JP7095029B2 - Plasma processing equipment - Google Patents

Description

Embodiments of the present invention relate to a plasma processing apparatus.

The plasma processing apparatus used for dry etching or the like is provided with a detection unit for detecting the state of the processed object. For example, in the detection of the end point of plasma processing, the end point of processing is detected based on the change in the scattering intensity of the light applied to the surface of the processed object. Further, in the detection of the end point of plasma processing, the end point of processing may be detected based on the change in the emission spectrum of plasma. Further, in the detection of the end point of the plasma treatment, the end point of the treatment may be detected based on the reflected light or the transmitted light in the region where the treatment is performed. That is, in general, the end point of the plasma processing is detected based on the optical change that occurs during the plasma processing.

Here, a detection window (transmission window) provided on the side surface of the chamber, a detection unit provided outside the chamber to detect plasma emission through the detection window, and a plasma processing apparatus provided are proposed. There is. In addition, it is provided with a plate-shaped window provided on the ceiling of the chamber, and a detection unit that enters the window from the inside of the chamber, propagates inside the window, and detects the light radiated from the side surface of the window. A plasma processing device has been proposed. These detection units detect light emission in a wide range, for example, the entire region where plasma is generated. In this case, the intensity of the light incident on the detection unit is the average value of the intensity of the light in a wide range, so that it is difficult to detect a slight change in the surface of the processed object.

In recent years, the processed portion has become finer, and for example, the aperture ratio of formed irregularities and holes may be 1% or less. In such a case, the amount of the substance to be removed is small, so that the amount of change in light is small. Therefore, when light emission in a wide range is detected, it becomes more difficult to detect a slight change in the surface of the processed material.

In this case, if the change in light in a narrow region can be detected, the end point of the processing can be detected with high accuracy even in the fine processing, and by extension, the fine processing can be performed with high accuracy.
Therefore, it has been desired to develop a plasma processing apparatus capable of detecting a change in light in a narrow region.

Japanese Unexamined Patent Publication No. 2007-66935

An object to be solved by the present invention is to provide a plasma processing apparatus capable of detecting a change in light in a narrow region.

The plasma processing apparatus according to the embodiment is provided with a chamber capable of maintaining an atmosphere depressurized from atmospheric pressure, a gas supply unit capable of supplying gas to the inside of the chamber, and a processed object inside the chamber. A mounting portion that can be mounted, a decompression portion that can depressurize the inside of the chamber, a window provided in the chamber facing the previously described mounting portion, and a window outside the chamber and in front of the window. A plasma generating portion provided on the surface opposite to the description portion side and capable of generating plasma inside the chamber, and a plasma generating portion locally provided inside the window and tilted with respect to the central axis of the chamber. It includes an optical path changing portion having a surface and a detection unit provided on the side surface side of the window and facing the surface of the optical path changing portion. The detection unit irradiates the surface of the processed object with light through the surface of the optical path changing portion, is reflected by the surface of the processed object, and light further reflected by the surface of the optical path changing portion can be incident. Is. The detection unit detects the end point of the plasma processing from the interference light.

According to an embodiment of the present invention, there is provided a plasma processing apparatus capable of detecting a change in light in a narrow region.

It is a schematic sectional drawing for exemplifying the plasma processing apparatus which concerns on this embodiment. It is a schematic perspective view for exemplifying a mounting module. It is a schematic cross-sectional view for exemplifying an optical path change part. (A) and (b) are schematic cross-sectional views for exemplifying the modification of the optical path change part. It is a schematic cross-sectional view for exemplifying another modification of the optical path change part. It is a schematic plan view for exemplifying the flat surface provided on the side surface of a window. (A) and (b) are schematic cross-sectional views for exemplifying an optical path changing part which concerns on other embodiments. It is a schematic sectional drawing for exemplifying the plasma processing apparatus which concerns on other embodiment.

Hereinafter, embodiments will be illustrated with reference to the drawings. In each drawing, the same 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 illustrating the plasma processing apparatus 1 according to the present embodiment. FIG. 2 is a schematic perspective view for exemplifying the mounting module 3.
As shown in FIG. 1, the plasma processing apparatus 1 includes a chamber 2, a mounting module 3, a power supply unit 4, a power supply unit 5, a decompression unit 6, a gas supply unit 7, a processing state detection unit 8, and a control unit 9. Can be provided.

The chamber 2 can have an airtight structure capable of maintaining an atmosphere depressurized from atmospheric pressure.
The chamber 2 can have a main body 21, a top plate 22, and a window 23.
The main body 21 has a substantially cylindrical shape, and a bottom plate 21a is integrally provided at one end thereof. The other end of the body 21 is open. The main body 21 can be formed of, for example, a metal such as an aluminum alloy. Further, the main body portion 21 can be grounded. Inside the main body 21, a region 21b where plasma P is generated is provided. The main body 21 may be provided with an carry-in / carry-out port 21c for carrying in / out the processed material 100. The carry-in / carry-out outlet 21c can be airtightly closed by the gate valve 21c1.

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 top plate 22 has a plate shape and can be provided so as to close the opening of the main body portion 21. The top plate 22 can be provided so as to face the bottom plate 21a. A hole 22a penetrating in the thickness direction can be provided in the central region of the top plate 22. The center of the hole 22a can be provided on the central axis 2a of the chamber 2 (main body 21). The hole 22a can be provided to transmit an electromagnetic wave radiated from the electrode 51 described later. The top plate 22 can be formed of, for example, a metal such as an aluminum alloy.

