Plasma processing apparatus

Abstract

This invention provides a plasma processing apparatus capable of fine-tuning the conduction of exhaust gas and enabling high-precision pressure control within the processing chamber. The plasma processing apparatus includes: a processing chamber; a base plate having an exhaust opening connected to the processing chamber; an exhaust cover disposed within the processing chamber opposite to the exhaust opening; an exhaust device for discharging gas from the processing chamber via the exhaust opening; and an actuator driving the exhaust cover, wherein the axis of the exhaust opening is aligned with the central axis of the processing chamber, the exhaust cover has a circular plate portion and a convex portion protruding from the circular plate portion toward the exhaust opening, and the exhaust cover is driven by the actuator to move to any one of the following positions: a first position where the convex portion is separated from the exhaust opening in the axial direction; a second position where the axial position of the convex portion overlaps with the axial position of the exhaust opening; and a third position where the circular plate portion abuts against the base plate.

Description

Technical Field

[0001] This invention relates to plasma processing apparatus. Background Technology

[0002] In plasma processing apparatuses that process samples such as semiconductor wafers, achieving fine and high-precision processing requires the formation of higher density and more uniform plasma within the processing chamber. To stably form this high-density plasma, it is crucial to stabilize the pressure within the processing chamber of the vacuum vessel at a higher vacuum level (lower pressure).

[0003] In conventional plasma processing equipment, a vacuum pump or other exhaust device is connected to the processing chamber located inside a vacuum container in order to remove particles such as gases, plasma, or byproducts generated during the processing.

[0004] Furthermore, an adjustment device is installed on the exhaust passage leading from the processing chamber to the inlet of the vacuum pump to adjust the exhaust volume per unit time, and the exhaust volume of gas and particles inside the processing chamber is adjusted by the adjustment device, thereby adjusting the internal pressure of the processing chamber for plasma formation.

[0005] More specifically, in conventional plasma processing devices, the passage connecting the exhaust port at the bottom of the processing chamber inside the vacuum container to the inlet of the vacuum pump is equipped with an adjustment mechanism that regulates the resistance and ease of flow (conduction) of the gas discharged from the exhaust port to the inlet, thereby adjusting the amount of gas discharged from the vacuum container and regulating the pressure inside the vacuum container.

[0006] As a regulating mechanism for adjusting the resistance and ease of flow, valves have been developed that change the size and area of ​​the openings of passages, inlets, or outlets. Valves are known to adjust the size and area of ​​the openings by rotating such valves or moving them in the direction of the axis of the cross-section of the pipeline.

[0007] For example, an example of such a valve is disclosed in Patent Document 1. In this prior art, a gate valve capable of sliding opening and closing is provided to adjust the resistance and ease of flow of gas through the gate. The area of ​​the gate through which gas passes can be variably adjusted using the gate valve, and the internal pressure of the vacuum container can be adjusted.

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent Application Publication No. 2012-054491

[0011] Patent Document 2: Japanese Patent Application Publication No. 2017-010624 Summary of the Invention

[0012] The problem that the invention aims to solve

[0013] However, in the technology of the aforementioned Patent Document 1, when performing high-precision pressure control in a higher pressure area of ​​the processing room, it is difficult to adjust the gate valve between a closed state and a slightly open state (called an extremely low opening). Therefore, the transmission difference of the exhaust volume is prone to increase, resulting in a problem of reduced pressure control accuracy.

[0014] In contrast, Patent Document 2 discloses a structure in which an O-ring is provided on an exhaust cover that is configured to be raised and lowered freely using a lifter. The exhaust cover is pressed against the base plate through the O-ring, thereby blocking the flow of gas through the base plate and separating the exhaust cover from the base plate, thus allowing the flow of gas through the base plate.

[0015] According to the technology in Patent Document 2, a groove with a diameter larger than the cylindrical exhaust opening of the base plate is provided in the exhaust cover, and an O-ring is embedded in the groove. Therefore, by bringing the base plate into contact with the O-ring with an opening of 0, the conduction becomes 0, thus enabling the vacuum container to be sealed.

