JP6219178B2 - Plasma etching equipment - Google Patents

Description

  The present invention relates to a chuck table mechanism that is mounted on a processing apparatus such as a plasma etching apparatus and holds a workpiece such as a semiconductor wafer, and more particularly, an electrostatic chuck table that holds and holds a workpiece by using an electrostatic attraction force. Regarding the mechanism.

  In the semiconductor device manufacturing process, the semiconductor wafer is formed to have a predetermined thickness by grinding the back surface of the semiconductor wafer with a grinding device before being divided into individual devices. When the back surface of the wafer is ground, there is a problem that grinding strain remains on the back surface of the wafer and the bending strength of the divided devices is lowered. In order to solve such problems, there has been proposed a plasma etching apparatus that removes grinding distortion generated on the back surface of the wafer by performing plasma etching treatment on the back surface of the wafer and improves the bending strength of the device. (For example, refer to Patent Document 1).

  Since the plasma etching apparatus described above performs the plasma etching process in a vacuum state in the plasma processing chamber, the chuck table that holds the workpiece is in a system that holds the workpiece by vacuum suction. It is difficult to securely hold the chuck table. Therefore, the chuck table of the plasma etching apparatus is generally an electrostatic chuck table that holds the workpiece by suction using an electrostatic attraction force (see Patent Document 2).

  The electrostatic chuck table prevents the temperature of the workpiece from rising above the heat resistance temperature of the surface film (resist, etc.) due to the heat of the plasma entering the workpiece, and the temperature distribution is uniform. For example, a groove for supplying a cooling medium gas is formed between the electrostatic chuck table and the workpiece on the holding surface of the electrostatic chuck table (see Patent Document 3).

JP 2006-73592 A JP 2007-31462 A JP 2000-332091 A

  The workpiece is transported with a protective tape or a rigid substrate attached to the untreated surface. When the protective tape is attached, it is possible to cool the work piece by attaching the protective tape to the holding surface, but when the rigid substrate is attached, the fine unevenness of the holding surface. As a result, the rigid substrate and the holding surface are in point contact and cooling efficiency is lowered.

  An object of the present invention is to provide a plasma etching apparatus that can be efficiently cooled regardless of the method of attaching a protective tape or a rigid substrate.

  In order to solve the above-described problems and achieve the object, a plasma etching apparatus according to the present invention includes a housing including a plasma processing chamber and a workpiece on a holding surface of the housing disposed in the plasma processing chamber. An electrostatic chuck table mechanism having a chuck table that is held by electrostatic adsorption, a processing gas injection unit that injects a processing gas for generating plasma onto a workpiece held on the chuck table, and a pressure reduction in the plasma processing chamber. The electrostatic chuck table mechanism includes a chuck table having a holding surface for holding a workpiece, and a voltage is applied to the chuck table provided inside the chuck table. An electrode for generating a charge by this, voltage applying means for applying a voltage to the electrode, and the chuck table disposed on the surface, A table base having cooling means for cooling the back table, and a groove formed on the holding surface of the chuck table so as to communicate with each other in a honeycomb shape in which regular hexagons are plane-filled over the entire surface. A plurality of projections formed on the holding surface of a regular hexagonal shape, and a plurality of injection holes are formed in the groove, and cooling medium gas is supplied to the groove through the injection holes. The height of the projecting portion provided from the holding surface of each of the convex portions is such that a protective tape attached to the surface of the workpiece is placed in contact with the plurality of convex portions. In addition, when the back surface of the protective tape is formed at a height that makes contact with the holding surface, and the protective tape is attached to the surface of the workpiece that makes contact with the holding surface, The back surface of the protective tape and the char The entire surface of the protective tape is cooled by heat conduction to the cooling means and heat transfer by the cooling medium gas supplied from the groove, and comes into contact with the holding surface of the workpiece. When the rigid substrate is attached to the surface, the rigid substrate is placed in contact with the plurality of convex portions, and a slight gap occurs between the back surface of the rigid substrate and the holding surface of the chuck table, The cooling medium gas supplied from the groove spreads over the gap and the entire rigid substrate is cooled by heat transfer.