The window 23 has a plate shape and can be provided on the top plate 22. The window 23 can be provided so as to close the hole 22a. That is, the window 23 is provided in the chamber 2 and faces the mounting portion 31. The window 23 can be formed of a material that can transmit light and an electromagnetic field and is difficult to be etched when the etching process is performed. The window 23 can be formed from a dielectric material such as quartz.

As shown in FIGS. 1 and 2, the mounting module 3 can have a mounting portion 31, a support portion 32, and a cover 33. The mounting module 3 can have a cantilever structure in which the mounting module 3 projects from the side surface of the chamber 2 (main body 21) into the chamber 2 (main body 21) and the mounting portion 31 is provided on the distal end side. The processed object 100 can be placed on the mounting unit 31. The mounting portion 31 is located below the region 21b where the plasma P is generated.

The mounting portion 31 may have an electrode 31a, an insulating ring 31b, and a pedestal 31c.
The electrode 31a can be formed of a conductive material such as metal. The upper surface of the electrode 31a can be a mounting surface on which the processed object 100 is mounted. The electrode 31a can be screwed to, for example, the pedestal 31c. Further, the electrode 31a can incorporate a pickup pin 31a1 (see FIG. 2), a temperature control unit, and the like. A plurality of pickup pins 31a1 may be provided.

The plurality of pickup pins 31a1 have a rod shape and can be provided so as to project from the upper surface of the electrode 31a. The plurality of pickup pins 31a1 can be used when the processed object 100 is delivered. Therefore, the plurality of pickup pins 31a1 can be projected from the upper surface of the electrode 31a and pulled into the inside of the electrode 31a by a drive unit (not shown). The number and arrangement of the plurality of pickup pins 31a1 can be appropriately changed according to the size, the planar shape, and the like of the processed object 100.

The temperature control unit can be, for example, a refrigerant circulation line (flow path), a heater, or the like. The temperature control unit can control, for example, the temperature of the electrode 31a and, by extension, the temperature of the processed object 100 placed on the electrode 31a based on the output from a temperature sensor (not shown).

The insulating ring 31b has a ring shape and can cover the side surface of the electrode 31a. The insulating ring 31b can be formed from a dielectric material such as quartz.
The pedestal 31c can be provided between the electrode 31a and the mounting portion 32a of the support portion 32. The pedestal 31c can be provided to insulate between the electrode 31a and the support portion 32. The pedestal 31c can be formed from a dielectric material such as quartz. The pedestal 31c can be screwed to, for example, the mounting portion 32a of the support portion 32.

The support portion 32 can support the mounting portion 31 in the internal space of the chamber 2. The support portion 32 may extend between the side surface of the chamber 2 and below the mounting portion 31.
The support portion 32 can have a mounting portion 32a, a beam 32b, and a flange 32c. The mounting portion 32a, the beam 32b, and the flange 32c can be formed of, for example, an aluminum alloy or the like.

The mounting portion 32a can be located below the mounting portion 31 in the internal space of the chamber 2. The mounting portion 32a can be provided so that the center of the mounting portion 32a is located on the central axis 2a of the chamber 2. The mounting portion 32a has a cylindrical shape, and a hole 32a1 can be provided on the end surface on the mounting portion 31 side. A hole 32a2 can be provided on the end surface on the side opposite to the mounting portion 31 side. The bus bar 42c, the pipe for the refrigerant, and the like can be connected to the electrode 31a via the hole 32a1.

The holes 32a2 can be used for connecting a bus bar 42c, a pipe for a refrigerant, or the like, or for performing maintenance of the electrode 31a. A mounting portion 31 (pedestal 31c) can be provided on the end surface of the mounting portion 32a on the mounting portion 31 side. Therefore, the planar shape of the mounting portion 32a can be the same as the planar shape of the mounting portion 31. The plane dimension of the mounting portion 32a can be about the same as or slightly larger than the plane dimension of the mounting portion 31.

One end of the beam 32b can be connected to the side surface of the mounting portion 32a. The other end of the beam 32b can be connected to the flange 32c. The beam 32b can extend the internal space of the chamber 2 from the side surface of the chamber 2 toward the central axis 2a of the chamber 2. The beam 32b may have a square cylinder shape. The internal space of the beam 32b can be connected to the external space (atmospheric space) of the chamber 2 via the hole 32c1 provided in the flange 32c. Therefore, the bus bar 42c can come into contact with the atmospheric space. If the internal space of the beam 32b is connected to the external space of the chamber 2, the pressure of the internal space of the beam 32b becomes the same as the pressure of the external space of the chamber 2 (for example, atmospheric pressure). Further, the internal space of the beam 32b can be connected to the internal space of the mounting portion 32a. In this case, the pressure in the internal space of the support portion 32 becomes the same as the pressure in the external space of the chamber 2 (for example, atmospheric pressure).

The flange 32c has a plate shape and can have a hole 32c1 penetrating in the thickness direction. The flange 32c can be attached to the outer wall of chamber 2, for example, screwed to the outer wall of chamber 2.

A hole 2b can be provided on the side surface of the chamber 2. The hole 2b can have a size and shape that allows the mounting portion 31 attached to the mounting portion 32a to pass through. Therefore, the mounting module 3 provided with the mounting portion 31 can be removed from the chamber 2 or the mounting module 3 provided with the mounting portion 31 can be attached to the chamber 2 through the hole 2b.

That is, the mounting portion 32a and the beam 32b provided with the mounting portion 31 can be carried into the inside of the chamber 2 and carried out to the outside of the chamber 2 through the hole 2b. A slider may be provided on the outer wall of the chamber 2 to facilitate the attachment and detachment of the mounting module 3.

