TWI781988B - Substrate processing apparatus - Google Patents

Abstract

A substrate processing apparatus includes a process chamber, a stage that is disposed in the process chamber and on which a substrate is placeable, a moving mechanism, and a focus ring. The focus ring is disposed on the stage and includes an inner focus ring disposed close to the substrate placed on the stage, a middle focus ring that is disposed outside of the inner focus ring and is movable in a vertical direction by the moving mechanism, and an outer focus ring that is disposed outside of the middle focus ring.

Description

Substrate processing equipment

The present invention relates to a substrate processing apparatus.

In a plasma etching apparatus, a focus ring is provided along the outer periphery of a semiconductor wafer (hereinafter referred to as "wafer") (for example, refer to Patent Document 1). The function of the focus ring is to control the plasma near the outer periphery of the wafer to improve the uniformity of the etching rate in the wafer surface.

The etch rate at the edge of the wafer varies with the height of the focus ring. Therefore, if the height of the focus ring is changed due to the loss of the focus ring, the etching rate at the edge of the wafer will be higher than that at the center or middle of the wafer, etc., and it becomes difficult to control the etching at the edge of the wafer. characteristic. In view of this, in Patent Document 1, a driving unit for driving the focus ring up and down is provided to control the position of the top surface of the focus ring and improve the controllability of the edge of the wafer. [Prior art documents] [Patent documents]

[Patent Document 1] Japanese Patent Laid-Open No. 2008-244274

[Problem to be solved by the invention]

However, in Patent Document 1, the inner focus ring is kept fixed among the focus rings divided into two parts, and only the outer focus ring is moved up and down. In this mechanism, if the outer focus ring is moved up and down, the etching rate of the entire wafer will be shifted. Therefore, the etching properties of the entire wafer vary, and it is difficult to control the etching properties of only the edge portion of the wafer.

In view of the above-mentioned problems, at one level, the object of the present invention is to maintain the processing characteristics for the entire in-plane of the substrate, and at the same time control the processing characteristics for the edge portion of the substrate. [Technical means to solve the problem]

In order to solve the above problems, an aspect of the present invention provides a substrate processing apparatus, which has a focus ring; the focus ring includes: an inner focus ring disposed near a substrate that is placed on a work table in a processing chamber; a central focus ring , which is arranged outside the inner focus ring, and can move up and down by a moving mechanism; and the outer focus ring, which is arranged outside the central focus ring. [Effect of Invention]

According to one aspect of the present invention, it is possible to maintain the processing characteristics for the entire in-plane of the substrate while controlling the processing characteristics for the edge portion of the substrate.

Embodiments for implementing the present invention will be described below with reference to the drawings. In addition, in this specification and drawings, the same code|symbol is attached|subjected to the structure which is substantially the same, and repeated description is abbreviate|omitted.

[Substrate Processing Apparatus] First, an example of the structure of a substrate processing apparatus 5 according to an embodiment of the present invention will be described with reference to FIG. 1 . FIG. 1 shows an example of the structure of the substrate processing apparatus 5 of this embodiment. In this embodiment, description will be given by taking a capacitively coupled parallel plate plasma processing apparatus as the substrate processing apparatus 5 as an example.

The substrate processing apparatus 5 has a processing chamber 10 which is, for example, a cylindrical vacuum container made of metal such as aluminum or stainless steel. The processing chamber 10 is an example of a processing container, and the inside thereof is a processing chamber for performing plasma processing. The processing chamber 10 is grounded.

In the center of the lower part of the processing chamber 10, a disc-shaped work table 12 is arranged, which is also used as a substrate holding table for the lower electrode, and a wafer W as an object to be processed, for example, is placed thereon. The work table 12 is made of aluminum, for example, and is supported by a conductive cylindrical support portion 16 extending vertically upward from the bottom of the processing chamber 10, and a case 100 provided adjacent to the inside thereof.

An annular exhaust path 18 is formed between the conductive cylindrical support portion 16 and the inner wall of the processing chamber 10 . An annular baffle 20 is installed at the upper part or the inlet of the exhaust path 18 ; an exhaust port 22 is provided at the bottom. In order to make the gas flow in the processing chamber 10 uniform with respect to the axis of the wafer W on the work table 12, it is preferable to configure a plurality of exhaust ports 22 at equal intervals in the circumferential direction.

Each exhaust port 22 is connected to an exhaust device 26 via an exhaust pipe 24 . The exhaust device 26 has a vacuum pump such as a turbomolecular pump, and can reduce the pressure of the plasma generation space S in the processing chamber 10 to a desired vacuum degree. On the outside of the side wall of the processing chamber 10, a gate valve 28 for opening and closing the loading and unloading port 27 of the wafer W is attached.

The workpiece table 12 is electrically connected to the second high-frequency power supply 30 via a matching unit 32 and a power supply rod 34 . The second high-frequency power supply 30 can output a high-frequency LF of a first frequency (for example, 13.56 MHz) with variable power, and is suitable for controlling the energy for introducing ions into the wafer W. The matching unit 32 accommodates a variable reactance matching circuit for matching the impedance on the second high-frequency power supply 30 side with the impedance on the load (plasma, etc.) side.

On the top surface of the workpiece table 12, an electrostatic chuck 36 for holding the wafer W by electrostatic attraction is provided. The electrostatic chuck 36 is sandwiched between a pair of insulating films 36b and an electrode 36a formed by a conductive film. The electrode 36a is electrically connected to the DC power supply 40 through the switch 42 and the covered wire 43 . The wafer W is attracted and held on the electrostatic chuck 36 through electrostatic force by the DC current supplied from the DC power supply 40 .

