JP2005141941A - Surface wave excited plasma treatment apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a surface wave excited plasma treatment apparatus capable of generating homogeneous plasma over the whole area of a dielectric board, capable of uniformly applying plasma treatment on a substrate to be treated having a large area. <P>SOLUTION: The surface wave exciting plasma treatment device is provided with a microwave-generating part 1 generating microwave M; a center waveguide tube 10 for introducing the microwave M from the microwave generating part 1 and transmitting it; a slot wave-guide tube 20 having a slot antenna, introducing the microwave M from the center waveguide tube 10 and transmitting it; and a dielectric board 4 for introducing the microwave M through the slot antenna and transmitting it as the surface wave, generating the plasma in a plasma treatment chamber 2. The center wave-guide tube 10 is connected to the slot wave-guide tube 20 at the center of both end parts E1, E2 of the slot wave-guide tube 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a surface wave excited plasma processing apparatus that performs CVD, etching, and the like using surface wave excited plasma.

  In a semiconductor manufacturing process, a plasma processing apparatus that uses plasma to perform CVD film formation, etching, or the like is used. As such a plasma processing apparatus, a parallel plate type plasma processing apparatus, an electron cyclotron resonance (ECR) plasma processing apparatus, and the like have been used. Furthermore, in recent years, a surface wave plasma (SWP) plasma processing apparatus that can easily generate a plasma having a larger area has been used (for example, see Patent Document 1).

  In the SWP plasma processing apparatus, microwave power is introduced into a plasma generation chamber from a slot antenna provided in a microwave waveguide through a dielectric plate, and a process in the plasma generation chamber is caused by surface waves generated on the surface of the dielectric plate. A gas is excited to generate surface wave excitation plasma. Since the surface wave spreads the boundary between the dielectric plate and the plasma in the surface direction of the dielectric plate, a plasma having a large area can be obtained (see, for example, Patent Document 1).

Japanese Patent Laid-Open No. 10-22098 (second page, FIG. 10)

  In the dielectric plate in the extending direction of the waveguide, the electron density decreases as the distance from the microwave introduction port of the waveguide decreases. When the length of the dielectric plate is about 35 cm or more, the dielectric plate extends in the length direction. There is a phenomenon that the plasma is difficult to spread. In particular, when nitrogen gas, oxygen gas or other active gas species are used as the process gas, the tendency is remarkable. For this reason, it has been difficult to obtain a uniform plasma spreading over the entire surface of the dielectric plate.

  (1) The surface wave excitation plasma processing apparatus according to claim 1 includes a microwave generation unit that generates a microwave, a central waveguide that introduces and propagates the microwave from the microwave generation unit, and a slot antenna. The center waveguide includes a slot waveguide that introduces and propagates microwaves from the central waveguide, and a dielectric member that introduces microwaves through the slot antenna and propagates as surface waves to generate plasma in the plasma processing chamber. The tube is characterized in that it is connected to the slot waveguide in the middle between both end portions of the slot waveguide.

  (2) In the surface wave excitation plasma processing apparatus of claim 1, the distance from the connection position of the central waveguide and the slot waveguide to the terminal end of the slot waveguide is an integral multiple of the in-tube wavelength λg of the microwave It is preferable to set to. Furthermore, the distance from the connection position to the slot antenna adjacent to the connection position is preferably set to (n / 2) λg, where n is a positive integer.

  (3) A surface wave excitation plasma processing apparatus according to a fourth aspect introduces a microwave from a microwave generator that generates a microwave, a plurality of slot waveguides having a slot antenna, and a microwave generator. A branching waveguide for branching a wave and sending it to each of the plurality of slot waveguides, and a dielectric member for introducing a microwave through the slot antenna and propagating it as a surface wave to generate plasma in the plasma processing chamber The branching waveguide is characterized in that a plurality of slot waveguides are connected in parallel at the center between both end portions of each of the plurality of slot waveguides.