The cover 33 can be provided on the end surface of the mounting portion 32a on the side opposite to the mounting portion 31 side. The cover 33 can be screwed to, for example, the mounting portion 32a. By attaching the cover 33 to the attachment portion 32a, the hole 32a2 can be hermetically closed. The shape of the cover 33 is not particularly limited, and may be a dome-shaped cover 33 or a plate-shaped cover 33. The cover 33 can be formed from, for example, an aluminum alloy.

Here, if the support portion 32 has a cantilever structure, a space can be provided below the mounting portion 31 in the internal space of the chamber 2, so that the decompression unit 6 is arranged directly under the mounting portion 31. It becomes possible. If the decompression unit 6 can be arranged directly below the mounting unit 31, the effective exhaust speed is high and it becomes easy to perform axisymmetric exhaust without bias. Further, if the support portion 32 has a cantilever structure, the support portion 32 provided with the mounting portion 31 can be removed from the chamber 2 or the support portion 32 provided with the mounting portion 31 can be removed from the chamber 2 from the horizontal direction. Can be attached to. Therefore, the maintenance of the plasma processing apparatus becomes easier as compared with the case where the mounting portion 31 is fixed to the bottom surface of the chamber 2.

However, the mounting portion 31 is provided with a metal electrode 31a. Further, the mounting unit 31 is also provided with a pickup pin 31a1, a driving unit thereof, a temperature control unit such as a refrigerant circulation line and a heater, and the like. Therefore, the weight of the mounting portion 31 becomes heavy. Since the support portion 32 has a cantilever structure, if the weight of the mounting portion 31 provided on the tip side becomes heavy, the load may be biased and the tip of the beam 32b supporting the mounting portion 31 may bend downward. be. If the tip of the beam 32b bends downward, the mounting portion 31 may tilt. For example, the weight of the mounting portion 31 may be 56 to 70 kgf (kilogram-force). In such a case, the tip of the mounting module 3 may be lowered by about 0.2 mm.

Since the processed material 100 is placed on the mounting portion 31, the mounting surface on which the processed material 100 is placed needs to have an area at least equal to or larger than the area of the main surface of the processed material 100. Therefore, the plane dimension of the mounting portion 31 becomes large. If the mounting portion 31 having a large planar dimension is tilted, the gas flow in the chamber 2 may be disturbed or the plasma density may become non-uniform, resulting in non-uniform processing characteristics.

In this case, if the cross-sectional dimension of the beam 32b supporting the mounting portion 31 is increased in order to suppress the inclination of the mounting portion 31, exhaust is hindered, the effective exhaust speed is lowered, and the effective exhaust speed is not biased. Exhaust may be difficult. In this case, if the number of beams 32b that support the mounting portion 31 is increased, the cross-sectional dimension of one beam 32b can be reduced, so that a decrease in the effective exhaust speed can be suppressed. Further, if the arrangement of the plurality of beams 32b is devised, axisymmetric exhaust can be performed. However, if the number of beams 32b is increased, the size of the portion fixed to the side surface of the chamber 2 becomes large, so that it becomes difficult to attach and detach the support portion 32, and there is a possibility that maintainability is deteriorated.

Therefore, the support portion 32 according to the present embodiment is provided with a beam 32b having a space inside. Then, as described above, the internal space of the beam 32b is connected to the external space of the chamber 2. That is, the pressure in the internal space of the beam 32b is the same as the pressure in the external space of the chamber 2 (for example, atmospheric pressure). Further, the wall thickness of the side portion (upper side portion) of the beam 32b on the mounting portion 31 side is set to t1, and the wall thickness of the side portion (lower side portion) opposite to the mounting portion 31 side of the beam 32b. When the thickness is t2, "t1> t2".

Therefore, when performing plasma treatment, an evenly distributed load corresponding to the difference between the pressure inside the beam 32b and the pressure outside the beam 32b is applied to the upper side portion and the lower side portion of the beam 32b. It will be. In this case, the evenly distributed load applied to the upper side portion and the lower side portion of the beam 32b becomes equal. Therefore, if "t1> t2", the amount of deflection of the upper side portion of the beam 32b is larger than the amount of deflection of the lower side portion of the beam 32b. As a result, the tip of the beam 32b bends upward, so that the downward bending due to the weight of the mounting portion 31 can be offset by the upward bending due to the pressure difference. The specific dimensions of the wall thicknesses t1 and t2 can be appropriately determined by conducting experiments and simulations.

Next, returning to FIG. 1, the power supply unit 4, the power supply unit 5, the decompression unit 6, the gas supply unit 7, the processing state detection unit 8, and the control unit 9 will be described.
The power supply unit 4 can be a so-called high frequency power supply for bias control. That is, the power supply unit 4 can be provided to control the energy of the ions drawn into the processed object 100 on the mounting unit 31.

The power supply unit 4 may have a power supply unit 41 and a matching unit 42.
The power supply 41 can output high frequency power having a frequency suitable for attracting ions (for example, a frequency of 27 MHz to 1 MHz).
The matching section 42 may include a matching circuit 42a, a fan 42b, and a busbar 42c.
The matching circuit 42a can be provided to match the impedance on the power supply 41 side and the impedance on the plasma P side. The matching circuit 42a can be electrically connected to the power supply 41 and the electrode 31a via the bus bar (wiring member) 42c. That is, the power supply 41 can be electrically connected to the electrode 31a provided on the mounting portion 31 via the bus bar 42c.
The fan 42b can send air to the inside of the support portion 32. The fan 42b can be provided to cool the bus bar 42c and the matching circuit 42a provided inside the support portion 32.

