JP2021144892A - Plasma processing apparatus - Google Patents

Abstract

To provide a plasma processing apparatus capable of suppressing deviation of the center of a generated plasma from the center of a processing surface of a processing target object even when the center of an antenna is away from a central axis of a chamber in plan view.SOLUTION: A plasma processing apparatus includes: a chamber having a substantially cylindrical shape; a gas supply unit which can supply gas to the inside of the chamber; a mounting portion which is provided inside the chamber and on which the processing target object can be mounted; a depressurization portion which can depressurize the inside of the chamber; a window which is provided at a position of the chamber opposing to the mounting portion, and contains a dielectric material; a circular antenna which is provided outside the chamber through the window and has at least one conductor; and a power source which applies power to the antenna. The center of the antenna is provided at a position away from a central axis of the chamber. By a ratio of an outer diameter of the antenna to an inner diameter of the chamber, the distribution of a high-frequency induction current in a plasma on a side near to an inner wall of the chamber is offset by a high-frequency induction current flowing through the inner wall of the chamber.SELECTED DRAWING: Figure 1

Description

An embodiment of the present invention relates to a plasma processing apparatus.

Inductively coupled plasma (ICP) is one of the plasmas generated by applying high frequency power. Inductively coupled plasma is widely used for various types of plasma processing because it can generate high-density plasma in a wide area.

Plasma processing equipment capable of generating inductively coupled plasma includes a chamber, a mounting portion provided inside the chamber on which the processed material is placed, and a position outside the chamber facing the processing surface of the processed material. An antenna for plasma excitation provided is provided.
Further, the plasma processing apparatus is provided with a detection unit for detecting the processing state of the processed object and the plasma state. For example, the processed object is irradiated with light, and the end point (end point) of the processing is detected based on the change in the interference light between the reflected light from the processed object and the irradiated light.

Here, in consideration of reducing the in-plane distribution of the processing rate (for example, the etching rate), it is preferable that the center of the generated plasma does not deviate from the center of the processing surface of the processed object in a plan view. .. In general, plasma is generated directly under the antenna, so that the center of the antenna overlaps the central axis of the chamber (the center of the mounting portion) in a plan view.

Further, it is preferable that the detection unit is provided at a position outside the chamber facing the processing surface of the processed object. However, an antenna is provided outside the chamber at a position facing the processing surface of the processed object.

In this case, if the detection unit is provided while avoiding the antenna, detection at a desired position on the processing surface may not be possible. It is conceivable to detect the state of the processed object from the side opposite to the processed surface, but it is difficult to detect the processed object in the case of a processed object that does not transmit light.
On the other hand, as described above, in general, plasma is generated directly under the antenna, so if the antenna is provided while avoiding the detection unit, the center of the generated plasma shifts the antenna from the center of the processing surface. It will shift. Therefore, the uniformity of the in-plane distribution of the processing rate may deteriorate.

Therefore, in a plan view, even if the center of the antenna is separated from the central axis of the chamber (the center of the mounting portion), it is possible to prevent the center of the generated plasma from shifting from the center of the processing surface of the processed object. The development of a plasma processing device has been desired.

JP-A-2017-152445

The problem to be solved by the present invention is to prevent the center of the generated plasma from deviating from the center of the processing surface of the processed object even if the center of the antenna is separated from the central axis of the chamber in a plan view. It is to provide a plasma processing apparatus capable of this.

The plasma processing apparatus according to the embodiment includes a chamber having a substantially cylindrical shape, a gas supply unit capable of supplying gas to the inside of the chamber, and a mounting unit provided inside the chamber on which a processed material can be placed. A decompression unit capable of depressurizing the inside of the chamber, a window provided at a position facing the previously described mounting portion of the chamber, and a window containing a dielectric material, and an outside of the chamber via the window. A circular antenna having at least one conductor and a power source for applying power to the antenna. The center of the antenna is provided at a position separated from the central axis of the chamber, and the side of the distribution of the high-frequency induced current in the plasma near the inner wall of the chamber is determined by the ratio of the outer diameter of the antenna to the inner diameter of the chamber. , It is offset by the high frequency induced current flowing through the inner wall of the chamber.

According to the embodiment of the present invention, even if the center of the antenna is separated from the central axis of the chamber in a plan view, the center of the generated plasma can be suppressed from being deviated from the center of the processing surface of the processed object. A plasma processing apparatus is provided.

It is a schematic cross-sectional view for exemplifying the plasma processing apparatus which concerns on this embodiment. (A) is a schematic diagram for exemplifying an antenna. (B) is a schematic diagram for exemplifying an antenna according to another embodiment. It is a schematic diagram for exemplifying the case where the center of a circular antenna having a plurality of conductors is deviated from the central axis of the chamber. It is a graph for exemplifying the relationship between the deviation amount of the center (center of the circumference) of an antenna, and the movement amount (displacement amount) of plasma. It is a graph for exemplifying the relationship between the outer diameter of the antenna and the movement amount (shift amount) of plasma when the center of an antenna is deviated by 60 mm from the central axis of a chamber.

Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, similar components are designated by the same reference numerals and detailed description thereof will be omitted as appropriate.
FIG. 1 is a schematic cross-sectional view for exemplifying the plasma processing apparatus 1 according to the present embodiment. As shown in FIG. 1, the plasma processing device 1 includes a chamber 2, a window 3, a mounting unit 4, a power supply 5, a power supply 6, a gate valve 7, a gas supply unit 8, a pressure reducing unit 9, a detection unit 10, and an antenna 11. , Faraday shield 12, cover 13, and controller 14 can be provided.

The chamber 2 has a substantially cylindrical shape with both ends closed. The chamber 2 has an airtight structure capable of maintaining an atmosphere depressurized from atmospheric pressure. The chamber 2 can be formed from a metal such as, for example, an aluminum alloy. Also, the chamber 2 can be grounded. A region 2a in which plasma P is generated is provided inside the chamber 2.

The chamber 2 can have a side surface, a top plate 2c, and a bottom surface 2e. On the side surface of the chamber 2, a carry-in / carry-out outlet 2b for carrying in / out the processed material 100 can be provided. The carry-in / carry-out outlet 2b can be airtightly closed by the gate valve 7.

The top plate 2c of the chamber 2 may be provided with a hole 2c1 penetrating in the thickness direction. The center of the hole 2c1 can be provided on the central axis 2d of the chamber 2. The hole 2c1 can transmit an electromagnetic field.

The window 3 has a plate shape and can be provided on the top plate 2c of the chamber 2. The window 3 can be provided so as to close the hole 2c1. The window 3 is provided at a position of the chamber 2 facing the mounting portion 4. That is, the window 3 faces the mounting surface of the mounting portion 4. The window 3 is preferably formed of, for example, a material that can transmit light and an electromagnetic field and is difficult to be etched when the etching process is performed. The window 3 can be formed from a dielectric material such as quartz.

The mounting portion 4 can be provided inside the chamber 2 and below the region 2a where the plasma P is generated (for example, the bottom surface 2e of the chamber 2). The mounting portion 4 may have, for example, an electrode 4a, an insulating portion 4b, and a pedestal 4c.
The electrode 4a can be formed from a conductive material such as metal. The electrode 4a can be attached to the pedestal 4c, for example. The upper surface of the electrode 4a can be a mounting surface on which the processed object 100 is mounted. The position of the center of the processed object 100 mounted on the mounting portion 4 is set to be on the central axis 2d of the chamber 2.

The processed object 100 can be, for example, a photomask, a mask blank, a wafer, a glass substrate, or the like. However, the processed product 100 is not limited to the illustrated product.

The insulating portion 4b is provided between the electrode 4a and the pedestal 4c. The insulating portion 4b insulates between the electrode 4a and the pedestal 4c. The insulating portion 4b can be formed from a dielectric material (for example, quartz or the like) or the like.

The pedestal 4c can be attached to, for example, the bottom surface 2e of the chamber 2. The pedestal 4c can be formed from a metal such as an aluminum alloy, for example.
Further, the mounting unit 4 may be provided with a pickup pin, a temperature control unit, or the like.

The power supply 5 can be electrically connected to the antenna 11 via the matching unit 5a. The power source 5 can be a high frequency power source for generating the plasma P. The power supply 5 generates high-frequency discharge in the region 2a where the plasma P is generated inside the chamber 2 to generate the plasma P. The power supply 5 can apply high-frequency power having a frequency of, for example, about 100 KHz to 100 MHz to the antenna 11. In this case, the power supply 5 can apply high frequency power having a relatively high frequency (for example, 13.56 MHz) suitable for generating the plasma P to the antenna 11.

The matching device 5a is provided to match the impedance on the power supply 5 side with the impedance on the plasma P side. The matching device 5a may have a matching circuit or the like for matching impedance.

The power supply 6 can be electrically connected to the electrode 4a of the mounting portion 4 via the matching device 6a. The power supply 6 can be a so-called high-frequency power supply for bias control. The power supply 6 can be provided to control the energy of the ions drawn into the processed object 100 mounted on the mounting unit 4. The power supply 6 can apply high frequency power having a relatively low frequency (for example, 13.56 MHz or less) suitable for attracting ions to the electrode 4a.

The matching device 6a is provided to match the impedance on the power supply 6 side and the impedance on the plasma P side. The matching device 6a may have a matching circuit or the like for matching impedance.

