JPH0560648B2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is directed to plasma CVD (Chemical Vapor CVD).
A plasma vapor phase epitaxy device is used to form a thin film on the surface of a sample, which is a workpiece, using the deposition method, and low-temperature plasma is used to perform surface modification such as dry etching and plasma oxidation on the sample surface. The present invention relates to a plasma processing apparatus for

Conventional technology The plasma CVD method holds a sample in a vacuum container,
While supplying a compound gas containing the constituent elements of the thin film to be formed, a thin film is formed on the sample surface by exciting the compound gas with high frequency energy and placing the sample surface in the low-temperature plasma atmosphere. This is a method of forming (depositing). This method utilizes the activity of low-temperature plasma, so
It is characterized by the ability to form thin films at temperatures as low as 400°C.

The challenges in forming thin films using plasma CVD are:
These problems include controlling the quality and thickness distribution of the formed thin film, as well as film defects such as pinholes and particle adhesion. Another issue in terms of production is improving the deposition rate.

Therefore, in order to uniformly form a high-quality plasma CVD film on the sample surface, it is necessary to devise process conditions such as the distribution and stability of the low-temperature plasma during thin film formation, the sample heating distribution, and the sample holding temperature. be.

An example of the above-mentioned conventional plasma vapor phase growth apparatus will be described below with reference to the drawings.

FIG. 10 shows a conventional plasma vapor phase growth apparatus. In FIG. 10, 1 is a vacuum container that can maintain a vacuum state, 2 is a sample on which a plasma CVD film is formed, 3 is a container that holds sample 2, and has a heater inside to heat the sample 2. 4 is a heater mounted inside the sample stage 3; 5 is an AC power source for supplying AC power to the heater 4; 6 is a sample table to which high frequency power of, for example, 50 KHz is supplied, and , 0.5 to 2.0 mm in diameter on the surface facing sample 2
The electrode 6a has a plurality of holes for supplying a compound gas containing the constituent elements of the thin film formed on the surface of the sample 2 into the vacuum vessel 1 through the holes; A plurality of holes, 6b is a supply port for supplying compound gas to the electrode 6 via a flow rate control device, 7 is a high frequency power source with a frequency of 50KHz, and 8 is a vacuum for reducing the pressure inside the vacuum container 1 to a degree of vacuum below atmospheric pressure. A vacuum pump for evacuation; 9 is a pipe for evacuation that airtightly connects the vacuum container 1 and the vacuum pump 8; 10 is a pipe for controlling the pressure inside the vacuum container 1 by varying the internal resistance of the pipe, that is, the effectiveness of the vacuum pump 8; This is a butterfly valve that variably controls the exhaust speed.

The operation of the plasma vapor deposition apparatus configured as described above will be described below.

First, the inside of the vacuum container 1 is pumped for 50m using the vacuum pump 8.
After evacuating to a vacuum level below Torr, sample 2
A compound gas containing the constituent elements of the thin film to be formed on the surface is introduced into the vacuum vessel 1 through the hole 6a while controlling the flow rate with a flow rate controller. Furthermore, the butterfly valve 10 is operated to control the inside of the vacuum vessel 1 to a pressure of 100 to 400 mTorr, which is the condition for forming a thin film. Further, the sample 2 is heated and controlled to a temperature of about 300°C by the sample stage 3. Next, apply a frequency of 50K to electrode 6.
By supplying high frequency power of Hz, the compound gas is excited, and the surface of the sample 2 is exposed to the plasma atmosphere, thereby forming a plasma CVD film on the surface of the sample 2.

Hereinafter, other conventional plasma vapor deposition apparatuses will be described with reference to the drawings.

FIG. 11 shows another conventional plasma vapor phase growth apparatus. In FIG. 11, 11 is a vacuum container, 12
is a sample, 13 is a sample stage, 14 is a heater mounted inside the sample stage 13, 15 is an AC power supply, 16 is an electrode to which high frequency power is supplied, 17 is a high frequency power supply,
18 is a vacuum pump, 19 is a pipe for vacuum evacuation,
20 is a butterfly valve for controlling the pressure inside the vacuum container, and 21 is a gas supply device for supplying a compound gas containing the constituent elements of the thin film into the vacuum container 11.

