JP5568608B2 - Plasma processing equipment - Google Patents

Description

  An aspect of the present invention relates to a plasma processing apparatus that plasma-processes a substrate by converting a processing gas introduced into a processing container into plasma.

  Conventionally, plasma processing apparatuses are used in various fields. Patent Document 1 discloses a plasma etching apparatus using a parallel plate as a plasma source.

  In recent years, a plasma etching apparatus using a radial line slot antenna has been developed as one of plasma sources (see Patent Document 2). In a plasma etching apparatus using a radial line slot antenna, a slot antenna having a large number of slots is installed on a dielectric window of a processing container. Microwaves radiated from a number of slots of the slot antenna are introduced into the processing space of the processing container through a dielectric window made of a dielectric. The processing gas is turned into plasma by microwave energy.

JP 2008-47687 A JP 2010-118549 A

  However, the conventional plasma processing apparatus cannot change the characteristics of the plasma processing in various ways. The present invention has been made in view of such problems, and an object of the present invention is to provide a plasma processing apparatus capable of variously changing the characteristics of plasma processing.

In order to solve the above-described problem, the first plasma processing apparatus supplies microwave energy into the processing container via a dielectric window disposed on the upper part of the processing container, and the processing from a gas supply source. A plasma processing apparatus for converting a processing gas supplied into a container into plasma and plasma processing a substrate disposed at a lower portion of the processing container, wherein the processing gas supplied from the gas supply source is supplied from the dielectric window. At least first and second gas introduction portions that are introduced at different positions, and the first gas introduction portion is a central introduction portion having a central introduction port located at a central portion of the dielectric window. The second gas introduction part is a peripheral introduction part having a plurality of peripheral introduction ports arranged along the circumferential direction of the space above the substrate and positioned below the dielectric window, and the antenna is The dielectric And a slot plate provided on one surface of the dielectric window, and the other surface of the dielectric window has a flat surface surrounded by an annular first recess, and a center of gravity of the flat surface. A plurality of second recesses formed in the flat surface so as to surround, and when viewed from a direction perpendicular to the main surface of the slot plate, in each slot in the slot plate, The center of gravity of the second concave portion is positioned so as to overlap.

  In the second plasma processing apparatus, the gas supply source includes first and second gas sources, and the first gas introduction unit is provided on the plasma excitation region side directly below the dielectric window, The second gas introduction unit is provided on the side of the plasma diffusion region directly above the substrate, the plasma excitation region has an electron temperature higher than that of the plasma diffusion region, and the first and second gas introduction units include Gas supply is performed from the first gas source, and gas supply is performed from the second gas source to the first and / or second gas introduction unit to change the plasma processing characteristics of the substrate. The amount of gas supplied to the first and second gas inlets can be changed so as to make it happen.

In the above-described plasma processing apparatus, the first gas introduction part is a central introduction part having a central introduction port located at a central part of the dielectric window, and the second gas introduction part is located above the substrate. A peripheral introduction portion having a plurality of peripheral introduction ports arranged along the circumferential direction of the space and positioned below the dielectric window.

The third plasma processing apparatus performs control to repeat a gas supply step from the first gas introduction unit and a gas supply step from the second gas introduction unit at a predetermined cycle.

The fourth plasma processing apparatus is provided in a common gas line connected to a common gas source and the common gas line, and the common gas line is branched into first and second branch common gas lines. And a flow splitter capable of adjusting a flow rate ratio of the gas flowing through the second branch common gas line, and an additive gas line connecting the additive gas source and at least one of the first and second branch common gas lines. The gas supply source includes the common gas source and the additive gas source, and the first gas introduction unit is connected to the first branch common gas line and is located above the central portion of the substrate. A second central gas inlet connected to the second branch common gas line and arranged along a circumferential direction of the space above the substrate, and the dielectric From the body window Characterized in that it is a peripheral inlet portion having a plurality of peripheral inlet port located downward.
The fifth plasma processing apparatus is provided in a common gas line connected to a common gas source, the common gas line, the common gas line is branched into first and second branch common gas lines, and the first plasma processing apparatus And a flow splitter capable of adjusting the ratio of the flow rate of the gas flowing through the second branch common gas line, and the flow splitter connected to the first branch common gas line and positioned above the central portion of the substrate placed on a table The central introduction part having a central introduction port, and a plurality of the peripheral introductions connected to the second branch common gas line and arranged along the circumferential direction of the space above the substrate and positioned below the dielectric window The peripheral introduction section having a mouth, and an additive gas line connecting the additive gas source and at least one of the first and second branch common gas lines.

  According to the plasma processing apparatus of the present invention, the characteristics of the plasma processing can be variously changed.

It is a longitudinal cross-sectional view of the plasma processing apparatus in one Embodiment of this invention. It is a block diagram which shows the detailed structure of a gas supply source. It is the III-III sectional view taken on the line of FIG. It is a disassembled perspective view of the structure in the vicinity of the slot plate. It is a top view of a slot plate. It is a top view of a dielectric material window. It is a top view of the antenna which combined the slot plate and the dielectric material window. It is sectional drawing of a dielectric material window. It is a top view of another slot board. It is a top view of another dielectric material window. It is a graph which shows the relationship between position X (mm) and electron concentration Ne (/ cm < ³ >). It is a graph which shows the relationship between a position (mm) and etching rate ER (nm / min). It is a graph which shows the relationship between a position (mm) and etching rate ER (nm / min). It is the perspective view (a) and sectional drawing (b) of a slot and the recessed part vicinity. It is a figure which shows the positional relationship of a slot and a recessed part. It is a figure which shows the center introduction part improved.

  An embodiment of the present invention will be described below with reference to the accompanying drawings. In the present specification and drawings, substantially the same components are denoted by the same reference numerals.

  FIG. 1 is a longitudinal sectional view of a plasma processing apparatus in one embodiment of the present invention.

  The plasma processing apparatus 1 includes a cylindrical processing container 2. The ceiling of the processing container 2 is closed with a dielectric window (top plate) 16 made of a dielectric. The processing container 2 is made of, for example, aluminum and is electrically grounded. The inner wall surface of the processing container 2 is covered with an insulating protective film 2f such as alumina.

  A base 3 for placing a semiconductor wafer (hereinafter referred to as a wafer) W as a substrate is provided in the center of the bottom, which is the lower part of the processing container 2. A wafer W is held on the upper surface of the table 3. The table 3 is made of a ceramic material such as alumina or alumina nitride. A heater 5 is embedded inside the table 3 so that the wafer W can be heated to a predetermined temperature. The heater 5 is connected to the heater power supply 4 through wiring arranged in the support column.

  An electrostatic chuck CK that electrostatically attracts the wafer W placed on the table 3 is provided on the upper surface of the table 3. The electrostatic chuck CK is connected to a bias power source BV for applying a bias direct current or high frequency power via a matching unit MG.

  An exhaust pipe 11 for exhausting a processing gas from an exhaust port 11 a below the surface of the wafer W placed on the table 3 is provided at the bottom of the processing container 2. An exhaust device 10 such as a vacuum pump is connected to the exhaust pipe 11 via a pressure control valve PCV. The exhaust device 10 communicates with the inside of the processing container 2 via the pressure control valve PCV. The pressure in the processing container 2 is adjusted to a predetermined pressure by the pressure control valve PCV and the exhaust device 10.

A dielectric window 16 is provided on the ceiling of the processing container 2 via a seal 15 such as an O-ring for ensuring airtightness. The dielectric window 16 is made of a dielectric material such as quartz, alumina (Al ₂ O ₃ ), or aluminum nitride (AlN), and is permeable to microwaves.

