JP6769127B2 - Plasma processing equipment - Google Patents

Description

The present invention relates to a plasma processing apparatus that performs plasma processing of a substrate to be processed with a plasma-generated processing gas.

In the manufacturing process of a flat panel display (FPD) such as a liquid crystal display (LCD), a plasma-generated processing gas is supplied to a glass substrate which is a rectangular substrate to be processed, and plasma processing such as etching processing and film formation processing is performed. There is a step to do. Various plasma processing devices such as a plasma etching device and a plasma CVD device are used for these plasma treatments.
Further, in the plasma processing of the rectangular substrate to be processed, the processing is made into plasma toward the outer peripheral region including the corners around the vertices of the substrate to be processed and the side portions between these corners. It is required to supply the gas uniformly.

Here, in Patent Document 1, a capacitive coupling is formed in which an upper electrode and a lower electrode are opposed to each other, a substrate to be processed is placed on the lower electrode, and high frequency power is applied to one side of the upper and lower electrodes. A parallel plate type plasma processing apparatus for converting the processing gas into plasma is described.
The plasma processing apparatus described in Patent Document 1 is provided with a plurality of impedance adjusting portions at portions laterally separated from each other on the upper surface side of the upper electrode configured as the anode electrode to adjust the impedance, thereby forming the anode electrode. It is possible to suppress the generation of unnecessary plasma due to capacitively coupling with the wall of the processing container.

Further, Patent Document 2 describes that in a parallel plate type plasma processing apparatus that performs plasma processing, it is connected to an RF power source and faces a mounting electrode (corresponding to a cathode electrode) on which a semiconductor wafer to be processed is mounted. In addition to arranging the counter electrode (corresponding to the anode electrode), the counter electrode is divided into zones having different distances from the center, and the impedance is made different between these zones. The technology provided with is described.
However, both of these Patent Documents 1 and 2 disclose a technique for uniformly supplying plasma-generated processing gas to the corners and sides when performing plasma treatment on a rectangular substrate to be processed. It has not been.

Japanese Patent No. 4553247: Claims 1 and 2, paragraphs 0034, 0041, FIG. JP-A-6-61185: Claims 1 and 2, paragraphs 0030 to 0031, FIGS. 1 and 2.

The present invention has been made under such circumstances, and an object of the present invention is to provide a technique for performing more uniform plasma processing in the circumferential direction with respect to a region on the outer peripheral side of a rectangular substrate to be processed. There is.

The plasma processing apparatus of the present invention is a plasma processing apparatus that executes plasma processing with a plasma-generated processing gas on a rectangular substrate to be processed in a vacuum-exhausted processing container.
A cathode electrode, which is arranged in the processing container in a state of being insulated from the processing container, connected to a high-frequency power supply via a matching circuit, and on which a rectangular substrate to be processed is placed.
It is provided with an anode electrode portion which is arranged in a state of being insulated from the processing container so as to face the cathode electrode and has a rectangular planar shape corresponding to the substrate to be processed.
The anode electrode portion is
When the direction from the center side to the outer peripheral side of the anode electrode portion is the radial direction, the anode electrode portion is divided into a plurality of radial division electrodes toward the radial direction, and the radial division electrodes are each insulated from each other. It is connected to the grounding end with
Among the plurality of radial split electrodes, the radial split electrodes located on the outer peripheral side are located on the corner side of the anode electrode portion in the circumferential direction, and are arranged adjacent to each other on the central side. A plurality of corner-divided electrodes having a side extending along the shape of the other radial-divided electrode, and a plurality of corner-divided electrodes located on the side of the other radial-divided electrode, respectively. is divided into a plurality of side portions divided electrodes which have a side extending along a shape, these corner portions divided electrode and the side portions divided electrodes are each a that is connected to the ground terminal in a state of being insulated from each other,
The impedance of the circuit from the cathode electrode to the grounded end of each corner divided electrode or the side divided electrode via plasma is adjusted on at least one grounded end side of the corner divided electrode and the side divided electrode. It is characterized in that an impedance adjusting unit is provided for this purpose.

The present invention is a parallel plate type plasma processing apparatus that performs plasma processing on a rectangular substrate to be processed, and has a planar shape arranged so as to face the substrate to be processed and having a diameter located on the outer peripheral side of the rectangular anode electrode portion. The direction-dividing electrode is divided into a plurality of corner-divided electrodes located on the corner side and a plurality of side-divided electrodes located on the side, and the circuit from the cathode electrode to the grounding end via plasma. An impedance adjustment unit for adjusting the impedance is provided. As a result, uniform plasma treatment can be performed on the substrate to be processed at positions corresponding to the corners and sides.

It is a longitudinal side view of the plasma processing apparatus which concerns on embodiment. It is a top view of the anode electrode part provided in the plasma processing apparatus. It is an operation diagram of the conventional plasma processing apparatus. It is a top view which shows the 1st modification of the anode electrode part. It is a top view which shows the 2nd modification of the anode electrode part. It is a top view of the anode electrode part used in an experiment. It is explanatory drawing which shows the impedance adjustment result on the inner split electrode side. It is explanatory drawing which shows the impedance adjustment result on the intermediate division electrode side. It is explanatory drawing which shows the result of the etching process using a split electrode. It is explanatory drawing which shows the relationship between the electric current flowing through the inner dividing electrode, and the consumption amount of a test piece. It is explanatory drawing which shows the relationship between the electric current flowing through the intermediate division electrode, and the consumption amount of a test piece.