Further, the matching portion 42 can be provided on the flange 32c of the support portion 32. If the matching portion 42 is provided on the flange 32c, the mounting module 3 is mounted when the mounting module 3 is removed from the chamber 2 (main body portion 21) or the mounting module 3 is mounted on the chamber 2 (main body portion 21). The module 3 and the matching portion 42 can be moved integrally. Therefore, it is possible to improve maintainability.
Further, the internal space of the beam 32b is connected to the external space of the chamber 2 (main body portion 21) via the matching portion 42. Therefore, the pressure in the internal space of the beam 32b can be the same as the pressure in the space outside the chamber 2 (for example, atmospheric pressure).

The power supply unit 5 can be a high frequency power supply for generating plasma P. That is, the power supply unit 5 can be provided to generate high-frequency discharge inside the chamber 2 to generate plasma P.
In the present embodiment, the power supply unit 5 is provided on the surface of the window 23 opposite to the mounting unit 31 side, which is outside the chamber 2, and plasma P is generated inside the chamber 2. It becomes the generation part.

The power supply unit 5 may have an electrode 51, a power supply 52, a matching circuit 53, and a Faraday shield 54.
The electrode 51 is outside the chamber 2 and can be provided above the window 23. The electrode 51 may have a plurality of conductor portions for generating an electromagnetic field and a plurality of capacitance portions (capacitors).
The power supply 52 can output high frequency power having a frequency of about 100 KHz to 100 MHz. In this case, the power supply 52 can output high frequency power having a frequency suitable for generating plasma P (for example, a frequency of 13.56 MHz). Further, the power supply 52 may change the frequency of the high frequency power to be output.

The matching circuit 53 can be provided to match the impedance on the power supply 52 side and the impedance on the plasma P side. The matching circuit 53 can be electrically connected to the power supply 52 and the electrode 51 via the wiring 55. The matching circuit 53 can also be electrically connected to the power supply 52 and the electrode 51 via a bus bar.

The Faraday shield 54 can be provided between the window 23 and the electrode 51. The Faraday shield 54 has a plate shape and can be formed of a conductive material such as metal. The Faraday shield 54 can have a plurality of slits radiating from the center. Further, an insulating film using an insulating material can be provided on the surface of the Faraday shield 54 on the electrode 51 side. The portion of the Faraday Shield 54 formed of the conductive material can be grounded.

The plasma processing apparatus 1 illustrated in FIG. 1 is a dual-frequency plasma processing apparatus having an inductively coupled electrode at the upper part and a capacitively coupled electrode at the lower part.
However, the method of generating plasma is not limited to the example.
The plasma processing apparatus 1 may be, for example, a plasma processing apparatus using inductively coupled plasma (ICP: Inductively Coupled Plasma), a plasma processing apparatus using capacitively coupled plasma (CCP: Capacitively Coupled Plasma), or the like.

The decompression unit 6 is located below the mounting unit 31, and can depressurize the inside of the chamber 2 so that the pressure becomes a predetermined pressure.
The decompression unit 6 may include a pump 61 and a valve 62.
The pump 61 can be provided outside the chamber 2. The pump 61 can be connected to the hole 21a1 provided in the bottom plate 21a of the chamber 2. The pump 61 can exhaust the gas inside the chamber 2. The pump 61 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 valve 62 can have a valve body 62a and a drive unit 62b.
The valve body 62a has a plate shape and can be provided inside the chamber 2. The valve body 62a can face the hole 21a1. The planar dimension of the valve body 62a can be made larger than the planar dimension of the intake port 61a. When the valve body 62a is viewed from the direction of the central axis 2a, the valve body 62a can cover the intake port 61a of the pump 61.

The drive unit 62b can change the position of the valve body 62a in the direction of the central axis 2a of the chamber 2 (main body unit 21). That is, the drive unit 62b can raise the valve body 62a or lower the valve body 62a. The drive unit 62b may include a shaft 62a1 connected to the valve body 62a and a control motor (for example, a servomotor or the like) for moving the shaft 62a1. The valve 62 can be a so-called poppet valve.

Here, when the position of the valve body 62a changes inside the chamber 2, the distance between the valve body 62a and the bottom plate 21a of the chamber 2 changes. The space between the valve body 62a and the bottom plate 21a of the chamber 2 serves as an exhaust flow path. Therefore, when the dimensions of this portion are changed, the conductance changes, so that the displacement, the exhaust speed, and the like can be controlled. The control unit 9 can change the position of the valve body 62a by controlling the drive unit 62b based on the output of a vacuum gauge (not shown) for detecting the internal pressure of the chamber 2, for example. The vacuum gauge can be a diaphragm type capacitance manometer or the like.

The gas supply unit 7 can supply the gas G to the region 21b in which the plasma P is generated inside the chamber 2.
The gas supply unit 7 can have a gas storage unit 71, a gas control unit 72, and an on-off valve 73. The gas storage unit 71, the gas control unit 72, and the on-off valve 73 can be provided outside the chamber 2.
The gas storage unit 71 stores the gas G and can supply the stored gas G to the inside of the chamber 2. The gas storage unit 71 can be, for example, a high-pressure cylinder that stores the gas G. The gas storage unit 71 and the gas control unit 72 can be connected via piping.

The gas control unit 72 can control the flow rate, pressure, and the like of the gas G supplied from the gas storage unit 71 to the inside of the chamber 2. The gas control unit 72 may be, for example, an MFC (Mass Flow Controller) or the like. The gas control unit 72 and the on-off valve 73 can be connected via piping.