  A disk-shaped slot plate 20 is provided on the upper surface of the dielectric window 16. The slot plate 20 is made of a conductive material, for example, copper plated or coated with Ag, Au or the like. In the slot plate 20, for example, a plurality of T-shaped or L-slot shaped slots 21 are arranged concentrically.

A dielectric plate 25 for compressing the wavelength of the microwave is disposed on the upper surface of the slot plate 20. The dielectric plate 25 is made of a dielectric such as quartz (SiO ₂ ), alumina (Al ₂ O ₃ ), or aluminum nitride (AlN). The dielectric plate 25 is covered with a conductive cover 26. An annular heat medium passage 27 is provided in the cover 26. The cover 26 and the dielectric plate 25 are adjusted to a predetermined temperature by the heat medium flowing through the heat medium flow path 27. Taking a microwave having a wavelength of 2.45 GHz as an example, the wavelength in vacuum is about 12 cm, and the wavelength in the dielectric window 16 made of alumina is about 3 to 4 cm.

  A coaxial waveguide 30 that propagates microwaves is connected to the center of the cover 26. The coaxial waveguide 30 includes an inner conductor 31 and an outer conductor 32, and the inner conductor 31 passes through the center of the dielectric plate 25 and is connected to the center of the slot plate 20.

  A microwave generator 35 is connected to the coaxial waveguide 30 via a mode converter 37 and a rectangular waveguide 36. In addition to 2.45 GHz, microwaves such as 860 MHz, 915 MHz, and 8.35 GHz can be used as the microwave.

  The microwave generated by the microwave generator 35 propagates to the rectangular waveguide 36, the mode converter 37, the coaxial waveguide 30, and the dielectric plate 25 as a microwave introduction path. The microwave propagated to the dielectric plate 25 is supplied into the processing container 2 through the dielectric window 16 from the multiple slots 21 of the slot plate 20. An electric field is formed below the dielectric window 16 by the microwave, and the processing gas in the processing container 2 is turned into plasma.

  The lower end of the inner conductor 31 connected to the slot plate 20 is formed in a truncated cone shape. Thereby, the microwave is efficiently propagated from the coaxial waveguide 30 to the dielectric plate 25 and the slot plate 20 without loss.

  The characteristics of the microwave plasma generated by the radial line slot antenna is that a plasma having a relatively high electron temperature generated just below the dielectric window 16 (called a plasma excitation region) diffuses and directly above the wafer W (diffuse plasma). In the region), the plasma has a low electron temperature of about 1-2 eV. That is, unlike plasma of a parallel plate or the like, the plasma electron temperature distribution is clearly generated as a function of the distance from the dielectric window 16. More specifically, the electron temperature of several eV to about 10 eV immediately below the dielectric window 16 attenuates to about 1 to 2 eV on the wafer W. Since the processing of the wafer W is performed in a region where the electron temperature of plasma is low (diffusion plasma region), the wafer W is not seriously damaged such as a recess. When the processing gas is supplied to a region where the plasma electron temperature is high (plasma excitation region), the processing gas is easily excited and dissociated. On the other hand, when the processing gas is supplied to a region where the plasma electron temperature is low (plasma diffusion region), the degree of dissociation can be suppressed as compared with the case where the processing gas is supplied to the vicinity of the plasma excitation region.

  In the center of the dielectric window 16 on the ceiling of the processing container 2, a central introducing portion 55 for introducing a processing gas into the central portion of the wafer W is provided. A processing gas supply path 52 is formed in the inner conductor 31 of the coaxial waveguide 30. The central introduction part 55 is connected to the supply path 52.

  The center introducing portion 55 includes a columnar block 57 that is fitted into a cylindrical space portion 43 (see FIG. 8) provided at the center of the dielectric window 16, a lower surface of the inner conductor 31 of the coaxial waveguide 30, and a block A tapered space 143a (see FIG. 8) in which a gas reservoir 60 spaced at an appropriate interval from the upper surface of 57 and a cylindrical space having a gas ejection opening 59 at the tip are continuous. Consists of The block 57 is made of a conductive material such as aluminum and is electrically grounded. The block 57 is formed with a plurality of central introduction ports 58 (see FIG. 3) penetrating in the vertical direction.

In FIG. 3, the gas ejection opening 59 is shown larger than the actual size so that the central inlet 58 can be observed. The shape of the space portion 143a is not limited to the tapered shape, and may be a simple cylindrical shape. In this case, the size of the gas ejection opening 59 is increased as shown in FIG. The planar shape of the central introduction port 58 is formed in a perfect circle or a long hole in consideration of necessary conductance and the like. The aluminum block 57 is coated with anodized alumina (Al ₂ O ₃ ), yttria (Y ₂ O ₃ ), or the like.

  The processing gas supplied from the supply path 52 penetrating the inner conductor 31 to the gas reservoir 60 diffuses in the gas reservoir 60, and then downwards from the plurality of central inlets 58 of the block 57 and at the center of the wafer W. It is jetted toward.

  Inside the processing container 2, a ring-shaped peripheral introducing portion 61 for supplying a processing gas to the peripheral portion of the wafer W is disposed so as to surround the periphery above the wafer W. The peripheral introduction part 61 is arranged below the central introduction port 58 arranged on the ceiling part and above the wafer W placed on the table 3. The peripheral introduction portion 61 is a hollow pipe formed in an annular shape, and a plurality of peripheral introduction ports 62 are opened at a certain interval in the circumferential direction on the inner peripheral side thereof. The peripheral inlet 62 injects the processing gas toward the center of the peripheral inlet 61. The peripheral introduction part 61 is made of quartz, for example. A supply path 53 made of stainless steel penetrates the side surface of the processing container 2. The supply path 53 is connected to the peripheral introduction part 61. The processing gas supplied from the supply path 53 to the inside of the peripheral introduction part 61 diffuses in the space inside the peripheral introduction part 61 and is then injected from the plurality of peripheral introduction ports 62 toward the inside of the peripheral introduction part 61. . The processing gas sprayed from the plurality of peripheral introduction ports 62 is supplied to the upper periphery of the wafer W. Instead of providing the ring-shaped peripheral introduction portion 61, a plurality of peripheral introduction ports 62 may be formed on the inner surface of the processing container 2.

  FIG. 2 is a block diagram showing a detailed structure of the gas supply source.

  A gas supply source 100 that supplies a processing gas into the processing container 2 includes a common gas source 41 and an additive gas source 42. The common gas source 41 and the additive gas source 42 supply process gases corresponding to the plasma etching process and the plasma CVD process.

  A common gas line 45 is connected to the common gas source 41, and the common gas line 45 is connected to the flow splitter 44. The flow splitter 44 is provided in the common gas line 45 and branches the common gas line 45 into first and second branch common gas lines 46 and 47. The flow splitter 44 can adjust the ratio of the flow rate of the gas flowing through the first and second branch common gas lines 46 and 47. Here, the first branch common gas line 46 is connected to the central introduction part 55 (see FIG. 1) via the supply path 52, and supplies the central introduction gas Gc to the central introduction part 55. The second branch common gas line 47 is connected to the peripheral introduction part 61 (see FIG. 1) via the supply path 53, and supplies the peripheral introduction gas Gp to the peripheral introduction part 61.

  The additive gas source 42 is connected to the second branch common gas line 47 via the additive gas line 48. The additive gas source 42 can also be connected to the first branch common gas line 46 via the additive gas line 48 '. The additive gas source 42 may be connected to both branch common gas lines 46 and 47 via additive gas lines 48 and 48 ′.

