JP4079151B2 - Polishing method - Google Patents

Description

The present invention relates to a polishing method for polishing an object to be polished such as a semiconductor wafer, and in particular, by providing a grindable dressing tool around a wafer in a wafer holding portion, the occupation area of the dresser is reduced and stable polishing performance is obtained. It is intended to be.

  Conventionally, as a means for polishing a wafer for the purpose of flattening an interlayer insulating film formed on the surface of a semiconductor wafer, polishing is performed by pressing the wafer against a polishing cloth fixed on a rotating surface plate. The device is known.

  In this type of polishing apparatus, as the number of processed wafers increases, the polishing cloth becomes clogged by abrasives and polishing debris. In addition, the polishing cloth is deformed or worn by the rotation of the wafer and the load from the wafer side. As a result, degradation of polishing performance such as a decrease in polishing rate, wafer damage or contamination, and the like occur.

  In order to cope with such a situation, it is known to add a dressing function for reclaiming a clogged polishing cloth to a polishing apparatus (for example, see Patent Documents 1 and 2).

  10 to 17 show an example of a conventional polishing process using a polishing apparatus having a dressing function. The main body 10 of the polishing apparatus is provided with a surface plate 12 having a polishing cloth fixed to the surface of the plate and a wafer receiver 14 in the vicinity of the surface plate 12. In addition, as shown in FIG. 17, the body 10 is provided with a dresser 24 held by a dresser holding portion 22 so as to be movable. However, in FIG. As the dressing tool of the dresser 24, one of a wire brush, a resin brush, a diamond electrodeposition plate and the like is used.

  As shown in FIG. 18, the wafer holding unit 18 is movable while holding the wafer 16 inside the guide 26 by vacuum suction or the like. The wafer 16 is in a state where the wafer 16 is in pressure contact with the polishing cloth on the surface plate 12. It is configured to be rotationally driven through 28.

  In the process of FIG. 10, the wafer 16 to be processed is placed on the wafer receiver 14. In the process of FIG. 11, the wafer 16 is sucked and held by the wafer holding unit 18.

  Next, in the process of FIG. 12, the wafer holding part 18 is moved to the center part of the surface plate 12 in the wafer holding state. In the process of FIG. 13, the wafer holding unit 18 is lowered and pressed against the polishing cloth on the surface plate 12 that rotates the wafer 16. Polishing is performed by rotating the wafer 16 in a holding / pressing state while supplying an abrasive from the dropping nozzle 20 onto the surface plate 12.

  When the polishing is completed, the wafer 16 is lifted from the surface plate 12 by the wafer holder 18 in the step of FIG. In the process of FIG. 15, the wafer holding unit 18 is moved to the wafer receiver 14 while the wafer is being held, and the wafer 16 is removed from the wafer holding unit 18 on the wafer receiver 14 by releasing suction and applying water pressure.

  Next, in the process of FIG. 16, the wafer holding unit 18 is returned to the initial position. In the step of FIG. 17, after the dresser 24 is moved onto the surface plate 12 by the dresser holding unit 22, dressing is performed while pressing the dressing tool of the dresser 24 against the polishing cloth on the surface plate 12 that rotates. Do. In this case, the polishing pad can be cleaned by supplying a cleaning liquid such as pure water from a pipe (not shown).

When the dressing is completed, the process returns to the step shown in FIG. 10 and the next wafer is polished in the same manner as described above. Note that dressing is not performed every time polishing of one wafer is completed, but may be performed every time polishing of a plurality of wafers is completed.
JP-A-4-364730 JP 7-254578 A

  According to the conventional dressing means described above, since the dresser 24 is provided independently of the wafer holder 18 and is driven to rotate independently, the occupation area of the dresser 24 on the surface plate 12 is large. It is difficult to provide a plurality of wafer holders 18 and a mechanism for holding, rotating, moving, etc. for the dresser 24 is necessary, and the configuration is complicated.

