JP2002134482A - Apparatus and method for plasma processing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an apparatus and a method for plasma processing, capable of preventing an abnormal electric discharging by preventing generation of impurities from the wall surface of a chamber, and stabilizing the plasma. SOLUTION: The apparatus 1 for plasma processing comprises the chamber, made of a conductor such as Al or the like for shutting off the internal atmosphere from the outside air, a bell-jar made of a quartz and covering the inner wall of the chamber, a plasma generating region of a part in the bell-jar, and an exposure/shield controller 9, capable of taking a state in which the conductor part is exposed with a part of the generating region and in a state which is shielded from the generating region at the conductor part by the insulator part. The method for plasma processing using the apparatus 1 is provided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a plasma processing apparatus for performing plasma processing on a wafer or the like in a process of manufacturing a semiconductor device, and a plasma processing method using the same.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor device, etching or chemical vapor deposition (CVD) is performed.
Various plasma treatments such as a deposition or ashing of a resist are performed. As an example of an apparatus for performing plasma processing on a wafer, FIG. 5 shows electron cyclotron resonance (ECR).
1 shows a schematic diagram of a clotron resonance) plasma etching apparatus.

An ECR plasma etching apparatus 101 shown in FIG. 5 has a magnetic coil 3 around a chamber 2,
A magnetic field is formed in the chamber 2 by the magnetic coil 3. Microwaves are introduced from the waveguide 4 into the chamber 2. The ECR plasma etching apparatus 101 generates a plasma in the chamber 2 using the interaction between the microwave and the magnetic field. When electrons that make a circular motion in a plane perpendicular to the magnetic field satisfy the condition for resonantly absorbing the energy of the electric field (ECR condition), the electrons continue to be accelerated by the high-frequency electric field, and collisions with neutral molecules and ions occur. Kinetic energy increases until it occurs.

[0004] However, in an ECR plasma etching apparatus, it is possible to generate plasma without necessarily satisfying ECR conditions. Therefore, depending on the position of the wafer 5 in the chamber 2, for example, by suppressing the microwave output for the purpose of avoiding damage to the wafer,
The ECR condition may not be satisfied. As shown in FIG. 5, when the wafer 5 is placed on the stage 6 and is placed in the plasma generation region of the chamber 2,
In many cases, ECR conditions are not used.

The chamber 2 is provided with a gas supply unit 7 for supplying an etching gas and a gas exhaust unit 8 for exhausting the gas in the chamber 2. Although not shown, cooling means for cooling the magnetic coil 3 by circulating cooling water is provided around the magnetic coil 3.

In the above etching apparatus, the partition wall 2a of the chamber 2 is usually formed of Al.
A portion of the inside of the partition wall 2a exposed to the plasma is covered with a quartz bell jar 2b. If Al is exposed inside the chamber without forming a quartz bell jar,
During plasma processing, Al is sputtered, and Al or A
In some cases, impurities such as heavy metals contained in l may contaminate the wafer. In addition to the contamination of the wafer by the gasified Al (or impurities in the Al), sputtered Al or the like becomes particles, and the particles adhere to the wafer, thereby causing contamination of the wafer.

On the other hand, quartz has a composition of SiO ₂ and has very few impurities. Therefore, even if quartz is sputtered, no impurity which becomes a contamination source of the silicon substrate is generated. For the above reasons, a quartz bell jar is provided on the inner wall of the chamber for performing the plasma processing on the wafer.

[0008]

However, when the inner wall of the chamber is covered with a quartz bell jar as described above, the generation of plasma tends to be more unstable than when the conductor is exposed in the chamber. In addition, the glow discharge becomes unstable and an abnormal discharge such as an arc discharge is easily caused. Such a phenomenon is often observed particularly at the start of discharge (plasma strike), that is, when the applied voltage is gradually increased and the current suddenly increases, and a light emitting region appears.

