JPH08250457A - Vertical wafer polishing device - Google Patents

Abstract

PURPOSE: To provide a vertical wafer polishing device which can improve the flatness accuracy and cleaning efficiency of wafers and, at the same time, can be reduced in occupying space. CONSTITUTION: A wafer W to be polished is pressed against a vertical polishing turntable covered with a piece of polishing cloth while the wafer W is vertically held by means of a suction pad 32. The wafer W is polished by relatively rotating the turntable 30 with respect to the pad 32 in a state where the wafer W is slidden on the cloth 36 while slurry is supplied to the space between the pad 32 and polishing surface of the turntable 30. Since the slurry easily flows down, the polishing dust discharging function of the slurry is improved and the scratching of the wafer W by the polishing duct can be prevented. In addition, the flatness accuracy and polishing efficiency of the wafer are also improved. In addition, the cleaning solution can be easily removed from cleaning means 52, 53, and 54, drying means 56, and wafer carrying system 14 between processes after the wafer W is cleaned, because the wafer W is maintained in a vertical attitude.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertical type wafer polishing apparatus, and more particularly to a vertical type wafer polishing apparatus for performing polishing in a flattening process corresponding to multi-layering of wafers by a chemical mechanical polishing method.

[0002]

2. Description of the Related Art In recent years, with the demand for higher integration of semiconductor elements, the density of wafers and the number of layers have increased, and the depth of focus of exposure apparatuses for forming circuit wiring patterns on wafers has become shallow. Therefore, the flatness of the wafer to be the exposed surface is required with high accuracy, and the chemical mechanical polishing method (CMP) is used as a method for realizing highly accurate flattening. A conventional wafer polishing apparatus, a polishing platen and a suction pad coated with a polishing cloth are arranged horizontally facing each other, the wafer to be polished is sucked by the suction pad, and it is pressed against the polishing platen, While supplying a chemical polishing material (slurry), both are slid relative to each other to polish the wafer.

Further, a relatively hard polishing cloth is used to make the flatness per chip highly accurate. on the other hand,
As an apparatus for cleaning and drying the wafer after polishing, a single wafer cleaning apparatus capable of performing the processing steps of cleaning and drying with one apparatus has also been proposed.

[0004]

However, in the conventional wafer polishing apparatus, since the polishing platen is provided horizontally (horizontal type), the function of discharging slurry polishing chips is low, and when a hard polishing cloth is used, There is a problem that the polishing chips left on the polishing platen may scratch the surface to be polished of the wafer. That is, due to this scratch, the precision of the flattening is lowered, and the precision of the flattening cannot be improved.

Further, in order to increase the accuracy of flattening, not only the accuracy of the polishing process but also the cleaning ability after polishing must be improved. In the conventional wafer cleaning apparatus, the surface of the wafer is leveled. Since cleaning, transportation, and drying are performed while maintaining the (horizontal orientation), there is a problem that back surface cleaning of the wafer is difficult, cleaning efficiency is poor, and contaminants (dust) reattach after cleaning. There is also a problem that the cleaning liquid remains on the wafer surface and it takes time to dry.

Further, the conventional wafer polishing apparatus (horizontal wafer polishing apparatus) and cleaning apparatus have a large installation area and are not suitable for installation in a clean room where it is necessary to effectively use a limited space. The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a vertical wafer polishing apparatus for achieving high precision in flattening, improvement in cleaning efficiency, and space saving. To do.

[0007]

In order to achieve the above-mentioned object, the present invention has a suction pad for sucking and holding a wafer to be polished in a vertical vertical state, and a vertical type having a polishing surface facing the suction pad. Polishing pad, and a slurry supply means for supplying a slurry between the suction pad and the polishing surface of the polishing board, while supplying the slurry by the slurry supply means, the suction pad and the polishing board Is relatively slid relative to the wafer, and the wafer is polished in a vertical orientation.