  Further, since the above conventional dressing means performs the dressing process separately from the polishing process, there are disadvantages that the polishing performance is not stable and the throughput is lowered.

  In general, the following performances (a) to (d) are required for dressing.

(B) Scraping or polishing clogged parts on polishing cloth (grindability)
(B) Removal of foreign matter on the polishing cloth (surface cleanability)
(C) Permanent deformation (pushability) with an elastic polishing cloth
(D) Fuzz alignment (track alignment) with fibrous polishing cloth, etc.
Conventionally, various dressing tools have been proposed. However, at present, there is no one dressing tool that satisfies all the performance requirements (a) to (d). Therefore, the conventional dressing means described above has a disadvantage that any performance is unsatisfactory.

  For example, in a case where a diamond electrodeposition plate having high grindability is used as a dressing tool, polishing cloth cutting scraps and falling diamond grains remain on the polishing cloth, which adversely affects the wafer such as damage and contamination. Further, in the case of using a dressing tool having no cleaning property, the abrasive contaminated with the dresser is supplied to the object to be polished.

An object of the present invention is to provide a novel polishing method capable of reducing the area occupied by a dresser and obtaining stable polishing performance.

In the polishing method according to the present invention, a polishing cloth is fixed to a surface of a surface plate that can be driven to rotate, and while the object to be polished is held by a holding part, the object to be polished held by the holding part is rotated and the surface is fixed. A polishing method for polishing by pressing against the polishing cloth during rotation of a disc, wherein a grinding dressing tool that is independently driven to rotate around a portion for holding an object to be polished in the holding portion is provided, and further the dressing Another dressing tool of a different type from the tool is provided, and the polishing cloth is dressed by independently rotating and driving these different kinds of dressing tools in parallel with the polishing of the object to be polished. Is.

According to the configuration of the present invention, since the grindable dressing tool is provided around the portion for holding the wafer in the holding portion for holding the wafer as an object to be polished, the dresser is provided independently of the wafer holding portion. Therefore, the area occupied by the dresser on the surface plate can be reduced, and the holding, rotating and moving mechanisms for the dressing tool can be shared with the wafer holder. Therefore, the configuration can be simplified, and it becomes easy to provide a plurality of wafer holders on the surface plate.
In addition, since the abrasive cloth is subjected to grindable dressing in parallel with the polishing of the wafer, stable polishing performance can be obtained and throughput can be improved.

Moreover, in the said grinding | polishing method, it is good also as dressing the said polishing cloth by rotationally driving the said holding | maintenance part and the said dressing tool independently .
Furthermore, in the polishing method, the holding portion may be swung while being rotated.
In the polishing method, a rotating shaft connected to the grindable dressing tool may be moved up and down, and the grindable dressing tool may be lowered at an appropriate time to add grindable dressing.

  According to the present invention, since the grindable dressing tool is provided around the wafer in the wafer holding portion and the grindable dressing is performed in parallel with the polishing, (a) reduction of the dresser occupation area, (b) Effects such as simplification of dressing mechanism, (c) stabilization of polishing performance, and (d) improvement of throughput can be obtained.

  Further, if the wafer holding portion is rotated while being rotated, the effect of improving the polishing efficiency as well as the uniformity of the dressing can be obtained.

  Furthermore, if the wafer holder and the grindable dressing tool are rotationally driven independently of each other, or if the wafer holder and the grindable dressing tool and other types of dressing tools are rotationally driven independently of each other, fine dressing is possible. The effect that control becomes possible is also acquired.

  Furthermore, if a plurality of wafer holders are provided for one surface plate, and a grindable dressing tool is provided for each wafer holder so that grindability dressing is performed in parallel with polishing, the throughput is greatly increased. An effect that can be improved is also obtained.

  FIG. 1 shows a polishing apparatus according to an embodiment of the present invention. FIG. 2 shows a state of wafer polishing by the apparatus of FIG.

