TW201812885A - Plasma processing apparatus - Google Patents

Abstract

The present invention provides a technology to perform uniform plasma processing in a circumferential direction with respect to a region of the outer circumferential side of a rectangular object substrate. According to the present invention, the plasma processing apparatus (1) performs plasma processing for a rectangular object substrate (G) by capacitively coupled plasma (P) of a processing gas formed between a cathode electrode (14) and a rectangular anode electrode part (3). At this time, the anode electrode part (3) is segmented into a plurality of diametric segmented electrodes (34, 33, 32) towards a diameter, and the diametric segmented electrode (32) on the outer circumferential side is segmented into a corner part segmented electrode (32b) of a corner side and an edge part segmented electrode (32a) of an edge side. Impedance adjustment parts (52, 51) are formed on at least one ground terminal (104) side of the corner and side part segmented electrodes (32b, 32a).

Description

   Plasma processing device   

The present invention relates to a plasma processing apparatus for performing plasma processing of a substrate to be processed using a plasma-treated processing gas.

In a manufacturing process of a flat panel display (FPD) such as a liquid crystal display device (LCD), there is a process such as supplying a plasma-treated processing gas to a rectangular substrate to be processed, that is, a glass substrate, and performing an etching process or Plasma treatment such as film formation treatment. In these plasma treatments, various plasma treatment apparatuses such as a plasma etching apparatus or a plasma CVD apparatus are used.

In addition, in the plasma processing of a rectangular substrate to be processed, it is required to uniformly supply the plasmatized region toward a region on the outer peripheral side of a corner portion including corners around a vertex of the substrate to be processed and edges between the corner portions. Processing gas.

Here, Patent Document 1 describes a parallel-plate-type plasma processing apparatus that opposes an upper electrode and a lower electrode, and mounts a substrate to be processed on the lower electrode. A capacitive coupling formed by applying high-frequency power to one side of the lower electrode causes the processing gas to be plasmatized. The plasma processing apparatus described in Patent Document 1 is provided with a plurality of impedance adjusting sections for impedance adjustment at positions separated from each other in the lateral direction of the upper surface side of the upper electrode of the anode electrode, thereby suppressing the accompanying An unnecessary plasma is generated which is capacitively coupled between the anode electrode and the wall portion of the processing container.

Further, Patent Document 2 describes a technique in which a plasma processing apparatus of a parallel flat plate type that performs plasma processing is mounted on a semiconductor wafer that is a processing object connected to an RF power source and mounted thereon. The counter electrode (equivalent to the cathode electrode) is disposed opposite to the counter electrode (equivalent to the anode electrode), and the counter electrode is divided into regions with different distances from the center to make the impedance different between these regions. A variable impedance section is provided in each area. However, none of these Patent Documents 1 and 2 discloses a technique as follows: When performing a plasma treatment on a rectangular substrate to be processed, the aforementioned corners or edges are uniformly supplied and plasmatized. Processing gas.

    [Prior technical literature]         [Patent Literature]    

[Patent Document 1] Japanese Patent No. 4553247: Patent Application Scope 1, 2, Paragraph 0034, 0041, Figure 8

[Patent Document 2] Japanese Unexamined Patent Publication No. 6-61185: Patent Application Scope Nos. 1 and 2, Paragraphs 0030 to 0031, Figures 1 and 2

The present invention has been made by researchers in view of such circumstances, and an object thereof is to provide a technique for performing a more uniform plasma treatment in a peripheral direction on a region on the outer peripheral side of a rectangular substrate to be processed.

The plasma processing apparatus of the present invention performs plasma processing on a rectangular substrate to be processed in a vacuum-exhausted processing container by plasma processing gas. The plasma processing apparatus is characterized in that: A cathode electrode is provided in the processing container in an insulated state from the processing container, is connected to a high-frequency power source through a matching circuit, and a rectangular substrate to be processed is placed thereon; and an anode electrode portion, The anode electrode portion is arranged to face the cathode electrode in an insulated state from the processing container and has a rectangular planar shape corresponding to the substrate to be processed. The anode electrode portion is formed from the anode electrode portion. When the direction from the center side toward the outer peripheral side is set as the radial direction, the radial direction is divided into a plurality of radial direction split electrodes, and the radial direction split electrodes are connected to the ground terminals in an insulated state. Among the plurality of radial-direction divided electrodes, the radial-direction divided electrode located on the outer peripheral side is divided toward the circumferential direction and divided into the anode electrode portion. The plurality of corner division electrodes on the side and the plurality of side division electrodes on the side, the corner division electrodes and the side division electrodes are respectively connected to the ground terminal in a state of being insulated from each other. An impedance adjustment unit is provided on the ground end side of at least one of the corner division electrode and the side division electrode, and the impedance adjustment unit is used to adjust from the cathode electrode to each corner division electrode or side via a plasma. Impedance of the circuit of the ground terminal of the split electrode.

The present invention relates to a plasma processing apparatus of a parallel flat plate type that performs plasma processing of a rectangular substrate to be processed, and is directed to an outer peripheral side of an anode electrode portion arranged in a rectangular shape in a plane shape facing the substrate to be processed. Radially divided electrodes are divided into a plurality of corner divided electrodes located on the corner side and a plurality of side divided electrodes located on the side side, and are provided to adjust the impedance of the circuit from the cathode electrode to the ground through the plasma. Impedance adjustment section. As a result, a uniform plasma treatment can be performed on the substrate to be processed at a position corresponding to the corner portion and the side portion.

G‧‧‧ substrate

P, P’‧‧‧ Plasma

1‧‧‧ Plasma treatment device

13‧‧‧mounting table

151‧‧‧ Matcher

152‧‧‧The first high-frequency power supply

161‧‧‧ Matcher

162‧‧‧The second high frequency power supply

3.3a ~ 3d‧‧‧‧Anode electrode section

32‧‧‧peripheral split electrode

32a‧‧‧Edge split electrode

32b‧‧‧Angle split electrode

33‧‧‧ Intermediate split electrode

34‧‧‧ inside split electrode

503, 504‧‧‧‧ ammeter

51 ~ 54‧‧‧Impedance adjustment section

6‧‧‧Control Department

[Fig. 1] A longitudinal sectional side view of a plasma processing apparatus according to an embodiment.

