JP5508737B2 - Electrostatic chuck and plasma processing apparatus - Google Patents

Description

  The present invention relates to an electrostatic chuck for attracting and fixing a substrate to be processed by electrostatic force, and a plasma processing apparatus using the electrostatic chuck.

  For example, in the manufacture of flat panel display (FPD) panels, pixel devices or electrodes, wirings and the like are generally formed on a substrate made of an insulator such as glass. Among various processes of panel manufacture, plasma is used in fine processing such as etching, CVD, ashing, and sputtering. In a manufacturing apparatus that performs such plasma processing, a substrate is placed on a mounting table (or a sample table) in a processing container that can be depressurized, and the upper surface (surface to be processed) of the substrate is exposed to processing gas plasma. Processing is performed. In this case, it is necessary to control the temperature of the substrate to be constant while suppressing the temperature rise due to heat input from the plasma. For this reason, the coolant temperature-controlled by the chiller device is circulated and supplied to the coolant passage in the mounting table. A method of indirectly cooling the substrate by supplying a heat transfer gas such as He gas to the back surface of the substrate through the mounting table is often used. This cooling method requires a holding mechanism for fixing the substrate on the mounting table against the supply pressure of the heat transfer gas, and an electrostatic chuck is often used as such a holding mechanism.

  In an electrostatic chuck, typically, a dielectric layer having an electrode enclosed therein is provided on the upper surface (mounting surface) of the mounting table, a predetermined DC voltage is applied to the electrode, and the substrate and the dielectric layer are separated from each other. The substrate is attracted by the electrostatic attracting force generated between them.

There are two types of electrostatic chuck electrode forms or voltage application, a monopolar type and a bipolar type. In the monopolar type, a single or unipolar electrode is provided inside a dielectric layer, and a constant potential difference is applied between the electrode and the substrate. In the bipolar type, a plurality of or bipolar electrodes are provided inside a dielectric layer, and a positive or negative voltage is applied to each electrode. Generally, ceramics such as Al ₂ O ₃ having high plasma resistance are often used for the dielectric layer of the electrostatic chuck.

JP 2005-136350 A

  By the way, the panel substrate is steadily increasing in size. For example, the size of the substrate (mother glass) is about 2200 × 2600 mm in the eighth generation which is currently mainstream in liquid crystal panels. Corresponding to such an increase in the size of the substrate, the mounting table and the electrostatic chuck of the plasma processing apparatus are also increased. For example, the size of 2250 × 2650 mm is required for the eighth generation.

  The problem here is the high cost of the electrostatic chuck, and in particular, the ceramics used for the dielectric layer are the main factor of the high cost. Ceramics for electrostatic chucks are high-purity products with excellent plasma resistance, are very expensive, and cost increases in proportion to the area. Therefore, with the shift from the seventh generation (1870 × 2200 mm) of the liquid crystal panel to the eighth generation, the size (area) of the electrostatic chuck has also increased by about 1.4 times, and the cost of ceramics and thus the cost of the electrostatic chuck Has risen by nearly 40%.

  The 9th generation (2400 × 2800 mm) and the 10th generation (2850 × 3050 mm) are also scheduled in the near future, and the above problems are becoming more serious.

  The present invention has been made in view of the above-described problems of the prior art. An electrostatic chuck that achieves both low cost and durability against an increase in the size of a substrate to be processed and a plasma processing apparatus including the electrostatic chuck are provided. The purpose is to provide.

  Furthermore, an object of the present invention is to provide an electrostatic chuck excellent in maintainability and maintenance cost and a plasma processing apparatus including the same.

In order to achieve the above object, an electrostatic chuck of the present invention is an electrostatic chuck for adsorbing a substrate to be processed by an electrostatic force in a processing container that can be depressurized and holding it on a mounting table. A first dielectric layer disposed on an inner side of an outer peripheral edge of the substrate on a mounting surface of the mounting table and made of a resin; and a first electrode provided inside the first dielectric layer; A first electrostatic attracting portion having a first dielectric attracting portion, a second dielectric layer made of ceramics disposed around the first electrostatic attracting portion so as to surround the first electrostatic attracting portion on the mounting surface of the mounting table, and the first A second electrostatic attraction unit having a second electrode provided inside the two dielectric layers, and a direct current power source for individually and simultaneously applying independent direct current voltages to the first and second electrodes. On the mounting surface of the mounting table, the outer peripheral edge of the first electrostatic attraction portion is the front Located from the outer edge of the substrate to the inner or Debye length of the plasma generated in the processing chamber, the outer peripheral edge of the second electrostatic chuck portion is located outside the outer circumference edge of the substrate.

