KR20060089801A - Wafer back grinding apparatus - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer backside polishing apparatus. In order to suppress the length of the wafer backside polishing process even if the amount of wafer backside polishing increases due to the thinning of the semiconductor package, Chuck table; A turntable in which the chuck tables are radially installed at an edge portion and collectively rotate the chuck tables so that any chuck table can be rotated and positioned in a neighboring chuck table; And a grinder which is installed on each of the chuck tables except for the chuck table on which the loading / unloading of the wafer proceeds and simultaneously performs each step of the wafer backside polishing process on the wafer fixed to the chuck table. The table may include: a waiting table in which a wafer on which a wafer alignment step is completed is mounted and waiting, or a wafer on which a wafer backside polishing process is completed is located; A roughing table installed adjacent to the waiting table and undergoing a roughing step for the wafer on which the alignment step is completed; A finishing table installed adjacent to the roughing table and performing a finishing step on the wafer on which the roughing step is completed; A polishing table installed between the finishing table and the waiting table, the polishing table of which a polishing step is performed on the wafer on which the finishing step is completed; And at least one buffer table disposed between the roughing table and the finishing table, wherein at least one buffer table is processed at least with an increased amount of polishing on the wafer back surface.

Wafer, Back, Polishing, Polishing, Roughing, Finishing, Buffer

Description

Wafer back grinding apparatus

1 is a plan view showing a wafer backside polishing apparatus according to the prior art.

FIG. 2 is a flowchart illustrating a wafer backside polishing method using the wafer backside polishing apparatus of FIG. 1.

3 is a plan view showing a wafer backside polishing apparatus according to an embodiment of the present invention.

4 is a flowchart illustrating a wafer backside polishing method using the wafer backside polishing apparatus of FIG. 3.

Description of the main parts of the drawing

110: wafer cassette for supply 120: wafer transfer machine

130: turntable 141: standby table

143: roughing table 144: buffer table

145: finishing table 147: polishing table

153: roughing machine 154: buffer grinding machine

155: Finishing Machine 157: Polisher

160: storage wafers 171, 173, 174, 175, 177: wafer

200: back wafer polishing apparatus

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wafer polishing apparatus, and more particularly, to a wafer backside polishing apparatus for polishing a backside of a wafer to thinly process the wafer.

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

Therefore, after the wafer fabrication process, the process of polishing the rear portion of the unnecessary wafer is performed before being provided to the semiconductor package fabrication process. The wafer backside polishing process can reduce the volume of semiconductor chips and ensure good heat dissipation characteristics when packaged and used.

As shown in FIG. 1, the wafer backside polishing apparatus 100 according to the related art, which performs the backside polishing process as described above, proceeds in the order of rough grinding, fine grinding, and polishing. As a device for polishing a wafer back surface, a wafer cassette 10 for supply and a storage side are provided on one side of a turntable 30 provided with four chuck tables 41, 43, 45, and 47. Wafer cassette 60 is installed. Then, the polishing machines 53, 55, 57 which perform the polishing process on the wafers 71, 73, 75, 77 adsorbed to the chuck tables 41, 43, 45, 47 are three chuck tables 43, 45, 47) are installed on top of each other.

The chuck tables 41, 43, 45, 47 are vacuum suction portions of the wafers 71, 73, 75, 77, and four are provided at the edges of the turntable 30, and the rotation of the turntable 30 is performed. Together, they rotate at a predetermined angle. At this time, the chuck tables 41, 43, 45, and 47 have a waiting table 41 on which the wafer 71 waits according to the position, a roughing table 43 on which the roughing step proceeds, and a finishing table 45 on which the finishing step proceeds. ) And the polishing table 47 in which the polishing step is performed, and the waiting table 41, the roughing table 43, the finishing table 45, and the polishing table 47 are located in the clockwise direction.