[Fig. 2] A plan view of an anode electrode portion provided in the plasma processing apparatus.

[Fig. 3] An operation diagram of a conventional plasma processing apparatus.

4 is a plan view showing a first modified example of the anode electrode portion.

5 is a plan view showing a second modified example of the anode electrode portion.

[Fig. 6] A plan view of an anode electrode portion used in the experiment.

[Fig. 7] An explanatory diagram showing a result of impedance adjustment on the inner divided electrode side.

FIG. 8 is an explanatory diagram showing a result of impedance adjustment on the middle divided electrode side.

FIG. 9 is an explanatory diagram showing a result of an etching process using a divided electrode.

10 is an explanatory diagram showing a relationship between a current flowing through an inner divided electrode and a consumption amount of a test piece.

FIG. 11 is an explanatory diagram showing a relationship between a current flowing through the middle division electrode and a consumption amount of a test piece.

The plasma processing apparatus 1 of this example is a metal film, an ITO (Tin-doped lndium Oxide) film, and an oxide film that can be used to form a thin film transistor on a rectangular substrate to be processed, for example, a substrate G for FPD. Various plasma treatments, such as a film formation process of a film, etc., or an etching process which etches these films, an ashing process of a photoresist film. Here, examples of the FPD include a liquid crystal display (LCD), an electroluminescence (EL) display, a plasma display panel (PDP), and the like. In addition, the plasma processing apparatus 1 is not limited to the substrate G for FPD, and the above-mentioned various plasma processes can also be used for the substrate G for solar cell panels.

Hereinafter, referring to FIGS. 1 and 2, a plasma processing apparatus 1 configured as an etching apparatus will be described. The etching apparatus is a large-sized glass formed on a short side with a length of 730 mm or more and a long side with a length of 920 mm or more. Etching of a film on a substrate (hereinafter simply referred to as a substrate) G. As shown in FIG. 1, the plasma processing apparatus 1 is provided with a container body 10 in the shape of a prism formed of a conductive material such as aluminum whose inner wall surface is anodized, and the container body 10 is electrically grounded. An opening is formed on the upper surface of the container body 10 (the frame portion 11 described later), and the opening is air-tightly closed by the anode electrode portion 3. The space surrounded by the container body 10 and the anode electrode portion 3 is a processing space 100 for the substrate G, and the upper side of the anode electrode portion 3 is provided with conductivity such as impedance adjustment portions 51 and 52 described later. The upper cover 50 made of a material is covered. Further, a side wall of the processing space 100 is provided with a loading / unloading port 101 for loading and unloading the substrate G and a gate valve 102 for opening and closing the loading / unloading port 101.

On the lower side of the processing space 100, a mounting table 13 for mounting the substrate G is provided so as to face the anode electrode section 3 up and down. The mounting table 13 is made of a conductive material such as aluminum whose surface is anodized. The substrate G placed on the mounting table 13 is sucked and held by an electrostatic fixture (not shown). The mounting table 13 is housed in an insulator frame 14, and is mounted on the bottom surface of the container body 10 via the insulator frame 14.

First and second high-frequency power sources 152 and 162 are connected to the mounting table 13 via matching devices 151 and 161, respectively.

High-frequency power having a frequency in a range of, for example, 10 to 30 MHz is supplied from the first high-frequency power source 152. The electric power supplied from the first high-frequency power source 152 functions to form a high-density capacitive coupling plasma P between the mounting table 13 and the anode electrode portion 3.

On the other hand, the high-frequency power for bias is supplied from the second high-frequency power source 162, for example, a high-frequency power having a frequency in a range of 2 to 6 MHz. With the self-supplied bias generated by the high-frequency power for the bias, ions in the plasma P generated in the processing space 100 can be introduced to the substrate G.

In order to form the plasma P with the anode electrode portion 3, the mounting table 13 that supplies high-frequency power from the first and second high-frequency power sources 152 and 162 corresponds to the cathode electrode of this embodiment. In addition, a plurality of high-frequency power sources (the first high-frequency power source 152 and the second high-frequency power source 162) connected to the mounting table 13 with different frequencies are not necessarily required. For example, only the first high-frequency power source 152 may be connected to the mounting table 13.

In addition, in the mounting table 13, in order to control the temperature of the substrate G, a temperature control mechanism composed of a heating means such as a ceramic heater and a refrigerant flow path, a temperature sensor, and a device for transmitting heat are provided. He gas is supplied to a gas flow path (none of which is shown) on the back surface of the substrate G.

Further, for example, an exhaust port 103 is formed on the bottom surface of the container body 10, and a vacuum exhaust unit 12 including a vacuum pump or the like is connected to a downstream side of the exhaust port 103. The inside of the processing space 100 is evacuated to the pressure during the etching process by the vacuum exhaust unit 12.

As shown in FIGS. 1 and 2, a frame portion 11 that is a rectangular frame made of a metal such as aluminum is provided on the upper side of the side wall of the container body 10. A sealing member 110 is provided between the container body 10 and the frame body portion 11 to air-tightly hold the processing space 100. Here, the container body 10 and the frame body portion 11 constitute a processing container according to this embodiment.

The anode electrode portion 3 is made of a conductive material such as aluminum whose surface is anodized. The anode electrode portion 3 of this example is arranged by combining a plurality of divided electrodes 32 (32a, 32b), 33, and 34, and thereby the rectangular anode electrode portion 3 is configured as a whole.

The detailed structure of the anode electrode portion 3 of this example will be described with reference to FIG. 2. The anode electrode portion 3 is disposed inside the opening formed in the frame portion 11. An insulating member 31 is provided between the anode electrode portion 3 and the frame body portion 11, and the anode electrode portion 3 is in a state of being insulated from the frame body portion 11 or the container body 10. The anode electrode portion 3 has a rectangular planar shape corresponding to the substrate G placed on the mounting table 13. For example, the short side of the anode electrode portion 3 is formed longer than the short side of the substrate G, and the long side of the anode electrode portion 3 is formed longer than the long side of the substrate G.