[0016] However, according to the technology in Patent Document 2, the consideration of the next point is insufficient, thus causing problems.

[0017] If pressure control is required for a vacuum container in a high-pressure area, the distance between the base plate and the O-ring embedded in the exhaust cover needs to be adjusted slightly to regulate the transmission of exhaust volume. Therefore, the exhaust cover requires control at extremely low opening degrees. However, the transmission of exhaust volume at extremely low opening degrees largely depends on the protrusion allowance (the amount of protrusion from the groove edge) of the O-ring embedded in the cover. Even at the same opening degree, the protrusion allowance of the O-ring differs between chambers, and the corresponding difference in transmission becomes a significant factor in mechanical error.

[0018] Furthermore, the transmission of exhaust volume at extremely low opening also depends on the flattening of the O-ring seal, thus there is a problem of increased pressure control deviation due to mechanical errors.

[0019] The purpose of this invention is to provide a plasma processing device that can finely adjust the conduction of exhaust gas and achieve high-precision pressure control within the processing chamber.

[0020] Solution for solving the problem

[0021] To achieve the above objectives, one representative plasma processing apparatus of the present invention is implemented by the following plasma processing apparatus:

[0022] The plasma processing apparatus includes: a processing chamber; a base plate having an exhaust opening connected to the processing chamber; an exhaust cover disposed inside the processing chamber opposite to the exhaust opening; an exhaust device for discharging gas from the processing chamber via the exhaust opening; and an actuator for driving the exhaust cover.

[0023] in,

[0024] The axis of the exhaust opening is aligned with the central axis of the processing chamber.

[0025] The exhaust cover has a circular plate portion and a convex portion protruding from the circular plate portion toward the exhaust opening side.

[0026] The exhaust cover is driven by the actuator to move to any one of the following positions: a first position where the convex portion is separated from the exhaust opening in the axial direction; a second position where the axial position of the convex portion overlaps with the axial position of the exhaust opening; and a third position where the circular plate portion abuts against the base plate.

[0027] Invention Effects

[0028] According to the present invention, a plasma processing apparatus is provided that can finely adjust the conduction of exhaust gas and can perform pressure control in the processing chamber with high precision.

[0029] Other issues, structures, and effects not mentioned above will be clarified through the following description of implementation methods. Attached Figure Description

[0030] Figure 1 This is a longitudinal sectional view showing the overall structure of the plasma processing apparatus according to an embodiment of the present invention.

[0031] Figure 2 This is an illustrative representation of an embodiment of the present invention. Figure 1 A longitudinal sectional view of the lower part of the vacuum processing section.

[0032] Figure 3 This is an illustrative representation of the present embodiment. Figure 2 A three-dimensional view of the exhaust cover.

[0033] Figure 4 This is an illustrative representation of the present embodiment. Figure 2 A three-dimensional view of the exhaust cover.

[0034] Figure 5 This is a longitudinal sectional view schematically showing the positional relationship between the exhaust cover and the base plate having an exhaust opening in this embodiment, and it shows the first position.

[0035] Figure 6This is a longitudinal sectional view schematically showing the positional relationship between the exhaust cover and the base plate with the exhaust opening in this embodiment, and it shows the second position.

[0036] Figure 7 This is a longitudinal sectional view schematically showing the positional relationship between the exhaust cover and the base plate with the exhaust opening in this embodiment, and it indicates the third position. Detailed Implementation

[0037] The embodiments of the present invention will now be described using the accompanying drawings.

[0038] Figure 1 This is a longitudinal sectional view schematically showing the overall structure of the plasma processing apparatus of this embodiment.

[0039] Figure 1 The plasma processing apparatus 100 of this embodiment shown includes an electromagnetic wave supply unit 101 and a vacuum processing unit 102. The electromagnetic wave supply unit 101 is a part that generates plasma by utilizing the interaction of an electric field and a magnetic field through electron cyclotron resonance (ECR). The vacuum processing unit 102 is a part that uses plasma and a specific gas under reduced pressure to etch samples such as wafers.