In the above configuration, the first electrostatic attraction unit is disposed in a region inside the outer peripheral edge of the substrate on the mounting surface of the mounting table, and the first electrode to which a DC voltage is applied from the DC power source and the first electrode The substrate is adsorbed by using an electrostatic attraction force (Johnson-Rahbek force, Coulomb force or gradient force) by an electrostatic induction function with the first dielectric layer enclosing the first electrode. The first electrostatic attraction part has an outer peripheral edge located on the inner side of the outer peripheral edge of the substrate, a lower surface is covered with the mounting table, an upper surface is covered with the substrate, and a side surface is covered with the second electrostatic attraction part. Therefore, it is not directly exposed to the atmosphere in the processing container. As a result, even if the resin constituting the first dielectric layer of the first electrostatic attraction portion is easily deteriorated in the atmosphere in the processing vessel, particularly in plasma, the apparent atmospheric resistance is high. As a result, it is difficult to deteriorate. On the other hand, the second electrostatic attraction unit is arranged around the first electrostatic attraction unit so as to surround the first electrostatic attraction unit, and the second electrode to which a DC voltage is applied from a DC power source and the second electrode are connected. The substrate is adsorbed by using an electrostatic attraction force (Johnson-Rahbek force, Coulomb force, or gradient force) by an electrostatic induction function with the enclosed second dielectric layer. Second electrostatic adsorption unit, the outer peripheral edge of its is positioned outside the outer peripheral edge of the substrate, but is directly exposed to the atmosphere of the processing vessel in place of the first electrostatic adsorption unit, the second static Since the ceramic constituting the second dielectric layer of the electroadsorption portion is much more durable than the resin in a normal process atmosphere (typically plasma), it is also hardly deteriorated. Therefore, the entire electrostatic chuck can have the same durability as when the entire dielectric layer is made of ceramics.
Further, in the present invention, since independent DC voltages are simultaneously applied to the first electrode provided in the first electrostatic adsorption unit and the second electrode provided in the second electrostatic adsorption unit, For example, even for a large substrate for FPD, the electrostatic adsorption force can be exerted uniformly on the entire substrate, and the substrate can be stably held on the mounting table against the supply pressure of the heat transfer gas.

  In terms of cost, the configuration in which the first electrostatic attraction portion has the first dielectric layer made of resin can significantly reduce the cost compared to the case of ceramics. In addition, since the first electrostatic attraction part generally occupies a larger area than the second electrostatic attraction part, a significant cost reduction can be realized for the entire electrostatic chuck.

  Further, in the present invention, the first electrostatic attraction unit includes a plurality of first electrostatic attraction blocks divided in a one-dimensional direction or a two-dimensional direction on the mounting surface of the mounting table. A configuration in which one electrostatic attraction block has a first dielectric layer and a first electrode independent for each block is suitably employed. In this case, preferably, m × n (m and n are natural numbers) first electrostatic adsorption blocks are arranged in m rows × n columns, and m × n provided in each of the first electrostatic adsorption blocks. The first electrodes are electrically connected to the DC power supply in parallel. Further, in order to detect a dielectric breakdown in the first electrostatic attraction portion, a switch circuit for electrically connecting the m × n first electrodes to the DC power source in units of rows or columns, and a DC power source A configuration having an ammeter connected between the output terminal and the first electrode or between the first electrode and the reference voltage terminal is suitably employed.

  Further, in the present invention, the second electrostatic attraction unit includes a plurality of second electrostatic attraction blocks divided in a one-dimensional direction or a two-dimensional direction on the mounting surface of the mounting table. A configuration in which the two electrostatic adsorption blocks have a second dielectric layer and a second electrode independent for each block is suitably employed.

Further, in the present invention, the substrate is subjected to plasma processing in the processing container, and the outer peripheral edge of the first electrostatic attraction portion on the mounting surface of the mounting table is a distance greater than or equal to the plasma Debye length from the outer peripheral edge of the substrate A configuration is adopted that is located on the inside with a gap therebetween. Ri by the above configuration, it is possible to first electrostatic adsorption unit is reliably prevented may be exposed to plasma.