[0009] Even after the start of the discharge and the generation of plasma, the above-mentioned instability of the plasma and abnormal discharge are likely to occur depending on the conditions of the plasma processing. For example, when the flow rate of the supply gas into the chamber, the pressure in the chamber, or the microwave output is extremely high or low, the above phenomenon is likely to occur. Plasma generation becomes unstable,
When abnormal discharge occurs, plasma processing such as etching and film formation is performed unevenly in the wafer surface, and damage due to charge accumulation (charge up) on the wafer surface occurs.

[0010] In the conventional plasma processing apparatus, in order to avoid the problem of generation of impurities from the chamber wall surface, the chamber inner wall is completely covered with a quartz bell jar and the plasma is stabilized while sacrificing plasma stability. Therefore, a part of the Al partition, which is a contamination source of the wafer, is exposed inside the chamber.

Therefore, according to the conventional plasma processing apparatus, it is impossible to achieve both reduction of wafer contamination due to impurities, stabilization of plasma and prevention of abnormal discharge. The present invention has been made in view of the above-described problems, and accordingly, the present invention reduces a contamination of a wafer caused by a material of a chamber wall surface, stabilizes plasma, and can prevent abnormal discharge. And a plasma processing method.

[0012]

In order to achieve the above object, a plasma processing apparatus according to the present invention comprises a chamber made of a conductor, which shuts off the internal atmosphere from the outside air, and an insulator, and an inner wall of the chamber. A bell jar, a plasma generation region that is a part of the bell jar, a state in which a conductor portion is exposed in a portion of the plasma generation region, and the conductor portion is separated from the plasma generation region by an insulator portion. Exposure that can take a state of being blocked /
And a shielding control unit.

Preferably, the plasma processing apparatus of the present invention comprises
The conductor portion is a part of the chamber. In the plasma processing apparatus according to the present invention, preferably, the bell jar is a first portion that is a fixed portion that covers an inner wall of the chamber excluding the conductor portion, and a movable portion that includes the insulator portion. And a second portion.

Alternatively, the plasma processing apparatus of the present invention
Preferably, the conductor portion is a portion provided separately from the chamber in the bell jar. In the plasma processing apparatus according to the present invention, preferably, the insulator portion is a movable portion provided separately from the bell jar.

[0015] The plasma processing apparatus of the present invention preferably comprises
The conductor portion may be a single portion formed along the bell jar. Alternatively, in the plasma processing apparatus according to the present invention, preferably, the conductor portion is a plurality of portions scattered along the bell jar. Alternatively, the plasma processing apparatus of the present invention is preferably characterized in that the conductor portion has a needle shape. The plasma processing apparatus according to the present invention is preferably characterized in that the insulator and the insulator portion are made of quartz.

Preferably, the plasma processing apparatus of the present invention comprises
The etching is performed using the plasma. Alternatively, the plasma processing apparatus of the present invention is preferably characterized in that chemical vapor deposition is performed using the plasma. Alternatively, the plasma processing apparatus of the present invention is preferably characterized in that ashing is performed using the plasma.

Thus, it is possible to perform the plasma processing while appropriately switching between a state in which the stabilization of the plasma is prioritized and a state in which the reduction of the contamination by impurities is prioritized. When plasma is generated in a state where the conductor portion is exposed in the plasma emission region, current is discharged to the conductor portion and the plasma is stabilized. Therefore, the plasma processing can be uniformly performed on the surface of the wafer or the like.

When plasma is generated in a state where the conductor portion is shielded by the insulator portion, generation of impurities due to sputtering of the conductor portion is prevented. Therefore, contamination of a wafer or the like on which plasma processing is performed can be prevented.

Further, in order to achieve the above object, a plasma processing method of the present invention comprises the steps of: generating plasma in a first state in which a conductor portion is exposed in a part of a bell jar made of an insulator; Generating a plasma in a second state in which the conductor portion is shielded from inside the bell jar by an insulator portion; and performing a process using plasma in at least one of the first and second states. And

The plasma processing method of the present invention preferably comprises
The processing may include etching. Alternatively, the plasma processing method of the present invention is preferably characterized in that the processing includes chemical vapor deposition. Alternatively, the plasma processing method of the present invention is preferably characterized in that the processing includes ashing. Alternatively, the plasma processing method of the present invention is preferably characterized in that the processing includes cleaning the bell jar.

