WO2010016423A1

WO2010016423A1 - Dielectric window, dielectric window manufacturing method, and plasma treatment apparatus

Info

Publication number: WO2010016423A1
Application number: PCT/JP2009/063572
Authority: WO
Inventors: 清隆石橋
Original assignee: 東京エレクトロン株式会社
Priority date: 2008-08-08
Filing date: 2009-07-30
Publication date: 2010-02-11
Also published as: TW201031283A; JP2010041014A

Abstract

A dielectric window manufacturing method, a dielectric window, and a plasma treatment apparatus using the dielectric window with which adhesion between an antenna and the dielectric window is improved, and plasma density distribution is stabilized by preventing abnormal electrical discharge. When the dielectric window (3) is installed in the plasma treatment apparatus (1) and there is no pressure difference between the inside and outside of the dielectric window (3), the side positioned on the outside of the plasma treatment chamber (1) is a convex curved surface. The dielectric window (3) flexes to become concave toward the inside of the plasma treatment chamber (1) and the side positioned on the outside of the plasma treatment chamber (1) becomes flat when the inside of the plasma treatment apparatus (1) is in a vacuum state in which a plasma can be generated.

Description

Dielectric window, method of manufacturing dielectric window, and plasma processing apparatus

The present invention relates to a dielectric window, a method for manufacturing the dielectric window, and a plasma processing apparatus using the dielectric window.

Plasma treatment is widely used in the manufacture of many semiconductor devices such as integrated circuits, liquid crystal circuit boards, and solar cells. Plasma processing is used for deposition of thin films such as Si and etching processes during semiconductor manufacturing. However, in order to develop and manufacture higher performance and higher performance devices, for example, it is required to support ultra-fine processing technology. For this reason, a microwave plasma processing apparatus that can stably generate high-density plasma (low-pressure high-density plasma) in a high-vacuum state with low pressure has attracted attention.

The microwave plasma processing apparatus is a plasma processing apparatus that generates plasma by ionizing a gas by microwave energy. The microwave is supplied from the slot plate of the antenna through the waveguide. Then, the light passes through a dielectric window (top plate) disposed in the upper opening of the plasma processing container (chamber) and is radiated into the plasma processing chamber. The dielectric window is formed of a dielectric material that can transmit microwaves.

In the microwave plasma processing apparatus, the temperature of the dielectric window is required because the dielectric window becomes high temperature during plasma processing and the plasma generation state tends to become unstable.

By the way, there is known a plasma processing apparatus in which an optimum microwave resonance region is formed in a dielectric window under a wide plasma generation condition, and stable plasma generation is possible (see Patent Document 1).

According to this technique, a ring-shaped protrusion is provided on the lower surface of the dielectric window, and the radial thickness of the dielectric window is continuously changed in a tapered shape. As a result, one dielectric window also serves as many types of dielectric windows having various thicknesses, and enables microwave resonance in the dielectric window under any plasma generation conditions. .

Japanese Patent Laid-Open No. 2005-100931

In this technology, the shape of the dielectric window is devised to optimize the propagation state of microwaves in the dielectric window under various plasma generation conditions. However, this technique does not take into consideration the control of the propagation state of the microwave until the microwave is introduced into the dielectric window.

In the microwave plasma processing apparatus, when the inside of the plasma processing container is in a reduced pressure atmosphere, the dielectric window may be deformed due to a pressure difference between the inside of the plasma processing container and the outside. For this reason, a gap is generated between the antenna and the dielectric window, and the introduction of microwaves into the plasma processing container may vary. In addition, this gap may change the thermal conductivity (cooling efficiency) in the vicinity of the dielectric window, the temperature of the dielectric window becomes nonuniform, and the electromagnetic field distribution in the dielectric window may change. As a result, the plasma density distribution (plasma generation state) may become unstable.

The microwave propagates from the waveguide to the antenna slot plate, the cooling jacket located above the antenna, and the like as a transmission path. In this case, if the gap between the transmission lines (slow wave plate and slot plate, antenna and cooling jacket, etc.) becomes large, the propagation of microwaves in the antenna may cause a potential difference between the transmission lines and cause abnormal discharge. It was.

In addition, since the slow wave plate and the dielectric window are both made of a dielectric material and the slot plate is made of metal, a difference in thermal expansion occurs between the members as the temperature rises. For example, when the slow wave plate and the dielectric window are made of alumina (Al ₂ O ₃ ) and the slot plate is made of copper (Cu), the slot plate thermally expands more than the dielectric window and the slow wave plate. .

