JP2012104382A - Plasma treatment apparatus, plasma treatment method, and plasma treatment bias voltage determination method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma treatment apparatus capable of forming an appropriate ion energy distribution according to plasma treatment, as well as a plasma treatment method and a plasma treatment bias voltage determination method.SOLUTION: The plasma treatment apparatus includes a vacuum chamber 11 having a placement stand 2 disposed inside the chamber and a DC pulse voltage generation unit 3 which applies a bias voltage, or a DC pulse voltage, to the placement stand 2. The DC pulse voltage generation unit 3 takes advantage of the fact that a peak in an ion energy distribution diagram consisting of ion energy values on a horizontal axis and ion frequencies on a vertical axis appears in correspondence to an amplitude value of the DC pulse voltage as it generates plural kinds of DC pulse voltages differing in the amplitude value from each other, whereby adjustment is made until an ion energy distribution pattern which forms an overlapping area in the distribution diagram in which peaks adjacent to each other overlap one on top of another becomes an appropriate pattern for plasma treatment.

Description

  The present invention relates to a plasma processing apparatus that performs plasma processing by applying a bias voltage to a substrate, a plasma processing method, and a method for determining the bias voltage.

  For example, a parallel plate type plasma apparatus can be cited as an apparatus for performing plasma processing, which is a manufacturing process of a semiconductor device. This device applies high-frequency power between parallel plates in a vacuum chamber to excite the processing gas (plasmaization). In order to improve film quality during film formation and to achieve verticality during etching. A negative voltage bias is applied to the mounting table, and positive ions in the plasma are drawn into a semiconductor wafer (hereinafter referred to as “wafer”) which is a substrate on the mounting table.

  By the way, in Patent Document 1, although the substrate incident energy of ions periodically varies as the bias potential varies periodically, there is a delay in tracking the potential due to the ion mass, so the ion tracking voltage is used for bias. It is described that the time fluctuates with an amplitude smaller than the amplitude of the high-frequency voltage. Also, it is described that when an ion energy distribution diagram is created with ion energy on the horizontal axis and ion frequency on the vertical axis, an ion energy distribution having two sharp peaks as shown in FIG. 10 is obtained. Yes.

  On the other hand, in order to improve the crystallinity of the thin film at the time of film formation and the shape defect at the time of etching, there is an appropriate ion energy distribution depending on the type of plasma treatment. For example, as shown in FIG. 11, a low energy band (pattern A) of 15 eV or less is used in the process of forming a silicon film for solar cells, and an energy band (pattern B) of 100 eV or less is used in etching a resist film. In the process, for example, it is preferable to form an ion energy distribution in which energy bands (pattern C) around 300 eV to 400 eV exist. In the multilayer film etching process, as shown in FIG. 12, there is a low energy band (pattern D) for improving etching selectivity and a high energy band (pattern E) for improving the etching shape. It is considered preferable to form an ion energy distribution.

  However, these ion energy distributions require a more precise control of the distribution shape, and it is difficult to form an appropriate ion energy distribution according to the plasma processing by the conventional method.

  By the way, Patent Document 1 describes a technique of applying a negative DC pulse voltage so as to be superimposed on a high frequency voltage on a lower electrode. In this technique, since the bias potential is controlled by combining the high frequency voltage and the negative DC pulse voltage, the peak position of the ion energy distribution can be adjusted. However, the present inventor aims to establish a method capable of forming an ion energy distribution having an arbitrary shape.

JP 2009-187975 A

  The present invention has been made under such circumstances, and it is an object of the present invention to provide a technique capable of forming an appropriate ion energy distribution in accordance with plasma processing.

