JP2685006B2 - Dry etching equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a dry etching apparatus having an electrostatic attraction stage.

[0002]

2. Description of the Related Art As shown in FIG. 4, an etching apparatus equipped with a typical electrostatic attraction stage has a cassette stage 9 on which a cassette 8 containing a wafer 7 is placed and a wafer 7 taken out from the cassette 8. It has a transfer chamber 11 in which a transfer robot 10 is installed for transfer, and a processing chamber 12 for performing etching by plasma processing. Then, in order to carry the wafer 7 into the processing chamber 12, the cassette 8 placed on the cassette stage 9 by the transfer robot 10 is loaded.
The wafer 7 is taken out from the inside, the wafer 7 is once loaded into the transfer chamber 11, and the transfer chamber 11 is evacuated to a vacuum state. Then, the gate valve 15 is opened to separate the transfer chamber 11 and the processing chamber 12. The wafer 7 is transferred to the inside of the processing chamber 12 by the transfer robot 10.

FIG. 5 is a sectional view showing a processing chamber 12 equipped with a conventional electrostatic attraction stage 4. FIG. 4A is a sectional view showing an etching process, and FIG. 4B is a sectional view showing a state where the wafer is pushed up from the electrostatic adsorption stage. In the processing chamber 12, a pair of upper electrode 1 and lower electrode 3 for applying high frequency power, a gas inlet 2a for supplying gas into the upper electrode 1, and an exhaust port 2b for exhausting the inside of the processing chamber 12 are provided. An electrostatic attraction stage 4 installed on the lower electrode 3, a cover ring 13, and lift pins 5 for moving the wafer 7 up and down are provided.

The back surface of the wafer 7 transferred into the processing chamber 12 by the transfer robot shown in FIG. 4 is supported by the lift pins 5, and when the lift pins 5 descend and sink into the electrostatic adsorption stage 4, the wafer 7 is removed. Is the electrostatic adsorption stage 4
Placed on top. The processing chamber 12 is kept at a certain constant pressure within a range of several hundred mTorr to several tens Torr while the gas from the gas inlet 1 is flown from the gas inlet 14 of the upper electrode 1, and the high frequency of 13.56 MHz is used. Power the upper electrode 1
Is applied between the lower electrode 3 and the lower electrode 3 to generate plasma, and the wafer 7 on the electrostatic adsorption stage 4 is etched by the plasma.

When a positive or negative DC voltage is applied to the electrostatic attraction stage 4 during plasma generation, the wafer 7 is attracted to the electrostatic attraction stage 4 by electrostatic force, and the wafer is heated by the heating means (not shown) of the electrostatic attraction stage 4. Are heated uniformly. After the etching process is completed, lift pins 5 provided in the electrostatic attraction stage 4 support the back surface of the wafer 7 and push the wafer 7 upward. The wafer 7 pushed up by the lift pins 5 is carried out of the processing chamber 12 by the transfer robot shown in FIG. 4 and replaced with a new wafer 7.

[0006]

In a dry etching apparatus equipped with an electrostatic adsorption stage, when the wafer is pushed up and separated from the electrostatic adsorption stage after the etching process is completed, residual charges remain on the wafer and the wafer is electrostatically adsorbed on the electrostatic adsorption stage. Phenomenon that does not leave. Therefore, in the conventional dry etching apparatus, the residual charge is released from the lift pins 5 that push up the wafer 7,
Prevents the electric charge from remaining on the wafer 7,
Is easily separated from the electrostatic adsorption stage 4.

However, in the case where an insulating film or the like is attached to the back surface of the wafer 7 and electrical continuity with the lift pins 5 cannot be obtained,
In some cases, residual charges may remain on the wafer 7, and in this case,
When the wafer 7 is forcibly separated from the electrostatic adsorption stage 4 by the lift pins 5, the wafer 7 jumps up,
The wafer 7 may be laterally displaced and supported on the lift pins 5.

When the wafer 7 is transferred with the wafer 7 being displaced and supported on the lift pins 5, the transfer robot shown in FIG. Or
Also, the wafer cannot be detected by the sensor of the transfer robot and the operation of the dry etching equipment is stopped because a failure occurs, or the wafer is supported in a slanted and tilted state and collides with the transfer robot and a wafer crack occurs. Trouble occurs.