The anode electrode portion 3 is arranged so that the substrate G on the mounting table 13 is aligned with the short side and the long side, and the center of the substrate G on the mounting table 13 The positions where the two diagonal lines cross) coincide with the center of the anode electrode portion 3. As a result, when the outline of the anode electrode portion 3 is projected toward the mounting table 13 side, the substrate G is in a state of being disposed inside the outline of the anode electrode portion 3.

In the above-mentioned anode electrode portion 3, when the direction from the center (central side) toward the contour side (outer peripheral side) is set to the radial direction, the anode electrode portion 3 is divided into a plurality of, for example, three in the radial direction. These divided electrodes (the inner divided electrode 34, the middle divided electrode 33, and the outer divided electrode 32) are equivalent to the radial divided electrodes of this example.

Among the radial divided electrodes divided into three, the inner divided electrode 34 provided with a sand-like hatching in FIG. For example, the inner divided electrode 34 has a rectangular planar shape.

In FIG. 2, the middle divided electrode 33 filled with gray is provided with a square ring-shaped planar shape surrounding the outer periphery of the inner divided electrode 34. Further, in the square ring-shaped region surrounding the outer periphery of the middle divided electrode 33, the outer divided electrode 32 is provided.

As shown in FIG. 2, an insulating member 31 is provided between the inner divided electrode 34 and the middle divided electrode 33 and between the inner divided electrode 33 and the outer divided electrode 32. The inner divided electrode 34 and the middle divided electrode 33 are provided. The outer peripheral divided electrodes 32 are insulated from each other.

Of the aforementioned radial divided electrodes (the inner divided electrode 34, the middle divided electrode 33, and the outer divided electrode 32), the outer divided electrode 32 located on the outermost side is further divided into, for example, eight pieces in the circumferential direction. That is, the outer peripheral divided electrode 32 is divided into four corner-divided electrodes 32b (the shaded lines given to the lower left diagonal line in FIG. 2) including the corner side of the apex of the anode electrode portion 3 are adjacent to the connection. The four side-portion-dividing electrodes 32a on the side of the vertices of the vertices (in FIG. 2, hatched lines with diagonal lines in the lower right). An insulating member 31 is provided between the adjacent corner division electrodes 32b and the side division electrodes 32a, and each corner division electrode 32b and the side division electrodes 32a are insulated from each other.

As shown in FIG. 2, the inner divided electrode 34, the middle divided electrode 33, the corner divided electrode 32 b, and the side divided electrode 32 a are each connected to the ground terminal 104. As the ground terminal 104, for example, an upper cover 50 is used. The upper cover 50 is provided on the grounded container body 10 and is electrically connected to the container body 10. As shown in FIG. 1, each of the divided electrodes 34, 33, 32b, and 32a is connected to the inner wall surface of the upper cover 50 (in FIG. 1, an example in which the corner divided electrode 32b and the side divided electrode 32a are connected) is shown. As a result, the divided electrodes 34, 33, 32b, and 32a are grounded.

With the above-mentioned configuration, the plasma processing apparatus 1 is formed with a mounting table (cathode electrode) 13 connected to the first and second high-frequency power sources 152 and 162 through the capacitive coupling plasma P and passing through the divided electrodes 34. , 33, 32b, 32a to ground 104.

The anode electrode portion 3 of this example also serves as a shower head for supplying a processing gas. As shown in FIG. 1, inside the divided electrodes (inside divided electrode 34, middle divided electrode 33, corner divided electrode 32b, and side divided electrode 32a) constituting the anode electrode portion 3, a process gas is formed to diffuse the processing gas. Process gas diffusion chamber 301. Further, a plurality of processing gas discharge holes 302 are formed under the divided electrodes 34, 33, 32b, and 32a for supplying a processing gas from the processing gas diffusion chamber 301 to the processing space 100. The process gas diffusion chamber 301 of each of the divided electrodes 34, 33, 32b, and 32a is connected to a process gas supply unit 42 (FIG. 1) via a gas supply pipe 41. The processing gas supply unit 42 supplies an etching gas that is a processing gas necessary for the etching process of the film on the substrate G.

In addition, for convenience of illustration, in FIG. 1, only a part of the split electrodes (the corner split electrodes 32 b and the side split electrodes 32 a) are illustrated as the processing gas diffusion chamber 301 or the processing gas discharge hole 302. In addition, FIG. 1 shows a state where the processing gas supply unit 42 is connected to one divided electrode (corner divided electrode 32b). Actually, all the divided electrodes (inner divided electrode 34, middle divided electrode 33, corner divided electrode 32b, and side divided electrode 32a) are provided with a processing gas diffusion chamber 301 and a processing gas discharge hole 302, and each processing gas is diffused. The chamber 301 communicates with the processing gas supply unit 42.

As shown in FIG. 1, the plasma processing apparatus 1 is provided with a control unit 6. The control unit 6 is composed of a computer including a CPU (Central Processing Unit) and a memory unit (not shown). In the memory unit, a group of steps (commands) grouped to output control signals is recorded. The program, the control signal, is used to evacuate the inside of the processing space 100 in which the substrate G is disposed, and plasma-etch the etching gas supplied between the mounting table 13 and the anode electrode portion 3 to etch the processed substrate G. action. The program is stored in a storage medium such as a hard disk, an optical disk, a magneto-optical disk, a memory card, and the like, and is installed in the memory section.

Here, a conventional plasma processing apparatus using the anode electrode portion 3a instead of the anode electrode portion 3 as described above with respect to the plasma processing device 1 of the present example having the above-mentioned configuration will be discussed. It is composed of a plurality of divided electrodes (inside divided electrode 34, middle divided electrode 33, corner divided electrode 32b, and side divided electrode 32a). The anode electrode portion 3a has the same structure as the anode electrode portion 3. One rectangular electrode with short and long sides.