  As shown in FIG. 2, the main body 10 is provided with a surface plate 12 having a polishing cloth 12a fixed to the surface of the plate. The surface plate 12 is rotationally driven by a motor or the like (not shown). In the main body 10, a wafer receiver 14 for placing a wafer as an object to be polished is provided in the vicinity of the surface plate 12.

  The tool / wafer holding section 30 is movable while holding the wafer 16 inside the guide 34 by vacuum suction or the like, as described above with reference to FIGS. 10 to 18, and as shown in FIG. In a state of being in pressure contact with 12, it is driven to rotate through a rotating shaft 38.

  In the tool / wafer holding unit 30, a grinding tool 36 is provided in a ring shape around a portion for holding the wafer 16 (inside the guide 34). As the grinding tool 36, a diamond electrodeposition plate or the like can be used. Instead of the grinding tool 36, other dressing tools such as a brush and a ceramic plate may be provided depending on the purpose.

  In the tool / wafer holding unit 30, a ring-shaped groove S that opens on the upper surface of the holding unit 30 is provided in a portion between the guide 34 and the grinding tool 36, and the groove 30 is communicated with the groove S. A large number of holes R penetrating to the bottom surface are provided in a ring shape. The polishing agent P supplied from the dropping nozzle 40 is supplied to the wafer 16 through the groove S and the hole R without being hindered by a dressing tool such as the grinding tool 36, so that stable polishing can be performed.

  The main body 10 is provided with a discharge portion 32 so as to surround the surface plate 12 and extend downward. The grinding scraps are moved outward by centrifugal force, fall from the surface plate 12 to the discharge unit 32, and are removed. In addition, the used abrasive is also discharged through the discharge unit 32.

  In the polishing process, the wafer 16 is transferred from the wafer receiver 14 onto the surface plate 12 by the tool / wafer holder 30 in the same manner as described with reference to FIGS. While rotating 16, the wafer 16 is pressed against the polishing cloth 12a on the surface plate 12 to perform polishing. During the polishing, the polishing agent P is supplied from the dropping nozzle 40 to the wafer 16 and the polishing pad 12a through the groove S and the hole R as shown in FIG. In addition, during polishing, the grinding tool 36 is pressed against the polishing pad 12a while rotating, so that the polishing pad 12a is subjected to a grinding dressing process.

  When the polishing is completed, the wafer 16 is returned to the wafer receiver 14 and the wafer 16 is removed from the tool / wafer holding portion 30 and the holding portion 30 is returned to the initial position in the same manner as described with reference to FIGS.

  According to the polishing apparatus described above, the area occupied by the dresser on the surface plate 12 is reduced as compared with the conventional apparatus shown in FIG. Further, since the mechanism for holding, rotating, and moving the dresser is shared with the wafer holding unit, the configuration is simple. Further, since dressing of the polishing cloth is performed simultaneously with the wafer polishing, a stable polishing performance can be obtained, and an independent dressing process as shown in FIG. 17 is not required, thereby improving the throughput.

  FIG. 3 shows a modified example of the tool / wafer holding portion, and the same parts as those in FIG.

  A feature of the tool / wafer holding unit 30 in FIG. 3 is that a brush 37 is provided in a ring shape in a portion between the grinding tool 36 and the hole R on the bottom surface of the holding unit 30. This configuration is intended to grind the clogged portion of the polishing pad 12 a with the outer grinding tool 36 and to scrape the grinding scraps outward with the inner brush 37 so as not to go to the wafer 16.

  Since the groove S and the hole R are provided inside the brush 37, the abrasive P can be supplied to the wafer 16 from the dropping nozzle 40 through the groove S and the hole R without being obstructed by the grinding tool 36 and the brush 37. .