The plasma processing apparatus 1 of this example is a rectangular substrate to be processed, for example, a metal film, an ITO (Tin-doped Indium Oxide) film, an oxide film, etc. for forming a thin film transistor on a substrate G for FPD. It can be used for various plasma treatments such as a film forming treatment for forming, an etching treatment for etching these films, and an ashing treatment for a resist film. Here, examples of the FPD include a liquid crystal display (LCD), an electro Luminescence (EL) display, and a plasma display panel (PDP). Further, the plasma processing device 1 can be used not only for the substrate G for the FPD but also for the various plasma treatments described above for the substrate G for the solar cell panel.

Hereinafter, with reference to FIGS. 1 and 2, etching of a film formed on a large glass substrate (hereinafter simply referred to as a substrate) G having a short side length of 730 mm or more and a long side length of 920 mm or more. A plasma processing apparatus 1 configured as an etching apparatus for performing processing will be described. As shown in FIG. 1, the plasma processing apparatus 1 includes a square cylinder-shaped container body 10 made of a conductive material, for example, aluminum whose inner wall surface is anodized, and the container body 10 is electrically grounded. ing. An opening is formed in the upper surface of the container body 10 (frame body portion 11 described later), and this opening is airtightly closed by the anode electrode portion 3. The space surrounded by the container body 10 and the anode electrode portion 3 becomes the processing space 100 of the substrate G, and the upper side of the anode electrode portion 3 is made of a conductive material in which the impedance adjusting portions 51, 52 and the like described later are arranged. It is covered by the top cover 50. Further, on the side wall of the processing space 100, a carry-in outlet 101 for loading and unloading the substrate G and a gate valve 102 for opening and closing the carry-in outlet 101 are provided.

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 portion 3 in the vertical direction. The mounting table 13 is made of a conductive material, for example, aluminum whose surface has been anodized. The substrate G mounted on the mounting table 13 is attracted and held by an electrostatic chuck (not shown). The mounting table 13 is housed in the insulator frame 14, and is installed on the bottom surface of the container body 10 via the insulator frame 14.

The first and second high-frequency power supplies 152 and 162 are connected to the mounting table 13 via the matching units 151 and 161 respectively.
From the first high frequency power supply 152, high frequency power having a frequency in the range of, for example, 10 to 30 MHz is supplied. The electric power supplied from the first high-frequency power source 152 plays a role of forming a high-density capacitively coupled plasma P between the mounting table 13 and the anode electrode portion 3.

On the other hand, from the second high frequency power supply 162, high frequency power for bias, for example, high frequency power having a frequency in the range of 2 to 6 MHz is applied. The self-bias generated by the high-frequency power for bias allows the ions in the plasma P generated in the processing space 100 to be drawn into the substrate G.

The mounting table 13 to which high-frequency power is supplied from the first and second high-frequency power supplies 152 and 162 in order to form the plasma P with the anode electrode portion 3 corresponds to the cathode electrode of the present embodiment. It is not an essential requirement to connect a plurality of high frequency power supplies (first high frequency power supply 152, second high frequency power supply 162) having different frequencies to the mounting table 13. For example, only the first high frequency power supply 152 may be connected to the mounting table 13.
Further, in the mounting table 13, in order to control the temperature of the substrate G, a temperature control mechanism including a heating means such as a ceramic heater and a refrigerant flow path, a temperature sensor, and a He gas for heat transfer on the back surface of the substrate G Is provided with a gas flow path for supplying (neither is shown).

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 the downstream side of the exhaust port 103. The inside of the processing space 100 is evacuated to the pressure at the time of etching processing by the vacuum exhaust unit 12.

As shown in FIGS. 1 and 2, a frame body portion 11 which is a rectangular frame body made of a metal such as aluminum is provided on the upper surface side of the side wall of the container body 10. A seal member 110 for keeping the processing space 100 airtight is provided between the container body 10 and the frame body portion 11. Here, the container body 10 and the frame body portion 11 constitute the processing container of the present embodiment.

The anode electrode portion 3 is made of a conductive material, for example, aluminum whose surface has been anodized. Further, the anode electrode portion 3 of this example constitutes a rectangular anode electrode portion 3 as a whole by arranging a plurality of divided electrodes 32 (32a, 32b), 33, 34 in combination.

Explaining the detailed configuration of the anode electrode portion 3 of this example with reference to FIG. 2, the anode electrode portion 3 is arranged inside the opening formed in the frame body 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 and the container body 10. The anode electrode portion 3 has a rectangular planar shape corresponding to the substrate G mounted 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.

Further, the anode electrode portion 3 has the directions of the short side and the long side aligned with the substrate G on the mounting table 13, and the center of the substrate G on the mounting table 13 (two diagonal lines connecting the opposing vertices of the rectangles). (Position where) and the center of the anode electrode portion 3 are aligned. As a result, when the contour of the anode electrode portion 3 is projected toward the mounting table 13, the substrate G is in a state of being arranged inside the contour of the anode electrode portion 3.

When the direction from the center (center side) to the contour side (outer peripheral side) of the above-mentioned anode electrode portion 3 is the radial direction, the anode electrode portion 3 is divided into a plurality, for example, three in the radial direction. ing. These divided electrodes (inner divided electrode 34, intermediate divided electrode 33, outer peripheral divided electrode 32) correspond to the radial divided electrode of this example.
Of the three radial split electrodes, the inner split electrode 34 having sand-like hatching in FIG. 2 is arranged on the central side of the anode electrode portion 3. For example, the inner split electrode 34 has a rectangular planar shape.