(4) In the surface wave-excited plasma processing apparatus according to claim 4, the distance from the branching position of the branching waveguide to each terminal part of the plurality of slot waveguides is set to an integral multiple of the in-tube wavelength λg of the microwave. It is preferable to do. Further, the distance from the branch position to the slot antennas close to the branch positions of the plurality of slot waveguides is preferably set to (n / 2) λg, where n is a positive integer.
(5) In the surface wave excitation plasma processing apparatus, a termination matching unit can be provided at each termination portion of the slot waveguide.

  According to the present invention, uniform plasma can be generated over the entire region of the dielectric member, and a large substrate to be processed can be uniformly subjected to plasma processing.

Hereinafter, a surface wave excitation plasma processing apparatus (hereinafter referred to as SWP processing apparatus) according to the present invention will be described with reference to FIGS.
<First Embodiment>
FIG. 1 is an overall configuration diagram showing a schematic configuration of the SWP processing apparatus according to the first embodiment of the present invention. FIG. 2A is a longitudinal sectional view of the plasma generation unit of the SWP processing apparatus according to the first embodiment, and FIG. 2B is a bottom view thereof. In FIGS. 1 and 2, the direction is represented by orthogonal coordinates.

The SWP processing apparatus of the present embodiment includes a microwave generation unit 1, an apparatus main body 2, and a plasma generation unit 100 provided on the upper surface of the apparatus main body 2. The microwave generator 1 generates a microwave M of 2.45 GHz and sends it to the plasma generator 100. The apparatus main body 2 is a hermetically sealed container for performing plasma processing of the substrate S to be processed, such as process gas such as N ₂ gas and Ar gas, SiH ₄ gas, Si ₂ H ₆ gas, H ₂ gas, and O ₂ gas. The material gas is introduced to maintain the inside of the container at a predetermined pressure. The upper surface of the apparatus body 2 is configured to be kept airtight by the upper plate 3 and the dielectric plate 4.

  The plasma generation unit 100 includes a central waveguide 10, a slot waveguide 20, and a dielectric plate 4. The central waveguide 10 is a tube having a rectangular cross section extending in the Z direction, one end of which is connected to the microwave generator 1 and the other end is substantially the center of the slot waveguide 20. It is connected to the. The slot waveguide 20 is a tube having a rectangular cross section extending in the X direction, and both ends E1 and E2 are closed. Both ends E1, E2 can be moved along the X direction by the end matching devices 20b, 20c (see FIG. 2). The central waveguide 10 and the slot waveguide 20 are made of an aluminum alloy.

  The dielectric plate 4 is a flat plate disposed in contact with the lower surface of the slot waveguide 20 and is made of quartz, alumina, or the like. As will be described later, microwave power is introduced from the slot waveguide 20 into the dielectric plate 4 to generate plasma in the internal space of the apparatus body 2.

  Referring to FIG. 2, slot antennas 21 to 28 are provided on the bottom plate 20 a of the slot waveguide 20. The inner surface of the bottom plate 20a is a surface called a magnetic field surface (H surface). The slot antennas 21 to 28 are long rectangular openings formed at predetermined intervals along the extending direction (X direction) of the slot waveguide 20.

  The connection center C1 is an intersection of the center line CL1 of the central waveguide 10 and the center line SL1 of the slot waveguide 20, and is a point representing the connection position between them. The microwave M propagates in the central waveguide 10 in the −Z direction and is separated into two at the connection center C1, and one propagates in the slot waveguide 20 in the + X direction to the end E1. It propagates in the slot waveguide 20 in the −X direction to the end E2. A part of the microwave M is reflected at both ends E1 and E2.

  The microwave M propagating in the slot waveguide 20 radiates to the dielectric plate 4 through the slot antennas 21 to 28 and is introduced into the apparatus main body 2 through the dielectric plate 4. The microwave M becomes a surface wave, propagates along the surface of the dielectric plate 4, and spreads over the entire area of the dielectric plate 4. The gas in the apparatus main body 2 is ionized and dissociated by the energy of the surface wave, and plasma is generated in a region corresponding to the area of the dielectric plate 4. Processing such as film formation, etching, and ashing is performed using this plasma.