  In the example of FIG. 3, as a different type of dressing tool, a grindable tool (grinding tool 36) and a surface-cleaning tool (brush 37) are combined, but a grindable tool and a pushable tool (for example, an alumina ceramic plate). ), A combination of an indentable type and a surface-cleaning type, etc., and may be selected according to the purpose.

  FIG. 4 shows a tool / wafer holding unit according to another embodiment of the present invention. The same parts as those in FIG.

  A feature of the tool / wafer holding unit 30 in FIG. 4 is that the tool holding unit 30b provided with the polishing tool 36 is configured to be driven to rotate independently of the wafer holding unit 30a holding the wafer 16. . That is, the grinding tool 36 is fixed to the bottom surface of the tool holding unit 30b provided so as to cover the wafer holding unit 30a, and the holding unit 30b is coaxial with the outer side of the rotating shaft 38a that rotationally drives the holding unit 30a. It is rotationally driven via the rotating shaft 38b arrange | positioned. The holding portion 30b is provided with a groove Sb in a ring shape corresponding to the groove S provided in the holding portion 30a, and the polishing agent P is applied to the wafer 16 from the dropping nozzle 40 through the grooves Sb, S and the hole R. Can be supplied.

  According to the configuration of FIG. 4, dressing can be performed on the grinding tool 36 at an optimum rotational speed. The example of FIG. 4 is configured such that the dressing tool is rotationally driven independently of the wafer holding unit in the configuration of FIG. 2, but in the configuration of FIG. 3, different types of dressing are performed in the same manner as shown in FIG. The tool (36, 37) can be configured to be driven to rotate independently of the wafer holder.

  FIG. 5 shows a modified example of the tool / wafer holding section, and the same parts as those in FIGS.

  A feature of the tool / wafer holding unit 30 of FIG. 5 is that different kinds of dressing tools are driven to rotate independently of each other. That is, the brush 37 is provided in a ring shape outside the hole R in the wafer holding portion 30a, and is rotationally driven together with the holding portion 30a by the rotating shaft 38a. The grinding tool 36 is rotated in the same manner as described in FIG. Thus, it is rotationally driven together with the tool holding portion 30b.

  According to the configuration of FIG. 5, dressing can be performed on the grinding tool 36 at an optimum rotational speed. In the configuration of FIG. 5, the brush 37 may be driven to rotate independently of the grinding tool 36 and the wafer holding unit 30a. In this way, the brush 37 can be dressed at an optimum rotational speed.

  FIG. 6 shows a polishing apparatus according to still another embodiment of the present invention. The same parts as those in FIG.

  The apparatus shown in FIG. 6 is characterized in that the tool / wafer holding unit 30 is swung while being rotated. As an example, a support / guide member 33 for supporting and guiding the movable portion 31 is provided on the upper portion of the main body 10, and a tool / wafer holding portion 30 is attached to the movable portion 31, and the movable portion is driven by driving means such as a cylinder (not shown). 31 is driven reciprocally in the directions of arrows A and A ′. As the tool / wafer holding unit 30, any of the types described above with reference to FIGS.

  According to the configuration of FIG. 6, the uniformity of dressing within the surface of the surface plate 12 can be further improved as compared with that of FIG. Also, the polishing efficiency is improved as compared with that of FIG.

  FIG. 7 shows a modification of the polishing / dressing part. The feature of the example of FIG. 7 is that three tool / wafer holders 30A to 30C are arranged on the surface plate 12 that is rotationally driven in the direction of arrow K, and these holders 30A to 30C are rotated respectively. That is, it is configured to rotate in the direction of the arrow through the shafts 38A to 38C. As the holding portions 30A to 30C, any of the types described above with reference to FIGS.

  According to the configuration of FIG. 7, the throughput is improved about three times as compared with that of FIG. The number of tool / wafer holding units is not limited to three, and may be any plural number.