In FIG. 2, the intermediate split electrode 33 painted in gray has a planar annular shape surrounding the outer periphery of the inner split electrode 34. Further, the outer peripheral dividing electrode 32 is provided in the angular annular region surrounding the outer periphery of the intermediate dividing electrode 33.
As shown in FIG. 2, an insulating member 31 is provided between the inner split electrode 34 and the intermediate split electrode 33, and between the intermediate split electrode 33 and the outer peripheral split electrode 32, and the inner split electrode 34 and the intermediate split electrode are provided. 33, the outer peripheral dividing electrode 32 is insulated from each other.

Of the above-mentioned radial dividing electrodes (inner dividing electrode 34, intermediate dividing electrode 33, outer peripheral dividing electrode 32), the outer peripheral dividing electrode 32 located on the outermost side is further divided into, for example, eight in the circumferential direction. There is. That is, the outer peripheral split electrode 32 is located between the four corner split electrodes 32b on the corner side including the vertices of the anode electrode portion 3 (hatched with diagonal lines downward to the left in FIG. 2) and the adjacent vertices. It is divided into four side division electrodes 32a (in FIG. 2, hatched with diagonal lines downward to the right) located on the side to be connected. An insulating member 31 is provided between the adjacent corner dividing electrodes 32b and the side dividing electrodes 32a, and the corner dividing electrodes 32b and the side dividing electrodes 32a are insulated from each other.
Here, as shown in FIG. 2, each corner split electrode 32b is a corner side of the anode electrode portion 3 in the intermediate split electrode 33 which is another radial split electrode arranged adjacent to the center side. It has an L-shaped side extending along the shape of. Further, as also shown in FIG. 2, each side split electrode 32a has a linear shape extending along the side shape of the anode electrode portion 3 in the intermediate split electrode 33 arranged adjacent to the center side. It has an edge.

As shown in FIG. 2, the inner split electrode 34, the intermediate split electrode 33, the corner split electrode 32b, and the side split electrode 32a are each connected to the ground end 104. For example, as the grounding end 104, an upper cover 50 provided on the upper surface of the grounded container body 10 and electrically conducting with the container body 10 is used. As shown in FIG. 1, the divided electrodes 34, 33, 32b, and 32a are connected to the inner wall surface of the upper cover 50 (in FIG. 1, an example in which the corner divided electrodes 32b and the side divided electrodes 32a are connected). By (shown), these dividing electrodes 34, 33, 32b, 32a are grounded.

With the above configuration, the plasma processing apparatus 1 is provided with the divided electrodes 34, 33 from the mounting table (cathode electrode) 13 connected to the first and second high frequency power supplies 152 and 162 via the capacitively coupled plasma P. A circuit is formed that passes through 32b and 32a and reaches the grounding end 104.

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

For convenience of illustration, FIG. 1 illustrates only the processing gas diffusion chamber 301 and the processing gas discharge hole 302 of some of the dividing electrodes (corner dividing electrode 32b, side dividing electrode 32a). Further, FIG. 1 shows a state in which the processing gas supply unit 42 is connected to one split electrode (corner split electrode 32b). Actually, the processing gas diffusion chamber 301 and the processing gas discharge hole 302 are provided in all the dividing electrodes (inner dividing electrode 34, intermediate dividing electrode 33, corner dividing electrode 32b, side dividing electrode 32a), and each processing gas is provided. The diffusion chamber 301 communicates with the processing gas supply unit 42.

Further, as shown in FIG. 1, the plasma processing device 1 is provided with a control unit 6. The control unit 6 is composed of a computer including a CPU (Central Processing Unit) (not shown) and a storage unit, and the storage unit vacuum exhausts the inside of the processing space 100 in which the substrate G is arranged, and the mounting table 13 and the anode electrode. A program in which a group of steps (instructions) for outputting a control signal for executing an operation of converting the etching gas supplied to and from the unit 3 into a vacuum and performing an operation of etching the substrate G is recorded. This program is stored in a storage medium such as a hard disk, a compact disk, a magnetic optical disk, or a memory card, and is installed in the storage unit from there.

Here, a plurality of divided electrodes (inner divided electrode 34, intermediate divided electrode 33, square divided electrode 32b, side divided electrode 32a) are provided to the plasma processing apparatus 1 of the present example having the above configuration. A conventional plasma processing apparatus using an anode electrode portion 3a composed of one rectangular electrode having the same short side and long side lengths as the anode electrode portion 3 instead of the anode electrode portion 3 configured in combination. To consider.

For example, using an anode electrode portion 3a composed of one rectangular electrode, the anode electrode portion 3a is connected to the grounding end 104 to form a plasma P'between the mounting table 13 and the anode electrode portion 3a, and the substrate G is formed. Consider the case where the etching process is performed. In general, when plasma is generated in the processing space 100 of the parallel plate type plasma processing apparatus 1, the region having a high plasma density tends to concentrate in the central portion of the processing space 100.

Based on the above characteristics, it can be seen that the density of plasma P'tends to decrease on the lower side (inside the processing space 100) of the anode electrode portion 3a on the corner side near the apex of the anode electrode portion 3a. The inventors are aware. As a result, when the region where the plasma P'is formed is viewed from the upper surface side, the short side and the length of the anode electrode portion 3a are schematically shown by a broken line in FIG. 3 as the outline of the region where the plasma P'is dense. The density of plasma P'is relatively high on the side of the vicinity of the side, and the density of plasma P'is relatively low on the corner side described above.

When the region on the outer peripheral side of the anode electrode portion 3a is viewed along the circumferential direction in this way, the etching process of the substrate G is performed using plasma P'in which the densities are different in the adjacent regions (corner side and side portion side). When this is performed, the etching rate and the like may change in the plane of the substrate G according to the density distribution of the plasma P', and a uniform etching treatment result may not be obtained. This tendency becomes remarkable when processing a large substrate G having a short side length of 730 mm or more as described above.

