JP2005277397A - Plasma processing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the propagation rate of a detector 50 to a pickup antenna 51 without thinning the wall of a processing vessel or changing the size and length of a hole penetrating the wall in detecting the electromagnetic wave generated in abnormality of plasma such as abnormal discharge in a plasma processing apparatus, since the inside of a hole 40 is filled with a dielectric. <P>SOLUTION: This plasma processing apparatus has a dielectric with at least a part facing the space in the processing vessel of the plasma processing apparatus and a detector having a pickup antenna 51 for receiving the electromagnetic wave generated in abnormal plasma in the processing vessel through the dielectric. In the sidewall 5 of the processing vessel, a penetrating hole 40 is formed. In the hole 40, there is airtightly provided a window member 41 comprising the dielectric. An insertion part 41b fills the inside of the hole 40. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a plasma processing apparatus.

  2. Description of the Related Art Conventionally, plasma processing apparatuses have been proposed in which plasma is generated in a processing container using microwaves or other high-frequency waves, and various types of plasma processing such as CVD processing and etching processing are performed on a substrate in the processing container. Yes.

  In plasma processing, if the plasma generated in the processing vessel has an abnormal discharge, the plasma density uniformity may be impaired or the plasma processing itself may not be performed properly. Therefore, conventionally, an apparatus including a detection device for monitoring the plasma state outside the processing container has been proposed (Patent Document 1). This detection device detects an electromagnetic wave having a frequency generated by the abnormal discharge different from the plasma when an abnormal discharge is generated in the processing container, thereby determining the presence or absence of an abnormality in the plasma state.

  Such a detection device is provided with an antenna or the like for picking up electromagnetic waves at the time of abnormal discharge. However, since the detection device itself cannot be installed in the processing container, conventionally, for example, the wall of the processing container, A through-hole called a port is formed in a side wall or the like, and the outer side (for example, the atmosphere side) of the through-hole is hermetically covered with a window member such as a dielectric, and a detection device is installed outside the window member ( Patent Document 2). The pickup antenna of the detection device receives the electromagnetic wave propagating through the through hole and sends the electromagnetic wave signal to a predetermined circuit or the like.

By the way, the cross-sectional size of the through hole is designed to be as small as possible in consideration of the influence on the process. However, for high frequencies, such a through hole functions as a kind of waveguide, and a frequency signal lower than the cut-off frequency (the lower limit frequency when the electric field conductivity is 1) can reach the pickup antenna sufficiently. There may be no. For example, in the case of a through-hole having a diameter of 10 mm and a length of about 30 mm that is often used as this type of detection port, the cutoff frequency in the lowest TE ₁₁ mode is 8.8 GHz. Then, the signal detection means is limited, and an expensive measuring instrument is required. Furthermore, since the lower limit of the high frequency band generated in the case of abnormal discharge phenomena such as arcs and sparks is relatively low, for example, several kHz, it is desirable to detect even a lower frequency band when detecting minute abnormal discharge.

  On the other hand, if the length of the through hole is shortened, in other words, if the wall of the processing container is thinned, the transmission rate is improved, but this causes a problem in the strength of the processing container itself. Since this type of plasma processing is performed at a reduced pressure level close to a vacuum, there is a limit to reducing the thickness of the wall constituting the processing vessel in terms of strength.

Japanese Patent Application Laid-Open No. 9-266098 Japanese Patent Application Laid-Open No. 10-168568

  The present invention has been made in view of the above points, and in detecting plasma abnormality such as abnormal discharge in the processing vessel through such a through-hole, the detection device is made without reducing the wall of the processing vessel. It aims at improving the propagation rate to the pickup antenna.

  In order to achieve the above object, the plasma processing apparatus of the present invention comprises at least a part of a dielectric that faces the space in the processing container of the plasma processing apparatus and electromagnetic waves generated during abnormal plasma in the processing container. And a detection device having a pickup antenna for receiving through the body.

  A hole penetrating the wall of the processing container, a window member that airtightly covers the outer side of the hole, and a detection device having a pickup antenna that receives electromagnetic waves generated during abnormal plasma through the hole, Furthermore, the inside of the hole may be filled with a dielectric.