Further, in order to achieve the above object, the present invention takes out the wafers one by one from a first wafer cassette in which a plurality of wafers are stored in a vertical posture, and conveys the wafers in a vertical posture to a suction pad described later. A first handling means, a suction pad for sucking and holding the wafer carried by the first handling means in a vertical vertical state, a vertical polishing machine having a polishing surface facing the suction pad, Slurry supply means for supplying a slurry between the suction pad and the polishing surface of the polishing board, and while supplying the slurry by the slurry supply means, the suction pad and the polishing board are relatively rotated and slid to perform polishing. The second wafer is taken out by the second handling means and the second handling means that takes out the subsequent wafer from the suction pad and conveys it in the vertical position to the cleaning means described later. And a cleaning means for immersing the wafer in a liquid in a vertical position for cleaning, a transfer means for transferring the wafer from the cleaning means to a drying means described below in a vertical position, and a cleaned wafer transferred by the transfer means. A drying unit that dries in a vertical position and a wafer that has been dried by the drying unit is taken out in a vertical position, and a second wafer cassette that can store a plurality of wafers in a vertical position is held in the vertical position. And a third handling means for carrying.

[0009]

According to the present invention, the wafer to be polished is held vertically on the suction pad and pressed against the polishing surface of the vertical polishing plate facing the suction pad. Then, while the slurry is supplied between the suction pad and the polishing surface of the polishing plate, the both are relatively rotated and slid to polish the wafer. The slurry has a function of promoting polishing and a function of discharging chips (polishing chips) generated by polishing from the contact surface. By making the polishing contact surface vertical in this way, the slurry easily flows down, and the function of discharging polishing chips is improved. As a result, it is possible to prevent the wafer from being scratched by the polishing chips, and it is possible to improve the planarization accuracy and the polishing efficiency.

According to another aspect of the present invention, not only the polishing step but also a cleaning step after polishing, a drying step after cleaning,
Also, in the wafer transfer process between the above-mentioned processes, the wafer posture is maintained in the vertical direction, and the polishing process and the cleaning process are continuously performed one by one (single wafer process). This not only enables simultaneous cleaning on both sides in the cleaning process,
After the cleaning is completed, the cleaning liquid runs out better, and the redeposition of dust is reduced. Further, even in the drying step, the washing liquid runs out well, and the drying time can be shortened. Furthermore, without changing the attitude of the wafer during the wafer transfer process,
Space-saving and smooth work flow are possible, improving processing efficiency.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a vertical wafer polishing apparatus according to the present invention will be described in detail below with reference to the accompanying drawings. FIG. 1 is a schematic perspective view showing the configuration of an embodiment of a vertical wafer polishing apparatus according to the present invention. The vertical wafer polishing apparatus 10 mainly includes a wafer polishing section 13, a wafer transfer section 14, a wafer cleaning section 16, and the like.

The wafer polishing section 13 is composed of a polishing plate 30, a polishing plate rotating motor 31, a suction pad 32, a suction pad rotating motor 33 and the like.
The polishing surface is covered with a polishing cloth 36, and the polishing surface is arranged vertically. The polishing platen 30 is rotated by a motor 31, for example, in the clockwise direction in FIG. The rotation direction is not limited to this.

On the other hand, the suction pad 32 is the polishing plate 30.
The wafer W to be polished is attracted by suction of air from the back surface and can be held in a vertical position, facing the polishing surface of the wafer. The suction pad 32 is pressed toward the polishing plate 30 while being rotated by a motor 33. A polishing amount detector (end detector) 38 is attached to the suction pad 32, and the end detector 38 is attached.
The plate thickness of the wafer W is measured with high accuracy to detect the polishing end point and to detect the polishing end timing.

The suction pad 32 is one polishing plate 30.
However, a plurality of suction pads 32 are provided in the embodiment of FIG. The suction pad 3
The number of installations of 2 is not limited to this. 4 shown in FIG.
Each of the base suction pads 32 can rotate in the counterclockwise direction in the figure, and the wafer W can be polished while the four bases revolve in the polishing plate 30. The rotation direction is not particularly limited.

