JP2005175368A - Plasma processing equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plasma processing apparatus in which generation of particles is reduced by suppressing concentration of discharge in a local area of a clamp ring, a shield ring and a uniform ring during plasma processing.
A wafer covering portion 53a of a clamp ring 53 has an upper surface 53b facing substantially upward, a first inner wall surface 53c constituting the innermost periphery of the wafer covering portion 53a, and a first lower surface facing a semiconductor wafer W. 53d, the second inner wall surface 53e constituting the step and the second lower surface 53f in contact with the semiconductor wafer W. Here, a ridge 53g formed by the first inner wall surface 53c constituting the innermost periphery of the wafer covering portion 53a and the upper surface 53b adjacent above the first inner wall surface 53c, and the first inner wall surface 53c, adjacent below the first inner wall surface 53c. The ridges 53h formed by the first lower surface 53d are subjected to R chamfering of R0.2 mm by mechanical grinding.
[Selection] Figure 2

Description

  The present invention relates to a plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container.

  In a plasma processing apparatus, for example, a plasma etching apparatus used for manufacturing a semiconductor, a semiconductor wafer as an object to be processed placed in an airtight container is exposed to plasma for dry etching. The semiconductor wafer is mounted on a lower electrode as a mounting table, and plasma is generated by applying high-frequency power or the like between the upper electrode disposed opposite to the lower electrode while injecting an etching gas. The semiconductor wafer surface is etched by being generated.

  Here, the semiconductor wafer is mechanically fixed on the lower electrode by a clamp ring. In addition, a shield ring is attached to the upper electrode so as to generate plasma in approximately the same size as the semiconductor wafer, and covers the outer peripheral edge of the upper electrode. Further, a uniformizing ring for performing the etching process uniformly may be provided outside the semiconductor wafer. Note that these clamp ring, shield ring, and uniform ring are formed of alumina ceramics or the like having good insulation and durability against plasma (for example, Patent Documents 1 and 2).

JP-A-10-92796 JP 2002-43287 A

  However, even if alumina ceramics with excellent plasma durability are used for materials such as clamp rings, it is difficult to completely prevent damage due to plasma. Depending on the shape, discharge concentrates during the process and erodes. As a result, the particles are scattered on the surface of the semiconductor wafer and the manufacturing yield is lowered.

  The present invention has been made in view of the above problems, and its purpose is to reduce the generation of particles by suppressing the concentration of discharge in the local area of the clamp ring, shield ring, and uniformizing ring during plasma processing. It is to provide a plasma processing apparatus.

  The plasma processing apparatus of the present invention is a plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container. A mounting table for mounting the body, and a clamp ring that covers the periphery of the object to be processed placed on the mounting table and holds the object to be processed on the mounting table, In the workpiece covering portion of the clamp ring, the ridge formed by the inner wall surface constituting the innermost periphery and the surface vertically adjacent to the inner wall surface is both chamfered with a convex curved surface. It is characterized by.

  The plasma processing apparatus of the present invention is a plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container. A mounting table for mounting the body, and a clamp ring that covers the periphery of the object to be processed placed on the mounting table and holds the object to be processed on the mounting table, In the workpiece covering portion of the clamp ring, the ridge constituting the innermost circumference is chamfered with a convex curved surface.

  The plasma processing apparatus of the present invention is a plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container. A mounting table for mounting a body; an upper electrode provided facing the mounting table; and a shield ring that covers a peripheral portion of the upper electrode and regulates a plasma generation range; In the upper electrode covering portion of the ring, the ridge formed by the inner wall surface constituting the innermost periphery and the surface vertically adjacent to the inner wall surface is chamfered with a convex curved surface. To do.

  The plasma processing apparatus of the present invention is a plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container. A mounting table for mounting a body; an upper electrode provided facing the mounting table; and a shield ring that covers a peripheral portion of the upper electrode and regulates a plasma generation range; In the upper electrode covering portion of the ring, the ridge constituting the innermost circumference is chamfered with a convex curved surface.