  In the present invention, since a plurality of grooves and a plurality of convex portions are formed on a holding surface for holding a workpiece, in the case of a workpiece adhered to a rigid substrate, the holding surface and the workpiece are processed by the convex portions. A gap is formed between the substrate and the cooling medium gas is supplied to the gap, whereby the rigid substrate is cooled. In the case of a workpiece stuck to the protective tape, the protective tape is in close contact with the holding surface, so the protective tape is cooled by heat transfer through multiple grooves and heat conduction by the protective tape directly contacting the holding surface. Is done. Therefore, the plasma etching apparatus of the present invention can be efficiently cooled by either sticking method.

FIG. 1 is a diagram illustrating a configuration example of a plasma etching apparatus according to an embodiment. FIG. 2 is a perspective view partially showing a cross section of the electrostatic chuck table mechanism of the plasma etching apparatus according to the embodiment. FIG. 3 is a plan view of the chuck table of the electrostatic chuck table mechanism of the plasma etching apparatus according to the embodiment. FIG. 4 is an enlarged plan view showing a portion IV in FIG. FIG. 5 is a cross-sectional view showing a state in which the chuck table shown in FIG. 3 holds the workpiece adhered to the rigid substrate. FIG. 6 is a cross-sectional view showing a state in which the chuck table shown in FIG. 3 holds the workpiece adhered to the protective tape.

  DESCRIPTION OF EMBODIMENTS Embodiments (embodiments) for carrying out the present invention will be described in detail with reference to the drawings. The present invention is not limited by the contents described in the following embodiments. The constituent elements described below include those that can be easily assumed by those skilled in the art and those that are substantially the same. Furthermore, the structures described below can be combined as appropriate. Various omissions, substitutions, or changes in the configuration can be made without departing from the scope of the present invention.

Embodiment
A plasma etching apparatus according to an embodiment will be described with reference to FIGS. FIG. 1 is a diagram illustrating a configuration example of a plasma etching apparatus according to an embodiment. FIG. 2 is a perspective view partially showing a cross section of the electrostatic chuck table mechanism of the plasma etching apparatus according to the embodiment. FIG. 3 is a plan view of the chuck table of the electrostatic chuck table mechanism of the plasma etching apparatus according to the embodiment. FIG. 4 is an enlarged plan view showing a portion IV in FIG. FIG. 5 is a cross-sectional view showing a state in which the chuck table shown in FIG. 3 holds the workpiece adhered to the rigid substrate. FIG. 6 is a cross-sectional view showing a state in which the chuck table shown in FIG. 3 holds the workpiece adhered to the protective tape.

  The plasma etching apparatus 1 according to the embodiment performs a plasma etching process on the processing surface of the workpiece W. Note that the workpiece W subjected to the plasma etching process by the plasma etching apparatus 1 according to the present embodiment uses, for example, a disk-shaped semiconductor wafer or an optical device wafer whose base material is silicon, sapphire, gallium, or the like. be able to. A workpiece W is formed on each surface of the surface Wa (shown in FIG. 5 and FIG. 6) on each area partitioned by the division lines formed in a lattice pattern, and is processed as a processing surface before being divided into devices. The back surface Wb (shown in FIGS. 5 and 6) may be ground by the grinding device, and grinding distortion may remain on the back surface Wb. The workpiece W is subjected to a plasma etching process on the back surface Wb by the plasma etching apparatus 1, and the grinding distortion remaining on the back surface Wb is removed. When the workpiece W is transported to the plasma etching apparatus 1, a rigid substrate S (shown in FIG. 5) composed of a glass plate or the like that is highly rigid and does not deform is adhered to the surface Wa. A protective tape T (shown in FIG. 6) made of a synthetic resin that is easily deformed is attached.

  As shown in FIG. 1, the plasma etching apparatus 1 includes a housing 10 having a plasma processing chamber 11 and a chuck table 22 that is disposed in the plasma processing chamber 11 and holds the workpiece W by electrostatic adsorption. An electrostatic chuck table mechanism 20, a processing gas injection unit 50 that injects a processing gas for generating plasma onto the workpiece W, a decompression unit 60 that decompresses the inside of the plasma processing chamber 11, and a control unit 100 are provided.