Inside the work table 12, for example, an annular refrigerant flow path 44 extending in the circumferential direction is provided. From the cooling unit through the pipes 46 and 48 , a refrigerant of a predetermined temperature, such as cooling water cw, is circulated to the refrigerant channel 44 ; the temperature of the wafer W on the electrostatic chuck 36 can be controlled by the temperature of the refrigerant. Moreover, the heat dissipation gas from the heat dissipation gas supply part, such as helium, is supplied between the top surface of the electrostatic chuck 36 and the back surface of the wafer W through the gas supply pipe 50 . In addition, in order to carry in and carry out the wafer W, vertically penetrating the workpiece table 12 and vertically movable ejector pins, its elevating mechanism, and the like are provided.

The air jet head 51 provided at the ceiling opening of the processing chamber 10 is installed so as to close the ceiling opening of the processing chamber 10 through a seal ring 54 covering the outer edge thereof. The jet head 51 is formed of silicon. The air jet head 51 also functions as a counter electrode (upper electrode) facing the workpiece table 12 (lower electrode).

In the gas shower head 51, a gas introduction port 56 for introducing gas is formed. Inside the gas shower head 51, a diffusion chamber 58 branched from the gas introduction port 56 is provided. The gas output from the gas supply source 66 is supplied to the diffusion chamber 58 through the gas introduction port 56 , diffused, and introduced into the plasma generation space S through the plurality of gas supply holes 52 .

The jet head 51 is electrically connected to the first high-frequency power source 57 via a matching unit 59 and a power supply line 60 . The first high-frequency power supply 57 can produce high-frequency HF for plasma with variable power output, which is suitable for generating plasma with high-frequency discharge, and is a second frequency higher than the first frequency (such as 40MHz). The matching unit 59 accommodates a variable reactance matching circuit for matching the impedance on the side of the first high-frequency power supply 57 with the impedance on the side of the load (plasma, etc.).

The control unit 74 includes, for example, a microcomputer, and controls the operation of each department in the substrate processing apparatus 5 and the operation of the entire apparatus. As for each department in the substrate processing apparatus 5, the exhaust device 26, the first high-frequency power supply 57, the second high-frequency power supply 30, the matching unit 32, the matching unit 59, the switch 42 for the electrostatic chuck, A gas supply source 66, a cooling unit, a heat radiation gas supply unit, and the like.

When performing various processes such as etching in the substrate processing apparatus 5 , the gate valve 28 is first opened, and the wafer W is carried into the processing chamber 10 and placed on the electrostatic chuck 36 . Then, after closing the gate valve 28, a predetermined gas is introduced into the processing chamber 10 from the gas supply source 66 at a predetermined flow rate and flow ratio, and then the pressure in the processing chamber 10 is decompressed to a predetermined setting by the exhaust device 26. value. Furthermore, the first high-frequency power supply 57 is turned on (on), and the high-frequency HF for generating plasma is output at a predetermined power, and then supplied to the jet head 51 through the matching unit 59 and the power supply line 60 .

On the other hand, when the high-frequency LF used for controlling ion introduction is applied, the second high-frequency power supply 30 is turned on, and the high-frequency LF is output with a predetermined power, and then passes through the matching device 32 and the power supply bar 34 to Applied to the workpiece table 12. Furthermore, the heat dissipation gas is supplied from the heat dissipation gas supply part to the contact surface between the electrostatic chuck 36 and the wafer W, and at the same time the switch 42 is turned on, and the DC voltage from the DC power supply 40 is applied to the electrode 36a of the electrostatic chuck 36, Then, the heat dissipation gas is locked into the above-mentioned contact surface by electrostatic adsorption force.

[Focus Ring Divided into Three Parts] A focus ring FR that surrounds the outer edge of the wafer W in a ring shape is provided on the outer peripheral side of the work table 12 . The function of the focus ring FR is to control the plasma on the outer peripheral side of the wafer W, so as to improve the processing uniformity such as the in-plane etching rate of the wafer W.

The etching rate at the edge of the wafer W varies with the height of the focus ring FR. Therefore, if the height of the focus ring FR varies due to loss, the etching rate at the edge of the wafer W will vary, making it difficult to control the edge.

In view of this, the focus ring FR of this embodiment is divided into three parts, including an inner focus ring 38i, a central focus ring 38m, and an outer focus ring 38o, and the central focus ring 38m can be moved up and down by the moving mechanism 200. The moving mechanism 200 has an ejector pin 102 . The ejector pin 102 moves up and down through the member 104 a and the bearing part 105 by the power generated by the piezoelectric actuator 101 . Thereby, the connection part 103 moves up and down, and the central focus ring 38m connected with the connection part 103 also moves up and down along with it. In addition, in this embodiment, the edge portion of the wafer W refers to an annular portion of 140 mm to 150 mm along the radial direction from the center of the wafer W.

(Structure of Focus Ring) Next, the structure of the focus ring FR and its periphery will be described in detail with reference to FIGS. 2 and 3 . Furthermore, the vertical movement of the center focus ring 38m will be described with reference to FIG. 4 .

FIG. 2 is an enlarged diagram illustrating an example of a longitudinal section of the focus ring FR and its periphery. In FIG. 2, the focus ring FR, the moving mechanism 200, and the piezoelectric actuator 101 of this embodiment are shown.

Figure 3(a) is a perspective view of each part of the focus ring FR divided into three parts, Figure 3(b) is a top view of each part of the focus ring FR divided into three parts, Figure 3(c) is the A-A section of Figure 3(b) Fig. 3 (d) is the B-B sectional view of Fig. 3 (b).

