JP2613313B2 - Microwave plasma processing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus, and more particularly to a microwave plasma processing apparatus in which a discharge means having a plasma generation region inside is separated from a microwave propagation waveguide. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a microwave plasma processing apparatus of a type provided in a wave tube portion, and more particularly to a microwave plasma processing apparatus suitable for performing a process such as an etching process and a film forming process on a sample such as a semiconductor element substrate.

[Prior Art] Conventional microwave plasma processing apparatuses include, for example, those described in Hitachi Review, Vol. 71, No. 5, PP. 33-38 (1989) and Japanese Patent Publication No. 53-34461. Has a quartz discharge tube inside a waveguide that propagates microwaves, generates a plasma in the discharge tube by a synergistic action of a microwave electric field and a magnetic field, and uses the plasma to generate a semiconductor in a processing chamber. There is known one in which a wafer is subjected to an etching process.

Further, for example, Japanese Patent Application Laid-Open Nos. Sho 59-103340 and
As described in No. 25420, etc., having a quartz discharge tube inside a circular waveguide that propagates microwaves, generating plasma by the action of a microwave electric field in the discharge tube,
There is known a method in which a sample such as a semiconductor element substrate in a processing chamber is subjected to an etching process or a film forming process using the plasma.

[Problems to be Solved by the Invention] In the processing of a sample such as a semiconductor element substrate using plasma, unless the plasma density distribution corresponding to the surface to be processed of the sample is made uniform, the processing in the surface to be processed of the sample is not performed. Uniformity cannot be ensured.

Further, according to the findings of the present inventor, for example, in the etching process of an insulator such as a silicon oxide film, the energy contribution degree of active neutral particles such as radicals in plasma is more significant.
Ions having higher energy contribute more to the etching than the active neutral particles. However, if the energy of the ions is too high, the sample is ionically damaged, which is not preferable. Therefore, from the viewpoint of preventing ion damage to the sample, the plasma preferably has energy enough to ionize the processing gas.
In order to improve the processing speed, it is necessary to improve the ionization rate, that is, the plasma density.

On the other hand, in the above-mentioned conventional technology, that is, in the former so-called magnetic field type microwave plasma processing technology and the latter so-called non-magnetic type microwave plasma processing technology, both are made of quartz in the waveguide portion, that is, There is a discharge tube formed of a microwave transmitting material, and the inside of the discharge tube is filled with plasma and the outside is the atmosphere. Therefore, the plasma in the discharge tube contains
Since the waveguide is made of a microwave transmitting material, the microwave propagated through the waveguide is introduced not only from the traveling direction but also from the side of the discharge tube, and the like. The progress is quite complicated. As a result, the uniformity of the plasma density distribution corresponding to the surface to be processed of the sample is impaired, and there is still a problem to be solved such that the uniformity of the processing within the surface to be processed of the sample is reduced. .

On the other hand, to increase the processing speed, it is necessary to increase the plasma density as described above. To address this, there are measures such as changing the processing pressure or increasing the input microwave power.However, in order to further increase the plasma density and improve the processing speed, the above-described conventional technology has limitations. Have. In addition, as the microwave power is increased to improve the processing speed, the uniformity of the plasma density distribution corresponding to the surface to be processed of the sample is further impaired, and the uniformity of the processing within the surface to be processed of the sample is further reduced. The effects on gender decline are even more severe.

SUMMARY OF THE INVENTION An object of the present invention is to improve the uniformity of processing of a sample on a surface to be processed, and to provide a microwave means of a type in which a discharge means having a plasma generation region in a waveguide part is separated from a waveguide which can be secured. An object of the present invention is to provide a plasma processing apparatus.

Another object is to introduce a discharge means having a plasma generation region inside, which is isolated from a waveguide capable of improving and securing the uniformity of the processing of the sample on the surface to be processed and improving the processing speed. An object of the present invention is to provide a type of microwave plasma processing apparatus provided inside a wave tube.

Still another object is to improve the uniformity of the processing on the surface of the sample to be processed, to secure the processing speed, and to improve the processing speed by preventing ion damage. An object of the present invention is to provide a microwave plasma processing apparatus of a type having discharge means having a region in a waveguide portion.

