JP3680894B2 - Wafer holding method for wafer polishing apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a wafer holding method of a wafer polishing apparatus, and more particularly to a wafer holding method in a wafer polishing apparatus for polishing a semiconductor wafer by chemical mechanical polishing (CMP).
[0002]
[Prior art]
This type of semiconductor wafer polishing apparatus includes a polishing cloth and a holding head. The semiconductor wafer held by the holding head is pressed against the polishing cloth and polished while supplying slurry to the polishing cloth. Recently, a wafer polishing apparatus has been proposed in which a pressure air layer is formed between the carrier of the holding head and the semiconductor wafer, and polishing is performed while the polishing pressure is transmitted to the semiconductor wafer via the pressure air layer ( JP-A-8-339979). The holding head 15A of the wafer polishing apparatus is provided with a retainer ring 19B. The retainer ring 19B surrounds the periphery of the semiconductor wafer 13 to prevent the semiconductor wafer 13 from jumping out of the holding head 15A during polishing. Yes.
[0003]
[Problems to be solved by the invention]
However, the conventional wafer polishing apparatus that forms the pressure air layer has a drawback that the semiconductor wafer cannot be polished efficiently because the holding head cannot automatically hold the semiconductor wafer.
The present invention has been made in view of such circumstances, and in a wafer polishing apparatus for forming a pressurized air layer, a wafer polishing apparatus capable of polishing a wafer efficiently by automatically holding the wafer on a holding head. An object is to provide a wafer holding method.
[0004]
[Means for solving the problems]
The present invention is formed in order to achieve the above object, career having a suction portion for air suction of the wafer, pressing means to press toward the carrier to a polishing cloth, a pressure air layer between the carrier and the wafer pressure air layer forming hand stage to transmit to the wafer through the pressure air layer to pressing force from the pressing means and, and a holding head configured Ritenarin grayed or we surrounding the periphery of the wafer during polishing, polishing before In a wafer polishing apparatus having a wafer supply unit having a tray for storing wafers and a wafer unloading unit having a tray for storing polished wafers, the holding head and the wafer supply unit are relatively after moving in the direction approaching to, the wafer adsorption portion of the carrier projecting from said retainer ring, which is accommodated in the tray of the wafer supply portion And air suction by the adsorption unit, after moving away relatively and said holding head and the wafer supply portion, polishing cloth wafers by releasing the air suction by the suction portion of the carrier on said polishing cloth After the wafer is placed on the polishing cloth, the pressing means and the pressure air layer forming means are driven to transmit the pressing force from the pressing means to the wafer via the pressure air layer. When the polishing of the wafer is completed, the pressure air layer forming means is stopped, the polished wafer is air adsorbed by the adsorption part of the carrier, and the holding head and the wafer carry-out part are relatively after moving in the direction approaching, characterized by passing the wafer tray of the wafer unloading unit air suction by the suction portion of the carrier to release on the tray of the wafer unloading unit It is.
[0005]
According to the present invention, first, the suction part of the carrier is protruded from the retainer ring, and the wafer of the wafer supply part is air-sucked by the suction part. Thereby, according to the present invention, the wafer can be automatically held by the holding head. Next, air adsorption by the carrier adsorption unit is released on the polishing cloth, and the wafer is placed on the polishing cloth. Next, the pressing means and the pressure air layer forming means are driven, and the wafer is polished while the pressing force from the pressing means is transmitted to the wafer via the pressure air layer. When the polishing of the wafer is completed, the pressure air layer forming unit is stopped, and the polished wafer is air adsorbed by the carrier adsorbing portion. Then, air adsorption by the carrier adsorption unit is released on the wafer carry-out unit, the wafer is transferred to the wafer carry-out unit, and the wafer is transferred to the next process by the wafer carry-out unit. Thereby, this invention can grind | polish a wafer efficiently.
[0006]
DETAILED DESCRIPTION OF THE INVENTION
A preferred embodiment of a wafer holding method of a wafer polishing apparatus according to the present invention will be described below in detail with reference to the accompanying drawings.
FIG. 1 is an overall structural view showing a semiconductor wafer polishing apparatus according to an embodiment of the present invention. As shown in the figure, the wafer polishing apparatus 10 mainly includes a polishing surface plate 12, a holding head 14, a wafer supply apparatus (wafer supply section) 70, and a wafer unloading apparatus (wafer unloading section) 90.
[0007]
The polishing surface plate 12 is formed in a disk shape, and a polishing cloth 16 is provided on the upper surface thereof. A spindle 18 is connected to the lower part of the polishing surface plate 12, and the spindle 18 is connected to an output shaft (not shown) of the motor 20. The polishing platen 12 is rotated in the direction of arrow A by driving a motor 20, and slurry is supplied from a nozzle (not shown) onto the rotating polishing cloth 16.
