JPH10296627A - Polishing device and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably use an adsorptive member of a vacuum chucking device for long time and improve an yield in a semiconductor polishing process. SOLUTION: This device comprises a vacuum chuck 15 for adsorbing a workpiece (semiconductor wafer) 3 utilizing negative pressure through an adsorptive member 21, which is porous, has air permeability and is formed into a disk, provided. In this case, the thickness of the adsorptive member 21 can be made substantially thin than the thickness (10 mm-20 mm) of a conventional adsorptive member by setting its thickness to 2 mm-8 mm. This can prevent abrasives 4 containing abrasive grains and powder products from retaining in the adsorptive member 21 for a long time, as a result the adsorptive member 21 becomes hard to occur loading, which provides stable use for a long time.

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 a workpiece such as a semiconductor wafer (substrate).
In particular, the present invention relates to a polishing apparatus and a polishing method for adsorbing and polishing an object to be polished by a vacuum chuck.

[0002]

2. Description of the Related Art Such a conventional polishing apparatus is, for example, as shown in FIG. In FIG. 1, reference numeral 1 denotes a polishing platen, and a polishing pad 5 for performing a polishing action is attached to an upper surface of the polishing platen 1 so that they can be integrally rotated.

[0005] Reference numeral 15 denotes a vacuum chuck device, and the suction member 2 is provided at an opening of a casing 17 formed in an inverted bowl shape of the vacuum chuck device 15. The adsorbing member 2 is formed of a porous and air-permeable ceramic material, and is formed in a disk shape having a diameter that fits into the inner diameter of the opening of the casing 17.

A pressure plate 8 is integrally provided on the upper surface of the casing 17. A pipe-shaped pressure shaft 7 is rotatably connected to the center of the pressure plate 8 via a spherical bearing 6. I have. At one end of the pressure shaft 7, the shaft hole 7 a communicates with the space 17 a inside the suction member 2 of the casing 17, and at the other end, the shaft hole 7 a is connected to the negative pressure chamber ( Negative pressure source).

A semiconductor wafer (object to be polished) 3 is arranged outside the suction member 2 of the vacuum chuck device 15, and the semiconductor wafer 3 is
When the space 17a is made to have a negative pressure, the space 17a is adsorbed and held on the surface of the porous and air-permeable adsorbing member 2.
The semiconductor wafer 3 thus sucked and held is pressed against the polishing pad 5 by the pressure plate 8 and rotates relatively to the polishing pad 5.

At the center of the upper surface of the polishing pad 5 of the polishing table 1, an abrasive 4 containing abrasive grains is supplied from a polishing abrasive grain tank 26 by a drive pump 24, and the abrasive 4 containing abrasive grains is supplied to the semiconductor wafer 3 And is used to polish the semiconductor wafer 3 between the semiconductor wafer 3 and the polishing pad 5.

The operation of such a conventional polishing apparatus will be described with reference to the flowchart of FIG. First, when the semiconductor wafer 3 is unloaded from a wafer carrier (not shown; a container that accommodates the semiconductor wafer 3 and moves up and down) (step S1), the semiconductor wafer 3 is placed on the surface of the suction member 2 of the vacuum chuck device 15 under a negative pressure. (Step S2).

Then, the polishing platen 1 is connected to a vacuum chuck device 15.
The polishing operation of the semiconductor wafer 3 is performed by causing the abrasive 4 containing abrasive grains to enter and supply between the polishing pad 5 and the semiconductor wafer 3 while rotating the semiconductor wafer 3 relative to the suction member 2 (step S3).

When the polishing operation is completed, the suction of the semiconductor wafer 3 by the vacuum chuck device 15 is released (step S4), and then both surfaces of the semiconductor wafer 3 are cleaned using a cleaning agent, a Belclean brush or the like (step S4). Step S5). When the cleaning is completed, the semiconductor wafer 3 is loaded again into the wafer carrier (Step S).
6).