[Means for Solving the Problems] The above object is achieved by means for generating microwaves, a rectangular / circular right-angled conversion waveguide for introducing microwaves from the microwave generating means into a vacuum vessel, Microwave plasma processing comprising a sample stage for holding a sample, a gas supply hole for introducing gas to bring the inside of the vacuum vessel into a plasma state, and a vacuum exhaust device for bringing the inside of the vacuum vessel to a desired vacuum pressure An apparatus, comprising: a discharge block that does not transmit microwaves into the vacuum vessel on an upper surface of the vacuum vessel; and a microwave transmission window provided to hermetically seal a hollow portion provided with the discharge block. Thus, the microwave is transmitted to the vacuum vessel below substantially from the entire surface of the microwave transmitting window, and the microwave impulse is inserted between the rectangular / circular right angle conversion waveguide and the microwave transmitting window. Microwave plasma processing comprising: providing a waveguide forming a space having a height dimension for matching a dance, wherein an inner diameter of the space for impedance matching is larger than a diameter of the microwave transmitting window. Achieved by the device.

[Operation] Discharge means which is separated from the microwave propagation waveguide and has a plasma generation region therein, and a portion corresponding to the traveling direction of the microwave of the discharge means provided in the waveguide portion is a microwave. The other parts are formed of a microwave impermeable material. Therefore, the microwave propagating in the waveguide is not introduced into the discharge means only from the portion of the discharge means formed of the microwave transmitting material.
As a result, the uniformity of the plasma density distribution corresponding to the surface to be processed of the sample is greatly improved as compared with the conventional case where microwaves are introduced from the side and the like, and the sample processed using this is The uniformity of the processing on the surface to be processed is improved.

At the same time, a bias power supply is connected to the sample stage on which the sample is placed, that is, a bias voltage is applied to the sample to accelerate ions incident on the surface to be processed of the sample, thereby improving the processing speed.

Further, the discharge means is separated from the microwave propagation waveguide and has a plasma generation region therein, and a portion corresponding to the microwave traveling direction of the discharge means in the waveguide portion is a microwave. The other portion is made of a microwave impermeable material, and the internal space of the waveguide is a space where microwave impedance matching can be performed. By configuring the discharging means in this way,
As described above, the uniformity of the plasma density distribution corresponding to the surface to be processed of the sample is greatly improved, and the uniformity of the processing of the sample to be processed within the surface to be processed is improved by utilizing the plasma density distribution. At the same time, the reflected wave of the microwave can be made zero.
That is, the microwaves are efficiently absorbed in the plasma generation region of the discharge means. For this reason, the plasma density is increased, and thereby the processing speed is improved.
Furthermore, the acceleration energy of the ions with respect to the sample can be kept low, and the processing speed can be improved with low damage.

Further, the discharge means is separated from the microwave propagation waveguide and has a plasma generation region therein, and a portion corresponding to the microwave traveling direction of the discharge means in the waveguide portion is a microwave. The transmitting portion is formed of a microwave impermeable material, and the other portions are formed of a microwave impermeable material. At least a means for generating a magnetic field applied to the plasma generating region of the discharging means and a means for correcting the magnetic field near the surface of the sample to be processed Provided. In this case, the direction and intensity of the correction magnetic field are further adjusted to correct the plasma density and uniformity, thereby correcting the processing speed and uniformity of the sample.

Further, the discharge means is separated from the microwave propagation waveguide and has a plasma generation region therein, and a portion corresponding to the microwave traveling direction of the discharge means in the waveguide portion is a microwave. The other part is formed of a microwave impermeable material, and the other parts are provided with means for converting microwaves into circularly polarized waves and transmitting the circularly polarized waves to the waveguide. In this case, by further converting the microwave into a circularly polarized wave and propagating it to the waveguide, the plasma generation density in the plasma generation region of the discharge means is greatly improved, and the processing speed of the sample is further reduced. To improve.

Embodiment An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 is a vertical cross-sectional view of a main part of a microwave plasma etching apparatus according to one embodiment of the present invention.