In the microwave plasma processing apparatus, the slot plate is placed in a state of being sandwiched between a dielectric window provided on the ceiling and a slow wave plate. If the slot plate is fixed to the cooling jacket by screws or the like at the outer peripheral portion thereof, it cannot thermally expand in the radial direction. For this reason, even if the slot plate is planar before the plasma processing, the slot plate is deformed while expanding between the slow wave plate and the dielectric window as the temperature rises due to the plasma processing. As a result, the position of the slot plate fluctuated, and the propagation of microwaves was uneven. In addition, air gaps are created between the slot plate and slow wave plate, between the slot plate and dielectric window, between the cooling jacket and slow wave plate, and abnormal discharge is generated at sites with high electric field strength during microwave propagation in the antenna. There was a case.

Furthermore, the contact resistance during heat conduction between the members becomes non-uniform due to these gaps, resulting in variations in thermal conductivity, and it becomes difficult to control the temperature of each member appropriately even by the cooling jacket. It was.

The present invention has been made in view of such circumstances, and its purpose is to prevent abnormal discharge by improving the adhesion between the antenna and the dielectric window, and to distribute the electromagnetic field in the dielectric window, That is, it is an object to provide a dielectric window capable of stabilizing the plasma density distribution, a method for manufacturing the dielectric window, and a plasma processing apparatus using the dielectric window.

In order to achieve the above object, a method of manufacturing a dielectric window according to the first aspect of the present invention includes:
It is used in a plasma processing apparatus for generating plasma in a plasma processing container using microwaves and performing plasma processing on an object to be processed, and the inside of the plasma processing container can be sealed in a vacuum state capable of generating plasma. A method of manufacturing a dielectric window that propagates the microwave and transmits the microwave into the plasma processing container,
An installation step of installing a dielectric plate in a jig that can be in a vacuum state inside;
By evacuating and depressurizing the inside of the jig by a vacuum depressurization means, a vacuum state similar to that of the plasma processing container is generated, a pressure difference is generated with the dielectric plate as a boundary, and the dielectric plate is placed inside the jig. A differential pressure step that deforms to become convex toward the surface,
A single-side flattening step of flattening one side of the dielectric plate located outside the jig, while maintaining a pressure difference with the dielectric plate as a boundary;
It is characterized by providing.

The dielectric window according to the second aspect of the present invention is:
A dielectric window obtained by the dielectric window manufacturing method according to the first aspect of the present invention,
When the dielectric window is installed in the plasma processing apparatus, when there is no pressure difference between the inside and the outside of the dielectric window, one surface located outside the plasma processing container is a curved surface protruding outward. ,
The dielectric window is bent so as to be convex toward the inside of the plasma processing container when the inside of the plasma processing container is in a vacuum state in which plasma can be generated, and is positioned outside the plasma processing container. It is characterized in that one side to be flattened.

Preferably, the dielectric window has an axisymmetric shape with a central portion being the most convex.

A plasma processing apparatus according to a third aspect of the present invention provides:
A plasma processing apparatus for generating plasma in a plasma processing container using a microwave and performing plasma processing on an object to be processed,
A microwave source for generating the microwave;
A waveguide for transmitting the microwave;
An antenna that radiates the microwave transmitted from the microwave source through the waveguide;
A dielectric window that propagates the microwave radiated from the antenna and transmits the microwave into the plasma processing container,
The dielectric window includes the dielectric window.

Preferably, the antenna is disposed so as to overlap one side of the dielectric window located outside the plasma processing vessel.

Preferably, the antenna includes a slot plate and a slow wave plate disposed adjacent to the slot plate, and the slot plate is supported by a support member so as to be deformable in a plane direction.

Preferably, the antenna includes a slot plate and a slow wave plate disposed adjacent to the slot plate, and in the slot plate, the plurality of pairs of slots are respectively substantially on the concentric circles of the plurality of concentric circles. Each pair of slots may be formed so as to be orthogonal to each other.

Preferably, a cooling means for cooling the antenna is provided so as to be in contact with and overlap one side of the antenna.

Preferably, the slot plate is made of metal, and the slow wave plate is made of a dielectric material.

According to the dielectric window of the present invention, the method of manufacturing the dielectric window, and the plasma processing apparatus using the dielectric window, by improving the adhesion between the antenna and the dielectric window, preventing abnormal discharge, The plasma density distribution can be stabilized.