Thus, when the conductor portion is exposed in the bell jar, current can be discharged to the conductor portion to stabilize the plasma. Therefore, the plasma processing can be uniformly performed on the surface of the wafer or the like. On the other hand, in a state where the conductor portion is shielded by the insulator portion, it is possible to prevent generation of impurities from the conductor portion. Therefore, contamination of the wafer or the like to be subjected to the plasma processing can be prevented.

[0022]

Embodiments of the present invention will be described below with reference to the accompanying drawings. (Embodiment 1) FIG. 1 is a schematic view of an ECR plasma etching apparatus of the present embodiment. The ECR plasma etching apparatus 1 shown in FIG. 1 has a magnetic coil 3 around a chamber 2, and a magnetic field is formed in the chamber 2 by the magnetic coil 3. Microwaves are introduced from the waveguide 4 into the chamber 2. The wafer 5 is placed on the stage 6 and placed in the chamber 2.

The chamber 2 is provided with a gas supply section 7 for supplying an etching gas and a gas exhaust section 8 for exhausting the gas in the chamber 2. Although not shown, cooling means for cooling the magnetic coil 3 by circulating cooling water is provided around the magnetic coil 3.

The partition wall 2a of the chamber 2 is formed of, for example, Al, and a portion of the partition wall 2a exposed to plasma is covered with a quartz bell jar 2b. The partition wall 2a is desirably grounded, but is not necessarily grounded. The ECR plasma etching apparatus 1 of the present embodiment has an exposure / shielding control unit 9 that can be adjusted so that a part of the partition wall 2a is exposed or shielded from the inside of the chamber 2.

FIG. 1 shows an example in which the exposure / shielding control unit 9 is provided at the lower end 9 A of the chamber 2. In addition to the lower end 9A of the chamber, for example, the lower part 9B of the upper magnetic coil 3a
Alternatively, the exposure / shielding control unit 9 can be formed on the upper part 9C of the lower magnetic coil 3b. The exposure / shielding control unit 9 is provided as long as there is no positional obstacle to other members such as the magnetic coil 3.
It can be installed at any place in the chamber 2.

If the partition 2a of the chamber is exposed to plasma while the wafer is subjected to plasma processing, the partition 2a
Is sputtered by the plasma,
Alternatively, impurities such as heavy metals contained in Al may contaminate the wafer. In addition to contamination of the wafer by gasified Al (or impurities in Al), sputtered A
1 and the like become particles, and the particles adhere to the wafer, thereby causing contamination of the wafer. However, if the inside of the partition wall 2a of the chamber is completely covered with the bell jar 2b made of quartz, the plasma cannot be stabilized, and abnormal discharge easily occurs.

According to the ECR plasma etching apparatus 1 of this embodiment, a part of the partition wall 2a made of a conductive material can be exposed in the chamber 2 as necessary, for example, for starting discharge. Alternatively, the conductor portion can be exposed inside the quartz bell jar 2b. Thereby, the plasma can be stabilized, and occurrence of abnormal discharge can be prevented.

Further, according to the ECR plasma etching apparatus 1 of the present embodiment, the inner wall of the chamber can be completely covered with quartz while the plasma processing is performed on the wafer after the plasma is generated. Since quartz has a composition of SiO ₂ and has very few impurities, even if the quartz is sputtered, no impurity which becomes a contamination source of the silicon substrate is generated. Therefore, contamination of the wafer due to the sputtering of the partition walls is prevented.