The gate valve 7 can have a door with a sealing member such as an O-ring. The door can be opened and closed by an opening / closing mechanism. When the door is closed, the seal member is pressed around the carry-in / carry-out outlet 2b, and the carry-in / carry-out outlet 2b is airtightly closed.

The gas supply unit 8 can supply the gas G to the region 2a in which the plasma P is generated inside the chamber 2. The gas supply unit 8 may include a gas storage unit 8a, a gas control unit 8b, and an on-off valve 8c. The gas storage unit 8a, the gas control unit 8b, and the on-off valve 8c can be provided outside the chamber 2.

The gas storage unit 8a stores the gas G and can supply the stored gas G to the inside of the chamber 2. The gas storage unit 8a can be, for example, a high-pressure cylinder that stores the gas G. The gas storage unit 8a and the gas control unit 8b can be connected via a pipe.

The gas control unit 8b can control the flow rate and pressure of the gas G supplied from the gas storage unit 8a to the inside of the chamber 2. The gas control unit 8b can be, for example, an MFC (Mass Flow Controller) or the like. The gas control unit 8b and the on-off valve 8c can be connected via a pipe.

The on-off valve 8c can be connected to the nozzle 2f provided in the chamber 2 via a pipe. A plurality of nozzles 2f may be provided, and the gas G may be evenly supplied to the region 2a where the plasma P is generated from a plurality of directions. The on-off valve 8c can control the supply and stop of the gas G. The on-off valve 8c can be, for example, a 2-port solenoid valve or the like. The gas control unit 8b can also have the function of the on-off valve 8c.

Gus G can be assumed to generate desired radicals and ions when excited and activated by plasma P. For example, when the plasma treatment is an etching treatment, the gas G can generate radicals and ions capable of etching the treated surface 100a of the processed product 100. In this case, the gas G can be, for example, a gas containing chlorine, a gas containing fluorine, or the like. The gas G can be, for example, a mixed gas of chlorine gas and oxygen gas, a mixed gas of CHF ₃ , _{a mixed gas of CHF 3} and CF _4, a mixed gas of SF ₆ and helium gas, and the like. The type of treatment and the components of gas G are not limited to those illustrated.

The decompression unit 9 decompresses the inside of the chamber 2 so that the pressure becomes a predetermined pressure. The decompression unit 9 may include a pump 9a and a pressure control unit 9b. The pump 9a and the pressure control unit 9b can be provided outside the chamber 2.
The pump 9a can exhaust the gas inside the chamber 2. The pump 9a can be, for example, a turbo molecular pump (TMP) or the like. As a back pump, a roots type dry pump can also be connected to a turbo molecular pump.

The pressure control unit 9b can be connected to the pump 9a via a pipe. The pressure control unit 9b can control the internal pressure of the chamber 2 to become a predetermined pressure based on the output of a vacuum gauge or the like that detects the internal pressure of the chamber 2. The vacuum gauge can be a diaphragm type capacitance manometer or the like. The pressure control unit 9b can be, for example, an APC (Auto Pressure Controller) or the like.

The detection unit 10 can detect the processing state of the processed object 100 and the plasma state based on the optical change that occurs during the plasma processing. For example, the detection unit 10 can detect the end point of the plasma processing.

The detection unit 10 can have a detection head 10a and a control unit 10b. The detection head 10a and the control unit 10b can be provided outside the chamber 2.
The detection head 10a can face the processing surface 100a (upper surface) of the processed object 100 mounted on the mounting portion 4 via the window 3. The detection head 10a can be provided on the outside of the window 3 side by side with the antenna 11.

The control unit 10b can be connected to the detection head 10a via, for example, an optical fiber. The control unit 10b can be, for example, a processing process monitor that analyzes optical changes. The processing process monitor can be, for example, a spectroscope for reflectance measurement. If a spectroscope is provided, light having a predetermined wavelength can be extracted, so that the detection accuracy can be improved. Further, the control unit 10b may be provided with a monitor or the like for displaying the processing status. The control unit 10b can transmit the analysis result to the controller 14.

When the detection unit 10 detects the processing state of the processing surface 100a based on the interference light, the detection head 10a irradiates the processing surface 100a with light as shown in FIG. The reflected light from the processing surface 100a is incident on the detection head 10a. If the detection head 10a faces the processing surface 100a, the light emitted from the detection head 10a is incident on the processing surface 100a from a direction perpendicular to the processing surface 100a. Further, the reflected light from the processing surface 100a is directly incident on the detection head 10a. Therefore, it becomes easy to detect the processing state of the processed object 100 (for example, the end point of the plasma processing).

Further, the detection unit 10 can also detect the processing state of the processed object 100 (for example, the end point of the plasma processing) based on the emission spectrum of the plasma P. For example, atoms and molecules emitted from the processing surface 100a by etching collide with electrons in plasma P and are excited. Light is emitted when the excited state returns to the ground state. The emitted light has an emission spectrum peculiar to each atom and each molecule. If attention is paid to a spectrum line related to a desired material from the emission spectrum, the processing state of the processed object 100 (for example, the end point of plasma processing) can be detected by the fluctuation of the spectrum line.