[0008]
The holding head 14 is provided so as to be movable up and down by an elevating device (not shown), and is moved up when the semiconductor wafer to be polished is sucked and held by the holding head 14. The holding head 14 is moved downward when polishing the semiconductor wafer and presses the semiconductor wafer against the polishing cloth 16.
FIG. 2 is a longitudinal sectional view of the holding head 14. The holding head 14 shown in the figure includes a head body 22, a carrier 24, a guide ring 26, a polishing surface adjustment ring 28, a rubber sheet 30, and the like. The head main body 22 is formed in a disc shape and is rotated in the direction of arrow B in the figure by a motor (not shown) connected to the rotary shaft 32. In addition, air supply paths 34 and 36 are formed in the head main body 22. The air supply path 34 extends outside the holding head 14 as indicated by a two-dot chain line in the figure, and is connected to an air pump (AP) 40 via a regulator (R) 38A. The air supply path 36 is connected to the pump 40 via a regulator 38B.
[0009]
The carrier 24 is formed in a substantially cylindrical shape, and is arranged coaxially with the head body 22 at the lower part of the head body 22. A recess 25 is formed on the lower surface of the carrier 24, and a porous plate (adsorption part) 42 having air permeability is accommodated in the recess 25. An air chamber 27 is formed above the porous plate 42, and an air suction path 44 formed in the carrier 24 is communicated with the air chamber 27. The air suction path 44 extends outside the holding head 14 as indicated by a two-dot chain line in the drawing. And it is connected to a suction pump (SP) 46. Therefore, when the suction pump 46 is driven, the wafer 50 is sucked into the porous plate 42 and is adsorbed and held on the lower surface of the porous plate 42. The porous plate 42 has a large number of air passages therein, and for example, a porous plate made of a sintered body of a ceramic material is used.
[0010]
The carrier 24 is formed with a large number of air supply passages 48, 48... (Only two are shown in FIG. 2) in which jet ports are formed on the lower surface of the carrier 24. These air supply paths 48, 48... Extend outside the holding head 14 as shown by a two-dot chain line in the figure, and are connected to the pump 40 via a regulator 38C. Therefore, the compressed air from the pump 40 is jetted into the air chamber 51 between the porous plate 42 and the wafer 50 via the air supply passages 48, 48. As a result, a pressure air layer is formed in the air chamber 51, and the pressing force of the carrier 24 is transmitted to the wafer 50 through the pressure air layer. The wafer 50 is pressed against the polishing pad 16 by the pressing force transmitted through the pressure air layer. The air blown out from the air supply paths 48, 48... Is exhausted to the outside through an exhaust hole (not shown) formed in the polishing surface adjustment ring 28.
[0011]
The carrier 24 is formed with a number of air / water supply passages 52, 52... (Only two are shown in FIG. 2) in which jet holes are formed on the lower surface of the carrier 24. These air / water supply paths 52, 52... Extend outside the holding head 14 as shown by a two-dot chain line in the drawing, and are branched in two directions via a valve 54. An air pump 40 is connected to one branch path via a regulator 38D, and a water pump (WP: water pump) 56 is connected to the other branch path. Therefore, when the valve 54 opens the path on the air pump 40 side and the path on the water pump 56 side closes, the compressed air from the air pump 40 enters the air chamber 51 via the air / water supply paths 52, 52. Supplied. When the valve 54 is switched to close the path on the air pump 40 side and open the path on the water pump 56 side, the water from the water pump 56 passes through the air / water supply paths 52, 52. To be supplied.
[0012]
On the other hand, one rubber sheet 30 is disposed between the carrier 24 and the head body 22. The rubber sheet 30 is formed in a disk shape with a uniform thickness. The rubber sheet 30 is fixed to the lower surface of the head body 22 by an annular clasp 58, and is divided into a central portion 30A and an outer peripheral portion 30B with the clasp 58 as a boundary. The central portion 30A of the rubber sheet 30 presses the carrier 24, and the outer peripheral portion 30B presses the polishing surface adjustment ring 28.
[0013]
A space 60 sealed by the central portion 30A of the rubber sheet 30 and the clasp 58 is formed below the head body 22. The air supply path 36 is communicated with the space 60. Therefore, when compressed air is supplied from the air supply path 36 to the space 60, the central portion 30 </ b> A of the rubber sheet 30 is elastically deformed by the air pressure and presses the upper surface of the carrier 24. Thereby, the pressing force of the wafer 50 against the polishing pad 16 can be obtained. Further, if the air pressure is adjusted by the regulator 38B, the pressing force of the wafer 50 can be controlled.
