KR100854422B1 - Apparatus for grinding wafer - Google Patents

Abstract

A wafer polishing apparatus is provided to prevent the pores of a chuck table from being stopped up by preventing sludge from being introduced into a gap between the chuck table and a wafer. A wafer polishing apparatus includes a rotatable turntable and a plurality of chuck tables for adsorbing a wafer to be polished wherein the plurality of chuck tables are installed along the circumferential direction of the upper surface of the turntable. At least one of the plurality of chuck tables includes a table body(71) having a vacuum line, a porous chuck body(73) formed on the table body wherein the porous chuck body has a plurality of poros connected to the vacuum line, and a sludge introduction preventing part(75) for preventing sludge from being introduced into a gap between the porous chuck body and the wafer. The sludge introduction preventing part is installed near the porous chuck body, separated from the porous chuck body. An air injection hole can be formed in the table body to inject sludge introduction preventing air to an edge region of the wafer.

Description

Wafer Grinding Equipment {Apparatus for grinding wafer}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly, to a wafer polishing apparatus capable of preventing the production of defective wafers or clogging of pores of the chuck table due to sludge introduced between the chuck table and the wafer. .

In the wafer fabrication process of forming a semiconductor integrated circuit on the active surface of the wafer, the wafers introduced into the wafer fabrication process in order to suppress damage of the wafer generated during movement or handling between the wafer fabrication apparatuses are substantially a semiconductor package. It is provided in a considerably thicker state than the wafers used in the manufacturing process.

Therefore, after the wafer fabrication process, a process of polishing one surface (rear surface) of the unnecessary wafer is involved before being provided to the semiconductor package fabrication process. Through the polishing of the back surface of the wafer, it is possible to reduce the volume of the semiconductor chip and to ensure good heat dissipation characteristics when packaged and used.

Conventional wafer polishing apparatus for polishing the back of the wafer is an apparatus for polishing the back of the wafer in the order of rough grinding, fine grinding and polishing processes.

This conventional wafer polishing apparatus includes a turntable that is rotatable, four chuck tables provided on the turntable, a wafer cassette for supply and a wafer cassette for storage provided on one side of the turntable. do. A polishing unit that performs a polishing process on the wafer adsorbed on the chuck table is installed on each of the three chuck tables.

As will be described in detail later, four chuck tables are provided for vacuum suction of wafers, and four chuck tables are provided at edge portions along the circumferential direction of the turntable, and rotate together with the turntable at predetermined angles as the turntable rotates.

At this time, the four chuck tables are divided into a standby table on which the wafer waits, a roughing table in which the roughing process is performed, a finishing table in which the finishing process is performed, and a polishing table in which the polishing process is performed.

The polishing unit is installed on the roughing table, the finishing table and the polishing table, except for the waiting table, which is a portion where the wafer is supplied or taken out. Briefly with respect to the polishing unit, the polishing unit is provided with a roughing wheel installed on the top of the roughing table to roughly polish the initial wafer rear surface, and a polishing wheel mounted on the top of the finishing table to precisely polish the back surface of the wafer where the roughing process is completed. And a polisher installed on the polishing table and polishing the back surface of the wafer, in which the finishing process is completed, by chemical mechanical polishing (CMP).

The supply wafer cassette and the storage wafer cassette are provided in proximity to the waiting table. The supply wafer cassette provides a wafer to be subjected to the back polishing process to the waiting table, and the receiving wafer cassette is provided with a wafer on which the back polishing process is completed.

In such a wafer polishing apparatus, the chuck table described above has a chuck table structure of a general vacuum method. That is, a chuck table (or a porous chuck table) having an area corresponding to the upper surface of the table body is disposed on the table body, and a smaller wafer is loaded on the chuck table and adsorbed through the vacuum line. In this case, the wafer is adsorbed through the chuck table.

By the way, in the conventional wafer polishing apparatus having such a chuck table structure, sludge flows between the chuck table and the wafer loaded thereon, causing contamination on the back grind tape (BG tape) and the deposition surface of the wafer. ), And there is a problem that the sludge is introduced between the pores of the chuck table and the pores are blocked.

