiconductor wafer 3. In addition, polishing dust 11 generated by polishing the surface plate 2 by the correction ring 13 is also included.

In the above description, a single set of the wafer holding jig 4, the polishing agent supply unit 7, and the correction ring 13 on the platen 2 has been described. However, in order to increase the throughput of the polishing operation, the platen is increased. There is also a case where a plurality of sets are installed on the second.

[0005]

The conventional method has the following problems. The abrasive supplied from the abrasive supply unit is
It is used for polishing an object to be polished, and at this time, polishing dust generated by polishing is included in the abrasive. Some of the abrasive containing the polishing debris flows out of the surface plate due to centrifugal force, but the abrasive remaining on the surface plate rotates and again, with new abrasive supplied from the abrasive supply unit. It will be used for polishing the object to be polished.
As this is repeated, the amount of polishing debris contained in the abrasive increases, causing damage to the surface to be polished of the object to be polished, and also promoting deterioration of the flatness of the surface plate. When the flatness of the surface plate is deteriorated, a repair operation using a repair ring is required, and when the repair operation is performed as a separate operation from the polishing operation, there is a problem that the throughput during the repair is naturally reduced. Further, as another working method, when the repair work is performed in parallel with the polishing work of the object to be polished, the polishing debris from the surface plate generated by the repair work is also included in the polishing agent. The danger of scratching has increased. In addition, arranging the correction ring on the surface plate even during the polishing operation reduces the space for arranging the object to be polished on the surface plate, which hinders an increase in throughput.

SUMMARY OF THE INVENTION It is an object of the present invention to prevent an abrasive containing polishing waste once used for polishing an object to be polished from being used again for polishing the object to be polished, and to polish the object to be polished with the polishing debris. In addition to preventing the surface from being scratched, the flatness life of the surface plate is extended, the frequency of the repair work is reduced, and the throughput is increased.

[0007]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems, and has a surface plate rotating about a first rotation axis and a second plate eccentrically arranged from the first rotation axis. A workpiece holder that rotates about the rotation axis of the workpiece and holds a thin plate-like workpiece on the lower surface, such that the surface to be polished of the workpiece is in close proximity to the surface plate, and is placed on the surface plate. In a polishing apparatus for polishing a surface to be polished by rotating a surface plate and an object-to-be-polished while supplying an abrasive, an abrasive-supplying portion is provided upstream of the object-to-be-polished holding portion with respect to a rotation direction of the surface plate. And a fluid ejecting unit which is arranged in the radial direction of the surface plate and injects a fluid for flushing an abrasive containing polishing debris generated from polishing from the surface plate on the downstream side of the workpiece holding unit and in the radial direction of the surface plate. A polishing apparatus characterized in that the polishing apparatus is disposed in a polishing apparatus.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In a polishing apparatus according to the present invention, a polishing agent supply section is arranged upstream of a workpiece holding section with respect to a rotation direction of a surface plate and in a radial direction of the surface plate, and polishing dust generated by polishing is provided. A fluid ejecting unit for ejecting a fluid for flushing the abrasive containing from the surface plate is disposed downstream of the workpiece holding unit and in the radial direction of the surface plate. Any fluid may be used as the fluid to be ejected from the fluid ejecting unit as long as it is harmless to the object to be polished by washing away the abrasive containing the polishing debris generated by polishing.
For example, liquids such as water, organic solvents, acids, alkalis, and surfactants may be used, and gases such as air and nitrogen may be used.
Desirable is an easy waste liquid treatment. In this respect, a gas is good, but a liquid is good in terms of the power to wash away the abrasive. Further, a gas and liquid fluid ejecting unit may be provided together. The fluid ejecting unit that ejects the fluid has a plurality of ejection holes to more reliably wash out abrasives containing abrasive debris and is arranged in the radial direction of the platen, and the ejection amount is variable for each of the ejection holes It is preferable to provide an injection pressure adjusting cock for changing the size of the injection hole or adjusting the injection pressure in order to achieve this. In addition, it is preferable to arrange the injection holes on the outer periphery of the injection holes near the center of the surface plate so as to be obliquely located downstream along the rotation direction of the surface plate so that the flushing with the fluid can be suitably performed following the rotating surface plate.