The common gas source 41 includes a plurality of gases G ₁₁ , G ₁₂ , G ₁₃ , and G _1x , and is provided with flow rate control valves 41a, 41b, 41c, and 41x that control the flow rate of each gas. Valves V that open and close the line passage are provided before and after the lines connected to the flow control valves 41a, 41b, 41c, and 41x. The flow control valves 41a, 41b, 41c, and 41x are connected to the common gas line 45 through the respective valves V.

The additive gas source 42 includes a plurality of additive gases G ₂₁ , G ₂₂ , G ₂₃ , and G _2x , and flow rate control valves 42 a, 42 b, 42 c, and 42 _x that control the flow rate of each gas are provided. Valves V for opening and closing the line passage are provided before and after the lines connected to the flow control valves 42a, 42b, 42c, and 42x. The flow control valves 42a, 42b, 42c, and 42x are connected to the additive gas line 48 via the respective valves V.

  The controller CONT shown in FIG. 1 controls the flow rate control valves 41a, 41b, 41c, 41x, 42a, 42b, 42c, 42x together with various valves V in the gas supply source, and finally the branch common gas lines 46, 47. The partial pressure ratio of the specific gas contained in the gases Gc and Gp flowing in the gas is controlled. The controller CONT adjusts the flow rate of each gas, and determines the flow rate and partial pressure of each common gas type supplied to the flow splitter 44. In this apparatus, the partial pressure for each gas type of the central introduction gas Gc supplied to the central portion of the wafer W and the peripheral introduction gas Gp supplied to the peripheral portion and the gas type itself can be changed. Various characteristics can be changed.

As the gas G _1x used for the common gas source 41, a rare gas (such as Ar) can be used, but other additive gases can also be used.

In addition, when etching a silicon-based film such as polysilicon, Ar gas, HBr gas (or Cl ₂ gas), O ₂ gas is supplied as additive gases G ₂₁ , G ₂₂ , G ₂₃ , and SiO ₂ or the like. When etching the oxide film, Ar gas, CHF-based gas, CF-based gas, and O ₂ gas are supplied as the additive gases G ₂₁ , G ₂₂ , G ₂₃ , and G _2x to etch the nitride film such as SiN. At that time, Ar gas, CF-based gas, CHF-based gas, and O ₂ gas are supplied as additive gases G ₂₁ , G ₂₂ , G ₂₃ , and G _2x .

As the CHF-based gas _{CH 3 (CH 2) 3 CH} 2 F, CH 3 (CH 2) 4 CH 2 F, CH 3 (CH 2) 7 CH 2 F, CHCH 3 F 2, CHF 3, CH 3 Examples thereof include F and CH ₂ F ₂ .

Examples of the CF-based gas include C (CF ₃ ) ₄ , C (C ₂ F ₅ ) ₄ , C ₄ F ₈ , C ₂ F ₂ , and C ₅ F ₈ , but dissociation suitable for etching. From the viewpoint of obtaining seeds, C ₅ F ₈ is preferable.

  In this apparatus, the common gas source 41 and the additive gas source 42 can supply the same type of gas, and the common gas source 41 and the additive gas source 42 can supply different types of gas.

In order to suppress the dissociation of the etching gas, the plasma excitation gas may be supplied from the common gas source 41 and the etching gas may be supplied from the additive gas source 42. For example, when etching a silicon-based film, only Ar gas is supplied as plasma excitation gas from the common gas source 41, and only HBr gas and O ₂ gas are supplied as etching gas from the additive gas source 42. .

The common gas source 41 further supplies a cleaning gas such as O ₂ and SF _{6 and} other common gases.

  Here, for the purpose of uniform plasma generation and in-plane uniform wafer W processing, the branch ratio of the common gas is adjusted by the flow splitter 44, and the central inlet 58 (see FIG. 3) and the peripheral inlet 61 (see FIG. 3). The technique for adjusting the amount of gas introduced from 1) is called RDC (Radial Distribution Control). RDC is represented by the ratio between the amount of gas introduced from the central inlet 58 and the amount of gas introduced from the peripheral inlet 61. A common RDC is a case where the gas types introduced into the central introduction portion 55 and the peripheral introduction portion 61 are common. The optimum RDC value is experimentally determined depending on the type of film to be etched and various conditions. On the other hand, what supplies additional gas to the center introduction part 55 or the periphery introduction part 61 is called ARDC (Advanced Radial Distribution Control).

  In the etching process, by-products (etched residues and deposits) are generated according to the etching. Therefore, in order to improve the gas flow in the processing container 2 and promote the discharge of by-products to the outside of the processing container, gas introduction from the central introduction part 55 and gas introduction from the peripheral introduction part 61 are alternately performed. Is being considered to do. This can be realized by switching the RDC value in terms of time. For example, the step of introducing a large amount of gas into the central portion of the wafer W and the step of introducing a large amount of gas into the peripheral portion are repeated at a predetermined cycle, and the by-product is swept out of the processing container 2 by adjusting the air flow. It is intended to achieve a more uniform etching rate.

  FIG. 4 is an exploded perspective view of the structure near the slot plate.

  The lower surface of the dielectric window 16 (the surface provided with the recesses) is attached to the plasma processing apparatus 11 so as to be placed on the surface of the annular member 19 constituting a part of the side wall of the processing container 2. A slot plate 20 is provided on the upper surface of the dielectric window 16, and a dielectric plate 25 is provided on the slot plate 20. The planar shapes of the dielectric window 16, the slot plate 20, and the dielectric plate 25 are circular, and their center positions are located on the same axis (Z axis).

  The slot plate 20 has slots having various patterns. In the figure, for the sake of clarity of explanation, the slot plate 20 omits the description of the slot, and instead is shown in FIG. .

  FIG. 5 is a plan view of the slot plate 20.

  The slot plate 20 has a thin plate shape and a disk shape. Both surfaces of the slot plate 20 in the thickness direction are flat. The slot plate 20 is provided with a plurality of slots 132 penetrating in the plate thickness direction. The slot 132 is formed such that a first slot 133 that is long in one direction and a second slot 134 that is long in a direction perpendicular to the first slot 133 are adjacent to each other. Specifically, two adjacent slots 133 and 134 are paired and arranged so as to be substantially L-shaped with the center portion interrupted. That is, the slot plate 20 has a configuration including a slot pair 140 including a first slot 133 extending in one direction and a second slot 134 extending in a direction perpendicular to the one direction. Note that an example of the slot pair 140 is illustrated by a region indicated by a dotted line in FIG.

In this embodiment, the opening width of the first slot 133, that is, the length between the wall portion 130a on one side extending in the longitudinal direction and the wall portion 130b on the other side extending in the longitudinal direction in the first slot 133. W ₁ is configured such that the 12 mm. On the other hand, the longitudinal length of the first slot 133 shown by the length W ₂ in FIG. 5, i.e., the longitudinal direction of the other side in the longitudinal direction of one side of the end portion 130c and the first slot 133 of the first slot 133 the length _{W 2} between the end 130d of is configured such that the 35 mm. These widths W ₁ and W ₂ can allow a change of ± 10%, but even if they are outside this range, they function as an apparatus. For the first slot 133, the ratio W1 / W2 of the length in the short direction to the length in the long direction is 12/35 = 0.34, which is about 1/3. The opening shape of the first slot 133 and the opening shape of the second slot 134 are the same. That is, the second slot 134 is obtained by rotating the first slot 133 by 90 degrees. It should be noted that the length ratio W1 / W2 is less than 1 when configuring the slot as a slot.