In FIG. 1, the vacuum vessel 10 has a structure in which the top is open. The vacuum vessel 10 is formed of, for example, stainless steel. In this case, the shape of the top opening portion of the vacuum vessel 10 is substantially circular in plan view. An exhaust nozzle 11 is formed in the lower part of the side wall of the vacuum vessel 10. Vacuum exhaust device 20
Is installed outside the vacuum vessel 10. The exhaust nozzle 11 and the intake port of the vacuum exhaust device 20 are connected by an exhaust pipe 21. The exhaust pipe 21 is provided with an on-off valve (not shown), an exhaust resistance variable valve (not shown), and the like.

In FIG. 1, a discharge block 30, which is a means having a plasma generation region inside, is a hollow cylinder whose shape does not change in cross-sectional area with respect to the traveling direction of microwaves. It is formed of a non-magnetic conductive material such as aluminum. The outer dimensions of the discharge block 30 are larger than the dimensions of the open top portion of the vacuum vessel 10. The discharge block 30 has a hollow shaft inside as a substantially vertical axis,
The inner hollow portion of the vacuum vessel 10 is
The inside of the vacuum vessel 10 is airtightly connected to the inside. A microwave transmission window 40 is provided at the top of the discharge block 30 so as to hermetically seal the upper end of the hollow inside thereof. The microwave transmission window 40 is formed of a microwave transmission material such as quartz or alumina. That is, the vacuum container 10
The inside of the discharge block 30 and the microwave transmission window 40
Thus, a space 50 shielded from the outside is formed.

In FIG. 1, a sample stage shaft 60 is provided on the bottom wall of the vacuum vessel 10 with its upper part protruding into the space 50 and the lower part protruding outside the vacuum vessel 10 while maintaining airtightness. . The bottom wall of the vacuum vessel 10 and the sample stage shaft 60 are electrically insulated by an electric insulating member 70. The axis of the sample stage shaft 60 is substantially a vertical axis. The sample stage 61 has a sample setting surface on one surface, in this case, the upper surface. The sample table 61 is provided at the upper end of the sample table shaft 60 with the sample setting surface being substantially horizontal. Note that the sample stage shaft 60 and the sample stage 61 may of course be formed integrally. In this case, outside the space 50, a high-frequency power supply 80 serving as a bias power supply is provided. Sample table axis
60 is connected to a high frequency power supply 80. High frequency power supply 80
Is grounded. The sample stage shaft 60 and the sample stage 60 are formed of a conductive material, and the sample stage 61 is in conduction with the sample stage shaft 60. On the other hand, the vacuum vessel 10 is grounded, and in this case, the discharge block 30 is also grounded via the vacuum vessel 10.
In addition, a DC power supply or the like may be used as the bias power supply. In this case, a coolant channel (not shown) is formed inside the sample table 61, and a coolant supply path (not shown) communicating with the coolant channel is formed inside the sample shaft 60.
Refrigerant discharge paths (not shown) are respectively formed. A coolant supply device (not shown) is provided outside the space 50. The coolant supply port of the coolant supply device and the coolant supply path of the sample stage shaft 60 are connected by a coolant supply pipe (not shown). One end of a refrigerant discharge pipe (not shown) is connected to the refrigerant discharge path of the sample stage shaft 60, and the other end is connected to a refrigerant recovery tank (not shown).
Or open to the atmosphere.

In FIG. 1, a sample mounting surface of the microwave transmission window 40 and the sample table 61, that is, a sample 90 such as a semiconductor element substrate is provided on the sample mounting surface.
In this case, the surface to be processed is vertically opposed to each other, and the surfaces are substantially parallel. Note that the axis of the hollow inside the discharge block 30, the center of the microwave transmitting window 40, and the sample mounting surface of the sample stage 61, that is,
It is desirable that the centers of the surfaces to be processed of the sample 90 are substantially coincident with each other. In this case, the shape of the hollow inside of the discharge block 30 is a shape that is tapered from the middle to the lower end in the height direction of the discharge block 30. This is because the size of the hollow inside the discharge block 30 is smaller than that of the surface of the sample 90 to be processed.
When the size of the internal hollow of the discharge block 30 is larger than that of the surface to be processed of the sample 90, it is necessary to make the shape of the internal hollow of the discharge block 30 a tapered shape as described above. However, it may be substantially the same from the upper end to the lower end in the height direction of the discharge block 30.