SUMMARY OF THE INVENTION An object of the present invention is to provide a wafer polishing apparatus capable of preventing the production of defective wafers or clogging of pores of the chuck table due to sludge introduced between the chuck table and the wafer.

The object is, according to the present invention, a turntable rotatable; And a plurality of chuck tables provided along the circumferential direction on the turntable to adsorb wafers to be polished, wherein at least one of the chuck tables comprises: a table body having a vacuum line formed thereon; Porous chuck body having a plurality of pores in communication with the vacuum line, is provided on the table body; And a sludge inflow prevention part provided adjacent to the porosity chuck body in a state separated from the porosity chuck body in order to prevent sludge from flowing between the porosity chuck body and the wafer. Is achieved.

Here, the sludge inflow prevention unit may be a sludge inflow prevention ring in which no pores are formed.

The porosity chuck body and the sludge inflow prevention ring may be spaced apart from each other.

The porosity chuck body may support the deposition section of the wafer from below, and the sludge inflow prevention unit may support the non-deposition section of the wafer from below.

The porosity chuck body may have an area smaller than an upper surface of the table body.

It may further include an air injection hole formed in the table body for injecting air for preventing sludge inflow to the edge (edge) area of the wafer.

On the other hand, the object is, according to the present invention, a turntable rotatable; And a plurality of chuck tables provided along the circumferential direction on the turntable to adsorb wafers to be polished, wherein at least one of the chuck tables comprises: a table body having a vacuum line formed thereon; Porous chuck body having a plurality of pores in communication with the vacuum line, is provided on the table body; And an air spraying hole formed in the table body for injecting air for preventing sludge inflow into an edge region of the wafer.

The plurality of chuck tables may include: a standby table on which the wafer is waiting, a roughing table performing a rough grinding process on the wafer, a finishing table performing a fine grinding process on the wafer, and the And a polishing table for performing a polishing process on the wafer.

The plurality of chuck tables may further include a buffer table disposed around the roughing table and the finishing table to further perform at least one process selected from the roughing process and the finishing process.

According to the present invention, due to the sludge introduced between the chuck table and the wafer, it is possible to prevent the phenomenon that the defective wafer is mass produced or the pores of the chuck table are blocked.

In order to fully understand the present invention, the operational advantages of the present invention, and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings which illustrate preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the present invention will be described in detail by explaining preferred embodiments of the present invention with reference to the accompanying drawings. Like reference numerals in the drawings denote like elements.

1 is a block diagram of a wafer polishing apparatus according to a first embodiment of the present invention, Figure 2 is a schematic structural diagram of the chuck table shown in FIG.

As shown in these figures, the wafer polishing apparatus according to the present embodiment includes a turntable 10 that is rotatable, a rough polishing portion 30 that undergoes a rough grinding process, and a fine finish. The polishing polishing part 50 which performs a grinding process, and the polishing polishing part 60 which carries out a polishing process are provided.

The rough polishing unit 30, the finishing polishing unit 50, and the polishing polishing unit 60 are each provided along the circumferential direction on the turntable 10, and the backside (one surface or one side or the like) of the wafer W and the process is sequentially performed. Back surface).

Four chuck tables (not shown) are provided on the turntable 10 of the wafer polishing apparatus according to the present embodiment, and three on the top of three chuck tables except the standby table 21 among the four chuck tables. A polishing unit (not shown) is provided.

For reference, the four chuck tables without reference numerals refer to the waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61, and again with no reference numerals. The three polishing units point to the roughing wheel 32, the finishing wheel 52 and the polisher 62.

At this time, the structures of the four chuck tables are all provided in the same manner, and are provided at equal intervals along the circumferential direction of the turntable 10. Since these four chuck tables are rotated by the turntable 10, substantially four chuck tables serve as the standby table 21, the roughing table 31, the finishing table 51 and the polishing table 61. Perform. In the present embodiment, however, for convenience of description, the chuck table at the moment located in the roughing wheel 32, the finishing wheel 52, and the polisher 62 is respectively roughed table 31, finished table 51, and the like. The polishing table 61 is called.