  The slot pair 140 is roughly divided into an inner peripheral slot pair group 135 disposed on the inner peripheral side and an outer peripheral slot pair group 136 disposed on the outer peripheral side. The inner peripheral slot pair group 135 is seven slot pairs 140 provided in the inner region of the imaginary circle indicated by the alternate long and short dash line in FIG. The outer peripheral side slot pair group 136 is 28 pairs of slots 140 provided in the outer region of the imaginary circle indicated by the one-dot chain line in FIG. In the inner peripheral slot pair group 135, the seven pairs of slots 140 are arranged at equal intervals in the circumferential direction.

  With this configuration, one slot of the seven pairs of slots 140 arranged in the inner circumferential slot pair group 135 is arranged at a position corresponding to the position where the second concave portion made of circular dimples is provided. Can be aligned. In the outer peripheral side slot pair group 136, 28 pairs of slots 140 are arranged at equal intervals in the circumferential direction. A through hole 137 is also provided in the radial center of the slot plate 20.

  A reference hole 139 is provided in a region on the outer diameter side of the outer peripheral slot pair group 136 so as to penetrate in the plate thickness direction so as to facilitate positioning of the slot plate 20 in the circumferential direction. That is, using the position of the reference hole 139 as a mark, the slot plate 20 is positioned in the circumferential direction with respect to the processing container 2 and the dielectric window 16. The slot plate 20 has rotational symmetry about the radial center 138 except for the reference hole 139.

  Each of the slot pairs constituting the outer peripheral side slot pair group 136 includes slots 133 ′ and 134 ′, and their positions and structures are the same as those of the slots 133 and 134 except that they are positioned on the outer periphery. Same as position and structure.

  The structure of the slot plate 20 will be described in detail. The first slot group 133 located at the first distance R1 (indicated by the circle R1) from the center of gravity position 138 of the slot plate 20 and the second distance R2 (circle) from the center of gravity position 138. A second slot group 134 located at R1), a third slot group 133 'located at a third distance R3 (shown by circle R3) from the center of gravity position 138, and a fourth distance R4 (circle R4) from the center of gravity position 138. 4th slot group 134 'located in this.

  Here, the relationship of 1st distance R1 <2nd distance R2 <3rd distance R3 <4th distance R4 is satisfy | filled. The diameter (line segment R) extending from the gravity center position 148 of the slot plate toward the target slot (any one of 133, 134, 133 ′, and 134 ′) and the angle formed by the longitudinal direction of the slot are as follows. Thru | or 4th slot group 133,134,133 ', and it is the same for every slot group in 134'.

  The slot 133 of the first slot group and the slot 134 of the second slot group located on the same diameter (line segment R) extending from the gravity center position 138 of the slot plate 20 extend in different directions (in this example, orthogonal to each other). The slot 133 ′ of the third slot group and the slot 134 ′ of the fourth slot group located on the same diameter (line segment R) extending from the gravity center position 138 of the slot plate 20 extend in different directions. (In this example, they are orthogonal). The number of slots 133 in the first slot group and the number of slots 134 in the second slot group are the same number N1, and the number of slots 133 ′ in the third slot group and the number of slots 134 ′ in the fourth slot group are , The same number N2.

  Here, N2 is an integer multiple of N1, and it is possible to generate plasma with high in-plane symmetry.

  FIG. 6 is a plan view of the dielectric window, and FIG. 8 is a cross-sectional view of the dielectric window.

  The dielectric window 16 is substantially disc-shaped and has a predetermined plate thickness. The dielectric window 16 is made of a dielectric, and specific examples of the material of the dielectric window 16 include quartz and alumina. A slot plate 20 is provided on the upper surface 159 of the dielectric window 16.

  At the center in the radial direction of the dielectric window 16, a through hole 142 is provided that penetrates in the plate thickness direction, that is, the vertical direction on the paper surface. Of the through hole 142, the lower region serves as a gas supply port in the central introduction portion 55, and the upper region serves as a recess 143 in which the block 57 of the central introduction portion 55 is disposed. The radial center axis 144a of the dielectric window 16 is indicated by a one-dot chain line in FIG.

  Of the dielectric window 16, a radially outer region of the lower flat surface 146, which is a side that generates plasma when the plasma processing apparatus is provided, is connected in a ring shape, and the dielectric window 16 has an inner thickness direction. An annular first concave portion 147 that is recessed in a tapered shape toward the side is provided. The flat surface 146 is provided in the central region in the radial direction of the dielectric window 16. On the central flat surface 146, circular second recesses 153a to 153g are formed at equal intervals along the circumferential direction. The annular first recess 147 is tapered from the outer diameter region of the flat surface 146 toward the outer diameter side, specifically, the inner tapered surface 148 that is inclined with respect to the flat surface 146 and the outer diameter from the inner tapered surface 148. Straight flat in the radial direction toward the side, that is, a flat bottom surface 149 extending parallel to the flat surface 146, and a taper shape toward the outer diameter side from the bottom surface 149, specifically, an outer side extending inclined with respect to the bottom surface 149 A tapered surface 150 is used.

  The angle of the taper, that is, for example, the angle defined in the direction in which the inner tapered surface extends with respect to the bottom surface 149 and the angle defined in the direction in which the outer tapered surface 50 extends with respect to the bottom surface 149 are arbitrarily determined. In this embodiment, it is configured similarly at any position in the circumferential direction. The inner tapered surface 148, the bottom surface 149, and the outer tapered surface 150 are formed so as to be connected with smooth curved surfaces. In addition, the outer diameter region of the outer tapered surface 150 is provided with an outer peripheral plane 152 that extends straight in the radial direction toward the outer diameter side, that is, parallel to the flat surface 146. The outer peripheral plane 152 serves as a support surface for the dielectric window 16.

  That is, the dielectric window 16 is attached to the processing container 2 such that the outer peripheral plane 152 is placed on the upper end surface provided in the inner diameter side region of the annular member 19 (see FIG. 4).

  An annular first recess 147 forms a region in which the thickness of the dielectric window 16 is continuously changed in a radially outer region of the dielectric window 16, so that the dielectric is suitable for various process conditions for generating plasma. A resonant region having the thickness of the window 16 can be formed. Then, high stability of plasma in the radially outer region can be ensured according to various process conditions.

  Here, in the dielectric window 16, a second recess 153 (153 a to 153 g) that is recessed from the flat surface 146 toward the inner side in the plate thickness direction is provided in the radially inner region of the annular first recess 147. ing. The planar shape of the second recess 153 is circular, the inner side surface forms a cylindrical surface, and the bottom surface is flat. Since the circular shape is a polygon having infinite corners, the planar shape of the second recess 153 can be considered to be a polygon having finite corners. However, when the planar shape is circular, since the equivalence of the shape from the center is high, stable plasma is generated.

  In this embodiment, a total of seven second recesses 153 are provided, which is the same as the number of inner slot pairs. The seven second recesses 153a, 153b, 153c, 153d, 153e, 153f, and 153g have the same shape. That is, the recesses of the second recesses 153a to 153g, the size thereof, the diameter of the holes, and the like are configured equally. The seven second recesses 153a to 153g are arranged at intervals so as to have rotational symmetry about the radial center of gravity 156 of the dielectric window 16. The centers 157a, 157b, 157c, 157d, 157e, 157f, and 157g of the seven second recesses 153a to 153f each having a round hole shape are as follows. It is located on a circle 158 centered on the radial center 156. That is, when the dielectric window 16 is rotated 51.42 degrees (= 360 degrees / 7) around the radial center 156, it is configured to have the same shape as before the rotation. The circle 158 is indicated by a one-dot chain line in FIG. 4. The circle 158 has a diameter of 154 mm, and the second recesses 153 a to 153 g have a diameter of 30 mm.