  Moreover, in the suitable one aspect | mode of this invention, the structure which the outer periphery edge of a 1st electrostatic attraction part is located outside the element formation area of a board | substrate on the mounting surface of a mounting base is taken. In this configuration, the element forming region of the substrate can be adsorbed with a constant adsorbing force exclusively through the first electrostatic adsorbing portion, and the temperature can be controlled stably.

  In a preferred aspect of the present invention, the first electrostatic attraction unit has a first gas hole through which a heat transfer gas for thermally coupling the mounting table and the substrate is passed, and the second The electrostatic adsorption unit has a second gas hole through which a heat transfer gas for thermally coupling the mounting table and the substrate is passed.

For the second dielectric layer of the second electrostatic attraction portion, for example, a ceramic containing aluminum oxide, aluminum nitride, or silicon carbide can be suitably used.

Further, as the resin constituting the first dielectric layer of the first electrostatic adsorption unit, among the resin durability, it is preferably one excellent in pairs chemical resistance and heat resistance, for example, polyimide can be preferably used.

  The plasma processing apparatus of the present invention includes a processing container capable of depressurization, a mounting table for mounting a substrate to be processed in the processing container, and a plasma generator for generating plasma of processing gas in the processing container And the electrostatic chuck of the present invention for adsorbing the substrate by electrostatic force and holding it on the mounting table.

  The present invention has the above-described configuration and operation, and achieves both low cost and durability against an increase in the size of the substrate to be processed, and further provides an electrostatic chuck excellent in maintainability and maintenance cost. Can be obtained.

It is sectional drawing which shows the structure of the plasma processing apparatus in one Embodiment of this invention. It is a top view which shows the structure of the electrostatic chuck in embodiment. It is a schematic sectional drawing which shows the structure of the edge part of the electrostatic chuck in embodiment. It is a schematic sectional drawing which shows typically the gas supply system and DC electric power feeding system inside a susceptor in embodiment. It is sectional drawing which shows the structure of the electrostatic adsorption block which comprises the center electrostatic adsorption part of the electrostatic chuck in embodiment. It is a top view which shows the structure of the said electrostatic adsorption block. It is a top view which shows the example of a layout of the DC electrode in the said electrostatic adsorption block. It is sectional drawing which shows the structure of the electrostatic adsorption block which comprises the periphery electrostatic adsorption part of the electrostatic chuck in embodiment. It is a top view which shows the structure of the said electrostatic adsorption block. It is a circuit diagram which shows one Example of the test | inspection circuit for detecting the electrostatic adsorption block which has produced the dielectric breakdown in embodiment. It is a circuit diagram which shows another Example of a test | inspection circuit.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 shows the configuration of a plasma processing apparatus according to an embodiment of the present invention. This plasma processing apparatus is configured as a capacitively coupled plasma etching apparatus having a rectangular glass substrate G for FPD as a substrate to be processed, for example, and can be decompressed in a rectangular tube shape made of aluminum whose surface is anodized. The chamber (processing container) 10 is provided. A rectangular susceptor (mounting table) 14 is installed on the bottom surface of the chamber 10 via an insulating plate or insulating sheet 12. The chamber 10 is grounded for safety.

  The susceptor 14 is made of aluminum, for example, and also serves as a lower electrode. For example, a high frequency power supply 16 that outputs a high frequency of 13.56 MHz is electrically connected to the susceptor 14 via a matching unit (M) 18.

  Above the susceptor 14, a shower head 20, which also serves as an upper electrode, is provided in parallel with the susceptor 14. The shower head 20 is attached to the ceiling of the chamber 10, and a buffer chamber 20 a is formed inside the head 10, and a plurality of ejection holes 20 b for discharging a processing gas are formed on the lower surface of the head facing the susceptor 14. Yes. A gas introduction port 22 is provided on the upper surface of the shower head 20, and a gas supply pipe 26 from the processing gas supply unit 24 is connected to the gas introduction port 22. The shower head 20 is electrically grounded, and constitutes a pair of parallel plate electrodes with the susceptor 12.

  An electrostatic chuck 30 is provided on the upper surface (mounting surface) of the susceptor 14 for attracting and holding the substrate G by electrostatic force. As a basic form, the electrostatic chuck 30 includes a dielectric layer 32 in which a plate-like or film-like DC (direct current) electrode 34 is enclosed, and the DC electrode 34 disposed outside the chamber 10 has a DC shape. A high voltage, for example, a DC voltage of 1 to 5 kV is applied from the power source 36. Between the DC electrode 34 and the DC power source 36, a circuit, for example, a low-pass filter (F) 38 for cutting off a leakage high frequency coming from the susceptor 14 is provided. There is also provided a changeover switch 40 for switching the potential of the DC electrode 34 to either the output voltage of the DC power supply 34 or the ground potential.