  The conventional holes are hollow and have an atmosphere close to a vacuum, which is the same as the degree of decompression in the processing vessel. Therefore, by receiving electromagnetic waves through the dielectric, or by filling the holes with a dielectric, the propagation rate of electromagnetic waves generated in the event of plasma abnormalities such as abnormal discharge to the pickup antenna is improved. Can do. In this case, since the cut-off frequency becomes lower in inverse proportion to the square root of the dielectric constant, the higher the relative dielectric constant (dielectric constant of the dielectric / dielectric constant of the vacuum) of the dielectric to be filled is better. If the relative dielectric constant is about 3.7 or more, the practicality is high.

  The pickup antenna of the detection device may be arranged in a dielectric body that fills the hole. As a result, the pickup antenna receives the signal closer to the location where abnormal discharge or the like occurs than before, and the propagation rate to the pickup antenna is improved and the sensitivity is improved.

  An electromagnetic wave propagation member independent of the pickup antenna of the detection device may be disposed in the dielectric. Thus, even if an electromagnetic wave propagation member that is independent of the pickup antenna, that is, not connected to the pickup antenna, is disposed, the propagation rate of the electromagnetic wave to the detection device is improved. Examples of the electromagnetic wave propagating member include metal wires and rods similar to the antenna.

  According to another aspect of the present invention, the present invention provides a plasma processing apparatus for performing plasma processing on a substrate in a processing container, wherein a hole penetrating a wall of the processing container and an outer side of the hole are provided. And a detection device having a pickup antenna that receives electromagnetic waves generated during abnormal plasma through the hole, and the pickup antenna is covered with a covering member made of a dielectric material and has the hole. The clearance gap exists between the outer peripheral surface of the said covering member, and the inner peripheral surface of the said hole.

  When the pickup antenna is covered with a dielectric covering member and disposed in the hole, the hole does not need to be completely filled with the dielectric, and there may be a gap between the inner surface of the hole. And by picking up and arranging the pickup antenna together with the covering member in the hole in this way, the pickup antenna can receive at a position closer to the place where the abnormality of plasma such as abnormal discharge occurs than before. The propagation rate to the antenna is improved and the sensitivity is improved.

  Similarly, if the electromagnetic wave propagation member is covered with a covering member made of a dielectric material and inserted into the hole, it is not necessary to completely fill the hole with the dielectric material. And the tip part of the covering member covering the pickup antenna and the electromagnetic wave propagation member in this manner may protrude from the hole to the inside of the processing container. Thereby, the sensitivity can be further increased.

  It is preferable that the dielectric filling the inside of the hole and the dielectric constituting the covering member are made of the same material as the window member. This is because when electromagnetic waves pass through the interface of different dielectrics, reflection occurs at the interface.

  According to the present invention, the sensitivity of the pickup antenna is improved without reducing the thickness of the wall of the processing container or increasing the size of the hole itself, and the frequency band of the cutoff frequency is made lower than before. Therefore, it is possible to detect an abnormal discharge or an abnormal plasma state in the processing vessel with higher accuracy than in the past.

  Hereinafter, embodiments of the present invention will be described. FIG. 1 shows a state of a longitudinal section of a plasma processing apparatus 1 according to the present embodiment, and this plasma processing apparatus 1 includes a bottomed cylindrical processing container 2 made of, for example, aluminum and having an open top. Yes. The processing container 2 is grounded. A susceptor 3 for placing, for example, a semiconductor wafer (hereinafter referred to as a wafer) W as a substrate is provided at the bottom of the processing container 2. The susceptor 3 is made of a metal such as aluminum, for example, and is supplied with a high frequency for bias from an AC power supply 4 provided outside the processing container 2. The susceptor 3 may be made of ceramics such as AlN and SiC. Furthermore, a heater capable of heating the substrate on the susceptor may be incorporated in the susceptor 3.

  An exhaust pipe 12 for exhausting the atmosphere in the processing container 2 by an exhaust device 11 such as a vacuum pump is provided at the bottom of the processing container 2. Further, a gas introduction unit 13 such as a gas nozzle for supplying a processing gas from a processing gas supply source 15 is provided on the side wall of the processing container 2.