Hereinafter, the dimensions of the central waveguide 10 and the slot waveguide 20 and the positional relationship between the slot antennas 21 to 28 will be described.
The wavelength of the microwave M propagating in the waveguide is λg, the distance between the connection center C1 and the terminal E1 and the distance between the connection center C1 and the terminal E2 are L1, and L1 is set to an integral multiple of λg. That is, if n is a positive integer, it can be expressed as L1 = nλg. A standing wave of the microwave M is formed in the slot waveguide 20, and the microwave M having the same phase can always be strongly emitted from a certain position of the slot waveguide 20 by forming the standing wave.

With reference to FIG. 3, the operation and effect of the SWP processing apparatus and the plasma generation unit configured as described above will be described.
FIG. 3A is a perspective view schematically showing a plasma generation unit 100 including the central waveguide 10 and the slot waveguide 20 of the present embodiment, and FIG. 3B uses the plasma generation unit 100. It is a graph which shows the electron density distribution of the plasma at the time qualitatively. FIG. 4 is a diagram given as a comparative example, FIG. 4 (a) is a perspective view schematically showing a conventional plasma generation unit 100A, and FIG. 4 (b) is a plasma generated when the plasma generation unit 100A is used. It is a graph which shows an electron density distribution qualitatively. The plasma generators 100 and 100A have the same dimensions except for the connection position of the central waveguide and the slot waveguide.

  In the graphs of FIG. 3B and FIG. 4B, the horizontal axis represents the position in the X direction. In FIG. 3B, the electron density of plasma in the X direction is the highest at the connection center C1, and does not decrease so much even in the vicinity of the terminations E1, E2. On the other hand, in FIG. 4B, the electron density of the plasma in the X direction is highest at the introduction end of the microwave M, but is greatly reduced at the end. That is, when using the plasma generation unit 100 of the present embodiment, the electron density distribution is flatter than when using the plasma generation unit 100A of the comparative example. Therefore, when the plasma generation unit 100 is used, uniform plasma is generated over the entire area of the dielectric plate, and a large substrate to be processed can be uniformly plasma processed.

With reference to FIG. 2 again, the positional relationship between the slot antennas 21 to 28 will be described.
Among the slot antennas 21 to 28, the slot antennas 21 and 25 are close to the connection center C1. The distance between the connection center C1 and the slot antenna 21 and the distance between the connection center C1 and the slot antenna 25 are both set to λg / 2. Further, the arrangement interval between the slot antennas is set to λg. The distance between the connection center C1 and the slot antenna 21 and the distance between the connection center C1 and the slot antenna 25 need only satisfy the condition of (n / 2) λg, where n is a positive integer.

  Thus, by arranging the slot antennas 21 to 28, the peak position of the electric field strength of the standing wave of the microwave M coincides with the position of the slot antennas 21 to 28, and the microwave M is effectively radiated. Is called. Further, the phase of the standing wave is slightly shifted as the microwave M propagates. However, by making both ends E1 and E2 of the slot waveguide 20 variable, the position shift can be corrected.

  This state will be generally described with reference to FIG. FIG. 5 is a graph showing the electric field strength distribution of the standing wave of the microwave M in the waveguide, and A1 and A2 indicate the microwave introduction positions of the waveguide. FIG. 5A shows a case where the microwave introduction position A1 is not considered at all. There is a shift of s1 between the position of the first slot antenna a1 and the peak position of the standing wave, and a shift is also generated in the other slot antennas a2 to a5.

  FIG. 5B shows a case where the microwave introduction position is adjusted to A2 so that the positional deviation s1 becomes zero. This adjustment is to set the distance between the microwave introduction position A2 and the position of the first slot antenna a1 to (n / 2) λg, where n is a positive integer. However, although the position of the first slot antenna a1 matches the peak position of the standing wave, the other slot antennas a2 to a5 are misaligned. When the positional deviations of the slot antennas a2 to a5 are s2, s3, s4, and s5 in this order, s2 <s3 <s4 <s5. That is, the position deviation increases as the distance from the microwave introduction position A2 increases.