Therefore, as shown in FIG. 2, in the plasma processing device 1 of this example, the corner dividing electrode 32b constituting the outer peripheral dividing electrode (radial dividing electrode on the outer peripheral side) 32 and the grounding end 104, and the side dividing electrode Impedance adjusting portions 52, 51 for adjusting the impedance of the circuit from the mounting table 13, the corner dividing electrodes 32b, and the side dividing electrodes 32a to the grounding end 104 are provided between the 32a and the grounding end 104. ing.

As shown in FIG. 1, a plurality of high-frequency power supplies (first high-frequency power supply 152, second high-frequency power supply 162) having different frequencies are connected to the mounting table 13 which is a cathode electrode. Therefore, in the plasma processing device 1 of this example, a plurality of impedance adjusting portions 52a, 52b, 51a, 51b corresponding to these plurality of frequencies are provided between the corner dividing electrode 32b and the grounding end 104, and the side dividing electrode. It is provided in parallel between 32a and the grounding end 104. In FIG. 2, the impedance adjusting units 52a, 52b, 51a, and 51b corresponding to each of these frequencies are collectively displayed (impedance adjusting units 52, 51).

In addition to the installation of the impedance adjusting portions 52 and 51 described above, a part or all of the intermediate dividing electrode 33 and the inner dividing electrode 34 (other than the outer peripheral dividing electrode 32 divided into the corner dividing electrode 32b and the side dividing electrode 32a). The impedance adjusting unit 53 may be provided on the radial dividing electrode). At this time, a plurality of impedance adjusting units 53 and 53 are also provided for the intermediate split electrode 33 and the inner split electrode 34 in correspondence with the frequencies of the first and second high frequency power supplies 152 and 162 connected to the mounting table 13. Of course, may be provided. Note that FIG. 2 shows an example in which an impedance adjusting unit 53 is provided between the inner dividing electrode 34 and the grounding end 104, and the intermediate dividing electrode 33 is directly connected to the grounding end 104.

As shown in FIG. 2, each impedance adjusting unit 51 to 53 includes, for example, a variable capacitor 502 and an inductor 501, and a circuit from the mounting table 13 to the ground end 104 by changing the capacitance of the variable capacitor 502. Impedance can be adjusted individually.

Here, the specific configuration of the impedance adjusting units 51 to 53 is not limited to the combination of the variable capacitor 502 and the inductor 501. Examples include the case where the variable capacitor 502 is provided alone, the case where the fixed capacitor and the variable capacitor 502 are combined, and the case where the variable inductor and the fixed capacitor are combined. Further, it is not an essential requirement that the impedance adjusting units 51 to 53 can change the impedance value. For example, a fixed capacitance capacitor may be used to configure impedance adjusting units 51 to 53 having a preset impedance value.

Hereinafter, the operation of the plasma processing apparatus 1 according to the present embodiment having the above-described configuration will be described.
First, the gate valve 102 is opened, and the substrate G is carried into the processing space 100 from the adjacent vacuum transfer chamber via the carry-in outlet 101 by the transfer mechanism (the transfer mechanism and the vacuum transfer 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), while the transport mechanism is retracted from the processing space 100 and the gate valve 102 is closed.

After that, the etching gas is supplied from the processing gas supply unit 42 into the processing space 100 via the processing gas diffusion chamber 301, and the vacuum exhaust unit 12 evacuates the processing space 100 to the inside of the processing space 100. Is adjusted to a pressure atmosphere of, for example, about 0.66 to 26.6 Pa. Further, He gas for heat transfer 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 etching gas is turned into plasma in the processing space 100 due to capacitive coupling between the mounting table 13 and the anode electrode portion 3, resulting in high density. Plasma P is generated. Then, the ions in the plasma are drawn toward the substrate G by the high-frequency power for bias applied from the second high-frequency power source 162 to the mounting table 13, and the substrate G is etched.

At this time, as compared with the conventional example using the anode electrode portion 3a described with reference to FIG. 3, in the plasma processing apparatus 1 of this example, the outer peripheral dividing electrode 32 located on the outer peripheral side is divided into corners in the circumferential direction. It is divided into an electrode 32b and a side dividing electrode 32a, and impedance adjusting portions 52 and 51 are individually provided on these divided electrodes 32b and 32a.

Therefore, the impedance values of the impedance adjusting portions 52 and 51 are adjusted so that the density of the plasma P becomes the same in the region on the lower side of the corner dividing electrode 32b with respect to the region on the lower side of the side dividing electrode 32a. .. Specifically, the region where the density of plasma P is high is extended to the corner side of the anode electrode portion 3. As a result, as compared with the etching treatment by the plasma P'generated using the conventional anode electrode portion 3 described with reference to FIG. 3, the plasma P on the corner side and the side portion of the anode electrode portion 3 It is possible to reduce the density difference and perform an etching process with higher in-plane uniformity.

As a method of increasing the density of the plasma P'on the corner side of the anode electrode portion 3 as compared with the conventional method, as shown in the reference example described later, the corner split electrode 32b or the side split electrode 32a is used. In the circuit from the mounting table 13 to the grounding end 104 through the corner dividing electrode 32b using the connected impedance adjusting units 52 and 51, when compared with the same circuit on the side dividing electrode 32a side, the mounting table 13 side It is possible to exemplify a method of adjusting the impedance so that the DC component of the high frequency voltage of is about the same or larger.

Further, for example, due to the characteristics of the plasma P that tends to concentrate on the central portion side of the anode electrode portion 3, the outer peripheral side (lower side of the intermediate split electrode 33 and the outer peripheral split electrode 32) in the region on the lower side of the inner split electrode 34. In some cases, the plasma density is higher than that in the region and the etching rate tends to be higher.