As shown in FIG. 2 and FIG. 3 , the inner focus ring 38i is disposed near the outermost periphery of the wafer W to surround the wafer W from below, and is the innermost member of the focus ring FR. The central focus ring 38m is a member provided outside the inner focus ring 38i to surround the inner focus ring 38i. The outer focus ring 38o is a member provided outside the central focus ring 38m, and is the outermost member of the focus ring FR. The inner focus ring 38i and the outer focus ring 38o are fixed on the top surface of the electrostatic chuck 36 . The central focus ring 38m can be moved up and down by the moving mechanism 200 .

The central focus ring 38m has an annular portion 38m1 surrounding the peripheral portion of the wafer W and three claw portions 38m2, as shown in FIGS. 3(a) and (b). The claws 38m2 are arranged at equal intervals on the outer peripheral side of the annular portion 38m1, and are rectangular members protruding from the outer peripheral side of the annular portion 38m1. As shown in FIG. 2, the longitudinal section of the annular portion 38m1 is L-shaped. When the central focus ring 38m is lifted up, the L-shaped step portion of the annular portion 38m1 changes from the state of contacting the step portion of the inner focus ring 38i having an L-shaped longitudinal section to a separated state.

(Movement Mechanism and Drive Unit) The ring-shaped coupling part 103 is connected to the claw part 38m2 of the center focus ring 38m. The connection part 103 moves up and down inside the space 16 a provided in the conductive cylindrical support part 16 .

The moving mechanism 200 is a mechanism for moving the central focus ring 38m up and down. The moving mechanism 200 includes the ejector pin 102 and the bearing part 105 . The moving mechanism 200 is installed on the casing 100 arranged around the workpiece table 12 , and moves up and down by the power of the piezoelectric actuator 101 installed on the casing 100 . The push pin 102 can also be formed of sapphire.

The casing 100 is formed of an insulating material such as alumina. The casing 100 is placed inside the conductive cylindrical support part 16 , and the side part and the bottom are adjacent to the conductive cylindrical support part 16 . A concave portion 100 a is formed on the inner lower side of the housing 100 . Inside the casing 100, a moving mechanism 200 is provided. The ejector pin 102 penetrates through the housing 100 and the workpiece table 12 , and contacts the bottom surface of the connecting portion 103 in the space 16 a of the conductive cylindrical support portion 16 . The bearing portion 105 is fitted to a member 104 a provided inside the casing 100 . The pinhole of the ejector pin 102 is provided with an O-ring 111 for dividing the vacuum space and the atmospheric space.

The lower end of the ejector pin 102 is fitted into the recessed portion 105a at the front end of the bearing portion 105 from above. By the positioning performed by the piezoelectric actuator 101, the bearing part 105 moves up and down through the member 104a, and the ejector pin 102 moves up and down, and pushes up or presses down the bottom surface of the connecting part 103. Thereby, the central focus ring 38 m moves up and down via the coupling portion 103 .

The upper end of the piezoelectric actuator 101 is fixed to the member 104a with a screw 104c; the lower end of the piezoelectric actuator 101 is fixed to the member 104b with a screw 104d. Accordingly, the piezoelectric actuator 101 is fixed on the casing 100 by being tied between the components 104 a and 104 b.

The piezoelectric actuator 101 is a positioning element using a piezoelectric effect, and can perform positioning with a resolution of 0.006 mm (6 μm). The ejector pin 102 moves up and down according to the displacement of the piezoelectric actuator 101 in the up and down direction. In this way, the central focus ring 38m will only move by a predetermined height with 0.006mm as the smallest unit.

The ejector pins 102 are provided corresponding to three claws 38m2 provided at equal intervals in the circumferential direction of the central focus ring 38m as shown in FIGS. 3( a ) and ( b ). With this structure, the ejector pin 102 pushes up the central focus ring 38m from three places through the ring-shaped connecting portion 103 to a predetermined height.

On the bottom surface of the outer focus ring 38o, above the claw portion 38m2 of the central focus ring 38m, a concave portion 138 wider than the claw portion 38m2 is formed. Once the central focus ring 38m is moved to the uppermost position by being pushed up by the ejector pin 102 , the claw portion 38m2 will be retracted into the recessed portion 138 . This allows the outer focus ring 38o to remain fixed while the central focus ring 38m is pushed up.

In Fig. 3(d) showing the B-B section of Fig. 3(b), what is depicted is that there is no space for the recess 138 and the ejector pin 102, and by allowing the ejector pin 102 to move upwards, the annular The connection part 103 is pushed up in the space 16a of the conductive cylindrical support part 16.

Back to FIG. 2 ; the piezoelectric actuator 101 is located in the inner space of the housing 100 below the ejector pin 102 , and is arranged one-to-one with the ejector pin 102 . That is, three moving mechanisms 200 and piezoelectric actuators 101 are provided in a one-to-one correspondence with the three ejector pins 102 inside the casing 100 . The members 104a, 104b are annular members, and the three piezoelectric actuators 101 are connected to each other by the members 104a, 104b locked up and down. Moreover, the piezoelectric actuator 101 of this embodiment is an example of a drive part.

As described above, in this structure, the workpiece table 12 and the electrostatic chuck 36 are supported by the casing 100 , and the moving mechanism 200 and the drive unit are installed on the casing 100 . This eliminates the need to change the design of the electrostatic chuck 36 , and only the center focus ring 38 m can be moved up and down using the existing electrostatic chuck 36 . Furthermore, as shown in Figure 2, in the structure of this embodiment, a predetermined space is provided between the top surface of the electrostatic chuck 36 and the bottom surface of the central focus ring 38m, so that the central focus ring 38m can not only move upwards, You can also move down. In this way, the central focus ring 38m can not only move upward, but also move downward by a predetermined height in a predetermined space. By making the central focus ring 38m movable not only upward but also downward, the control range of the sheath can be expanded.