  In the upper opening of the processing container 2, a transmission window 20 made of, for example, a quartz member is provided via a sealing material 14 such as an O-ring for ensuring airtightness. Instead of the quartz member, other dielectric materials such as ceramics such as AlN and sapphire may be used. A processing space S is formed in the processing container 2 by the transmission window 20. The transmission window 20 has a circular planar shape.

  A planar antenna member, for example, a disk-shaped slot antenna 30 is provided above the transmission window 20, and a slow wave plate 31 is disposed on the upper surface of the slot antenna 30. A conductive cover 32 is provided for covering. The slot antenna 30 is made of a thin copper plate plated or coated with a conductive material such as Ag, Au, etc., and a large number of slits 33 are formed, for example, in a spiral or concentric pattern. .

  A coaxial waveguide 35 is connected to the cover 32, and the coaxial waveguide 35 includes an inner conductor 35a and an outer tube 35b. The inner conductor 35a is connected to the slot antenna 30. The inner conductor 35a has a conical shape on the slot antenna 30 side, and efficiently propagates microwaves to the slot antenna 30. The coaxial waveguide 35 transmits, for example, 2.45 GHz microwave generated by the microwave supply device 36 through the load matching device 37, the coaxial waveguide 35, the slow wave plate 31, and the slot antenna 30. Propagate to window 20. Then, an electric field is formed on the lower surface of the transmission window 20 by the energy, and the processing gas supplied into the processing container 2 by the gas introduction unit 13 is turned into plasma, and a predetermined plasma processing is performed on the wafer W on the susceptor 3. For example, a substrate modification process such as a film forming process or an etching process is performed.

  A hole 40 penetrating the side wall 5 is formed above the side wall 5 of the processing container 2. As shown in FIG. 2, a window member 41 is provided on the outer side of the hole 40 through a seal member 42 such as an O-ring so as to hermetically seal the outer side of the hole 40. The window member 41 includes a locking portion 41 a that is locked at the outer peripheral portion of the hole 40 and an insertion portion 41 b that is inserted into the hole 40 in an airtight manner. The window member 41 is made of a dielectric material such as quartz glass. The hole 40 is filled with the insertion portion 41b.

  A detection device 50 is provided outside the window member 41. A pickup antenna 51 for picking up electromagnetic waves is built in the detection device 50.

  As a material of the pickup antenna 51, a conductive metal such as copper, platinum, gold, or silver is used. Further, a member such as Al, SUS, ceramics, or resin coated with these materials may be used.

  The frequency signal received by the pickup antenna 51 is output to a signal processing device 52 installed outside the processing container 2, and the signal processing device 52 processes the frequency signal to check whether there is an abnormal discharge or the like. Detected. The pickup antenna 51 may be provided in the window member 41 as shown.

  Next, a control system of the plasma processing apparatus 1 will be described. The AC power supply 4, the exhaust device 11, the processing gas supply source 15, the microwave supply device 36, and the signal processing device 52 are all controlled by the control device C. As a result, for example, the pressure in the processing container 2 can be set to a predetermined pressure value, and if an abnormal discharge is detected by the signal processing device 52, the processing gas supply source 15 supplies the processing gas. Supply, microwave supply from the microwave supply device 36 is automatically stopped.

  The plasma processing apparatus 1 according to the present embodiment has the above-described configuration. When performing plasma processing, the wafer W is placed on the susceptor 3 in the processing container 2 and a predetermined amount is introduced from the gas introduction unit 13. While the processing gas is supplied into the processing container 2, the processing space S is brought to a predetermined pressure by exhausting from the exhaust pipe 12.

  Then, a high frequency bias is applied to the wafer W by the AC power source 4, and a microwave is generated by the microwave supply device 36, and the microwave is introduced into the processing container 2 through the transmission window 20 and below the transmission window 20. By generating an electric field, the processing gas in the processing space S is turned into plasma, and by selecting the type of processing gas or the like, a predetermined plasma processing such as oxidation processing, nitriding processing, acid processing, etc. is performed on the wafer W. Various plasma processes such as a nitriding process, an etching process, an ashing process, and a film forming process can be performed.

