JPH07201829A - Method of cleaning plasma processor - Google Patents

Abstract

PURPOSE:To provide a method of cleaning a plasma processor whereby the executing time of the cleaning of a member present in the processing chamber of the plasma processor can be set clearly and accordingly, the depositing of particles on an object to be processed is suppressed and as a result, the yield of the objects to be processed can be improved. CONSTITUTION:In a plasma processor 1, the application of a high-frequency power is performed in a reduced pressure atmosphere, and a plasma is generated, and thereby, an object (W) to be processed is processed. In a method of cleaning this plasma processor, a process for integrating the application time of the high-frequency power, a process for outputting an indicating signal 41, and a process for cleaning a member 18 thereafter are provided respectively. That is, after the integrated value of the application time exceeds a predetermined value, by the outputting of the indicating signal 41, the member 18 present in a processing chamber 2 for processing the object W to be processed is cleaned.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cleaning method for a plasma processing apparatus.

[0002]

2. Description of the Related Art Conventionally, a plasma processing apparatus, for example, a plasma etching apparatus is known as a processing apparatus for converting a gas into plasma and processing an object in a semiconductor manufacturing process. In such a plasma etching apparatus, in order to perform highly reproducible processing, it is necessary to properly mount a semiconductor wafer on a predetermined portion of a target object holding portion, for example, a lower electrode as a mounting table. Therefore, as one of the members provided in the processing chamber, a ring-shaped pressing mechanism that presses and holds the outer peripheral edge of the semiconductor wafer from the upper portion to the lower electrode is provided. As shown in FIG. 5A, the pressing mechanism has a pressing surface 101 formed on the side of the clamp ring 100 that presses the semiconductor wafer W. The semiconductor wafer W is configured to be guided and positioned at a predetermined position on the lower electrode 102.

[0003]

However, in the vicinity of the tapered surface of the above-mentioned conventional clamp ring, the reaction product 103 generated by plasma is attached as shown in FIG. When such a reaction product 103 grows up to the pressing surface 101 of the clamp ring 100, when the outer peripheral edge of the semiconductor wafer W is pressed by the pressing surface 101 of the clamp ring 100, as shown in FIG. When the reaction product 103 in the vicinity of the pressing surface 101 of the clamp ring 100 comes into contact with the semiconductor wafer W, the reaction product 103 is peeled or damaged, and the separated product is scattered as particles and scattered. There is a problem that the reaction product 103a adheres to the semiconductor wafer W. Therefore, conventionally, maintenance is performed by artificially managing, for example, cleaning the members provided in the processing chamber once a week. However, the maintenance time cannot be set clearly, and if the cleaning time is wrong, there is a problem that reaction products adhere to the semiconductor wafer.

If the reaction product adheres to the semiconductor wafer in this way, it causes defects in integrated circuits and the like formed on the semiconductor wafer, leading to a reduction in yield. There has been a demand for development of a cleaning method for a plasma processing apparatus, which makes it possible to clearly set the timing of carrying out the cleaning step for cleaning the attached reaction products.

An object of the present invention is to be able to clearly set the timing for carrying out the step of cleaning the members in the processing chamber of the plasma processing apparatus, thereby suppressing the adhesion of particles to the object to be processed and improving the yield of the object to be processed. It is an object of the present invention to provide a cleaning method of a plasma processing apparatus capable of performing the cleaning.

[0006]

