JP5962922B2 - Plasma processing apparatus and plasma processing method - Google Patents

Description

  The present invention relates to a plasma processing apparatus and a plasma processing method, and more particularly to a technique effective for plasma processing of a wafer held on a transport carrier including an annular frame and a holding sheet.

  As a plasma processing apparatus, one disclosed in Patent Document 1 is known. This plasma processing apparatus is intended for processing a wafer held on a transport carrier comprising an annular frame and a holding sheet. In this plasma processing apparatus, when the wafer is diced with plasma, the annular frame is prevented from being exposed to plasma by covering the annular frame with a cover ring.

JP 2012-248741 A

  By the way, in the said plasma processing apparatus, the cover ring itself is also exposed to plasma and becomes high temperature. For this reason, it becomes difficult to radiate heat from the space covered by the cover ring, and the transport carrier is heated. As a result, there is a possibility that the holding sheet is deformed due to a thermal effect or sticks to the cover ring and causes a conveyance trouble.

  Therefore, an object of the present invention is to provide a plasma processing apparatus and a plasma processing method in which the holding sheet is not adversely affected even when the plasma processing is performed.

The first aspect of the present invention is:
A plasma processing apparatus for performing plasma processing on a substrate held by a carrier carrying an annular frame and a holding sheet,
A chamber having an internal space capable of decompression;
A plasma source for generating plasma in the chamber;
A stage provided in the chamber and on which the carrier is placed;
Covering the transport carrier is disposed above the stage, a bottom surface, a cover having a formed window so as to penetrate in the thickness direction,
A relative position of the cover with respect to the stage is separated from the stage, a first position that allows loading and unloading of the carrier on the stage, the cover covers the carrier carried on the stage, and the window portion A drive mechanism that changes to a second position that exposes the substrate held by the holding sheet;
Cooling means for cooling the stage;
A plasma processing apparatus comprising:
The stage has an exterior portion that the bottom surface of the cover located at the second position surrounds the electrode portion and connected to the electrode portion to the high-frequency power source is in contact,
The cooling means cools the electrode part and the exterior part.

  With this configuration, not only the transport carrier can be cooled via the second electrode portion of the stage, but also the cover can be cooled via the exterior portion of the stage. Therefore, there is no problem that the holding sheet of the transport carrier is deformed or adhered due to the thermal influence from the cover that has been exposed to plasma and heated to a high temperature.

The cooling means supplies a first refrigerant flow path formed on the electrodes of the stage, and a second refrigerant flow path formed in the exterior portion of the stage, the refrigerant to the each refrigerant passage And a refrigerant circulation device for circulation.

  With this configuration, the cover can be cooled not only through the second electrode portion but also through the exterior body with a simple configuration in which the first refrigerant channel and the second refrigerant channel are formed.

  The refrigerant circulation device includes a first refrigerant circulation device that supplies and circulates refrigerant to the first refrigerant flow channel, and a second cooling device that supplies and circulates refrigerant to the second refrigerant circulation flow channel. Is preferred.

  With this configuration, the temperature of the second electrode portion and the exterior portion of the stage can be individually controlled. Therefore, it is possible to cool the second electrode part and the cover via the exterior part at an appropriate timing according to the situation during or after the plasma treatment. Therefore, it is possible to effectively eliminate the adverse effect of the heat of the transport carrier, particularly the holding sheet.

  When the plasma is generated in the chamber by the plasma source, it is preferable that the cooling of the exterior body by the second refrigerant circulation device is stopped.

  With this configuration, it is possible to prevent the cover from being cooled excessively by the second refrigerant circulation device via the outer casing and adversely affecting the plasma processing.

The second aspect of the present invention is:
A plasma processing method for performing plasma processing on a substrate held by a carrier carrying an annular frame and a holding sheet,
Holding a substrate on a holding sheet of the carrier,
The carrier carrying the substrate is carried into the chamber of the plasma processing apparatus and placed on the stage,
Cover the transport carrier with a cover placed above the stage ,
Plasma is generated in the chamber, and the substrate is subjected to plasma treatment through a window formed in the cover,
While cooling the said conveyance carrier through the electrode part of the said stage, the said cover is cooled via the exterior part surrounding the electrode part of the said stage.