[0040] The electromagnetic wave supply unit 101 includes a high-frequency power supply 201 for generating an electric field for plasma generation and a solenoid coil 202 for generating a magnetic field. Under the action of the electric and magnetic fields, particles such as atoms or molecules of the processing gas supplied to the upper part of the circular-plate-shaped shower plate 204 disposed inside the cylindrical discharge block unit 203 are excited, causing them to ionize or deflect and generate plasma. Using this plasma, a film structure including a mask pre-formed on the upper surface of a substrate-shaped sample such as a semiconductor wafer 206 disposed in the processing chamber and a film layer of the object to be processed is etched.

[0041] The vacuum processing unit 102 includes: a vacuum container comprising an upper container 205 and a lower container 209 enclosing a processing chamber for plasma formation; and an exhaust pump (exhaust device) 213 comprising a vacuum pump such as a turbomolecular pump disposed below the vacuum container. A stage 207 for mounting wafers 206 is disposed inside the processing chamber. The outer surfaces of the upper container 205 and the lower container 209 are exposed to the atmosphere surrounding the vacuum processing unit 102, and the vacuum container including the upper container 205 and the lower container 209 constitutes a vacuum partition that hermetically separates the internal processing chamber from the external atmosphere.

[0042] Below the vacuum container of the vacuum processing unit 102, a base plate 210 with an exhaust opening 215 for discharging gas and plasma particles from the processing chamber is supported by a support column 212. Connected to the exhaust pump 213, the circular exhaust opening 215 is positioned directly below the worktable 207, and the axis of the exhaust opening 215 is aligned with or nearly aligned with the central axis 214 of the processing chamber. This is represented here as the axis of the exhaust opening 215 being aligned with the central axis 214 of the processing chamber.

[0043] Next, use Figures 2 to 3 The pressure control of the vacuum processing unit 102 in this embodiment will be explained. Figure 2 It is shown schematically. Figure 1 A longitudinal sectional view of the lower part of the vacuum processing unit 102 shown. Figure 3 This is a three-dimensional view of the exhaust cover 208 taken from above.

[0044] exist Figure 2 In this configuration, an exhaust cover 208, which has a generally circular plate shape, is positioned above the exhaust opening 215. For example... Figure 3 As shown, the exhaust cover 208 has: a circular plate portion 208a; and a pair of arm portions 208b that extend radially outward from the outer periphery of the circular plate portion 208a. Figure 3 The two parts are: a central part (in the left-right direction) and a convex part 208c, which is formed by protruding downwards from the circular plate part 208a and is cylindrical with a smaller diameter than the circular plate part 208a.

[0045] Arms 208b are connected to telescopic shafts arranged vertically along the actuator 211. The telescopic shafts extend and retract by supplying power to the actuator 211 from the outside. The extension and retraction of the telescopic shafts, driven by the arms 208b, causes the exhaust cover 208 to move up and down, thereby changing the distance of the exhaust opening 215. This adjusts the conduction of exhaust gas from the processing chamber.

[0046] In the processing of wafer 206, the flow rate or speed of internal gas, plasma, and products discharged to the outside of the processing chamber is adjusted by using the value of this conduction and the exhaust volume per unit time of exhaust pump 213, and the pressure of the processing chamber is adjusted to the desired vacuum level by balancing the exhaust and the supply of processing gas.

[0047] Figure 4 This is a perspective view taken from the lower exhaust cover 208. An O-ring groove 208d is formed on the lower surface of the circular plate portion 208a at a position radially outward from the convex portion 208c.

[0048] Reference Figure 5A cone-shaped downward chamfered portion 208e is formed on the lower outer periphery of the convex portion 208c, and an upward chamfered portion 215a is formed on the upper inner periphery of the vent opening 215 of the base plate 210, opposite to it. (See reference...) Figure 6 The outer diameter of the convex part 208c is set as d1, and the inner diameter of the exhaust opening 215 is set as d2.

[0049] The position of the exhaust cover 208 when the telescopic shaft of the actuator 211 is driven in stages along the vertical direction is... Figure 5 , Figure 6 , Figure 7 The image is shown schematically, but the arm portion is omitted.