However, the drive unit is not limited to the piezoelectric actuator 101, and a motor capable of positioning control with a resolution of 0.006 mm may be used. In addition, there may be one or plural driving units. Furthermore, the driving part can also be a motor that moves up and down the "ejection pin for pushing up the wafer W" in common. In this case, it is necessary to use a gear and a power switching unit to switch and transmit the power of the motor between the ejector pins for the wafer W and the ejector pins 102 for the central focus ring 38m, and to The resolution of 0.006mm controls the mechanism that the ejector pin 102 moves up and down. However, since the central focus ring 38m arranged on the outer periphery of the wafer W of 300mm has a relatively large diameter of about 310mm, it is preferable to provide a drive unit for each ejector pin 102 as in this embodiment.

The control unit 74 controls the positioning of the piezoelectric actuator 101 so that the vertical displacement of the piezoelectric actuator 101 corresponds to the loss of the central focus ring 38m.

If the wafer W is at the same height as the top surface of the focus ring FR, the height of the sheath on the wafer W being etched can be made the same as the height of the sheath on the focus ring FR. Then, by making the height of the sheath uniform, the uniformity of the etching rate over the entire wafer W in the plane can be improved.

If the focus ring FR is a new product, the height of the sheath on the wafer W being etched will be the same (flat) as that of the sheath on the focus ring FR, so the etching rate will be uniform across the entire surface of the wafer W. . At this time, as shown in FIG. 4(a-1), the central focus ring 38m is not pushed up by the ejector pin 102 (0mm). Also, Fig. 4(a-1) shows the state of the A-A section of Fig. 3(b), and Fig. 4(b-1) shows the state of the corresponding B-B section of Fig. 3(b).

However, if the focus ring FR is worn out by plasma processing such as etching, the height of the sheath of the focus ring FR becomes lower than the height of the sheath of the wafer W. In this way, the etching rate at the edge of the wafer W will increase rapidly, or the etching shape will be tilted. The so-called inclination of the etched shape means that due to the loss of the focus ring, the sheath is inclined at the edge of the wafer W, causing ions to be introduced into the wafer W from an oblique direction, so that the etched shape cannot be vertical and becomes inclined.

In view of this, in this embodiment, as long as the focus ring FR wears out, the central focus ring 38m is pushed up so much that the height of the wafer W and the sheath on the focus ring FR is equal. Accordingly, it is possible to prevent the etching rate at the edge of the wafer W from increasing rapidly, or the etched shape from tilting.

When controlling the displacement amount in the vertical direction of the piezoelectric actuator 101 so as to become a component (distance) corresponding to the loss amount of the focus ring FR, the distance corresponding to the loss amount of the central focus ring 38m is as long as it is relative to the central focus ring The loss of 38m can be in the range of 1 to 1.5 times. For example, the height of the central focus ring 38m during wafer W processing can be the same as the height of the inner focus ring 38i and the outer focus ring 38o, or at most 1.5 times higher than the loss of the central focus ring 38m. The moving mechanism 200 pushes up the central focus ring 38m by a predetermined amount with a resolution of 0.006mm.

For example, if the loss of the central focus ring 38m is controlled to be doubled, if the loss of the focus ring FR is 1.0mm, the height corresponding to the loss of the central focus ring 38m will be 1.0 mm. Therefore, in this case, the control unit 74 positions the piezoelectric actuator 101 so as to move the center focus ring 38m upward by 1.0 mm. As a result, as shown in FIGS. 4(a-2) and (b-2), the central focus ring 38m moves upward by 1.0 mm.

In this embodiment, if the focus ring FR is a new product, the thickness of each part of the focus ring FR, as shown in FIG. .

The central focus ring 38m has a thickness of 3.9 mm at the thickest part at the center, a thickness of 2.5 mm at the inner peripheral side, and a thickness of 1.6 mm at the outer peripheral side. The thickness of the outer focus ring 38o is 2.9mm (=1.3mm+1.6mm), and the thickness of the portion having the concave portion 138 is 1.3mm.

The upper limit value of the moving distance of the central focus ring 38m depends on the stroke of the moving mechanism 200. In this embodiment, the stroke of the moving mechanism 200 is 0.9 mm. Therefore, even if the loss of the focus ring FR reaches 0.9 mm, the same etching characteristics as a new product can be obtained for the focus ring FR by moving the moving mechanism 200 to the upper limit value.

The lower limit of the moving distance of the central focus ring 38m is the resolution of the piezoelectric actuator 101, that is, 0.006mm. That is to say, when the loss of the central focus ring 38m exceeds 0.006mm, the control unit 74 of this embodiment moves the central focus ring 38m upward by a distance corresponding to the loss in units of 0.006mm. When the moving distance of the central focus ring 38m reaches more than 0.9mm, the control unit 74 will control to prompt the replacement of the focus ring FR. However, the upper limit value of the movement distance of the central focus ring 38m is not limited to 0.9 mm, and may be set to a value smaller than 0.9 mm.

(Size and Material) The size of the wafer W is 300mm. As shown in FIG. 5, the outer diameter of the inner focus ring 38i of this embodiment is 309 mm. The inner diameter of the annular portion 38m1 of the central focus ring 38m in this embodiment is 302mm, and the outer diameter is 316mm. In this embodiment, the outer diameter of the outer focus ring 38o is 360mm.