  According to the present invention, since the cover can be cooled via the exterior portion, it is possible to prevent the holding sheet from being deformed by the radiant heat from the transport carrier, particularly the cover heated to a high temperature.

1 is a schematic front sectional view of a dry etching apparatus according to an embodiment. It is a top view of the cover of the dry etching apparatus shown in FIG. It is the sectional view on the AA line (upward position) of FIG. FIG. 3 is a cross-sectional view taken along line AA in FIG. 2 (downward position).

  Embodiments according to the present invention will be described below with reference to the accompanying drawings. In the following description, terms indicating specific directions and positions (for example, terms including “up”, “down”, “side”, “end”) are used as necessary. Is for facilitating understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Further, the following description is merely illustrative in nature and is not intended to limit the present invention, its application, or its use.

  FIG. 1 shows a dry etching apparatus 1 which is an example of a plasma processing apparatus according to an embodiment of the present invention. In this embodiment, the dry etching apparatus 1 performs plasma dicing and subsequent ashing on the wafer (substrate) 2. Plasma dicing is a method in which a wafer on which a plurality of IC parts (semiconductor devices) are formed is cut at a boundary line (street) using dry etching and divided into individual IC parts. Referring to FIGS. 3A and 3B, a wafer 2 that is circular in the present embodiment has a front surface 2a on which an IC portion or the like (not shown) is formed, and a back surface 2b opposite to the front surface 2a (an IC portion or the like is formed). Not provided). A mask 3 is formed on the surface 2a of the wafer 2 with a pattern for plasma dicing.

  The dry etching apparatus 1 includes a chamber 11 that can be depressurized. In the chamber 11, the transport carrier 5 can be stored in the internal space via an entrance / exit (not shown). The transport carrier 5 includes a holding sheet 6 that detachably holds the wafer 2. As the holding sheet 6, for example, a so-called UV tape that can be elastically stretched and holds the wafer 2 by adhesive force, but changes its chemical characteristics due to irradiation of ultraviolet rays and greatly reduces the adhesive force can be used. . As shown in FIG. 3A, one surface is an adhesive surface (adhesive surface 6a) and the other is an adhesive surface (non-adhesive surface 6b). The holding sheet 6 is flexible and can be easily bent by itself to maintain a fixed shape. For this reason, a substantially ring-shaped frame (annular frame) 7 is attached to the adhesive surface 6 a near the outer peripheral edge of the holding sheet 6. The frame 7 is made of, for example, metal, and has rigidity capable of holding the shape together with the holding sheet 6.

  The wafer 2 is held on the holding sheet 6 of the transport carrier 5 by sticking the back surface 2b to the adhesive surface 6a. As shown in FIG. 2, the wafer 2 is disposed in the center of a circular region 6 c surrounded by the frame 7 on the adhesive surface 6 a of the holding sheet 6. Specifically, the position of the wafer 2 with respect to the holding sheet 6 is such that the center Cs of the circular region 6c and the center Cw of the wafer 2 (center when the wafer 2 is viewed from the front surface 2a or the back surface 2b) are substantially coincident. Is set. By disposing the wafer 2 in the center of the circular region 6 c, a wide annular region 6 d having a constant width is formed between the wafer 2 of the holding sheet 6 and the frame 7.

  Referring to FIGS. 1 to 3B, an antenna (plasma source) 13 is disposed as an upper electrode above a dielectric wall 12 that closes the top of a chamber (vacuum vessel) 11 of the dry etching apparatus 1. The antenna 13 is electrically connected to the first high frequency power supply unit 14A. On the other hand, on the bottom side in the chamber 11, the stage unit 16 on which the transfer carrier 5 holding the wafer 2 is placed as described above is arranged. A process gas source 17 and an ashing gas source 18 are connected to the gas introduction port 11a of the chamber 11, and a decompression mechanism 19 including a vacuum pump for evacuating the chamber 11 is connected to the exhaust port 11b.