  The housing 10 has a cylindrical shape with the upper opening closed, and forms a plasma processing chamber 11 inside. The housing 10 is provided with an opening 12 for loading and unloading the workpiece W on its side surface. A gate 13 that opens and closes the opening 12 by an air cylinder or the like is attached to the housing 10 so as to be movable in the vertical direction. The plasma processing chamber 11 is sealed when the opening 12 is closed by the gate 13.

The processing gas injection means 50 closes the lower opening of the housing 10 and supplies the processing gas supplied from the first gas supply source 51 and the second gas supply source 52 to the workpiece W held on the chuck table 22. Is to inject. As the processing gas injected by the processing gas injection means 50, a gas mainly composed of fluorine gas such as CF ₄ and SF ₆ and oxygen is used. The processing gas injection means 50 also functions as a lower electrode. The processing gas injection means 50 includes a storage container 53 provided with an injection port (not shown) for closing the lower opening of the housing 10 and injecting a processing gas, and an IPC antenna 54 stored in the storage container 53. Is housed. Terminals 54 a and 54 b of the IPC antenna 54 are connected to a high frequency power source 56. The container 53 is made of a metal such as an aluminum alloy, and is filled with a hollow body 55 such as porous ceramics. Further, the storage container 53 is formed with a discharge port 53b to which a turbo pump 57 for evacuating the storage container 53 and a dry pump 63 are connected.

  The decompression means 60 includes two exhaust ports 61 formed at the upper end of the housing 10, a turbo pump 62 and a dry pump 63 that are connected to the exhaust port 61 and evacuate the plasma processing chamber 11, and a turbo pump 62. A buffer tank 64 provided between the dry pump 63 is provided.

  The electrostatic chuck table mechanism 20 is disposed in the upper part of the housing 10 and in the plasma processing chamber 11. As shown in FIG. 2, the electrostatic chuck table mechanism 20 includes a chuck table 22 having a holding surface 21 that holds the workpiece W, and an electric charge that is provided inside the chuck table 22 and is applied with a voltage. , A power source 24 (corresponding to voltage applying means) for applying a voltage to the electrode 23, and a table base 25.

  The table base 25 also functions as an upper electrode. The table base 25 is made of a conductive metal and is connected to a high frequency power supply 26 (shown in FIG. 1). As shown in FIGS. 5 and 6, the table base 25 has the chuck table 22 disposed on the surface 25 a and is provided with cooling means 27 for cooling the chuck table 22. The cooling means 27 includes a cooling chamber 28 that is a space formed inside the table base 25, and a liquid source 30 (FIG. 1) formed in the table base 25 and via a flow rate adjusting valve 29 (shown in FIG. 1). To the water pump 32 (shown in FIG. 1) via the liquid inlet (not shown) connected to the water pump 32 (not shown), the table base 25 and the gas-liquid separation tank 31 (shown in FIG. 1), etc. And a connected gas discharge port (not shown). The cooling means 27 is supplied with a liquid (for example, pure water) from the liquid source 30 to the cooling chamber 28, and the pressure inside the cooling chamber 28 is reduced by the water pump 32. The chuck table 22 disposed on the surface 25a of the base 25 is cooled. 5 and 6 show the electrostatic chuck table mechanism 20 shown in FIG. 1 inverted.

  The chuck table 22 is disposed on the surface 25 a of the table base 25. The chuck table 22 is disposed on the surface 25 a of the table base 25, is located below the table base 25, and the holding surface 21 faces the processing gas injection means 50.

  The chuck table 22 has a workpiece W placed on the holding surface 21 and holds the workpiece W via the rigid substrate S or the protective tape T. The chuck table 10 has a disk shape formed of dielectric ceramics. When a high-voltage direct current voltage is applied from the power source 24 to the electrode 23, charges (static electricity) due to polarization are generated on the holding surface 21, and the coulomb is generated. The workpiece W is held by electrostatically attracting to the holding surface 21 by force.