When the polishing operation for polishing the object to be polished and the correction operation for correcting the flatness of the surface plate using the correction ring are performed in parallel, in addition to the above, the correction ring is The polishing agent is disposed downstream of the workpiece holding section with respect to the rotation direction, but the abrasive supply section is disposed upstream of the workpiece holding section and in the radial direction of the platen, and polishing including polishing debris generated by polishing is performed. A fluid ejecting unit for ejecting a fluid for flushing the agent from the surface plate is disposed downstream of the correction ring and in a radial direction of the surface plate.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As an example of a polishing apparatus according to the present invention, a single-wafer type polishing apparatus 101 for polishing a back surface of a semiconductor wafer will be described with reference to perspective views 1 and 2 showing the structure of a main part. FIGS. 1 and 2 show a configuration in which the correction work of the surface plate by the correction ring and the polishing operation are performed separately, and FIG. 3 shows a case in which the correction work of the surface plate and the polishing operation by the correction ring are performed in parallel. Configuration. 4 to 7 are denoted by the same reference numerals and description thereof is omitted. A polishing apparatus 101 shown in FIG. 1 includes a fixture 5 that presses a surface plate 2 and a wafer holding jig 4 to which a semiconductor wafer 3 as an object to be polished is stuck against a polished surface of the surface plate 2.
A polishing agent supply unit 102 for supplying the polishing slurry 6, and a fluid ejecting unit 103 for washing away the polishing slurry 6 containing the polishing debris 11. The polishing agent supply unit 102 is rotated with respect to the rotation direction of the platen 2. A fluid ejecting unit 103 arranged upstream of the wafer holding jig 4 and in the radial direction of the surface plate 2 for injecting a fluid for flushing the polishing liquid 6 containing polishing dust 11 generated by polishing from the surface plate 2 is provided. It is arranged on the downstream side of the wafer holding jig 4 and in the radial direction of the platen 2. The polishing agent supply section 102 is on a cylinder having a plurality of polishing slurry outflow holes 104, and the polishing slurry 6 flows down onto the surface plate 2 from the plurality of polishing slurry outflow holes 104.
As a result, a uniform polishing liquid 6 can be supplied to the semiconductor wafer 3. The fluid ejection unit 103 includes a plurality of fluid ejection holes 105.
The water 106 is vigorously jetted onto the surface plate 2 from the plurality of fluid jet holes 105. Fluid ejection unit 10
3 has an injection pressure adjusting cock 107 so that the injection pressure can be adjusted. The fluid injection holes 105 are opened slightly below and toward the outer periphery of the surface plate 2 so that the polishing liquid 6 containing the polishing debris 11 flows out of the surface plate 2. The polishing liquid 6 containing the flushed polishing dust 11 is collected by the waste liquid receiving unit 12. That is, the polishing liquid 6 including the polishing debris 11 that has passed through the semiconductor wafer 3 is entirely washed away and is not used again for polishing the semiconductor wafer 3, and the semiconductor wafer 3 is always polished with the new polishing liquid 6. As a result, suitable polishing can be performed without damaging the polished surface 3a. It is expected that the usage amount of the polishing liquid 6 will increase slightly, but this can be easily solved by purifying the collected waste liquid and reusing it.

Here, for the sake of explanation, the wafer holding jig 4
Has been described, but even when the number of the wafer holding jigs 4 is plural, the same number of the abrasive supply units 1 are required.
02 and the fluid ejection unit 103 may be arranged as described above. FIG. 2 shows an example in which two wafer holding jigs 4 are provided.

Next, FIG. 3 shows a case where the work of polishing the semiconductor wafer 3 and the work of correcting the flatness of the surface plate 2 by the correction ring 13 are performed in parallel. This is the same as above except that the correction ring 13 is arranged downstream of the wafer holding jig 4 with respect to the rotation direction of the surface plate 2. Further, even when a plurality of sets of the wafer holding jig 4 and the corresponding correction ring 13 are arranged, the polishing agent supply unit 102 is connected to each wafer holding jig 4.
Of the fluid injection unit 103 and the correction ring 13
It may be located downstream of.