[0014]
The guide ring 26 is formed in a cylindrical shape and is disposed coaxially with the head body 22 at the lower portion of the head body 22. Further, the guide ring 26 is fixed to the head main body 22 via a rubber sheet 30. A cylindrical polishing surface adjustment ring 28 is disposed between the guide ring 26 and the carrier 24. A retainer ring 62 for preventing the wafer 50 from popping out is attached to the lower inner peripheral portion of the polishing surface adjusting ring 28. Further, a stopper groove 28 </ b> A for preventing the polishing surface adjustment ring 28 from falling off is formed on the lower outer peripheral portion of the polishing surface adjustment ring 28. The stopper groove 28 </ b> A engages with a protrusion 26 </ b> A formed on the lower inner peripheral portion of the guide ring 26, thereby preventing the polishing surface adjustment ring 28 from falling off.
[0015]
An annular space 64 that is sealed by the head main body 22 and the outer peripheral portion 30 </ b> B of the rubber sheet 30 is formed in the lower outer peripheral portion of the head main body 22. The air supply path 34 communicates with the space 64. Therefore, when compressed air is supplied from the air supply path 34 to the space 64, the outer peripheral portion 30 </ b> B of the rubber sheet 30 is elastically deformed by air pressure and presses the annular upper surface of the polishing surface adjustment ring 28. As a result, the annular lower surface of the polishing surface adjusting ring 28 is pressed against the polishing pad 16. The pressing force of the polishing surface adjustment ring 28 can be controlled by adjusting the air pressure with the regulator 38A.
[0016]
In FIG. 1, a wafer supply device 70 is disposed adjacent to the polishing surface plate 12 and mainly includes a tray 72, an arm 74, a drive shaft 76, and a motor 78. The tray 72 is formed to a size that can accommodate one semiconductor wafer 50, and a plurality of air jets 80, 80... Are formed on the bottom surface thereof as shown in FIG. These air outlets 80, 80... Communicate with an air supply path 82 formed in the tray 72 and the arm 74, and the air supply path 82 extends outside the wafer supply apparatus 70 and is not shown. It is connected to the air pump through a regulator. Therefore, the compressed air from the air pump is ejected from the air ejection ports 80, 80... Via the air supply path 82. Thereby, the semiconductor wafer 50 accommodated in the tray 72 is supported in a floating state by the air pressure ejected from the air ejection ports 80, 80.
[0017]
The tray 72 is connected to a drive shaft 76 via an arm 74, and the drive shaft 76 is connected to an output shaft (not shown) of the motor 78. Therefore, when the motor 78 is driven, the tray 72 can move along an arc whose radius is the arm 74. The tray 72 has the motor within a range between a position for receiving the semiconductor wafer 50 before polishing from a loading device (not shown) (a position indicated by a solid line in the drawing) and a position for delivering the semiconductor wafer 50 to the holding head 14. It is reciprocated by 78.
[0018]
A wafer carry-out device 90 is arranged in the vicinity of the wafer supply device 70. The wafer carry-out device 90 mainly includes a tray 92, an arm 94, a drive shaft 96, and a motor 98. The tray 92 is formed to a size that can accommodate the polished semiconductor wafer 50, and water 100 is stored in the tray 92 so that the semiconductor wafer 50 is not dried.
[0019]
The tray 92 is connected to a drive shaft 96 via an arm 94, and the drive shaft 96 is connected to an output shaft (not shown) of the motor 98. Therefore, when the motor 98 is driven, the tray 92 can move along an arc whose radius is the arm 94. The tray 92 has a position where the polished semiconductor wafer 50 is delivered from the holding head 14 (a position below the holding head 14) and a position where the semiconductor wafer 50 is delivered to the next process (a position indicated by a solid line in the figure). And reciprocally moved by the motor 98 within the range.
[0020]
Next, the operation of the wafer polishing apparatus 10 configured as described above will be described. First, the semiconductor wafer 50 before polishing is placed in the tray 72 of the wafer supply device 70 waiting at the position indicated by the solid line in FIG. 1 with the polishing surface facing downward. At this time, air is jetted in advance from the air jets 80 of the tray 72. As a result, the semiconductor wafer 50 is immediately supported in a state where the polishing surface is lifted without hitting the bottom surface of the tray 72, so that the polishing surface is not damaged on the bottom surface of the tray 72.