  A configuration in which the high frequency from the high frequency power supply 16 and the DC voltage from the DC electrode 34 are combined or superimposed and introduced into the susceptor 14 or the DC electrode 34 is also possible.

  A coolant channel 42 is provided inside the susceptor 14, and a temperature-controlled coolant from a chiller device (not shown) flows through the coolant channel 42. The susceptor 14 is formed with a large number of gas flow paths 44 opened on the mounting surface thereof, and the electrostatic chuck 30 has a large number of through holes or gas holes (not shown) connected to the gas flow paths 44 of the susceptor 14. ) Is provided. A heat transfer gas such as He gas from the heat transfer gas supply unit 46 is supplied to the back surface of the glass substrate G at a predetermined pressure through the gas flow path 44 of the susceptor 14 and the gas hole of the electrostatic chuck 30. Yes.

  The outer peripheral edge of the upper surface (mounting surface) of the susceptor 14, that is, the portion around the substrate G and the side surface of the susceptor 14 are covered with a dielectric cover or focus ring 47 made of, for example, quartz.

  An exhaust mechanism 50 having a vacuum pump (not shown) is connected to an exhaust port provided at the bottom of the chamber 10 via an exhaust pipe 48. The interior of the chamber 10 is exhausted by the exhaust mechanism 50, and the interior of the chamber 10 is maintained at a predetermined vacuum pressure during the plasma processing. A substrate loading / unloading port is formed on the side wall of the chamber 10, and the substrate loading / unloading port can be opened and closed by a gate valve 52.

  The control unit 54 may be constituted by a microcomputer, and each part of the plasma etching apparatus, that is, the high frequency power source 18, the processing gas supply unit 24, the DC power source 36, the switch 40, the heat transfer gas supply unit 46, the exhaust mechanism 50, and the like are individually provided. And the operation sequence of the entire apparatus is controlled.

  In this plasma etching apparatus, in order to perform plasma etching, first, the gate valve 52 is opened, and the glass substrate G to be processed is loaded into the chamber 10 and placed on the electrostatic chuck 30. A predetermined DC voltage is applied from the DC power source 36 to the DC electrode 34 of the electrostatic chuck 30, and the electrostatic chuck 30 applies the glass substrate G to the electrostatic chucking force (Johnson-Rahbek force, Coulomb force, or gradient force). Secure on top. Then, a processing gas, that is, an etching gas (generally a mixed gas) is introduced into the chamber 10 from the processing gas supply unit 24 at a predetermined flow rate and flow rate ratio, and the inside of the chamber 10 is set to a set pressure by the exhaust mechanism 50. Further, He gas is supplied from the heat transfer gas supply unit 46 to the back surface of the substrate G through the gas flow path 42 of the susceptor 14 and the gas holes of the electrostatic chuck 30. Further, a high frequency is applied to the susceptor 14 with a predetermined power from the high frequency power supply 16. The etching gas discharged from the shower head 20 is discharged between the electrodes 14 and 20 to generate plasma, and radicals and ions in the plasma react with the film to be etched through the etching mask on the surface of the glass substrate G to be etched. The film is etched into the desired pattern.

  In the plasma etching apparatus, the present invention can be applied to the electrostatic chuck 30. Hereinafter, the configuration and operation of the electrostatic chuck 30 according to the embodiment of the present invention will be described in detail with reference to FIGS.

  As shown in FIG. 2, the electrostatic chuck 30 according to the present invention is located on the placement surface of the susceptor 14 (FIG. 1) on the inner side of the outer edge of the substrate G with respect to the substrate G placed thereon. A central electrostatic attraction unit 60 disposed in the area and a peripheral electrostatic attraction unit 62 disposed around the central electrostatic attraction unit 60 so as to surround the central electrostatic attraction unit 60. Here, the central electrostatic attraction unit 60 and the peripheral electrostatic attraction unit 62 may be arranged in close contact with each other without a gap, but may be arranged with a little gap therebetween.