In such a case, it is necessary to make the light from the plasma P enter the detection head 10a. If the detection head 10a faces the processing surface 100a, the detection head 10a faces the plasma P, so that the light from the plasma P directly enters the detection head 10a. Therefore, it becomes easy to detect the processing state of the processed object 100 (for example, the end point of the plasma processing).

That is, the detection unit 10 may use the light reflected from the processing surface 100a or the light from the plasma P.
However, the gas excited in the plasma may make the emission spectrum broad and difficult to detect. Further, when most of the processed surface 100a is covered with a resist, the proportion of the processed surface 100a to be etched is small. Therefore, the influence of the material of the treated surface 100a on the emission spectrum is reduced, and the detection becomes more difficult.

Since the spectrum of reflected light differs greatly depending on the material with respect to the emission spectrum of plasma P, it is measured with a spectroscope for measuring reflectance (a spectroscope that emits light from an internal emission source and measures the returned light). Then, the end point of the plasma processing can be detected relatively easily. Further, even if most of the treated surface 100a is covered with a resist, if there is no resist in the region exposed to light, the resist does not hinder the detection of the end point of the plasma treatment. Therefore, it is more preferable that the detection unit 10 uses the reflected light from the processing surface 100a.

The antenna 11 can be provided outside the chamber 2. The antenna 11 can be provided on the outside of the window 3.
FIG. 2A is a schematic diagram for exemplifying the antenna 11.
FIG. 2B is a schematic diagram for exemplifying the antenna 110 according to another embodiment.
As shown in FIGS. 2A and 2B, a plurality of conductors 11a can be provided on the antennas 11 and 110. The inductances L of the plurality of conductors 11a can have the same value. The value of the inductance L may vary slightly. For example, the value of the inductance L may vary within the margin of error during manufacturing.

The plurality of conductors 11a can be arranged on the circumference. The plurality of conductors 11a can be arranged at equal intervals. The plurality of conductors 11a can be provided at positions that are rotationally symmetric with each other. The plurality of conductors 11a are connected in parallel to the power supply 5. That is, each of one end of the plurality of conductors 11a is electrically connected to the terminal 5b1 of the power supply 5. Each of the other ends of the plurality of conductors 11a can be grounded.

If the antennas 11 and 110 having such a configuration are provided, an electromagnetic field is introduced at a position that is rotationally symmetric with respect to the centers of the plurality of conductors 11a arranged on the circumference (centers of the antennas 11 and 110). can do. Further, the plurality of conductors 11a are connected in parallel, and the inductance L has the same value. Therefore, an electromagnetic field having the same strength can be introduced at a position inside the chamber 2 that is rotationally symmetric with each other. That is, an electromagnetic field having the same strength can be introduced at a position in the plasma P that is rotationally symmetric with each other.

As a result, it becomes easy to generate plasma P having a uniform density, and it becomes easy to maintain plasma P having a uniform density. In addition, the uniformity of the treatment in the plane of the processed product 100 (for example, the uniformity of the etching rate) can be improved.

As shown in FIGS. 2A and 2B, a current I flows through the plurality of conductors 11a. Since the plurality of conductors 11a are connected in parallel, the value of the current flowing through the power supply 5 may become too large. Therefore, the phase adjusting unit 5c that controls the phase can be connected in parallel to the power supply 5. The absolute value of the susceptance of the phase adjusting unit 5c can be made substantially the same as the absolute value of the susceptance of the conductor 11a.

The phase in the phase adjusting unit 5c can be opposite to the phase in the conductor 11a. In this way, a current of opposite phase can flow through the power source 5 with the same amplitude as the current I flowing through the conductor 11a. Therefore, the total susceptance is reduced, and the total current flowing through the power source 5 is suppressed. As a result, overheating of the power supply 5 can be suppressed.

Further, as shown in FIG. 2B, a capacitor 11b connected in series to each of the plurality of conductors 11a can be provided. The capacitor 11b can be connected to the grounded end of the conductor 11a. The capacitances C of the plurality of capacitors 11b can have the same value. The value of the capacity C may vary slightly. For example, the value of the capacitance C may vary within the margin of error during manufacturing.

By connecting the capacitor 11b to the ground-side end of the conductor 11a, the reactances of the plurality of conductors 11a and the reactances of the capacitors 11b can be partially or completely offset. Therefore, the impedance of the antenna 11 is lowered, and the maximum value of the antenna potential can be lowered. If the maximum value of the antenna potential can be lowered, it is possible to prevent the window 3 and the like from being damaged by the abnormal discharge.