In FIG. 1, a gas supply passage 10 is provided inside a discharge block 30.
0 is formed. A processing gas source 101 is provided outside the space 50. The processing gas source 101 and one end of the gas supply path 100 are connected by a gas supply pipe 102. Gas supply pipe 102
Is provided with an on-off valve (not shown), a gas flow controller (not shown), and the like. The other end of the gas supply path 100 is opened to the inside of the discharge block 30 from the upper end in the height direction of the discharge block 30 to the middle thereof.

In FIG. 1, the block 30 is located outside the discharge block 30.
The waveguide 110 is disposed in a state where is included inside. Waveguide 110 terminates in vacuum vessel 10. In this case, the shape of the waveguide 110 is substantially cylindrical. A space 120 having a predetermined height (interval) is formed between the top wall, which is the closed end wall of the waveguide 110, and the upper end surface of the discharge block 30 (the upper surface of the microwave transmission window 40). I have. In this case, a portion of the top wall of the waveguide 110 facing the upper surface of the microwave transmitting window 40 includes:
An opening is formed. Note that the opening does not necessarily need to be provided at the above position. Outside the spaces 50 and 120, a magnetron 130, which is means for oscillating microwaves, is provided. The magnetron 130 and the waveguide 110 are
They are connected by 111 and 112. Waveguides inside waveguides 111 and 112
It is in communication with the impedance matching space 120 through the opening in the top wall of 110. Here, the waveguide 111 has a rectangular shape.
A waveguide for circular right angle conversion, and the waveguide 112 is
It is a rectangular waveguide. The magnetron 130 and the waveguide 110
May be connected by other microwave propagation means, for example, a coaxial cable or the like.

In FIG. 1, air-core coils 140 and 141, which are means for generating a magnetic field, are arranged in a two-stage ring around the side wall of the waveguide 110 in the height direction. Further, in this case, the air core coil 140 substantially corresponds to the space 120, and the air core coil 141 substantially corresponds to the outer peripheral side surface of the discharge block 30. Air core coil 14
Reference numerals 0 and 141 are connected to a power supply (not shown) via an ON-OFF means (not shown), a power supply amount adjusting means (not shown), and the like.

In FIG. 1, the space 50 is evacuated and evacuated by opening the on-off valve and the exhaust resistance variable valve and operating the evacuation device 20. Further, a predetermined etching gas is introduced at a predetermined flow rate from a processing gas source 101 into a hollow inside the discharge block 30 via a gas supply path 100, such as a gas supply pipe 102, an on-off valve, and a gas flow controller. That is, an etching gas is introduced into the space 50. Part of the etching gas introduced into the space 50 is
The gas is exhausted by the vacuum exhaust device 20 by adjusting the opening degree of the exhaust resistance variable valve, whereby the pressure in the space 50 is adjusted to a predetermined etching processing pressure.

In FIG. 1, the sample is transported by a well-known transport means (not shown)
In this case, one 90 is carried into the vacuum vessel 10. The sample 90 carried into the vacuum vessel 10 is transferred from the transfer means to the sample table 61.
Passed to. The transport means having passed the sample 90 is retracted to a place where the processing of the sample 90 is not hindered. The sample 90 transferred to the sample stage 61 is set on the sample setting surface of the sample stage 90 in an upward posture of the surface to be processed. Further, the air-core coils 140 and 141 are activated, and a magnetic field is applied to the hollow inside the discharge block 30.

In FIG. 1, the magnetron 130 is activated, for example, 2.4
A 5 GHz microwave is oscillated. The oscillated microwave is guided to the waveguide 110 after being orthogonally converted from a rectangular mode to a circular mode in the waveguide 111 via the waveguide 112, and further,
The light is propagated into the discharge block 30 only through the microwave transmission window 40. The etching gas in the discharge block 30 is turned into plasma by the synergistic action of the magnetic field and the microwave electric field generated by the air-core coils 140 and 141. The charged particles in the generated plasma are prevented from diffusing in the direction perpendicular to the magnetic field by the strong magnetic field action in the discharge block 30 and rapidly diffuse into the vacuum vessel 10 where the magnetic field is weak, and set on the sample stage 61. The surface of the sample 90 to be processed is covered. Thereby, the surface to be processed of the sample is subjected to a predetermined etching process by the plasma. Further, at this time, by applying a high-frequency bias voltage from the high-frequency power supply 80 to the sample table 61, the + ion species in the plasma are attracted to the sample 90 at the negative cycle of the high-frequency bias and made incident on the surface to be processed. Thus, ion etching can be performed. Further, in the refrigerant flow path inside the sample stage 61,
A predetermined refrigerant (cooling water, refrigerant having a temperature of less than 0 ° C., or the like) is supplied from the refrigerant supply device via a refrigerant supply pipe and a refrigerant supply path. The refrigerant flowing through the refrigerant flow path is collected or discharged to the atmosphere through a refrigerant discharge path and a refrigerant discharge pipe in a refrigerant recovery tank. Thereby, the temperature of the sample 90 is adjusted to a predetermined temperature.