Around the polishing plate 30, there are provided slurry supply ports (not shown) at a plurality of places, and during polishing of the wafer W, a slurry for promoting polishing between the sliding surfaces of the polishing plate 30 and the suction pad 32. Supplying liquid. Wafer transfer unit 14
Is a wafer loader robot 40, a carrier rail 42,
43, wafer carriers 45, 45, carrier transfer machine 4
6, 47, a wafer transfer robot 48, a wafer unloader robot 49, and the like.

The wafer loader robot 40 is configured to be movable back and forth and rotated by a known driving means, and enters the wafer cassette 50 carried into the wafer polishing apparatus 10 to take out the wafers W one by one. It can be rotated by 180 ° and conveyed to the suction pad 32. The wafer cassette 50 accommodates a plurality of unpolished wafers W in a vertical direction, and the wafer loader robot 40 maintains the wafers W accommodated in the cassette 50 in a vertical posture while W is handled on the suction pad 32.

The carrier rails 42 and 43 are arranged in parallel with each other as shown in the drawing, and the wafer carriers 45 and 45 can be moved on the carrier rails 42 and 43 by a motor or the like not shown. . Also,
The carrier transfer machines 46 and 47 are the carrier rails 4
It is connected to the carrier rails 42 and 43 so as to form a substantially quadrilateral together with the reference numerals 2 and 43.

The carrier transfer machine 46 includes a rail member 46.
A and one movable member 46B,
B is capable of holding the wafer carrier 45 and provided so as to be capable of reciprocating along the rail member 46A by a motor or the like not shown. That is, the movable member 46B holds the wafer carrier 45 that has reached the end point (lower right in the figure) of the carrier rail 42, and moves to the left end (position 46B 'in the figure) of the rail member 46A. As a result, the wafer carrier 45 can be moved along the rail member 46A.

At this time, the wafer carrier 45 can be moved without changing the attitude and orientation of the wafer W on the wafer carrier 45. Also, the rail member 4
The wafer carrier 45 that has moved to the left end of 6A moves away from the movable member 46B ', moves to the other carrier rail 43, and can move along the carrier rail 43. Thereafter, the movable member 46B 'returns to the right end of the rail member 46A (position 46B in the figure), and the next wafer carrier 4 is moved.
Move 5

The wafer carrier 45 which has reached the end point of the carrier rail 43 is transferred to the other carrier rail 42 by the carrier transfer device 47. The carrier transfer machine 47 has the same structure as the carrier transfer machine 46 and has the same function. Thus, the wafer carriers 45, 45 are guided along the substantially quadrilateral guide path constituted by the carrier rails 42, 43 and the wafer carrier transfer machines 46, 47.
Circulates in the clockwise direction in the figure.

The wafer carrier 45 has a substantially L-shaped wafer holding portion 45A for holding the wafer W, and the wafer holding portion 45A can be raised and lowered downward in the figure by a driving means (not shown). As a result, the held wafer W is transferred to the ultrasonic cleaning tank 52 and the chemical cleaning tank 5 of the cleaning unit 16.
3. The wafer W can be dropped into the high-mega water washing tank 54 and the drying tank 56, and the lowered wafer W can be pulled up. The cleaning unit 16 may be another cleaning method or means.

The wafer transfer robot 48 is constructed so as to be capable of expanding and contracting and rotating by a well-known driving means and is provided below the polishing plate 30. The wafers W after polishing are sequentially taken out from the suction pad 32. Then, the wafer is rotated by 90 ° and transferred to the wafer carrier 45 for handling.
At this time, the wafer W is kept in the vertical posture. The wafer unloader robot 49 is configured to be horizontally movable and vertically movable by a known driving means, and the drying tank 5
The wafer W that has entered the inside of 6 and has been dried can be sucked and held by air suction or the like, pulled up, and horizontally moved to be transported to the wafer cassette 60 for storing the processed wafer. At this time as well, the wafer W is maintained in the vertical orientation, and the wafer cassette 60 also accommodates the wafer W in the vertical posture.