  The depth of the second recess 153 (153a to 153g), that is, the distance between the flat surface 146 and the bottom surface 155 indicated by the length L3 in FIG. 8 is appropriately determined, and is 32 mm in this embodiment. . The diameter of the concave portion 153 and the distance from the bottom surface of the concave portion 153 to the upper surface of the dielectric window are set to ¼ of the wavelength λg of the microwave introduced into the concave portion. In this embodiment, the diameter of the dielectric window 16 is about 460 mm. Although the diameter of the circle 158, the diameter of the recess 153, the diameter of the dielectric window 16, and the depth of the recess 153 can be allowed to be changed by ± 10%, the conditions under which the apparatus operates are limited to this. However, if the plasma is confined in the recess, the device functions. When the value of the diameter and depth of the concave portion close to the center is increased, the plasma density is larger on the center side than on the periphery, so that the balance between them can be adjusted.

  By the second recesses 153a to 153g, the microwave electric field can be concentrated in the recess, and strong mode fixing can be performed in the radially inner region of the dielectric window 16. In this case, even if the process conditions are variously changed, a strong mode-fixed region in the radially inner region can be secured, a stable and uniform plasma can be generated, and the in-plane uniformity of the substrate throughput Can be increased. In particular, since the second recesses 153a to 153g have rotational symmetry, high axial symmetry with strong mode fixing can be ensured in the radially inner region of the dielectric window 16, and the generated plasma is also high. Has axial symmetry.

  As described above, the dielectric window 16 having such a configuration has a wide process margin and the generated plasma has high axial symmetry.

  FIG. 7 is a plan view of an antenna in which a slot plate and a dielectric window are combined. This figure is a view of the radial line slot antenna as viewed from below along the Z-axis in FIG.

  In plan view, a portion of the outer tapered surface 150 and the slot 134 'belonging to the fourth slot group (fourth slot group from the inner side) partially overlap. The annular flat bottom surface 149 and the slot 133 'belonging to the third slot group (third slot group from the inside) overlap.

  In plan view, the inner tapered surface and the slot 134 belonging to the second slot group (second slot group from the inner side) overlap. Further, all the slots 133 belonging to the innermost first slot group are located on the flat surface 146. Furthermore, the center of gravity of the second recess 153 overlaps with the slot 133.

  FIG. 14 is a perspective view (a) and a sectional view (b) in the vicinity of the slot 133 and the recess 153.

  As shown in FIG. 14A, the slot 133 is located immediately above the recess 153, and when the microwave is introduced, a plasma PS is generated in the recess 153 by an electric field generated in the width direction of the slot 133 ( FIG. 14 (b)).

  FIG. 15 is a diagram illustrating a positional relationship between the slots and the second recesses.

  FIG. 15A shows a case where the position of the center of gravity G2 of the recess 153 is set to a position where the electric field E from the slot 133 is selectively introduced. By introducing the microwave, the electric field E is generated in the width direction of the slots 133 and 134. In this example, the gravity center position G1 of the slot 133 and the gravity center position G2 of the second recess 153 coincide with each other, and the gravity center position G2 of the second recess 153 overlaps with the slot 133. In this case, since the plasma is securely fixed to the second recess 153, the plasma fluctuation is small, and the in-plane fluctuation of the plasma is small even when various conditions change. In particular, since the position where the recess 153 is formed is on the central flat surface 146 (see FIG. 7), the equivalence of the surface around one recess 153 is high, and the degree of plasma fixation is increased.

  On the other hand, FIG. 15B shows a case where the position of the center of gravity G2 of the recess 153 is set to a position where the electric field E from both the slots 133 and 134 is introduced. In other words, in FIG. 15B, the gravity center position G1 of the slot 133 and the gravity center G2 of the second recess 153 are separated from each other, and the gravity center position G2 of the second recess 153 overlaps the slot 133. Shows no case. In this case, it is more difficult for the microwave to enter the recess 153 than in the case of FIG. 15A, so that the plasma density may be lowered and the generation of plasma may fluctuate.

  Next, another slot plate will be described.

  FIG. 9 is a plan view of another slot plate.

This slot plate is a view of the slot plate 20 in which the number of slots is reduced and the opening width of the slot 167 is narrower than that described above, as viewed from the plate thickness direction. The opening width of the slot 167, i.e., out of the slot 167, the length W ₃ between the wall portion 168b on the other side extending in the wall portion 168a and the longitudinal direction of one side extending in the longitudinal direction, configured to be 6mm Has been. The length W ₃ being approximately half the length W ₁ in the case of the slot 133 of the slot plate of the above.

On the other hand, the length in the longitudinal direction of the slot 167 indicated by the length W ₄ , that is, the length between the end portion 168 c in the longitudinal direction of the slot 167 and the end portion 168 d in the longitudinal direction of the slot 167. W ₄ is configured to be 50mm. The length W ₄ are the same as the length W ₂ in the case of a slot 133 provided on the slot plate of the above. For the slot 167, the ratio W ₃ / W ₄ of the length in the lateral direction to the length in the longitudinal direction is 6/50, which is about 1/8. The other configuration of the slot and the like are the same as those of the slot plate 20 shown in FIG.

  Here, with respect to the opening shape of the slot, the wider the electric field of the introduced microwave is, the stronger the resistance to circumferential displacement is.

  If the slot opening width becomes narrower, microwaves can be radiated more strongly, but the position of the slot in mounting the slot plate is shifted in the circumferential direction, and the microwave radiation is extremely disturbed due to disturbance of microwave propagation. May be weak. On the other hand, if the slot opening width is widened, the microwave radiation is weakened as a whole, but in response to the displacement of the slot position in the circumferential direction and the disturbance of the propagation of the microwave, Microwaves can be emitted without weakening. That is, the wider the plasma opening width, the higher the plasma stability.

  FIG. 10 is a plan view of a dielectric window according to a comparative example.

  The dielectric window 16 according to the comparative example does not include the second recess formed on the flat surface 146.

FIG. 11 is a graph showing the relationship between the position X (mm) and the electron concentration Ne (/ cm ³ ).

Example 1 in the graph shows data when the antenna shown in FIG. 7 is used in the apparatus shown in FIG. 1 and a microwave (1000 W) is introduced into the antenna. Example 2 shows the antenna shown in FIG. 9 shows data when a microwave (2000 W) is introduced, and in the comparative example, the slot plate 20 of FIG. 9 is combined with the dielectric window 16 shown in FIG. 10, and this is combined with the microwave (1500 W). Data is shown when. Ar and O ₂ were introduced at a ratio of 1: 1 from the central introduction part, and the pressure in the processing container was set to 10 m (Torr) = 1.3 Pa.

In any case, as the position X from the center of the antenna increases, the electron density Ne (/ cm ³ ) of the generated plasma tends to decrease, but in the case of Examples 1 and 2, it is close to the center. In the region, the electron concentration is flat and the left / right symmetry is higher than that of the comparative example. This indirectly indicates that the plasma is satisfactorily fixed to the second recess as well as the annular first recess, and that the above-described structure is effective for generating stable and uniform plasma. confirmed.

FIG. 12 is a graph showing the relationship between the position (mm) and the etching rate ER (nm / min). The etching object is SiO ₂ . In this graph, in addition to the X-axis and the Y-axis, an axis V-axis and a W-axis that form 45 degrees with each other are shown.