However, the respective outer diameters of the inner focus ring 38i, the central focus ring 38m, and the outer focus ring 38o are not limited to the above-mentioned dimensions. For example, the outer diameter of the inner focus ring 38 i may be larger than the outer diameter of the wafer W by 2.5% to 3.5%. Furthermore, the outer diameter of the central focus ring of 38 m may be larger than the outer diameter of the wafer W by 4.5% to 5.5%. Furthermore, the outer diameter of the outer focus ring 38 o may be larger than the outer diameter of the wafer W by 19.5% to 20.5%.

The respective materials of the inner focus ring 38i, the central focus ring 38m, and the outer focus ring 38o are formed of any one of Si (silicon), SiO ₂ (silicon dioxide), and SiC (silicon carbide). The materials of the inner focus ring 38i, the central focus ring 38m, and the outer focus ring 38o may be the same or different.

However, the material of the central focus ring 38m is preferably harder than the material of the inner focus ring 38i and the outer focus ring 38o. For example, if the material of the central focus ring 38m is less prone to wear and tear during processing by using _SiO2 or SiC, which is less prone to loss than Si, the etching rate is less likely to change, and the focus ring FR can be extended. of life.

For example, it is preferable that the respective material of the inner focus ring 38i and the outer focus ring 38o is Si, and the material of the central focus ring 38m is SiO ₂ or SiC.

[Results of Etching Rate of Three-Divided Focus Ring] Next, referring to FIG. 6 and FIG. 7, an example of the etching rate in the case of using the three-divided focus ring FR of this embodiment is compared with the comparative example, while explaining. In FIG. 6, FIG. 6(c) shows an example of the etching rate of the focus ring FR of this embodiment, and FIG. 6(a) and (b) show an example of the etching rate of the focus rings FR1 and FR2 of the comparative example. In the diagram in Fig. 7, Fig. 7(c) is for the focus ring FR of this embodiment, and Fig. 7(a) and (b) are for the focus rings FR1 and FR2 of the comparative example, to illustrate the generation of plasma .

The focus ring FR1 (Standard FR1) of the comparative example in Fig. 6(a), as shown in the hardware structure (HW) and Condition (condition), is an undivided one-piece focus ring. The focus ring FR2 (2pieces FR2) of the comparative example in (b) is a focus ring divided into two parts. The focus ring FR (3pieces FR) of the present embodiment of (c) is a focus ring divided into three parts.

As shown in Condition, between the focus ring FR1 and the electrostatic chuck 36 of the comparative example in FIG.

No polymer flake exists between the focus ring FR2 of the comparative example in FIG. 6( b ) and the focus ring FR of the present embodiment in FIG. 6( c ) and the electrostatic chuck 36 . However, if the polymer sheet is interposed between the inner focus ring 38i and the outer focus ring 38o of the focus ring FR of the present embodiment in FIG. The heat conduction between 36 is therefore better.

As shown in ER (etching rate), in any case of Figure 6(a)~(c), when the focus ring is a new product (that is, the POR of Figure 6(a), Figure 6(b) and (c) The etching rate at 0 mmUp is uniform throughout the entire surface of the wafer W.

On the other hand, in the case of using the focus ring FR1 of the comparative example in FIG. Soaring high. Therefore, it can be seen that at the edge of the wafer W, the etching rate cannot be controlled.

Furthermore, in the focus ring FR2 of the comparative example in FIG. 6( b ), the inner focus ring is fixed, and only the outer focus ring moves up and down. In this case, the sharp increase of the etching rate at the edge is suppressed, and the edge of the wafer W can be controlled more than the focus ring FR1 of the comparative example shown in FIG. 6( a ). However, as the height of the outer focus ring increases from 0mm to 1mm, 2mm, the offset of the overall etch rate in the wafer W plane becomes larger.

On the other hand, in the focus ring FR of this embodiment shown in FIG. 6(c), the inner focus ring 38i and the outer focus ring 38o are fixed, and only the center focus ring 38m moves up and down. Thereby, the edge of the wafer W is controlled, and the increase of the etching rate at the edge is further suppressed. Furthermore, even if the height of the central focus ring 38m is increased from 0mm to 1mm or 2mm, the overall etching rate in the wafer W plane does not change.

For the graphs in the middle of FIG. 6 of the comparative example and the present embodiment, please refer to the graph at the bottom of FIG. The ER% in the bottom graph is obtained by calculating ER(x)/ER(Center)×100. x represents the radius of wafer W. In the graph at the bottom of FIG. 6 , in the case of using the focus ring FR1 of the comparative example in FIG. 6( a ), the etching rate at the edge of the wafer W could not be controlled. In the case of using the focus ring FR2 of the comparative example in FIG. 6( b ), the etching rate of the edge portion of the wafer W can be controlled. Similarly, in the case of using the focus ring FR of this embodiment shown in FIG. 6( c ), the etching rate at the edge of the wafer W can be controlled. However, if the focus ring FR2 divided into two parts in FIG. 6( b ) is used, the etching rate becomes higher in the middle section of the wafer W, so the overall etching characteristics are changed. On the other hand, with the three-part focus ring FR of this embodiment shown in FIG. 6( c ), the etching rate at the edge of the wafer W can be controlled without changing the overall etching characteristics.

As a conclusion, if the focus ring FR of this embodiment shown in Fig. 6(c) is used, the moving distance of the central focus ring 38m will be increased according to the loss of the central focus ring 38m. Thereby, on the one hand, the etching property of the entire in-plane of the wafer W can be maintained, and on the other hand, the etching rate of the edge portion of the wafer W can be controlled. Furthermore, it is possible to suppress the problem that the etched shape is inclined at the edge of the wafer W.

With this focus ring FR, by moving the center focus ring 38m up and down according to the wear amount of the center focus ring 38m, the loss of the focus ring FR can be compensated, and the life of the focus ring FR can be extended.