The ECR plasma etching apparatus 1 generates plasma in the chamber 2 by utilizing the interaction between a microwave and a magnetic field. When electrons that make a circular motion in a plane perpendicular to the magnetic field satisfy the condition for resonantly absorbing the energy of the electric field (ECR condition), the electrons continue to be accelerated by the high-frequency electric field, and collisions with neutral molecules and ions occur. Kinetic energy increases until it occurs.

However, in the ECR plasma etching apparatus, it is possible to generate plasma without necessarily satisfying the ECR conditions. Therefore, depending on the position of the wafer 5 in the chamber 2, for example, by suppressing the microwave output for the purpose of avoiding damage to the wafer,
The ECR condition may not be satisfied.

(Embodiment 2) FIG. 2 to FIG.
It is an enlarged view of the shielding control part 9, and shows a different structural example, respectively. According to the structure of the exposure / shielding controller 9a shown in FIGS. 2A and 2B, the fixed quartz bell jar 2b is provided so that the vicinity of the lower end of the chamber partition 2a is exposed in the chamber 2. Assuming that the lower limit of the plasma reachable range is the position indicated by the dotted line in FIG. 2, the fixed quartz bell jar 2b is arranged so that the lower end is higher than the dotted line.

A movable quartz bell jar 2c is formed on the inner periphery of the fixed quartz bell jar 2b, and the movable quartz bell jar 2c is vertically movable by an elevating mechanism 10.
As shown in FIG. 2A, when the movable quartz bell jar 2c rises and the upper end of the movable quartz bell jar 2c becomes higher than the lower end of the fixed quartz bell jar 2b, the Al partition wall 2 is moved.
a is shielded from the inside of the chamber 2. On the other hand, FIG.
As shown in (b), when the movable quartz bell jar 2c is lowered and the upper end of the movable quartz bell jar 2c is lower than the lower end of the fixed quartz bell jar 2b, a part of the Al partition 2a is exposed in the chamber 2. .

The fixed quartz bell jar 2b and the movable quartz bell jar 2c are arranged concentrically when viewed from above, and the distance between the two bell jars 2b, 2c in the radial direction of the concentric circle does not hinder the elevation of the movable quartz bell jar 2c. Make it the smallest in the range. Thereby, when the exposure / shielding control unit 9a is shielded, the Al partition 2a is connected to the two bell jars 2a.
Exposure to plasma from the gaps b and 2c can be minimized. Therefore, sputtering of the Al partition 2a by plasma and generation of impurities due to the sputtering are prevented.

At least one of the vicinity of the lower end of the fixed quartz bell jar 2b and the vicinity of the upper end of the movable quartz bell jar 2c can be formed thicker than other portions of the bell jar. FIG. 2 shows an example in which the vicinity of the lower end of the fixed quartz bell jar 2b is formed thick. As shown in FIG. 2, by forming at least one end of the bell jars 2 b and 2 c to be thick, the Al partition wall 2 a can also be formed by the two bell jars 2 b and 2 c.
Exposure to plasma from the gap c can be minimized.

(Embodiment 3) According to the structure of the exposure / shielding control section 9b shown in FIGS. 3A and 3B, the inner wall of the chamber partition wall 2a made of Al is completely covered.
The fixed quartz bell jar 2b is formed. A conductor portion 11 is provided on the inner periphery of the fixed quartz bell jar 2b so as to cover the vicinity of the lower end of the fixed quartz bell jar 2b. As in FIG. 2, when the lower limit of the plasma reachable range is the position indicated by the dotted line, the conductor portion 11 is arranged so that the upper end is higher than the dotted line. A cap portion 12 made of quartz is formed on the upper end of the conductor portion 11. It is desirable that the conductor portion 11 is grounded.

A movable quartz bell jar 2c is formed on the inner periphery of the conductor portion 11, and the movable quartz bell jar 2c is vertically movable by an elevating mechanism 10. FIG. 3 (a)
As shown in FIG. 7, the movable quartz bell jar 2c rises, the upper end of the movable quartz bell jar 2c and the upper end of the conductor portion 11 become almost the same height, and when the upper end of the movable quartz bell jar 2c contacts the cap portion 12, the conductor Part 11 is chamber 2
Shielded from inside. On the other hand, as shown in FIG. 3B, when the movable quartz bell jar 2c descends, the conductor portion 1
1 is exposed in the chamber 2.