[0021]
Next, the motor 78 of the wafer supply device 70 is driven to move the tray 72 toward the holding head 14, and the holding head 14 is moved up by a lifting device (not shown) to a position away from the polishing pad 16. Position.
Next, as shown in FIG. 4, when the tray 72 is positioned below the holding head 14, air is supplied to the central portion 30A of the rubber sheet 30, and the central portion 30A is expanded with air. Thereby, the carrier 24 is pushed by the central portion 30 </ b> A of the rubber sheet 30, and the porous plate 42 of the carrier 24 protrudes from the lower part of the retainer ring 62. At this time, the carrier 24 moves downward while the lower outer peripheral surface 25 is guided by the inner wall surface 73 of the tray 72. Then, when the carrier 24 is located at a position slightly away from the semiconductor wafer 50, the supply of air is stopped, and the carrier 24 is located at the position shown in FIG. That is, the position of the carrier 24 shown in FIG. 4 is the delivery position of the semiconductor wafer 50.
[0022]
Next, the suction pump 46 (see FIG. 2) on the holding head 14 side is driven to adsorb and hold the non-polished surface of the semiconductor wafer 50 on the porous plate 42. As a result, the semiconductor wafer 50 is held by the holding head 14 from the tray 72. Before the suction pump 46 is driven, air is weakly ejected from the ejection ports of the air supply passages 48, 48... So that external dust (foreign matter) does not enter between the porous plate 42 and the semiconductor wafer 50. Keep it like that.
[0023]
When the semiconductor wafer 50 is held by the holding head 14, the motor 78 of the wafer supply device 70 is driven in the reverse direction so that the empty tray 72 is positioned at the original position shown by the solid line in FIG. 1.
On the other hand, in the holding head 14, the air in the central portion 30 </ b> A in which the rubber sheet 30 is expanded is removed, and the remaining air is sucked by a suction pump (not shown) to move the carrier 24 up and held by the carrier 24. The semiconductor wafer 50 is retracted upward from the lower surface of the retainer ring 62. In addition, since a part of center part 30A of the rubber sheet 30 is bonded to the carrier 24, the carrier 24 moves upward when air in the center part 30A is sucked.
[0024]
Next, as shown in FIG. 5, the holding head 14 is moved downward, and the downward movement is stopped at a position where the lower surface of the retainer ring 62 contacts the polishing pad 16. Then, the suction pump 46 is stopped, the suction of the semiconductor wafer 50 is released, and the wafer 50 is placed on the polishing pad 16.
Next, the pump 40 is driven to supply compressed air to the air chamber 51 through the air supply path 48, and a pressure air layer is formed in the air chamber 51.
[0025]
Then, the compressed air from the pump 40 is supplied to the space 60 through the air supply path 36, the center portion 30A of the rubber sheet 30 is expanded to press the carrier 24, and the wafer 50 is moved through the pressure air layer. Press against the polishing cloth 16. Then, the air pressure is adjusted by the regulator 38B, and the pressing force of the wafer 50 against the polishing pad 16 is kept constant.
[0026]
Next, compressed air from the pump 40 is supplied to the space 64 via the air supply path 34, the outer peripheral portion 30B of the rubber sheet 30 is expanded to press the polishing surface adjustment ring 28, and the polishing surface adjustment ring 28 and the retainer are pressed. The lower surface of the ring 62 is pressed against the polishing pad 16. Then, the air pressure is adjusted by the regulator 38A to keep the pressing force of the polishing surface adjustment ring 28 against the polishing pad 16 constant. Thereafter, polishing of the semiconductor wafer 50 is started by rotating the polishing surface plate 12 and the holding head 14.
[0027]
When the polishing of the semiconductor wafer 50 is completed, the pump 40 is stopped to release the pressure air layer, and the suction pump 46 is driven to hold the non-polished surface of the semiconductor wafer 50 on the porous plate 42. Before driving the suction pump 46, air is weakly ejected from the ejection ports of the air supply passages 48, 48... So that slurry (foreign matter) is not sucked during adsorption.
[0028]
When the semiconductor wafer 50 is sucked and held by the porous plate 42, the holding head 14 is moved up and positioned away from the polishing pad 16. At the same time, the tray 92 of the wafer carry-out device 90 waiting at the position indicated by the solid line in FIG. 1 is moved toward the holding head 14.
Next, as shown in FIG. 6, when the tray 92 is positioned below the holding head 14 (wafer delivery position), the suction pump 46 is stopped, the suction of the semiconductor wafer 50 is released, and the semiconductor wafer 50 is removed from the tray 92. Drop in water 100. Thereafter, the tray 92 is moved to the delivery position for the next process, and the semiconductor wafer 50 is delivered to the next process.