As shown in FIG. 1, the center of the antenna 11 (center 11c of the circumference) is provided at a position separated from the central axis 2d of the chamber 2. Further, the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2g of the chamber 2 can be, for example, 0.62 or more and 0.68 or less. By setting the ratio value within this range, it is possible to prevent the center of the generated plasma P from deviating from the central axis 2d of the chamber 2.
The details of the reason why the movement (displacement) of the plasma P can be suppressed will be described later.

The Faraday shield 12 can be provided between the antenna 11 and the window 3. If the Faraday shield 12 is provided, it is possible to suppress the formation of a current path in the same direction as the direction of the high-frequency electric field by the antenna 11. Therefore, a high-frequency electric field can be generated inside the chamber 2, and capacitive coupling between the antenna 11 and the plasma P can be suppressed. As a result, the energy of the electromagnetic field introduced from the antenna 11 can be efficiently used to generate the plasma P.

Further, since the capacitive coupling between the antenna 11 and the plasma P can be suppressed, it is possible to suppress the negative bias applied to the window 3 and the like during the plasma processing. Therefore, it is possible to suppress the collision of the ions in the plasma P with the window 3, so that the damage to the window 3 can be suppressed.

The cover 13 has a box shape and covers the side of the chamber 2 where the window 3 is provided. Inside the cover 13, an antenna 11, a Faraday shield 12, a detection head 10a of the detection unit 10, and the like can be provided.

The controller 14 may include an arithmetic element such as a CPU (Central Processing Unit) and a storage element such as a semiconductor memory. The controller 14 can be, for example, a computer. The controller 14 can control the operation of each element provided in the plasma processing device 1 based on the control program stored in the storage element.

Here, as described above, the plurality of conductors 11a introduce an electromagnetic field into the chamber 2 through the window 3. Therefore, in general, a plurality of conductors 11a are arranged in a circle about the central axis 2d of the chamber 2 in order to generate plasma P having a uniform density inside the chamber 2.

FIG. 3 is a schematic view for exemplifying a case where the center 11c of the circular antenna 11 having the plurality of conductors 11a is deviated from the central axis 2d of the chamber 2.
As shown in FIG. 3, generally, when the center 11c of the circumference provided with the plurality of conductors 11a deviates from the central axis 2d of the chamber 2, the center of the generated plasma P is on the center 11c side of the antenna 11. It will shift to. If the center of the generated plasma P deviates from the central axis 2d of the chamber 2, the center of the generated plasma P deviates from the center of the processed object 100, so that the uniformity of the in-plane distribution of the processing rate may deteriorate. be.

Therefore, in general, it is necessary to strictly align the center 11c of the circumference provided with the plurality of conductors 11a with the central axis 2d of the chamber 2, which causes an increase in manufacturing cost and a decrease in productivity. ..

Furthermore, in recent years, the processing pattern has become finer, and for example, the opening ratio of irregularities and holes formed has become extremely small. In such a case, the amount of the material to be processed is small, so that the amount of change in light is very small. Further, the above-mentioned processing pattern is generally formed in the central region of the processed product 100. Therefore, most of the central region is covered with resist. Therefore, in the central region, the amount of material exposed from the resist tends to decrease, and detection based on the amount of change in light becomes more difficult.

On the other hand, the peripheral region of the processed product 100 can be a region in which the above-mentioned processing pattern is not formed. Therefore, as shown in FIG. 1, a relatively wide detection region 100b that is not covered with a resist can be provided in the peripheral region of the processed product 100. That is, although the resist is provided on the treated surface 100a, the detection region 100b is exposed from the resist. Since the processing surface 100a of the processed object 100 can be exposed in the detection region 100b, the amount of the material to be processed can be increased. As the amount of the material to be processed increases, the amount of change in light increases, so that it becomes easy to detect the state of plasma and the state of the processed object, and the detection accuracy can be improved.

However, as described above, in general, a plurality of conductors 11a are arranged on the circumference centered on the central axis 2d of the chamber 2. Further, the antenna 11 may be provided with a plurality of capacitors 11b, or a Faraday shield 12 may be provided between the antenna 11 and the window 3.

That is, when the antenna is arranged as in the conventional case, the peripheral region of the processed object 100 provided with the detection region 100b may overlap with the conductor 11a, the capacitor 11b, the Faraday shield 12, and the like in a plan view. If the conductor 11a, the capacitor 11b, the Faraday shield 12, and the like are provided above the peripheral region of the processed object 100, it becomes difficult to provide the detection head 10a above the detection region 100b.

In this case, a method of providing the detection head 10a in a direction inclined with respect to the detection region 100b can be considered. However, in this method, it becomes difficult for the reflected light to enter the detection head 10a. Therefore, the accuracy of detection using reflected light (detection based on a change in interference light) may decrease.