As described above, in this embodiment, since the discharge block formed of the nonmagnetic conductive material is provided in the waveguide, the microwave oscillated from the magnetron and propagated through the waveguide is transmitted through the microwave of the discharge block. It is only introduced from the window into the discharge block. For this reason, the uniformity of the plasma density distribution corresponding to the surface to be processed of the sample can be greatly improved, as compared with a conventional discharge tube in which microwaves are also introduced from the side surface. The uniformity of the treatment can be improved within.

In addition, since the discharge block is formed of a non-magnetic conductive material, the intensity and distribution of the magnetic field generated by the air-core coil inside the discharge block, that is, the magnetic field applied to the plasma generation region, is controlled by the discharge block. As a result, the synergy between the microwave electric field and the magnetic field can be obtained extremely efficiently. For this reason, it is possible to prevent a decrease in the plasma density corresponding to the surface to be processed of the sample and to prevent a reduction in the etching processing speed in the surface to be processed of the sample. In addition, since the discharge block is formed of a non-magnetic conductive material, the strength of the magnetic field applied to the plasma generation region is further increased, and the synergistic action between the microwave electric field and the magnetic field can be further enhanced. For this reason, the plasma density corresponding to the surface to be processed of the sample can be further increased, and the etching processing speed in the surface to be processed of the sample can be further improved. In a non-magnetic field type microwave plasma etching apparatus of a type using only a microwave electric field without using a magnetic field for plasma generation, it is not necessary to form a discharge block with a nonmagnetic conductive material as in the present embodiment. It is sufficient to form it with a conductive material.

In addition, since the inside hollow of the discharge block has a tapered shape, the plasma can be easily diffused in the lateral direction, and a large area of plasma can be obtained accordingly.
This makes it possible to make the etching process of the inner and outer peripheries of the large-diameter sample to be uniform.

In addition, the uniformity of the etching process can be improved in the surface of the sample to be processed, and the ion etching can be performed by applying a bias, so that the etching process speed can be improved.

Note that the distance from the surface to be processed of the sample 90 placed on the sample placement surface of the sample stage 61 to the inner surface of the microwave transmitting window 40 is set to be more stable in order to further stabilize the discharge state inside the discharge block. Desirably, it is at least half of the wavelength in the hollow tube. This makes it possible to more stably improve the uniformity of the etching process in the surface to be processed of the sample.

A second embodiment of the present invention will be described with reference to FIGS.

FIG. 2 is a vertical sectional view showing a main part of a microwave plasma etching apparatus according to a second embodiment of the present invention.

In FIG. 2, in this case, the top surface of the discharge block 30 and the waveguide
The distance L from the inner surface of the top wall 110 is adjustable. For example, when assembling or using the device,
The distance L is adjusted by moving the waveguide 110 or the discharge block 30 in the vertical direction by means (not shown) for moving the waveguide 110 or the discharge block 30 in the vertical direction. In FIG. 2, other parts, devices, and the like that are the same as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted.

In FIG. 2, the impedance L of the microwave can be matched by adjusting the interval L according to the shape of the space 120, that is, the shape that is enlarged from the connection portion of the waveguide 111 and then reduced by the microwave transmission window 40. , The reflected wave of the microwave from the load such as the plasma can be made zero. It is considered that the plasma density at this time is several times higher than that using a conventional hemispherical discharge tube, as shown in FIG. This is because the reflected wave of the microwave can be reduced to zero, so that the microwave is efficiently absorbed by the plasma.