In this case, the density of the plasma P in the region below the inner split electrode 34 is lowered to be aligned with the density of the plasma P on the outer peripheral side, thereby reducing the density difference of the plasma P between these regions. An etching process with higher in-plane uniformity can be performed. As a method for reducing the density of plasma P in the region below the inner dividing electrode 34, an impedance adjusting unit 53 connected to the inner dividing electrode 34 is used as shown in the reference example described later, and the mounting table 13 is used. In the circuit from the inner dividing electrode 34 to the grounding end 104, a method of adjusting the impedance so that the DC component of the high frequency voltage on the mounting table 13 side becomes smaller can be exemplified.

Further, the effect associated with performing impedance adjustment using the impedance adjusting units 51 to 53 will be mentioned. As shown in the experimental results described later, when the current flowing through each of the inner split electrodes 34, the intermediate split electrode 33, and the outer peripheral split electrode 32 of the anode electrode portion 3 increases, the plasma P causes the split electrodes 34, 33. , 32 It was found that the decrease in wall thickness (hereinafter referred to as “consumption”) due to the scraping of the surface tends to increase. Therefore, as described above, after adjusting the impedance values of the impedance adjusting units 51 to 53 so that the density of the plasma P is uniform in the plane of the anode electrode portion 3, the range that does not affect the in-plane uniformity of the etching process. By further fine-tuning the impedance values of the impedance adjusting units 51 to 53 so that the current flowing through each circuit from the mounting table 13 to the grounding end 104 becomes as small as possible, the divided electrodes 34, 33, and 32 are consumed. Can also be reduced.

When plasma P is generated in the processing space 100 using the anode electrode portion 3 for which the impedance adjustment has been performed as described above and etching processing is performed for a preset time, power is supplied and processed from the high frequency power supplies 152 and 162, respectively. The etching gas supply from the gas supply unit 42 and the vacuum exhaust in the processing space 100 are stopped, and the substrate G is carried out in the order opposite to that at the time of carrying in.

According to the plasma processing apparatus 1 according to the present embodiment, the following effects are obtained. In a parallel plate type plasma processing device 1 that performs etching processing on a rectangular substrate G, an outer peripheral split electrode 32 that is arranged so as to face the substrate G and is located on the outer peripheral side of an anode electrode portion 3 having a rectangular planar shape. Is divided into a corner dividing electrode 32b located on the corner side and a side dividing electrode 32a located on the side. Then, impedance adjusting units 51 to 53 for adjusting the impedance of the circuit from the mounting table (cathode electrode) 13 to the grounding end 104 via the plasma P are provided. As a result, the substrate G at the position corresponding to the corner portion and the side portion can be uniformly etched.

The above-mentioned effect can be obtained only when the plasma processing apparatus 1 is configured as the etching apparatus for performing the etching process. Similarly, when 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 of a resist film, uniform processing is performed in the plane of the substrate G. It can be performed.

Here, the anode electrode portion 3 may be divided into at least two in the radial direction. Further, the "diametrically divided electrode located on the outer peripheral side" refers to the outer edge (the short side described above) of the anode electrode portion 3 from the center of the anode electrode portion 3 among the plurality of radially divided electrodes. If it is arranged in a region outside 1/2 of the distance to (or long side), it is described above by dividing the corner dividing electrode 32b and the side dividing electrode 32a and adjusting the impedance. It is possible to exert the action effect of.

As described with reference to FIG. 2, the anode electrode portion 3 of this example has four corner division electrodes 32b located on the corner side among the outer circumference division electrodes 32 located on the outermost side. It is connected to the impedance adjusting unit 52, and four side portion dividing electrodes 32a located on the side portion side are connected to the common impedance adjusting unit 51. On the other hand, it is not an indispensable requirement to make the impedance adjustment unit 52 common to the four corner division electrodes 32b and the impedance adjustment unit 51 to the four side division electrodes 32a. Impedance adjusting units 52 and 51 may be provided individually for the divided electrode 32b and each side divided electrode 32a.

Further, it is not an essential requirement to connect both the corner dividing electrode 32b and the side dividing electrode 32a to the impedance adjusting portions 52 and 51. If at least one of the corner split electrode 32b or the side split electrode 32a is connected to the impedance adjusting portions 52 and 51 to adjust the impedance, the density difference of the plasma P between the corner side and the side portion side of the anode electrode portion 3 is adjusted. Can be reduced to obtain the effect of improving the in-plane uniformity of the plasma treatment.

Further, the radial dividing electrode for dividing in the circumferential direction is not limited to the outer peripheral dividing electrode 32 arranged on the outermost peripheral side. Of the three radial division electrodes (inner division electrode 34, intermediate division electrode 33, outer peripheral division electrode 32), for example, the intermediate division electrode 33 may be divided in the circumferential direction. When the intermediate split electrode 33 is divided into the corner split electrode 33b and the side split electrode 33a as in the anode electrode portion 3b shown in FIG. 4, the corner split electrode 33b is the plasma P on the corner side of the anode electrode portion 3. When arranged in a region capable of affecting the density of the above-mentioned impedance, at least one of the corner dividing electrode 33b and the side dividing electrode 33a is connected to the impedance adjusting portions 52 and 51. The adjustment can contribute to the improvement of the in-plane uniformity of the plasma treatment.