Polishers 53, 55, 57 are provided on the roughing table 43, the finishing table 45, and the polishing table 47, except for the waiting table 41. The grinders 53, 55, and 57 are provided on the roughing table 43 to roughly polish the back surface of the initial wafer 73, and the wafers on which the roughing step is completed. (75) A polishing machine 55 for precisely polishing the rear surface, and a polishing machine for polishing the back surface of the wafer 77 installed on the polishing table 47 and completing the finishing step by chemical mechanical polishing (CMP). And a polisher 57.

The wafer cassette 10 for supplying and the wafer cassette 60 for storing are provided in proximity to the waiting table 41 to provide the wafer 71 to the waiting table 41 for the back grinding process, and to perform the wafer back polishing process. This completed wafer is provided. At this time, the wafer transfer between the waiting table 41 and the wafer cassettes 10 and 60 is performed by the wafer transfer machine 20. Before the wafer 71 is transferred from the wafer cassette 10 for supply by the wafer feeder 20 to the waiting table 41, the position of the wafer 71 is aligned by an alignment means such as a camera (not shown). After the step is performed, it is transferred to the waiting table 41.

The wafer backside polishing method 80 using the wafer backside polishing apparatus 100 according to the related art will be described with reference to FIGS. 1 and 2. 2 is a process diagram according to the wafer backside polishing method 80 using the wafer backside polishing apparatus according to the prior art.

The wafer backside polishing process starts from the wafer loading step (81 in FIG. 2). That is, the wafer transporter 20 takes one wafer 71 from the supply wafer cassette 10 and mounts it on the waiting table 41.

At this time, the wafer alignment step of orienting the wafer 71 in order to put the wafer 71 on the standby table 41 in the correct position is preceded (82 in FIG. 2). That is, when the wafer transporter 20 pulls out one wafer 71 from the wafer cassette 10 for supply, the camera checks the position of the wafer 71 and then adjusts the wafer 71 to a position to be mounted on the waiting table 41. ) Align the position. The aligned wafers 71 are mounted on the waiting table 41 and fixed by vacuum suction.

Next, the roughing step proceeds (83 in FIG. 2). That is, as the turntable 30 rotates, the waiting table 41 to which the wafer 71 is adsorbed moves below the roughing machine 53. Then, the roughing machine 53 moves downward to rough the wafer 73 back surface. At this time, in the roughing step, the wafer 73 is roughly polished at a time shorter than the target thickness to be finally polished by 20 to 30 µm.

Next, the finishing process proceeds (85 in FIG. 2). That is, when the roughing step is completed, the roughing table 43 on which the wafer 73 on which the roughing step is completed is adsorbed moves down the finisher 55 in accordance with the rotation of the turntable 30. Then, the finishing machine 55 moves downward to finish the back surface of the wafer 75. At this time, in the finishing step, the roughed wafer 75 is precisely polished to the final thickness.

The polishing step then proceeds (87 in FIG. 2). That is, when the finishing step is completed, according to the rotation of the turntable 30, the finishing table 45 on which the wafer 75 on which the finishing step is completed is adsorbed moves under the polisher 57. Then, the polisher 57 moves downward to polish the back surface of the wafer 77. At this time, the polishing step mirrors the back surface of the wafer 77 with the polisher 57 while supplying a slurry to reduce warpage of the finished wafer 77 and increase the strength of the semiconductor chip. .

The cleaning step then proceeds (88 in FIG. 2). That is, after the polishing step is completed, a step of cleaning using ultrapure water is performed to remove the polishing liquid and the debris generated in the polishing step. At this time, the cleaning step is performed while the polishing table 77 of the wafer 77 on which the polishing step is completed moves to the standby position according to the rotation of the turntable 30.

Finally, the unloading of the wafer proceeds (89 in FIG. 2). That is, the wafer on which the cleaning step is completed is placed on the waiting table 41. Then, the wafer transfer machine 20 transfers the wafer on the waiting table 41 and stores it in the wafer cassette 60 for storage. Here, before storing the wafer on the waiting table 41 in the storage wafer cassette 60, it is preferable to proceed with the step of cleaning the wafer once again.