The operation of the plasma vapor phase growth apparatus configured as described above will be described below.

First, the inside of the vacuum container 11 is evacuated to a predetermined pressure using the vacuum pump 18, and then a compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 12 is introduced into the vacuum container 11 via the gas supply device 21. At the same time, the butterfly valve 20 is operated to control the pressure inside the vacuum vessel 11 to a pressure of 100 to 400 mTorr, which is the thin film forming condition. Also, the sample 12 is on the sample stage 1.
3, the heating is controlled to a temperature of about 300°C. Next, by supplying high-frequency power with a frequency of 50 KHz to the electrode 16, the compound gas is excited, and the surface of the sample 12 is exposed to the low-temperature plasma atmosphere, thereby forming a plasma CVD film on the surface of the sample 12. do.

Etching using low temperature plasma has recently become indispensable in semiconductor manufacturing processes. This is usually called a dry etching method.

In the dry etching method, a sample is held in a vacuum container and a compound gas containing halogen atoms is introduced.
This is a method of etching the surface of a sample by creating a predetermined pressure state, exciting the compound gas with high-frequency energy, and placing the sample in the low-temperature plasma atmosphere.

Hereinafter, an example of the conventional dry etching apparatus mentioned above will be explained with reference to the drawings.

FIG. 12 shows a conventional dry etching apparatus. In FIG. 12, 31 is a vacuum container capable of maintaining a vacuum state, 32 is a sample patterned with a resist mask, 32a is a resist mask, 3
3 is a sample stand that is grounded and holds the sample 32; 34 is supplied with high frequency power from 10 KHz to several 10 MHz; and has multiple holes with a diameter of 0.5 to 2 mm on the surface facing the sample 32. an electrode for supplying gas into the vacuum vessel 11 through the hole;
34a is a plurality of holes for introducing gas into the vacuum container 31, 34b is a supply port for supplying gas to the electrode 34 via a flow rate controller, 35 is a high frequency power source, and 36 is a pressure inside the vacuum container 31. Vacuum pump for evacuating to a degree of vacuum below atmospheric pressure, 37
38 is a vacuum exhaust pipe that airtightly connects the vacuum container 31 and the vacuum pump 36; 38 is the vacuum container 3;
This is a pressure control device for adjusting the pressure inside the vacuum pump 1 by varying the resistance inside the pipe, that is, by controlling the effective pumping speed of the vacuum pumping system.

The operation of the dry etching apparatus constructed as described above will be explained below.

First, the inside of the vacuum container 31 is pumped by the vacuum pump 36.
After evacuation to a vacuum level of 100 mTorr or less, a desired gas is introduced through the plurality of holes 34d of the electrode 34 by controlling the flow rate with a flow rate control device in order to generate a desired low-temperature plasma in the vacuum vessel 31. For example, when the material of the sample 32 is silicon nitride, the composition of this gas is mainly carbon tetrafluoride or sulfur hexafluoride. Furthermore, the pressure control device 3
8 to control the inside of the vacuum vessel 31 to a pressure of 100 to 500 mTorr, which is the dry etching condition. Next, by supplying high frequency power to the electrode 34, the introduced gas is excited and the surface of the sample 32 is exposed to the low temperature plasma atmosphere. Ions or radicals (atoms or molecules in an excited state) in this low-temperature plasma and the resist mask 3 of the sample 32
Desired dry etching is performed by contacting the portion 2a that is not covered, that is, the surface to be processed.

However, the above configuration has the following problems. In other words, in the case of the plasma vapor deposition apparatus shown in FIG.
Due to the pressure when forming the film, the flow rate of the compound gas, the amount of high-frequency power supplied to the electrode 6, etc., continuous or intermittent sparks are generated in the hole 6a of the electrode 6, and the compound gas is generated near the hole 6a. is intensively decomposed,
A large amount of porous film with low density adheres to the hole 6a portion. Since this film has weak adhesion to the electrode 6, it causes defects in the plasma CVD film formed on the surface of the sample 2. In addition, since the shape of the hole 6a, especially the diameter of the hole 6a, is changed by the attachment of the film, the supply condition of the compound gas into the vacuum container 1 is changed, and the conditions for forming the plasma CVD film on the surface of the sample 2 are changed, so that the film thickness is changed. The directional film quality changes, making it difficult to obtain a desired film with good reproducibility. Furthermore, when sparks are generated, the plasma becomes unstable, which significantly worsens the film quality and film thickness variation on the surface of the sample 2 of the plasma CVD film formed on the surface of the sample 2. Furthermore, when a spark occurs, high-frequency noise is added to measuring equipment and control equipment, which deteriorates the reliability of the equipment.