Consider the following case: an anode electrode portion 3a composed of, for example, a rectangular electrode is used, the anode electrode portion 3a is connected to the ground terminal 104, and a plasma P 'is formed between the mounting table 103 and the anode electrode portion 3a. The substrate G is etched. Generally, when plasma is generated in the processing space 100 of the parallel-plate-type plasma processing apparatus 1, a region with a high plasma density tends to be concentrated in the central portion of the processing space 100.

Based on the above-mentioned characteristics, the inventors have grasped the following: In the lower side of the anode electrode portion 3a (in the processing space 100), the plasma P 'is observed at the corner side near the vertex of the anode electrode portion 3a. The density tends to be lower. As a result, when the area where the plasma P 'is formed is viewed from the upper side, as shown in the outline of the region where the density of the plasma P' is schematically shown by a dotted line in FIG. The side of the electrode portion 3 a near the short side or the long side is relatively high, and the density of the plasma P ′ is relatively low at the above-mentioned corner side.

In this way, when the region on the outer peripheral side of the anode electrode portion 3a is viewed along the circumferential direction, the substrate G is etched using a plasma P ′ having a different density in an adjacent region (corner side and side side). During the processing, there are cases in which the density distribution, the etching rate, and the like corresponding to the plasma P ′ change in the plane of the substrate G, and a uniform etching result cannot be obtained. As described above, this tendency becomes apparent when a large-sized substrate G having a length of 730 mm or more, which is a short side, is processed.

Therefore, as shown in FIG. 2, the plasma processing apparatus 1 of this example is formed between the corner division electrode 32 b and the ground end 104 and the side division electrode which constitute the outer periphery division electrode (radial direction division electrode on the outer periphery side) 32. Impedance matching adjustment sections 52 and 51 are provided between 32a and the ground terminal 104, and the impedance matching adjustment sections 52 and 51 are used to adjust from the mounting table 13 to each of the corner division electrodes 32b and the side division electrodes 32a to the ground terminal 104. Impedance of the circuit.

As shown in FIG. 1, a plurality of high-frequency power sources (a first high-frequency power source 152 and a second high-frequency power source 162) are connected to the mounting table 13 that is a cathode electrode with mutually different frequencies. Therefore, in the plasma processing apparatus 1 of this example, it is provided between the corner division electrode 32b and the ground terminal 104 and between the side division electrode 32a and the ground terminal 104, and the phase phases are provided in parallel with these plural frequencies. Corresponding plural impedance adjusting sections 52a, 52b, 51a, 51b. In addition, in FIG. 2, the impedance adjustment sections 52 a, 52 b, 51 a, and 51 b (impedance adjustment sections 52 and 51) corresponding to the respective frequencies are collectively shown.

In addition to the above-mentioned settings of the impedance adjustment sections 52 and 51, a part or all of the middle divided electrode 33 or the inner divided electrode 34 (divided into the corner divided electrode 32b and the side divided electrode 32a, other than the peripheral divided electrode 32) The radial direction dividing electrode) is provided with an impedance adjustment section 53. At this time, of course, it is also possible to provide a plurality of impedance adjustment sections 53 to the middle divided electrode 33 or the inner divided electrode 34 in correspondence with the respective frequencies of the first and second high-frequency power sources 152 and 162 connected to the mounting table 13. , 53. In addition, FIG. 2 shows an example in which an impedance adjustment unit 53 is provided between the inner divided electrode 34 and the ground terminal 104, and the middle divided electrode 33 is directly connected to the ground terminal 104.

As shown in FIG. 2, each of the impedance adjustment sections 51 to 53 includes, for example, a variable capacitor 502 and an inductor 501, and the capacity of the variable capacitor 502 can be changed to individually adjust the distance from the mounting table 13 to the ground. The impedance of the 104 circuit.

Here, the specific configuration of the impedance adjustment sections 51 to 53 is not limited to the combination of the variable capacitor 502 and the inductor 501. Examples of the case where the variable capacitor 502 is separately provided, the case where the fixed capacity capacitor and the variable capacitor 502 are combined, and the case where the variable inductor and the fixed capacitor are combined. In addition, the impedance adjustment sections 51 to 53 can change the impedance value, and are not necessary. It is also possible to configure, for example, fixed capacitors to form impedance adjusting sections 51 to 53 having preset impedance values.

The operation of the plasma processing apparatus 1 according to the present embodiment having the above-described configuration will be described below.

First, the gate valve 102 is opened, and the substrate G is carried into the processing space 100 through the carrying in / out port 101 from the adjacent vacuum carrying chamber by the carrying mechanism (the carrying mechanism and the vacuum carrying chamber are not shown). Next, the substrate G is placed on the mounting table 13 and the substrate G is fixed by an electrostatic chuck (not shown). On the other hand, the transfer mechanism is retracted from the processing space 100 and the gate valve 102 is closed.

Then, the etching gas is supplied into the processing space 100 from the processing gas supply unit 42 through the processing gas diffusion chamber 301, and the inside of the processing space 100 is evacuated by the vacuum evacuation unit 12. It is adjusted to a pressure atmosphere of, for example, about 0.66 to 26.6 Pa. In addition, He gas for heat conduction is supplied to the substrate G from a gas flow path (not shown).

Next, when high-frequency power is applied from the first high-frequency power source 152 to the anode electrode portion 3, the capacitive coupling between the mounting table 13 and the anode electrode portion 3 causes the etching gas to be plasmatized in the processing space 100. Thereby, a high-density plasma P is generated. Then, by the high-frequency power for the bias voltage applied to the mounting table 13 from the second high-frequency power source 162, ions in the plasma are introduced toward the substrate G to perform an etching process on the substrate G.

At this time, as compared with the conventional example using the anode electrode portion 3a described in FIG. 3, in the plasma processing apparatus 1 of this example, the peripheral divided electrode 32 located on the outer peripheral side is divided into corner portions toward the circumferential direction. The electrode 32b and the side-divided electrode 32a are provided with impedance adjustment sections 52 and 51 respectively at the divided electrodes 32b and 32a.