According to a first aspect of the present invention, there is provided a method for cleaning a plasma processing apparatus, wherein a high frequency power is applied in a reduced pressure atmosphere to generate a plasma, thereby treating the object to be processed. A step of integrating the application time, a step of outputting an instruction signal for cleaning a member in the processing chamber for processing the object to be processed after the integrated time exceeds a predetermined time, and after this step, the member is And a step of washing. The invention of claim 2 is
In a cleaning method of a plasma processing apparatus for applying a high-frequency power in a reduced pressure atmosphere to generate a plasma, a method for cleaning a plasma processing apparatus, a step of integrating the application time of the high-frequency power, and the integration time is a predetermined time or more. After that, a step of outputting an instruction signal for cleaning the member in the processing chamber for processing the object to be processed and stopping the application of the high frequency power, and a step of cleaning the member based on the instruction signal It is characterized by having done. The invention of claim 3 is
In a cleaning method of a plasma processing apparatus for applying a high-frequency power in a reduced pressure atmosphere to generate a plasma, a method for cleaning a plasma processing apparatus, a step of integrating the application time of the high-frequency power, and the integration time is a predetermined time or more. After that, a step of outputting an instruction signal for cleaning the member in the processing chamber that processes the object to be processed, and if the object to be processed is being processed, or after the object is processed or before or after the object is processed. In this case, the method further comprises: stopping the application of the high-frequency power after outputting the instruction signal, and cleaning the member based on the instruction signal. The invention according to claim 4 is characterized in that the cleaning of the member is carried out by cleaning with a cleaning agent after polishing with a polishing member having a hardness substantially the same as the hardness of the member. The invention of claim 5 is characterized in that the member is a clamp ring for holding an object to be processed. The invention of claim 6 is characterized in that the integrated time is set to a predetermined time within 100 hours. The invention according to claim 7 is characterized in that the integrated time is set to a time of a member provided in the processing chamber for which a cleaning step is performed for the shortest time.

[0007]

According to the present invention, it is possible to clearly set the execution time of the cleaning process of the member in the processing chamber based on the integrated time of the application time of the high frequency power in the plasma processing apparatus, to properly clean the member and attach it to the member. It is possible to prevent the deposits from becoming particles and adhering to the object to be processed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a plasma etching apparatus will be described below with reference to the accompanying drawings.

First, as shown in FIG. 1, a plasma etching apparatus 1 has a substantially cylindrical airtight processing chamber 2 made of a conductive material such as aluminum. An elevating mechanism, for example, a servo motor 3 is provided in the lower portion of the processing chamber 2, and a lower electrode 4 as a mounting table configured to be vertically movable by the servo motor 3 is provided inside the processing chamber 2. ing. A bellows 5 made of a material such as stainless steel is provided around the lower electrode 4 so that the bellows 5 can expand and contract as the lower electrode 4 moves up and down and airtightly isolates the inside of the processing chamber 2. There is.

The lower electrode 4 is provided with a coolant containing portion, for example, a cooling jacket 6 for circulating and circulating a coolant, for example, a chiller, and the cooling jacket 6 is provided with a coolant supply for supplying and discharging the chiller. / The discharge path 7 is connected. Further, the lower electrode 4 is provided with a temperature adjustment heater 8, and the temperature adjustment heater 8 is connected to a power source 10 for supplying power to the temperature adjustment heater 8 via a power supply lead wire 9. The lower electrode 4 can be set to a predetermined temperature, for example, 20 ° C. or lower, by the temperature adjusting heater 8 and the refrigerant contained in the refrigerant jacket 6.

Further, the lower electrode 4 is made of a conductive material whose surface is anodized, such as aluminum, and an insulating material such as Kapton tape 11 is attached to the surface on which the object to be processed such as the semiconductor wafer W is placed. The semiconductor wafer W is mounted on the upper surface of the Kapton tape 11. Then, the lower electrode 4 is provided with a plurality of, for example, three through-holes 12, and the through-holes 12 are provided with lifter pins 13, respectively, and these lifter pins 13 are connected via a joining member 14. It is connected to an up-and-down mechanism, for example, an air cylinder 15, and is vertically movable. The semiconductor wafer W is supported by the lifter pins 13 and is configured to be attached to and detached from the mounting surface of the lower electrode 4 by vertically moving the air cylinder 15.

Exhaust means, such as a vacuum pump 17, is connected near the lower side of the processing chamber 2 through an exhaust pipe 16 so that the processing chamber 2 can be evacuated to a desired reduced pressure atmosphere. Is configured.

A ring-shaped material made of, for example, aluminum whose surface is alumite-treated is formed on the upper portion of the lower electrode 4 to press the outer peripheral edge portion of the semiconductor wafer W placed on the lower electrode 4. A pressing mechanism for holding, for example, a clamp ring 18 is provided. The clamp ring 18 is connected to an air cylinder 20 provided on the outer upper side of the processing chamber 2 through a plurality of, for example, four shafts 19 made of high-purity alumina.
The position of the clamp ring 18 can be adjusted, and the pressing force of the clamp ring 18 acts evenly on the wafer W surface.