  In the plasma processing apparatus 1 according to the present embodiment, when detecting a plasma abnormality such as abnormal discharge generated in the processing container 2 through the hole 40 by the detection apparatus 50, the inside of the hole 40 is made of a dielectric. Since the filling portion 41b of the window member 41 is filled, the propagation rate of the electromagnetic wave generated at the time of abnormal discharge to the pickup antenna 51 is improved as compared with the case where the inside of the hole remains hollow. The sensitivity of the pickup antenna 51 is improved. Therefore, it is possible to detect an abnormal discharge or an abnormal plasma state in the processing container 2 with higher accuracy than before. Moreover, since this can be realized without increasing the size of the hole 40 or reducing the thickness of the side wall 5 of the processing vessel 2, it can be applied to this kind of existing plasma processing apparatus.

  The detection device 50 may be provided anywhere in the processing container 2 as long as it can detect electromagnetic waves, such as the bottom, top, and susceptor part of the processing container 2 as well as the side wall 5.

When the inventors actually calculated and examined the effect of the present invention, the results shown in the graph of FIG. 3 were obtained. The graph shows the frequency-electric field propagation rate for the pickup antenna 51 when the diameter of the hole 40 is 10 mm and the thickness of the side wall 5 (the length of the hole 40) is 30 mm. Note that the material of the window member 41, the quartz member (dielectric constant 3.75) using a measurement was based on _{TE 11} mode.

  According to this, the cutoff frequency is about 8.8 GHz in the conventional technique (with the inside of the hole 40 being hollow), whereas in this embodiment, the cutoff frequency is about 4.2 GHz, and the cutoff frequency is about half or less. It was found that the frequency can be lowered. Also, overall, it can be seen that in the case of the same frequency, the propagation rate is improved in the present embodiment. Therefore, a frequency lower than that of the prior art can be detected and the sensitivity is improved, so that an abnormal discharge or an abnormal state of plasma in the processing vessel 2 can be detected with higher accuracy than in the past.

In the above-described embodiment, the material of the window member 41 is made of a quartz member. However, the material is not limited to this, and other dielectrics such as alumina (relative dielectric constant: 9.9), AlN, Si ₃ N ₄ , fluorine The window member 41 may be made of a system resin or other resin. The higher the relative dielectric constant, the more the propagation rate can be improved. Or it may be used after coating the Y ₂ O ₃ with excellent plasma resistance to these materials.

  In the above embodiment, the hole 40 is simply filled with the insertion portion 41b of the window member 41 made of a dielectric. However, in order to further improve the propagation rate, for example, the example shown in FIG. be able to. In the example of FIG. 4, a cavity 43 is further formed inside the insertion portion 41 b of the window member 41 with respect to the structure shown in FIG. 2, and the pickup antenna 51 is electrically connected to the cavity 43. Another pickup antenna 44 is provided.

  According to such an example, since the electromagnetic wave generated in the processing container 2 can be received at a place closer to the processing space S in the processing container 2, the propagation rate is further improved. In the example of FIG. 4, the pickup antenna 44 is provided separately from the pickup antenna 51 in the detection device 50. However, the pickup antenna 51 in the detection device 50 is not provided and is arranged in the insertion portion 41 b. The pickup antenna 44 may be provided, and the received frequency signal may be output to the signal processing device 52. That is, instead of the pickup antenna 51, only the pickup antenna 44 may be provided.

  Further, in the example shown in FIG. 4, as a result, a pickup antenna having a receiving function is arranged in the insertion portion 41b. However, as shown in FIG. An electromagnetic wave propagation member 45 that is not electrically connected to the pickup antenna 51 may be installed. The electromagnetic wave propagation member 45 can employ, for example, a conductive wire or bar.

  When the electromagnetic wave propagation member 45 is installed in this manner, the electromagnetic wave attenuation is suppressed by the electromagnetic wave propagation member 45, and as a result, the propagation rate to the pickup antenna 51 in the detection device 50 is improved, and the sensitivity is improved.