Further, in the case of the plasma vapor deposition apparatus shown in FIG. 11, as the thickness of the plasma CVD film on the surface of the sample 22 increases, the film also accumulates on the surface of the electrode 26 and increases. Sparks are generated on the surface of the electrode 26 when low-temperature plasma is generated due to the adhesion between the surface of the electrode 26 and these films and the material of these films. As a result, the film adhering to the surface of the electrode 26 is sputtered by the sparks, and depending on the conditions, it is blown off in chunks and adheres to the surface of the sample 22.
Defects are caused in the plasma CVD film formed on the surface of the sample 22. In addition, when sparks occur, the plasma becomes unstable, which worsens the film quality and film thickness variations on the surface of the plasma CVD film sample 22, and also has the disadvantage that high-frequency noise is added to measuring instruments, etc. was.

Furthermore, in the case of the dry etching apparatus shown in FIG. 12, due to the pressure, gas flow rate, high frequency power value, gas composition, etc. during dry etching, the hole 34a of the electrode 34 may be etched continuously or intermittently. Sparks are generated, the gas is intensively decomposed near the hole 34a, and the state of the low-temperature plasma becomes non-uniform, making it difficult to uniformly dry-etch the sample 32. Furthermore, the sparks significantly heat the resist mask 32a and damage the resist mask, making it difficult to dry-etch the sample 32 in a desired pattern. Furthermore, in the event of a spark, measuring equipment,
High frequency noise is added to control equipment, worsening the reliability of the equipment.

As described above, the conventional plasma vapor phase growth apparatus and dry etching apparatus have a problem in that spatters are generated near the electrodes 4, 14, and 34 to which high frequency power is supplied.

As a means to solve this problem, the present inventors applied high-frequency power and negative DC voltage to the electrodes.
It was confirmed and proposed that sparks can be prevented by simultaneously supplying the same to 14 and 34 (Japanese Patent Application No. 60-98366).

Problems to be Solved by the Invention However, in the method proposed by the present inventors, spark generation cannot be completely prevented if the value of the negative DC voltage is inappropriate, and conversely, Abnormal discharges other than the sparks shown in may occur, and there is no clear guideline for determining the value of the negative DC voltage, and the plasma generation conditions for these may vary depending on the pressure, gas flow rate, gas composition, and high-frequency power value. The problem was that it was necessary to determine the negative DC voltage by experiment each time.

In view of the above-mentioned problems, the present invention provides a plasma processing apparatus that can easily determine the negative DC voltage value to be supplied to the electrodes together with the high-frequency power, and can obtain stable low-temperature plasma. Another object of the present invention is to provide a plasma processing apparatus having a mechanism that can automatically control the value of the negative DC voltage during low-temperature plasma generation.

Means for Solving the Problems In order to solve the above problems, the plasma processing apparatus of the first aspect of the present invention includes an electrode that generates low-temperature plasma, and a high-frequency power that is supplied to the electrode via a matching circuit. a high-frequency power source for loading the electrodes with high-frequency power and a negative DC voltage through a filter circuit; The device is equipped with an ammeter for measuring the direct current flowing through the device. Moreover, the second invention of the present invention is provided with means for automatically controlling the negative DC voltage value according to the value of the DC current.

Effect The first invention of the present invention has the above configuration,
By applying an appropriate negative DC voltage to the electrode, electrons in the low-temperature plasma can be suppressed from entering the high-frequency power, and the electrons in the low-temperature plasma can be suppressed from entering the high-frequency power, particularly in the hole area of the electrode that supplies the gas, that is, locally below the pressure in the low-temperature plasma. Suppresses the inflow of electrons into high-pressure areas, prevents continuous or intermittent sparks in those areas, and charges electrons to the electrode surface to which high-frequency power is supplied, causing intermittent sparking on that surface during low-temperature plasma generation. In order to prevent sparks from occurring in the electrodes, it is possible to indirectly monitor the amount of electrons flowing into the electrode using a DC current measuring means, and easily determine a negative DC voltage value that will prevent the flow of electrons. can. Further, according to the second aspect of the present invention, the above-described configuration makes it possible to feed back the amount of monitored electrons and automatically control the negative DC voltage.