[0010]

However, in such a conventional polishing apparatus, the diameter of the suction member 2 is 2 mm.
The thickness is about 00 mm, and the thickness of the suction member 2 is about 10 to 20 mm in order to have necessary strength. As described above, the thickness of the suction member 2 has to be relatively thick in order to have the required strength, and thus has the following problems.

That is, as shown in FIGS. 11 and 12, during polishing or at the end of polishing, the negative pressure in the space 17a of the casing 17 is reduced due to the small gap between the peripheral edge of the semiconductor wafer 3 and the opening of the casing 17. The used abrasive-containing abrasive 4 penetrates into the adsorbing member 2 together with the powdery product 10 generated by the polishing, due to vacuum leakage in which the air is drawn into the adsorbing member 2 and the air enters the adsorbing member 2.

The abrasive 4 containing the abrasive grains and the powdery product 10 that have penetrated in this way remain on the way because the adsorption member 2 is thick, and increase with time. The abrasive 4 containing abrasive grains and the powdery product 10 penetrate deep into the porous portion of the peripheral portion of the adsorbing member 2 and fill the porous portion, solidify when dried, and prevent clogging. Wake up. For this reason, the suction member 2
In the peripheral portion, the degree of vacuum adsorption is deteriorated as compared with the central portion, and the semiconductor wafer 3 cannot obtain a polished surface having a uniform thickness between the central portion and the peripheral portion.

In addition, in the case of a commonly used abrasive 4 containing colloidal silica-based abrasive grains, the abrasive 4 penetrates into the adsorbing member 2, solidifies by drying, and cannot be removed by being fixed inside, and cannot be used. So the suction member 2
Cannot be used stably over a long period of time. Such a phenomenon tends to become more remarkable as the thickness of the suction member 2 increases.

When the abrasive 4 containing colloidal silica-based abrasive particles usually used for such polishing is dried on the surface of the adsorbing member 2 or the semiconductor wafer 3, the abrasive 4 is solidified to partially generate protrusions. I do. As shown in FIG. 13, when the semiconductor wafer 3 is adsorbed on the adsorbing member 2 and polished while keeping such protrusions 12 as it is, the semiconductor wafer 3 is uniformly adsorbed on the surface of the adsorbing member 2 made of a hard ceramic material. Without
Opposite side of protrusion 12 of semiconductor wafer 3 (polishing pad 5
Side) swells locally.

For this reason, at the beginning of polishing, the swollen portion of the semiconductor wafer 3 is polished before its surroundings, so that the thickness of the swollen portion of the semiconductor wafer 3 after polishing is larger than that of other portions. There is a problem in that the semiconductor wafer 3 becomes thinner, resulting in uneven thickness, resulting in a defective product, which deteriorates the yield in the polishing process of the semiconductor wafer 3.

Accordingly, the present invention provides a polishing apparatus and a polishing method capable of stably using a suction member of a vacuum chuck device for a long period of time and improving a yield in a polishing process of a semiconductor wafer. It is an issue.

[0017]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, a polishing apparatus according to the present invention is configured to apply a negative pressure to an object to be polished through a porous, air-permeable, disk-shaped suction member. In a polishing apparatus provided with a vacuum chuck to be sucked by,
The thickness of the suction member is set to about 2 mm to 8 mm, and the polishing method according to the present invention, when the object to be polished is suctioned to the suction member of the vacuum chuck by negative pressure and polished, The polishing method according to the present invention further comprises a step of performing a treatment for removing the adhering protrusions from the surface of the object to be polished that is adsorbed by the suction member. A process of removing the object to be polished by adsorbing the object to be polished and removing the object to be polished from the adsorbing member, and then removing the adhered protrusion from the surface of the adsorbing member on which the object to be polished is adsorbed It is characterized by having.