As another method for releasing the residual charge, a method is conceivable in which plasma is generated by an inert gas or the like after the etching process to release the residual charge on the wafer and the wafer is easily separated from the electrostatic adsorption stage. After the etching process is completed, the etched surface of the wafer is exposed again to the plasma, and the processed surface of the wafer is abnormally etched.

An object of the present invention is to provide a dry etching apparatus which can separate a wafer having a residual charge from the electrostatic attraction stage without displacement.

[0011]

In order to achieve the above object, a dry etching apparatus according to the present invention has an electrostatic adsorption stage, a lift section, and a wafer guide, and one of a pair of processing chambers is provided. A dry etching apparatus that applies a high-frequency power between a pair of electrodes while introducing gas from the electrodes to generate plasma, and performs an etching process on a wafer by the plasma, wherein the electrostatic adsorption stage is the other electrode of the pair. Is provided on the side to hold the wafer by electrostatic force by applying a DC voltage, and the lift portion is provided so as to be able to move up and down, and is provided between the electrostatic attraction stage and the wafer loading / unloading position above it. Support the back surface of the wafer and move up and down to place the wafer on the electrostatic adsorption stage, or remove the wafer from the electrostatic adsorption stage and push it to the wafer loading / unloading position. Is intended to increase, the wafer guide is disposed strategically wafer periphery on the electrostatic suction stage, wafer periphery strategic points to guide the wafer
Operating position and standby position separated from the wafer
It moves and guides the peripheral edge of the wafer pushed up by the lift portion.

[0012]

[0013]

Further, the wafer guide stands by on the side of the electrostatic attraction stage.

Further, the wafer guide stands by on the side of the one electrode for introducing gas.

Further, the wafer guide has a guide pin, and the guide pin is arranged at a peripheral portion of the wafer on the electrostatic attraction stage.

Further, the wafer guide has a mold, and the mold is shaped according to the outer shape of the wafer and is arranged at a peripheral portion of the wafer on the electrostatic attraction stage.

[0018]

[Function] When the wafer guide is placed at the peripheral position of the wafer on the electrostatic attraction stage and the wafer is pushed up from the electrostatic attraction stage by the lift pins, the height of the wafer guide from the vicinity of the electrostatic attraction stage to the vicinity of the wafer loading / unloading position. It is provided upright to the position, and the peripheral edge of the wafer is guided by the rising portion of the wafer guide to correct the lateral displacement of the wafer on the lift pins.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a sectional view showing a processing chamber of a dry etching apparatus according to Embodiment 1 of the present invention.

In the figure, inside the processing chamber 12, a pair of upper electrode 1 and lower electrode 3 for applying high frequency power, a gas inlet 2a for supplying gas into the upper electrode 1, and the inside of the processing chamber 12 are shown. An exhaust port 2b for exhausting, an electrostatic adsorption stage 4 installed on the lower electrode 3, a cover ring 13, and a lift pin 5 for raising and lowering the wafer 7 are provided.
The electrostatic attraction stage 4 attracts and holds the wafer 7 by electrostatic force. Wafer 7 on electrostatic chuck stage 4
The principle that is absorbed by electrostatic force is explained as follows. That is, a positive or negative DC voltage is applied to the electrostatic adsorption stage 4 during the period in which plasma is generated in the processing chamber 12, thereby providing a potential difference between the stage 4 and the wafer 7 via the plasma. As a result, electrostatic force is generated, and the electrostatic force causes the wafer 7 to move to the stage 4
Is adsorbed on. This technique is general purpose. A lift pin 5, which forms a lift portion, is incorporated in the electrostatic adsorption stage 4 so as to be able to move up and down. Then, the wafer 7 is placed on the electrostatic adsorption stage 4, or the wafer 7 is detached from the electrostatic adsorption stage 4 and pushed up to the wafer loading / unloading position A (see FIG. 1C). The lift pins 5 are transferred at the wafer loading / unloading position A by the transfer robot 10 shown in FIG.