  The plasma processing apparatus of the present invention is a plasma processing apparatus that generates a plasma in an airtight container and performs a predetermined process on an object to be processed placed in the airtight container. The rim formed by the upper surface and the inner wall surface of the homogenizing ring is chamfered with a convex curved surface.

  In this plasma processing apparatus, it is desirable that a radius of curvature of the convex curved surface is 0.15 mm or more.

  If there are corners on the surface of the clamp ring, shield ring, or uniform ring exposed to high-density plasma, it is not only mechanically weaker than the curved part, but also the charge tends to concentrate on the corners. It is easy to attract seeds, and as a result, the corners are more susceptible to damage caused by collision of active species than other parts.

  However, according to the present invention, since there are no corners on the surface around the inner periphery of the clamp ring, shield ring, or uniformizing ring that are exposed to high-density plasma, it is possible to suppress the concentration of charges. Damage can be suppressed. As a result, the generation of particles can be reduced.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In addition, the embodiment shown below does not limit the content of the invention described in the claim at all. Further, all of the configurations shown below are not necessarily essential as means for solving the invention described in the claims.

(First embodiment)
A plasma processing apparatus according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic cross-sectional view showing the overall configuration of a plasma etching apparatus as a plasma processing apparatus in the present embodiment. Here, the plasma etching apparatus 10 performs an etching process on a semiconductor wafer as an object to be processed.

  As shown in FIG. 1, the plasma etching apparatus 10 includes a cylindrical airtight container 20 formed of, for example, aluminum whose surface is anodized. An opening 21 for carrying in and out the semiconductor wafer W is provided on the side surface of the airtight container 20, and can be opened and closed by a gate valve 21a. Further, an exhaust pipe 22 is provided on the other side surface of the airtight container 20, and a desired vacuum state, for example, about several Pa to several tens Pa can be achieved by a vacuum pump (not shown).

  In the upper part of the airtight container 20, there is provided an upper electrode 30 which is formed in a hollow disk shape, for example, aluminum whose surface is anodized. The upper electrode 30 is connected to a gas supply pipe 31 for introducing an etching gas from a gas supply source (not shown) into the hollow portion. In addition, a large number of small holes 32 are provided on the lower surface of the upper electrode 30, and the etching gas can flow into the hermetic container 20 from the small holes 32. Further, the upper electrode 30 is connected to a high frequency power source 40 having a power of about 500 to 1500 W and a frequency of about 300 kHz to 13 MHz, for example. A shield ring 33 made of a material excellent in insulation and plasma durability such as alumina ceramic is provided around the lower side of the upper electrode 30 so that plasma is generated in a region of approximately the same size as the semiconductor wafer W. The outer peripheral edge of the lower surface of the upper electrode 30 is covered. The upper electrode 30 may be formed of carbon or silicon.

  A lower electrode 50 is provided in the lower part of the hermetic container 20, which has a disk shape, and is formed of, for example, aluminum whose surface is anodized, and is grounded. The lower electrode 50 also serves as a mounting table for the semiconductor wafer W. The lower electrode 50 and the semiconductor wafer W placed on the lower electrode 50 are raised and lowered by driving the lifting shaft 51 up and down by a lifting mechanism (not shown). It is possible to descend.

  The back surface of the lower electrode 50 and the bottom of the hermetic container 20 are hermetically connected via a bellows 52 provided to be extendable and contracted, so that the airtightness in the hermetic container 20 is not affected without raising or lowering the lower electrode 50. The sex is secured.

  The upper surface of the lower electrode 50 is provided with a clamp ring 53 made of a material having excellent insulating properties and plasma durability such as alumina ceramic, and the inner peripheral edge of the surface of the semiconductor wafer W on the lower electrode 50 is provided. The outer peripheral edge is pressed and held. The clamp ring 53 is fixed to the ceiling portion of the airtight container 20 by a plurality of clamp shafts 54, and the semiconductor wafer W is held and released by raising and lowering the lower electrode 50.