It is a side view of the dielectric material window concerning the embodiment of the present invention. FIG. 1B is a side view showing the dielectric window shown in FIG. 1A and the conventional dielectric window (shown by a broken line) in an overlapped manner so that they can be compared. FIG. 1B is a cross-sectional view of a dielectric plate before forming a curved surface in the dielectric window shown in FIG. 1A. It is a section schematic diagram explaining a manufacturing method of a dielectric window concerning an embodiment of the present invention. It is another cross-sectional schematic explaining the manufacturing method of the dielectric material window which concerns on embodiment of this invention. 1 is an overall cross-sectional view of a plasma processing apparatus according to an embodiment of the present invention. It is a top view which shows an example of the slot plate which concerns on embodiment of this invention. It is the elements on larger scale of FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals.

The present embodiment relates to a dielectric window manufacturing method according to the first aspect of the present invention, a dielectric window according to the second aspect of the present invention, and a microwave plasma processing apparatus according to the third aspect of the present invention. (Hereinafter simply referred to as “plasma processing apparatus”). The dielectric window of this embodiment has a curved surface that is convex on one side. The curved surface is formed in an axisymmetric shape with high accuracy so that the radius of curvature has a predetermined size. Furthermore, the curved surface is polished smoothly.

FIG. 1A is a side view of a dielectric window 3 according to an embodiment of the present invention. The dielectric window corresponds to the dielectric window 3 according to the second aspect of the present invention. Further, the dielectric window corresponds to the dielectric window 3 manufactured by the dielectric window manufacturing method according to the first aspect of the present invention.
FIG. 1B is a side view showing the dielectric window 3 shown in FIG. 1A and a prior art dielectric window 30 (shown by broken lines) in an overlapping manner so that they can be compared.

In the following description, when the dielectric window 3 is installed in the plasma processing apparatus 1, one side of the dielectric window 3 located outside the chamber (plasma processing container) 2 is defined as an upper surface 3f. Further, in the dielectric window 3, a surface located inside the chamber 2 is a lower surface 3 b. As will be described later, the chamber 2 has a bottomed rectangular tube shape that can be hermetically sealed.

As shown in FIG. 1A, when no load is applied from the outside, the upper surface 3f of the dielectric window 3 is formed in a curved surface that protrudes upward, and the lower surface 3b is formed flat. In FIG. 1B, a prior art dielectric window 30 is shown in broken lines. Thus, like the dielectric window 30 of the prior art, the dielectric window 3 has an axisymmetric shape with the center portion being the most convex.

FIG. 2 is a cross-sectional view of the dielectric plate 31 before the curved surface is formed in the dielectric window 3 shown in FIG. 1A.
Hereinafter, a method for forming the curved surface of the dielectric window 3 in the method for manufacturing the dielectric window 3 will be described.

First, a dielectric plate 31 made of a dielectric material having a pair of upper and lower surfaces that are substantially flat and have a predetermined thickness is prepared.
As shown in FIG. 2, the dielectric plate 31 may have a size required for the dielectric window 3 of the plasma processing apparatus 1. The dielectric plate 31 has substantially the same shape and the same size as the dielectric window 30 of the prior art, and an extra surface layer portion having a thickness of at least 0.1 mm is provided on the upper surface 3f side as a polishing margin. It is a thing. The dielectric plate 31 is not particularly limited, and can be formed by, for example, a method of forming a dielectric material by compression molding or a method of cutting and separating a cylindrical dielectric material into a thin plate material.

3A and 3B are schematic cross-sectional views illustrating a method for manufacturing the dielectric window 3 according to the embodiment of the present invention. The method for manufacturing the dielectric window 3 corresponds to the method for manufacturing the dielectric window according to the first aspect of the present invention.

As shown in FIGS. 3A and 3B, in the present embodiment, a jig 20 imitating the chamber 2 of the plasma processing apparatus 1 is used to form a curved surface in the dielectric window 3. The jig 20 includes a jig body 21, an O-ring 22, and a vacuum pump 23 as a vacuum decompression unit. The jig main body 21 is a bottomed rectangular tube-shaped casing having a rectangular opening at the top, and when the upper opening is sealed with the dielectric window 3, the inside of the jig main body 21 is sealed and the inside is in a vacuum state. It has become possible. The O-ring 22 has substantially the same shape and the same size as the upper opening of the jig main body 21 and is disposed on a rectangular support frame along the upper opening of the jig main body 21. The structure of the jig body 21 is the same as that of the chamber 2 that supports the dielectric window 3 with a rectangular support frame.