In addition, the number of radial dividing electrodes divided in the circumferential direction is not limited to one. In addition to dividing the outer peripheral split electrode 32 into the square split electrode 32b and the side split electrode 32a with the outer peripheral split electrode 32 oriented in the circumferential direction as in the anode electrode portion 3c shown in FIG. 5, the intermediate split electrode 33 is directed in the circumferential direction. The corner division electrode 33b and the side division electrode 33a may be divided. In this case, the corner dividing electrode 33b of the intermediate dividing electrode 33 is preferably connected to an impedance adjusting portion different from the corner dividing electrode 32b of the outer peripheral dividing electrode 32, and the side dividing electrode of the intermediate dividing electrode 33. It is preferable that the 33a is connected to an impedance adjusting portion different from that of the side dividing electrode 32a of the outer peripheral dividing electrode 32.

For example, in the anode electrode portion 3c shown in FIG. 5, when (i) the corner split electrode 33b and the side split electrode 33a of the intermediate split electrode 33 are connected to a common impedance adjusting portion, (ii) each corner split electrode In a circuit in which 33b and the side split electrode 33a are connected to separate impedance adjustment sections, and the mounting base 13 passes through the split electrodes 33b and 33a via the capacitive coupling plasma P to reach the grounding end 104, for example, from the plasma P side. As seen, when the impedance is adjusted so that the impedances per unit area of the divided electrodes 33b and 33a are the same, (iii) the impedance adjusting unit is not connected to the corner divided electrodes 33b and the side divided electrodes 33a of the intermediate divided electrodes 33. Consider the case where it is directly connected to the ground electrode 104. In these cases, the state of the plasma P formed on the lower side of each of the divided electrodes 33b and 33a is the same as the state of the plasma P formed on the lower side of the undivided intermediate divided electrode 33.

Therefore, in the cases of (i) to (iii), even if the intermediate split electrode 33 is configuredly divided into a plurality of split electrodes 33b and 33a, they are integrally configured in forming the capacitively coupled plasma P. It can be said that there is no difference from the case where the intermediate split electrode 33 is used. For example, the intermediate split electrode 33 and the inner split electrode 34 shown in FIG. 2 include those having a configuration of any one of (i) to (iii) after being split.

Further, the shape of the radial division electrode obtained by dividing the anode electrode portion 3 into a plurality of parts in the radial direction is a rectangular shape (inner division electrode 34) and an annular shape (intermediate division electrode 33) shown in FIG. The case is not limited to the case of the outer peripheral dividing electrode 32). For example, the inner dividing electrode 34 may be formed in an elliptical shape, and the intermediate dividing electrode 33 may be formed in an elliptical ring shape surrounding the outer circumference of the inner dividing electrode 34. In this case, the outer peripheral split electrode 32 has the shape of the remaining region obtained by removing the inner split electrode 34 and the intermediate split electrode 33 on the ellipse from the rectangular anode electrode portion 3. Therefore, the shapes of the corner dividing electrode 32b and the side dividing electrode 32a obtained by dividing the outer peripheral dividing electrode 32 and the like in the circumferential direction are not limited to the example of FIG. 2, and the shape of the outer peripheral dividing electrode 32 and the like. Of course, it is determined as appropriate according to the situation.

(Experiment 1)
While adjusting the impedance using the impedance adjusting units 53 and 54 with respect to the anode electrode portion 3d provided with the three radial dividing electrodes (inner dividing electrode 34, intermediate dividing electrode 33, and outer peripheral dividing electrode 32) shown in FIG. The current value was measured. In the anode electrode portion 3d shown in FIG. 6, the description of the connection of the outer peripheral split electrode 32 to the grounding end 104 is omitted.
A. Experimental conditions
(Reference Example 1-1) Using the plasma processing device 1 provided with the anode electrode portion 3d shown in FIG. 6, impedance between the inner split electrode 34 and the ground end 104 and between the intermediate split electrode 33 and the ground end 104. Adjustment units 53 and 54 were provided, the capacitance of the variable capacitance capacitor 502 provided in the impedance adjustment unit 53 on the inner split electrode 34 side was changed, and the current flowing through each circuit was measured by current meters 503 and 504. During this operation period, the capacitance of the variable capacitance capacitor 502 on the intermediate split electrode 33 side was fixed. Further, the change in the voltage on the mounting table 13 (cathode electrode) side was measured by a voltmeter (not shown) provided on the matching unit 151 on the first high frequency power supply 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 atm standard), and the pressure in the processing space 100 was adjusted to 1.33 Pa (10 mTorr). Further, 22 kW of high frequency power was supplied from each of the first high frequency power supply 152 and the second high frequency power supply 162.
(Reference Example 1-2) Under the same conditions as in Reference Example 1-1, the capacitance of the variable capacitance capacitor 502 provided in the impedance adjusting unit 54 on the intermediate dividing electrode 33 side is changed, and the current flowing through each circuit and the current flowing through each circuit are changed. The voltage on the mounting table 13 side was measured. During this operation period, the capacitance of the variable capacitance capacitor 502 on the inner split electrode 34 side was 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. The horizontal axis of FIGS. 7 and 8 shows the dial value of the variable capacitor 502. The smaller the value of the dial value, the larger the capacitance of the variable capacitance capacitor 502, and the larger the dial value, the smaller the capacitance. The vertical axis on the left side of FIGS. 7 and 8 shows the current values of the divided electrodes 34 and 33, and the vertical axis on the right side shows the voltage value on the mounting table 13 side. In each figure, the change in the current value on the inner dividing electrode 34 side is shown by a dashed line, and the change in the current value on the intermediate dividing electrode 33 side is shown by a solid line. Further, the change in the voltage value on the mounting table 13 side is shown by a broken line.