Therefore, the plasma processing apparatus of the present invention is
A vacuum chamber in which a placement unit on which a substrate is placed is disposed;
A gas supply unit for supplying a processing gas for plasma processing into the vacuum chamber;
A plasma generation unit that supplies power to the processing gas to convert the processing gas into plasma;
A bias power supply unit that applies a bias voltage that is a DC pulse voltage to the mounting unit;
The bias power supply unit
In the ion energy distribution diagram in which the ion energy value is taken on the horizontal axis and the ion frequency is taken on the vertical axis, the amplitude values are expressed by utilizing the fact that a peak appears corresponding to the amplitude value of the DC pulse voltage. Are generated so that the ion energy distribution pattern in which the peaks adjacent to each other in the distribution map overlap to form an overlapping region becomes an appropriate pattern for plasma processing. It is characterized by.

Moreover, the plasma processing method of the present invention comprises:
Placing the substrate on the placement portion in the vacuum chamber;
Supplying a processing gas for plasma processing into the vacuum chamber;
Supplying electric power to the processing gas to turn the processing gas into plasma;
Applying a bias voltage, which is a DC pulse voltage, to the mounting portion,
The step of applying the bias voltage is as follows:
In the ion energy distribution diagram in which the ion energy value is taken on the horizontal axis and the ion frequency is taken on the vertical axis, the amplitude values are expressed by utilizing the fact that a peak appears corresponding to the amplitude value of the DC pulse voltage. The bias voltage is generated in such a manner that a plurality of different DC pulse voltages are generated so that an ion energy distribution pattern in which the adjacent peaks in the distribution diagram overlap to form an overlap region becomes a pattern suitable for plasma processing. It is a step of applying a voltage.

Furthermore, the plasma processing bias voltage determination method of the present invention provides a processing gas supplied by supplying power to the processing gas supplied in the vacuum chamber in a state where the substrate is mounted on the mounting portion in the vacuum chamber. Plasma is generated by generating a plasma, and a bias voltage, which is a DC pulse voltage, is applied to the substrate by the bias power supply unit in order to attract ions in the plasma to the substrate placed on the placement unit. Perform plasma treatment,
The bias power supply unit
In the ion energy distribution diagram in which the ion energy value is taken on the horizontal axis and the ion frequency is taken on the vertical axis, the amplitude values are expressed by utilizing the fact that a peak appears corresponding to the amplitude value of the DC pulse voltage. To generate a plurality of different types of DC pulse voltages, thereby adjusting an ion energy distribution pattern in which peaks adjacent to each other in the distribution map overlap to form an overlapping region,
Various application patterns of the bias voltage are set, the plasma treatment is performed for each setting, and the bias voltage is applied so that a good plasma treatment can be obtained based on the plasma treatment result of the substrate after each plasma treatment. It is characterized by obtaining a pattern.

  According to the present invention, in the bias power supply unit, a plurality of DC pulse voltages having different amplitude values are generated, or the amplitude values are changed stepwise in one DC pulse voltage. An ion energy distribution pattern in which overlapping peaks are formed by overlapping peaks adjacent to each other can be formed in a shape suitable for plasma processing.

It is sectional drawing which shows embodiment of the plasma processing apparatus which concerns on this invention. It is a characteristic view which shows an example of ion energy distribution. It is a characteristic view which shows an example of ion energy distribution. It is a characteristic view which shows an example of ion energy distribution. It is a characteristic view which shows an example of ion energy distribution. It is a characteristic view which shows an example of ion energy distribution. It is sectional drawing which shows embodiment of the experimental apparatus used with the bias voltage determination method which concerns on this invention. It is a flowchart which shows the 1st process of the bias voltage determination method which concerns on this invention. It is a flowchart which shows the 2nd process of the bias voltage determination method which concerns on this invention. It is a characteristic view which shows an example of the conventional ion energy distribution. It is a characteristic view which shows an example of ion energy distribution. It is a characteristic view which shows an example of ion energy distribution.