Next, as shown in FIG. 3A, the dielectric plate 31 is installed on a rectangular support frame along the upper opening of the jig body 21 so that the O-ring 22 is interposed (installation step).
At this time, the center of the O-ring 22 is set to coincide with the center of the dielectric plate 31. In this state, the inside of the jig body 21 is evacuated and decompressed using the vacuum pump 23. Thereby, the inside of the jig body 21 can be depressurized to the same pressure as the plasma generation conditions of the actual plasma processing apparatus 1.

Next, the inside of the jig main body 21 (the jig 20) is evacuated and decompressed by the vacuum pump 23, so that the actual plasma processing apparatus 1 is brought into a vacuum state where plasma can be generated. Then, a pressure difference is generated with the dielectric window 3 as a boundary. Then, as shown in FIG. 3A, the region surrounded by the O-ring 22 on the lower surface of the dielectric plate 31 is convex toward the inside (downward) of the jig body 21 due to the pressure difference between the inside and outside of the jig 20. Gradually bend (differential pressure step).

Then, when the pressure inside the jig main body 21 is the same as the plasma generation conditions in the actual plasma processing apparatus 1, for example, about 10 [mPa] to several tens [Pa], the pressure reduction operation by the vacuum pump 23 is performed. And the state where the lower surface of the dielectric plate 31 is deformed downward and convex is maintained.

Next, as shown in FIG. 3B, the upper surface (one surface) located on the outer side of the jig body 21 of the dielectric plate 31 is flat and uniform using a polishing jig so that the height is uniform. Polishing (one-side flattening step).

Here, the central portion of the upper surface of the dielectric plate 31 is hardly polished, and the amount of polishing increases in the peripheral region on the upper surface of the dielectric plate 31. At this time, the degree of bending of the lower surface of the dielectric plate 31 located inside the jig body 21 is prevented from changing.

As described above, when the polishing of the upper surface of the dielectric plate 31 is completed, the dielectric window 3 is created from the dielectric plate 31. Next, the inside of the jig body 21 is released to atmospheric pressure, and the dielectric window 3 is removed from the jig 20. The dielectric window 3 released from the pressure difference between the inside and outside of the jig 20 is free from bending. Then, the lower surface 3b of the dielectric window 3 returns to flat as shown in FIG. 1A. On the other hand, as shown in FIG. 1B, the upper surface 3f of the dielectric window 3 has a curved surface that is convex upward and has the highest central portion. This is because in the state where the entire dielectric window 3 is bent downward, the central portion is hardly shaved and the peripheral region is polished.

According to the method for manufacturing the dielectric window 3 of the present embodiment, the dielectric plate 31 is hardly polished at the center of the upper surface located outside the chamber 2 of the plasma processing apparatus 1 and is polished toward the outer peripheral region. The amount was increasing. For this reason, the upper surface 3f of the dielectric window 3 is convex upward and has a smooth curved surface. When the dielectric window 3 is actually used in the plasma processing apparatus 1, the dielectric window 3 is bent because the inside of the chamber 2 is in a vacuum state. According to the manufacturing method of the dielectric window 3 of the present embodiment, the upper surface 3f positioned outside the chamber 2 is polished flatly in a state where the deflection is generated by the pressure difference between the inside and outside of the jig body 21 imitating the chamber 2. is doing. For this reason, as shown in FIG. 1A, the upper surface 3f of the dielectric window 3 has a curved surface that protrudes upward when there is no difference in the pressure applied to the upper surface 3f and the lower surface 3b. However, the upper surface 3f becomes flat when actually used in the plasma processing apparatus 1, as shown in FIG. 3B.

As shown in FIG. 1A, the dielectric window 3 of the present embodiment has an axially symmetric shape. Therefore, when the dielectric window 3 is installed in the plasma processing apparatus 1 and performs plasma processing, the dielectric window 3 is positioned outside the chamber 2 of the dielectric window 3. The upper surface 3f (one surface) can be deformed stably and flatly.