FIG. 12A shows data when the antenna of the comparative example is used. The pressure in the processing vessel is 10 m (Torr) = 1.3 Pa, the microwave power is 2000 (W), the flow rate of Ar / C ₅ F ₈ is 600/10 (sccm), Ar gas is introduced 20% from the central introduction part, the peripheral introduction 80% was introduced from the part, and 10 sccm of C ₅ F ₈ was introduced into the processing container from the peripheral introduction part. The average etching rate ER is 71 nm / min, and the standard deviation Σ is 9.1%.

FIG.12 (b) has shown the data at the time of using the antenna of FIG. The processing vessel internal pressure is 1.3 Pa, the microwave power is 2000 (W), the total flow rate of Ar / C ₅ F ₈ is 600/10 (sccm), and these mixed gases are branched at 20%: 80%. Each was introduced into the processing vessel from the central introduction part and the peripheral introduction part. The average etching rate ER is 70 nm / min, and the standard deviation Σ is 4.7%.

FIG.12 (c) has shown the data at the time of using the antenna of FIG. The processing vessel internal pressure is 1.3 Pa, the microwave power is 2000 (W), the total flow rate of Ar / C ₅ F ₈ is 600/10 (sccm), Ar is 122 (sccm) from the central introduction part, and from the peripheral introduction part Supplied Ar / C ₅ F ₈ at 478/10 (sccm). The average etching rate ER is 69 nm / min, and the standard deviation Σ is 3.1%.

  FIG. 13 is a graph showing the relationship between the position (mm) and the etching rate ER (nm / min). The object to be etched is SiN. In this graph, in addition to the X-axis and the Y-axis, an axis V-axis and a W-axis that form 45 degrees with each other are shown.

FIG. 13A shows data when the antenna of the comparative example is used. The pressure in the processing vessel is 10 m (Torr) = 1.3 Pa, the microwave power is 2000 (W), and the flow rate of Ar / C ₅ F ₈ is 600/10 (sccm). Ar gas was introduced 20% from the central introduction part and 80% from the peripheral introduction part, and 10 sccm of C ₅ F ₈ was introduced into the processing vessel from the peripheral introduction part. The average etching rate ER is 11 nm / min, and the standard deviation Σ is 29.1%. The etching selectivity of SiO ₂ to SiN is 6.23.

FIG.13 (b) has shown the data at the time of using the antenna of FIG. The processing vessel internal pressure is 1.3 Pa, the microwave power is 2000 (W), the total flow rate of Ar / C ₅ F ₈ is 600/10 (sccm), and these mixed gases are branched at 20%: 80%. Each was introduced into the processing vessel from the central introduction part and the peripheral introduction part. The average etching rate ER is 13 nm / min, and the standard deviation Σ is 24.6%. The etching selectivity of SiO ₂ to SiN is 5.28.

FIG.13 (c) has shown the data at the time of using the antenna of FIG. The processing vessel internal pressure is 1.3 Pa, the microwave power is 2000 (W), the total flow rate of Ar / C ₅ F ₈ is 600/10 (sccm), Ar is 122 (sccm) from the central introduction part, and from the peripheral introduction part Supplied Ar / C ₅ F ₈ at 478/10 (sccm). The average etching rate ER is 11 nm / min, and the standard deviation Σ is 16.5%. The etching selectivity of SiO ₂ to SiN is 6.28.

As described above, when the antenna shown in FIG. 7 is used, the standard deviation Σ can be reduced in any film etching, and etching with a high selectivity can be performed. Similar results were obtained when the material to be etched was changed to silicon or organic materials. In particular, when C ₅ F ₈ is used as a gas species, the dissociation state can be controlled and a species suitable for etching can be obtained, so that etching can be performed with high accuracy. Dissociation in the plasma processing apparatus depends on τ × Ne × (σ × v). τ is the residence time in the plasma (sec), Ne is the electron concentration (/ cm ³ ) of the plasma, σ is the dissociation cross section (cm ² ), and v is the electron velocity (m / sec).

Note that the dissociation process is different between c-C ₄ F ₈ and L-C ₄ F ₈ . c-C ₄ F ₈ is easily decomposed to form a film composed of many radicals and a polymer, but L-C ₄ F ₈ is dissociated into two CF ₃ CFs to form a dense film. To do. c is cyclic and L is linear.

  As described above, the antenna described above includes the dielectric window 16 and the slot plate 20 provided on one surface of the dielectric window 16, and the other surface of the dielectric window 16 has an annular first recess. And a plurality of second recesses 153 formed in the flat surface 146 so as to surround the center of gravity of the flat surface 146. Further, when viewed from the direction perpendicular to the main surface of the slot plate 20, the gravity center positions of the respective second recesses 153 overlap with each other in the slots 133 of the slot plate 20. When this antenna is used, highly uniform plasma can be generated. Therefore, in a plasma processing apparatus using the antenna, the in-plane uniformity of the processing amount can be increased. Such a plasma processing apparatus can be used not only for etching but also for film deposition.

In the above-described plasma processing method, the common gas source includes a rare gas (Ar), the additive gas source includes C ₅ F ₈ , and the microwave introduction path from the microwave generator. Through which the microwave is supplied to the slot plate to generate plasma on the other side of the dielectric window, and from the common gas source to the central introduction portion through the first branch common gas line, the rare gas (Ar In addition, the substrate on the table is etched by supplying C ₅ F ₈ from the additive gas source to the peripheral introduction portion via the second branch common gas line. . This plasma processing method can increase the in-plane uniformity of the surface treatment amount.

  In the methods shown in FIGS. 12C and 13C, the amount of additive gas supplied to the peripheral introduction part is clarified while changing the flow rate ratio between the central introduction part and the peripheral introduction part. That is, as shown in FIGS. 1 and 2, the plasma processing apparatus for realizing these plasma processes is provided in the common gas line 45 connected to the common gas source 41 and the common gas line 45. 45 is branched into the first and second branch common gas lines 46 and 47, and the flow splitter 44 capable of adjusting the ratio of the flow rate of the gas flowing through the first and second branch common gas lines 46 and 47, and the first branch A central introduction part 55 having a central introduction port connected to the common gas lines 46 and 47 and located above the central part of the substrate placed on the table 3, and connected to the second branch common gas line 47 and above the substrate. A peripheral introduction part 61 having a plurality of peripheral introduction ports 62 arranged along the circumferential direction of the space and positioned below the dielectric window 16, an additive gas source 42, and the first and second branch common gas lines 4. Comprises an additive gas line 48 for connecting the at least one of 47 (48 '), by controlling the flow rate of each gas line, it can be increased in-plane uniformity of the substrate surface processing amount.

  FIG. 16 is a view showing an improved central introduction portion, and this figure shows an improved portion of a region surrounded by a dotted line A in FIG.

  As shown in FIG. 16, the substantially disc-shaped dielectric window 16 is formed with a through hole 16 a extending along the axis X. The dielectric window 16 is formed with a through hole 16a having a substantially constant diameter along the axis X direction. The through hole 16a may have a tapered shape whose diameter decreases downward. In the dielectric window 16, a space 16s is formed above the through hole 16a. The space 16s is defined by, for example, the inner peripheral surface 16b and the bottom surface 16c of the dielectric window 16 extending in the center of the axis X. The dielectric window 16 is formed with an annular groove 16g continuous with the lower peripheral edge of the space 16s.

  The gas supply path (pipe member) 52 is a metal member and is made of, for example, stainless steel. The supply path 52 includes a first portion 52a, a second portion 52b, and a third portion 52c. The first portion 52 a is a tube that extends along the axis X, and is inserted into the inner hole of the inner conductor 31.