  Hereinafter, the configuration of a plasma etching apparatus 1 which is an embodiment of the plasma processing apparatus of the present invention will be described with reference to FIG. In FIG. 1, 11 is a cylindrical vacuum chamber, and the inner surface thereof is insulated by, for example, alumite coating. An exhaust device 12 including a vacuum pump and a pressure adjusting unit is connected to an exhaust port 12 provided on the bottom surface of the vacuum chamber 11 via an exhaust path 14, and is based on a control signal from a control unit 100 described later. The inside of the vacuum chamber 11 is evacuated to maintain a predetermined degree of vacuum. In FIG. 1, 15 is a carry-in port, and 16 is a gate valve for opening and closing the carry-in port.

  In the center of the bottom surface in the vacuum chamber 11, a mounting table 2 for mounting a substrate, for example, a wafer W, is provided. The mounting table 2 is configured to have a circular planar shape, for example. A lower electrode 21 is embedded in the mounting table 2, and a DC pulse generator 3 is connected to the lower electrode 21. The DC pulse generation unit 3 corresponds to a bias power supply unit that applies a bias voltage, for example, a negative DC pulse voltage of 1 MHz to the mounting unit 2.

  The DC pulse generator 3 includes, for example, a pulse oscillator, a pulse amplifier, and a low-pass filter, and is configured to continuously change the amplitude value and pulse width of the DC pulse voltage. In the present embodiment, for example, as shown in FIG. 2A, a waveform pattern is set in which a plurality of types, for example, four rectangular pulse voltage waveforms whose amplitude values are different from each other and increase stepwise are used as a cycle unit. In the figure, reference numeral 22 denotes a focus ring for focusing plasma on the wafer W.

  A gas shower head 4 is provided on the upper side in the vacuum chamber 11 so as to face the mounting table 2. The gas shower head 4 forms a gas supply unit that supplies a processing gas for plasma processing into the vacuum chamber 11. In this example, the gas shower head 4 has a circular planar shape and is made of ceramics such as quartz. The gas shower head 4 is configured to include a space 41 into which a processing gas is supplied, and a plurality of gas supply holes 42 for distributing and supplying the gas into the vacuum chamber 11 are provided on the lower surface of the gas shower head 4. It is formed so as to communicate with. A gas introduction path 43 is provided in the center of the upper surface of the gas shower head 4, and the other end of the gas introduction path 43 is supplied with a processing gas via a gas supply system 45 including a valve V 1, a flow rate controller 44 and the like. 46. When several types of processing gases are supplied, another introduction path (not shown) is connected to the gas shower head 4. In the figure, reference numeral 47 denotes a cover body made of an insulator.

  A high frequency power supply unit 5 is connected to the gas shower head 4. The high-frequency power supply unit 5 supplies high-frequency power for generating plasma, and is configured to apply a high frequency of 100 MHz, for example. In this example, the high-frequency power supply unit 5 corresponds to a plasma generation unit that supplies power to the processing gas and converts the processing gas into plasma.

The plasma etching apparatus is provided with a control unit 100 including, for example, a computer. The control unit 100 includes a data processing unit including a program, a memory, and a CPU. The program includes various units of the plasma etching apparatus such as the high frequency power supply unit 5, the DC pulse generation unit 3, and the exhaust device 13. A command (each step) is incorporated so that a predetermined plasma process, for example, an etching process is performed on the wafer W by sending a control signal to the gas supply system 45 or the like and advancing each step described later. This program is stored in a storage unit such as a computer storage medium such as a flexible disk, a compact disk, a hard disk, or an MO (magneto-optical disk) and installed in the control unit 100. Subsequently, the plasma etching apparatus 1 executes the program. A plasma etching method will be described. First, the gate valve 16 is opened and a wafer W is loaded into the vacuum chamber 11 by a transfer mechanism (not shown) and placed on the mounting table 2. After the transfer mechanism is retracted, the gate valve 16 is closed.