  Next, details of the clamp ring 53 and the shield ring 33 will be described with reference to FIGS. FIG. 2 is an enlarged cross-sectional view of the main part of the clamp ring 53, and FIG. 3 is an enlarged cross-sectional view of the main part of the shield ring 33.

  As shown in FIG. 2, the wafer covering portion 53a as the workpiece covering portion of the clamp ring 53 is a portion covering the semiconductor wafer W at the inner peripheral edge of the clamp ring 53, and faces substantially upward. The upper surface 53b, the first inner wall surface 53c that constitutes the innermost circumference of the wafer covering portion 53a, the first lower surface 53d that faces the semiconductor wafer W, the second inner wall surface 53e that constitutes a step, and the semiconductor wafer W abut. It is composed of a second lower surface 53f. Here, a ridge 53g formed by the first inner wall surface 53c constituting the innermost periphery of the wafer covering portion 53a and the upper surface 53b adjacent above the first inner wall surface 53c, and the first inner wall surface 53c, adjacent below the first inner wall surface 53c. The ridges 53h formed by the first lower surface 53d are subjected to R chamfering of R0.2 mm by mechanical grinding.

  On the other hand, as shown in FIG. 3, the upper electrode covering portion 33 a of the shield ring 33 is a portion covering the upper electrode 30 at the inner peripheral edge of the shield ring 33, facing substantially downward, and a curved lower surface. 33b and an upper surface 33c that contacts the upper electrode 30. The innermost circumference of the upper electrode covering portion 33a is constituted by a ridge 33d formed by the lower surface 33b and the upper surface 33c. The ridge 33d is also subjected to R 0.2 mm chamfering by mechanical grinding. Yes.

  Next, the operation of the plasma etching apparatus 10 as the plasma processing apparatus of this embodiment will be described with reference to FIG. 1 again.

  First, in a state where the lower electrode 50 is lowered to a position indicated by a two-dot chain line, an unprocessed semiconductor wafer W is carried into the hermetic container 20 from the outside of the opening 21 by an unillustrated transfer mechanism, Placed on. Next, after the inside of the airtight container 20 is sealed, the elevating shaft 51 is driven to raise the lower electrode 50, and the outer peripheral edge of the semiconductor wafer W is brought into contact with and fixed to the clamp ring 53. The inside of the airtight container 20 is evacuated to a predetermined degree of vacuum, for example, about several Pa to several tens Pa by a vacuum pump (not shown) provided outside the exhaust pipe 22.

Next, an etching gas such as CHF ₃ , CF ₄ , and Ar is supplied from a gas supply source (not shown) to the upper electrode 30 through the gas supply pipe 31, and the etching gas is sealed in an airtight container through a small hole 32 on the lower surface of the upper electrode 30. 20 flows out into the interior. At the same time, a high frequency voltage is applied to the upper electrode 30 by the high frequency power source 40 to generate plasma in the space between the grounded lower electrode 50. The semiconductor wafer W on the lower electrode 50 is etched by this plasma.

  When the etching is completed, the opposite process to that described above, that is, the lower electrode 50 on which the semiconductor wafer W is placed is lowered to a position indicated by a two-dot chain line, and the semiconductor wafer W processed from the opening 21 by a transfer mechanism (not shown). Is taken out.

  During the above-described etching process, the clamp ring 53 and the shield ring 33 as well as the semiconductor wafer W are exposed to the plasma. However, the clamp ring 53 and the shield ring 33 of the present embodiment have R chamfering (chamfering with a convex curved surface) on the ridge at the inner peripheral edge that is exposed to high-density plasma, and the angle at which charges are likely to concentrate. Since it does not have a part, concentration of discharge can be suppressed and generation of particles can be suppressed.

  Here, the result of actually confirming the number of generated particles according to the presence or absence of R chamfering at the inner peripheral edge of the clamp ring 53 is shown.