[0050] Figure 5 The diagram shows the exhaust cover 208 with its lower end of the protrusion 208c separated from the upper surface of the base plate 210 in the axial direction, and this position of the exhaust cover 208 is designated as the first position. In the first position, the transmission of exhaust volume depends on the distance D1 between the lower end of the protrusion 208c of the exhaust cover 208 and the upper surface of the base plate 210. This transmission is the same even when the exhaust cover 208 does not have the protrusion 208c.

[0051] Figure 6 The diagram shows the exhaust cover 208 with its protrusion 208c inserted into the exhaust opening 215 of the base plate 210, overlapping in the axial direction. This position of the exhaust cover 208 is designated as the second position. In this second position, the distance ((d1-d2) / 2) between the outer diameter of the protrusion 208c and the inner diameter of the exhaust opening 215 is smaller than the distance D2 between the upper surface of the base plate 210 and the lower end of the O-ring 305 mounted on the exhaust cover 208. In this case, the transmission of exhaust volume depends on the difference (d1-d2) between the outer diameter of the protrusion 208c and the inner diameter of the exhaust opening 215.

[0052] With the convex portion 208c of the exhaust cover 208 inside the exhaust opening 215 of the base plate 210, if the telescopic shaft of the actuator 211 is moved up and down, the amount of overlap between the convex portion 208c and the exhaust opening 215 changes according to the relative position of the exhaust cover 208 and the base plate 210. As a result, the resistance of the gas passing through the annular space formed by the outer periphery of the convex portion 208c of the exhaust cover 208 and the inner periphery of the exhaust opening 215 changes slightly, thus enabling fine-tuning of the transmission.

[0053] The conduction depends on the shape of the protrusion 208c of the exhaust cover 208, and the conduction is smaller compared to, for example, an exhaust cover without a protrusion. Therefore, according to this embodiment, the vacuum processing unit 102 can be controlled with high precision in high-pressure areas.

[0054] Furthermore, by making the transmission of exhaust volume depend on the difference between the outer diameter of the convex portion 208c of the exhaust cover 208 and the inner diameter of the exhaust opening 215, the influence of mechanical errors such as the flattening amount of the O-ring seal 305 in the transmission can be eliminated, and the influence of mechanical tolerances of actuators 211 and the like with relatively small deviations can be limited.

[0055] Moreover, in Figure 6 In this state, the conduction is changed according to the dimensions of the downward chamfer 208e and the upward chamfer 215a. That is, by pre-setting the dimensions of the downward chamfer 208e and the upward chamfer 215a, the desired conduction characteristics can be obtained.

[0056] Figure 7 The image shows the exhaust cover 208 at its lowest point with the O-ring 305 tightly pressed against the base plate 210. This position of the exhaust cover 208 is designated as the third position. In the third position, the O-ring 305 is tightly pressed against the base plate 210, thus the transmission of exhaust volume becomes zero, and the flow of exhaust from the processing chamber to the exhaust opening 215 is blocked.

[0057] In the embodiments described above, the convex portion 208c is made into a solid cylindrical shape, but it can also be a hollow cylindrical shape. Alternatively, instead of making the exhaust opening 215 and the convex portion 208c cylindrical, they can also be made into a square cylindrical shape.

[0058] Alternatively, in the above embodiments, the height between the bottom surface of the circular plate portion 208a and the bottom surface of the circular plate portion 208c, more specifically, between the bottom surface of the circular plate portion 208a and the outer peripheral sidewall surface of the base (upper end in the figure) of the convex portion 208c, i.e., the height of the convex portion 208c, can be a value smaller than the height of the base plate 210 or the portion constituting the inner peripheral sidewall surrounding the exhaust opening 215. Alternatively, the height of the convex portion 208c can be a value smaller than the distance between the bottom surface of the outer peripheral portion of the circular plate portion 208a and the lower surface of the base plate 210 or the portion constituting the inner peripheral sidewall surrounding the exhaust opening 215 when the distance D2 between the O-ring 305 and the upper surface of the base plate 210 or the portion constituting the inner peripheral sidewall surrounding the exhaust opening 215 is equal to D1.