By this logic, in the present embodiment, the roughing table 31 and the roughing wheel 32 are paired to form the rough polishing part 30, and the finishing table 51 and the finishing wheel 52 are paired. The finishing polishing unit 50 and the polishing table 61 and the polisher 62 are paired to form the polishing polishing unit 60. Each component is demonstrated sequentially.

The turntable 10 is a portion where four chuck tables are supported along the circumferential direction on the upper surface thereof. The turntable 10 may be manufactured in a disk shape. The lower portion of the turntable 10 is coupled to the table shaft 12 to form the center of rotation of the turntable 10. Although not shown in detail, the table shaft 12 is coupled to a bearing for smooth rotation.

As described above, the four chuck tables include a waiting table 21 on which the wafer W waits, a roughing table 31 on which a roughing process proceeds, a finishing table 51 on which a finishing step proceeds, It is divided into a polishing table 61 in which a polishing process is performed.

The waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61 which are four chuck tables are radially installed in the edge part along the circumferential direction on the turntable 10. As shown in FIG. At this time, the turntable 10 rotates the chuck tables collectively so that any chuck table can be positioned at the position of the neighboring chuck table by rotation, and at the same time, each step of the wafer W polishing process is performed. Allow it to proceed. That is, the four chuck tables serve as the waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61 by the rotation of the turntable 10.

Looking at the chuck table by position, it is divided into the waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61 in a clockwise direction, which are 90 degrees to each other at the center of the turntable 10. Can be placed in any position. The turntable 10 rotates by 90 degrees every predetermined time, and the rotation period of the turntable 10 may be set based on the longest running time of the wafer W polishing process.

On the other hand, the supply wafer cassette 15 and the storage wafer cassette 16 are provided on one side of the turntable 10 adjacent to the standby table 21. A conveyer 17 is provided between the standby table 21, the supply wafer cassette 15, and the storage wafer cassette 16. The wafer W to be polished can be transferred from the wafer cassette 15 for supply to the waiting table 21 by the transfer machine 17, and on the contrary, the polished wafer W is stored from the waiting table 21. Can be transferred to a wafer cassette 16 for use. For reference, when the wafer W to be polished is transferred from the wafer cassette 15 for supply to the waiting table 21 by the conveyer 17, the wafer W is aligned with an alignment means such as a camera (not shown). It may be desirable to transfer to the waiting table 21 after the process of aligning the position of the further progress.

Three polishing units are installed on the roughing table 31, the finishing table 51, and the polishing table 61, except for the waiting table 21. That is, the three polishing units are installed on the roughing table 31 to roughly polish the back surface of the initial wafer W, and are installed on the finishing table 51 to finish the roughing process. Polishing wheel 52 for precisely polishing the back surface of the wafer W, and the back surface of the wafer W, which is installed on the polishing table 61 and completed the finishing process, is polished by chemical mechanical method (CMP). And a polisher 62.

The roughing wheel 32 which forms the rough polishing part 30 together with the roughing table 31 has a particle size of 300 to 350 mesh, for example, 325 mesh, and thus the final wafer W is targeted. Roughly polish the back surface of the wafer (W) to 20 to 30㎛ thicker than the thickness.

The finishing wheel 52 forming the finishing polishing part 50 together with the finishing table 51 has a particle size of 1500 to 2500 mesh, for example 2000 mesh, and precisely polishes the rear surface of the rough polished wafer W to a target thickness. do.

The polisher 62 forming the polishing polishing portion 60 together with the polishing table 61 may also be referred to as a polishing polishing pad. The polisher 62 may be covered with a cloth-like material on its underside. Has a conventional configuration in which a slurry feed is formed. The polisher 62 mirrors the back surface of the finely polished wafer W to the final thickness using the slurry.