The semiconductor wafer W is provided on the surface of the clamp ring 18 facing the semiconductor wafer W, that is, on the inner side.
In order to guide and position the sheet, a tapered surface 21 is formed as shown in an enlarged view in FIG. The angle of the tapered surface 21 has a function of aligning with the predetermined position of the lower electrode 4 when the semiconductor wafer W is clamped, and the angle of the tapered surface 21 may be any number as long as this function is achieved. Then, inside the tapered surface 21, in order to press the semiconductor wafer W against the lower electrode 4, upward (toward the upper electrode direction toward the inner peripheral side) α degrees, for example, 0.1 degrees to 2. It has a predetermined angle in the range of 0 degree, preferably about 0.9 degree and has a width of, for example, 0.5 m.
Distance in the range of m-2.5 mm, preferably about 1.5 mm
The semiconductor wafer W having the width 11 of the lower electrode 4
A pressing surface 22 that presses and holds it at a predetermined position is formed. Then, on the inner peripheral side of the pressing surface 22, a ridge portion for preventing reaction products generated by plasma from advancing to the pressing surface 22 side and adhering, for example, downward (toward the inner peripheral side). Therefore, it has a predetermined angle of β degrees, for example, 1.0 degree or more, preferably about 3.0 degrees in the direction of the lower electrode), and has a width in the range of 0.5 mm to 2.5 mm, preferably about A notch 23 having a width 12 of 1.0 mm is formed.

An upper electrode 24 facing the lower electrode 4 is provided on the upper part of the clamp ring 18. The lower surface of the upper electrode 24 has a conductive plate-like member 2 made of a material such as amorphous carbon.
5 is provided, and a void 26 is opened above it. A reaction gas such as CHF ₃ ,
A gas supply pipe 27 for supplying a gas such as CF ₄ or an inert gas, for example, a gas such as N ₂ or Ar is connected,
The gas supplied from the gas supply pipe 27 is supplied to the space 2
The gas is evenly diffused by a plurality of baffle plates 28 having a large number of through holes provided in 6 and is supplied into the processing chamber 2 through a plurality of through holes 29 provided in the plate member 25. It is configured.

A high frequency wave, for example, 13.56, is applied to the upper electrode 24 through the blocking capacitor 30.
A high frequency power source 31 such as MHz or 40 MHz is connected, and the lower electrode 4 is electrically grounded. Further, the high frequency power supply 31 is turned on / off according to an instruction from the controller 32.
The controller 32 is configured to perform FF, and is configured to integrate the ON time of the high frequency power supply 31, that is, the application time of the high frequency power. Furthermore, this controller 3
2 has a keyboard 42 of the control panel 40 in advance.
From the above, a pressing mechanism as one member in the processing chamber 2,
For example, the execution timing of the cleaning process for cleaning the clamp ring 18 is set. Then, when the integrated time of application of the high-frequency power becomes longer than the set execution time of the cleaning step, the controller 32 instructs the control panel 40 to clean the member, and the like.
1, the control panel 40
The display 43 is configured to display.

Next, the operation of the plasma etching apparatus 1 configured as described above will be described.

First, as shown in FIG. 1, the internal pressure of the processing chamber 2 is set to a predetermined pressure by the vacuum pump 17, for example, 10-3 Torr.
In the following reduced pressure atmosphere, the semiconductor wafer W is supported by the lifter pins 13, and the lifter pins 13 are moved downward by the air cylinder 15 to be mounted on the semiconductor wafer mounting surface of the lower electrode 4.

After that, the lower electrode 4 is lifted by the lifting mechanism 3, and the peripheral edge of the semiconductor wafer W is clamped by the clamp ring 1.
The semiconductor wafer W is fixed on the lower electrode 4 by being brought into contact with the lower electrode 4. At this time, as the lower electrode 4 rises, the peripheral edge of the semiconductor wafer W first contacts the tapered surface 21 of the clamp ring 18 and is guided by the tapered surface 21 as shown in FIG. 4 is moved to a predetermined position and fixed.

Thereafter, as shown in FIG. 1, the inside of the processing chamber 2 is evacuated and a predetermined vacuum degree, for example, several tens of mTorr is set, and a predetermined gas is supplied from the gas supply pipe 27, and the controller 32 is operated. The high frequency power supply 31 is turned on by the instruction signal of
A high frequency power, for example, a power of 200 KW or more is applied between the lower electrode 4 and the upper electrode 24 to generate plasma, and the semiconductor wafer W is etched.