[0059] In this configuration, with the exhaust cover 208 moving downwards and the convex portion 208c entering the exhaust opening 215, the width (height) of the area where the inner peripheral sidewall of the exhaust opening 215 and the outer peripheral sidewall of the convex portion 208c overlap in the height direction increases uniformly until the O-ring 305 contacts the upper surface of the base plate 210 or the portion forming the inner peripheral sidewall surrounding the exhaust opening 215. The bottom surface of the convex portion 208c will not protrude downwards beyond the lower surface of the base plate 210 or the portion forming the inner peripheral sidewall surrounding the exhaust opening 215. This significantly reduces fluctuations in the height region of the exhaust cover 208 as it moves up and down within the exhaust opening 215, further improving the accuracy of exhaust volume adjustment.

[0060] Explanation of reference numerals in the attached figures

[0061] 100 Plasma Processing Unit

[0062] 101 Electromagnetic Wave Supply Department

[0063] 102 Vacuum Processing Department

[0064] 201 High-Frequency Power Supply

[0065] 202 Solenoid Coil

[0066] 203 Discharge Block Unit

[0067] 204 Cluster Plate

[0068] 205 upper container

[0069] 206 wafers

[0070] 207 Workbench

[0071] 208 Exhaust Cover

[0072] 208a Circular plate section

[0073] 208b Arm

[0074] 208c Convex part

[0075] 208d O-ring seal groove

[0076] 209 lower container

[0077] 210 base plate

[0078] 211 Actuator

[0079] 212 pillars

[0080] 213 Exhaust Pump

[0081] 214 Central Axis

[0082] 215 Exhaust opening

[0083] 305 O-ring seal.

Claims

1. A plasma processing apparatus comprising: a processing chamber; a base plate having an exhaust opening connected to the processing chamber; an exhaust cover disposed within the processing chamber opposite to the exhaust opening; an exhaust device for discharging gas from the processing chamber via the exhaust opening; and an actuator for driving the exhaust cover. The plasma processing device is characterized in that... The axis of the exhaust opening is aligned with the central axis of the processing chamber. The exhaust cover has a circular plate portion and a convex portion that protrudes downward toward the exhaust opening from the center of the lower surface of the circular plate portion. The exhaust cover is driven by the actuator to move vertically to any one of the following positions: a first position where the convex portion is separated from the exhaust opening in the axial direction; a second position where the height of the convex portion in the axial direction overlaps with the height of the exhaust opening in the axial direction; and a third position where the circular plate portion abuts against the base plate. As the exhaust cover moves downward from the first position, in the second position, the distance between the inner peripheral sidewall of the exhaust opening and the outer peripheral sidewall of the convex portion is less than the distance between the upper end of the exhaust opening and the lower end of the outer peripheral portion of the circular plate portion of the exhaust cover above the upper end. Before reaching the third position, the overlap of the height position of the convex portion and the exhaust opening in the axial direction increases.

2. The plasma processing apparatus according to claim 1, characterized in that, A chamfered portion is formed on the outer periphery of the end of the convex portion on the side of the exhaust opening.

3. The plasma processing apparatus according to claim 1, characterized in that, A chamfer is formed on the inner periphery of the end of the convex portion side of the exhaust opening.

4. The plasma processing apparatus according to claim 1, characterized in that, The circular plate portion has a peripheral groove on the surface opposite to the base plate, and an O-ring is disposed within the peripheral groove. The distance between the inner peripheral sidewall of the convex portion having the exhaust opening in the second position and the outer peripheral sidewall of the convex portion is smaller than the distance between the upper surface of the base plate surrounding the upper end of the exhaust opening and the lower end of the O-ring seal.

5. The plasma processing apparatus according to claim 4, characterized in that, At the third position, the circular plate portion abuts against the base plate through the O-ring seal.

6. The plasma processing apparatus according to claim 1, characterized in that, The exhaust cover has an arm that protrudes radially outward from the circular plate portion, and the arm is connected to the telescopic shaft of the actuator.

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