  The main difference between the central electrostatic chuck 60 and the peripheral electrostatic chuck 62 is the material of the dielectric layer 32 (FIG. 1). That is, the central electrostatic attraction part 60 has a dielectric layer 32A made of resin (FIG. 5), and the peripheral electrostatic attraction part 62 has a dielectric layer 32B made of ceramics (FIG. 8).

  The central electrostatic attraction unit 60 is composed of 42 rectangular electrostatic attraction blocks 64 divided into a plurality of, for example, 7 rows × 6 columns matrix. These electrostatic attraction blocks 64 are preferably in close contact with each other and may be arranged with no gap, but may be arranged with a little gap. Each electrostatic adsorption block 64 may be fixed to the susceptor 14 with an adhesive, but may preferably be detachably attached to each block by a bolt or the like.

  The peripheral electrostatic chuck 62 includes a plurality of, for example, 30 rectangular electrostatic chuck blocks 66 arranged in a line along the outer periphery of the central electrostatic chuck 62. These electrostatic adsorption blocks 66 may also be arranged in close contact with each other without any gaps, but may be arranged with a little gap therebetween. In addition, each electrostatic adsorption block 66 may be fixed to the susceptor 14 with an adhesive or the like, but may preferably be detachably attached to each block by a bolt or the like.

  In the illustrated example, the electrostatic adsorption block 64 of the central electrostatic adsorption unit 60 and the electrostatic adsorption block 66 of the peripheral electrostatic adsorption unit 62 are formed in the same shape and the same size. For example, when the substrate G is the eighth generation of the liquid crystal panel and the size of the electrostatic chuck 30 is 2250 × 2650 mm, the size of the electrostatic adsorption blocks 64 and 66 may be selected to be about 281 × 295 mm.

In this embodiment, the configuration in which the central electrostatic attraction unit 60 is arranged on the inner side of the outer peripheral edge of the substrate G on the susceptor 14 is important and essential. Among these, as shown in FIG. 3, the outer peripheral edge 60e of the central electrostatic chuck 60 is located on the inner side with a distance equal to or greater than the plasma Debye length λ _D from the outer peripheral edge Ge of the substrate G. A configuration located outside the G element formation region (that is, a configuration located within the range M in FIG. 3) is particularly preferable.

That is, the cost of the central electrostatic attraction part 60 having the dielectric layer 32A made of resin is very low, and is 1/10 or less of the cost of the peripheral electrostatic attraction part 62 having the dielectric layer 32B made of ceramics. Therefore, as the area occupied by the central electrostatic attraction unit 60 in the electrostatic chuck 30 is increased, the cost of the entire electrostatic chuck 30 is reduced. However, if the outer peripheral edge 60e of the central electrostatic attraction unit 60 is close to the outer peripheral edge Ge of the substrate G on the susceptor 14 by a distance equal to or less than the Debye length λ _{D, the} plasma generated in the chamber 10 is the back surface of the substrate G. And the electrostatic chuck 30 may reach the central electrostatic chuck 60. Then, the resin dielectric layer 32A in the vicinity of the outer peripheral edge 60e of the central electrostatic attraction part 60 is easily exposed to plasma and deteriorates.

The Debye length λ _{D of} plasma is represented by λ _D = (ε ₀ · k _{B Te} / N _e e ² ) ^1/2 . Here, ε ₀ is the dielectric constant in vacuum, k _B is the Boltzmann constant, _Te is the electron temperature of the plasma, N _e is the electron density of the plasma, and e is the charge of the electrons. The Debye length λ _{D of} plasma used for normal plasma processing is several mm or less.

  On the other hand, excessively reducing the area occupied by the central electrostatic chuck 60 in the electrostatic chuck 30 is undesirable not only in terms of cost but also in terms of process. That is, since there are usually differences in the attractive force and interface characteristics (especially heat transfer characteristics) of the central electrostatic attracting part 60 and the peripheral electrostatic attracting part 62 with respect to the substrate G, an element formation region or product of the substrate G It is not preferable that the central electrostatic attraction part 60 and the peripheral electrostatic attraction part 62 coexist in the region. In general, the element formation region of the substrate G is set several cm inside the outer peripheral edge Ge.

  FIG. 4 schematically shows a gas supply system and a DC power supply system inside the susceptor 14. In the gas supply system, a heat transfer gas port 70 for introducing He gas is provided on the lower surface of the susceptor 14, and each of the central electrostatic adsorption unit 60 and the peripheral electrostatic adsorption unit 62 is provided from the heat transfer gas port 70. A gas flow path 44 extending to the gas holes 72A and 72B is formed in the susceptor 14. In this embodiment, each electrostatic adsorption block 64, 66 of the central electrostatic adsorption unit 60 and the peripheral electrostatic adsorption unit 62 has one or a plurality of gas holes 72A, 72B for each block.