An RF power of 700 W, an RF frequency of 380 kHz, a pressure of 200 mTorr, an etching gas of CHF ₃ / CF ₄ / Ar, and a flow rate of 20/25/200 SCCM, respectively, after processing for 60 seconds, on a semiconductor wafer The number of scattered particles having a particle size of 0.3 mm or more was confirmed.

  As a result, when using a clamp ring with corners and no R chamfering on the inner peripheral edge, 97 particles were confirmed, whereas an R chamfering of R0.2 mm was made on the edge of the inner peripheral edge. When using the applied clamp ring, the number of particles was only 8.

  As described above, according to the plasma etching apparatus 10 of the present embodiment, the following effects can be obtained.

  According to the present embodiment, the chamfers 33d, 53g, 53h of the portions constituting the innermost periphery of the upper electrode covering portion 33a of the shield ring 33 and the wafer covering portion 53a of the clamp ring 53 are subjected to R chamfering. Therefore, even if the portion is exposed to high-density plasma, the concentration of discharge can be suppressed. As a result, it is possible to reduce particles generated when the shield ring 33 and the clamp ring 53 are eroded by plasma.

(Second Embodiment)
A plasma processing apparatus according to a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a schematic cross-sectional view showing the overall configuration of a plasma etching apparatus as a plasma processing apparatus in the present embodiment. Here, as in the first embodiment, the plasma etching apparatus 60 performs etching processing on a semiconductor wafer as an object to be processed. In this embodiment, plasma etching apparatus 60 uses ECR plasma generated by ECR (electron magnetron resonance) discharge. It is an ECR plasma etching apparatus that performs processing.

  As shown in FIG. 4, a waveguide 61 that guides microwaves generated from a magnetron (not shown) is provided above the plasma etching apparatus 60, and a processing chamber 62 is sealed below the waveguide 61. In addition, a quartz plate 63 for supplying microwaves to the processing chamber 62 is provided.

  The processing chamber 62 is surrounded by a discharge block 64 made of, for example, aluminum, and an inner wall surface thereof is provided with a block cover 65 made of, for example, quartz. Further, the discharge block 64 is supported by a support portion 66, and the exhaust chamber 67 provided below the discharge block 64 is evacuated by a vacuum pump (not shown), so that the processing chamber 62 can be maintained in a vacuum. That is, in this embodiment, the quartz plate 63, the discharge block 64, and the support part 66 function as an airtight container. A solenoid coil 68 for supplying a magnetic field to the processing chamber 62 is disposed around the discharge block 64, and the processing block 62 is inserted into the side of the discharge block 64 through the inside of the discharge block 64. A gas supply pipe 69 for supplying an etching gas is provided.

  A mounting table 70 on which the semiconductor wafer W is mounted is provided below the processing chamber 62. The mounting table 70 can be raised and lowered by a lifting mechanism (not shown), and a high-frequency power source 71 is connected to the mounting table 70. The semiconductor wafer W mounted on the mounting table 70 is held by a clamp ring 72, and a uniformizing ring 73 for uniformly etching the semiconductor wafer W is provided above the clamp ring 72. ing. Here, the clamp ring 72 and the equalizing ring 73 are made of a material excellent in insulation and plasma durability such as alumina ceramic.

  Next, details of the clamp ring 72 and the equalizing ring 73 in the present embodiment will be described with reference to FIG. FIG. 5 is an enlarged cross-sectional view of the main parts of the clamp ring 72 and the equalizing ring 73.

  As shown in FIG. 5, a wafer covering portion 72 a as a workpiece covering portion of the clamp ring 72 is a portion covering the semiconductor wafer W at the inner peripheral edge portion of the clamp ring 72, and an upper surface facing upward. 72b, an inner wall surface 72c constituting the innermost circumference of the wafer covering portion 72a, and a lower surface 72d facing the semiconductor wafer W. Here, a ridge 72e formed by an inner wall surface 72c constituting the innermost periphery of the wafer covering portion 72a and an upper surface 72b adjacent above the inner wall surface 72c, an inner wall surface 72c, and a lower surface 72d adjacent below the inner wall surface 72c. Each of the ridges 72f is subjected to R chamfering of R0.2 mm by mechanical grinding.