  The connection center C1 in the present embodiment corresponds to the microwave introduction position A2, and as shown in FIG. 5B, by adjusting the phase of the standing wave and the position of the slot antenna, Radiation is performed effectively. Therefore, in the case of the slot waveguide having the same length, the positional deviation can be suppressed to be smaller when the microwave is introduced from the center than when the microwave is introduced from one side of the waveguide.

  FIG. 5C shows a case where the microwave introduction position remains the same as A2 in FIG. 5B, and the termination position is adjusted by the distance x by the termination matching unit b. The position of the first slot antenna a1 coincides with the peak position of the standing wave, and there is almost no deviation in other slot antennas. That is, if the end position is adjusted, the microwave M is more effectively emitted.

<Second Embodiment>
FIG. 6 is a perspective view showing a schematic configuration of the plasma generation unit of the SWP processing apparatus according to the second embodiment of the present invention. FIG. 7A is a longitudinal sectional view of the plasma generation unit of FIG. 6 cut along a plane P, and FIG. 7B is a bottom view of the plasma generation unit of FIG. 6 viewed from the Z direction. 6 and 7, directions are represented by orthogonal coordinates.

The SWP processing apparatus according to the present embodiment is greatly different from the SWP processing apparatus according to the first embodiment in the configuration of the plasma generation unit. Therefore, explanation is omitted.
Referring to FIG. 6, the plasma generation unit 200 includes a branching waveguide 11, slot waveguides 30 and 40, and a dielectric plate 4A. The branching waveguide 11 includes a microwave introduction port 11a and a branching part 11b that branches right and left. The branched waveguide 11 is a tube having a rectangular cross section, one end of which is connected to a microwave generator (not shown), and the other end branched into two is approximately at the center of the slot waveguides 30 and 40, respectively. It is connected. The slot waveguides 30 and 40 are tubes having a rectangular cross section extending in the X direction, and are arranged in parallel at predetermined intervals in the Y direction in contact with the upper surface of the dielectric plate 4A. In the present embodiment, the lengths of the slot waveguides 30 and 40 are both (L2 + L2).

  Referring to FIG. 7, the slot waveguide 30 is provided with slot antennas 31 to 38, and the slot waveguide 40 is provided with slot antennas 41 to 48. E3 to E6 are closed. The terminal matching units provided at the terminal ends E3 to E6 are not shown.

In FIG. 7, the branch point O is on the center line CL2 of the branch waveguide 11 and is a point representing the branch position. The center line CL <b> 2 is a center line along the microwave propagation path in the branching waveguide 11. The connection center C2 is an intersection of the center line CL2 of the branching waveguide 11 and the center line SL2 of the slot waveguide 30, and is a point representing the connection position between them. The distance from the branch point O to the connection center C2 is d1. As shown in FIG. 7A, the distance in the Z direction among the distances d1 is α.
Similarly, the connection center C3 is an intersection of the center line CL2 of the branching waveguide 11 and the center line SL3 of the slot waveguide 40, and is a point representing the connection position between them. The distance from the branch point O to the connection center C3 is d2.

  The microwave M enters from one end of the branching waveguide 11, is separated into two at the branch point O, and further separated into two at the connection centers C2 and C3. One separated at the connection center C2 propagates in the slot waveguide 30 in the + X direction to the end E3, and the other propagates in the slot waveguide 30 in the −X direction to the end E4. Similarly, one separated at the connection center C3 propagates in the slot waveguide 40 in the + X direction to the end E5, and the other propagates in the slot waveguide 40 in the −X direction to the end E6. The microwave M is radiated to the dielectric plate 4A through the slot antennas 31 to 38 and 41 to 48, and is introduced into the apparatus main body (not shown) through the dielectric plate 4A.