  The stage unit 16 includes an electrode unit 21 that is electrically connected to the second high-frequency power source unit 14 </ b> B, and an exterior unit that surrounds the outer periphery of the electrode unit 21. The exterior portion includes a first exterior portion 22A and a second exterior portion 22B that surrounds the outer periphery of the first exterior portion 22A. As will be described later, the electrode portion 21 is made of a dielectric in the vicinity of the upper end surface 21a in which the electrostatic attraction electrode 26 is built, that is, the uppermost portion, but the other portion is made of metal. The upper end surface 21a of the electrode portion 21 and the upper end surface 22a of the first exterior portion 22A constitute a mounting surface 23 that is one horizontal surface on which the transfer carrier 5 holding the wafer 2 is mounted. The first exterior portion 22A is made of a dielectric or an insulator, and the second exterior portion 22B is made of an earth shield material (a metal having conductivity and etching resistance). Therefore, the electrode portion 21 is insulated from the surroundings by the second exterior portion 22B and the first exterior portion 22A. The transport carrier 5 is placed on the stage unit 16 with the holding sheet 6 holding the wafer 2 (adhesive surface 6 a) facing upward, and the non-adhesive surface 6 b of the holding sheet 6 is placed on the stage unit 16. It is placed on the surface 23. The transport carrier 5 is placed at a predetermined position and posture (including a rotation angle position around the center Cs of the circular region 6c of the holding sheet 6) with respect to the placement surface 23 of the stage unit 16 by a transport mechanism (not shown). Is done. Hereinafter, the predetermined position and posture are referred to as a normal position.

  The dry etching apparatus 1 includes a first cooling device 24A and a second cooling device 24B in the stage unit 16, respectively. The first cooling device 24A includes a first refrigerant channel 21b formed in the electrode portion 21, and a first refrigerant circulation device 25A that circulates the temperature-controlled refrigerant in the first refrigerant channel 21b. The second cooling device 24B includes a second refrigerant channel 22b formed in the second exterior portion 22B, and a second refrigerant circulation device 25B that circulates the temperature-controlled refrigerant to the second refrigerant channel 22b.

  In the vicinity of the upper end surface 21 a of the electrode portion 21, a bipolar type electrode 26 for electrostatic attraction is built in this embodiment. A DC power source 27 is electrically connected to the electrostatic adsorption electrode 26.

A cover 31 that can be raised and lowered above the placement surface 23 of the stage section 16 is provided in the chamber 11.
The cover 31 has a circular outer contour and a certain thin thickness, and covers the holding sheet 6 and the frame 7 of the transport carrier 5 and protects them from plasma during plasma processing. For this reason, the cover 31 is formed sufficiently larger than the outer contour of the transport carrier 5. In the present embodiment, the cover 31 is made of a dielectric material such as ceramic and has a size that protrudes outward from the second exterior portion 22B.

  As shown in FIGS. 3A and 3B, the cover 31 is formed with a tapered recess 32c that gradually decreases toward the center on the upper surface. A window portion 33 penetrating in the thickness direction from the upper surface 32a to the lower surface 32b is formed at the center of the tapered recess 32c. The window 33 is sized and shaped so that the holding sheet 6 on the transport carrier 5 is not directly exposed to plasma generated as described later.