  On the other hand, the equalizing ring 73 includes an upper surface 73 a facing upward, an inner wall surface 73 b, an outer wall surface 73 c, and a lower surface 73 d that contacts the clamp ring 72. Here, the ridge 73e formed by the upper surface 73a and the inner wall surface 73b and the ridge 73f formed by the upper surface 73a and the outer wall surface 73c are each subjected to R chamfering of R0.2 mm by mechanical grinding. .

  When processing is performed by the plasma etching apparatus 60 (see FIG. 4) of the present embodiment, first, an unprocessed semiconductor wafer W is mounted on the mounting table 70 by a transport mechanism (not shown) with the mounting table 70 lowered. Put. Next, while introducing an etching gas from the gas supply pipe 69 into the processing chamber 62, the exhaust pipe 67 is evacuated by a vacuum pump (not shown) to adjust the processing chamber 62 to a predetermined pressure, and then the mounting table 70 is raised. Then, the semiconductor wafer W is held in contact with the clamp ring 72. Thereafter, a microwave is generated from a magnetron (not shown), a magnetic field is generated from the solenoid coil 68 to generate a high density plasma in the processing chamber 62, and a high frequency power is applied to the mounting table 70 by a high frequency power source 71. Then, the semiconductor wafer W is etched.

  As described above, according to the plasma etching apparatus 60 of the present embodiment, the edges 73e and 73f formed by the upper surface 73a of the uniformizing ring 73, the inner wall surface 73b, and the outer wall surface 73c are also rounded. Therefore, the same effect as that in the first embodiment can be obtained.

(Modification)
In addition, you may change embodiment of this invention as follows.

  In the above embodiment, two types of plasma etching apparatuses are shown as examples of the plasma processing apparatus, but the form of the plasma etching apparatus is not limited to these. Furthermore, the present invention can also be applied to plasma processing apparatuses other than etching apparatuses, such as plasma CVD apparatuses, sputtering apparatuses, and ion implantation apparatuses.

  In the first embodiment, the example in which the high-frequency power source 40 is connected to the upper electrode 30 and the lower electrode 50 is grounded is shown. However, the upper electrode 30 is grounded by reversing the applied potential, and the lower electrode 50 is grounded. The high frequency power supply 40 may be connected to the power supply. Alternatively, a high frequency voltage may be applied to both electrodes 30 and 50.

  In the first embodiment, the inner wall surface 53c of the wafer covering portion 53a of the clamp ring 53 constitutes the innermost periphery of the wafer covering portion 53a, and the lower surface 33b and the upper surface 33c of the upper electrode covering portion 33a of the shield ring 33 The ridge 33d constitutes the innermost circumference of the upper electrode covering portion 33a, but the portion constituting the innermost circumference of each covering portion is not limited to the above. The portion of the clamp ring 53 that constitutes the innermost circumference of the wafer covering portion 53 a is a ridge, and this may be chamfered, or the innermost circumference of the upper electrode covering portion 33 a of the shield ring 33. The part to be performed is an inner wall surface, and R chamfering may be applied to a ridge between the inner wall surface and a vertically adjacent surface.

  In the second embodiment, the clamp ring 72 and the uniformizing ring 73 are configured separately, but may be a structure in which they are integrated (a clamp ring having the uniformizing ring). .

  In the second embodiment, R chamfering is applied to both the ridge 73e formed by the upper surface 73a and the inner wall surface 73b of the uniformizing ring 73 and the ridge 73f formed by the upper surface 73a and the outer wall surface 73c. However, it is possible to obtain a great effect by only exposing the inner ridge 73e only to the inner edge 73e where the particles are exposed to a higher density plasma and particles are likely to be scattered on the surface of the semiconductor wafer W.

  In the present specification, the direction in which the processing surface of the semiconductor wafer W faces is upward.