  Then, the exhaust chamber 13 exhausts the vacuum chamber 11 through the exhaust path 14 to maintain the inside of the vacuum chamber 11 at a predetermined pressure, and at the same time, an etching gas that is a processing gas from the gas shower head 4 into the vacuum chamber 11. Is introduced. On the other hand, the high frequency power supply unit 5 and the DC pulse generation unit 3 are simultaneously turned on, for example. Thus, a negative DC pulse voltage of 1 MHz, for example, is applied to the lower electrode 21, and a high frequency voltage for generating plasma of 100 MHz, for example, is applied from the high frequency power supply unit 5.

When the high-frequency voltage is applied in this way, high-frequency energy is generated, whereby the processing gas such as CF ₄ gas is activated, and plasma is formed below the gas shower head 4. Here, when the exhaust is performed below the vacuum chamber 11, the plasma is lowered, and various ions constituting the plasma are drawn into the wafer W by the bias voltage applied to the lower electrode 21, and anisotropic etching is performed. Is done.

  Here, the ion energy distribution of plasma will be described. This ion energy distribution is a characteristic diagram in which the horizontal axis represents the energy value of ions in the plasma and the vertical axis represents the frequency of ions. First, since a high frequency of 100 MHz is applied from the high frequency power supply unit 5 for generating plasma, when the ion energy distribution based on this high frequency application is obtained, as shown by a one-dot chain line in FIG. As the region, for example, a band-shaped region at 15 eV or less is obtained.

  On the other hand, since a negative DC pulse voltage of 1 MHz is applied to the lower electrode 21 from the DC pulse generator 3, the ion energy obtained thereby is larger than the ion energy resulting from the high frequency for plasma generation.

  Here, the plasma processing apparatus according to this embodiment is configured to obtain an ion energy distribution suitable for the intended plasma processing by devising the application of the bias voltage. For example, when etching a resist film, the bias voltage is set so that the ion energy distribution of the pattern B in FIG. 11 described above can be obtained.

  This setting will be described in detail below. When a negative DC pulse voltage is applied to the lower electrode 21, an ion energy distribution having a peak corresponding to the amplitude value of the DC pulse voltage is formed. For example, as shown in FIG. 4A, when pulses having an amplitude value of negative voltage −Va and negative voltage −Vb are alternately applied to the lower electrode 21, the negative voltage −Va is obtained as shown in FIG. An ion energy distribution having a peak Pa caused by and a peak Pb caused by the negative voltage −Vb is formed.

  Also, as shown in FIG. 2 (a), when four pulse voltage waveforms whose amplitude values are different from each other and increase stepwise are set as waveform units, four waveform patterns are set as shown in FIG. 2 (b). An ion energy distribution is formed such that peaks based on the bias voltage overlap each other. At this time, the waveform patterns using the pulse voltage waveforms whose amplitude values are different from each other and change stepwise include the patterns shown in FIG. 3A and FIG. 3B.

  Therefore, by adjusting the amplitude value of each pulse, the peak position of ion energy caused by the bias voltage can be adjusted. Then, by adjusting the number of pulses included in the one period and the amplitude value of each pulse, peaks adjacent to each other in the ion energy distribution diagram overlap to form an overlapping region, and as a result, the target ion energy An ion energy distribution having a band is obtained.

  The target ion energy distribution is an ion energy distribution suitable for plasma processing, and suitable for plasma processing is that, for example, in the case of an etching process, the verticality of the wall portion of the recess is good. In the case of a film process, a thin film with good film quality, for example, a silicon film for solar cells, can produce a thin film with a low defect density. The ion energy distribution suitable for plasma processing is determined by evaluating the process results by performing various processes using a device that performs the actual process and changing the method of generating the pulse voltage, which is a bias voltage. However, as will be described later, it may be determined in the same manner using an experimental machine.

  Thus, after performing plasma processing with plasma having an appropriate ion energy distribution, in this example, etching processing is performed, the high-frequency power supply unit 5 and the DC pulse generation unit 3 are turned off, and the supply of the processing gas is stopped, so that the inside of the vacuum chamber 11 The remaining gas is exhausted. Then, the gate valve 16 is opened, and the wafer W is unloaded from the vacuum chamber 11 by the transfer mechanism.