Further, the present invention has the wafer guide 6 in the processing chamber 12. The wafer guide 6 is arranged at a peripheral portion of the wafer on the electrostatic adsorption stage 4 and guides the peripheral edge of the wafer 7 to be pushed up by the lift pins 5. More specifically, the wafer guide 6 is located near the electrostatic adsorption stage 4 at the wafer loading / unloading position. It has a rising portion 6a that rises to a height position B near A (see FIG. 1B), and the rising portion 6a guides the peripheral edge of the wafer 7.

Further, the wafer guide 6 guides the peripheral edge of the wafer 7, and the operating position C (see FIG.
(See (b)) and the standby position D separated from the wafer 7.
(See FIG. 1 (a)). The wafer guide 6 according to the first embodiment of the present invention stands by on the side of the electrostatic attraction stage 4 and moves from the standby position D to the peripheral position of the wafer 7 at an operation position C at a peripheral position of the wafer.
It is a movable structure that moves to.

A specific example of the wafer guide 6 according to the first embodiment of the present invention will be described below with reference to FIG. As shown in the figure, the lower electrode 3, the electrostatic adsorption stage 4, the cover ring 13
Is provided with a through hole 16 penetrating vertically corresponding to the outer peripheral edge of the wafer 7 on the electrostatic attraction stage 4, and the wafer guide 6 is incorporated in the through hole 16 so as to be able to move up and down. The wafer guide 6 has the rising portion 6 at the upper end thereof.
a is provided, and its lower end is connected to an elevator (not shown).

The wafer guide 6 of the embodiment shown in FIG. 2A has at least three guide pins 17. In this case, at least four or more through-holes 16 are provided in the peripheral portion of the wafer on the electrostatic attraction stage 4, and the guide pins 17 of the wafer guide 6 are provided in the through-holes 1.
Each guide pin 17 is provided in the inside of the guide 6 so as to be able to move up and down. The guide pin 17 is provided with the rising portion 6a at its upper end, and its lower end is connected to an elevator (not shown). The guide pin 17 is
Since the orientation flats 7a are formed on a part of the wafer 7, four pieces are provided. However, in the case of a circular wafer without the orientation flats 7a, at least three pieces may be provided, and the important point is not to rotate the wafer 7. The number is not limited as long as it is a number that can prevent lateral displacement.

The wafer guide 6 of the embodiment shown in FIG. 2B has a form (shaded portion) 18, and the form 18 is shaped according to the outer shape of the wafer 7, The rising portion 6a is arranged on the electrostatic attraction stage 4 at a peripheral portion of the wafer, and the rising portion 6a is provided on the inner peripheral side of the mold 18. In this case, the through hole 16 is provided so as to surround the wafer peripheral edge in a ring shape. The mold 18 has a ring shape surrounding the entire periphery of the wafer, but a mold divided into a plurality of parts in the circumferential direction may be used, and the mold forming a part of the circumference may be used. 18 may be arranged in the circumferential direction with an empty space having a predetermined pitch.

Next, the operation will be described. The back surface of the wafer 7 transferred into the processing chamber 12 is supported by the lift pins 5, and is placed on the electrostatic adsorption stage 4 as the lift pins 5 descend. The processing chamber 12 has a gas inlet 1
Several hundred mT with the gas from the gas flowing from the gas inlet 14
The plasma is generated by applying a high frequency power of 13.56 MHz between the lower electrode 3 and the upper electrode 1 while maintaining a certain constant pressure within the range of orr to several tens Torr, and the plasma is generated on the electrostatic adsorption stage 4. The wafer 7 is etched. When a positive or negative DC voltage is applied to the electrostatic attraction stage 4 during plasma generation, the wafer 7 is attracted to the electrostatic attraction stage 4 by electrostatic force.

FIG. 1A is a sectional view showing the processing chamber during the etching process. After the etching process is completed, before the wafer 7 is lifted by the lift pins 5, the wafer guide 6 moves up to the outer peripheral portion of the wafer 7, and the wafer guide 6 moves from the vicinity of the electrostatic attraction stage 4 to the height position B near the wafer loading / unloading position A. The rising portion 6a is positioned so as to guide the peripheral edge of the wafer 7 (see FIG. 1B).