  The cover 31 includes a mounting surface 36a on the lower surface 32b, which is first mounted on the upper end surfaces of the drive rods 37A and 37B from the outer peripheral portion toward the inner peripheral opening. The rods 37A and 37B penetrate the second exterior part 22B of the stage part 16 and raise and lower the cover 31. The cover 31 is in a lowered position, which will be described later, and the placement surface 36a is in surface contact with the upper surface of the second exterior portion 22B. In this surface contact state, the cover 31 is cooled via the second exterior portion 22B cooled by the second cooling device 24B. An inner peripheral surface extends upward from the inner peripheral edge of the mounting surface 36 a, and a ceiling surface 36 b extending in parallel with the upper surface of the frame 7 from the upper end toward the upper side of the inner peripheral portion of the frame 7 is provided. In addition, an inclined surface 36c extending obliquely downward is provided at a portion corresponding to the tapered recess 32c from the ceiling surface 36b without substantially changing the thickness. Furthermore, an opposing surface 36d that extends closest to and parallel to the upper surface of the transport carrier 5 from the inclined surface 36c is provided.

  The drive rods 37A and 37B are driven up and down by a drive mechanism 38 conceptually shown only in FIG. The cover 31 is raised and lowered by raising and lowering the drive rods 37A and 37B. Specifically, the cover 31 is movable between a raised position (first position) shown in FIG. 3A and a lowered position (second position) shown in FIG. 3B.

  As shown in FIG. 3A, the cover 31 in the raised position is located above the placement surface 23 of the stage unit 16 with a sufficient interval. Therefore, if the cover 31 is in the raised position, a loading operation for placing the transfer carrier 5 (holding the wafer 2) on the mounting surface 23 and an unloading operation for lowering the conveyance carrier 5 from the mounting surface 23 are possible. It is.

  As shown in FIG. 3B, when the cover 31 is in the lowered position, the holding sheet 6 (except the portion holding the wafer 2) and the frame 7 of the transport carrier 5 in the regular position are covered with the cover 31. Further, the frame 7 is housed in a housing groove 36 formed in the lower surface 32 b of the cover 31 and does not contact the cover 31. Then, when the lower surface 32b of the cover 31 comes into contact with the mounting surface 23 of the stage unit 16, heat is radiated from the cover 31 exposed to plasma to the stage unit 16 side due to the temperature rise.

  A control device 40 schematically shown only in FIG. 1 includes first and second high-frequency power supply units 14A and 14B, a process gas source 17, an ashing gas source 18, a decompression mechanism 19, a cooling device 24, a DC power source 27, and a drive. The operation of each element constituting the dry etching apparatus 1 including the mechanism 38 is controlled.

  Next, operation | movement of the dry etching apparatus 1 of this embodiment is demonstrated.

  First, the transport carrier 5 having the wafer 2 adhered to the center of the circular area 6c of the holding sheet 6 is carried into the chamber 11 by a transport mechanism (not shown) and placed at a regular position on the placement surface 23 of the stage unit 16. . At this time, the cover 31 is in the raised position (FIG. 3A).

  Then, the drive rods 37A and 37B are driven by the drive mechanism 38, and the cover 31 is lowered from the raised position (FIG. 3A) to the lowered position (FIG. 3B). When the cover 31 is in the lowered position, the holding sheet 6 and the frame 7 of the transport carrier 5 are covered with the cover 31, and the wafer 2 is exposed from the window 33.

  Subsequently, a DC voltage is applied from the DC power source 27 to the electrostatic chucking electrode 26, and the wafer 2 is held on the mounting surface 23 of the stage unit 16 (the upper end surface 21 a of the electrode unit 21) by electrostatic chucking.

  Further, while introducing a process gas for plasma dicing from the process gas source 17 into the chamber 11, the process chamber 15 is exhausted by the decompression mechanism 19 to maintain the processing chamber 15 at a predetermined pressure. Thereafter, high frequency power is supplied from the high frequency power supply unit 14 </ b> A to the antenna 13 to generate plasma P in the chamber 11 and irradiate the wafer 2 exposed from the window 33 of the cover 31. At this time, a bias voltage is applied to the electrode part 21 of the stage part 16 from the high frequency power supply part 14B. As a result, the portion (street) exposed from the mask 3 of the wafer 2 is removed from the front surface 2a to the back surface 2b by the physicochemical action of radicals and ions in the plasma P, and the wafer 2 is divided into individual chips. The