In this case, the above-described wafer backside polishing process has been described as an example of a stepwise progression according to the stepwise rotation of the turntable 30, but simultaneously proceeds on the turntable 30, and substantial wafer backside polishing is almost performed in the roughing and finishing steps.

Meanwhile, as the thickness of the semiconductor package is accelerated, the amount of polishing on the back surface of the wafer is increasing. Increasing the amount of polishing on the backside of the wafer leads to an increase in roughing and finishing time. In order to proceed with the polishing of the backside of the wafer while minimizing time delay at each chuck table as the turntable rotates, the amount of finishing needs to be increased. There is.

However, when the finishing amount exceeds 30 µm, wafer burning occurs and the quality of the wafer is deteriorated. Therefore, the amount that can increase the finishing amount is limited.

Therefore, in consideration of such a problem, conventionally, only the roughing amount was increased, and thus the wafer backside polishing process was performed. Therefore, the roughing process time is longer than the other process time, so that the overall wafer backside polishing time is longer and the production yield of the wafer backside polishing device decreases. Was generated.

Accordingly, it is an object of the present invention to prevent the overall wafer backside polishing process time from being longer due to the time difference between the steps of the wafer backside polishing process.

In order to achieve the above object, the present invention is to provide a wafer rear surface polishing apparatus further comprising a buffer polishing portion capable of processing at least the increased polishing amount in accordance with the increase of the wafer rear surface polishing amount.

In a preferred embodiment of the present invention, a plurality of chuck tables are mounted and fixed so that a wafer backside faces upward; A turntable in which the chuck tables are radially installed at an edge portion and collectively rotate the chuck tables so that any chuck table can be rotated and positioned in a neighboring chuck table; And a grinder which is installed on each of the chuck tables except for the chuck table on which the loading / unloading of the wafer is performed and simultaneously performs each step of the wafer backside polishing process on the wafer fixed to the chuck table.

The chuck table may include: a waiting table on which a wafer on which a wafer alignment step has been completed is mounted and waiting or a wafer on which a wafer backside polishing process is completed is located; A roughing table installed adjacent to the waiting table and undergoing a roughing step for the wafer on which the alignment step is completed; A finishing table installed adjacent to the roughing table and performing a finishing step on the wafer on which the roughing step is completed; A polishing table installed between the finishing table and the waiting table, the polishing table of which a polishing step is performed on the wafer on which the finishing step is completed; And at least one buffer table disposed between the roughing table and the finishing table, wherein at least one buffer table is processed at least with an increased amount of polishing on the wafer back surface.

In the present invention, the grinding machine is provided on the rough table to roughly polish the wafer rear surface of the rough table, and the buffer polisher is installed on the buffer table upper to polish the wafer rear surface of the buffer table upper portion at least by an increased amount of wafer polishing. And a finisher installed at the top of the finishing table to precisely polish the back surface of the wafer on which the buffer polishing step is completed, and a polisher chemically and mechanically polishing the back side of the wafer at the top of the polishing table.

And in the present invention, the buffer polishing machine may be a roughing machine or a finishing machine.

Hereinafter, with reference to the accompanying drawings will be described in detail an embodiment of the present invention.

3 is a plan view illustrating a wafer backside polishing apparatus 200 according to an embodiment of the present invention. Referring to FIG. 3, the wafer backside polishing apparatus 200 is an apparatus for polishing a backside of a wafer in the order of roughing, finishing and polishing, and includes a turntable provided with a plurality of chuck tables 141, 143, 144, 145, and 147. The wafer cassette 110 for supplying and the wafer cassette 160 for storing are installed in one side about 130. In addition, the polishing machines 153, 154, 155, and 157 which perform the polishing process on the wafers 171, 713, 174, 175, and 177 adsorbed to the chuck tables 141, 143, 144, 145, and 147 are provided with a chuck table ( 141, 143, 144, 145, 147 are respectively installed.

In particular, the wafer backside polishing apparatus 200 according to the embodiment of the present invention includes a buffer polishing portion capable of processing at least the increased polishing amount according to the increase of the backside polishing amount according to the thinning demand of the wafer. Therefore, the wafer backside polishing apparatus 200 according to the embodiment of the present invention may further include a buffer polishing portion, thereby preventing the wafer backside polishing process time from being increased due to the increased polishing amount.