Hereinafter, the dimensions of the branch waveguide 11 and the slot waveguides 30 and 40 and the positional relationship between the slot antennas 31 to 38 and 41 to 48 will be described.
When the wavelength of the microwave M propagating in the waveguide is λg, the distance (d1 + L2) between the branch point O and the end E3 or E4 of the slot waveguide 30 and the end point E5 of the branch point O and the slot waveguide 40 Alternatively, the distance (d2 + L2) from E6 is set to an integral multiple of λg.

  That is, when n2 and n3 are positive integers, a standing wave of the microwave M is formed in the slot waveguides 30 and 40 by setting d1 + L2 = n2 × λg and d2 + L2 = n3 × λg. . By forming the standing wave, the microwave M can always be strongly emitted from the fixed positions of the slot waveguides 30 and 40. Note that (d1 + L2) and (d2 + L2) may or may not be equal as long as the condition of an integral multiple of λg is satisfied.

Next, the positional relationship between the slot antennas 31 to 38 and 41 to 48 will be described.
In the slot waveguide 30, slot antennas 31 and 35 are close to the branch point O. In the slot waveguide 40, the slot antennas 41 and 45 are close to the branch point O. The distance between the branch point O and the slot antenna 31 or 35 is set to (n / 2) λg where n is a positive integer. Further, the arrangement interval between the slot antennas is set to λg.

  In FIG. 7B, since the distance between the connection center C2 and the slot antenna 31 or 35 is λg / 2, the distance from the branch point O to the connection center C2 is {(n−1) / 2} λg. You only have to set it. Similarly, since the distance between the connection center C3 and the slot antenna 41 or 45 is λg / 2, the distance from the branch point O to the connection center C3 may be set to {(n−1) / 2} λg. . Note that the distance from the connection center C2 to the slot antenna 31 and the distance from the connection center C2 to the slot antenna 35 need not satisfy the condition of an integral multiple of λg / 2.

  Thus, by setting the distance from the branch point O to the end position of the slot waveguide 30 or 40 and the positions of the slot antennas 31 to 38 and 41 to 48, the microwave M is radiated effectively. . As a result, uniform plasma can be generated over the entire surface of the dielectric plate 4A. In the present embodiment, since the two slot waveguides 30 and 40 are connected in parallel, the plasma generation region having a uniform electron density can be expanded in the Y direction as compared with the first embodiment.

  If three or more slot waveguides are connected in parallel, the plasma generation region having a uniform electron density can be further expanded.

  FIG. 8A is a plan view showing a schematic configuration of a plasma generation unit which is a modification of the second embodiment, and FIG. 8B is a side view seen from the A direction in FIG. 8A. is there. The plasma generation unit 300 includes a branching waveguide 11, slot waveguides 30, 40, 50, 60 and a dielectric plate 4B. C2, C3, C4 and C5 are connection centers between the branching waveguide 11 and the slot waveguides 30, 40, 50 and 60, respectively. As shown in FIG. 8B, among the distance d1 from the branch point O to the connection center C2, the distance in the Z direction is α, and each distance from the branch point O to the connection centers C3, C4, and C5. Is also α. The arrangement configuration of the branch waveguide 11 and the slot waveguides 30 and 40 is the same as that in FIG. For simplicity, the slot waveguides 30, 40, 50, 60 are all the same length (L2 + L2).

  The distance from the branch point O to the end E3 or E4 of the slot waveguide 30 is (d1 + L2). Similarly, the distance from the branch point O to the end E5 or E6 of the slot waveguide 40 is (d2 + L2). The distance from the branch point O to the end E7 or E8 of the slot waveguide 50 is (d3 + L2). The distance from the branch point O to the end E9 or E10 of the slot waveguide 60 is (d4 + L2).

By setting the distances (d1 + L2), (d2 + L2), (d3 + L2), and (d4 + L2) to an integral multiple of the guide wavelength λg, the microwave M is effectively radiated to the dielectric plate 4B. Thus, by setting the distance from the branch point O to the end of each slot waveguide, the microwave M introduced from one place is propagated widely in the parallel direction (Y direction) of each slot waveguide. be able to. Although illustration is omitted, the position of the slot antenna is provided as in FIG. Further, the termination matching units 30b, 30c, 40b, 40c, 50b, 50c, 60b, and 60c may be provided to make the terminations E3 to E10 variable.
The present invention is not limited to the embodiments described above as long as the characteristics are not impaired.