  At this time, only the first cooling device 24A is driven, and the temperature-controlled refrigerant is caused to flow only in the first refrigerant flow path 21b formed in the electrode portion 21. As a result, the wafer 2 on the transport carrier 5 placed on the placement surface 23 of the stage unit 16 is cooled. However, at this stage, although the second cooling device 24B is driven, positive cooling is not performed. In this case, either the method of stopping the circulation of the refrigerant without stopping the cooling of the refrigerant or the method of stopping the cooling of the refrigerant can be adopted although the circulation of the refrigerant is continued. Thereby, it is possible to prevent the cover 31 from being excessively cooled and adversely affecting the plasma processing. Further, since the cover 31 is appropriately cooled, it is possible to eliminate an adverse effect due to heat on the holding sheet 6.

  Ashing is performed after plasma dicing is completed. While introducing an ashing process gas (for example, oxygen gas) from the ashing gas source 18 into the chamber 11, the pressure is reduced by the decompression mechanism 19 to maintain the processing chamber 15 at a predetermined pressure. Thereafter, high frequency power is supplied from the high frequency power supply unit 14 </ b> A to the antenna 13 to generate plasma P in the chamber 11 and irradiate the wafer 2 exposed from the window 33 of the cover 31. The mask 3 is completely removed from the surface 2 a of the wafer 2 by the irradiation with the oxygen plasma P.

  During this time, the second cooling device 24B is also driven, and the temperature-controlled refrigerant is caused to flow also in the second refrigerant flow path 22b formed in the second exterior portion 22B. Thereby, the cover 31 heated under the influence of plasma can be cooled via the second exterior portion 22B.

  Further, after ashing, the residual gas in the chamber 11 is exhausted, and instead, nitrogen gas, which is an inert gas, is supplied to cool the wafer 2, the cover 31, and the like. The supplied nitrogen gas is exhausted. Thereby, it is possible to reliably cool a portion that is not completely cooled by the first cooling device 24A and the second cooling device 24B. Then, the drive rods 37A and 37B are driven by the drive mechanism 38 to move the cover 31 from the lowered position to the raised position. Thereafter, the transport carrier 5 is unloaded from the chamber 11 by a transport mechanism (not shown).

  As described above, in the embodiment, not only the electrode portion 21 of the stage portion 16 is cooled by the first cooling device 24A, but also the second exterior portion 22B of the stage portion 16 is cooled by the second cooling device 24B. The mounted cover 31 can also be cooled. Therefore, it is possible to effectively eliminate the thermal influence on the transport carrier 5, particularly the holding sheet 6. Moreover, since the inside of the chamber 11 is cooled by supplying nitrogen gas into the chamber 11 after ashing, the first cooling device 24A and the second cooling device 24B can also cool portions that are insufficient. And the deformation of the protective sheet 6 can be more effectively prevented.

  In addition, this invention is not limited to the structure described in the said embodiment, A various change is possible.

  For example, in the embodiment, the cooling start timing by the first cooling device 24A and the cooling start timing by the second cooling device 24B are shifted, but the cooling may be started at the same time, The time can be set freely.

  Moreover, in the said embodiment, although the electrode part 21 and the 2nd exterior part 22B of the stage part 16 were cooled by separate cooling device 24A, 24B, respectively, the 1st refrigerant flow path 21b and the 2nd refrigerant flow path By connecting 22b in series, the refrigerant adjusted in temperature by a single refrigerant device can be circulated. According to this, it becomes possible to simplify a structure and produce it cheaply.

  In the above embodiment, the entire cover 31 is made of a single ceramic material. However, the cover 31 may be made of another material (for example, a carbon material), or a combination of a plurality of materials instead of a single material. It is good also as a structure.

  Moreover, in the said embodiment, although the electrode for electrostatic attraction was made into the bipolar type, it is not limited to this, It is good also as a monopolar type.