Further, on the lower surface of the susceptor 14, connectors 74A ₁ , 74A ₂ , and 74B that are electrically connected to a DC power supply conductor such as a covered wire (not shown) from the DC power source 36 are provided. In this embodiment, the central electrostatic attraction unit 60 is configured as a bipolar type, and the peripheral electrostatic attraction unit 62 is configured as a monopolar type. The central electrostatic attraction unit 60 has two DC voltages V _A1 , V _A2 is supplied with power through the connectors 74A ₁ and 74A ₂ , and a single DC voltage V _B is supplied to the peripheral electrostatic attraction portion 62 through the connector 74B. One of the DC voltages V _A1 and V _A2 may be a ground potential (0 volt). It is also possible to configure the central electrostatic attraction unit 60 as a monopolar type and the peripheral electrostatic attraction unit 62 as a bipolar type, which is common to the central electrostatic attraction unit 60 and the peripheral electrostatic attraction unit 62. A DC voltage may be applied.

Inside the susceptor 14, the covered conductors 78A ₁ and 78A ₂ extend from the connectors 74A ₁ and 74A ₂ to the terminals T _A1 and T _A2 (FIG. 5) of the bipolar DC electrodes 76A ₁ and 76A ₂ of the central electrostatic chuck 60. And a covered conductor 78B extending from the connector 74B to the terminal T _B (FIG. 5) of the unipolar DC electrode 76B of the peripheral electrostatic attraction portion 62 is wired.

5 to 7 show the configuration of the electrostatic adsorption block 64 of the central electrostatic adsorption unit 60. FIG. 5 and 6 are a cross-sectional view and a plan view of the electrostatic adsorption block 64, respectively. FIG. 7 is a diagram showing a layout of the bipolar DC electrodes 34A ₁ and 34A ₂ provided in the electrostatic adsorption block 64.

Dielectric layer 32A of the electrostatic adsorption block 64, as shown in FIG. 5, an upper dielectric layer 32A _U and the laminated structure of the lower dielectric layer 32A _L made of a film of resin having high e.g. polyimide heat resistance, both dielectric layers 32A _U, which is N interpolation of DC electrodes 34A _1, 34A ₂ bipolar consisting of copper foil or conductive film for example, between the 32A _L. These bipolar DC electrodes 34A ₁ and 34A ₂ are, for example, formed in a comb shape as shown in FIG.

The upper surface of the upper dielectric layer 32A _U, as shown in FIGS. 5 and 6, for example, a cylindrical protrusion 80 formed by embossing is provided discretely number. On the electrostatic chuck 30, the back surface of the substrate G is in close contact with the protrusion 80, and comes into contact with He gas in a recess (dimple) region other than the protrusion 80. The shape of the protrusion 80 is not limited to a cylindrical shape, and may be, for example, a prismatic shape or a hemispherical shape.

  8 and 9 show the configuration of the electrostatic adsorption block 66 of the peripheral electrostatic adsorption unit 62. FIG. 5 and 6 are a cross-sectional view and a plan view of the electrostatic adsorption block 66, respectively.

As shown in FIG. 8, the dielectric layer 32B of the electrostatic adsorption block 66 includes an upper dielectric layer 32B made of ceramics such as alumina, aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), or silicon carbide (SiC). It has a laminated structure of _U and the lower dielectric layer 32B _L, both the dielectric layer 32B _U, and Nde inserted a monopolar DC electrode 34B made of, for example, conductive paste during 32B _L, for example by a green sheet printing lamination method Produced. In addition, zirconia (ZrO ₂ ) can also be suitably used as the ceramic material.

Also in electrostatic attraction block 66, as shown in FIGS. 8 and 9, a cylindrical projection 82 may be provided discretely number on the upper surface of the upper dielectric layer 32B _U. On the electrostatic chuck 30, the back surface of the substrate G is in close contact with the protrusion 82, and comes into contact with He gas in a recessed area other than the protrusion 82. Further, the peripheral portion 84 of the upper surface of the upper dielectric layer 32B _U is formed into a flat surface, the outer peripheral edge Ge of the substrate G thereon is made to rest in close contact. Thus, the He gas is prevented from leaking out from the outer peripheral edge Ge of the substrate G.