The on-off valve 73 can be connected to the gas supply port 22b provided in the chamber 2 via a pipe. A plurality of gas supply ports 22b may be provided so that the gas G can be evenly supplied to the region 21b where the plasma P is generated from a plurality of directions. The on-off valve 73 can control the supply and stop of the gas G. The on-off valve 73 may be, for example, a 2-port solenoid valve or the like. The gas control unit 72 can also have the function of the on-off valve 73.

When the gas G is excited and activated by the plasma P, desired radicals and ions can be generated. For example, when the plasma treatment is an etching treatment, the gas G can generate radicals and ions capable of etching the exposed surface of the processed object 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 processing state detection unit 8 can detect the state of the processed object 100 based on the optical change that occurs during the plasma processing. For example, the processing state detection unit 8 can detect the end point of plasma processing.
The processing state detection unit 8 can include an optical path changing unit 81 and a detection unit 82.

The optical path changing portion 81 can be provided inside the window 23. The optical path changing portion 81 has a direction perpendicular to the direction from the window 23 toward the mounting portion 31 (thickness direction of the window 23) and a direction orthogonal to the direction from the window 23 toward the mounting portion 31 (direction orthogonal to the thickness direction of the window 23). The optical path of the incident light is changed between and.
For example, the optical path changing portion 81 may be locally provided inside the window 23 and may have a surface (reflection surface) inclined with respect to the central axis 2a of the chamber 2.

FIG. 3 is a schematic cross-sectional view for illustrating the optical path changing portion 81.
The optical path changing portion 81 illustrated in FIG. 3 can be a concave portion of the window 23 that opens on the surface opposite to the mounting portion 31 side. For example, the bottom surface of the recess, which is the optical path changing portion 81, is a flat surface, and the bottom surface is a surface 81a, which is a reflective surface. The angle between the surface 81a and the central axis 2a of the chamber 2 can be 45 °. The outer shape of the recess may be, for example, a cylinder or a polygonal prism.

As shown in FIG. 3, the optical path changing unit 81 can reflect the incident light La so that the angle between the optical path of the incident light La and the optical path of the emitted light Lb is 90 °. That is, the angle of incidence of the light directed from the detection unit 82 toward the surface 81a on the surface 81a can be 45 °. The reflection angle can be 45 °.
In addition, in FIG. 3, the case where the light is incident from the thickness direction of the window 23 (the case where the light is incident from the mounting portion 31 side to the optical path changing portion 81) is illustrated, but the inspection light is the side surface side of the window 23 (the case where the light is incident). Even when the light is incident on the optical path changing portion 81 from the peripheral end surface side), the traveling direction of the inspection light is changed by the optical path changing portion 81. Then, the traveling direction of the inspection light emitted from the optical path changing unit 81 and reflected by the processed object 100 is also changed by the optical path changing unit 81 in the same manner as the incident light La.

As described above, the optical path changing portion 81 illustrated in FIG. 3 is a recess. The inside of the optical path changing portion 81 may be a space, or may be filled with a gas, a liquid, or a solid. Further, a film containing a material having a high reflectance (for example, a film containing titanium oxide) can be formed on the surface 81a. When the inside of the optical path changing portion 81 is filled with a gas, a liquid, or a solid, or when a film is provided on the surface 81a, it is preferable to use a gas, a liquid, or a solid having an insulating property. By doing so, it is possible to suppress the optical path changing unit 81 from affecting the electromagnetic field formed by the power supply unit 5.
Further, if the surface 81a has irregularities, light is scattered by the irregularities, so it is preferable to increase the flatness of the surface 81a. For example, the surface roughness of the surface 81a can be set to Ra 0.02 or less by optical polishing.

4 (a) and 4 (b) are schematic cross-sectional views for exemplifying a modified example of the optical path changing portion.
As shown in FIG. 4A, the optical path changing portion 81b having a small depth dimension d can be used. If the depth dimension d is small, the length of the cutting tool used for cutting the concave portion serving as the optical path changing portion 81b can be shortened. The rigidity of the cutting tool can be increased by the shorter length of the cutting tool. Therefore, the vibration of the cutting tool is reduced, and the flatness of the bottom surface (surface 81ba) of the concave portion serving as the optical path changing portion 81b is improved. For example, when the surface 81ba is circular, the depth dimension d is preferably 0.5 times or more and 1.0 times or less the diameter thereof. When the surface 81ba is a quadrangle, it is preferably 0.5 times or more and 1.0 times or less the diameter of the inscribed circle.

Further, as shown in FIG. 4B, the optical path changing portion 81c having a large area of the bottom surface (surface 81ca) can be used. By increasing the area of the surface 81ca, a cutting tool having a large cross-sectional area can be used. The rigidity of the cutting tool can be increased by the larger the cross-sectional area of the cutting tool. Therefore, the vibration of the cutting tool is reduced, and the flatness of the bottom surface (surface 81ca) of the concave portion serving as the optical path changing portion 81c is improved.
The depth of the recess may be reduced and the area of the bottom surface of the recess may be increased. By doing so, the flatness of the bottom surface can be further improved. Further, since optical polishing can be easily performed, it becomes easier to set the flatness of the bottom surface to a desired value.

Here, the cross-sectional area of the optical path changing portion 81 (see “D” in FIG. 6) in the direction orthogonal to the central axis 2a is the area of the surface of the window 23 opposite to the mounting portion 31 side. It is preferably 1.95% or less. Alternatively, it is preferable that the load applied to the optical path changing portion 81 is 9.8% or less of the allowable load of the window 23. If the load applied to the optical path changing portion 81 is about this level, the durability of the window 23 having the optical path changing portion 81 can be regarded as substantially the same as the durability of the window without the optical path changing portion 81. That is, in this way, the strength (vacuum resistant strength) of the window 23 can be maintained.