  As shown in FIGS. 3 and 4, the holding surface 21 of the chuck table 22 has a groove 40 formed in a honeycomb shape in which regular hexagons are plane-filled over the entire surface and a honeycomb-shaped regular hexagonal holding surface. A plurality of convex portions 41 (shown in FIG. 4) formed to protrude from the surface 21 are provided. The groove 40 is recessed from the holding surface 21. As shown in FIG. 4, the groove 40 is formed in a honeycomb shape so that a holding surface 21 (hereinafter, denoted by reference numeral 21 a) that surrounds the inside is a regular hexagon in plan view. Only one is provided between the surfaces 21a. In the present embodiment, the groove 40 is formed in a honeycomb shape so that the length L of one side of the regular hexagonal holding surface 21a surrounded on the inside is 2.89 mm, and the width H of the groove 40 is 0.5 mm. Is formed. Further, the depth D (shown in FIGS. 5 and 6) of the groove 40 from the holding surface 21a is 5 to 10 μm. As described above, the chuck table 22 includes a number of regular hexagonal holding surfaces 21a. In the present invention, the groove 40 may be formed in a honeycomb shape so that the holding surface 21a surrounded by the groove 40 is not limited to a regular hexagon but has various figures (circle, polygon).

  The convex portion 41 is formed in a cylindrical shape, and is convex from the regular hexagonal holding surface 21a. When the rigid substrate S is placed (attached) on the holding surface 21a, the convex portion 41 forms a gap C between the regular hexagonal holding surface 21a and the rigid substrate S as shown in FIG. To do. Further, the height K (shown in FIGS. 5 and 6) of the convex portion 41 protruding from the regular hexagonal holding surface 21a is the same as that of the protective tape T attached to the surface Wa of the workpiece W in FIG. As shown, the back surface of the protective tape T is formed at a height at which the back surface of the protective tape T comes into contact with the holding surface 21a when placed in contact with the plurality of convex portions 41. In the present embodiment, the height K of the convex portion 41 from the holding surface 21a is 5 to 10 μm, and the height difference from the bottom of the groove 40 to the convex portion 41 is 10 to 15 μm. This is because the mean free path of helium molecules is 10 μm.

  In the present invention, the convex portion 41 may be formed to be convex from all the regular hexagonal holding surfaces 21a, or may not be formed to be convex from all the regular hexagonal holding surfaces 21a. In short, it is desirable that the number of convex portions 41 be as small as possible if a gap C can be formed between the rigid substrate S and the holding surface 21a. In addition, in this embodiment, it forms in the holding surface 21a of every other regular hexagon in FIG. Moreover, in this embodiment, the convex part 41 is 0.5 mm in diameter, and is formed in the center of the regular hexagonal holding surface 21a. In this invention, the convex part 41 should just be formed in the arbitrary positions of the regular hexagonal holding surface 21a.

  5 and 6, the groove 40 is provided with a plurality of injection holes 42 penetrating the chuck table 22 (note that only one injection hole 42 is shown in FIGS. 5 and 6). Shown, others omitted). The injection hole 42 communicates with a communication pipe 43 provided on the table base 25. The plasma etching apparatus 1 includes a cooling medium gas supply source 44 that communicates with at least one injection hole 42 via a communication pipe 43 and supplies a cooling medium gas into the groove 40. The cooling medium gas supplied from the cooling medium gas supply source 44 to the injection hole 42 is supplied from the injection hole 42 into the groove 40 to cool the rigid substrate S or the protective tape T, and then the plasma processing chamber in the housing 10. 11 and is discharged to the outside when the gate 13 is opened when the workpiece W is exchanged. A rare gas such as helium gas can be used as the cooling medium gas.

  The control means 100 controls each of the above-described components constituting the plasma etching apparatus 1 to cause the plasma etching apparatus 1 to perform a plasma etching process on the workpiece W. The control means 100 is mainly composed of an arithmetic processing unit constituted by, for example, a CPU or the like and a microprocessor (not shown) provided with a ROM, a RAM, etc., and a display means (not shown) for displaying the state of processing operations, images and the like. In addition, it is connected to an operating means (not shown) used when an operator registers machining content information and the like.

  Next, the processing operation of the plasma etching apparatus 1 according to the embodiment will be described. First, when the operator registers the processing content information in the control means 100 and the operator gives an instruction to start the processing operation, the plasma etching apparatus 1 starts the processing operation. When the machining operation is started, first, the control means 100 moves the gate 13 up and down to open the opening 12, and the work W is carried into the housing 10 through the opening 12 by unloading means (not shown), and the power supply 24 is turned on. The voltage is applied to the electrode 23 and the workpiece W is electrostatically adsorbed by the chuck table 22. Furthermore, the control means 100 moves the gate 13 up and down to close the opening 12.