FIG. 4 is an overall cross-sectional view of the plasma processing apparatus 1 according to the embodiment of the present invention. This plasma processing apparatus 1 corresponds to the plasma processing apparatus according to the third aspect of the present invention.
As shown in FIG. 4, a plasma processing apparatus 1 according to an embodiment of the present invention includes a bottomed square cylindrical chamber 2, a dielectric window (top plate) 3, a disk-shaped antenna 4, a waveguide 5, a micro A wave source 6, a cooling jacket 7 as a cooling means, a substrate holding table 8, a vacuum pump 9, a high frequency power supply 10, a gas passage 11, a temperature sensor 12, and a support member 13 are provided. The chamber 2 has a sealable structure in order to generate plasma therein. The antenna 4 includes a slot plate 4a made of metal (shield member), and a slow wave plate 4b arranged adjacent to and above the slot plate 4a and made of a dielectric. The waveguide 5 is a so-called coaxial waveguide, and includes an inner conductor 5b and a cylindrical outer conductor 5a disposed so as to form a cylindrical gap through which microwaves pass on the outer periphery of the inner conductor 5b. It is equipped with.

The support member 13 is substantially the same shape and the same size as the upper opening of the chamber 2 (peripheral edge of the dielectric window 3), and is disposed on a rectangular support frame along the upper opening of the chamber 2. A dielectric window 3 is disposed on the rectangular support frame via a support member 13.

FIG. 5 is a plan view showing an example of the slot plate 4a according to the embodiment of the present invention.
As shown in FIG. 5, the slot plate 4a is disposed adjacent to the lower side of the slow wave plate 4b, and a large number of

slots

41 and 42 are formed therethrough. Thus, the slot plate 4a is located below the slow wave plate 4b. For this reason, the microwave propagates so as to spread in the surface direction of the slow wave plate 4b with the position introduced from the waveguide 5 as the center.

More specifically, as shown in FIG. 5, the

slots

41 and 42 are formed on the concentric circles of a plurality of concentric circles at substantially equal angular intervals. Each

slot

41, 42 is formed to be orthogonal to each other. Then, the microwave propagates in the radial direction of the slot plate 4 a centering on the position introduced from the waveguide 5, and is radiated downward through the

slots

41 and 42. The microwaves are repeatedly reflected inside the top plate 3 and interfere to strengthen each other to form a standing wave. In the region immediately below the top plate 3, plasma is formed in a direction perpendicular to the length direction of the

slots

41 and 42.

Returning to FIG. 4, the upper opening of the chamber 2 of the plasma processing apparatus 1 is closed by the dielectric window 3. The upper surface 3 f of the dielectric window 3 forms a convex curved surface toward the outside (upward) of the chamber 2. In addition, the antenna 4 is arranged above the dielectric window 3 (on one side) so as to overlap.

A waveguide 5 is connected to the center of the antenna 4. Specifically, the lower end portion of the inner conductor 5b is in contact with the slot plate 4a. The slow wave plate 4b is located between the cooling jacket 7 and the slot plate 4a, and compresses the wavelength of the microwave introduced from the waveguide 5 and shifts it to the short wavelength side. The slow wave plate 4b can be formed of a dielectric material such as SiO ₂ or Al ₂ O ₃ .

In the present embodiment, as shown in FIG. 4, the cooling jacket 7 is provided so as to be in contact with and overlap the upper surface (one surface) of the antenna 4. By causing a heat medium to flow through the cooling flow path 7a of the cooling jacket 7, even if heat generated when plasma is generated inside the chamber 2 is accumulated in the dielectric window 3 and the antenna 4 and becomes high temperature, The heat can be taken away and the dielectric window 3 and the antenna 4 can be cooled.

In the present embodiment, as shown in FIG. 4, the temperature sensor 12 is provided on the antenna 4 that is made of metal and is likely to reach the highest temperature. The temperature measurement result by the temperature sensor 12 is fed back to a control device (not shown) that controls the plasma processing apparatus 1. And the temperature of a heat medium is controlled by the control apparatus, adjusting the quantity of the heat medium sent through the cooling flow path 7a. Thereby, the temperature of the top plate 3 is more reliably maintained constant.

In order to perform plasma processing on the substrate W to be processed by the plasma processing apparatus 1 of the present embodiment, the upper opening of the chamber 2 of the plasma processing apparatus 1 is closed by the dielectric window 3 as shown in FIG. Seal the inside. Next, the inside of the chamber 2 is evacuated and depressurized to a vacuum state in which plasma is generated. Then, a pressure difference is generated with the dielectric window 3 as a boundary. Then, due to the pressure difference between the inside and outside of the chamber 2, the lower surface 3 b of the dielectric window 3 is gradually bent so as to become a convex curved surface toward the inside (downward) of the chamber 2. For example, when the plasma processing apparatus 1 is an apparatus for processing a 300 mm silicon wafer, the diameter of the dielectric window 3 is about 400 mm, and the maximum amount of deflection at the convex portion of the lower surface 3b is about 0.1 mm.