According to the result of Reference Example 1-1 shown in FIG. 7, the dial value of the variable capacitance capacitor 502 provided in the impedance adjusting unit 53 is gradually increased (the capacitance of the variable capacitance capacitor 502 is gradually decreased). ), The current value on the inner split electrode 34 side increases, and after the dial value peaks in the range of 3.5 to 4.5, as the dial value is further increased, the inner split electrode 34 side The current value gradually decreased.
On the other hand, during the above-mentioned dial operation, the current value on the intermediate split electrode 33 side remained low and hardly changed.

Further, during the above-mentioned dial operation period, a phenomenon was observed in which the voltage value on the mounting table 13 side decreased in response to the increase or decrease in the current value on the inner split electrode 34 side. Therefore, it can be evaluated that the change in the current value flowing through the inner split electrode 34 is generated by the high frequency power supplied from the mounting table 13 side being drawn into the inner split electrode 34 side via the plasma P. ..

On the other hand, the results of Reference Example 1-2 shown in FIG. 8 were in contrast to the experimental results of Reference Example 1-1 shown in FIG.
That is, when the dial value of the variable capacitance capacitor 502 provided in the impedance adjusting unit 54 is gradually increased, the current value on the intermediate dividing electrode 33 side increases, and the dial value is in the range of about 2 to 4. After showing the peak, the current value on the intermediate dividing electrode 33 side gradually decreased as the dial value was further increased.
On the other hand, during the above-mentioned dial operation, the current value on the inner split electrode 34 side remained low and hardly changed.

Further, during the above-mentioned dial operation period, a phenomenon was observed in which the voltage value on the mounting table 13 side decreased in response to the increase / decrease in the current value flowing through the intermediate dividing electrode 33. Therefore, it can be evaluated that the change in the current value on the intermediate dividing electrode 33 side is generated by the high frequency power supplied from the mounting table 13 side being drawn into the intermediate dividing electrode 33 side via the plasma P. ..

Summarizing the above experimental results, the intermediate dividing electrode 33 and the inner dividing electrode 34 are independent of each other by adjusting the impedance values of the impedance adjusting portions 53 and 54 provided on the intermediate dividing electrode 33 and the inner dividing electrode 34. It was confirmed that the current flowing through the circuit including the divided electrodes 33 and 34 (the circuit from the mounting table 13 to the grounding end 104) can be adjusted to increase or decrease.
It can be said that this result is also valid when the impedance values of the impedance adjusting units 52 and 51 are adjusted between the corner dividing electrode 32b and the side dividing electrode 32a shown in FIG.

(Experiment 2) The substrate G was etched using the plasma processing apparatus 1 provided with the anode electrode portion 3d shown in FIG.
A. Experimental conditions
(Reference Example 2-1) For reference, set the dial value of the variable capacitor 502 in each of the impedance adjustment units 53 and 54 at the position where the DC component (Vdc) of the voltage value measured on the mounting table 13 side is minimized. The substrate G was etched under the same conditions as in Example 1-1. The dial value of the variable capacitor 502 in the impedance adjusting unit 53 on the inner dividing electrode 34 side is 4.5, which is a position corresponding to the peak of the current value on the inner dividing electrode 34 side in FIG. The dial value of the variable capacitor 502 on the intermediate dividing electrode 33 side is 3.0, which is a position corresponding to the peak of the current value on the intermediate dividing electrode 33 side in FIG.
(Reference Example 2-2) For reference, set the dial value of the variable capacitor 502 in each impedance adjusting unit 53, 54 at the position where the DC component (Vdc) of the voltage value measured on the mounting table 13 side is maximized. The substrate G was etched under the same conditions as in Example 1-1. The dial value of the variable capacitor 502 in the impedance adjusting unit 53 on the inner split electrode 34 side is 8.0, which is the position where the current value on the inner split electrode 34 side in FIG. 7 is the smallest. The dial value of the variable capacitor 502 on the intermediate dividing electrode 33 side is 8.0, which is the position where the current value on the intermediate dividing electrode 33 side in FIG. 8 is the smallest.
(Comparative Example 2) The substrate G was etched without providing the impedance adjusting portions 53 and 54 between the inner split electrode 34 and the grounded end 104 and between the intermediate split electrode 33 and the grounded end 104.

B. Experimental Results The results of Reference Examples 2-1 and 2-2 and Comparative Example 2 are shown in FIG. The horizontal axis of FIG. 9 shows the DC component of the voltage value measured on the mounting table 13 side. The vertical axis on the left side of FIG. 9 shows the etching rate per unit time, and the vertical axis on the right side is the uniformity of the etching rate in the plane of the substrate G ({(standard deviation σ) / (mean value Ave)} ×. 100 [%]) is shown.
In FIG. 9, the white circle plot shows the lower region of the inner dividing electrode 34, and the black circle plot shows the average etching rate of the substrate G in the lower region of the intermediate dividing electrode 33. The white horizontal bar plot shows the maximum etching rate in the lower region of the outer peripheral dividing electrode 32, and the black-painted horizontal bar plot shows the minimum etching rate in the lower region of the outer peripheral dividing electrode 32. ing. Further, the black-painted diamond-shaped plot shows the average value of the etching rates in the plane of the substrate G, and the cross-marked plot shows 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 minimum, the etching rate of each region and the average in-plane etching rate of the substrate G becomes small (Reference Example). 2-1) When the DC component was the maximum, the etching rate of each region and the average in-plane etching rate of the substrate G increased. Therefore, it was confirmed that the etching rate of the substrate G can be changed by adjusting the impedance value using the impedance adjusting units 53 and 54.
It can be said that this result also holds true when the impedance values of the impedance adjusting units 52 and 51 are adjusted between the corner dividing electrode 32b and the side dividing electrode 32a shown in FIG.