Therefore, the present inventor has conducted an earnest investigation into how the center of the plasma P moves by shifting the center 11c of the antenna 11 from the central axis 2d of the chamber 2.

First, the present inventor conducted an investigation using an antenna 11 having an outer diameter of 11d of 240 mm. Then, it was found that when the antenna 11 is moved from the central axis 2c of the chamber 2 (for example, the left side), the center of the plasma P shifts in the same direction as the moving direction of the antenna 11 (left side). This result had the same tendency as the result shown in FIG.
The outer diameter 11d of the antenna 11 is the length of a line segment connecting the outer ends of the conductors 11a located at positions facing each other through the center 11c of the antenna 11 in a plan view (see FIG. 1).

Next, the present inventor conducted an investigation using an antenna 11 having an outer diameter of 11d of 270 mm. Then, it was found that when the antenna 11 is moved from the central axis 2c of the chamber 2 (for example, the left side), the center of the plasma P shifts in the direction opposite to that of the antenna 11 (right side). This result tended to be different from the result shown in FIG.

From the above two findings, the present inventor considers that there is a range of the outer diameter 11d of the antenna in which the center of the plasma P does not shift even if the antenna 11 is moved from the central axis 2c of the chamber 2. And further investigation was conducted.

FIG. 4 is a graph for exemplifying the relationship between the deviation amount of the center of the antenna 11 (center 11c of the circumference) and the movement amount (displacement amount) of the plasma P.
A negative value of "movement amount of plasma P", which is the vertical axis in FIG. 4 and FIG. 5 described later, means that the plasma moves in the direction opposite to the direction in which the center 11c of the antenna deviates. Further, 240 mm to 270 mm in FIG. 4 is the outer diameter 11d of the antenna 11. Further, FIG. 4 and FIG. 5 described later show a case where the inner diameter 2 g of the chamber 2 is 400 mm.

As can be seen from FIG. 4, the present inventor sets the outer diameter 11d of the antenna 11 to 260 mm, and even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm, the amount of movement of the plasma P (deviation). It was found that the quantity) can be made almost 0 (zero).

The reason why the amount of movement (displacement) of plasma P can be suppressed is not always clear, but it can be considered as follows.
When a high-frequency current is passed through the antenna 11, a vortex-shaped high-frequency electric field is induced in the plasma-generated gas inside the chamber 2. The vortex-shaped induced electric field causes a vortex-shaped high-frequency current to flow inside the plasma P. A plurality of conductors 11a arranged on the outside of the chamber 2 via the window 3 so as to be circular, and a spiral high-frequency current play the roles of the primary coil and the secondary coil of the high-frequency inducer.

Here, for example, when the antenna 11 is moved to the left side, the following two things are considered to occur.
(1) First, the high-frequency induced current in the plasma P increases on the left side approaching the inner wall of the chamber 2 and decreases on the right side away from the inner wall of the chamber 2.
(2) On the other hand, when the antenna 11 approaches the inner wall on the left side of the chamber 2, the induced current flowing on the inner wall on the left side increases, and the induced current flowing on the inner wall on the right side decreases. In this case, on the inner wall on the left side, the induced current flowing in the plasma P on the same side decreases as the induced current flowing through the inner wall increases. On the contrary, on the inner wall on the right side, the induced current flowing in the plasma P increases as the induced current flowing through the inner wall decreases. Therefore, as a result, the induced current in the plasma P on the left side decreases, and the induced current in the plasma P on the right side increases.

Then, it is considered that the induced current distribution in the plasma P when the antenna 11 is shifted is determined by the superposition of (1) and (2). The induced current distribution has a great influence on the plasma density distribution. Therefore, it is considered that the distribution of plasma P is also determined by the superposition of (1) and (2).
Furthermore, since (1) and (2) have opposite effects, the effect of superposition is determined by their quantitative relationship.

Here, regarding the amount of movement (displacement) of the plasma P when the above-mentioned antenna 11 having an outer diameter 11d of 240 mm and the antenna 11 having an outer diameter 11d of 270 mm are moved from the central axis 2c of the chamber 2, (1). ) And (2) will be described.

First, when the antenna 11 having an outer diameter 11d of 240 mm is shifted to the left from the central axis 2c of the chamber 2, the amount of increase in the high-frequency induced current in the plasma P around the inner wall on the left side of the chamber 2 due to the movement of the antenna 11 is increased. It becomes larger than the decrease amount of the high frequency induced current due to the increase of the high frequency induced current flowing through the inner wall. Then, the amount of decrease in the high-frequency induced current in the plasma P around the inner wall on the right side of the chamber 2 due to the movement of the antenna 11 becomes larger than the amount of increase in the high-frequency induced current due to the decrease in the high-frequency induced current flowing through the inner wall. That is, it is considered that the influence of (1) is larger than the influence of (2). Therefore, when the antenna 11 is moved to the left side, it is considered that the plasma density on the left side increases and the plasma density on the right side decreases. Then, as a result of this phenomenon, it is considered that the plasma distribution shifts in the same direction (left side) as the antenna 11.