Next, the operation of the focus ring FR and the generation of plasma in this embodiment will be described with reference to FIG. 7 . Columns (a) and (b) of FIG. 7 schematically illustrate the mechanism of plasma generation when the focus rings FR1 and FR2 of the comparative example are used.

"RF Path" in FIG. 7 represents the flow of high-frequency RF power between the electrostatic chuck 36 and the focus rings FR, FR1, and FR2. In the case of using the focus ring FR1 of the comparative example, when the sheath is flat, the high-frequency HF power for generating plasma output from the first high-frequency power supply 57 will be on the central electrostatic chuck 36 side and On the outer focus ring FR1 side, almost the same level of current flows, and plasma is generated in the plasma generation space S. The etching characteristic of the generated plasma causes a sharp increase in the etching rate at the edge of the wafer W as the focus ring FR1 wears out.

In the case of using the focusing ring FR2 of the comparative example, as shown in column (b) of FIG. There is even more current on the FR1 side of the ring. The reason for this is explained below.

Below the outer focus ring that is pushed up, a space U1 is created. Due to the application of high-frequency RF power, electrostatic capacitance is generated in the space U1. The electrostatic capacitance generated in the space U1 suppresses the flow of current on the focus ring side. Therefore, current flows more easily on the side of the electrostatic chuck 36 than on the side of the focus ring. Therefore, compared with the case of the focus ring FR1 shown in FIG. 7(a), more current will flow to the side of the electrostatic chuck 36, and the plasma generated in the plasma generation space S will have a plasma density in the center higher. Accordingly, in the focus ring FR2 , the more the outer focus ring is raised, the higher the etching rate in the entire surface of the wafer W is.

On the other hand, in the focus ring FR of the present embodiment, as shown in FIG. The current of the focus ring FR1 will be almost the same.

This is because in the focus ring FR of this embodiment, the focus ring FR is divided into three parts, and only the central focus ring 38m moves up and down, so that when the center focus ring 38m is pushed up near the edge of the wafer W, What is formed is the minimum space U2. Thereby, the electrostatic capacitance generated in the space U2 can be minimized, and the currents flowing to the electrostatic chuck 36 side and the focus ring FR1 side can be made to the same level. Thereby, in this embodiment, the height of the focus ring FR and the sheath of the electrostatic chuck 36 can be matched by pushing up the central focus ring 38m without causing the overall etching rate deviation in the wafer W plane. In this way, the etching rate of the edge portion of the wafer W can be controlled.

As described above, with the three-part focus ring FR of this embodiment, only the central focus ring 38m moves up and down. Thereby, the etching characteristics of the edge portion of the wafer W can be controlled without changing the etching characteristics of the plasma treatment in the entire wafer W plane. Thereby, it is possible to suppress, for example, a sharp rise in the etching rate at the edge of the wafer W, or an inclination of the etched shape. (Focus Ring FR of Modified Example) Next, the focus ring FR, the moving mechanism 200 , and the driving unit of the modified example will be described with reference to FIG. 8 . In this modified example, the piezoelectric actuator 101 is also used as an example of the drive unit, but it is not limited thereto. Compared with the moving mechanism 200 of the embodiment shown in FIG. 2, the moving mechanism 200 of this modified example shown in FIG. 8 is simplified, and the length in the diameter direction of the central focus ring 38m is shortened. The work table 12 is supported by a conductive cylindrical support portion 16 extending vertically upward from the bottom of the processing chamber 10 , and a housing 100 provided adjacent to the inside thereof. In this modified example, the moving mechanism 200 is disposed on the lower side of the electrostatic chuck 36 and not disposed on the outer peripheral side of the electrostatic chuck 36 . Specifically, the electrostatic chuck 36 and the work table 12 are provided so that the through hole 36 c and the through hole 12 a communicate with each other. The pinhole of the ejector pin 102 is provided with an O-ring 110 for dividing the vacuum space and the atmospheric space. The ejector pin 102 penetrates the through-hole 12a and the through-hole 36c, and the front end part abuts the bottom surface of the center focus ring 38m, and is connected with the center focus ring 38m. The base end portion of the ejector pin 102 is fitted to the member 104a. The upper end of the piezoelectric actuator 101 is fixed to the member 104a with a screw 104c; the lower end of the piezoelectric actuator 101 is fixed to the member 104b with a screw 104d. Thereby, the piezoelectric actuator 101 is in contact with the ejector pin 102 and the center focus ring 38m via the member 104a. With this structure, the ejector pin 102 moves up and down according to the displacement amount of the piezoelectric actuator 101 in the up and down direction. In this way, the central focus ring 38m will only move by a predetermined height with 0.006mm as the smallest unit. In this modified example, a predetermined space is provided between the top surface of the electrostatic chuck 36 and the bottom surface of the central focus ring 38m. In this way, the central focus ring 38m can not only move upward, but also move downward by a predetermined height in a predetermined space. In this modified example, the moving mechanism 200 is disposed more inward than the outer peripheral ends of the electrostatic chuck 36 and the workpiece table 12 , and the ejector pin 102 penetrates the interior of the workpiece table 12 and the electrostatic chuck 36 . Thereby, the ejector pin 102 can lift up the center focus ring 38m from directly below, and can move it up and down. Furthermore, with this structure, the central focus ring 38m of this modified example can shorten the length in the diameter direction compared to the central focus ring 38m of the embodiment shown in FIG. 2 . Similarly, by arranging the ejector pin 102 inwardly from the outer peripheral end of the electrostatic chuck 36 and the work table 12, the length in the diameter direction of the member 104a can be shortened. Thereby, the deflection of the central focus ring 38m and the deflection of the member 104a can be minimized, and the positional accuracy of the central focus ring 38m in the height direction can be improved. As a result, the heights of the sheath on the wafer W and the sheath on the focus ring FR can be more accurately aligned, the uniformity of the etching rate over the entire surface of the wafer W can be improved, and tilting can be prevented. Furthermore, in the moving mechanism 200 of this modified example, the housing 100, the bearing portion 105, the connecting portion 103, etc. contained in the moving mechanism 200 of the embodiment in FIG. cost. Furthermore, with the focus ring FR of this modified example, by providing a predetermined space under the center focus ring 38m, the structure that the center focus ring 38m can move not only upward but also downward is formed. Therefore, the lower limit value of the moving distance of the central focus ring 38m is the resolution of the piezoelectric actuator 101, as in the embodiment of FIG. 2 . On the other hand, the upper limit value of the moving distance of the central focus ring 38m is smaller than the height of the predetermined space between the top surface of the electrostatic chuck 36 and the bottom surface of the central focus ring 38m and the thickness of the central focus ring 38m. "The numerical value obtained by adding. In this way, the central focusing ring 38m can not only move upward, but also downward, thereby expanding the control range of the sheath. Furthermore, according to the focus ring FR of this modified example, compared with the focus ring FR of the embodiment shown in FIG. 2 , the length in the diameter direction is shortened, and the length of the claw portion 38m2 is shortened. Thereby, the singularity of the electrostatic capacitance caused by the protruding structure of the claw portion 38m2 becomes smaller, and the adverse effect on the etching characteristics disappears or becomes smaller, so the uniformity of the etching rate can be further improved. In addition, in the above-mentioned embodiment and modified example, the height of the peak of the top surface of the central focus ring 38m during processing may be the same as or higher than the height of the peaks of the top surface of the inner focus ring 38i and the outer focus ring 38o. .