[0013]

According to the polishing apparatus of the present invention, the polishing agent once used for polishing the object to be polished and the abrasive containing the polishing debris are not used again for polishing the object to be polished. The surface to be polished can be prevented from being scratched, the life of the flatness of the platen can be extended, the frequency of repair work can be reduced, and the throughput can be increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of a polishing apparatus according to the present invention (one polished object).

FIG. 2 is a perspective view of a main part of a polishing apparatus according to the present invention (two polished objects).

FIG. 3 is a perspective view of a main part of a polishing apparatus according to the present invention (with a correction ring).

FIG. 4 is a perspective view of a main part of a conventional polishing apparatus.

FIG. 5 is a perspective view of a main part of a conventional polishing apparatus (with a correction ring).

FIG. 6 is an explanatory view illustrating a polishing object holding jig.

FIG. 7 is an explanatory view showing a state of a polishing abrasive liquid before and after passing through a semiconductor wafer.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Polishing device 102 Abrasive supply part 103 Fluid ejecting part 104 Polishing abrasive liquid outlet 105 Fluid ejecting hole 106 Water 107 Injection pressure adjusting cock

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01L 21/304 622 H01L 21/304 622Q

Claims (7)

[Claims] A platen rotating about a first rotation axis;
A polishing object holding portion that rotates about a second rotation axis eccentrically arranged from the rotation axis and holds a thin plate-like polishing object on the lower surface, and the polishing surface of the polishing object is close to the surface plate. In a polishing apparatus that rotates the surface plate and the object-to-be-polished while holding the surface of the object to be polished while supplying the abrasive onto the surface plate and polishing the surface to be polished, the polishing agent supply portion is moved in the rotation direction of the surface plate. On the other hand, a fluid ejecting unit, which is disposed on the upstream side of the polishing object holding unit and in the radial direction of the surface plate and injects a fluid for flushing an abrasive containing polishing debris generated by polishing from the surface plate, is provided. A polishing apparatus, wherein the polishing apparatus is arranged on the downstream side of the table and in the radial direction of the platen. A surface plate rotating about a first rotation axis;
A polishing object holding portion that rotates about a second rotation axis eccentrically arranged from the rotation axis and holds a thin plate-like polishing object on the lower surface, and the polishing surface of the polishing object is close to the surface plate. A polishing operation of rotating the surface plate and the object-to-be-polished holding portion while supplying the abrasive onto the surface plate and polishing the surface to be polished, and a third operation for correcting a change with time of the surface plate. A correction ring that rotates around the rotation axis of the platen is arranged downstream of the workpiece holder with respect to the rotation direction of the platen, and the correction work of polishing the platen by rotating the platen and the correction ring is performed in parallel. In a polishing apparatus, an abrasive supply unit is disposed upstream of a workpiece holding unit with respect to a rotation direction of a surface plate and in a radial direction of the surface plate, and an abrasive containing polishing debris generated by polishing is washed off from the surface plate. The fluid ejecting part that ejects the fluid to the downstream of the correction ring and in the radial direction of the platen. Polishing apparatus characterized by the location. 3. A plurality of workpiece holders are arranged on a surface plate.
2. The polishing apparatus according to claim 1, wherein an abrasive supply unit and a fluid ejection unit are arranged for each of the workpiece holding units. 4. A polishing machine according to claim 1, wherein a plurality of sets of the object-to-be-polished holding parts and the corresponding correction rings are arranged on the surface plate, and an abrasive supply part and a fluid ejecting part are arranged for each set. 3. The polishing apparatus according to item 2. 5. The polishing apparatus according to claim 1, wherein the object to be polished is a semiconductor wafer. 6. The polishing apparatus according to claim 1, wherein the fluid is a liquid. 7. The polishing apparatus according to claim 1, wherein the fluid is a gas.