  4 and 5, the insertion portion 41b of the window member 41 has a size and shape that fills the inside of the hole 40. However, as shown in FIG. 6, the outer diameter of the insertion portion 41b is reduced. As a result, a gap d may be formed between the outer peripheral surface of the insertion portion 41 b and the inner peripheral surface of the hole 40. The insertion portion 41b in this case constitutes a covering member as referred to in the present invention. As described above, the dielectric filling the hole 40 and the dielectric constituting the covering member are preferably made of the same material as the window member 41. This is because when electromagnetic waves pass through the interface of members having different dielectric materials, reflection occurs at the interface.

  In the example of FIG. 6, the example which provided the pick-up antenna 44 in the cavity 43 of the insertion part 41b is shown. In the example of FIG. 6, only the pickup antenna 44 may be arranged without providing the pickup antenna 51. In the example of FIG. 7, the example which provided the electromagnetic wave propagation member 45 in the hollow part 43 of the insertion part 41b is shown.

  In the examples shown in FIGS. 4 and 5, since the pickup antenna 44 receives the signal and the electromagnetic wave propagation member 45 suppresses the attenuation of the electromagnetic wave, not all of the inside of the hole 40 becomes a propagation path. 6 and 7, there is no problem in detection even if there is a gap d.

  Further, in the examples of FIGS. 6 and 7, the distal end portion of the insertion portion 41b has a shape protruding from the hole 40 to the inside of the processing container 2, and the distal ends of the pickup antenna 44 and the electromagnetic wave propagation member 45 further enter the processing space. Located in a nearby location. Therefore, since the detection can be performed at a position closer to the processing space than in the case of FIGS. 4 and 5, the propagation rate can be further improved, and abnormal discharge or the like can be detected with high accuracy.

  As described above, the present invention efficiently propagates the electromagnetic wave generated during abnormal discharge to the pickup antenna. By utilizing this, various plasma treatments such as plasma oxidation treatment, It is also possible to detect the end of the process itself during the plasma nitriding process, the plasma etching process or the plasma CVD process.

  For example, in the case of a plasma etching process, an electromagnetic wave based on a certain etchant is always detected and monitored by the detection device 50, and it is detected when the etchant does not contribute to etching and when it contributes. Differences occur in the electromagnetic waves. That is, a change is recognized between the electromagnetic wave detected before the etching process and the electromagnetic wave detected during the etching process. Therefore, when the etching is completed, the detected electromagnetic wave returns to the electromagnetic wave detected before the etching process. By using this, it is possible to detect the end point of etching, the so-called end point. .

For plasma CVD processing, an electromagnetic wave at a predetermined film thickness is detected in advance as a reference value, and the detected value is detected by detecting the electromagnetic wave constantly by the detecting device 50 during the CVD processing and monitoring it. If the value is reached, it can be confirmed that the predetermined film thickness has been reached. That is, it can be detected that the intended CVD process has been completed.
Hereinafter, examples of the plasma etching process and the plasma CVD process using the plasma processing apparatus 1 will be described.

Examples of plasma etching processes include
(1) W (tungsten) etching wafer W temperature: room temperature (23 ° C.) or less power: 1000 W to 5000 W
Processing pressure: 0.133 Pa to 133 Pa
Processing gas: Cl ₂ / N ₂ / O ₂ = 150/150/20 sccm
Or Ar / Cl ₂ / N ₂ / O ₂ = 200/100/75/5 sccm
(2) Temperature of polysilicon etching wafer W: Room temperature (23 ° C.) or less Power: 1000 W to 5000 W
Processing pressure: 0.133 Pa to 133 Pa
Processing gas: HBr = 300 sccm
Or Ar / HBr / O ₂ = 1200/400/100 sccm
SF6 may be used.

As an example of plasma CVD processing,
(1) Low-K film (CF film)
Temperature of wafer W: Room temperature (23 ° C.) or less Power: 1000 W to 5000 W
Processing pressure: 1.33 Pa to 133 Pa
Process gas: Ar / C ₅ F ₈ = 300/300 sccm

  For example, in each of the etching process and the CVD process as described above, a so-called end point of each process can be detected by observation of electromagnetic waves.