As mentioned above, although the substrate processing apparatus was demonstrated based on the said embodiment, the substrate processing apparatus of this invention is not limited to the said embodiment, Various deformation|transformation and improvement are possible within the range of this invention. Items described in the plural embodiments described above can be combined within a range that does not conflict with each other.

For example, although the high-frequency electric power RF was applied in the said embodiment, it is not limited to this, You may apply a direct current (DC).

Furthermore, the present invention is applicable not only to the parallel plate type dual-frequency application device shown in FIG. 1 , but also to other substrate processing devices. As for substrate processing equipment, it is possible to use: capacitively coupled plasma (CCP: Capacitively Coupled Plasma) equipment, inductively coupled plasma (ICP: Inductively Coupled Plasma) processing equipment, plasma processing using radial line slot antenna device, Helicon Wave Plasma (HWP: Helicon Wave Plasma) device, Electron Cyclotron Resonance Plasma (ECR: Electron Cyclotron Resonance Plasma) device, surface wave plasma processing device, etc.

Furthermore, the substrate processing device may also be a device that performs predetermined processing such as heat treatment on the substrate without generating plasma. The substrate processing apparatus may or may not have an electrostatic chuck 36 .

In addition, in this specification, the semiconductor wafer W is demonstrated as an example of a to-be-processed object. However, the object to be processed is not limited thereto, and may be used for various substrates of LCD (Liquid Crystal Display) and FPD (Flat Panel Display), photomasks, CD substrates, printed substrates, and the like.

5‧‧‧substrate processing device 10‧‧‧processing chamber 12‧‧‧work table 12a‧‧‧through hole 16‧‧‧conductive cylindrical support part 16a‧‧‧space 18‧‧‧exhaust path 20‧‧ ‧Baffle plate 22‧‧‧Exhaust port 24‧‧‧Exhaust pipe 26‧‧‧Exhaust device 27‧‧‧Inlet outlet 28‧‧‧Gate valve 30‧‧‧Second high frequency power supply 32‧‧‧Matching Device 34‧‧‧Power supply rod 36‧‧‧Electrostatic chuck 36a‧‧‧Electrode 36b‧‧‧Insulating film 36c‧‧‧Through hole 38i‧‧‧Inner focus ring 38m‧‧‧Central focus ring 38m1‧‧‧Ring Part 38m2‧‧‧Claw part 38o‧‧‧Outer focus ring 40‧‧‧DC power supply 42‧‧‧Switch 43‧‧‧Wrapped wire 44‧‧‧Refrigerant flow path 46, 48‧‧‧Piping 50‧‧‧Gas Supply pipe 51‧‧‧jet head 52‧‧‧gas supply hole 54‧‧‧sealing ring 56‧‧‧gas inlet 57‧‧‧first high-frequency power supply 58‧‧‧diffusion chamber 59‧‧‧matching device 60 ‧‧‧Power line 66‧‧‧gas supply source 74‧‧‧control part 100‧‧‧casing 100a‧‧‧recess 101‧‧‧piezoelectric actuator 102‧‧‧push pin 103‧‧‧link Parts 104a, 104b‧‧‧members 104c, 104d‧‧‧screw 105‧‧‧bearing part 105a‧‧‧recess 111, 110‧‧‧ring 136‧‧‧molecule sheet 138‧‧‧recess 200‧‧‧moving mechanism Cw‧‧‧cooling water FR, FR1, FR2‧‧‧focus ring LF, HF‧‧‧high frequency U1, U2‧‧‧space W‧‧‧wafer

[ Fig. 1 ] A diagram showing an example of a substrate processing apparatus according to an embodiment. [FIG. 2] A diagram showing an example of a focus ring, a moving mechanism, and a drive unit according to an embodiment. [Fig. 3] Perspective view, plan view and cross-sectional view of the focus ring divided into three parts in one embodiment (a) to (d). [FIG. 4] (a-1), (a-2), (b-1), (b-2) are diagrams for explaining the up and down movement of the focus ring in one embodiment. [ Fig. 5 ] A diagram illustrating a diameter of a focus ring according to an embodiment. [FIG. 6] (a)-(c) are graphs showing an example of the etching rate of the focus ring of an embodiment and a comparative example. [FIG. 7] (a)-(c) are diagrams illustrating generation of plasma by the focus ring of an embodiment and a comparative example. [FIG. 8] A diagram showing an example of a focus ring, a moving mechanism, and a drive unit according to a modified example.