[0029]
The above is the polishing process for one semiconductor wafer 50. When the second and subsequent semiconductor wafers 50 are polished, the above-described steps may be repeated.
Thus, in the present embodiment, the porous plate 42 of the carrier 24 of the holding head 14 is protruded from the retainer ring 62 so that the semiconductor wafer 50 accommodated in the wafer supply device 70 is adsorbed by air. The semiconductor wafer 50 can be automatically held by the holding head 14. Then, after air adsorption by the porous plate 42 is released and the semiconductor wafer 50 is placed on the polishing pad 16, the pressing force from the central portion 30A of the rubber sheet 30 is transmitted to the semiconductor wafer 50 through the pressure air layer. Thus, the semiconductor wafer 50 can be polished efficiently.
[0030]
In this embodiment, a floating type (non-contact type) by air pressure is applied as the wafer supply device 70, but the present invention is not limited to this, and a contact type wafer supply device may be applied. .
Further, in the present embodiment, the wafer supply device 70 and the carry-out device 90 are moved to supply / carry out the semiconductor wafer 50 with respect to the holding head 14. However, the present invention is not limited to this. The semiconductor wafer 50 may be received from the wafer supply device 70 and moved to the wafer carry-out device 90 by moving the 14 side.
[0031]
【The invention's effect】
As described above, according to the wafer holding method of the wafer polishing apparatus according to the present invention, since the carrier suction portion of the holding head protrudes from the retainer ring, the wafer in the wafer storage portion is sucked by air. Can be automatically held by the holding head, and after the air suction by the suction part is released and the wafer is placed on the polishing cloth, the pressing force from the pressing means is transmitted to the wafer via the pressure air layer. However, since the wafer is polished, the wafer can be polished efficiently.
[Brief description of the drawings]
1 is an overall structural view of a semiconductor wafer polishing apparatus according to an embodiment of the present invention. FIG. 2 is a longitudinal sectional view of a holding head of the polishing apparatus shown in FIG. 1. FIG. 3 is a wafer supply shown in FIG. FIG. 4 is a longitudinal sectional view showing a state in which a semiconductor wafer supported by a wafer supply device is being transferred to a holding head. FIG. 5 is a view showing a state in which a semiconductor wafer is sucked and held by a holding head. Longitudinal sectional view [Fig. 6] Longitudinal sectional view showing a state where the polished semiconductor wafer is transferred to the carry-out device [Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Semiconductor wafer polishing apparatus 12 ... Polishing surface plate 14 ... Holding head 16 ... Polishing cloth 24 ... Carrier 28 ... Polishing surface adjustment ring 30 ... Rubber sheet 50 ... Semiconductor wafer 62 ... Retainer ring 70 ... Wafer supply apparatus 90 ... Wafer carry-out apparatus

Claims (2)

Career having a suction portion for air suction of the wafer, the pressure air layer to pressing force from the pressing means to form a pressure air layer between the pressing hand stage, the carrier and the wafer for pressing the carrier to a polishing cloth wafer supply with pressure air layer forming hand stage for transmitting the wafer, and a holding head configured Ritenarin grayed or we surrounding the periphery of the wafer during polishing, a tray wafer before polishing is accommodated through the In a wafer polishing apparatus having a portion and a wafer carry-out portion provided with a tray in which a polished wafer is accommodated ,
After moving the holding head and the wafer supply part in a relatively approaching direction, the suction part of the carrier is protruded from the retainer ring, and the wafer accommodated in the tray of the wafer supply part is moved to the suction part. With air adsorption,
After moving the holding head and the wafer supply unit relatively away from each other, air adsorption by the carrier adsorption unit is released on the polishing cloth, and the wafer is placed on the polishing cloth.
After placing the wafer on the polishing cloth, driving the pressing means and the pressure air layer forming means, polishing the wafer while transmitting the pressing force from the pressing means to the wafer through the pressure air layer,
When the polishing of the wafer is completed, the pressure air layer forming means is stopped, and the polished wafer is air adsorbed by the adsorption part of the carrier,
After moving in the direction toward relatively and said holding head and the wafer unloading section receives the air suction by the suction portion of the carrier wafer to release on the tray of the wafer unloading unit to the tray of the wafer unloading unit A wafer holding method of a wafer polishing apparatus, wherein the wafer is passed. 2. The apparatus according to claim 1, wherein when the wafer is sucked by the carrier suction portion, air is blown out from the periphery of the suction portion so that foreign matters around the carrier are not sucked by the suction portion. Wafer holding method for wafer polishing apparatus.

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