On the other hand, when roughing, finishing, and polishing processes are performed by the rough polishing unit 30, the finishing polishing unit 50, and the polishing polishing unit 60, sludge which is an abrasive corresponding to each process is provided. However, if such sludge flows between the chuck table and the wafer W loaded thereon, it may cause contamination of the back grind tape (BG Tape) and the deposition surface of the wafer W, which may cause defects (die cracks). In addition, since the pores of the chuck table may be blocked, it is necessary to prevent this. This can be solved by the structure of FIG. 2 which will be described below. For reference, the structure of FIG. 2 is applied to all the chuck tables of the waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61.

As shown in FIG. 2, the chuck table, which may be the waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61, has a large table body 71 and a porous. ) Chuck body 73, and the sludge inflow prevention portion (75).

The table body 71 forms the lower region of the chuck table. For reference, instead of forming the table body 71, a portion of the turntable 10 may be used as the table body 71. The vacuum line 71a is formed in the center region of the table body 71. Since the vacuum is formed in the direction of FIG. 2A through the vacuum line 71a, the wafer W may be adsorbed and supported on the upper surface of the POSOS chuck body 73.

The POROS chuck body 73 is provided in the upper region of the table body 71. Substantially, the wafer W is adsorbed and supported on the upper surface of the POROS chuck body 73. The wafer W is formed with a plurality of pores 73a communicating with the vacuum line 71a in the POROS chuck body 73 so as to be adsorbed and supported on the top surface of the POROS chuck body 73. Thus, a vacuum is formed in the direction of (a) of FIG. 2 through the vacuum line (71a) to suck the air in the direction (a) through a plurality of pores (73a) loading on the upper surface of the poros chuck body (73) ) The wafer W may be adsorbed. At this time, the POROUS chuck body 73 is manufactured to have an area smaller than the upper surface of the table body 71.

On the other hand, the sludge inflow prevention part 75 is adjacent to the porosity chuck body 73 in a state separated from the porosity chuck body 73 to prevent sludge from flowing between the porosity chuck body 73 and the wafer W. To be prepared. While a plurality of pores 73a are formed in the POROS chuck body 73, the pores (not shown) are not formed in the sludge inflow prevention part 75. In the present embodiment, the sludge inflow prevention part 75 is applied to the sludge inflow prevention ring 75.

As such, the porous chuck body 73 in which the pores 73a are formed and the sludge inflow prevention part 75 in which no pores (not shown) are formed are supported to support the wafer W in a state in which the pores 73a are formed in a separated state. Sludge is introduced between the porosity chuck body 73 and the wafer (W) can be prevented.

In particular, in the wafer W, the deposition section W1, which is a portion where the deposition film is to be formed, is supported on the upper surface of the porosity chuck body 73, and the non-deposition section W2 is disposed on the upper surface of the sludge inflow prevention portion 75. Since it is supported, even if the sludge penetrates into the lower part of the wafer W, it falls between the separated porosity chuck body 73 and the sludge inflow prevention part 75. Therefore, the phenomenon in which sludge flows between the porosity chuck body 73 and the wafer W can be prevented, so that a defective wafer can be mass-produced or the pores 73a of the porosity chuck body 73 are blocked. .

On the other hand, as described above, even if the porosity chuck body 73 in which the pores 73a are formed and the sludge inflow prevention portion 75 in which no pores (not shown) are formed are separated from each other, sludge is produced. Phenomenon that flows between the porous chuck body 73 and the wafer W can be prevented.

However, in addition to the above structure, when the air injection hole 72 is further provided in the table body 71, it may be more advantageous to prevent the sludge from flowing between the porosity chuck body 73 and the wafer W. .

That is, as shown in Figure 2, after the air injection hole 72 is provided in the table body 71 at the position corresponding to the edge (edge) region of the wafer (W), the polishing operation of Figure 2 (b) When the air is injected in the direction, the sludge is more difficult to flow between the porosity chuck body 73 and the wafer (W) due to the air injected.