According to the polishing apparatus having the above-described structure, by setting the thickness of the suction member to about 2 mm to 8 mm, it is possible to significantly reduce the thickness of the conventional suction member. For this reason, it is possible to prevent the abrasive containing abrasive grains and the powdery product from staying in the adsorbing member for a long time, and the adsorbing member is unlikely to be clogged, and can be stably used for a long period of time. As a result, the processing accuracy of an object to be polished such as a semiconductor wafer can be improved.

According to the polishing method, when the object to be polished is attracted to the suction member of the vacuum chuck by negative pressure and polished, the surface of the object to be polished on the side to be adsorbed to the adsorption member before the adsorption is performed. By performing a process of removing adhered protrusions from the surface, it is possible to prevent the polished surface of the semiconductor wafer adsorbed by the adsorbing member from locally swelling, and to prevent unevenness in thickness due to polishing. In addition, the yield in the polishing process of a semiconductor wafer or the like can be improved.

Further, according to the above-mentioned polishing method, the object to be polished is attracted to the surface of the suction member of the vacuum chuck and polished, and after the object to be polished is removed from the suction member, the object to be polished by the suction member is removed. By performing a treatment to remove the adhering protrusions from the surface to be adsorbed, the polishing surface of the semiconductor wafer also adsorbed to the adsorbing member is prevented from locally expanding, and the thickness is reduced by polishing. The occurrence of unevenness can be prevented, and the yield in the polishing step of a semiconductor wafer or the like can be improved.

[0021]

Embodiments of the present invention will be specifically described below with reference to the drawings. 1 to 8
FIG. 1 is a diagram referred to for describing a polishing apparatus and a first embodiment of the present invention.

As shown in FIG. 1, the polishing apparatus according to the first embodiment of the present invention basically has the same configuration as the conventional one, but differs from the polishing apparatus in that the pressing shaft 7, a filter 20 is provided.
0 indicates that the abrasive 4 containing abrasive grains and the powdery product 10
1 is used to capture the space 17a of the casing 17 and the shaft hole 7a of the pressurizing shaft 7 so as not to go to the vacuum pump 22 even if it enters the space 17a.

At the opening of the casing 17 of the vacuum chuck device 15, similarly to the conventional suction member 2, a suction member formed of a porous and air-permeable ceramic material and formed in a disk shape is provided. 21 are provided. This adsorbing member 21 has a diameter of 200 mm as in the prior art.
The thickness is set at about 2 mm to 8 mm. As described above, since the thickness of the conventional suction member 2 is about 10 mm to 20 mm, in the present embodiment, the thickness of the suction member 21 is 1/5 to 1 This means that it is set to be as thin as 2/5.

When the semiconductor wafer 3 is attracted to the attracting member 21 of the vacuum chuck device 15 and polishing is performed,
Since the polishing is performed while the semiconductor wafer 3 is attracted by the negative pressure, the abrasive 4 containing the used abrasive grains and the powdery product 10 generated by the polishing are removed from the slight gap between the semiconductor wafer 3 and the attracting member 21. Is sucked by the negative pressure in the space 17 a of the casing 17 and penetrates into the suction member 21.

However, since the thickness of the adsorbing member 21 is reduced as described above, even if the abrasive 4 containing abrasive grains and the powdery product 10 penetrate from the peripheral portion of the adsorbing member 21, as shown in FIG. Since it is possible to penetrate and pass through the suction member 21 in the thickness direction, it is difficult for the suction member 21 to be clogged, and the suction member 21 can be stably used for a long period of time.

The abrasive 4 containing abrasive grains and the powdery product 10 which have entered the space 17 a of the casing 17 pass through the shaft hole 7 a of the pressure shaft 7 to the vacuum pump 22, and they are filtered by the filter 20. It can be prevented from being caught and entering the vacuum pump 22.