Further, the cross-sectional area of the optical path changing portion 81 (see “D” in FIG. 6) in the direction orthogonal to the central axis 2a is 0 in the area of the surface of the window 23 opposite to the mounting portion 31 side. It is more preferably 5.5% or less. Alternatively, it is more preferable that the load applied to the optical path changing portion 81 is 5.0% or less of the allowable load of the window 23. By doing so, since the change in the capacitance of the window 23 can be made slight, it is possible to suppress the optical path changing unit 81 from affecting the electromagnetic field formed by the power supply unit 5. ..

FIG. 5 is a schematic cross-sectional view for exemplifying another modification of the optical path changing portion.
The optical path changing portion 81d illustrated in FIG. 5 is a recess having a polygonal columnar shape (for example, a square columnar shape) having a flat side surface 81da. The side surface 81da of the optical path changing portion 81d is inclined at an angle of 45 ° with respect to the upper surface of the window 23 (the surface opposite to the mounting portion 31 side). By doing so, the incident light La incident on the side surface 81da from the direction orthogonal to the upper surface of the window 23 can be used as the emitted light Lb reflected in the direction parallel to the upper surface of the window 23. In this case, it is easy to increase the area of the side surface of the recess as compared with the bottom surface of the recess, so that optical polishing can be easily performed.

Here, a part of the light incident on the inside of the window 23 from the surface of the window 23 on the mounting portion 31 side is reflected inside the window 23 and emitted to the outside from the side surface (peripheral end surface) of the window 23. Therefore, the detection unit 82 can also detect the light emitted to the outside from the side surface of the window 23. However, in this way, the intensity of the light incident on the detection unit 82 becomes the average value of the intensity of the light in a relatively wide range, so that it becomes difficult to detect a slight change in the surface of the processed object 100. ..

In recent years, the processed portion has become finer, and for example, the aperture ratio of formed irregularities and holes may be 1% or less. In such a case, the amount of the substance to be removed is small, so that the amount of change in light is small. Therefore, when light emission in a wide range is detected, it becomes more difficult to detect a slight change in the surface of the processed product 100.

Further, as described above, an electrode 51, a Faraday shield 54, and the like are provided on the window 23. Therefore, if the light emitted in the thickness direction of the window 23 is detected, the electrode 51, the Faraday shield 54, and the like may interfere with the detection of the light at an appropriate position.

As described above, the optical path changing portion 81 can have a small cross-sectional area and can be provided at an arbitrary position on the window 23. Therefore, it is possible to detect a change in light in a narrow region (detection region) at an appropriate position. As a result, even if it is a fine process, the end point of the plasma process can be detected with high accuracy, and by extension, the fine process can be performed with high accuracy.

Further, since the angle between the optical path of the incident light and the optical path of the emitted light can be set to 90 °, the detection unit 82 can be arranged on the side surface side of the window 23. Therefore, the detection unit 82 can be arranged at an appropriate position regardless of the shape and arrangement of the electrode 51, the Faraday shield 54, and the like.

The detection unit 82 is provided on the side surface side of the window 23, and can be provided at a position facing the surface 81a of the optical path changing unit 81.
If the optical path changing unit 81 is provided, a part of the light generated inside the chamber 2 is reflected on the surface 81a of the optical path changing unit 81 and incident on the detection unit 82. Therefore, the detection unit 82 can have a light receiving unit. For example, the detection unit 82 can detect the state of the processed object 100 (for example, the end point of plasma processing) based on the change in the wavelength of the light incident on the light receiving unit via the optical path changing unit 81.

The "position facing the surface 81a of the optical path changing portion 81" refers to the light incident on the inside of the window 23 from the surface of the window 23 on the mounting portion 31 side (incident light La) of the optical path changing portion 81. This is a position where the detection unit 82 can detect the light reflected by the surface 81a (emitted light Lb).

Further, for example, the detection unit 82 may have a light emitting unit and a light receiving unit. The light projecting unit can irradiate the surface of the processed object 100 with inspection light via the optical path changing unit 81. The light receiving unit can receive the interference light of the light reflected on the surface of the processed object 100 and directed to the light receiving unit via the optical path changing unit 81 and the light emitted from the light projecting unit. For example, the detection unit 82 irradiates the surface of the processed object 100 with light through the surface 81a of the optical path changing unit 81. The light reflected on the surface of the processed object 100 and further reflected on the surface 81a of the optical path changing portion 81 is incident on the detection unit 82.
In this case, the detection unit 82 can detect the state of the processed object 100 (for example, the end point of the plasma processing) based on the change in the interference light.

The detection unit 82 is not limited to the one illustrated, and may be any as long as it can detect an optical change. For example, the detection unit 82 may further include a spectroscope. If a spectroscope is provided, light having a predetermined wavelength can be extracted, so that the detection accuracy can be improved.

Further, in the case of the detection unit 82 having a light projecting unit and a light receiving unit, it is preferable that most of the light reflected on the surface of the processed object 100 is incident on the surface 81a of the optical path changing unit 81. That is, it is preferable that the optical axis of the inspection light bent by the optical path changing portion 81 and the optical axis of the inspection light reflected on the surface of the processed object 100 are substantially the same. For this purpose, it is preferable that the window 23 and the mounting portion 31 are substantially parallel to each other. However, as described above, when the support portion 32 that supports the mounting portion 31 has a cantilever structure, the mounting portion 31 may be tilted. Therefore, when the detection unit 82 having the light projecting unit and the light receiving unit and the mounting unit 31 having the cantilever structure are used, the thickness of the beam 32b is larger than the wall thickness (t2) of the lower side portion of the beam 32b. It is preferable to increase the wall thickness (t1) of the upper side portion (t1> t2). If "t1> t2", it becomes easy to make the window 23 and the mounting portion 31 substantially parallel, so that the optical axis of the inspection light bent by the optical path changing portion 81 and the surface of the processed object 100 are reflected. The optical axis of the inspection light can be made to be substantially the same as that of the optical axis.