FIG. 3 shows an output voltage at a time when a high-frequency power source having a constant power characteristic is applied to the sample table 61 in order to easily compare the magnitude of the plasma density.
The relationship between the present embodiment (A) and the prior art (B) is shown by comparing the relationship between the present invention and the output voltage (E). FIG. 3 shows that the smaller the output voltage, the lower the discharge impedance, that is, the higher the plasma density.

Therefore, in the present embodiment, the following effects can be obtained in addition to the effects of the above-described one embodiment.

(1) Since the plasma density is high, the etching processing speed can be greatly improved.

(2) Since the plasma density is high, the acceleration energy of ions with respect to the sample can be kept low, and etching processing with low damage can be performed.

It is desirable that the distance L between the top surface of the discharge block 30 and the inner surface of the top wall of the waveguide 110 be adjusted depending on the processing conditions such as the type of gas and the processing pressure. The device may be set and the device may be designed at the set interval L to manufacture the device.

 A third embodiment of the present invention will be described with reference to FIG.

FIG. 4 is a vertical sectional view showing a main part of a microwave plasma etching apparatus according to a third embodiment of the present invention.

FIG. 4 differs from FIG. 1 showing an embodiment of the present invention in that the waveguide 110 'is a waveguide that is expanded in a tapered shape, and the outer peripheral side surface of the discharge block 30' is a waveguide. The point is that it is tapered along the inner peripheral surface shape of the tube 110 '(however, the shape of the inner diameter portion of the cylinder is the same as in FIG. 1). The waveguide 110 ′ has a shape that is tapered from the connection end of the waveguide 111 toward the discharge block 30 ′. The air-core coil 140 'arranged at the upper stage has a smaller inner diameter than the air-core coil 141 arranged at the lower stage and has a larger number of coil turns. (Strong and gradually weakens toward the vacuum vessel 10). In FIG. 4, other parts, devices and the like that are the same as those in FIG.

In this embodiment, the following effects can be obtained in addition to the effects of the above-described embodiment.

(1) By making the shape of the waveguide having the discharge block inside tapered, the number of coil turns of the air-core coil arranged in the upper stage can be increased and the coil power supply (not shown) for generating the maximum magnetic field can be reduced. .

 A fourth embodiment of the present invention will be described with reference to FIG.

FIG. 5 is a vertical sectional view showing a main part of a microwave plasma etching apparatus according to a fourth embodiment of the present invention.

FIG. 5 differs from FIG. 1 showing an embodiment of the present invention in that an air-cored coil 142 for applying a correction magnetic field is mounted on a sample stage shaft 60 on the opposite side of the sample mounting surface of the sample stage 61. It is a point. The air-core coil 142 corrects a magnetic field near the surface to be processed of the sample 90 generated by the air-core coils 140 and 141 that apply a magnetic field into the discharge block 30. In FIG. 5,
In addition, the same components, devices, and the like as those in FIG.

In FIG. 5, when the direction of the magnetic flux by the air-core coils 140 and 141 is directed upward from the figure, and the direction of the magnetic flux of the air-core coil 142 is directed upward in the figure, the resultant magnetic field near the surface of the sample 90 to be processed is The direction is directed to the outer peripheral direction of the surface of the sample 90 to be processed, and if the direction of the magnetic flux of the air-core coil 142 is turned downward, the combined magnetic field tends to gather at the center of the surface of the sample 90 to be processed. The generated plasma has the property of easily diffusing in the flow direction of the magnetic flux. Therefore, by adjusting the direction and strength of the correction magnetic field, the plasma density and the diffusion state of the plasma can be corrected, and the processing speed of the sample can be corrected. , Uniformity can be corrected.

FIG. 6 shows a fifth embodiment of the present invention.
In the figure, the same parts, devices and the like as those in FIG.

In FIG. 6, reference numeral 142 'denotes an air-core coil for applying a correction magnetic field, and has the same operation as the air-core coil in the fourth embodiment.
It is effective. The air-core coil 142 'is
The sample is provided outside the vacuum vessel 10 on the opposite side of the sample setting surface, that is, in the atmosphere. Therefore, compared to the air-core coil of the fourth embodiment, the coil has superior characteristics in terms of heat dissipation, vacuum sealing, and maintenance.