  FIG. 8 shows another modified example of the polishing / dressing unit. The same reference numerals are given to the same parts as those in FIG. 7, and the detailed description thereof will be omitted. In this example, the tool / wafer holders 30A, 30B, and 30C are moved by independently swinging the rotary shafts 38A, 38B, and 38C in the directions of arrows a, a ′, b, b ′, and c, c ′, respectively. It is configured to swing independently of each other.

  FIG. 9 shows still another modified example of the polishing / dressing unit. The same reference numerals are given to the same parts as those in FIG. 7, and the detailed description will be omitted. In this example, a connecting portion 42 for connecting the rotating shafts 38A to 38C is provided, and the tool / wafer holding portions 30A to 30C are swung in conjunction with each other by swinging the connecting portion 42 in the directions of arrows S and S ′. It is a configuration.

  8 and 9, in addition to the effect of improving the throughput, the effect of improving the dressing uniformity and the polishing efficiency can be obtained in the same manner as the polishing / dressing unit described in FIG.

  The present invention is not limited to the above-described embodiment, and can be implemented in various modifications. For example, in the embodiment shown in FIG. 4 or 5, the rotary shaft 38 b connected to the grinding tool 36 can be moved up and down, and the grinding tool 36 is lowered at an appropriate time to add a grindable dressing. Good.

1 is a perspective view showing a polishing apparatus according to an embodiment of the present invention. It is sectional drawing which shows the tool wafer holding | maintenance part of the apparatus of FIG. It is sectional drawing which shows the modification of a tool wafer holding part. It is sectional drawing which shows the tool wafer holding part which concerns on other embodiment of this invention. It is sectional drawing which shows the modification of a tool wafer holding part. It is a perspective view which shows the grinding | polishing apparatus which concerns on further another embodiment of this invention. It is a perspective view which shows the modification of a grinding | polishing and dressing part. It is a perspective view which shows the other modification of a grinding | polishing and dressing part. It is a perspective view which shows the further another modification of a grinding | polishing and dressing part. It is a side view which shows the wafer mounting process in the conventional grinding | polishing process. FIG. 11 is a side view showing a wafer holding step following the step of FIG. 10. FIG. 12 is a side view showing a wafer moving process subsequent to the process of FIG. 11. FIG. 13 is a side view showing a wafer lowering and wafer polishing step following the step of FIG. 12. It is a side view which shows the wafer raising process following the process of FIG. FIG. 15 is a side view showing a wafer movement and wafer removal step subsequent to the step of FIG. 14. FIG. 16 is a side view showing a wafer holding unit returning step subsequent to the step of FIG. 15. It is a side view which shows the polishing cloth dressing process following the process of FIG. It is sectional drawing which shows the conventional wafer holding part.

Explanation of symbols

  10: Main body, 12: Surface plate, 12a: Polishing cloth, 14: Wafer receiver, 16: Wafer, 30, 30A-30C: Tool / wafer holding part, 32: Discharge part, 34: Guide, 36: Grinding tool, 37 : Brush, 38, 38A to 38C, 38a, 38b: rotating shaft, 40: dropping nozzle.

Claims (4)

Abrasive cloth is fixed to the surface of the surface plate that can be rotated,
While holding the object to be polished by the holding part,
A polishing method for polishing by pressing the polishing cloth while rotating the surface plate while rotating the object held by the holding unit,
A grindable dressing tool that independently rotates around a portion that holds an object to be polished in the holding portion,
Furthermore, another dressing tool of a different type from the dressing tool is provided,
A polishing method comprising: dressing the polishing cloth by independently rotating and driving these different kinds of dressing tools in parallel with polishing of an object to be polished. The polishing method of claim 1 wherein the dressing said polishing cloth by driving independently rotating said dressing tool and the holding portion. The polishing method according to claim 1, wherein the holding portion is swung while being rotated. And vertically movable rotary shaft connected to the grinding of the dressing tool, timely lowers the grindability of the dressing tool of claims 1 to add the dressing grindability to any one of claims 3 The polishing method described.

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