As shown in FIG. 2, the reaction product 35 generated by plasma by this etching process adheres to the upper part of the clamp ring 18 and the vicinity of the ridge 23. In this way, the reaction product 35 remains attached,
When the semiconductor wafers W are continuously fixed by the cram ring 18, as shown in FIG. 3, the amount of particles of 0.2 μm or more due to the reaction product 35 attached within 5 mm from the outer peripheral edge portion of the semiconductor wafer W is substantially It gradually increases up to 80 hours or more, but does not increase rapidly, and is approximately 10
It will increase from the time when the high frequency power is applied for 0 hours or more. Therefore, it is desirable to clean the members in the processing chamber 2 within a time not exceeding about 100 hours, and it is particularly preferable to clean the members within 80 hours. In addition, since the yield of the integrated circuits formed on the semiconductor wafer W is reduced when the adhesion of the particles is increased, the cleaning process of the clamp ring 18 is performed depending on the application time of the high frequency power accumulated in the controller 32. You can set the time.

Next, the operation of the controller 32, the control panel 40 and the high frequency power source 31 of the plasma etching apparatus 1 and the method of cleaning the members will be described.

As shown in FIG. 4, the control panel 4
The controller 32 sets the cleaning time to a time when the amount of particles of 0.2 μm or more due to the above-described reaction product 35 starts to influence the influence of the yield on the semiconductor wafer W from the keyboard 42 of 0, for example, 80 hours. (Step 70 in FIG. 4)

After that, the controller 32 turns on the high frequency power source 31 according to a predetermined processing of the semiconductor wafer W.
Alternatively, it is turned OFF, but only the ON time is integrated, and the integrated time is compared with the above-mentioned cleaning time. (Fig. 4
Medium 71 process)

According to this comparison, when the integrated time of high frequency (RF) application is shorter than the cleaning time, the high frequency power supply 31 is normally turned on or off without interlocking so as not to be turned on, and the semiconductor wafer is turned on. Process W and feed back before step 71. (Step 72 in FIG. 4)

In step 71, if the integrated time of the high frequency (RF) application is longer than the cleaning time, it is determined whether the semiconductor wafer W is being processed. (73 in FIG. 4
Step 7) If the semiconductor wafer W is being processed, feedback is given before Step 71. In addition, the semiconductor wafer W
When the semiconductor wafer W is not being processed, that is, before or after the processing of the semiconductor wafer W, an instruction signal 41 from the controller 32 is displayed on the display 43 of the control panel 40 such that the members in the processing chamber 2 are cleaned. Instruct them to do it. Also,
Interlock the high frequency power supply so that it will not turn on. (Step 74 in FIG. 4) When the semiconductor wafer W is being processed in the step 74, the reason why the high frequency power supply is not interlocked is that the semiconductor wafer W being processed is stopped during the processing. This is to prevent the semiconductor wafer W from being defective.

After step 74, the control panel 40
The operator cleans the members in the processing chamber 2 based on the instruction displayed on the display 43. (Step 75 in FIG. 4)

In order to prevent the clamp ring 18 from being polished, as shown in FIG. 5, the method for cleaning this member is such that the clamp ring 18 is attached to the clamp ring 18 with a polishing member 80 having substantially the same hardness as the clamp ring 18. After polishing the attached reaction product 35, the clamp ring 18 is washed with a cleaning agent such as alcohol.

Next, as shown in FIG. 4, after the above-described step 75, the keyboard 42 of the control panel 40 initializes the integrated time of the application of the high frequency power to the controller 32 and the high frequency power supply. The interlock for 31 is released. (Step 76 in FIG. 4)

After the step 76, if the cleaning time is to be changed, the process proceeds to step 70, and if the cleaning time is not to be changed, the process proceeds to step 71.
(Step 77 in FIG. 4)

The effects of this embodiment having the above-described structure will be described.

Based on the integrated time of the application time of the high frequency power, it is possible to clearly set the execution time of the cleaning process of the members in the processing chamber, the members can be properly cleaned, and the deposits attached to the members become particles. Adhesion to the wafer W can be suppressed, and the yield of the semiconductor wafer W can be improved.