On the other hand, when the antenna 11 having an outer diameter 11d of 270 mm is shifted to the left from the central axis 2c of the chamber 2, the amount of increase in the high-frequency induced current in the plasma P around the inner wall on the left side of the chamber 2 due to the movement of the antenna 11 is increased. It is smaller than the decrease in the high-frequency induced current due to the increase in the high-frequency induced current flowing through the inner wall. Then, the amount of decrease in the high-frequency induced current in the plasma P around the inner wall on the right side of the chamber 2 due to the movement of the antenna 11 is smaller than the amount of increase in the high-frequency induced current due to the decrease in the high-frequency induced current flowing through the inner wall. That is, it is considered that the influence of (2) is larger than the influence of (1). Therefore, when the antenna 11 is moved to the left side, it is considered that the plasma density on the left side decreases and the plasma density on the right side increases. Then, as a result of this phenomenon, it is considered that the plasma distribution shifts in the direction opposite to that of the antenna 11 (right side).

In this way, (1) and (2) have opposite effects, so the effect of superposition is determined by their quantitative relationship. Further, the effect of superposition is not determined only by the amount of deviation between the center 11c of the antenna 11 and the central axis 2d of the chamber 2 and the outer diameter 11d of the antenna 11, but also the inner diameter 2g of the chamber 2 and the outer diameter 11d of the antenna 11. It is thought that it will change depending on the relationship with.

Based on the above findings, the present inventor considers that if the relationship between the inner diameter 2 g of the chamber 2 and the outer diameter 11d of the antenna 11 is within a predetermined range, the center 11c of the circumference provided with the plurality of conductors 11a is located. It has been found that even if the center of the generated plasma P deviates from the central axis 2d of the chamber 2, the center of the generated plasma P can be suppressed from deviating from the central axis 2d of the chamber 2.

By the way, depending on the purpose and specifications of the treatment, if the movement amount (deviation amount) of the plasma P is within ± 10 mm, the in-plane distribution of the treatment rate (for example, the etching rate) can be allowed. As can be seen from FIG. 4, unless the outer diameter 11d of the antenna 11 is 260 mm, the farther the center 11c of the antenna 11 is from the central axis 2d of the chamber 2, the larger the amount of movement (displacement) of the plasma P. Become.
Therefore, when the center 11c of the antenna 11 is deviated from the central axis 2d of the chamber 2 by 60 mm, the relationship between the outer diameter 11d of the antenna 11 and the movement amount (displacement amount) of the plasma P is investigated.

FIG. 5 is a graph for exemplifying the relationship between the outer diameter 11d of the antenna 11 and the movement amount (shift amount) of the plasma P when the center 11c of the antenna 11 is deviated from the central axis 2d of the chamber 2 by 60 mm. be.
Note that FIG. 5 shows a case where the inner diameter 2 g of the chamber 2 is 400 mm. The lower horizontal axis represents the value of the outer diameter 11d of the antenna 11, and the upper horizontal axis is the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2g of the chamber 2 (outer diameter 11d of the antenna 11 / chamber 2). The value of inner diameter 2g) is shown.

As can be seen from FIG. 5, if the outer diameter 11d of the antenna 11 is 248 mm or more and 270 mm or less, even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm, the amount of movement of the plasma P (displacement amount). ) Is within ± 10 mm, which is preferable.

Further, as can be seen from FIG. 5, if the outer diameter 11d of the antenna 11 is 254 mm or more and 266 mm or less, even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm, the amount of movement of the plasma P ( The amount of deviation) is within ± 5 mm, which is more preferable.

Further, as can be seen from FIG. 5, if the outer diameter 11d of the antenna 11 is 260 mm, even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm, the movement amount (displacement amount) of the plasma P can be obtained. It can be made almost 0 (zero), which is more preferable.

Here, as described above, the amount of movement (displacement) of the plasma P is not determined only by the outer diameter 11d of the antenna 11, but is determined by the relationship between the inner diameter 2g of the chamber 2 and the outer diameter 11d of the antenna 11. Therefore, when the movement amount (displacement amount) of the plasma P is set to an arbitrary value or less, the relationship between the inner diameter 2 g of the chamber 2 and the outer diameter 11d of the antenna 11 needs to be within a predetermined range.

That is, as shown in FIG. 5, if the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2g of the chamber 2 (outer diameter 11d of the antenna 11 / inner diameter 2g of the chamber 2) is 0.62 or more and 0.68 or less. Even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm, the amount of movement (displacement) of the plasma P can be set to be within ± 10 mm.