Referring to the wafer backside polishing apparatus 200 according to the embodiment of the present invention in detail, a plurality of chuck tables 141, 143, 144, 145, and 147 are radially installed at the edges of the upper surface of the turntable 130. do. At this time, the turntable 130 rotates and moves the chuck tables 141, 143, 144, 145, and 147 collectively so that any chuck table can be positioned to the neighboring chuck table by rotation. Allow each step to proceed.

The chuck tables 141, 143, 144, 145, and 147 are vacuum suction parts of the wafers 171, 713, 174, 175, and 177 mounted with the back side facing upwards, when the wafer backside polishing process is completed. The wafers 171, 713, 174, 175, and 177 are adsorbed in vacuo until then. The chuck tables 141, 143, 144, 145, and 147 may be divided into a waiting table 141, a roughing table 143, a finishing table 145, and a polishing table 147 according to positions, and wait in a clockwise direction. A table 141, a roughing table 143, a finishing table 145, and a polishing table 147. In an embodiment of the present invention, a buffer of a buffer grinding portion provided between the roughing table 143 and the finishing table 145 is provided. The table 144 is further installed.

For example, five chuck tables 141, 143, 144, 145, 147, that is, a waiting table 141, a roughing table 143, a buffer table 144, and a finishing table 145 around the edge of the upper surface of the turntable 130. And a polishing table 147 are installed, and the five chuck tables 141, 143, 144, 145, and 147 move from the center of the turntable 130 to move to the neighboring chuck table according to the rotation of the turntable 130. Installed at a position capable of forming 72 degrees with each other, the turntable 130 rotates 72 degrees every predetermined time. The rotation period of the turntable 130 is set based on the longest time of the wafer backside process.

The waiting table 141 is equipped with a wafer 171 on which a wafer alignment step is completed, and waits, or a wafer on which wafer back polishing is completed. At this time, the wafer cassette 110 for supplying and the wafer cassette 160 for storing are provided in proximity to the waiting table 141 to provide the wafer 171 to the waiting table 141 for the back grinding process, and the wafer back polishing process. This completed wafer is provided. Transfer of the wafer between the waiting table 141 and the wafer cassettes 110, 160 is performed by the wafer transferr 120. Before the wafer 171 is transferred from the wafer cassette 110 for supply to the waiting table 141 by the wafer transporter 120, the waiting table 141 after the step of aligning the position of the wafer 171 with the camera is performed. Is transferred to).

The roughing table 143 is installed adjacent to the waiting table 141 and is a portion where the roughing step for the wafer 173 in which the alignment step is completed is performed. At this time, the roughing machine 153 which performs the roughing step is installed at the upper part of the roughing table 153. As the roughing machine 153, a spindle motor in which a diamond wheel is installed may be used.

The buffer table 144 is installed adjacent to the roughing table 143 and is a portion where wafer backside polishing is performed by at least an increased wafer polishing amount. In this case, a buffer grinder 154 for performing a buffer polishing step is installed on the buffer table 144. As the buffer polishing machine 154, a roughing machine or a finishing machine may be used as necessary. Here, the buffer table 144 and the buffer polishing machine 154 constitute a buffer polishing portion.

Meanwhile, in the exemplary embodiment of the present invention, an example in which one buffer table 144 is installed is disclosed, but one or more buffer tables may be provided as necessary. Of course, the buffer polishing machine is installed on the buffer table.

The finishing table 145 is installed adjacent to the buffer table 144 and is a portion where the finishing of the wafer 175 on which the buffer polishing step is completed is performed. At this time, the finishing machine 155 for performing the finishing step is installed at the top of the finishing table 145. As the finishing machine 155, a spindle motor in which a diamond wheel is installed may be used in the same manner as the roughing machine 153. When compared to the roughing machine 153, there is a difference only in the grain size of the diamond abrasive grains of the diamond wheel.