In FIG. 1B, the wafer 7 is lifted by a lift pin 5.
It is sectional drawing of the process chamber 12 just before raising by. The clearance between the peripheral edge of the wafer 7 and the rising portion 6a of the wafer guide 6 is preferably about 1 mm in consideration of the accuracy of transporting the wafer 7. Next, the wafer 7 is pushed up by the lift pins 5 provided in the electrostatic adsorption stage 4 and separated from the electrostatic adsorption stage 4. At this time, the wafer 7 bounces off due to the residual charge, but the peripheral edge of the wafer 7 is restrained by the wafer guide 6 and the wafer 7 on the lift pins 5 is restrained.
It is possible to suppress the lateral shift of about 1 mm. The deviation of about 1 mm can be corrected by making the shape of the wafer loading position of the transfer robot 10 into a generally tapered drop shape. FIG. 1 (c)
FIG. 4 is a sectional view of the processing chamber 12 in which a wafer is lifted up to a wafer loading / unloading position A. The wafer 7 pushed up to the wafer loading / unloading position A by the lift pins 5 is replaced by the transfer robot 10 provided in the transfer chamber 11.

(Embodiment 2) FIG. 3 is a sectional view showing a processing chamber of a dry etching apparatus according to Embodiment 2 of the present invention.

In the case of the first embodiment, the through holes 16 are provided on the cover ring 13 at the peripheral edge of the wafer, and when the wafer 7 is etched, the through holes 16 cause a non-uniform plasma state during the etching process. Sometimes becomes.

Therefore, in the second embodiment of the present invention, the wafer guide 6 is made to stand by on the upper electrode 1 side. In the second embodiment, the through hole 16 is provided in the lower surface of the upper electrode 1, the wafer guide 6 is incorporated in the through hole 16, and when the wafer 7 is pushed up by the lift pin 5, the wafer guide 6 is extended downward from the through hole 16. The peripheral edge of the wafer 7 is guided.

The wafer guide 6 of the second embodiment is provided at its lower end with a rising portion 6a which rises from the vicinity of the electrostatic attraction stage 4 to the height position B near the wafer loading / unloading position A (see FIG. 3B). Its upper end is connected to an elevator (not shown). As the wafer guide 6 of the second embodiment, as shown in FIG.
A wafer guide having the guide pins 17 of the embodiment shown in (a) or a wafer guide having the mold frame 18 of the embodiment shown in FIG. 3 (b) can be used.

FIG. 3A shows the processing chamber 1 during the etching process.
2 is a sectional view of FIG. The wafer guide 6 is accommodated inside the upper electrode 1 during the etching process.
Before the wafer 7 is lifted by the lift pins 5 after the etching process, the wafer guide 6 is lowered to the outer peripheral portion of the wafer 7, and its rising portion 6a is located at a height position B near the wafer loading / unloading position A near the electrostatic attraction stage 4. Since the wafer 7 is placed upright and guides the peripheral edge of the wafer 7, it serves to prevent the wafer 7 from laterally shifting on the lift pins 5 when the wafer is detached.

FIG. 3B is a sectional view of the processing chamber 12 immediately before the wafer 7 is lifted by the lift pins 5. The gap between the peripheral edge of the wafer 7 and the rising portion 6a of the wafer guide 6 is preferably about 1 mm considering the accuracy of transportation.

FIG. 3C is a sectional view of the processing chamber 12 when the wafer 7 is lifted up to the wafer loading / unloading position A and the wafer guide 6 is lifted up to the gas introduction part. After the wafer 7 is lifted up, the wafer guide 6 is moved up into the upper electrode 1, and then the transfer robot 10 provided in the processing chamber 12 replaces the wafer 7 on the lift pins 5. In this embodiment, the wafer guide 6 is the upper electrode 1.
Since the wafer 7 is placed inside, the wafer 7 on the electrostatic attraction stage 4 does not have holes such as the through holes 16 as in the first embodiment, and the plasma state becomes non-uniform during the etching process. Does not affect. Further, the structures of the electrostatic attraction stage 4 and the lower electrode 3 are simplified, and the manufacture and maintenance are easy.