More preferably, the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2 g of the chamber 2 is 0.63 or more and 0.66 mm or less. If the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2g of the chamber 2 is within the above range, the movement amount (shift amount) of the plasma P even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm. However, it is within ± 5 mm.

More preferably, the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2g of the chamber 2 is 0.65. Assuming that the ratio of the outer diameter 11d of the antenna 11 to the inner diameter 2g of the chamber 2 is 0.65, the movement amount (shift amount) of the plasma P even if the center 11c of the antenna 11 deviates from the central axis 2d of the chamber 2 by 60 mm. However, it can be set to almost 0 (zero).

In the plasma processing apparatus 1 according to the present embodiment, even if the center of the antenna 11 (center of the circumference 11c) is separated from the central axis 2d of the chamber 2 (center of the mounting portion 4) in a plan view. It is possible to prevent the center of the generated plasma P from deviating from the center of the processing surface 100a of the processed object 100. Therefore, the in-plane distribution of the processing rate can be reduced.

Further, since it is not necessary to strictly align the center 11c of the circumference provided with the plurality of conductors 11a with the central axis 2d of the chamber 2, it is possible to reduce the manufacturing cost and improve the productivity.

Further, if the center of the antenna 11 (center 11c of the circumference) can be shifted from the central axis 2d of the chamber 2, the conductor 11a, the capacitor 11b, the Faraday shield 12, and the like are not provided above the detection region 100b. Can be. Therefore, since the detection head 10a can be located in a direction substantially perpendicular to the detection region 100b, it becomes easy to detect the processing state (for example, the end point of plasma processing) of the processed object 100. In addition, the detection accuracy can be improved.

The embodiment has been illustrated above. However, the present invention is not limited to these descriptions.
With respect to the above-described embodiments, those skilled in the art with appropriate design changes are also included in the scope of the present invention as long as they have the features of the present invention.
For example, the shape, material, arrangement, and the like of the components included in the plasma processing apparatus 1 are not limited to those illustrated, and can be appropriately changed.
For example, in the above-described embodiment, the antenna 11 is formed of a plurality of conductors 11a, but may be an antenna formed of at least one conductor 11a.
Further, in the above-described embodiment, the detection region 100b is a portion exposed from the resist, but the present invention is not limited to this. For example, when a metal film used for a processing pattern such as chromium is used as a mask instead of the resist, the portion exposed from the mask may be used as the detection region 100b. In the above case, the detection region 100b may be a portion where processing can be easily observed, such as a pattern region relatively larger than other processing patterns, a pattern in which interference of incident / reflected light can be easily calculated and cannot be used as a device.
In addition, the elements included in each of the above-described embodiments can be combined as much as possible, and the combination thereof is also included in the scope of the present invention as long as the features of the present invention are included.

1 Plasma processing device, 2 chamber, 2d center axis, 2g inner diameter, 3 windows, 4 mounting part, 5 power supply, 6 power supply, 10 detection part, 10a detection head, 11 antenna, 11a conductor, 11c center, 11d outer diameter, 100 processed object, 100a processed surface, 100b detection area, 110 antenna, P plasma

Claims (8)

A chamber that is almost cylindrical and
A gas supply unit capable of supplying gas to the inside of the chamber,
A mounting portion provided inside the chamber on which the processed material can be mounted, and a mounting portion.
A decompression unit that can decompress the inside of the chamber,
A window of the chamber that is provided at a position facing the previously described placement and that contains a dielectric material.
A circular antenna provided outside the chamber through the window and having at least one conductor.
A power supply that applies power to the antenna and
With
The center of the antenna is provided at a position separated from the central axis of the chamber.
Plasma processing in which the side of the distribution of the high-frequency induced current in the plasma near the inner wall of the chamber is canceled by the high-frequency induced current flowing through the inner wall of the chamber by the ratio of the outer diameter of the antenna to the inner diameter of the chamber. Device. The plasma processing apparatus according to claim 1, wherein the ratio of the outer diameter of the antenna to the inner diameter of the chamber is 0.62 or more and 0.68 or less. The plasma processing apparatus according to claim 1 or 2, further comprising a detection head provided side by side with the antenna on the outside of the window. The plasma processing apparatus according to claim 3, further comprising a processing process monitor connected to the detection head. The plasma processing apparatus according to claim 4, wherein the processing process monitor is a spectroscope for measuring reflectance. A detection region for easy observation of the treatment is provided on the treatment surface of the processed product, and the detection head is located in any one of claims 3 to 5 in a direction substantially perpendicular to the detection region. The plasma processing apparatus described. The plasma processing apparatus according to claim 6, wherein a resist is provided on the processing surface, and the detection region is exposed from the resist. The plasma processing apparatus according to claim 6 or 7, wherein the detection region is provided in a peripheral region of the processed object.

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