Further, a plurality of wafer carriers 45 are provided, and polishing, cleaning and drying of a plurality of wafers W can be performed in parallel. The operation of the wafer polishing apparatus 10 configured as described above will be described. The wafer W polished by the wafer polishing apparatus 10 of FIG. 1 is formed on the silicon substrate 21 which has undergone the lapping process as shown in FIG.
Device), an aluminum wiring pattern 23 is formed, and an insulating film (SiO ₂ ) 25 is further formed on the wiring.

With the recent improvement in the resolution of the stepper (exposure) device, the pattern width d can be formed to 0.35 μm or less, and the wiring can be multi-layered (three to four layers). This multi-layering is achieved by repeating the steps of flattening the step of the vertical structure, that is, the unevenness of the insulating film 25, forming the wiring pattern 23 on the flat surface, and covering with the insulating film 25 (FIG. 2). (See (B)). The wafer polishing apparatus 10 is used in the step of flattening the unevenness of the insulating film, and is an apparatus for performing flatness per chip with high accuracy.

Now, returning to FIG. 1, the wafer cassette 50
The wafer W carried in is taken out by the wafer loader robot 40 and is carried to the polishing section 13. The back surface of the wafer W (the surface on which the electric element circuit is not formed) is adsorbed to the adsorption pad 32, and the oxide film surface 25 to be polished is brought into contact with the polishing cloth 36. Then, while supplying a mixture (slurry) of abrasive grains or powder and a working liquid (lap liquid) to the back surface and the front surface of the polishing cloth (not shown), the suction pad 32 is pressed and the suction pad spindle 33 and the polishing are performed. The disk spindle 31 is rotated to move the suction pad 32 and the polishing disk 3
Relatively move 0 and. As a result, the protrusions and depressions of the oxide film layer 25 corresponding to the wiring portions 23 are polished and removed by chemical mechanical polishing to be planarized.

At this time, polishing chips generated by polishing are easily discharged downward together with the slurry liquid, and the polishing chips do not damage the wafer W. By improving the circulation function of the slurry in this way, it becomes possible to use a harder polishing cloth as compared with the conventional horizontal type wafer polishing apparatus, and it is possible to prevent the wafer surface from being damaged by polishing chips. it can. As a result, it is possible to improve the accuracy of flattening which is required in response to the multi-layering of wafers.

Subsequently, the wafer W, which has been confirmed by the end detector 38 to reach the predetermined polishing amount, is transferred from the suction pad 32 to the wafer carrier 45 by the wafer transfer robot 48. The wafer W transferred onto the wafer carrier 45 is transferred to the ultrasonic cleaning tank 52 along the carrier rail 42.
Is carried to. Then, the holding portion 4 of the wafer carrier 45
By lowering 5A into the ultrasonic cleaning tank 52,
The wafer W is cleaned.

After washing, the holding portion 45A is raised to
The wafer W is pulled up from the ultrasonic cleaning tank 52. continue,
When the wafer carrier 45 moves and reaches the end of the carrier rail 42 (lower right in the figure), the movable member 46A of the carrier transfer device 46 holds the wafer carrier 45. Then, the movable member 46A moves along the rail member 46B while maintaining the orientation and posture of the wafer carrier 45, and transfers the wafer carrier 45 to the other carrier rail 43.

Next, the wafer W carried to the chemical cleaning tank 53 via the carrier rail 43 is transferred to the wafer carrier 45.
When the holding portion 45A of the above is lowered, it is immersed in the chemical cleaning tank 53. After cleaning, the holding part 45A is raised to lift the wafer W from the chemical cleaning tank 53. In the same manner as described above, the cleaning process by the high mega flowing water cleaning tank 54 is performed. Thus, in each cleaning step, since the wafer W is held in the vertical posture, the front surface and the back surface of the wafer W can be cleaned uniformly at the same time.