In the state shown in FIG. 4, when the inside of the chamber 2 is evacuated and depressurized using the vacuum pump 9, the dielectric window 3 that closes the upper opening of the chamber 2 is brought into the chamber 2 due to the pressure difference inside and outside the chamber 2. Receive the load to head. For example, if the inside of the chamber 2 is set to a pressure under plasma generation conditions in which plasma is generated in a good state, for example, about 10 [mPa] to several tens [Pa], the outside of the chamber 2 is atmospheric pressure. A pressure difference of about 10 ⁵ [Pa] occurs between the inside and the outside of 2. As shown in FIG. 4, the peripheral edge portion of the dielectric window 3 is supported by a support member 13 disposed on a rectangular support frame along the upper opening of the chamber 2.

For this reason, the upper surface 3f of the dielectric window 3 of the present embodiment is flat during the plasma processing. That is, the region surrounded by the support member 13 on the lower surface 3 b of the dielectric window 3 is gradually bent so as to protrude toward the inside (downward) of the chamber 2 due to the pressure difference between the inside and outside of the chamber 2. That is, the flat lower surface 3b is deformed into a convex curved surface toward the inside of the chamber 2, and the upper convex surface 3f is flat.

Hereinafter, plasma processing of a semiconductor substrate (substrate W to be processed) using the plasma processing apparatus 1 of the present embodiment will be described.
In the state shown in FIG. 4, the inside of the chamber 2 is evacuated and decompressed by using the vacuum pump 9 to be in a vacuum state. Next, a microwave is supplied from the microwave source 6 to the antenna 4 through the waveguide 5. Then, the microwave is radiated downward through the

slots

41 and 42 of the slot plate 4 a while propagating between the slot plate 4 a and the slow wave plate 4 b in the radial direction of the antenna 4 and reaches the dielectric window 3. . At this time, the microwave travels while rotating the polarization plane inside the dielectric window 3 to form a circularly polarized wave. The microwave passes through the dielectric window 3 and is radiated into the chamber 2.

The microwave radiated into the chamber 2 through the waveguide 5 and the dielectric window 3 is repeatedly reflected while maintaining the wavelength at a predetermined length with the position introduced from the waveguide 5 as the center. However, it propagates through the dielectric window 3. Since the microwave forms a coarse / dense position pattern in the dielectric window 3, the plasma density distribution in the chamber 2 is formed and stabilized.

Then, when a plasma excitation gas such as argon (Ar) or xenon (Xe) is supplied into the chamber 2, the gas is ionized in the chamber 2 by the above-described microwave energy, and plasma is generated. Here, for example, plasma processing such as so-called plasma CVD (Plasma Chemical Vapor Deposition) can be performed. That is, a thin film forming gas is supplied into the chamber 2 by a lower gas supply means (not shown). Then, by activating the gas, a thin film such as Si is deposited on the substrate W to be processed which is a semiconductor substrate placed on the substrate holder 8. In this way, by repeating a series of processes of loading the substrate to be processed W into the chamber 2, depositing a thin film, and then unloading after the plasma processing, plasma processing is continuously performed on a predetermined number of substrates to be processed W. It can be performed.

In the plasma processing apparatus 1 of the present embodiment, the dielectric window 3 and the antenna 4 are cooled by the cooling jacket 7 as described above. However, due to the heat generated when plasma is generated inside the chamber 2, the dielectric window 3 and the antenna 4 are more or less expanded and deformed according to their respective thermal expansion coefficients.

On the other hand, according to the plasma processing apparatus 1 of the present embodiment, as described above, the upper surface 3f of the dielectric window 3 is flat during the plasma processing. An antenna 4 is disposed so as to overlap the upper surface 3 f of the dielectric window 3 located outside the chamber 2. For this reason, during the plasma processing, the slot plate 4a of the antenna 4 expands while maintaining the adhesion with the dielectric window 3 even if it is deformed by thermal expansion. For this reason, a gap does not occur between the dielectric window 3 and the antenna 4, and the occurrence of abnormal discharge is prevented. As a result, the plasma density distribution in the chamber 2 can be stabilized.