The polishing table 147 is installed between the finishing table 145 and the waiting table 141 and is a portion where the polishing step for the wafer 177 on which the finishing step is completed is performed. In this case, a polisher 157 that performs a polishing step is installed at an upper portion of the polishing table 147. The polisher 157 polishes the back surface of the wafer 177 by the CMP method to reduce warpage of the finished wafer 177 and increase the strength of the semiconductor chip.

Although not shown, deionized water is sprayed onto the wafer 177 and the polishing table 147 when the polishing table 147 moves to the standby position by a scrubber provided at an upper portion between the polishing table 147 and the waiting table 141. To clean.

At this time, steps performed in each chuck table 141, 143, 144, 145, and 147 are simultaneously performed on the turn table 130, and the chuck table is sequentially moved to a neighboring chuck table by the rotation of the turn table 130. The wafer backside polishing process proceeds.

The wafer backside polishing method 180 using the wafer backside polishing apparatus 200 according to the present invention will be described with reference to FIGS. 3 and 4. 4 is a process chart according to the wafer backside polishing method 180 using the wafer backside polishing apparatus of FIG. 3.

The wafer backside polishing process starts from the wafer loading step (181 of FIG. 4). That is, the wafer transporter 120 takes out one wafer 171 from the supply wafer cassette 110 and mounts it on the waiting table 141.

At this time, the wafer alignment step of orienting the wafer 171 to place the wafer 171 on the standby table 141 in the correct position is preceded (182 in FIG. 2). That is, when the wafer transporter 120 takes out one wafer 171 from the wafer cassette 110 for supply, the camera checks the position of the wafer 171 and then adjusts the wafer 171 to a position to be mounted on the waiting table 141. ) Align the position. The aligned wafers 171 are mounted on the waiting table 141 and fixed by vacuum suction.

Next, the roughing process proceeds (183 of FIG. 4). That is, as the turntable 130 rotates, the standby table 141 to which the wafer 171 is adsorbed moves below the roughing machine 153. Then, the roughing machine 153 moves downward to rough the wafer 173 rear surface.

The buffer polishing step then proceeds (184 of FIG. 4). That is, when the roughing step is completed, the roughing table 143 to which the wafer 173 on which the roughing step is completed is adsorbed moves under the buffer polishing machine 154 according to the rotation of the turntable 130. The buffer polisher 154 moves downward to polish the back surface of the wafer 174 by the amount of buffer polishing.

Next, the finishing process proceeds (185 of FIG. 4). That is, when the buffer polishing step is completed, the buffer table 144 on which the wafer 174 on which the buffer polishing step is completed is adsorbed moves under the finisher 155 according to the rotation of the turntable 130. The finisher 155 moves downward to finish the rear surface of the wafer 175. In this case, the finishing step is a process of precisely polishing the wafer 175 to which the buffer polishing step is completed to the final thickness.

At this time, the buffer polishing step may proceed to the roughing step to supplement the roughing step or to the finishing step to supplement the finishing step. That is, this can be solved by increasing the rough polishing amount or the finishing polishing amount with respect to the increased wafer polishing amount as described in the prior art. In the embodiment of the present invention, at least the increased wafer polishing amount is processed in the buffer polishing step.

First, in order to process the increased wafer polishing amount by increasing the rough polishing amount, the total rough polishing amount to be processed is divided into roughing and buffer polishing steps, thereby increasing the wafer backside polishing time even if the roughing polishing amount is increased. Can be prevented. At this time, the roughing step and the buffer polishing step are preferably polished to 20 to 30㎛ smaller than the target thickness to the final polishing.

Alternatively, in the case of processing the increased polishing amount by increasing the finishing polishing amount, the total finishing polishing amount to be treated is divided into the buffer polishing step and the finishing step, so that even if the total finishing polishing amount is increased, wafer burning and wafer backside polishing time is increased. This can be prevented from lengthening. At this time, it is preferable to adjust the total finishing polishing amount not to exceed 60㎛.