The fixed quartz bell jar 2b, the conductor portion 11, and the movable quartz bell jar 2c are arranged concentrically when viewed from above. The distance between the fixed quartz bell jar 2b and the conductor portion 11 in the radial direction of the concentric circle is made as small as possible. Thus, when the exposure / shielding control unit 9b shields, it is possible to minimize exposure of the outer wall surface of the conductor unit 11 to plasma. Also, as shown in FIG. 3C, by exposing the cap portion 12 to the fixed quartz bell jar 2b, it is possible to minimize the exposure of the wall surface on the outer peripheral side of the conductor portion 11 to plasma. it can.

According to the structure of the exposure / shielding control section 9b of this embodiment, it is possible to use a material different from the material of the chamber partition 2a as the material of the conductor section 11. With the structure that can hold the movable quartz bell jar 2c at an arbitrary position, the degree of exposure of the conductor portion 11 can be arbitrarily adjusted according to the movable range of the movable quartz bell jar 2c. Further, when the conductor portion 11 is consumed by being exposed to the plasma, only the conductor portion 11 can be replaced.

(Embodiment 4) Instead of forming the conductor portion 11 of the exposure / shielding control portion 9b shown in Embodiment 3 in a ring shape along the chamber partition 2a, it is formed partially as viewed from above. You can also. Alternatively, the conductor portions may be scattered at a plurality of locations along the chamber partition. In this case, a movable quartz bell jar may be provided on the inner peripheral side of the conductor portion as in the third embodiment, or a movable quartz portion covering only the conductor portion and its vicinity may be provided.
Either may be used.

In the structure of the exposure / shielding control unit of the present embodiment, the degree of exposure of the conductor is arbitrarily adjusted. The movable quartz part may have a structure movable in the horizontal direction by, for example, a rotating mechanism or a sliding mechanism, in addition to the structure movable up and down by the elevating mechanism similarly to the movable quartz bell jar of the third embodiment.

(Embodiment 5) The conductor portion 11 of the exposure / shielding controller 9b shown in Embodiment 3 has a shape in which a plate-like conductor is bent along a curved surface. Shapes other than the plate shape can also be used. For example, as shown in FIG. 4, by forming the needle-shaped conductor portion 13, it is possible to capture the current in the chamber, limit the transient overvoltage at the start of discharge, and stabilize the plasma. it can.

According to the structure of the exposure / shielding control section 9c of this embodiment, the opening 2e is provided in the fixed quartz section 2d, and the tip of the needle-shaped conductor section 13 is disposed in the opening 2e. The fixed quartz portion 2d may be the same as the quartz bell jar 2b of the first embodiment, or may be a ring-shaped or plate-shaped quartz member provided further inside the quartz bell jar 2b. May be.

A movable quartz portion 2f is provided on the inner peripheral side of the opening 2e. As the movable quartz part 2f moves,
The exposure or shielding of the opening 2e is controlled. In the present embodiment, similarly to the fourth embodiment, the moving direction of the movable quartz portion 2f is not limited to the vertical direction, and may be a mechanism that moves in the horizontal direction.

(Embodiment 6) An example of a process in the case where the plasma processing apparatus shown in Embodiment 1 is applied to etching of polysilicon will be described. a. Stabilization Step First, the etching gas is introduced and the pressure in the chamber is stabilized. At this stage, the chamber partition 2a made of a conductor
Or the conductive portion of the exposure / shielding control section 9 is exposed to the inside of the chamber.