  According to the above-described embodiment, the bias voltages that are a plurality of types of DC pulse voltages having different amplitude values are generated by the DC pulse generator 3, so that in the ion energy distribution based on the bias voltage, An overlapping region is formed in which adjacent peaks overlap each other. For this reason, by adjusting the bias power supply unit 3 that is a DC pulse generation unit, that is, by adjusting the application pattern of the DC pulse, the magnitude of the ion energy spreads in a band shape, and an appropriate ion energy distribution according to the plasma processing A pattern can be formed.

  Furthermore, in the above-described embodiment, an overlap region can be formed in a low energy band that cannot be formed with a bias voltage in the ion energy distribution by applying a high frequency for plasma generation. Accordingly, when a peak P1 caused by the high frequency for plasma generation indicated by the one-dot chain line in FIG. 5A and a peak P2 based on the bias voltage indicated by the dotted line in FIG. 5A are formed, between these peaks P1 and P2. By overlapping a large number of peaks due to the bias voltage so as to fill the energy band, a band-shaped overlapping region can be formed in the low energy band as shown in FIG.

  As described above, by adjusting the bias power supply unit, an overlapping region can be formed at 100 eV or less, so that an ion energy distribution suitable for a resist film etching process can be formed. For this reason, the etching process of a resist film with high etching selectivity and favorable etching shape can be performed.

  For example, when an ion energy distribution having an overlapping region in the vicinity of 300 eV to 400 eV is formed, the organic film can be satisfactorily etched. Furthermore, an ion energy distribution having an overlapping region in the low energy band and the high energy band can also be formed, and in this case, the multilayer film can be satisfactorily etched.

Furthermore, a plasma film forming process can also be performed using the above-described plasma processing apparatus. For example, when a silicon film for a solar cell is formed using SiH ₄ gas and H ₂ gas as process gases, By forming an ion energy distribution having an overlapping region in a low energy band of 15 eV or less, a silicon film having a low defect density can be formed.

  Next, another embodiment of the present invention will be described with reference to FIG. In this example, the negative DC pulse voltage is generated so that the amplitude value of one pulse voltage changes stepwise, and in the step of applying the bias voltage, a plurality of pulse voltages having different amplitude values are used. Instead of applying, a pulse voltage whose amplitude value changes stepwise in one pulse voltage is applied. Here, the fact that one pulse voltage is generated so that the amplitude value changes stepwise is, for example, a waveform pattern as shown in FIG. 6A. Even in this case, in the ion energy distribution, Overlapping areas are formed by overlapping peaks caused by amplitude values.

  Further, when generating a plurality of types of pulse voltages having different amplitude values, as shown in FIG. 6B, for example, two pulses having the same amplitude value form one set, and the amplitude values are mutually different. Different sets of pulses may be used.

  The present invention generates a plurality of types of pulse voltages having different amplitude values from the bias power supply unit as described above, or generates a pulse voltage so that the amplitude value of one pulse voltage changes stepwise. However, the number of types of the plurality of types of pulses is determined by the width of the target ion energy band in the ion energy distribution.

  Next, an embodiment of the plasma processing bias voltage determination method of the present invention will be described. This method uses an experimental machine to obtain an ideal pattern of an ion energy distribution suitable for plasma processing, a first step of acquiring an ideal pattern of a DC pulse voltage waveform for obtaining the ion energy distribution, and actually a substrate. And a second step of finely adjusting a DC pulse voltage application pattern for obtaining an ideal pattern of the ion energy distribution using a plasma processing apparatus that performs plasma processing on the plasma. Note that in this embodiment, a case where a film formation process is performed as a plasma process is described as an example.