On the other hand, in Comparative Example 2 in which the impedance adjusting portions 53 and 54 are not provided on the grounding end 104 side of the inner divided electrode 34 and the intermediate divided electrode 33, in the region on the lower side of the inner divided electrode 34 and the intermediate divided electrode 33. An upwardly convex etching rate distribution was formed in which the etching rate was increased and the etching rate was decreased in the region on the lower side of the outer peripheral dividing electrode 32. As a result, the uniformity value of the etching rate was worse than that of Reference Examples 2-1 and 2-2. Further, 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 grounding point.

(Experiment 3) The amount of wear on the anode electrode portion 3 side was measured using the plasma processing apparatus 1 provided with the anode electrode portion 3d shown in FIG.
A. Experimental conditions
(Reference Example 3-1) A test piece made of an aluminum chip is attached to the lower surface of the inner split electrode 34, and the same operation as in Reference Example 1-1 is performed to change the current value flowing through the circuit on the inner split electrode 34 side. While generating plasma P for a predetermined time, the amount of consumption of the test piece was measured.
(Reference Example 3-2) The test piece of the intermediate split electrode 33 was attached, the same operation as in Reference Example 1-2 was performed, and the same experiment as in Reference Example 3-1 was performed.

B. Experimental Results The results of Reference Examples 3-1 and 3-2 are shown in FIGS. 10 and 11, respectively. The horizontal axis of these figures shows the current value flowing through the divided electrodes 34 and 33, and the vertical axis shows the sputtering amount of the test piece. The amount of sputtering at each current value is shown in a black diamond plot. Further, in each figure, the sputtering amount of the test piece when the impedance adjusting units 53 and 54 are not provided is shown by a broken line.

According to the results of Reference Examples 3-1 and 3-2 shown in FIGS. 10 and 11, in any of the inner split electrode 34 and the intermediate split electrode 33, as the current flowing through the split electrodes 34 and 33 increases, , The amount of sputtering of the test piece is large. Therefore, in the substrate G arranged in the region below each of the divided electrodes 34 and 33, the impedance is adjusted so that the current flowing through the divided electrodes 34 and 33 becomes small within the range in which the desired etching rate can be obtained. By adjusting the impedance values of the parts 53 and 54, the consumption of the inner split electrode 34 and the intermediate split electrode 33 can be reduced.
It can be said that this result is also valid for the corner split electrode 32b and the side split electrode 32a shown in FIG.

G Substrate P, P'Plasma 1 Plasma processing device 13 Mounting table 151 Matching device 152 First high frequency power supply 161 Matching device 162 Second high frequency power supply 3, 3a to 3d
Anode electrode portion 32 Outer peripheral split electrode 32a Side split electrode 32b Square split electrode 33 Intermediate split electrode 34 Inner split electrode 503, 504
Ammeter 51-54 Impedance adjustment unit 6 Control unit

Claims (6)

In a plasma processing apparatus that executes plasma processing with a plasma-generated processing gas on a rectangular substrate to be processed in a vacuum-exhausted processing container.
A cathode electrode, which is arranged in the processing container in a state of being insulated from the processing container, connected to a high-frequency power supply via a matching circuit, and on which a rectangular substrate to be processed is placed.
It is provided with an anode electrode portion which is arranged in a state of being insulated from the processing container so as to face the cathode electrode and has a rectangular planar shape corresponding to the substrate to be processed.
The anode electrode portion is
When the direction from the center side to the outer peripheral side of the anode electrode portion is the radial direction, the anode electrode portion is divided into a plurality of radial division electrodes toward the radial direction, and the radial division electrodes are each insulated from each other. It is connected to the grounding end with
Among the plurality of radial split electrodes, the radial split electrodes located on the outer peripheral side are located on the corner side of the anode electrode portion in the circumferential direction, and are arranged adjacent to each other on the central side. A plurality of corner-divided electrodes having a side extending along the shape of the other radial-divided electrode, and a plurality of corner-divided electrodes located on the side of the other radial-divided electrode, respectively. is divided into a plurality of side portions divided electrodes which have a side extending along a shape, these corner portions divided electrode and the side portions divided electrodes are each a that is connected to the ground terminal in a state of being insulated from each other,
The impedance of the circuit from the cathode electrode to the grounded end of each corner divided electrode or the side divided electrode via plasma is adjusted on at least one grounded end side of the corner divided electrode and the side divided electrode. A plasma processing device characterized in that an impedance adjusting unit is provided for the operation. The first aspect of the present invention, wherein the radial dividing electrode divided into the corner divided electrode and the side divided electrode is located on the outermost peripheral side of the plurality of radial divided electrodes. Plasma processing equipment. The impedance adjusting unit provided on at least one of the corner dividing electrode and the side dividing electrode is shared with respect to the plurality of corner dividing electrodes or the plurality of side dividing electrodes. The plasma processing apparatus according to claim 1 or 2. At least one of the radial division electrodes other than the radial division electrode divided into the corner division electrode and the side division electrode is provided from the cathode electrode to the grounding end of each radial division electrode via plasma. The plasma processing apparatus according to any one of claims 1 to 3, wherein an impedance adjusting unit for adjusting the impedance of the circuit to be reached is provided. A plurality of high-frequency power supplies having different frequencies are connected to the cathode electrode, and a plurality of impedance adjustments corresponding to each frequency of the plurality of high-frequency power supplies are provided on the grounding end side of the divided electrode provided with the impedance adjusting unit. The plasma processing apparatus according to any one of claims 1 to 4, wherein the units are provided in parallel. The plasma processing apparatus according to any one of claims 1 to 5, wherein the impedance adjusting unit is configured so that the impedance value can be changed.