B. The conductive portion using phase applied voltage gradually increased immediately after discharge has started, or after the plasma is stabilized, actuates the exposure / shielding control unit 9 for shielding the chamber partition wall 2a or conductive portion. c. Normal processing stage Predetermined etching conditions (for example, microwave power 120
0W, coil current 15A, high frequency output 100W, pressure 5
mTorr (≒ 0.67 Pa), Cl ₂ gas flow rate 100
The polysilicon is etched at a flow rate of sccm and an O ₂ gas flow rate of 10 sccm). The above steps a to c are repeated as necessary each time the plasma is ignited.

(Embodiment 7) This embodiment relates to Embodiment 1.
Another process example in the case where the plasma processing apparatus described above is applied to etching of polysilicon is shown. According to the process example of the present embodiment, in the polysilicon etching, a part of the chamber partition wall or the conductor portion is exposed in the chamber in the breakthrough step. Subsequent main etching and overetching are performed with the conductor portion shielded by quartz.

First, a. Similarly to the stabilization step, the etching gas is introduced and the pressure in the chamber is stabilized while part of the chamber partition wall 2a made of a conductor or the conductor part of the exposure / shielding control unit 9 is exposed to the inside of the chamber. I do. Next, the applied voltage is increased to start discharging.

After the start of the discharge, a breakthrough step of etching is performed while the exposure / shielding control unit 9 is exposed. The breakthrough is, for example, the microwave output 150
0W, coil current 15A, high frequency output 200W, pressure 3
mTorr (≒ 0.40 Pa), CF ₄ gas flow rate 20 s
ccm, Ar gas flow rate 50 sccm, O ₂ gas flow rate 20
This is performed under the condition of sccm.

After the completion of the breakthrough step, the exposure /
The shielding control unit 9 is operated to shield a part of the chamber partition wall 2a or the conductor portion from the inside of the chamber. Thereafter, for example, c. The main etching is performed under the same conditions as in the normal processing stage. Furthermore, overetching is performed by appropriately changing the etching conditions.

The breakthrough step of the etching is as follows:
The plasma may be generated under unstable conditions, but according to the process of the present embodiment, the plasma is stabilized by exposing the conductor in the chamber in the breakthrough step, and abnormal discharge is prevented. Is suppressed. In addition, in the main etch and the overetch, the conductor is shielded, so that impurity contamination due to sputtering of the conductor is prevented.

(Embodiment 8) When cleaning the inside of the chamber, plasma is often generated under conditions that are significantly different from those of a normal wafer processing process. At this time, generation of plasma may become unstable. In the plasma processing apparatus according to the first embodiment, cleaning of the inside of the chamber is performed by, for example, a microwave output of 2000 W and a coil current of 20 W.
A, high frequency output 0 W, pressure 20 mTorr (≒ 2.67
Pa), Cl ₂ gas flow rate 20 sccm, O ₂ gas flow rate 1
It can be performed under the condition of 00 sccm.

As described above, even when the plasma is generated under the condition that the microwave output and the pressure are higher than those of the normal etching process, the exposure / shielding control unit 9 is operated and a part of the chamber partition wall or the conductive By exposing the body to the inside of the chamber, plasma can be stabilized and abnormal discharge can be prevented.

According to the plasma processing apparatus of the embodiment of the present invention described above, it is possible to perform the plasma processing while appropriately switching between a state where priority is given to stabilization of plasma and a state where priority is given to reduction of contamination by impurities. Become. According to the plasma processing method of the embodiment of the present invention described above, plasma is stably generated when the conductor is exposed in the chamber, and impurities are removed from the conductor when the conductor is shielded from the chamber. It is possible to prevent occurrence.

Embodiments of the plasma processing apparatus and the plasma processing method of the present invention are not limited to the above description. For example, a conductive material other than Al or an Al alloy can be used for the partition wall of the chamber. The plasma processing apparatus of the present invention is not limited to an etching apparatus, but may be, for example, a plasma CVD apparatus or a resist ashing apparatus. In addition, as a process for exposing the conductor in the chamber to generate plasma, other than the above, for example, static elimination of an electrostatic chuck and the like can be mentioned. In addition, various changes can be made without departing from the spirit of the present invention.