  Next, the control unit 100 operates the turbo pumps 57 and 62 and the dry pump 63 to evacuate the inside of the plasma processing chamber 11 and the storage container 53 in the housing 10. In addition, the control means 100 operates the water pump 32 to exhaust the cooling chamber 28 in the table base 25 and reduce the pressure almost simultaneously with the vacuum exhaust in the plasma processing chamber 11 and the storage container 53 in the housing 10. Then, the liquid in the cooling chamber 28 supplied from the liquid source 30 is nucleate boiled to cool the chuck table 22 disposed on the surface 25a of the table base 25. Further, the control means 100 supplies the cooling medium gas into the groove 40 from the cooling medium gas supply source 44 almost simultaneously with the evacuation of the plasma processing chamber 11 and the storage container 53 in the housing 10, and the chuck table 22. And the workpiece W is cooled.

  At this time, when the protective tape T is affixed to the surface Wa contacting the holding surface 21a of the workpiece W, the protective tape T is deformed by the electrostatic adsorption force of the chuck table 22, and as shown in FIG. Further, the protective tape T is placed in contact with the holding surface 21a excluding the convex portion 41 and the vicinity of the convex portion 41. Then, the protective tape T enters the fine unevenness provided on the holding surface 21a to some extent by the electrostatic attraction force of the chuck table 22, and the back surface of the protective tape T and the holding surface 21a of the chuck table 22 come into contact with each other for cooling. The temperature of the means 27 is thermally conducted as indicated by an arrow indicated by a dotted line in FIG. 6, and the entire protective tape T is cooled by the heat conduction from the protective tape T to the cooling means 27. Furthermore, since the convex portion 41 is in a state of being cut into the protective tape T, the cooling medium gas supplied from the groove 40 is jetted onto the protective tape T, and the temperature of the cooling medium gas is indicated by an arrow indicated by a dotted line in FIG. Thus, the entire protective tape T is cooled by the heat transfer by the cooling medium gas.

  In addition, when the rigid substrate S is attached to the surface Wa that is in contact with the holding surface 21a of the workpiece W, a plurality of rigid substrates S are provided by the electrostatic adsorption force of the chuck table 22 as shown in FIG. It is placed in contact with the convex portion 41. A slight gap C is generated between the back surface of the rigid substrate S and the holding surface 21 a of the chuck table 22. The cooling medium gas supplied from the groove 40 flows as indicated by an arrow indicated by a solid line in FIG. 5, spreads in the gap C, and the temperature of the cooling medium gas is transferred as indicated by an arrow indicated by a dotted line in FIG. 5. Thus, the entire rigid substrate S is cooled by heat transfer. Further, since the rigid substrate S is placed in contact with the plurality of convex portions 41, the temperature of the cooling means 27 is thermally conducted as indicated by the dotted line in FIG. The entire rigid substrate S is cooled by heat conduction.

  When the pressure in the plasma processing chamber 11 of the housing 10 is reduced to a predetermined pressure and the chuck table 22 is cooled to a predetermined temperature by the nucleate boiling of the liquid in the cooling chamber 28 of the table base 25, plasma etching is performed. Preparation for processing is completed.

  After the preparation for the plasma etching process is completed, the control means 100 operates the high frequency power supply 26 to apply a predetermined frequency and a predetermined output power to the table base 25 as the upper electrode. At the same time, the control means 100 operates the high-frequency power source 56 to apply power of a predetermined frequency and a predetermined output to the IPC antenna 54 via the terminals 54a and 54b. Further, the control means 100 starts the supply of the processing gas by operating the first gas supply source 51 and the second gas supply source 52 simultaneously with the operation of the high frequency power supply 26. The processing gas supplied from the first gas supply source 51 and the second gas supply source 52 is injected from the injection port of the storage container 53 onto the workpiece W held on the chuck table 22.