Therefore, the impedance values of the impedance adjustment sections 52 and 51 are adjusted so that the density of the plasma P is the same as that of the area below the corner division electrode 32b with respect to the area below the side division electrode 32a. Specifically, the high-density region of the plasma P is diffused to the corner portion side of the anode electrode portion 3. As a result, compared with the etching process using the plasma P ′ generated by the conventional anode electrode portion 3 described in FIG. 3, the plasma P at the corner portion and the side portion of the anode electrode portion 3 can be reduced. The density difference is high, and the etching treatment with high in-plane uniformity is performed.

As a technique for increasing the density of the plasma P ′ in the corner side of the anode electrode portion 3 as compared with the conventional technique, as shown in the experimental results of the reference example described later, the following technique can be exemplified: The impedance adjustment sections 52 and 51 of the corner division electrode 32b or the side division electrode 32a are in a circuit from the mounting table 13 through the corner division electrode 32b to the ground terminal 104, compared with the same circuit on the side of the side division electrode 32a. The impedance adjustment is performed so that the DC component of the high-frequency voltage on the mounting table 13 side becomes the same or larger.

In addition, there is also a case where the plasma density is concentrated in the region below the inner divided electrode 34 due to the characteristics of the plasma P concentrated on, for example, the central portion side of the anode electrode portion 3, as compared with its outer periphery. The area on the side (below the middle divided electrode 33 or the outer divided electrode 32) tends to be high and the etching rate tends to increase.

In this case, the density of the plasma P in the region below the inner divided electrode 34 is reduced to be the same as the density of the plasma P in the outer peripheral side, thereby reducing the density difference of the plasma P between these regions. In addition, an etching process with high in-plane uniformity is performed. As a method for reducing the density of the plasma P in the area below the inner divided electrode 34, as shown in the experimental results of the reference example described later, the following method can be exemplified: when using the impedance connected to the inner divided electrode 34, The adjustment unit 53 adjusts the impedance of the circuit from the mounting table 13 through the inner divided electrode 34 to the ground terminal 104 so that the DC component of the high-frequency voltage on the mounting table 13 side becomes small.

In addition, the effects of impedance adjustment by using the impedance adjustment sections 51 to 53 are listed. As shown in the experimental results described below, the inventors have grasped the following: When the current flowing through each of the inner divided electrode 34, the middle divided electrode 33, and the outer divided electrode 32 of the anode electrode portion 3 becomes large, The surface thickness of each of the divided electrodes 34, 33, and 32 is reduced by the reduction of the plasma P (hereinafter, referred to as "consumption"), and tends to become larger. Therefore, as described above, after adjusting the impedance values of the impedance adjustment sections 51 to 53 so that the density of the plasma P is uniform on the surface of the anode electrode section 3, the in-plane uniformity does not affect the etching process. Within the range, the fine adjustment of the impedance values of the impedance adjusting sections 51 to 53 is performed so that the current flowing through each circuit from the mounting table 13 to the ground terminal 104 is reduced as much as possible, thereby reducing each division. Consumption of electrodes 34, 33, 32.

Using the anode electrode section 3 with the impedance adjustment described above, after the plasma P is generated in the processing space 100 and the etching process is performed for only a predetermined time, the power supply from the high-frequency power sources 152 and 162 and the process gas supply are stopped. The etching gas supply of the portion 42 and the vacuum evacuation in the processing space 100 are carried out in a reverse order from the time of carrying in the substrate G.

The plasma processing apparatus 1 according to this embodiment has the following effects. In the parallel-plate-type plasma processing apparatus 1 that performs the etching process of the rectangular substrate G, the peripheral divided electrode 32 is disposed so as to face the substrate G and is located on the outer peripheral side of the anode electrode portion 3 in a rectangular planar shape. It is divided into a corner division electrode 32b on the corner side and a side division electrode 32a on the side side. Furthermore, impedance adjusting sections 51 to 53 are provided, and the impedance adjusting sections 51 to 53 are used to adjust the impedance of the circuit from the mounting table (cathode electrode) 13 to the ground terminal 104 through the plasma P. As a result, the substrate G at a position corresponding to the corner portion and the side portion can be uniformly plasma-treated.

Obtaining the above-mentioned effects is not limited to the case where the plasma processing apparatus 1 is configured as an etching apparatus that performs an etching process. In the case where the plasma processing apparatus 1 is configured as a film-forming apparatus that performs a film-forming process on the substrate G or an ashing apparatus that performs an ashing process on the photoresist film, a uniform treatment can be performed on the surface of the substrate G as well.

Here, the anode electrode portion 3 only needs to be divided into at least two in the radial direction. In addition, the “radial-direction divided electrode located on the outer peripheral side” means that the electrode is disposed from the center of the anode electrode portion 3 to the outside of the anode electrode portion 3 among a plurality of radial-direction divided electrodes that are divided in the radial direction. If the distance of the edge (the short side or the long side mentioned above) is 1/2 to the outer area, the impedance can be adjusted by dividing the corner divided electrode 32b and the side divided electrode 32a to make use of the foregoing. Effect.

Here, as shown in the description using FIG. 2, the anode electrode portion 3 of this example is impedance adjustment common to the four corner division electrodes 32 b on the corner side, which are connected to the outer periphery division electrodes 32 on the outermost side. The portion 52 is connected to the impedance adjustment portion 51 which is common to the four corner division electrodes 32 a located on the side portion side. On the other hand, it is not necessary to share the impedance adjustment unit 52 with respect to the four corner division electrodes 32b, and to share the impedance adjustment unit 51 with respect to the four corner division electrodes 32a. The diagonal division electrodes 32b and the respective lateral division electrodes 32a are provided with impedance adjustment sections 52 and 51, respectively.

In addition, it is not necessary to connect both the corner division electrode 32b and the side division electrode 32a to the impedance adjustment portions 52 and 51. As long as at least one of the corner-divided electrode 32b or the side-divided electrode 32a is connected to the impedance adjustment sections 52 and 51 to perform impedance adjustment, the density of the plasma P at the corner and side of the anode electrode section 3 can be reduced Poor, and obtain the effect of improving the uniformity in the plasma treated surface.