  First, the experimental machine 6 used in the first step will be described with reference to FIG. In FIG. 7, reference numeral 61 denotes a vacuum chamber of a wafer W which is a substrate, and the inner surface thereof is insulated by, for example, alumite coating. The vacuum chamber 61 is formed in a cylindrical shape, and a mounting portion 62 for the wafer W is detachably provided at the bottom. A DC pulse generator 3 is connected to the mounting unit 62, and the DC pulse generator 3 is configured in the same manner as that shown in FIG.

  A planar antenna 63 for generating plasma is provided on the upper side in the vacuum chamber 61 so as to face the wafer W, and a microwave of 2.45 GHz is applied thereto. Further, a processing gas source 65 is connected to the upper side of the vacuum chamber 61 via a processing gas supply path 64, and a vacuum exhaust means 67 is connected to the lower side of the vacuum chamber 61 via an exhaust path 66. Yes. Further, ion energy measuring means 7 is provided in the vacuum chamber 61. As this ion energy measuring means 7, for example, a quadrupole mass analyzer with an energy selection mechanism can be used.

  The first step will be described with reference to FIG. 8, taking as an example a case where an etching process is performed as a plasma process. First, the DC pulse generator 3 sets the application pattern of the DC pulse voltage so as to generate a plurality of types of pulse voltages having different amplitude values (step S1). Then, the wafer W to be deposited is placed on the placement unit 62, and the placement unit 62 is attached to the bottom of the vacuum chamber 61.

Then, evacuation is performed by the vacuum evacuation means 67, and the inside of the vacuum chamber 61 is maintained at a predetermined pressure, and a film forming gas, for example, SiH ₄ and H ₂ gas, which are processing gases, are introduced. On the other hand, the high-frequency power supply unit 5 and the DC pulse generation unit 3 are simultaneously turned on, for example, to apply a negative DC pulse voltage of 1 MHz to the wafer W, and for example, a microwave for generating plasma of 2.45 GHz is applied to the planar antenna 63. Apply. In this way, power is supplied to the processing gas, the processing gas is turned into plasma, and a predetermined silicon film forming process (plasma processing) is performed (step S2).

  On the other hand, in parallel with the film forming process, an ion energy distribution pattern is acquired by the ion energy measuring means 7 (step S3). Next, it is evaluated whether or not the characteristics of the film forming process are favorable for the wafer W subjected to the film forming process (step S4). In this example, the defect density is evaluated with respect to the film quality of the silicon film. When the plasma processing characteristics are good, the application pattern of the DC pulse voltage set by the DC pulse generator 3 is acquired as an ideal pattern, and the ion energy distribution pattern at this time is acquired as an ideal pattern ( Step S6). On the other hand, if the plasma processing characteristics are not good, the process returns to step S1, the application pattern of the DC pulse voltage is set again, and the subsequent steps are repeated.

  In the case where the plasma treatment is an etching treatment, whether or not the characteristics of the plasma treatment are good after introducing an etching gas as a treatment gas and actually performing the etching treatment on the wafer W in the experimental apparatus. Evaluates, for example, the etching rate and shape defects.

  Next, the second process will be described. The apparatus for performing the second step is an apparatus in which ion energy measuring means is provided in a plasma processing apparatus that actually performs plasma processing on a substrate.

  The second step will be described with reference to FIG. 9, taking as an example a case where a film forming process is performed as a plasma process. First, in the DC pulse generator 3, an ideal pattern of the waveform pattern of the DC pulse voltage obtained in the first step is set (step S11). Next, the wafer W to be deposited is mounted on the mounting table 2 in the vacuum chamber 11.

Then, evacuation is performed by the evacuation means 67 to maintain the inside of the vacuum chamber 11 at a predetermined pressure, and a film forming gas such as SiH ₄ gas or H ₂ gas as a processing gas is introduced from the gas shower head 4. On the other hand, the high frequency power supply unit 5 and the DC pulse generation unit 3 are simultaneously turned on, for example, and a negative DC pulse voltage of 1 MHz, for example, is applied to the lower electrode 21, and a high frequency voltage for plasma generation of 100 MHz, for example, is applied to the high frequency power supply unit 5. Apply. In this way, power is supplied to the processing gas, the processing gas is turned into plasma, and a silicon film is formed (plasma processing) (step S12).