  Furthermore, in the above-described embodiment, the processing performed by the dry etching apparatus 1 has been described with respect to examples of plasma dicing and ashing. However, the present invention is not limited to this, and may be normal dry etching, for example. The dry etching apparatus is not limited to the ICP type as in the embodiment, and may be a parallel plate type. Furthermore, the present invention is not limited to a dry etching apparatus, but can be applied to other plasma processing apparatuses such as a CVD apparatus.

1 Dry Etching Equipment 2 Wafer (Substrate)
2a Front surface 2b Back surface 3 Mask 5 Transport carrier 6 Holding sheet 6a Adhesive surface 6b Non-adhesive surface 6c Circular region 6d Annular region 7 Frame 11 Chamber 11a Gas inlet 11b Exhaust port 12 Dielectric wall 13 Antenna (plasma source)
14A, 14B High frequency power supply 15 Treatment room 16 Stage part (stage)
17 Process gas source 18 Ashing gas source 19 Decompression mechanism 21 Electrode portion 21a Upper end surface 21b First refrigerant flow path 22A First exterior portion 22B Second exterior portion 22a Upper end surface 22b Second refrigerant flow path 23 Mounting surface 24A First cooling Device 24B Second cooling device 25A First refrigerant circulation device 25B Second refrigerant circulation device 26 Electrostatic adsorption electrode 27 DC power supply 31 Cover 32a Upper surface 32b Lower surface 32c Tapered depression 33 Window portion 36 Storage groove 36a Mounting surface 36b Ceiling Surface 36c Inclined surface 36d Opposing surfaces 37A, 37B Drive rod 38 Drive mechanism 40 Control device

Claims (5)

A plasma processing apparatus for performing plasma processing on a substrate held by a carrier carrying an annular frame and a holding sheet,
A chamber having an internal space capable of decompression;
A plasma source for generating plasma in the chamber;
A stage provided in the chamber and on which the carrier is placed;
Covering the transport carrier is disposed above the stage, a bottom surface, a cover having a formed window so as to penetrate in the thickness direction,
A relative position of the cover with respect to the stage is separated from the stage, a first position that allows loading and unloading of the carrier on the stage, the cover covers the carrier carried on the stage, and the window portion A drive mechanism that changes to a second position that exposes the substrate held by the holding sheet;
Cooling means for cooling the stage;
A plasma processing apparatus comprising:
The stage has an exterior portion that the bottom surface of the cover located at the second position surrounds the electrode portion and connected to the electrode portion to the high-frequency power source is in contact,
The plasma processing apparatus, wherein the cooling means cools the electrode part and the exterior part. The cooling means supplies a first refrigerant flow path formed on the electrodes of the stage, and a second refrigerant flow path formed in the exterior portion of the stage, the refrigerant to the each refrigerant passage The plasma processing apparatus according to claim 1, further comprising a refrigerant circulation device for circulating the refrigerant.   The refrigerant circulation device includes a first refrigerant circulation device that supplies and circulates refrigerant to the first refrigerant flow channel, and a second refrigerant circulation device that supplies and circulates refrigerant to the second refrigerant flow channel. The plasma processing apparatus according to claim 2.   The plasma processing apparatus according to claim 3, wherein when the plasma is generated in the chamber by the plasma source, cooling of the exterior body by the second refrigerant circulation device is stopped. A plasma processing method for performing plasma processing on a substrate held by a carrier carrying an annular frame and a holding sheet,
Holding a substrate on a holding sheet of the carrier,
The carrier carrying the substrate is carried into the chamber of the plasma processing apparatus and placed on the stage,
Cover the transport carrier with a cover placed above the stage ,
Plasma is generated in the chamber, and the substrate is subjected to plasma treatment through a window formed in the cover,
A plasma processing method, wherein the carrier is cooled via an electrode portion of the stage and the cover is cooled via an exterior portion surrounding the electrode portion of the stage.

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