For reference, in this embodiment, the porosity chuck body 73 in which the pores 73a are formed, and the sludge inflow prevention part 75 in which the pores (not shown) are not formed are separated from each other, and the air spray hole 72 is formed. Is applied together. However, since the scope of the present invention is not limited thereto, the porosity chuck body 73 in which the pores 73a are formed, and the sludge inflow prevention part 75 in which the pores (not shown) are not formed are separated from each other. , The air injection hole 72 may be applied to each individually.

The operation of the wafer polishing apparatus having such a configuration will be described below.

First, the conveyer 17 grips the wafer W from the supply wafer cassette 15 and transfers it to the waiting table 21. In this case, as described above, the process of aligning the position of the wafer W by an alignment means such as a camera (not shown) may be further performed.

When the wafer W is positioned on the standby table 21, the turntable 10 is rotated 90 degrees clockwise with the table axis 12 as the axis. When the wafer W is positioned on the roughing table 31 by the rotation of the turntable 10, the rear surface of the wafer W is roughly polished by the roughing wheel 32.

After the back surface of the wafer W is roughly polished by the roughing wheel 32, the turntable 10 is rotated 90 degrees again, so that the wafer W is positioned on the finishing table 51 and then to the finishing wheel 52. As a result, the back surface of the wafer W is polished. Then, after the polishing process is performed by the polisher 62 by the rotation of the turntable 10 by 90 degrees, the wafer W, which has been polished, is again placed on the standby table 21. The wafer W located on the waiting table 21 is finally transferred to the storage wafer cassette 16 through the conveyor 17.

On the other hand, even when the sludge used during the series of polishing operations penetrates into the lower portion of the wafer W, the sludge falls between the separated porosity chuck body 73 and the sludge inflow preventing portion 75, so that the sludge is in the porosity chuck body 73. ) And the phenomenon flowing between the wafer (W) can be prevented to prevent the phenomenon that the defective wafer is mass-produced or the pores (73a) of the porosity chuck body 73 is blocked.

In addition to this, if the air injection hole 72 is applied, the porosity chuck body 73 is sludge due to the air is injected by the air is injected in the direction of Fig. 2 (b) through the air injection hole 72 during the polishing operation ) More difficult to enter between the wafer and the wafer (W).

As described above, in this embodiment, due to the sludge introduced between the chuck table and the wafer W, the defective wafer is mass produced or the pores 73a of the chuck table can be blocked.

3 to 5 are each a schematic view of a wafer polishing apparatus according to the second to fourth embodiments of the present invention.

In the wafer polishing apparatus of the above-described embodiment, four chuck tables including the waiting table 21, the roughing table 31, the finishing table 51, and the polishing table 61 were provided, thereby roughing, finishing and As the polishing process progressed, the back surface of the wafer W was polished.

However, as shown in FIGS. 3 and 4, the wafer polishing apparatus may be provided with a total of five chuck tables, and as shown in FIG. 5, a total of six chuck tables may be provided. This is explained further.

In the case of FIG. 3, a total of five chuck tables include a waiting table 21, a roughing table 31, a buffer table 41, a finishing table 51 and a polishing table 61. 41) proceeds with the second roughing process. That is, according to FIG. 3, the back surface of the wafer W is polished by the first roughing, the second roughing, the finishing and the polishing process. According to FIG. 3, the roughing process with the longest processing time is divided into a plurality of processes, thereby increasing the overall wafer W rear surface polishing process time according to the time difference between the processes of the rear surface polishing process of the wafer W. There is an advantage that can be prevented to reduce the tact time.

In the case of FIG. 4, a total of five chuck tables are provided as in FIG. 3, but in the case of FIG. 4, the five chuck tables include a waiting table 21, a roughing table 31, a finishing table 51, and a buffer table 41a. ) And a polishing table 61. At this time, the buffer table 41a performs a secondary finishing process. As shown in FIG. 4, when the buffer table 41a performs the secondary finishing process, the wafer W positioned on the waiting table 21 is roughed and subjected to the primary finishing process based on the rotation of the turntable 10. The backside is polished through a secondary finishing process and a polishing process. In this case, it may be advantageous to increase the machining speed of the roughing wheel 32 to perform the roughing process in the form of a high speed machining, and then to perform the ultra-precise machining by finely finishing the finishing process than the conventional method.