Further, when the semiconductor wafers W are processed by a plurality of devices, the cleaning time of the parts can be set and clarified for each device, and the yield of the semiconductor wafers W can be made uniform due to the difference between the devices.

In the embodiment, the case where the semiconductor wafer is used as the object to be processed has been described, but the present invention is not limited to this.
For example, an LCD substrate may be used, and an example of a clamp ring has been described as a member in the processing chamber. However, any member provided in the processing chamber to which the reaction product adheres may of course be any member. Is. Furthermore, in the examples, an example in which the processing apparatus according to the present invention is applied to a plasma etching apparatus is shown as an example, but the present invention is not limited to such an apparatus, a plasma generation apparatus is used, and a CVD apparatus for processing an object to be processed, Any device can be applied as long as it is a device such as an LCD device, a sputtering device or the like that generates a reaction product.

[0035]

According to the present invention, it is possible to clearly set the timing of performing the cleaning step of the member in the processing chamber based on the integrated time of the application time of the high frequency power in the plasma processing apparatus, so that the member can be properly cleaned, It is possible to prevent the deposited matter that adheres to become particles and adhere to the object to be processed, and it is possible to improve the yield of the object to be processed.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a plasma etching apparatus to which a first embodiment according to the present invention is applied.

FIG. 2 is a partial schematic view of a pressing mechanism as the member of FIG.

FIG. 3 is a diagram for explaining the influence of particles attached to an object to be processed by a reaction product attached to a pressing mechanism as a member of FIG.

FIG. 4 is a flowchart illustrating a cleaning procedure of FIG.

5A and 5B are views for explaining the polishing action of the pressing mechanism of FIG.

[Figure 6]

[A] It is a partial schematic view of a pressing mechanism as a conventional member.

FIG. 7B is a partial schematic view of a pressing mechanism as a conventional member.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus (plasma processing apparatus) 2 Processing chamber 4 Mounting table (lower electrode) 18 Member (pressing mechanism (clamp ring)) 31 High frequency power supply 32 Controller 40 Control panel 41 Indication signal 80 Polishing member W Object (semiconductor) Wafer)

Claims (7)

[Claims] 1. A method of cleaning a plasma processing apparatus in which high-frequency power is applied in a reduced-pressure atmosphere to generate a plasma to process an object to be processed, a step of integrating the application time of the high-frequency power, and the integrated time. After a predetermined time or more, a step of outputting an instruction signal for cleaning a member in the processing chamber for processing the object to be processed, and a step of cleaning the member after this step, Method for cleaning plasma processing apparatus. 2. A method of cleaning a plasma processing apparatus, wherein a high frequency power is applied in a reduced pressure atmosphere to generate a plasma to process an object, and a step of integrating the high frequency power application time and the integration time. After a predetermined time or more, a step of outputting an instruction signal for cleaning the member in the processing chamber for processing the object and stopping the application of the high frequency power, and cleaning the member based on the instruction signal The method for cleaning a plasma processing apparatus, comprising: 3. A method of cleaning a plasma processing apparatus, wherein a high-frequency power is applied in a reduced-pressure atmosphere to generate a plasma to process an object, and a step of integrating the application time of the high-frequency power, and the integration time. After a predetermined time or more, a step of outputting an instruction signal for cleaning the member in the processing chamber for processing the object to be processed, and if the object to be processed is being processed or after the object to be processed is processed. In the case of before or after processing, the plasma processing apparatus comprises: a step of stopping the application of the high frequency power after the output of the instruction signal; and a step of cleaning the member based on the instruction signal. Cleaning method. 4. The cleaning of the member is performed by polishing with a polishing member having substantially the same hardness as that of the member, and then cleaning with a cleaning agent. A method for cleaning a plasma processing apparatus as described above. 5. The cleaning method for a plasma processing apparatus according to claim 1, wherein the member is a clamp ring for holding an object to be processed. 6. The method according to claim 1, wherein the integrated time is set to a predetermined time within 100 hours.
Alternatively, the cleaning method of the plasma processing apparatus according to claim 3. 7. The integrated time is set to a time of a member provided in the processing chamber where a cleaning process is performed for the shortest time.
A method for cleaning a plasma processing apparatus as described above.