As described above, the abrasive member 4 and the powdery product 10 are unlikely to be clogged with the adsorbing member 21, but even if they are somewhat clogged, as shown in FIG.
2 allows easy removal and cleaning. That is, the pure water 28 is filled in the water tank 34 of the ultrasonic cleaner 32, and the ultrasonic vibrator 30 is placed on the bottom of the water tank 34.
The suction member 21 of the vacuum chuck device 15 is disposed above the pure water 28 by immersing the lower surface thereof.

In such a state, the ultrasonic cleaner 3
The ultrasonic vibrator 30 is ultrasonically vibrated, and pure water 2 is supplied from the shaft hole 7a of the pressure shaft 7 to the space 17a of the casing 17.
8, the pure water 28 flows from the space 17a toward the inside of the water tank 34 through the adsorbing member 21, and since the thickness of the adsorbing member 21 is small, the abrasive grains clogged in the adsorbing member 21 The abrasive 4 containing powder and the powdery product 10 are extruded from the inside of the adsorption member 21 into the pure water 28 of the water tank 34 and can be removed.

By the way, as shown in FIG.
The reinforcing member 11 is provided in the space 17a on the back side of the first member. As shown in FIG. 5, the reinforcing member 11 is formed in a plurality of concentrically arranged annular or arcuate shapes, and the annular space 13 between them is communicated by linear grooves 14 formed vertically and horizontally. Further, all the annular spaces 13 and the straight grooves 14 are in communication with the shaft hole 7 a of the pressure shaft 7. The annular space 13 and the straight groove 14 are
It can be said that it is also the space 17a of FIG.

For this reason, even if the thickness of the suction member 21 is smaller than the conventional one, it is ensured that the suction member 21 is deformed so as to be deflected in the thickness direction by the pressure applied during polishing and may be damaged in some cases. Can be prevented. Then, through the annular space 13 and the straight groove 14, a negative pressure can be applied uniformly over the entire surface of the suction member 21 or a water pressure can be applied uniformly.

Next, the operation of the polishing apparatus according to this embodiment will be described with reference to the flowchart of FIG. In the flowchart, step S1,
Steps S2 to S6 are the same as the operation of the conventional polishing apparatus, but in the present embodiment, Step S100 is inserted between Step S1 and Step S2, and Step S200 follows Step S6. Is different from the conventional operation in the point that is added.

That is, after the semiconductor wafer 3 is carried out of the wafer carrier (S1), the semiconductor wafer 3
Before the semiconductor wafer 3 is sucked by the vacuum chuck device 15 (S2), the suction member 21 of the vacuum chuck device 15
By cleaning the surface on the side adsorbed on the surface (S100), the abrasive 4 containing abrasive grains and the powdery product 10 locally formed on the surface of the semiconductor wafer 3 are dried and solidified. A process of removing the generated protrusion 12 is performed.

As a cleaning process for removing such protrusions 12, for example, as shown in FIG. 7, the semiconductor wafer 3 is moved in the direction of the arrow by rotating the Berglin brush 9, and the cleaning agent is used. This can be performed by rubbing the semiconductor wafer 3 with the brush tip (brush outer diameter).

By removing the protrusions 12 from the surface of the semiconductor wafer 3 in this manner, it is possible to prevent the thickness of the semiconductor wafer 3 from being uneven by polishing as in the prior art, and The yield in the polishing step can be improved.

On the other hand, after the semiconductor wafer 3 is loaded into the carrier (S6), the suction member 2 of the vacuum chuck device 15 is
3 is cleaned as shown in FIG. 3 and a process for removing the protrusions 12 formed on the outer surface of the suction member 21 is performed (S200).

In order to remove the protrusions 12 from the surface of the suction member 21, for example, as shown in FIG. 8, the vacuum chuck device 15 is moved from the carrier onto the grindstone set table 16, and the suction of the vacuum chuck device 15 is performed. Set the member 21 to the grindstone set table 16
The protrusions 12 formed on the surface of the suction member 21 can be removed by bringing the suction member 21 into contact with the whetstone 29 provided on the surface of the suction member 21 and rotating the whetstone 29 relative to the whetstone 29.