Embodiment A plasma vapor phase growth apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic cross-sectional view of a plasma vapor phase growth apparatus in a first embodiment of the present invention.

In FIG. 1, 41 is a vacuum container capable of maintaining a vacuum state, 42 is a sample as a workpiece on which a plasma CVD film is formed, and 43 holds sample 42 and has a heating device inside. A sample stand as a grounded workpiece holding means capable of heating the sample 42, 44 a heating device mounted inside the sample stand 43, 45 an AC power supply, and 46 a
A high frequency power of 50KHz and a negative DC voltage are supplied at the same time, and the surface facing the sample 42 has many holes with a diameter of 0.8 mm, and the vacuum vessel 4 is supplied through these holes.
1, an electrode made of aluminum capable of supplying a compound gas containing the constituent elements of the thin film formed on the surface of the sample 42 into the vacuum vessel 41; 46a, a plurality of holes for introducing the compound gas into the vacuum container 41; 46b; is a supply port for supplying compound gas to the electrode 45;
47 is a gas flow rate control device, 48 is a high frequency power supply with a frequency of 50 KHz, 49 is a vacuum pump as a vacuum evacuation means for reducing the pressure inside the vacuum container 41 to a degree of vacuum below atmospheric pressure, and 50 is the vacuum container 41 and the vacuum pump. 49 is an evacuation pipe for airtight connection; 51 is a pressure control device for controlling the pressure inside the vacuum container 41; and 52 is for supplying negative DC voltage to the electrode 46 via a filter circuit. 53 is a filter circuit for preventing high-frequency power from entering the DC power source 52, and 54 is a current as a current measuring means for measuring the DC current flowing between the filter circuit 53 and the DC power source 52. It is a total.

The operation of the plasma vapor phase growth apparatus configured as described above will be described below with reference to FIGS. 1, 2, 3, and 4.

First, the inside of the vacuum container 41 is evacuated to a vacuum level of 30 mTorr or less by the vacuum pump 49, and then
A compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 42, that is, a mixed gas of monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ), was mixed at gas flow rates of 13 SCCM, 31 SCCM, and 142 SCCM, respectively. Then, gas is introduced into the vacuum container 41 from the hole 46a of the electrode 46 via the electrode 46 from the gas flow rate control device 47, and the pressure inside the vacuum container 41 is maintained at 260 mTorr by operating the pressure control device 51. . Further, the sample 42 is heated and controlled to a temperature of 300° C. by the sample stage 43. Next, a DC power source 52 is connected to the electrode 46.
Then, apply a negative DC voltage of −200 to −250V,
In this state, by further supplying 0.33W/cm ² (100W) of high frequency power with a frequency of 50KHz,
A low-temperature plasma is generated in a space containing the sample 42. At this time, the value of the ammeter 54 is checked, and the DC power supply is operated so that the value approaches -0.02 mA, thereby correcting the negative DC voltage value. In our experiments, −
Corrected to 280V. By the above operation, the hole 46
Refractive index 1.998± without sparking in a
0.02, and a silicon nitride film with a film thickness distribution within ±3% could be formed. In addition, the number of particles of 0.3 μm or more adhering to the sample 42 was more than 10,000 per wafer in the case where sparks were generated, but it was 200 by preventing sparks.
We were able to significantly reduce the number of pieces to ~500 pieces/wafer.

FIGS. 2 and 3 show experimental results of whether sparks occur depending on the high frequency power value and the supply state of negative DC voltage, and the DC current value flowing through the ammeter 54 at that time. In Figure 2,
〇 indicates conditions under which no spark was generated, ×
The mark indicates the condition under which sparking occurred, and the value in parentheses is the value of the DC current flowing between the filter circuit 53 and the DC power supply 52. Further, in FIG. 3, the regions indicate conditions under which no spark was generated, and the regions indicate conditions under which sparks occurred. Further, the area and the mark △ in FIG. 2 are conditions under which abnormal discharge accompanied by overcurrent occurs. As can be understood from FIGS. 2 and 3, in order to obtain stable discharge, it is necessary to determine the negative DC voltage value depending on the high frequency power value. Here, the value of the ammeter 54 in a stable discharge state was -0.01 to -0.02 mA, independent of the high frequency power value. Therefore, the negative DC voltage value for obtaining a stable discharge state can be easily determined by applying a voltage such that the value of the ammeter 54 is -0.01 to -0.02 mA.