In addition, the radial-direction divided electrode that is divided in the circumferential direction is not limited to the outer-peripheral divided electrode 32 arranged on the outermost peripheral side. Among the radial-direction divided electrodes (the inner divided electrode 34, the middle divided electrode 33, and the outer divided electrode 32), the middle divided electrode 33 may be divided in the circumferential direction. As shown in the anode electrode portion 3b shown in FIG. 4, when the middle divided electrode 33 is divided into a corner divided electrode 33b and a side divided electrode 33a, the corner divided electrode 33b is disposed at a corner that may affect the anode electrode portion 3. In the case of a region having a density of the plasma P on the part side, at least one of the corner division electrodes 33b and the side division electrodes 33a is connected to the impedance adjustment units 52 and 51 to perform the aforementioned impedance adjustment. It can help improve the in-plane uniformity of plasma treatment.

In addition, the number of electrodes divided in the radial direction divided in the circumferential direction is not limited to one. As shown in the anode electrode portion 3c shown in FIG. 5, in addition to dividing the peripheral divided electrode 32 into a corner divided electrode 32b and a side divided electrode 32a toward the circumferential direction, the intermediate divided electrode 33 may be divided into corner portions toward the circumferential direction. The division electrode 33b and the side division electrode 33a. In this case, it is preferable that the corner division electrode 33b of the middle division electrode 33 is connected to an impedance adjustment portion different from the corner division electrode 32b of the outer division electrode 32, and the side division electrode of the middle division electrode 33 is also preferable. 33a is preferably an impedance adjusting portion connected to the edge division electrode 32a different from the peripheral division electrode 32.

In addition, for example, in the anode electrode portion 3c shown in FIG. 5, (i) a case where the corner division electrode 33b and the side division electrode 33a of the middle division electrode 33 are connected to a common impedance adjustment portion, (ii) Each of the corner division electrodes 33b and the side division electrodes 33a is connected to an individual impedance adjustment unit. In a circuit from the mounting table 13 to each of the division electrodes 33b and 33a through the capacitive coupling plasma P to the ground terminal 104, for example, electricity In the case where the impedance is adjusted so that the impedances per unit area of the divided electrodes 33b and 33a are consistent when viewed from the side of the slurry P, (iii) the impedance adjustment section is directly connected to the ground terminal 104 and not to the corner of the middle divided electrode 33 In the case of the partial division electrode 33b and the side division electrode 33a. In these cases, the state of the plasma P formed on the lower side of each divided electrode 33b, 33a has not changed since the state of the plasma P formed on the lower side of the undivided middle divided electrode 33. .

Therefore, in the cases of (i) to (iii), even if the middle split electrode 33 is structurally divided into a plurality of split electrodes 33b, 33a, it can be said that the capacitive coupling plasma P is formed, and it is not used in conjunction with The case of the integrally-divided middle split electrode 33 is different. For example, the middle divided electrode 33 and the inner divided electrode 34 shown in FIG. 2 also include those that are divided into any one of (i) to (iii).

Furthermore, the shape of the radial direction divided electrode obtained by dividing the anode electrode portion 3 into a plurality of radial directions is not limited to the rectangular shape (inside divided electrode 34) and the square ring shape (intermediate divided electrode 33) shown in FIG. In the case of the peripheral divided electrode 32). For example, the inner divided electrode 34 may be formed in an oval shape, and the middle divided electrode 33 may be formed in an oval ring shape surrounding the outer periphery of the inner divided electrode 34. In this case, the outer peripheral divided electrode 32 has a shape in which the remaining areas of the inner divided electrode 34 and the middle divided electrode 33 on the ellipse are removed from the rectangular anode electrode portion 3. Therefore, the shapes of the corner divided electrodes 32b and the side divided electrodes 32a obtained by dividing the outer divided electrodes 32 and the like in the circumferential direction are not limited to the example shown in FIG. 2. Of course, the shapes of the outer divided electrodes 32 may be changed according to the shape of the outer divided electrodes 32 and the like. Decide appropriately.

    [Example]         (Experiment 1)    

Regarding the anode electrode portion 3d provided with the three radial-direction divided electrodes (the inner divided electrode 34, the middle divided electrode 33, and the outer divided electrode 32) shown in FIG. 6, the impedance adjustment using the impedance adjustment units 53, 54 is performed on one side. Measurements of current values and the like were performed. In addition, in the anode electrode portion 3d shown in FIG. 6, the description that the outer peripheral divided electrode 32 is connected to the ground terminal 104 is omitted.

    A. Experimental conditions    

(Reference Example 1-1) Using the plasma processing apparatus 1 provided with the anode electrode portion 3d shown in FIG. 6, impedance was provided between the inner divided electrode 34 and the ground terminal 104 and between the middle divided electrode 33 and the ground terminal 104. The adjustment units 53 and 54 change the capacitance of the variable capacitor 502 provided in the impedance adjustment unit 53 on the inner divided electrode 34 side, and measure the current flowing through each circuit with the ammeters 503 and 504. During this operation period, the capacitance of the variable capacitor 502 on the side of the middle split electrode 33 is fixed. In addition, a change in voltage on the mounting table 13 (cathode electrode) side was measured by a voltmeter (not shown) of the matching device 151 provided on the first high-frequency power source 152 side. A mixed gas of CF ₄ and O ₂ was supplied from the processing gas supply unit 42 at 1000 sccm (standard state: 25 ° C., 1 atmosphere standard), and the pressure of the processing space 100 was adjusted to 1.33 Pa (10 mTorr). Further, 22 kW of high-frequency power is supplied from the first high-frequency power source 152 and the second high-frequency power source 162, respectively.

(Reference Example 1-2) Under the same conditions as in Reference Example 1-1, the capacitance of the variable capacitor 502 provided in the impedance adjustment section 54 provided on the side of the middle split electrode 33 was changed, and the current flowing through each circuit was measured. Current and voltage on the mounting table 13 side. During this operation period, the capacitance of the variable capacitor 502 on the inner divided electrode 34 side is fixed.