12‧‧‧Workpiece table

16‧‧‧Conductive cylindrical support part

16a‧‧‧space

36‧‧‧Electrostatic chuck

38i‧‧‧Inner focus ring

38m‧‧‧Central focus ring

38m1‧‧‧ring part

38m2‧‧‧Claw

38o‧‧‧outer focus ring

100‧‧‧shell

102‧‧‧Push pin

103‧‧‧Connection Department

138‧‧‧Concave

W‧‧‧Wafer

Claims (21)

A substrate processing device has a focus ring; the focus ring includes: an inner focus ring, which is arranged near a substrate, and the substrate is placed on a substrate holding platform in a processing chamber; a central focus ring, which is arranged outside the inner focus ring, and It can move up and down by a moving mechanism; and the outer focus ring is arranged on the outside of the central focus ring; The bottom surface of the ring is provided with a recess for accommodating the claw, and the moving mechanism moves the claw up and down. In the substrate processing apparatus according to claim 1 of the patent scope, the moving mechanism moves the central focus ring to a height corresponding to the loss of the central focus ring. The substrate processing device as claimed in claim 1 or 2 of the scope of the patent application, wherein the moving mechanism includes an ejector pin, and the ejector pin is arranged directly under the claw, and the front end of the ejector pin Connect to the bottom surface of the claw to raise the claw. The substrate processing device as claimed in item 3 of the scope of the patent application, wherein the substrate holding table has a work table and an electrostatic chuck arranged on the top surface of the work table, and the ejector pin is arranged on a lower side than the electrostatic chuck and the work table The outer peripheral end is more inwardly biased, The ejector pin penetrates the electrostatic chuck and the workpiece table. The substrate processing apparatus according to claim 1 or 2 of the scope of the patent application, wherein the moving mechanism includes ejector pins, and the ejector pins are arranged on the outer side of the outer peripheral end of the outer focus ring. The front end portion of the pin abuts against the bottom surface of the connecting portion connected to the claw to raise the claw. The substrate processing device according to claim 5 of the scope of the patent application, wherein the substrate holding table has a workpiece table and an electrostatic chuck arranged on the top surface of the workpiece table, and the ejector pin is arranged at the outer peripheral end of the electrostatic chuck The ejector pin is positioned more outwardly and inwardly than the outer peripheral end of the work table, and penetrates the inside of the work table. The substrate processing device according to claim 1 or 2 of the scope of the patent application further includes: a casing arranged around the substrate holding table and provided with the moving mechanism; Drive the moving mechanism. The substrate processing apparatus according to claim 7 of the patent application, wherein the plurality of driving parts are connected to each other by a component, and are installed in the casing through the component. Such as the substrate processing device of item 7 of the scope of the patent application, wherein, The lower limit of the moving distance of the central focus ring is the resolution of the driving unit; the upper limit of the moving distance of the central focus ring is a value smaller than the thickness of the central focus ring. For example, the substrate processing device in claim 1 or 2 of the scope of the patent application further has: a plurality of driving parts driving the moving mechanism up and down; a plurality of the driving parts are connected to each other by components, and the moving mechanism is connected through the components . For example, the substrate processing device of item 10 of the scope of the patent application, wherein, the lower limit value of the moving distance of the central focus ring is the resolution of the driving part; the value of the upper limit value of the moving distance of the central focus ring is less than The value obtained by adding the height of the predetermined space between the top surface of the substrate holding platform and the bottom surface of the central focus ring to the thickness of the central focus ring. In the substrate processing device as claimed in claim 3 of the scope of the patent application, the ejector pin is formed of sapphire. In the substrate processing apparatus according to claim 4 of the scope of the patent application, a predetermined space is provided between the top surface of the electrostatic chuck and the bottom surface of the central focus ring. The substrate processing apparatus according to claim 10 of the patent application, wherein the drive unit is a piezoelectric actuator. The substrate processing apparatus according to claim 1 or 2 of the patent application, wherein the height of the peak of the top surface of the central focus ring during processing in the processing chamber is higher than the top surfaces of the inner focus ring and the outer focus ring of the peak. The substrate processing apparatus according to claim 1 or 2 of the patent application, wherein the inner focus ring, the central focus ring and the outer focus ring are each formed of the same material or different materials. As for the substrate processing device in claim 1 or 2 of the patent application, wherein the material of the inner focus ring, the central focus ring and the outer focus ring is any one of silicon, silicon dioxide, and silicon carbide. The substrate processing apparatus according to claim 1 or 2 of the patent claims, wherein the central focus ring is formed of a harder material than the material of the inner focus ring and the outer focus ring. For example, the substrate processing device of claim 1 or 2 of the patent scope, wherein the outer diameter of the inner focus ring is 2.5% to 3.5% larger than the outer diameter of the substrate. Such as the substrate processing device of claim 1 or 2 of the patent scope, wherein the outer diameter of the central focus ring is 4.5% to 5.5% larger than the outer diameter of the substrate. For example, the substrate processing device of claim 1 or 2 of the patent scope, wherein the outer diameter of the outer focus ring is 19.5% to 20.5% larger than the outer diameter of the substrate.

Images