[0037]

As described above, according to the present invention, the wafer guide is disposed on the electrostatic chuck stage at the peripheral portion of the wafer on the electrostatic chuck stage, and when the wafer is pushed up from the electrostatic chuck stage by the lift pins, the wafer guide is not moved. It is installed upright from the vicinity of the electro-adsorption stage to a height near the wafer loading / unloading position, and since the rising edge of the wafer guide guides the peripheral edge of the wafer, the lateral displacement of the wafer on the lift pins when the wafer is removed. Can be corrected, and a wafer transfer error and a wafer crack can be prevented.

Further, since the wafer guide is moved to the operation position of the peripheral portion of the wafer for guiding the wafer and the standby position separated from the wafer, it is possible that the wafer guide adversely affects the plasma state during the etching process. It can be avoided.

Further, the wafer guide can be made to stand by either on the side of the electrostatic attraction stage or on the side of the electrode for introducing gas, so that the degree of freedom in dry etching design can be increased.

Further, by making the wafer guide stand by on the electrode side of gas introduction, there is no interfering substance that adversely affects the plasma state during the etching process at the wafer periphery,
The plasma state can be kept uniform.

Further, a guide pin or a mold can be selected and used for the wafer guide.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a structure of an etching processing chamber of a dry etching apparatus according to a first embodiment of the present invention, in which (a) is an etching process and (b) is a wafer lift-up process.
(C) is a cross-sectional view showing the processing chamber after the wafer is lifted up.

FIG. 2A is a plan view showing an embodiment in which the wafer guide of the present invention has a guide pin, and FIG. 2B is a plan view showing an embodiment in which the wafer guide of the present invention has a mold.

3A and 3B are cross-sectional views showing the structure of an etching processing chamber of a dry etching apparatus according to a second embodiment of the present invention, where FIG. 3A is during etching processing, and FIG.
(C) is a cross-sectional view showing the processing chamber after the wafer is lifted up.

FIG. 4 is an overall view showing a dry etching apparatus.

5A and 5B are cross-sectional views showing a structure of an etching processing chamber of a conventional dry etching apparatus, wherein FIG. 5A is a sectional view showing an etching process and FIG. 5B is a sectional view showing a processing chamber after a wafer is lifted up.

[Explanation of symbols]

 1 Upper Electrode 2a Gas Inlet 2b Exhaust 3 Lower Electrode 4 Electrostatic Adsorption Stage 5 Lift Pin 6 Wafer Guide 6a Rise 7 Wafer 8 Cassette 9 Cassette Stage 10 Transfer Robot 11 Transfer Chamber 12 Processing Chamber 13 Covering 14 Gas Inlet 15 Gate valve

Claims (5)

(57) [Claims] 1. An electrostatic adsorption stage, a lift section, and a wafer guide are provided, and high-frequency power is applied between the pair of electrodes while introducing gas from one of the paired electrodes in the processing chamber to generate plasma. A dry etching apparatus for generating and etching a wafer with the plasma, wherein an electrostatic adsorption stage is provided on the other electrode side of the pair and adsorbs and holds the wafer with electrostatic force by applying a DC voltage. The lift unit is provided so as to be able to move up and down, and supports the back surface of the wafer between the electrostatic adsorption stage and the wafer loading / unloading position above it to move up and down to place the wafer on the electrostatic adsorption stage. Alternatively, the wafer is detached from the electrostatic adsorption stage and pushed up to the wafer loading / unloading position, and the wafer guide is the wafer edge on the electrostatic adsorption stage. Wafers that are placed at key points and guide the wafers
Operating position of peripheral points and standby separated from the wafer
A dry etching apparatus which moves to a position and guides a peripheral edge of a wafer pushed up by the lift portion. 2. The wafer guide stands by at the side of the electrostatic attraction stage.
1. The dry etching apparatus according to 1. 3. The dry etching apparatus according to claim 1 , wherein the wafer guide stands by on the side of the one electrode for introducing gas. Wherein said wafer guide has a guide pin, guide pin according to claim 1, 2 or 3, characterized in that arranged in the wafer periphery strategic points on the electrostatic suction stage The dry etching apparatus according to 1. 5. The wafer guide has a mold, and the mold is shaped according to the outer shape of the wafer and is arranged at a peripheral portion of the wafer on the electrostatic attraction stage. The dry etching apparatus according to claim 1, 2, or 3 .