It is a whole block diagram which shows schematic structure of the SWP processing apparatus which concerns on the 1st Embodiment of this invention. FIG. 2A is a longitudinal sectional view of the plasma generation unit of the SWP processing apparatus according to the first embodiment, and FIG. 2B is a bottom view thereof. FIG. 3A is a perspective view of the plasma generation unit 100 of the SWP processing apparatus according to the first embodiment, and FIG. 3B is a qualitative analysis of the electron density distribution of the plasma when the plasma generation unit 100 is used. FIG. 4A is a perspective view of a conventional plasma generation unit 100A, and FIG. 4B is a graph qualitatively showing the electron density distribution of plasma when the plasma generation unit 100A is used. As a comparative example, FIG. FIG. It is a graph which shows generally the electric field strength distribution of the standing wave of the microwave M in a waveguide. It is a perspective view which shows schematic structure of the plasma production part of the SWP processing apparatus which concerns on the 2nd Embodiment of this invention. FIG. 7A is a longitudinal sectional view of the plasma generation unit of FIG. 6 cut along a plane P, and FIG. 7B is a bottom view of the plasma generation unit of FIG. 6 viewed from the Z direction. It is the top view and side view which show schematic structure of the plasma production part which is a modification of 2nd Embodiment.

Explanation of symbols

1: Microwave generator 2: Device body 3: Upper plate 4, 4A, 4B: Dielectric plate 10: Central waveguide 11: Branched waveguide 20, 30, 40, 50, 60: Slot waveguide 100 , 200, 300: Plasma generation unit C1 to C5: Connection center E1 to E10: Termination M: Microwave O: Branch point

Claims (7)

A microwave generator for generating microwaves;
A central waveguide for introducing and propagating the microwave from the microwave generator; and
A slot waveguide having a slot antenna for introducing and propagating the microwave from the central waveguide;
A dielectric member that introduces the microwave through the slot antenna and propagates it as a surface wave, and generates plasma in the plasma processing chamber;
The surface wave-excited plasma processing apparatus, wherein the central waveguide is connected to the slot waveguide at the center between both end portions of the slot waveguide. In the surface wave excitation plasma processing apparatus according to claim 1,
A surface wave excitation plasma processing characterized in that a distance from a connection position between the central waveguide and the slot waveguide to an end portion of the slot waveguide is set to an integral multiple of a microwave guide wavelength λg apparatus. In the surface wave excitation plasma processing apparatus according to claim 2,
A surface wave excitation plasma processing apparatus, wherein a distance from the connection position to a slot antenna adjacent to the connection position is set to (n / 2) λg where n is a positive integer. A microwave generator for generating microwaves;
A plurality of slot waveguides having slot antennas;
A branching waveguide for introducing the microwave from the microwave generation unit, branching the microwave and sending it to each of the plurality of slot waveguides;
A dielectric member that introduces the microwave through the slot antenna and propagates it as a surface wave, and generates plasma in the plasma processing chamber;
The surface wave excitation plasma processing apparatus, wherein the branching waveguide connects the plurality of slot waveguides in parallel at the center between both end portions of each of the plurality of slot waveguides. In the surface wave excitation plasma processing apparatus according to claim 4,
A surface wave excitation plasma processing apparatus characterized in that distances from branch positions of the branch waveguides to terminal portions of the plurality of slot waveguides are set to integral multiples of the in-tube wavelength λg of the microwaves. In the surface wave excitation plasma processing apparatus according to claim 5,
A surface wave characterized in that the distance from the branch position to the slot antennas close to the branch positions of the plurality of slot waveguides is set to (n / 2) λg, where n is a positive integer. Excited plasma processing equipment. In the surface wave excitation plasma processing apparatus of Claims 1-6,
A surface wave excitation plasma processing apparatus, wherein a termination matching unit is provided at each termination part of the slot waveguide.

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