FIG. 4 shows the results of an experiment on the dependence of film deposition rate and refractive index on negative DC voltage values. Fourth
According to the figure, depending on the negative DC voltage, the plasma
It can be seen that the conditions for forming the CVD film do not change.

As described above, according to this embodiment, the vacuum container 41 that can maintain a vacuum state and the vacuum pump 49
, a pipe 50 , a sample stage 43 , and a heating device 44
The high frequency power is supplied, and the surface facing the sample 42 has at least one hole 46a, through which gas can be supplied into the vacuum container 41, and at least one hole 46a is provided in the surface facing the sample 42. An electrode 46 that generates low-temperature plasma, a high frequency power source 48, and a DC power source 52 are provided in a space containing the sample 42.
By providing a filter circuit 53 and an ammeter 54 for measuring the DC current, it is possible to easily determine the value of the negative DC voltage to be simultaneously supplied to the electrode 46 along with the high-frequency power, and to generate stable low-temperature plasma. can be obtained easily.

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

FIG. 5 is a schematic sectional view of a dry etching apparatus showing a second embodiment of the present invention.

In FIG. 5, 61 is a vacuum container capable of maintaining a vacuum state, 62 is a sample patterned with a resist mask, 62a is a resist mask, and 62b
is a silicon nitride film, 62c is a silicon substrate, 63
64 is a sample stand that is grounded, and 64 is supplied with high-frequency power and has a diameter on the surface facing the sample 62.
An electrode having a plurality of holes of 0.8 mm and supplying gas into the vacuum container 61 through the holes, 64a is a plurality of holes for introducing gas into the vacuum container 61, 64
b is a supply port for supplying gas to the electrode 64 via a flow rate control device, 65 is a high frequency power source with a frequency of 50 KHz, and 66 is a vacuum for evacuating the pressure inside the vacuum container 61 to a degree of vacuum below atmospheric pressure. pump, 67
68 is a vacuum exhaust pipe that airtightly connects the vacuum container 61 and the vacuum pump 66, and 68 is the vacuum container 6.
1 is a pressure control device for adjusting the pressure in the tube by making the resistance inside the pipe variable; 69 is a DC power supply for supplying negative DC voltage to the electrode 64 via a filter circuit; 70 is a DC power supply for supplying power of high frequency components; Filter to prevent passage in 69 directions, 7
Reference numeral 1 denotes an ammeter for measuring the DC current flowing between the filter 70 and the DC power supply 69.

The operation of the dry etching apparatus constructed as described above will be explained below with reference to FIGS. 5, 6, and 7.

First, the inside of the vacuum container 61 is pumped by the vacuum pump 66.
After evacuation to a vacuum level of 100mTorr or less, sulfur hexafluoride (SF ₆ ) gas is supplied to the electrode 6 from the supply port 64b at a flow rate of 240SCCM via a gas flow rate controller.
4 and the vacuum container 6 through the hole 64a of the electrode 64.
1, and the pressure inside the vacuum vessel 61 is maintained at 290 mTorr by operating the pressure control device 68. Next, apply high frequency power to the electrode 64 at 100W (0.33W/
cm ² ) and a negative DC voltage value of −100 V, a low-temperature plasma is generated in the space containing the sample 62. At this time, the value of the ammeter 71 is checked, and the DC power supply 69 is operated so that the value approaches -0.02 mA to -0.09 mA, thereby correcting the negative DC voltage value. In our experiment, it was corrected to -130V.
By the above operation, the silicon nitride film 64 is exposed through the resist mask 62a without generating sparks in the hole 64a and without fluctuation of discharge.
I was able to etch b. At this time, the etching rate of the silicon nitride film was 4000 Å/min, the etching variation was ±2.1%, and the etching rate of the resist was about 300 Å/min (negative resist).