At this time, by rotating the pressure plate 8 and simultaneously eccentrically moving the pressure plate 8, the suction member 21 is rotated.
Can be uniformly polished by the grindstone 29. However, the pressure plate 8 may be stopped and only the grindstone set table 16 may be rotated and eccentrically moved. Alternatively, the pressure plate 8 and the grindstone set table 16 may be rotated. May be both rotated and eccentrically moved.

At the time of such processing, the pressing force applied to the grindstone 29 by the pressure plate 8 is set to a minimum necessary value so as not to be too large due to the hardness of the grindstone 29 and the protrusion 12. At the same time as this treatment, the washing is performed while washing water is flowing from the shaft hole 7a of the pressurizing shaft 7 newly connected to the water supply source.
Numeral 2 is pushed out of the casing 17 from the porous portion of the adsorbing member 21 to prevent the protrusions 12 from entering the porous portion of the adsorbing member 21 again to cause clogging.

Although the above embodiment has been described with reference to the case where the suction member 2 of the vacuum chuck device 15 is formed of a ceramic material, the material of the suction member 21 does not need to be limited to a ceramic material. Other materials, such as metal, can also be used.

In the above embodiment, the case where the reinforcing member 11 is formed in a ring or an arc is used.
Any structure may be used as long as negative pressure or water pressure can be applied to the entire surface of the adsorption member 21 such as arranging a large number of cylinders or prisms.

[0041]

As described above, according to the present invention,
By setting the thickness of the attraction member to about 2 mm to 8 mm, it is possible to make the thickness of the attraction member significantly smaller than that of the conventional attraction member. For this reason, it is possible to prevent the abrasive containing abrasive grains and the powdery product from staying in the adsorbing member for a long time, and the adsorbing member is unlikely to be clogged, and can be stably used for a long period of time. As a result, the processing accuracy of an object to be polished such as a semiconductor wafer can be improved.

Further, according to the polishing method of the present invention, when the object to be polished is attracted to the suction member of the vacuum chuck by negative pressure and polished, the side of the object to be polished that is adsorbed to the adsorption member before the suction is performed. By performing a process of removing the adhering protrusions from the surface of the semiconductor wafer, it is possible to prevent the polishing surface of the semiconductor wafer adsorbed by the suction member from locally expanding and prevent unevenness in thickness due to polishing. Thus, the yield in the polishing step of a semiconductor wafer or the like can be improved, and the processing accuracy of the semiconductor wafer or the like can be improved.

According to the polishing method of the present invention, the object to be polished is adsorbed on the surface of the suction member of the vacuum chuck and polished, and after the object to be polished is removed from the adsorption member, the object to be polished is removed. By performing a process of removing the adhering protrusions from the surface on which the object is adsorbed, the polished surface of the semiconductor wafer that is also adsorbed by the adsorption member is prevented from locally expanding, and the thickness is reduced by polishing. It is possible to prevent unevenness from occurring, and to improve the yield in the polishing step of a semiconductor wafer or the like, thereby improving the processing accuracy of the semiconductor wafer or the like.

Further, since the polishing operation is prevented from being stopped due to clogging of the suction member, the processing efficiency of the semiconductor wafer can be improved and the processing accuracy can be improved. In addition, by improving the processing accuracy of semiconductor wafers, SOI (Silicon On Insulato) has been improved.
r) When a LSI is manufactured like a substrate, characteristics are good, and high precision can be achieved in each manufacturing process of a semiconductor wafer which is advantageous for miniaturization. In addition, various planarizations in the manufacture of LSI can be stably performed by improving the processing accuracy.

Further, since the vacuum chuck device 15 using the porous adsorbing member 21 can be used, the polishing can be performed with higher precision than the polishing method using the back pad. , Vacuum chuck device 1
The advantage of the polishing method using No. 5 can be maximized.