    B. Experimental results    

The results of Reference Example 1-1 are shown in FIG. 7, and the results of Reference Example 1-2 are shown in FIG. 8. The horizontal axis of FIGS. 7 and 8 indicates the dial value of the variable capacitor 502. The smaller the transfer value is, the larger the capacitance of the variable capacitor 502 is, and the larger the transfer value is, the smaller the capacitance becomes. The vertical axis on the left side of FIGS. 7 and 8 indicates the current value of each of the divided electrodes 34 and 33, and the vertical axis on the right side indicates the current value on the mounting table 13 side. In each drawing, the change in the current value on the inner divided electrode 34 side is shown by a one-dot chain line, and the change in the current value on the middle divided electrode 33 side is shown by a solid line. The change in the voltage value on the mounting table 13 side is indicated by a dotted line.

According to the result of Reference Example 1-1 shown in FIG. 7, when the transfer value of the variable capacitor 502 provided in the impedance adjustment section 53 is gradually increased (the capacitance of the variable capacitor 502 is gradually decreased), After the current value on the inner divided electrode 34 side increases and the transfer value is in the range of 3.5 to 4.5, the current value on the inner divided electrode 34 side decreases gradually as the transfer value is further increased.

On the other hand, during the above-mentioned dial operation, the current value on the side of the middle split electrode 33 is maintained at a relatively low state and hardly changed.

Moreover, during the above-mentioned dialing operation, a phenomenon in which the voltage value on the mounting table 13 side decreased in accordance with the increase or decrease in the current value on the inner divided electrode 34 side was observed. Therefore, the change in the value of the current flowing through the inner divided electrode 34 can be estimated to occur because high-frequency power supplied from the mounting table 13 side is introduced to the inner divided electrode 34 side via the plasma source P.

On the other hand, among the results of the reference example 1-2 shown in FIG. 8, the results are comparable to the experimental results of the reference example 1-1 shown in FIG. 7.

That is, when the transfer value of the variable capacitor 502 provided in the impedance adjustment section 54 is gradually increased, the current value on the side of the middle split electrode 33 increases and the transfer value is in the range of 2 to 4 indicating a peak value. Later, as the transfer value is further increased, the current value on the side of the middle split electrode 33 gradually decreases.

On the other hand, during the above-mentioned dialing operation period, the current value on the side of the inner divided electrode 34 is maintained at a relatively low state with almost no change.

In addition, during the above-mentioned dialing operation, a phenomenon in which the voltage value on the mounting table 13 side decreased in accordance with the increase or decrease in the value of the current flowing through the middle division electrode 33 was observed. Therefore, it can be estimated that the change in the current on the side of the middle divided electrode 33 is caused by the high-frequency power supplied from the mounting table 13 side being introduced to the side of the middle divided electrode 33 via the plasma source P.

From the above experimental results, it can be confirmed that by adjusting the impedance values of the impedance adjustment units 53 and 54 provided in the middle division electrode 33 and the inner division electrode 34, the middle division electrode 33 and the inner division electrode 34 can be adjusted. The adjustment for increasing or decreasing the current flowing through the circuit including the divided electrodes 33 and 34 (the circuit from the mounting table 13 to the ground terminal 104) is performed independently of each other.

This result is similarly true when the impedance values of the impedance adjustment sections 52 and 51 are adjusted between the corner division electrodes 32 b and the side division electrodes 32 a shown in FIG. 2.

(Experiment 2) A substrate G was etched using a plasma processing apparatus 1 provided with an anode electrode portion 3d shown in FIG. 6.

    A. Experimental conditions    

(Reference Example 2-1) At a position where the DC component (Vdc) of the voltage value measured on the mounting table 13 side is minimized, the transfer value of the variable capacitor 502 in each of the impedance adjustment sections 53 and 54 is set, and the The etching process of the substrate G was performed under the same conditions as in Reference Example 1-1. The adjustment value of the variable capacitor 502 in the impedance adjustment unit 53 on the inner divided electrode 34 side is 4.5, and is a position corresponding to the peak value of the current value on the inner divided electrode 34 side in FIG. 7. The transfer value of the variable capacitor 502 on the middle split electrode 33 side is 3.0, and is a position corresponding to the peak value of the current value on the middle split electrode 33 side in FIG. 8.

(Reference Example 2-2) At a position where the direct current component (Vdc) of the voltage value measured on the mounting table 13 side becomes the largest, the transfer value of the variable capacitor 502 in each impedance adjustment section 53 and 54 is set, and the The etching process of the substrate G was performed under the same conditions as in Reference Example 1-1. The adjustment value of the variable capacitor 502 in the impedance adjustment unit 53 on the inner divided electrode 34 side is 8.0, and is a position where the current value on the inner divided electrode 34 side in FIG. 7 becomes the smallest. The transfer value of the variable capacitor 502 on the middle split electrode 33 side is 8.0, and is the position where the current value on the middle split electrode 33 side in FIG. 8 becomes the smallest.

(Comparative Example 2) The substrate G is etched without providing the impedance adjustment sections 53 and 54 between the inner divided electrode 34 and the ground terminal 104 and between the middle divided electrode 33 and the ground terminal 104.

    B. Experimental results    

The results of Reference Examples 2-1, 2-2, and Comparative Example 2 are shown in FIG. 9. The horizontal axis in FIG. 9 indicates the DC component of the voltage value measured on the mounting table 13 side. In addition, the vertical axis on the left side of FIG. 9 indicates the etching rate per unit time, and the vertical axis on the right side indicates the uniformity of the etching rate in the plane of the substrate G (((standard deviation σ) / (average Ave)). } × 100 [%]).

In FIG. 9, the outline of the hollow circle represents the average value of the etching rate of the substrate G in the area below the inner divided electrode 34, and the outline of the black circle represents the lower side of the middle divided electrode 33 The average value of the etching rate of the substrate G in the region. In addition, the tracing points of the hollow crossbars indicate the maximum value of the etching rate in the area below the peripheral divided electrode 32, and the tracing points of the black crossbars indicate the etching in the lower area of the peripheral divided electrode 32. The minimum speed. In addition, the black-spotted diamond-shaped dots represent the average value of the etching rate in the plane of the substrate G, and the X-marked dots represent the uniformity of the etching rate.