Figures 6 and 7 show high frequency power value of 100W.
(0.33W/cm ² ) Ammeter 7: Whether or not there is a spark when changing the negative DC voltage value under a constant condition.
1 shows the results of experimentally determining the value of the DC current flowing through the circuit. In FIGS. 6 and 7, the x marks and regions indicate conditions under which spark or discharge fluctuations occur, and the open circles and regions indicate conditions under which stable low-temperature plasma occurs. Further, the △ mark and the area indicate conditions in which numerous minute sparks (abnormal discharges) are generated on the surface of the electrode 64. Therefore, in order to generate stable low-temperature plasma, the negative DC voltage value may be determined so that the value of the ammeter 71 is in the range of -0.02 to -0.15 mA. Furthermore, an experiment was conducted to determine the dependence between the etching rate and the negative DC voltage value, but it was found that the etching rate did not change due to the negative DC voltage.

As described above, according to this embodiment, the vacuum container 61 that can maintain a vacuum state, the vacuum pump 66,
Pipe 67, pressure control device 68, and sample stage 63
, an electrode 64 , a high frequency power source 65 , and a DC power source 6
By providing the filter 9, the filter 70, and the ammeter 71, it is possible to determine the negative DC voltage value to be simultaneously supplied to the electrode 64 together with the high-frequency power, and it is possible to easily obtain stable low-temperature plasma.

Next, a third embodiment of the present invention will be described with reference to the drawings.

FIG. 8 is a schematic cross-sectional view of a plasma vapor phase growth apparatus showing a third embodiment of the present invention.

In FIG. 8, 81 is a vacuum container, 82 is a sample, 83 is a sample stage, 84 is a heater mounted inside the sample stage 83, 85 is an AC power supply, and 86 is supplied with high frequency power and negative DC voltage. Electrodes made of aluminum, 87 a high frequency power supply with a frequency of 50 KHz, 88 a vacuum pump, 89 a vacuum exhaust pipe, 90 a pressure control device, 91 a gas supply device,
92 is a DC power supply that outputs a negative DC voltage; 93 is a filter circuit that prevents high frequency power components from entering the DC power supply 92; and 94 is a filter circuit 9.
a sensor 95 as a current measuring means for detecting the DC current flowing between 3 and the DC power supply 92;
is a feedback circuit that compares the current value detected by the sensor 94 with a set value and manipulates the DC voltage value output from the DC power supply 92 so that it approaches the set value.

The operation of the plasma vapor phase growth apparatus configured as described above will be described below.

First, after evacuating the inside of the vacuum container 81 to a vacuum level of 30 mTorr or less using the vacuum pump 88,
A compound gas containing the constituent elements of the thin film to be formed on the surface of the sample 82, that is, a mixed gas of monosilane (SiH ₄ ), ammonia (NH ₃ ), and nitrogen (N ₂ ), was applied to each sample.
While introducing gas into the vacuum container 81 from the gas supply device 91 at flow rates of 10 SCCM, 31 SCCM, and 80 SCCM, the pressure control device 90 is operated to maintain the pressure inside the vacuum container 81 at 300 mTorr. Next, a negative DC voltage of -200 to -250V is applied to the electrode 86 from the DC power supply 92, and in this state, a voltage of 50K is applied to the electrode 86.
A low temperature plasma is generated in the space containing the sample 82 by supplying Hz high frequency power of 0.33 W/cm ² (100 W). At the same time as generating low temperature plasma, the sensor 94 and feedback circuit 95 are activated. At this time, by setting the current value of the feedback circuit 95 to -0.02mA,
The output voltage of the DC power supply 92 is automatically corrected.
Operates in the range of 280 to -320V. Through the above operations, stable low-temperature plasma can be obtained, and the refractive index
2000±0.03, and a silicon nitride film with a film thickness distribution within ±4% could be formed. Also sample 8
The number of particles of 0.3μm or more attached to 2 is
200 to 500 pieces/wafer.

Figure 9 shows the results of the film when the negative DC voltage value is automatically controlled using the feedback circuit 95 and an appropriate DC voltage is applied, when no negative DC voltage is applied, or when an inappropriate DC voltage is applied. An experiment was conducted to compare the number of particles attached to a wafer after deposition. Particle measurements were performed using a commercially available laser surface inspection device. 1st
The experimental point indicated by arrow A in FIG. Here, the number of particles represents the total number of particles of 0.3 μm or more.