Further, as shown in FIG. 1, the optical path changing unit 81 and the detection unit 82 can also be connected via the light guide unit 83. In this case, the light guide unit 83 faces the surface 81a of the optical path changing unit 81. The light guide unit 83 may be, for example, an optical fiber or the like. The light guide unit 83 is not always necessary, and the detection unit 82 may be provided close to the side surface of the window 23. However, if the light guide unit 83 is provided, it becomes easy to provide the detection unit 82 at a desired position.

FIG. 6 is a schematic plan view for exemplifying a flat surface provided on the side surface of the window.
As shown in FIG. 6, a flat surface 23a can be provided on the side surface of the window 23 facing the detection unit 82 or the light guide unit 83. When the light guide unit 83 is provided, the light guide unit 83 can be provided between the surface surface 23a on the side surface of the window 23 and the detection unit 82. By doing so, it is possible to facilitate the optical connection between the detection unit 82 or the light guide unit 83 and the window 23.

Further, if the surface 23a has irregularities, light is scattered by the irregularities, so it is preferable to increase the flatness of the surface 23a as in the surface 81a. For example, the surface roughness of the surface 23a can be set to Ra 0.02 or less by optical polishing.
The surface 23a and the surface 81a of the optical path changing portion 81 may be provided so as to be orthogonal to the axis 2a and parallel to each other in the vertical direction of the paper surface in FIG. By doing so, it is possible to facilitate the optical connection between the detection unit 82 or the light guide unit 83 and the optical path changing unit 81.

Further, the light guide unit 83 can have a plurality of optical fibers. The detection unit 82 can have a plurality of spectroscopes. Then, one optical fiber can be connected to one spectroscope. By doing so, the above-mentioned interference light can be easily detected.

Further, a plurality of optical path changing portions 81 may be provided. If a plurality of optical path changing units 81 are provided, the state of processing at a plurality of locations can be known, and if the optical path changing unit 81 used for detection is selected, a plurality of optical path changing units 81 can be selected without increasing the number of detection units 82. It is possible to know the processing status at the location of.

The control unit 9 may include a calculation unit such as a CPU (Central Processing Unit) and a storage unit such as a memory.
The control unit 9 can control the operation of each element provided in the plasma processing device 1 based on the control program stored in the storage unit. For example, the control unit 9 can end the plasma processing based on the output from the processing state detection unit 8 (detection unit 82).

7 (a) and 7 (b) are schematic cross-sectional views for exemplifying the optical path changing portion 181 according to another embodiment.
As shown in FIGS. 7A and 7B, the optical path changing portion 181 can be provided inside the window 23. The optical path changing portion 181 has a flat end surface 181a, and the angle between the end surface 181a and the central axis 2a of the chamber 2 can be 45 °.

As shown in FIG. 7A, the optical path changing portion 181 can be embedded inside the window 23. For example, the optical path changing portion 181 can be embedded when forming the window 23. For example, the optical path changing portion 181 can be formed by irradiating the window 23 with a laser and processing the inside of the window 23.

As shown in FIG. 7B, the recess 181b can be provided in the window 23, and the optical path changing portion 181 can be provided inside the recess 181b.
The optical path changing portion 181 is preferably formed of a material having high reflectance and insulating properties. For example, the optical path changing portion 181 may be a processed inside of the window 23, a film containing titanium oxide, or the like. If the optical path changing unit 181 has an insulating property, it is possible to suppress the optical path changing unit 181 from affecting the electromagnetic field formed by the power supply unit 5.

FIG. 8 is a schematic cross-sectional view for illustrating the plasma processing apparatus 101 according to another embodiment.
As shown in FIG. 8, the plasma processing apparatus 101 includes a chamber 102, a mounting unit 103, a power supply unit 4, a power supply unit 5, a decompression unit 106, a gas supply unit 7, a processing state detection unit 8, and a control unit 109. Can be provided. Also in the plasma processing device 101, the power supply unit 5 is a plasma generation unit that generates plasma P inside the chamber 102.

The chamber 102 can have an airtight structure capable of maintaining an atmosphere depressurized below atmospheric pressure.
The chamber 102 can have a body 102a and a window 23.
The main body portion 102a may have a top plate, a bottom plate, and a substantially cylindrical side portion integrated. The main body 102a can be formed of, for example, a metal such as an aluminum alloy. Further, the main body portion 102a can be grounded. Inside the main body 102a, a region 102b where plasma P is generated is provided. The main body 102a may be provided with a carry-in / carry-out port 102c for carrying in / out the processed material 100. The carry-in / carry-out port 102c can be airtightly closed by the gate valve 102d.

The mounting portion 103 can be provided inside the chamber 102 (main body portion 102a) and on the bottom surface of the main body portion 102a. The mounting portion 103 can have an electrode 103a, a pedestal 103b, and an insulating ring 103c. The inside of the mounting portion 103 can be connected to an external space (atmospheric space).

The electrode 103a can be provided below the region 102b where the plasma P is generated. The upper surface of the electrode 103a can be a mounting surface on which the processed object 100 is mounted. The electrode 103a can be formed of a conductive material such as metal. Further, similarly to the electrode 31a described above, the electrode 103a can incorporate a plurality of pickup pins, a temperature control unit, and the like.