According to the results of Reference Examples 2-1 and 2-2 shown in FIG. 9, when the DC component of the voltage value on the mounting table 13 side is the smallest, the average etching rate in each region and the G plane of the substrate becomes smaller ( Reference Example 2-1) When the above-mentioned direct current component is the largest, the average etching rate in each region and the G plane of the substrate is increased. Therefore, it was confirmed that the adjustment of the impedance value using the impedance adjustment sections 53 and 54 can change the etching rate of the substrate G.

This result can also be said to be the same when the impedance values of the impedance adjustment sections 52 and 51 are adjusted between the corner division electrodes 32 b and the side division electrodes 32 a shown in FIG. 2.

On the other hand, in Comparative Example 2 in which the impedance adjustment sections 53 and 54 are not provided on the ground division 104 side of the inner divided electrode 34 and the middle divided electrode 33, an upwardly convex etching rate distribution is formed, and the inner divided electrode is formed on the inner divided electrode. 34 or the area below the middle divided electrode 33 has a higher etching rate, and the area under the peripheral divided electrode 32 has a lower etching rate. As a result, compared with Reference Examples 2-1 and 2-2, the value of the uniformity of the etching rate was worse. Furthermore, in Comparative Example 2, there is no means for changing the etching rate by adjusting the impedance of the circuit from the mounting table 13 to the ground point.

(Experiment 3) Using the plasma processing apparatus 1 provided with the anode electrode part 3d shown in FIG. 6, the consumption amount of the anode electrode part 3d was measured.

    A. Experimental conditions    

(Reference Example 3-1) A test piece composed of an aluminum wafer was attached to the lower surface of the inner divided electrode 34, and the same operation as in Reference Example 1-1 was performed, and the current value flowing through the circuit on the inner divided electrode 34 side was made. While changing, the plasma P was generated only for a predetermined time, and the consumption of the test piece was measured.

(Reference Example 3-2) The aforementioned test piece to which the middle divided electrode 33 was attached was subjected to the same operation as that of Reference Example 1-2, and the same experiment as that of Reference Example 3-1 was performed.

    B. Experimental results    

The results of Examples 3-1 and 3-2 are shown in Figs. 10 and 11 respectively. In these figures, the horizontal axis represents the current value flowing through each of the divided electrodes 34 and 33, and the vertical axis represents the sputtering amount of the test piece. The amount of sputtering in each current value is indicated by the black-drawn diamond-shaped trace points. In each figure, the amount of sputtering of the test piece in the case where the impedance adjustment sections 53 and 54 are not provided is shown by a dotted line.

According to the results of Reference Examples 3-1 and 3-2 shown in FIG. 10 and FIG. 11, even in any of the inner divided electrode 34 and the middle divided electrode 33, the currents flowing through the divided electrodes 34 and 33 also follow. The larger the amount of sputtering of the test piece becomes. Therefore, in a range where a desired etching rate can be obtained in the substrate G arranged in a region below each of the divided electrodes 34 and 33, the current flowing through the divided electrodes 34 and 33 can be reduced. By adjusting the impedance values of the impedance adjustment sections 53 and 54, the consumption of the inner divided electrode 34 and the middle divided electrode 33 can be reduced.

This result can be said to be the same even in the corner division electrode 32 b and the side division electrode 32 a shown in FIG. 2.

Claims (6)

    The utility model relates to a plasma processing device, which performs plasma processing on a rectangular substrate to be processed in a vacuum-exhausted processing container. The plasma processing device is characterized in that: : The cathode electrode is placed in the aforementioned processing container in an insulated state from the processing container, and is connected to a high-frequency power supply via a matching circuit, and a rectangular substrate to be processed is placed thereon; and an anode electrode section is connected with The method of facing the cathode electrode is arranged in an insulated state from the processing container and has a rectangular planar shape corresponding to the substrate to be processed. The anode electrode portion is located at the center from the anode electrode portion. When the direction from the side toward the outer peripheral side is set as the radial direction, the radial direction is divided into a plurality of radial direction split electrodes. The radial direction split electrodes are respectively connected to the ground terminal in a state of being insulated from each other. Among the plurality of radial-direction divided electrodes, the radial-direction divided electrodes located on the outer peripheral side are divided toward the circumferential direction and are divided into corner portions located on the anode electrode portion. The plurality of corner-dividing electrodes and the plurality of side-dividing electrodes located on the side of the corner are respectively connected to the ground terminal in a state of being insulated from each other. At least one of the corner-dividing electrode and the side-dividing electrode is provided with an impedance adjusting portion for adjusting the ground electrode from the cathode electrode to each corner-dividing electrode or the edge-dividing through the plasma through the impedance adjustment portion. The impedance of the circuit at the electrode's ground.         For example, the plasma processing apparatus in the first scope of the patent application, wherein the radial-direction divided electrode that is divided into the aforementioned corner-divided electrode and the edge-divided electrode is located on the outermost peripheral side of the plurality of radial-direction divided electrodes.         For example, the plasma processing apparatus according to item 1 or 2 of the patent application scope, wherein the impedance adjustment unit provided at least one of the corner division electrode and the side division electrode is relative to the plurality of corner division electrodes or the aforementioned division. A plurality of edge division electrodes are common.         For example, the plasma processing device of the first or second scope of the patent application, wherein the impedance adjustment unit is provided for at least one of the radial direction division electrodes divided into the corner division electrodes and the side division electrodes, and the impedance adjustment is provided. The part is used to adjust the impedance of the circuit from the cathode electrode to the ground terminal of the divided electrode in each radial direction through the plasma.         For example, the plasma processing device of the first or second scope of the patent application, wherein the cathode electrode is connected to a plurality of high-frequency power sources with mutually different frequencies, and on the ground end side of the division electrode provided with the impedance adjustment section, A plurality of impedance adjusting sections corresponding to the respective frequencies of the plurality of high-frequency power sources are provided in parallel.         For example, the plasma processing apparatus according to item 1 or 2 of the patent application range, wherein the impedance adjustment unit is configured to change an impedance value.