  On the other hand, in parallel with the film forming process, an ion energy distribution pattern is acquired by the ion energy measuring means (step S13). Acquisition of this ion energy distribution pattern is the same as in the first step. Next, it is evaluated whether the acquired ion energy distribution pattern matches the ideal pattern of ion energy distribution (step S14). Whether or not this pattern is matched is determined by, for example, whether or not the overlapping regions of the ion energy are matched. This includes cases where it occurs somewhat.

  If the pattern is correct, the application pattern of the DC pulse voltage set by the DC pulse generator 3 is acquired as a determined value (step S15). On the other hand, if the pattern does not match, the process goes to step S11. Returning, the waveform pattern of the DC pulse voltage is finely adjusted, and the subsequent steps are repeated.

  According to such a plasma processing bias voltage determination method, in the experimental apparatus, the DC pulse generator 3 is directly connected to the wafer W, and a matching box or impedance element is connected between the DC pulse generator 3 and the wafer W. Therefore, a rectangular wave can be directly applied to the wafer W. Therefore, an ion energy distribution corresponding to the applied DC pulse voltage can be obtained, and the adjustment of the DC pulse voltage when securing an ideal pattern of the ion energy distribution is facilitated.

  On the other hand, in the actual plasma processing apparatus, although not shown in the figure, since a matching box and an impedance element exist between the DC pulse generator 3 and the wafer W as described above, in the waveform pattern of the DC pulse voltage. A rectangular wave is not always obtained. However, the ideal pattern of the DC pulse voltage application pattern for obtaining the ideal pattern of the ion energy distribution is generally within a reasonable range and does not deviate greatly from this ideal pattern. The bias voltage can be easily determined. Moreover, it is only necessary to adjust the application pattern of the DC pulse voltage to match the ideal pattern of the ion energy distribution, and if the plasma processing apparatus is configured as described above, the ion energy distribution can be acquired simultaneously with the adjustment of the DC pulse voltage. The application pattern of the DC pulse voltage can be easily determined as compared with the case where the crystallinity and etching shape are inspected with another apparatus.

  In the plasma processing apparatus of the present invention, the high-frequency power supply unit that supplies high-frequency power for converting the processing gas into plasma is an ordinary parallel plate type plasma processing apparatus having an upper electrode and a lower electrode. It may be one that supplies high-frequency power for turning the processing gas into plasma, one that emits a high-frequency power source from a microwave antenna, or one that generates plasma by induction heating. In the parallel plate type plasma processing apparatus, a high frequency power for converting the processing gas into plasma and a bias voltage that is a DC pulse voltage may be applied to a mounting table that also serves as a lower electrode.

W Semiconductor wafer 11 Vacuum chamber 2 Mounting table 3 DC pulse generator C Delivery means 4 Gas shower head 5 High frequency power supply

Claims (9)