Further, according to the plasma processing apparatus 1 of the present embodiment, the slot plate 4a is maintained in a planar state while being in close contact with the dielectric window 3. Further, the cooling jacket 7 and the slow wave plate 4b are in close contact with each other before the plasma is generated inside the chamber 2, that is, before the inside of the chamber 2 is evacuated and decompressed. Therefore, the antenna 4 (slot plate 4a and slow wave plate 4b) disposed between the dielectric window 3 and the cooling jacket 7 is not only between the dielectric window 3 but also the cooling jacket 7 at the time of thermal expansion. Adhesion can be maintained even between the two. For this reason, a gap does not occur between the antenna 4 and the dielectric window 3 and between the antenna 4 and the cooling jacket 7, and the occurrence of abnormal discharge during propagation of microwaves in the antenna is prevented. As a result, the plasma density distribution in the chamber 2 can be stabilized.

Further, according to the plasma processing apparatus 1 of the present embodiment, the dielectric window 3 and the antenna 4 and the antenna 4 and the cooling jacket 7 are in close contact with each other without generating a gap. For this reason, the heat accumulated in the dielectric window 3 and the antenna 4 can be dissipated out of the chamber 2 via the cooling jacket 7 and can be efficiently cooled. As a result, deformation of the dielectric window 3 and the antenna 4 due to heat is suppressed, no gap is generated between the antenna 4 and the dielectric window 3, and the occurrence of abnormal discharge during propagation of microwaves in the antenna is prevented. As a result, the plasma density distribution in the chamber 2 can be stabilized.

According to the method for manufacturing the dielectric window 3 according to the present embodiment, the dielectric window 3 is created so that the upper surface 3f of the dielectric window 3 returns to a plane during the plasma processing in the actual plasma processing apparatus 1. . For this reason, the dielectric window 3 of the present embodiment has a convex curved surface simply by polishing the lower surface thereof, and the dielectric window 3 is deformed in comparison with the dielectric window 3 in which the upper surface is deformed flat by the pressure difference between the inside and outside of the chamber 2. The upper surface 3f on the antenna 4 side of the body window 3 is in a state of excellent smoothness. Therefore, even if the antenna 4 is deformed due to thermal expansion, no gap is generated between the antenna 4 and the dielectric window 3, and the occurrence of abnormal discharge during propagation of microwaves in the antenna is prevented. As a result, the plasma density distribution in the chamber 2 can be stabilized.

In addition, according to the method for manufacturing the dielectric window 3 according to the present embodiment, the upper surface of the dielectric window 3 can be polished more flat than the case where the lower surface of the dielectric window 3 is simply polished to form a convex curved surface. It is not necessary to design a complicated curved surface shape. Therefore, according to the method for manufacturing the dielectric window 3 according to the present embodiment, the processing becomes easy and the manufacturing cost can be reduced.

According to the dielectric window 3 of the present embodiment, the adhesion between the antenna 4 and the dielectric window 3 is improved, so that not only abnormal discharge between the two members is prevented, but also the antenna 4 and the dielectric by the cooling jacket 7. The cooling efficiency of the body window 3 can be maintained high. The temperature change of the antenna 4 or the like that has a great influence on the plasma generation state can be made as small as possible to stabilize the electromagnetic field distribution in the dielectric window 3, that is, the plasma density distribution.

FIG. 6 is a partially enlarged view of FIG. 4 and shows the positional relationship between the dielectric window 3 and the antenna 4.
In the present embodiment, as shown in FIG. 6, a connector provided in the chamber 2 is provided above the dielectric window 3 as a support member that supports the peripheral portion of the slot plate 4 a of the antenna 4 without being fixed. 14 may be provided. When thermal expansion occurs, the slot plate 4a expands and deforms not only in the vertical direction in which the dielectric window 3 and the slow wave plate 4b exist, but also in the surface direction thereof. Therefore, when the peripheral portion of the slot plate 4a is fixed, the expansion in the surface direction is not absorbed and appears as a vertical distortion. However, the connector 14 supports the slot plate 4a in a state where it can be freely expanded and deformed in the surface direction. For this reason, even if expansion in the surface direction occurs in the slot plate 4a, the adhesion between the slot plate 4a and the dielectric window 3 is not affected. Therefore, the slot plate 4a of the antenna 4 expands while maintaining the adhesion with the dielectric window 3 during the plasma processing. For this reason, a gap does not occur between the slot plate 4a and the dielectric window 3, and the occurrence of abnormal discharge is prevented when the microwave propagates in the antenna. As a result, the plasma density distribution in the chamber 2 can be stabilized.

In the present embodiment, the plasma processing apparatus 1 performs plasma processing on a 300 mm silicon wafer, but it can also perform plasma processing on a silicon wafer having a larger diameter than 300 mm. As the diameter of the silicon wafer, which is the substrate to be processed W, increases, the plasma processing apparatus 1 becomes larger and the amount of deflection of the dielectric window 3 increases. Therefore, according to the technical idea of the present invention, a greater effect can be obtained. Be able to.