In the case of Figure 5 a total of six chuck tables are provided. That is, two buffer tables 41 and 41a are provided. One buffer table 41 is for the progress of the second roughing process as shown in FIG. 3, and the other buffer table 41a is for the progress of the secondary finishing process as shown in FIG. 4. In the case as shown in Figure 5 can be processed by dividing the initial roughing process with a large amount of processing, there is an advantage that can also perform fine machining than the conventional method by dividing the finishing machining.

Taken together, as shown in Figs. 3 to 5, even if the number of chuck tables is increased in the polishing apparatus, if the structure described in the first embodiment is applied, defects due to sludge introduced between the chuck table and the wafer W are applied. It is possible to prevent the phenomenon that the wafer is mass produced or the pores 73a of the chuck table are blocked.

As described above, the present invention is not limited to the described embodiments, and various modifications and changes can be made without departing from the spirit and scope of the present invention, which will be apparent to those skilled in the art. Therefore, such modifications or variations will have to be belong to the claims of the present invention.

1 is a block diagram of a wafer polishing apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic structural diagram of the chuck table shown in FIG. 1.

3 to 5 are each a schematic view of a wafer polishing apparatus according to the second to fourth embodiments of the present invention.

* Explanation of symbols for the main parts of the drawings

10: turntable 12: table axis

14 cross roller bearing 15 wafer cassette for supply

16: storage wafer cassette 17: transfer machine

21: waiting table 30: rough grinding

31: roughing table 32: roughing wheel

40: buffer polishing unit 41: buffer table

42: buffer wheel 50: finishing polishing unit

51: finishing table 52: finishing wheel

60: polishing polishing portion 61: polishing table

62: polisher 71: table body

73: poros chuck body 75: sludge inflow prevention

Claims (9)

Rotatable turntables; And A plurality of chuck tables provided along the circumferential direction on the turntable to adsorb wafers to be polished; At least one chuck table of the plurality of chuck tables, Table body formed with a vacuum line; Porous chuck body having a plurality of pores in communication with the vacuum line, is provided on the table body; And And a sludge inflow prevention part provided adjacent to the porosity chuck body in a state separated from the porosity chuck body to prevent sludge from flowing between the porosity chuck body and the wafer. The method of claim 1, The sludge inflow prevention unit is a wafer polishing device, characterized in that the sludge inflow prevention ring is not formed pores. The method of claim 2, And the porosity chuck body and the sludge inflow prevention ring are spaced apart from each other. The method of claim 1, The porosity chuck body supports the deposition section of the wafer from the bottom, and the sludge inflow prevention unit supports the non-deposition section of the wafer from the bottom. The method of claim 1, And the porosity chuck body has an area smaller than an upper surface of the table body. The method of claim 1, And an air spraying hole formed in the table body and spraying air for preventing sludge inflow into an edge region of the wafer. Rotatable turntables; And A plurality of chuck tables provided along the circumferential direction on the turntable to adsorb wafers to be polished; At least one chuck table of the plurality of chuck tables, Table body formed with a vacuum line; Porous chuck body having a plurality of pores in communication with the vacuum line, is provided on the table body; And And an air spraying hole formed in the table body to inject air for preventing sludge inflow into an edge region of the wafer. The method according to claim 1 or 7, The plurality of chuck tables may include a standby table on which the wafer is waiting, a roughing table performing a rough grinding process on the wafer, a finishing table performing a fine grinding process on the wafer, and the wafer. Wafer polishing apparatus comprising a polishing table for performing a polishing (polishing) process for. The method of claim 8, The plurality of chuck tables further include a buffer table disposed around the roughing table and the finishing table to further perform at least one process selected from the roughing process and the finishing process. Device.

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