The wafer W after the high-mega water washing is carried to the drying tank 56 via the carrier rail 43, and lowered to the drying tank 56 by the holding portion 45A of the wafer carrier 45. The drying tank 56 is composed of, for example, a spin dryer, and can use the centrifugal force generated by high-speed rotation to wipe off the liquid on the surface to dry quickly. Also in this drying step, since the wafer is dried in the vertical posture, the liquid is well drained and can be dried in a short time, and the reattachment of dust can be prevented.

The wafer W that has completed the drying process is taken out of the drying tank 56 by the unloader robot 49,
It is stored in the wafer cassette 60. The emptied wafer carrier 45 is transferred to the carrier rail 42 by the carrier transfer machine 47, and is ready to carry the next wafer W. Then, the wafer processing process described above is repeated.
It should be noted that a large number of wafer carriers 45 are prepared so that the polished wafers can be processed at any time.

By thus carrying the wafer W in the vertical orientation and performing the polishing process and the cleaning process, the space can be saved and the processing efficiency can be improved.

[0033]

As described above, according to the wafer polishing apparatus of the present invention, since the suction pad for sucking the wafer to be polished and the polishing plate facing the suction pad are vertically arranged, The circulation function of the slurry supplied to the polishing contact surface is improved, and highly precise flattening is possible.

In addition to polishing, wafer transfer means,
Since the cleaning means and the drying means are provided and the wafer is kept in the vertical position even in each process, cleaning / drying efficiency can be improved, and a series of polishing, cleaning, and drying steps can be performed smoothly. Can process leaves. As a result, high throughput can be achieved. Further, space can be saved as compared with the conventional horizontal wafer polishing apparatus.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing the configuration of an embodiment of a vertical wafer polishing apparatus according to the present invention.

FIG. 2 is a schematic view of a multi-layered wafer polished by the vertical wafer polishing apparatus of FIG.

[Explanation of symbols]

 10 ... Wafer polishing apparatus 30 ... Polishing board 32 ... Suction pad 36 ... Polishing cloth 40 ... Wafer loader robot 42, 43 ... Carrier rail 45 ... Wafer carrier 46, 47 ... Carrier transfer machine 48 ... Wafer transfer robot 49 ... Wafer unloader Robot 52 ... Ultrasonic cleaning tank 53 ... Chemical cleaning tank 54 ... High mega running water cleaning tank 56 ... Drying tank 50, 60 ... Wafer cassette

Claims (3)

[Claims] 1. A suction pad for adsorbing and holding a wafer to be polished in a vertical vertical state, a vertical polishing disk having a polishing surface facing the suction pad, the suction pad and a polishing surface of the polishing disk. And a slurry supply means for supplying a slurry between, while supplying the slurry by the slurry supply means,
Relatively sliding the suction pad and the polishing plate,
A vertical wafer polishing apparatus, which polishes the wafer in a vertical orientation. 2. A first handling means for taking out the wafers one by one from a first wafer cassette in which a plurality of wafers are stored in a vertical posture and transporting the wafers to a suction pad described later in the vertical posture, and the first handling means. A suction pad for adsorbing and holding the wafer carried by the handling means in a vertical vertical state, a vertical polishing disk having a polishing surface facing the suction pad, and a suction pad and a polishing surface of the polishing disk. While supplying a slurry by a slurry supply means for supplying a slurry between the slurry supply means,
Second handling means for taking out the wafer after polishing by sliding the suction pad and the polishing plate relative to each other and carrying the wafer to the cleaning means described below in the vertical position; and the second handling means Cleaning means for immersing and cleaning the wafer carried in the vertical position in the liquid, transfer means for transferring the wafer in the vertical position from the cleaning means to the drying means described later, and the transfer means for transferring the wafer. A drying unit for drying the cleaned wafer in a vertical position, and a second wafer cassette capable of taking out the wafer dried by the drying unit in the vertical position and storing a plurality of wafers in the vertical position. And a third handling means for transporting the wafer in a vertical position, the vertical wafer polishing apparatus. 3. The vertical wafer polishing apparatus according to claim 2, wherein a plurality of said suction pads and said transfer means are provided and polishing, cleaning and drying operations are performed in parallel.