  The second portion 52b is continuous with the first portion 52a below the first portion 52a. The second portion 52b has a diameter that is larger than the diameter of the first portion 52a. The second portion 52b is provided with a hole that is continuous with the inner hole of the first portion 52a. The second portion 52b holds the slot plate 20 between the lower end of the inner conductor 31 and the second portion 52b.

  The third portion 52c extends downward continuously from the lower peripheral edge of the second portion 52b, and has a ring shape. The lower end portion of the third portion 52c is accommodated in the groove 16g described above.

The injector 22A is made of a dielectric and is formed integrally with the dielectric window 16 or joined to the dielectric window 16 as a separate member. The injector 22A is located at the center of the dielectric window 16, and the effective area has a substantially disk shape. The injector 22A is made of the same material as that of the dielectric window 16 in the case of integral molding, and can be made of the same material when another member is joined. When the dielectric window 16 and the injector 22A are integrally formed, the generation of a gap between the injector 22A and the dielectric window 16A is more reliably prevented. Injector 22A may be composed of a bulk dielectric material. For the bonding, for example, diffusion bonding can be used. As a dielectric material constituting the injector 22A, for example, a material such as quartz or Y ₂ O ₃ can be used.

  The injector 22A includes two surfaces 22b and 22c extending in a direction intersecting the axis X. The surface 22c faces the surface 22b and faces the processing space S (see FIG. 1). In the injector 22A, one or more through holes 22a extending between the surface 22c and the surface 22b are formed. In the injector 22A having such a shape, for example, when the dielectric window 16 is processed, the bulk dielectric material constituting the dielectric window 16 is machined, and then the crushed layer on the surface is removed by wet etching or the like. Can be manufactured. Removal of the crushed layer may make the injector 22A more chemically stable.

  The injector 22A is located in the space 16s inside the dielectric window 16. More specifically, the injector 22 </ b> A is disposed in a partial space defined by the lower surface of the second portion 52 b of the supply path 52 and the third portion 52 c of the supply path 52.

  The processing gas from the supply path 52 passes through the through hole 22a of the injector 22A, and then is supplied into the processing space S through the through hole 16a of the dielectric window 16. That is, the injector 22A constitutes a path for supplying the processing gas to the processing space S together with the hole 16a of the dielectric window 16. As described above, the processing gas is passed through the injector 22A. However, since the injector 22A is made of a dielectric material, it is chemically stable with respect to the processing gas. Therefore, the generation of particles from the injector 22A can be reduced.

  In the plasma processing apparatus, the third portion 52 c of the supply path 52 constitutes an electric field shielding portion that covers the periphery of the injector 22. This electric field shielding portion makes it difficult for plasma to be generated inside the injector 22A. Therefore, the generation of particles from the injector 22A can be further suppressed.

  As described above, since the injector 22A and the dielectric window 16 are integrated, the generation of a gap between the injector 22A and the dielectric window 16 can be suppressed. Thereby, it is possible to prevent a situation in which the processing gas flows backward from the processing space S or the like to the space 16s through the gap and contaminates the components of the plasma processing apparatus.

  In one embodiment, the 3rd portion 52c which is an electric field shielding part to injector 22A may be constituted as a part of supply channel 52. That is, the electric field shielding portion can be integrated with the processing gas piping to the injector 22A. This simplifies the manufacturing process such as assembly and placement of the electric field shielding part.

  In one embodiment, the third portion 52c, that is, the electric field shielding portion, can extend to a position closer to the processing space S in the axis X direction than the surface 22c of the injector 22A. Thereby, the electric field strength in the space where the injector 22A is disposed is further reduced. As a result, the generation of plasma inside the injector 22A is further suppressed, and the generation of particles from the injector 22A is further suppressed.

  Note that the distance GAP in the axis X direction between the lower end surface of the electric field shielding portion, that is, the lower end surface 52d of the third portion 52c and the surface 22c of the injector 22A, and the electric field strength in the space where the injector 22 is disposed. As a result of the simulation of the relationship, by providing the lower end surface (52d) of the electric field shielding part below the surface 22c of the injector 22A, the electric field strength is reduced, and the generation of plasma inside the injector 22A is effectively suppressed. Confirmed to get.

A protective layer PL1 made of yttria (yttrium oxide (Y ₂ O ₃ )) can be provided on the lower surface of the second portion 52b of the supply path 52 made of stainless steel or the like. Although the protective layer PL1 protects the second portion 52b from plasma and gas, it is preferable to perform a specific treatment on the protective layer PL1 from the viewpoint of particle generation suppression and strength enhancement. That is, by spraying metal yttrium or yttria in an oxygen-containing atmosphere or by spraying yttria in a reduced pressure environment, an electron beam or the like is applied to the protective layer PL1 made of yttria deposited on the lower surface of the second portion 52b. By irradiating the energy beam, the protective layer PL1 is heated and melted, so that it can be made amorphous after cooling. As a result, the protective layer PL1 is modified and enhanced. In this case, the flatness of the protective layer PL1 is also increased and the gaps between the surface particles are filled, so that the surface area is reduced and the resistance to gas and the like is further increased.

  A characteristic of microwave plasma generated by a radial line slot antenna is that a plasma with a relatively high electron temperature of several eV generated just below the dielectric window (called plasma excitation region) diffuses, There is a low electron temperature of about 1-2 eV just above the substrate below 100 mm or more (referred to as diffusion plasma region). That is, the electron temperature distribution of the plasma is generated as a function of the distance from the dielectric window.

  In a radial line slot antenna type plasma etching apparatus, an etching gas is supplied to a low electron temperature region, and the dissociation of the etching gas is controlled (control of the amount of etching species generated in the plasma). The surface chemical reaction of the substrate) is controlled, so that the etching accuracy can be improved and the damage to the substrate is greatly reduced. For example, a device can be manufactured according to the design dimensions such as etching in a spacer forming step, and damage such as a recess can be suppressed from entering the substrate.

  However, with the increase in the size of the substrate to be processed, further improvement in the in-plane uniformity of the substrate surface processing amount is expected. For example, in an etching apparatus using a radial line slot antenna described in Patent Document 2, it is difficult to make the etching rate, the etching shape, and the like in the plane of the substrate constant, and the etching process is performed in the plane of the substrate. Performing uniformly is an issue.

  In order to provide an antenna, a dielectric window, a plasma processing apparatus, and a plasma processing method capable of improving in-plane uniformity of the substrate surface processing amount, the above-described antenna includes a dielectric window and one surface of the dielectric window. The other surface of the dielectric window is formed in the flat surface so as to surround the flat surface surrounded by the annular first recess and the position of the center of gravity of the flat surface. A plurality of second recesses, and the center of gravity of each of the second recesses overlaps in each slot of the slot plate when viewed from a direction perpendicular to the main surface of the slot plate. It is characterized by that.

  When this antenna is used, plasma with high in-plane uniformity can be generated. Therefore, in the plasma processing apparatus using this antenna, the in-plane uniformity of the substrate surface processing amount can be increased.