FIG. 7 shows a sixth embodiment of the present invention.
In the figure, the same parts, devices and the like as those in FIG.

In FIG. 7, reference numeral 150 denotes a circular polarization conversion element,
And the waveguide 111. That is, one end of the circular polarization conversion element 150 is connected to the exit end of the waveguide 111,
The other end is connected to the waveguide 110.

In FIG. 7, a microwave (TE ₁₁ mode) converted into a circular waveguide mode by a rectangular / circular right angle conversion waveguide 111 is shown.
Is converted from linearly polarized light to circularly polarized light by the circular polarization conversion element 150, propagated to the next-stage waveguide 110, and further propagated into the discharge block 30 through the microwave transmission window 40.

In the present embodiment, in addition to the effects of the above-described embodiment, by using the circular polarization conversion element, the plasma generation density in the discharge block can be improved several times as compared with that of the above-described embodiment. Thus, there is an effect that the processing speed of the sample can be further improved.

As a measure for further improving the plasma density, in the above-described sixth embodiment, an example in which circularly polarized waves are used has been described. Alternatively, for example, pulse discharge of a magnetron is also effective.

In the above embodiment, application to a magnetic field type microwave plasma etching apparatus has been described as an example. In addition, a magnetic field type microwave CVD apparatus, and a non-magnetic type microwave plasma etching apparatus are also described. It goes without saying that the present invention can be similarly applied to an etching apparatus (including an ashing apparatus) and a CVD apparatus. As described above, when the present invention is applied to the microwave CVD apparatus, the uniformity of film formation is improved, and the film formation speed can be improved.

[Effects of the Invention] According to the present invention, since microwaves are introduced into the plasma reaction chamber only from the portion formed by the microwave transmission window,
There is an effect that the uniformity of the plasma density distribution corresponding to the surface to be processed of the sample is greatly improved, and the uniformity of the processing on the surface to be processed of the sample to be processed using this is improved.
Further, since the microwave impedance matching space is provided above the microwave transmitting window, there is an effect that the reflected wave of the microwave can be made zero.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view showing a main part of a microwave plasma etching apparatus according to one embodiment of the present invention, and FIG. 2 is a vertical sectional view showing a main part of a microwave plasma etching apparatus according to a second embodiment of the present invention. FIG. 3 is a schematic diagram showing the relationship between power supply output power and output voltage, similarly showing a comparison with the prior art, and FIGS. 4 to 7 are microwaves according to the third to sixth embodiments of the present invention. FIG. 3 is a vertical cross-sectional configuration diagram of a main part of the plasma etching apparatus. 10 Vacuum container, 20 Vacuum pump, 30, 30 'Discharge block, 40 Microwave transmission window, 61 Sample base,
80 ... high frequency power supply, 90 ... sample, 101 ... processing gas source, 1
10-112,110 '... waveguide, 120 ... space, 130 ... magnetron, 140-142, 140', 142 '... air-core coil, 150
…… Circular polarization conversion element

Continued on the front page (72) Inventor, Seiichi Watanabe 502, Kandate-cho, Tsuchiura-shi, Ibaraki Pref., Machinery Research Laboratory, Hitachi, Ltd. References JP-A-2-16732 (JP, A) JP-A-2-17636 (JP, A)

Claims (1)

(57) [Claims] 1. A means for generating microwaves, a rectangular / circular right angle conversion waveguide for introducing microwaves from the microwave generating means into a vacuum vessel, and a sample stage for holding a sample in the vacuum vessel. And a gas supply hole for introducing a gas to bring the inside of the vacuum vessel into a plasma state, and a vacuum exhaust device for bringing the inside of the vacuum vessel to a desired vacuum pressure, comprising: The microwave transmission window is provided by providing a discharge block on the upper surface of the vacuum container that does not allow the microwave to pass through the vacuum container, and providing the microwave transmission window so as to hermetically seal a hollow portion provided with the discharge block. The microwave is transmitted to the vacuum vessel below from almost the entire surface of the vacuum vessel, and the impedance of the microwave is matched between the rectangular / circular right angle conversion waveguide and the microwave transmitting window. A height waveguide provided constituting a space having a dimension, microwave plasma processing apparatus inner diameter of the space for the impedance matching is equal to or greater than the diameter of the microwave transmitting window.