Alternatively, the buffer polishing step may be performed using a diamond wheel having a grain size of diamond abrasive grains between the rougher and the finisher as the buffer polisher 174.

Next, the polishing step proceeds (187 of FIG. 4). That is, when the finishing step is completed, the finishing table 145 to which the wafer 175 on which the finishing step is completed is adsorbed moves under the polisher 157 according to the rotation of the turntable 130. Then, the polisher 157 moves downward to polish the back surface of the wafer 177. At this time, the polishing step mirror-mirrors the back surface of the wafer 177 with a polisher while a polishing liquid is supplied to reduce warping of the finished wafer 177 and increase the strength of the semiconductor chip.

The cleaning step then proceeds (188 in FIG. 4). That is, after the polishing step is completed, a step of cleaning using ultrapure water is performed to remove the polishing liquid and the debris generated in the polishing step. At this time, while the polishing table 147 of the wafer 177 on which the polishing step is completed moves to the standby position according to the rotation of the turntable 130, the cleaner sprays ultrapure water to clean the polishing table 147 together with the wafer 177. do.

Finally, the unloading of the wafer proceeds (189 in FIG. 4). That is, the wafer on which the cleaning step is completed is placed on the waiting table 141. The wafer transporter 120 transports the wafer on the waiting table 141 and stores the wafer on the storage wafer cassette 160. Here, before storing the wafer on the waiting table 141 in the storage wafer cassette 160, the wafer is cleaned once more. Then, a new wafer is taken out from the supply wafer cassette 110, and the wafer aligned is transferred to the waiting table.

In this case, although the above-described wafer back polishing process is described as being performed step by step in accordance with the stepwise rotation of the turntable 130, it proceeds simultaneously on the turntable 130.

On the other hand, the embodiments of the present invention disclosed in the specification and drawings are merely presented specific examples to aid understanding, and are not intended to limit the scope of the present invention. In addition to the embodiments disclosed herein, it is apparent to those skilled in the art that other modifications based on the technical idea of the present invention may be implemented.

Therefore, according to the structure of the present invention, at the wafer polishing process between the roughing machine and the finishing machine, at least the increased polishing amount according to the increase of the wafer backside polishing amount according to the thinning demand of the wafer is processed. It is possible to prevent the backside polishing process time from lengthening.

Claims (4)

A plurality of chuck tables mounted and fixed so that the wafer backside is upward; A turntable in which the chuck tables are radially installed at an edge portion and collectively rotate the chuck tables so that any chuck table can be rotated and positioned in a neighboring chuck table; And a grinder which is installed on each of the chuck tables except for the chuck table on which the loading / unloading of the wafer is performed and simultaneously performs each step of the wafer backside polishing process on the wafer fixed to the chuck table. The chuck table is, A waiting table on which a wafer on which a wafer alignment step has been completed is mounted and waiting or where a wafer on which a wafer backside polishing process is completed is located; A roughing table installed adjacent to the waiting table and undergoing a roughing step for the wafer on which the alignment step is completed; A finishing table installed adjacent to the roughing table and performing a finishing step on the wafer on which the roughing step is completed; A polishing table installed between the finishing table and the waiting table, the polishing table of which a polishing step is performed on the wafer on which the finishing step is completed; And at least one buffer table disposed between the roughing table and the finishing table, wherein at least one buffer table is processed at least in accordance with an increase in the amount of polishing of the wafer back surface. The polishing machine of claim 1, wherein A roughing machine installed on the roughing table and roughly polishing a wafer rear surface of the roughing table; A buffer polisher mounted on the buffer table to polish at least the increased wafer polishing amount on the back surface of the wafer on the buffer table; A finishing machine installed on the finishing table to precisely polish the back surface of the wafer on which the buffer polishing step is completed; And a polisher installed on the polishing table to chemically and mechanically polish the back surface of the wafer on which the finishing step is completed. The wafer backside polishing apparatus according to claim 2, wherein the buffer polishing machine is a roughing machine. The wafer backside polishing apparatus according to claim 2, wherein the buffer polishing machine is a finishing machine.

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