As described above, according to this embodiment, the sensor 94
By providing a means for controlling the output value of the DC power supply 92 using the feedback circuit 95 based on the DC current value detected by the above, stable low-temperature plasma can be easily obtained.

Effects of the Invention As described above, the first aspect of the present invention provides an electrode that supplies high-frequency power to generate low-temperature plasma.
By providing a DC power source for loading a negative DC voltage through a filter circuit, and further having a current measuring means for measuring a DC current flowing between the DC power source and the filter circuit, a predetermined appropriate voltage can be applied. The DC voltage value to obtain the DC current value can be easily determined, and stable low-temperature plasma can be generated without generating sparks, resulting in good plasma processing. have

In addition to the configuration of the first invention, the second invention of the present invention provides a current It becomes possible to automatically control the DC voltage value by feeding back the current value monitored by the measuring means, and has the effect that more stable plasma can be generated.

[Brief explanation of drawings]

Fig. 1 is a schematic cross-sectional view of a plasma vapor phase growth apparatus according to an embodiment of the present invention, and Figs. 2 and 3 show whether or not sparks are generated due to high frequency power values and negative DC voltage values, and the DC current value at that time. FIG. 4 is a diagram showing the experimental results of examining the dependence of film deposition rate and refractive index on negative DC voltage values. FIG. A schematic cross-sectional view of the etching device, FIGS. 6 and 7 are diagrams showing the results of an experiment to investigate the occurrence of sparks depending on the DC voltage value and the DC current value at that time. FIG. Figure 9 is a schematic cross-sectional view of the plasma vapor deposition apparatus, and the number of particles was investigated when an appropriate negative DC voltage was applied, when no negative DC voltage was applied, or when an inappropriate negative DC voltage was applied. 10 and 11 are schematic cross-sectional views of a conventional plasma vapor phase growth apparatus, and FIG. 12 is a schematic cross-sectional view of a conventional dry etching apparatus. 41... Vacuum container, 44... Sample stand, 46...
Electrode, 47...Gas flow control device, 48...High frequency power supply, 49...Vacuum pump, 51...Pressure control device, 52...DC power supply, 53...Filter circuit, 54...Ammeter, 61... Vacuum container, 63...
...sample stage, 64...electrode, 65...high frequency power supply,
66... Vacuum pump, 68... Pressure control device, 6
9...DC power supply, 70...Filter, 71...
Ammeter, 81... Vacuum container, 83... Sample stand, 8
6... Electrode, 87... High frequency power supply, 88... Vacuum pump, 90... Pressure control device, 91... Gas supply device, 92... DC power supply, 93... Filter circuit, 94... Sensor, 95... ...feedback circuit.

Claims (1)

[Claims] 1. A vacuum container capable of maintaining a vacuum state, a vacuum evacuation means for creating a reduced pressure atmosphere inside the vacuum container,
A pressure control means for bringing the pressure in the vacuum container to a predetermined value, a gas supply means for introducing gas into the vacuum container, a workpiece holding means for holding the workpiece, and a a high-frequency power source for supplying high-frequency power to the electrode via a matching circuit; A DC power source for loading a negative DC voltage along with electric power through a filter circuit, and a DC power source disposed between the DC power source and the filter circuit to measure the DC current flowing in the section between the DC power source and the filter circuit. A plasma processing apparatus comprising current measuring means. 2. A vacuum container capable of maintaining a vacuum state, and evacuation means for creating a reduced pressure atmosphere inside the vacuum container,
A pressure control means for bringing the pressure in the vacuum container to a predetermined value, a gas supply means for introducing gas into the vacuum container, a workpiece holding means for holding the workpiece, and a a high-frequency power source for supplying high-frequency power to the electrode via a matching circuit; In addition, a DC power supply for loading a negative DC voltage through the filter circuit, and a current for measuring the DC current flowing in the section between the DC power supply and the filter circuit, which is arranged at least between the DC power supply and the filter circuit. A plasma processing apparatus comprising a measuring means and a DC voltage control means for controlling a negative DC voltage value from a DC power supply according to the value of the current measured by the current measuring means.