  The above embodiment is configured as a plasma processing apparatus using microwaves, and is particularly effective for a plasma processing apparatus having a high plasma source frequency. The present invention is applicable to various types of plasma processing apparatuses including a type (capacitive type) plasma processing apparatus, ECR, ICP plane reflected wave plasma, and ICP.

It is a longitudinal cross-sectional view of the plasma processing apparatus concerning embodiment. It is a longitudinal cross-sectional view near the hole of the side wall of the plasma processing apparatus of FIG. It is a graph which shows the relationship between a frequency and a propagation factor. It is a longitudinal cross-sectional view of the hole vicinity which shows the example by which the pick-up antenna is arrange | positioned in the hole. It is a longitudinal cross-sectional view of the hole vicinity which shows the example by which the electromagnetic wave propagation member is arrange | positioned in the hole. It is a longitudinal cross-sectional view of the hole vicinity which shows the example by which the outer diameter of an insertion part is smaller than the internal diameter of a hole, and the pick-up antenna is arrange | positioned inside. It is a longitudinal cross-sectional view of the hole vicinity which shows the example in which the outer diameter of an insertion part is smaller than the inner diameter of a hole, and the electromagnetic wave propagation member is arrange | positioned inside.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plasma processing apparatus 2 Processing container 3 Susceptor 5 Side wall 41 Window member 41b Insertion part 50 Detection part 51 Pickup antenna W Wafer

Claims (13)

A plasma processing apparatus for performing plasma processing on a substrate in a processing vessel,
A dielectric, at least part of which faces the space in the processing vessel;
A detection device having a pickup antenna for receiving electromagnetic waves generated when the plasma in the processing container is abnormal via the dielectric;
A plasma processing apparatus comprising: A hole penetrating the wall of the processing vessel;
A window member that airtightly covers the outside of the hole,
The plasma processing apparatus according to claim 1, wherein at least the inside of the hole is filled with the dielectric. The window member is made of a dielectric;
Further, the window member has a locking portion locked to the hole outside the processing container, and an insertion portion that is inserted into the hole and fills the hole. The plasma processing apparatus according to claim 2. The plasma processing apparatus according to claim 1, wherein the pickup antenna is disposed in the dielectric body. The plasma processing apparatus according to claim 1, further comprising another pickup antenna disposed in the dielectric body and electrically connected to the pickup antenna of the detection apparatus. The plasma processing apparatus according to claim 1, further comprising an electromagnetic wave propagation member disposed in the dielectric body and independent of a pickup antenna of the detection apparatus. A plasma processing apparatus for performing plasma processing on a substrate in a processing vessel,
And a detection device having a hole penetrating the wall of the processing container, a window member that airtightly covers the outer side of the hole, and a pickup antenna that receives electromagnetic waves generated when a plasma abnormality occurs through the hole. ,
The pickup antenna is covered with a covering member made of a dielectric material and disposed in the hole,
A plasma processing apparatus, wherein a gap exists between an outer peripheral surface of the covering member and an inner peripheral surface of the hole. A plasma processing apparatus for performing plasma processing on a substrate in a processing vessel,
And a detection device having a hole penetrating the wall of the processing container, a window member that airtightly covers the outer side of the hole, and a pickup antenna that receives electromagnetic waves generated when a plasma abnormality occurs through the hole. ,
An electromagnetic wave propagating member independent of the pickup antenna of the detection device is covered with a covering member made of a dielectric and disposed in the hole,
A plasma processing apparatus, wherein a gap exists between an outer peripheral surface of the covering member and an inner peripheral surface of the hole. The plasma processing apparatus according to claim 7, wherein a tip end portion of the covering member protrudes from the inside of the hole to the inside of the processing container. The plasma processing apparatus according to claim 2, wherein the dielectric is made of the same material as the window member. The plasma processing apparatus according to claim 1, wherein the plasma processing is a plasma processing generated using a microwave. The plasma processing apparatus according to claim 1, wherein a relative dielectric constant of the dielectric is 3.7 or more. The plasma processing apparatus according to claim 1, further comprising a control device that controls the plasma processing apparatus based on a detection result of the detection apparatus.

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