In the present embodiment, the contact resistance during heat conduction with the antenna 4 can be reduced by polishing the surface of the dielectric window 3 so that the surface roughness thereof is reduced. Therefore, the cooling efficiency of the dielectric window 3 by the cooling jacket 7 can be maintained high. For this reason, according to the present embodiment, the dielectric window 3 is not easily affected by temperature changes, and plasma can be stably generated in the chamber 2 without affecting the plasma generation conditions.

Further, in the method of manufacturing the dielectric window 3 described in the present embodiment, the method of manufacturing the dielectric plate 31 and the structure of the jig 20 imitating the plasma processing apparatus 1 are examples, and the present invention is not limited to these. Furthermore, the structure of the plasma processing apparatus 1 and the substrate W to be processed can be changed in various ways within the scope of the technical idea of the present invention, and are not limited to the above-described embodiments.

This application is based on Japanese Patent Application No. 2008-205888 filed on August 8, 2008, and includes a detailed description of the invention (specification), claims, drawings, and Includes an overview. The contents disclosed in Japanese Patent Application No. 2008-205888 are all incorporated herein by reference.

1 Plasma processing equipment (microwave plasma processing equipment)
2 chamber (plasma processing vessel)
3 Dielectric window (top plate)
4 Antenna 4a Slot plate 4b Slow wave plate 5 Waveguide 7 Cooling jacket 9, 23 Vacuum pump 13 Support member 20 Jig 22 O-ring 31 Dielectric plate

Claims

It is used in a plasma processing apparatus for generating plasma in a plasma processing container using microwaves and performing plasma processing on an object to be processed, and the inside of the plasma processing container can be sealed in a vacuum state capable of generating plasma. A method of manufacturing a dielectric window that propagates the microwave and transmits the microwave into the plasma processing container,
An installation step of installing a dielectric plate in a jig that can be in a vacuum state inside;
By evacuating and depressurizing the inside of the jig by a vacuum depressurizing means, a vacuum state similar to that of the plasma processing vessel is generated, a pressure difference is generated with the dielectric plate as a boundary, and the dielectric plate is placed inside the jig. A differential pressure step that deforms to become convex toward the surface,
A single-side flattening step of flattening one side of the dielectric plate located outside the jig, while maintaining a pressure difference with the dielectric plate as a boundary;
A method of manufacturing a dielectric window, comprising:
A dielectric window obtained by the method of manufacturing a dielectric window according to claim 1,
When the dielectric window is installed in the plasma processing apparatus, when there is no pressure difference between the inside and outside of the dielectric window, one surface located outside the plasma processing container is a curved surface convex outward. ,
The dielectric window is bent so as to be convex toward the inside of the plasma processing container when the inside of the plasma processing container is in a vacuum state in which plasma can be generated, and is positioned outside the plasma processing container. A dielectric window characterized in that one side to be flattened.
3. The dielectric window according to claim 2, wherein the dielectric window has an axisymmetric shape with a convex portion at the center.
A plasma processing apparatus for generating plasma in a plasma processing container using a microwave and performing plasma processing on an object to be processed,
A microwave source for generating the microwave;
A waveguide for transmitting the microwave;
An antenna that radiates the microwave transmitted from the microwave source through the waveguide;
A dielectric window that propagates the microwave radiated from the antenna and transmits the microwave into the plasma processing container,
A plasma processing apparatus comprising the dielectric window according to claim 1 as the dielectric window.
5. The plasma processing apparatus according to claim 4, wherein the antenna is arranged so as to overlap one surface side of the dielectric window located outside the plasma processing container.
The antenna includes a slot plate and a slow wave plate disposed adjacent to the slot plate, and the slot plate is supported by a support member so as to be deformable in a plane direction. The plasma processing apparatus according to claim 4.
The antenna includes a slot plate and a slow wave plate disposed adjacent to the slot plate, wherein the plurality of pairs of slots are spaced substantially equiangularly on each concentric circle of the concentric circles. The plasma processing apparatus according to claim 4, wherein the pair of slots are formed so as to be orthogonal to each other.
The plasma processing apparatus according to claim 4, wherein a cooling means for cooling the antenna is provided so as to contact and overlap one surface of the antenna.
The plasma processing apparatus according to claim 6, wherein the slot plate is made of metal, and the slow wave plate is made of a dielectric material.