1 is a schematic cross-sectional view showing an overall configuration of a plasma etching apparatus according to a first embodiment. The expanded sectional view of the principal part of a clamp ring. The expanded sectional view of the principal part of a shield ring. The schematic cross section which shows the whole structure of the plasma etching apparatus which concerns on 2nd Embodiment. The expanded sectional view of the principal part of a clamp ring and a uniform ring.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Plasma etching apparatus as a plasma processing apparatus, 20 ... Airtight container, 21 ... Opening part, 21a ... Gate valve, 22 ... Exhaust pipe, 30 ... Upper electrode, 31 ... Gas supply pipe, 32 ... Small hole, 33 ... Shield Ring, 33a ... upper electrode covering portion, 33b ... lower surface, 33c ... upper surface, 33d ... ridge, 40 ... high frequency power supply, 50 ... lower electrode as mounting table, 51 ... lifting shaft, 52 ... bellows, 53 ... clamp ring, 53a ... Wafer covering portion as a processing target covering portion, 53b... Upper surface, 53c... First inner wall surface, 53d... First lower surface, 53e ... Second inner wall surface, 53f. Ridge 54 ... Clamp shaft 60 ... Plasma etching apparatus as plasma processing apparatus 61 ... Waveguide 62 ... Processing chamber 63 ... Quartz plate constituting hermetic container 64 ... Airtight container Constructing discharge block, 65 ... Block cover, 66 ... Supporting part constituting an airtight container, 67 ... Exhaust pipe, 68 ... Solenoid coil, 69 ... Gas supply pipe, 70 ... Mounting table, 71 ... High frequency power source, 72 ... Clamp ring 72a ... Wafer coating portion as an object covering portion, 72b ... upper surface, 72c ... inner wall surface, 72d ... lower surface, 72e, 72f ... ridge, 73 ... homogenization ring, 73a ... upper surface, 73b ... inner wall surface, 73c ... Outer wall surface, 73d ... lower surface, 73e, 73f ... ridge, W ... semiconductor wafer as object to be processed.

Claims (6)

A plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container,
A mounting table for mounting the object to be processed in the airtight container;
A peripheral portion of the object to be processed placed on the mounting table, and a clamp ring for holding the object to be processed on the mounting table;
In the workpiece covering portion of the clamp ring, the ridge formed by the inner wall surface constituting the innermost periphery and the surface vertically adjacent to the inner wall surface is both chamfered with a convex curved surface. A plasma processing apparatus. A plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container,
A mounting table for mounting the object to be processed in the airtight container;
A peripheral portion of the object to be processed placed on the mounting table, and a clamp ring for holding the object to be processed on the mounting table;
The plasma processing apparatus characterized in that, in the workpiece covering portion of the clamp ring, the ridge constituting the innermost periphery thereof is chamfered with a convex curved surface. A plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container,
A mounting table for mounting the object to be processed in the airtight container;
An upper electrode provided facing the mounting table;
A shield ring that covers the peripheral edge of the upper electrode and regulates the plasma generation range;
In the upper electrode covering portion of the shield ring, the ridge formed by the inner wall surface constituting the innermost periphery and the surface vertically adjacent to the inner wall surface is both chamfered with a convex curved surface. A plasma processing apparatus. A plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container,
A mounting table for mounting the object to be processed in the airtight container;
An upper electrode provided facing the mounting table;
A shield ring that covers the periphery of the upper electrode and regulates the plasma generation range;
In the upper electrode covering portion of the shield ring, the ridge constituting the innermost circumference is chamfered with a convex curved surface. A plasma processing apparatus for generating a plasma in an airtight container and performing a predetermined process on an object to be processed placed in the airtight container,
In order to perform a uniform plasma treatment, comprising a uniformizing ring disposed around the object to be processed,
The ridge formed by the upper surface and the inner wall surface of the homogenizing ring is chamfered with a convex curved surface. 6. The plasma processing apparatus according to claim 1, wherein a radius of curvature of the convex curved surface is 0.15 mm or more.

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