Further, compared with the above-mentioned polishing method using the back pad, it is not necessary to replace the back pad one by one, so that maintenance can be simplified and consumables such as the back pad can be saved. In addition, the processing cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of a polishing apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a state during a polishing operation of the polishing apparatus shown in FIG.

FIG. 3 is a schematic diagram showing a state during a cleaning operation of the polishing apparatus shown in FIG. 1;

FIG. 4 is a side sectional view of the vacuum chuck device 15;

5 is a sectional view taken along line VV of the reinforcing member 11 of the vacuum chuck device 15 in FIG.

FIG. 6 is a flowchart showing an operation procedure of the polishing apparatus shown in FIG.

FIG. 7 is a side view showing a state in which the semiconductor wafer 3 is subjected to a cleaning process by the Velklin brush 9 before being suctioned by the suction member 21 of the vacuum chuck device 15.

FIG. 8 is a side cross-sectional view showing a state where the surface of the suction member 21 of the vacuum chuck device 15 is cleaned after the semiconductor wafer 3 is removed after polishing.

FIG. 9 is a schematic configuration diagram showing a conventional polishing apparatus.

FIG. 10 is a flowchart showing an operation procedure of a conventional polishing apparatus.

FIG. 11 is a schematic view showing a state during a polishing operation of a conventional polishing apparatus.

FIG. 12 is a schematic view showing a state in which the abrasive 4 containing abrasive grains and the powdery product 10 are clogged in the adsorption member 2;

FIG. 13 shows a state in which the semiconductor wafer 3 is attached to the suction member 2 without removing the protrusions 12 on the surface of the suction member 2 or the semiconductor wafer 3;
FIG. 3 is a schematic view showing a state where the liquid is adsorbed to the radiator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Polishing surface plate, 2, 21 ... Suction member, 3 ... Semiconductor wafer (substrate to be polished), 4 ... Abrasive containing abrasive grains, 5 ... Polishing pad, 6 ... Spherical bearing, 7 ... Pressing shaft, 7a ... Shaft Holes, 8: Pressure plate, 9: Berglin brush, 10: Powdery product, 11: Reinforcement member, 12: Projection, 13: Annular space, 14: Linear groove, 15: Vacuum chuck device, 16: Grinding stone Set stand, 17 ... casing, 17a ... space, 20 ...
Filter, 22: Vacuum pump (negative pressure source), 24: Drive pump, 26: Polishing abrasive tank, 28: Pure water, 29: Grinding stone, 30: Ultrasonic vibrator, 32: Ultrasonic cleaner, 34 ...
Aquarium

Claims (6)

[Claims] 1. A polishing apparatus provided with a vacuum chuck for adsorbing an object to be polished by a negative pressure through an adsorbing member formed in a disk shape and having air permeability, wherein the thickness of the adsorbing member is reduced. A polishing apparatus characterized by being set to about 2 mm to 8 mm. 2. The polishing apparatus according to claim 1, wherein a filter for preventing abrasive grains or the like from passing is provided between the suction member and a negative pressure source for generating the negative pressure. . 3. A reinforced structure is provided on a side of the suction member opposite to a side on which the object to be polished is suctioned.
A polishing apparatus according to claim 1. 4. The polishing apparatus according to claim 1, wherein the suction member is formed of a ceramic material. 5. When polishing an object to be polished to a suction member of a vacuum chuck by applying a negative pressure thereto and polishing the object, before the suction, an adhering protrusion is generated from a surface of the object to be polished from a surface of the object to be suctioned by the suction member. A polishing method comprising a step of performing a removing process. 6. A surface of the suction member on the side on which the object to be polished is adsorbed after the object to be polished is adsorbed and polished on the surface of the adsorption member of the vacuum chuck and the object to be polished is removed from the adsorption member. A polishing method, comprising a step of performing a treatment for removing adhered protrusions from the surface.