  At this time, since electric power is applied from the high-frequency power source 56 to the IPC antenna 54, the injected processing gas is turned into plasma by the IPC antenna 54 and is supplied from the processing gas injection means 50 to the plasma processing chamber 11 in the housing 10. The plasma etching process is performed on the back surface Wb of the workpiece W by being injected. When the plasma etching process is performed on the back surface Wb of the workpiece W for a predetermined time, the control unit 100 appropriately stops the components of the plasma etching apparatus 1 and opens the workpiece W having the plasma etching process applied to the back surface Wb. 12, the workpiece W before the plasma etching process is carried into the housing 10 and plasma etching is performed in the same process as before.

  As described above, according to the plasma etching apparatus 1 according to the embodiment, since the plurality of grooves 40 and the plurality of convex portions 41 are formed on the holding surfaces 21 and 21a that hold the workpiece W, the plasma etching apparatus 1 is attached to the rigid substrate S. In the case of the attached workpiece W, the convex portion 41 forms a gap C between the holding surfaces 21 and 21a and the cooling medium gas is supplied to the gap C, whereby the entire rigid substrate S is cooled. . Further, in the case of the workpiece W adhered to the protective tape T, the protective tape T comes into contact with the holding surfaces 21 and 21a. Therefore, the heat generated by the cooling medium gas sprayed from the plurality of grooves 40 by the protective tape T. The entire surface of the protective tape T is cooled by the transmission and the heat conduction of the cooling means 27 when the protective tape T directly contacts the holding surfaces 21 and 21a. Therefore, the plasma etching apparatus 1 can be efficiently cooled regardless of the method of attaching the protective tape T or the rigid substrate S. Moreover, since the plasma etching apparatus 1 can be efficiently cooled by any of the attachment methods of the protective tape T and the rigid substrate S, the workpiece W adhered to the protective tape T and the rigid substrate S Even if the workpiece W adhered to the substrate is changed, it is not necessary to replace the chuck table 22 or the like, so that it is possible to suppress a decrease in productivity.

  The present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Plasma etching apparatus 10 Housing 11 Plasma processing chamber 20 Electrostatic chuck table mechanism 21, 21a Holding surface 22 Chuck table 23 Electrode 24 Power supply (voltage application means)
25 Table base 25a Surface 27 Cooling means 40 Groove 41 Convex part 50 Process gas injection means 60 Decompression means W Workpiece K Height

Claims (1)

An electrostatic chuck table mechanism including a housing having a plasma processing chamber, a chuck table for holding a workpiece by electrostatic adsorption on a holding surface disposed in the plasma processing chamber of the housing, and held by the chuck table A plasma etching apparatus comprising: a processing gas injection unit that injects a processing gas for generating plasma into the processed workpiece; and a decompression unit that depressurizes the plasma processing chamber,
The electrostatic chuck table mechanism includes a chuck table having a holding surface for holding a workpiece, an electrode disposed inside the chuck table and generating an electric charge when a voltage is applied thereto, and a voltage applied to the electrode. A voltage applying means for applying a voltage, and a table base provided with a cooling means for disposing the chuck table on the surface and cooling the chuck table inside,
The holding surface of the chuck table has grooves formed in a honeycomb shape in which regular hexagons are plane-filled over the entire surface, and a plurality of protrusions formed to protrude from the honeycomb-shaped regular hexagonal holding surface. With
The groove has a plurality of injection holes, and includes a cooling medium gas supply source that communicates with the injection holes and supplies a cooling medium gas into the groove.
The height of each convex portion protruding from the holding surface is such that when the protective tape attached to the surface of the workpiece is placed in contact with the plurality of convex portions, the rear surface of the protective tape. Is formed at a height that contacts the holding surface,
When the protective tape is affixed to the surface of the workpiece that contacts the holding surface, the protective tape is placed in contact with the plurality of convex portions and the holding surface, and the back surface of the protective tape. And the holding surface of the chuck table are in contact with each other, the entire protective tape is cooled by heat conduction to the cooling means and heat transfer by the cooling medium gas supplied from the groove,
When the rigid substrate is attached to the surface of the workpiece that contacts the holding surface, the rigid substrate is placed in contact with the plurality of convex portions, and the back surface of the rigid substrate and the chuck table A slight gap is formed between the holding surface, the cooling medium gas supplied from the groove spreads over the gap, and the entire rigid substrate is cooled by heat transfer.
A plasma etching apparatus.

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