The pedestal 103b can be provided between the electrode 103a and the bottom surface of the main body 102a. The pedestal 103b can be provided to insulate between the electrode 103a and the main body 102a. The pedestal 103b can be formed from a dielectric material such as quartz.

The insulating ring 103c has a ring shape and can be provided so as to cover the side surface of the electrode 103a and the side surface of the pedestal 103b. The insulating ring 103c can be formed from a dielectric material such as quartz.

The above-mentioned power supply unit 4 can also be provided in the plasma processing apparatus 101 according to the present embodiment. As described above, the power supply unit 4 can be a high frequency power supply for so-called bias control. Further, the matching circuit 42a can be electrically connected to the power supply 41 and the electrode 103a via the bus bar 42c. Since the inside of the mounting portion 103 is connected to the atmospheric space, the bus bar 42c can be in contact with the atmospheric space.

The plasma processing apparatus 101 can also be a dual frequency plasma etching apparatus having an inductively coupled electrode at the upper part and a capacitively coupled electrode at the lower part. However, the method of generating plasma is not limited to the example.
The plasma processing apparatus 101 may be, for example, a plasma processing apparatus using inductively coupled plasma (ICP: Inductively Coupled Plasma), a plasma processing apparatus using capacitively coupled plasma (CCP: Capacitively Coupled Plasma), or the like.

The depressurizing unit 106 may have a pump 106a and a pressure control unit 106b.
The pressure reducing unit 106 can reduce the pressure so that the inside of the chamber 102 has a predetermined pressure. The pump 106a can be, for example, a turbo molecular pump or the like. As a back pump, a roots type dry pump can also be connected to a turbo molecular pump. The pump 106a and the pressure control unit 106b can be connected via piping.

The pressure control unit 106b can control the internal pressure of the chamber 102 to be a predetermined pressure based on the output of a vacuum gauge or the like (not shown) that detects the internal pressure of the chamber 102. The vacuum gauge can be a diaphragm type capacitance manometer or the like. The pressure control unit 106b can be, for example, an APC (Auto Pressure Controller) or the like. The pressure control unit 106b can be connected to the exhaust port 102e provided in the main body unit 102a via a pipe.

The control unit 109 may include a calculation unit such as a CPU and a storage unit such as a memory. The control unit 109 can control the operation of each element provided in the plasma processing device 101 based on the control program stored in the storage unit. For example, the control unit 109 can end the plasma processing based on the output from the processing state detection unit 8 (detection unit 82).
Since the plasma processing apparatus 101 according to the present embodiment is also provided with the processing state detection unit 8, the above-mentioned effect can be enjoyed.

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 shapes, materials, arrangements, and the like of the components included in the plasma processing devices 1 and 101 are not limited to those illustrated, and can be appropriately changed.
Further, 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, 2a central axis, 3 mounting module, 4 power supply section, 5 power supply section, 6 decompression section, 7 gas supply section, 8 processing status detection section, 9 control section, 23 windows, 31 mounting Section, 81 Optical path change section, 81a surface, 82 Detection section, 83 Light guide section, 100 Processed object, 101 Plasma processing device, 102 chamber, 103 Mounting section, 106 Decompression section

Claims (8)

A chamber that can maintain an atmosphere that is decompressed from atmospheric pressure,
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 provided in the chamber and facing the above-mentioned mounting portion,
A plasma generating portion that is provided on the surface of the window opposite to the previously described placing portion side of the outside of the chamber and is capable of generating plasma inside the chamber.
An optical path changing portion locally provided inside the window and having a surface inclined with respect to the central axis of the chamber.
A detection unit provided on the side surface side of the window and facing the surface of the optical path changing unit,
Equipped with
The detection unit irradiates the surface of the processed object with light through the surface of the optical path changing portion, is reflected by the surface of the processed object, and further reflected light is incident on the surface of the optical path changing portion. The detection unit is a plasma processing device that detects the end point of plasma processing from the interference light. The plasma processing apparatus according to claim 1, wherein the surface of the optical path changing portion is a flat surface, and the angle between the surface and the central axis of the chamber is 45 °. The plasma processing apparatus according to claim 2, wherein the angle of incidence of light from the detection unit toward the surface on the surface is 45 °, and the angle of reflection is 45 °. The plasma processing apparatus according to any one of claims 1 to 3, wherein the optical path changing portion is a recess opened in a surface of the window opposite to the previously described placement portion side. The plasma processing apparatus according to claim 4, wherein the load applied to the optical path changing portion is 5.0% or less of the allowable load of the window. A flat surface is provided on the side surface of the window facing the detection unit.
The plasma processing apparatus according to any one of claims 1 to 5, further comprising a light guide unit provided between the flat surface and the detection unit. The light guide portion has a plurality of optical fibers and has a plurality of optical fibers.
The detector has a plurality of spectroscopes and has a plurality of spectroscopes.
The plasma processing apparatus according to claim 6 , wherein one optical fiber is connected to one spectroscope. The internal space of the chamber is further provided with a support for supporting the above-mentioned placement.
The support portion is
The mounting part where the above-mentioned placement part is provided, and
A beam that extends inside the chamber and has a space inside that is connected to the mounting portion at one end and connected to the space outside the chamber.
Have,
A claim that satisfies the following equation when the wall thickness of the side portion of the beam on the front-stated placement side is t1 and the wall thickness of the side of the beam opposite to the front-statement placement side is t2. Item 6. The plasma processing apparatus according to any one of Items 2 to 7.
t1> t2

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