  In the above-described antenna, the slot plate includes a first slot group located at a first distance from the gravity center position of the slot plate, a second slot group located at a second distance from the gravity center position of the slot plate, and A third slot group located at a third distance from the center of gravity of the slot plate, and a fourth slot group located at a fourth distance from the center of gravity of the slot plate, wherein a first distance <second distance <third The diameter extending from the center of gravity of the slot plate toward the target slot satisfying the relationship of distance <fourth distance and the angle formed by the longitudinal direction of the slot are the respective slots in the first to fourth slot groups. The slots of the first slot group and the slots of the second slot group, which are the same for each group and are located on the same diameter extending from the center of gravity of the slot plate, extend in different directions, The slots of the third slot group and the slots of the fourth slot group located on the same diameter extending from the center of gravity of the lot plate extend in different directions. The number of slots of the first slot group and the slots of the second slot group The number is the same number N1, the number of slots in the third slot group and the number of slots in the fourth slot group are the same and the number N2, and N2 is an integer multiple of N1.

  N2 is an integer multiple of N1, and can generate plasma with high in-plane symmetry.

  In the antenna described above, the planar shape of the second recess is circular.

  When the surface shape is a circle, since the equivalence of the shape from the center is high, stable plasma is generated.

  The above-described plasma processing apparatus includes the above-described antenna, a processing container having the antenna therein, a table provided inside the processing container, facing the other surface of the dielectric window and on which a substrate to be processed is placed. And a microwave introduction path for connecting the microwave generator and the slot plate.

  The plasma processing apparatus using the antenna has high plasma uniformity, and the in-plane uniformity of the substrate surface processing amount can be increased.

  The plasma processing apparatus described above is provided in a common gas line connected to a common gas source, the common gas line, the common gas line is branched into first and second branch common gas lines, and the first and second A flow splitter capable of adjusting the ratio of the flow rate of the gas flowing through the second branch common gas line, and a central inlet connected to the first branch common gas line and located above the central portion of the substrate placed on the table A peripheral introduction having a central introduction portion having a plurality of peripheral introduction ports connected to the second branch common gas line and arranged along a circumferential direction of a space above the substrate and positioned below the dielectric window And an additive gas line connecting the additive gas source and at least one of the first and second branch common gas lines.

  By controlling the flow rate of each gas line, the in-plane uniformity of the substrate surface treatment amount can be increased.

The plasma processing method described above is a plasma processing method using the above-described plasma processing apparatus, wherein the common gas source includes a rare gas, and the additive gas source includes C ₅ F _8. A microwave is supplied from the microwave generator to the slot plate via the microwave introduction path to generate plasma on the other surface side of the dielectric window, and from the common gas source, A rare gas is supplied to the central introduction part via the one branch common gas line, and further, C ₅ F ₈ is supplied from the additive gas source to the peripheral introduction part via the second branch common gas line. To process the substrate on the table.

  This plasma processing method can increase the in-plane uniformity of the surface treatment amount.

  The above-mentioned dielectric window is a dielectric window in which a slot plate is provided on one surface, and the other surface of the dielectric window includes a flat surface surrounded by an annular first recess and a center of gravity of the flat surface. A plurality of second recesses formed in the flat surface so as to surround the position, and when viewed from a direction perpendicular to the main surface of the slot plate, in each slot in the slot plate, And the slot plate has a first slot group located at a first distance from the center of gravity of the slot plate and a second distance from the center of gravity of the slot plate. A second slot group located at a third slot group located at a third distance from the center of gravity of the slot plate, and a fourth slot group located at a fourth distance from the center of gravity of the slot plate, 1st distance <2nd distance <3rd The diameter extending from the center of gravity of the slot plate toward the target slot and the angle formed by the longitudinal direction of the slot is determined by the slot in the first to fourth slot groups. The slots of the first slot group and the slots of the second slot group, which are the same for each group and are located on the same diameter extending from the gravity center position of the slot plate, extend in different directions, and the gravity center position of the slot plate The slots of the third slot group and the slots of the fourth slot group located on the same diameter extending from the same extend in different directions, and the number of slots of the first slot group and the number of slots of the second slot group are the same. The number of slots in the third slot group is the same as the number of slots in the fourth slot group.

  This dielectric window can be used in combination with the slot plate described above.

  W ... wafer (substrate), 2 ... processing vessel, 3 ... table, 11a ... exhaust port, 16 ... dielectric window, 20 ... slot plate, 21 ... slot, 35 ... microwave generator, 41 ... common gas source, 42 ... addition gas source, 44 ... flow splitter, 45 ... common gas line, 46,47 ... branch common gas line, 48 ... addition gas line, 55 ... central introduction part (first gas introduction part), 58 ... central introduction port 61 ... Periphery introduction part (second gas introduction part), 62 ... Periphery introduction port.

Claims (5)

The microwave energy is supplied to the processing chamber is arranged on top of the processing chamber via an antenna having a dielectric window, the process gas supplied into the processing chamber from the gas supply source into a plasma, A plasma processing apparatus for plasma processing a substrate disposed at a lower portion of the processing container,
Comprising at least first and second gas introduction portions for introducing the processing gas supplied from the gas supply source into positions at different distances from the dielectric window ;
The first gas introduction part is a central introduction part having a central introduction port located at a central part of the dielectric window,
The second gas introduction part is a peripheral introduction part that is arranged along the circumferential direction of the space above the substrate and has a plurality of peripheral introduction ports positioned below the dielectric window ,
The antenna is
The dielectric window;
A slot plate provided on one surface of the dielectric window;
With
The other side of the dielectric window is
A flat surface surrounded by an annular first recess;
A plurality of second recesses formed in the flat surface so as to surround the center of gravity of the flat surface;
Have
When viewed from a direction perpendicular to the main surface of the slot plate, the center of gravity of each of the second recesses is located in each slot in the slot plate,
A plasma processing apparatus. The gas supply source has first and second gas sources;
The first gas introduction part is provided on the plasma excitation region side directly below the dielectric window,
The second gas introduction part is provided on the plasma diffusion region side immediately above the substrate,
The plasma excitation region has an electron temperature higher than the plasma diffusion region,
Gas supply is performed from the first gas source to the first and second gas introduction units,
The first or second gas introduction part is supplied with gas from the second gas source,
2. The plasma processing apparatus according to claim 1, wherein the amount of gas supplied to the first and second gas introduction units is changeable so as to change characteristics of plasma processing in the substrate. 3. . 3. The plasma according to claim 1, wherein control is performed to repeat a step of supplying a gas from the first gas introduction unit and a step of supplying a gas from the second gas introduction unit at a predetermined cycle. Processing equipment. A common gas line connected to a common gas source;
A flow splitter which is provided in the common gas line, which branches the common gas line into first and second branch common gas lines, and which can adjust a flow rate ratio of gas flowing through the first and second branch common gas lines. When,
An additive gas line connecting the additive gas source and at least one of the first and second branch common gas lines;
With
The gas supply source includes the common gas source and the additive gas source,
The first gas inlet is connected to said first branch common gas line is the central inlet portion having a central inlet port located above the central portion of the substrate,
The second gas inlet is connected to the second branch the common gas line, the arrayed along the circumferential direction of the substrate above the space, a plurality of said peripheral inlet opening which is located below the dielectric window is the peripheral inlet portion having,
The plasma processing apparatus according to claim 1.   A common gas line connected to a common gas source;
  A flow splitter which is provided in the common gas line, which branches the common gas line into first and second branch common gas lines, and which can adjust a flow rate ratio of gas flowing through the first and second branch common gas lines. When,
  The central introduction part connected to the first branch common gas line and having the central introduction port located above the central part of the substrate placed on a table;
  The peripheral introduction part connected to the second branch common gas line and arranged along the circumferential direction of the space above the substrate, and having a plurality of the peripheral introduction ports located below the dielectric window;
  An additive gas line connecting the additive gas source and at least one of the first and second branch common gas lines;
The plasma processing apparatus according to claim 1, comprising:

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