A vacuum chamber in which a placement unit on which a substrate is placed is disposed;
A gas supply unit for supplying a processing gas for plasma processing into the vacuum chamber;
A plasma generation unit that supplies power to the processing gas to convert the processing gas into plasma;
A bias power supply unit that applies a bias voltage that is a DC pulse voltage to the mounting unit;
The bias power supply unit
In the ion energy distribution diagram in which the ion energy value is taken on the horizontal axis and the ion frequency is taken on the vertical axis, the amplitude values are expressed by utilizing the fact that a peak appears corresponding to the amplitude value of the DC pulse voltage. Different types of DC pulse voltages are generated, so that the ion energy distribution pattern in which the adjacent peaks overlap in the distribution diagram to form an overlapping region is adjusted to be a pattern suitable for plasma processing. A plasma processing apparatus.   The plasma processing apparatus according to claim 1, wherein the DC pulse voltage is a rectangular wave. The DC pulse voltage is generated such that the amplitude value of one DC pulse voltage changes stepwise,
The bias power supply unit includes a plurality of DC pulses having different amplitude values in order to make the ion energy distribution pattern suitable for plasma processing by overlapping adjacent peaks in the ion energy distribution diagram. 2. The plasma processing apparatus according to claim 1, wherein instead of generating a voltage, an amplitude value which changes stepwise in one DC pulse voltage is adjusted. The plasma generation unit includes a high frequency power supply unit that supplies high frequency power for converting the processing gas into plasma between the electrodes,
In the ion energy distribution diagram, a peak corresponding to the high-frequency power of the high-frequency power supply unit overlaps with the overlapping region formed based on the bias voltage to form a further overlapping region, and ion energy distribution suitable for plasma processing The plasma processing apparatus according to any one of claims 1 to 3, wherein the plasma processing apparatus is a pattern. Placing the substrate on the placement portion in the vacuum chamber;
Supplying a processing gas for plasma processing into the vacuum chamber;
Supplying electric power to the processing gas to turn the processing gas into plasma;
Applying a bias voltage, which is a DC pulse voltage, to the mounting portion,
The step of applying the bias voltage is as follows:
In the ion energy distribution diagram in which the ion energy value is taken on the horizontal axis and the ion frequency is taken on the vertical axis, the amplitude values are expressed by utilizing the fact that a peak appears corresponding to the amplitude value of the DC pulse voltage. The bias voltage is generated in such a manner that a plurality of different DC pulse voltages are generated so that an ion energy distribution pattern in which the adjacent peaks in the distribution diagram overlap to form an overlap region becomes a pattern suitable for plasma processing. A plasma processing method, which is a step of applying a voltage.   The plasma processing method according to claim 5, wherein the DC pulse voltage is a rectangular wave. The DC pulse voltage is generated such that the amplitude value of one DC pulse voltage changes stepwise,
In the step of applying the bias voltage, in order to make the ion energy distribution pattern suitable for plasma processing by overlapping adjacent peaks in the ion energy distribution diagram, a plurality of the amplitude values are different from each other. 6. The plasma processing method according to claim 5, wherein instead of applying the DC pulse voltage, a DC pulse voltage whose amplitude value changes stepwise in one DC pulse voltage is applied. The step of turning the processing gas into plasma is performed by supplying high-frequency power from a high-frequency power supply unit to turn the processing gas into plasma,
In the ion energy distribution diagram, a peak corresponding to the high-frequency power of the high-frequency power supply unit overlaps with the overlapping region formed based on the bias voltage to form a further overlapping region, and ion energy distribution suitable for plasma processing The plasma processing method according to claim 5, wherein the high-frequency power is applied so as to form a pattern. In a state where the substrate is mounted on the mounting portion in the vacuum chamber, power is supplied to the processing gas supplied into the vacuum chamber to turn the processing gas into plasma to generate plasma. Plasma treatment is performed on the substrate while applying a bias voltage, which is a DC pulse voltage, by the bias power supply unit,
The bias power supply unit
In the ion energy distribution diagram in which the ion energy value is taken on the horizontal axis and the ion frequency is taken on the vertical axis, the amplitude values are expressed by utilizing the fact that a peak appears corresponding to the amplitude value of the DC pulse voltage. To generate a plurality of different types of DC pulse voltages, thereby adjusting an ion energy distribution pattern in which peaks adjacent to each other in the distribution map overlap to form an overlapping region,
Various application patterns of the bias voltage are set, the plasma treatment is performed for each setting, and the bias voltage is applied so that a good plasma treatment can be obtained based on the plasma treatment result of the substrate after each plasma treatment. A method for determining a bias voltage for plasma processing, wherein a pattern is obtained.

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