[0055]

According to the plasma processing apparatus of the present invention, it is possible to prevent the generation of impurities from the chamber wall surface, stabilize the plasma, and prevent abnormal discharge. ADVANTAGE OF THE INVENTION According to the plasma processing method of this invention, it becomes possible to prevent generation | occurrence | production of the impurity from a chamber wall surface, to stabilize plasma as needed, and to prevent abnormal discharge.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of an ECR plasma etching apparatus according to a first embodiment of the present invention.

2 (a) and 2 (b) show Embodiment 2 of the present invention.
FIG. 2 is a partially enlarged view of FIG.

FIGS. 3A to 3C are views in which FIG. 1 is partially enlarged according to a third embodiment of the present invention.

FIG. 4 is a partially enlarged view of FIG. 1 according to a fifth embodiment of the present invention.

FIG. 5 is a schematic view of a conventional ECR plasma etching apparatus.

[Explanation of symbols]

1, 101 ECR plasma etching apparatus, 2 chamber, 2a partition, 2b fixed quartz bell jar, 2c
.. Movable quartz bell jar, 2d fixed quartz part, 2e opening part, 2f movable quartz part, 3, 3a, 3b magnetic coil,
4 Waveguide, 5 Wafer, 6 Stage, 7 Gas supply unit, 8 Gas exhaust unit, 9, 9a, 9b, 9c Exposure / shield control unit, 9A, 9B, 9C Exposure / shield control Part position,
10 lifting mechanism, 11 conductor part, 12 cap part,
13 ... needle-shaped conductor part.

Claims (17)

[Claims] A chamber made of a conductor, which shields an internal atmosphere from outside air; a bell jar made of an insulator, which covers an inner wall of the chamber; a plasma generation region which is a part of the bell jar; A plasma processing apparatus comprising: an exposure / shielding control unit capable of setting a state in which a conductor portion is exposed to a part of a plasma generation region and a state in which the conductor portion is shielded from the plasma generation region by an insulator portion. 2. The plasma processing apparatus according to claim 1, wherein said conductor portion is a part of said chamber. 3. The bell jar has a first portion that is a fixed portion that covers an inner wall of the chamber excluding the conductor portion, and a second portion that is a movable portion including the insulator portion. Item 3. A plasma processing apparatus according to Item 2. 4. The plasma processing apparatus according to claim 1, wherein said conductor portion is a portion provided separately from said chamber in said bell jar. 5. The plasma processing apparatus according to claim 4, wherein said insulator portion is a movable portion provided separately from said bell jar. 6. The plasma processing apparatus according to claim 5, wherein said conductor portion is a single portion formed along said bell jar. 7. The plasma processing apparatus according to claim 5, wherein said conductor portion is a plurality of portions scattered along said bell jar. 8. The plasma processing apparatus according to claim 5, wherein said conductor portion has a needle shape. 9. The plasma processing apparatus according to claim 1, wherein said insulator and said insulator portion are made of quartz. 10. The plasma processing apparatus according to claim 1, wherein etching is performed using said plasma. 11. The plasma processing apparatus according to claim 1, wherein chemical vapor deposition is performed using said plasma. 12. The plasma processing apparatus according to claim 1, wherein ashing is performed using said plasma. 13. A part of a bell jar made of an insulator,
Generating plasma in a first state in which a conductor portion is exposed; generating plasma in a second state in which the conductor portion is shielded from inside the bell jar by an insulator portion; A plasma processing method for performing processing using plasma in at least one of the second states. 14. The process of claim 13, wherein said processing includes etching.
The plasma processing method as described above. 15. The method of claim 1, wherein said processing comprises chemical vapor deposition.
4. The plasma processing method according to 3. 16. The method according to claim 13, wherein said processing includes ashing.
The plasma processing method as described above. 17. The plasma processing method according to claim 13, wherein the processing includes cleaning the bell jar.