  9 constitutes a side portion of the electrostatic chuck 30 and the flat peripheral edge portion 84 is formed in a straight line. In the electrostatic attraction block 66 that constitutes the corner of the electrostatic chuck 30, the flat peripheral edge 84 is formed in an L shape. That is, the shaded area 86 in FIG.

  As described above, the electrostatic chuck 30 in this embodiment is substantially the same shape as the substrate G placed on the susceptor 14 and has a size that is slightly larger than the outer periphery edge of the substrate G. And a peripheral electrostatic attraction portion 60 having a dielectric layer 32B made of ceramics and a dielectric layer 32B made of ceramics. Part 62.

  In such a hybrid electrostatic chuck structure, the dielectric layer 32A of the central electrostatic attraction portion 60 is made of resin, and thus is originally a substrate having low plasma resistance. However, since the central electrostatic attraction unit 60 is completely hidden under the substrate G when the substrate G is adsorbed, it is not exposed to the plasma during the plasma processing, and is therefore used many times in the plasma process. However, the resin dielectric layer 32A is less likely to deteriorate.

  On the other hand, since the peripheral electrostatic attraction portion 62 protrudes from the outer peripheral edge Ge of the substrate G on the mounting surface of the susceptor 14, it is exposed to the plasma during the plasma processing, but the dielectric layer 32B is plasma resistant. Since it is made of high ceramics, it has a structure that does not easily deteriorate even if it is used many times in the plasma process.

  As described above, the center electrostatic attracting unit 60 and the peripheral electrostatic attracting unit 62 are configured to sufficiently withstand the plasma process as a result even though there is an apparent or substantial difference. Thereby, the electrostatic chuck 30 can have durability equivalent to the case where the entire dielectric layer 32 is made of ceramics.

  In terms of cost, the ratio of the area occupied by the central electrostatic chuck 60 and the peripheral electrostatic chuck 62 in the electrostatic chuck 30 is the area of the resin dielectric layer 32A and the ceramic dielectric layer 32B as they are. The ratio is reflected in the overall cost of the electrostatic chuck 30. For example, in the configuration example shown in FIG. 2, the area ratio of the central electrostatic chuck 60 and the peripheral electrostatic chuck 62 is 42:30, and the central electrostatic chuck 60 occupies about 60% of the whole. That is, about 60% of ceramics are replaced with resin whose cost is 1/10 or less as compared with the case where the entire dielectric layer 32 is made of ceramics. As a result, the overall cost of the electrostatic chuck 30 can be significantly reduced (for example, to a fraction or less).

  Further, in this embodiment, electrostatic chuck blocks 64 and 66 having independent dielectric layers (32A and 32B) and DC electrodes (34A and 34B) for each block are laid in a one-dimensional direction or a two-dimensional direction so that the center static The electroadhesion part 60 and the peripheral electrostatic adsorption part 62 are comprised. Such a modular electrostatic chuck structure is excellent in versatility because the size of the electrostatic chuck can be freely changed in accordance with the size of the substrate G. For example, it is easy for the ninth generation and the tenth generation of FPD panels. It can correspond to.

  Further, when a failure occurs in any one of the electrostatic adsorption blocks 64 and 66, particularly when the polarization performance of the dielectric layer 32 is deteriorated due to a change with time or the like, the electrostatic adsorption block 64, which has a poor insulation. Only 66 has to be replaced, and the entire electrostatic chuck is not required to be replaced. Therefore, there is an advantage that the maintenance cost can be significantly reduced.

  FIG. 10 and FIG. 11 show an example of an inspection circuit for detecting the electrostatic adsorption blocks 64 and 66 that have caused the dielectric breakdown in this embodiment. In order to simplify the explanation and illustration, the electrostatic adsorption block 66 of the peripheral electrostatic adsorption unit 62 is omitted, and the electrostatic adsorption block 64 of the central electrostatic adsorption unit 60 is arranged in a matrix of 4 rows × 4 columns. An example of arrangement will be described.

  The inspection circuit of FIG. 10 is a case where the electrostatic chucking block 64 is configured as a single pole type, and has a function of detecting the electrostatic chucking block 64 in which dielectric breakdown has occurred, for example, in units of rows. More specifically, the on / off switch 86 is connected in series with the DC electrode 34 of the electrostatic adsorption blocks 64 (i, 1) to 64 (i, 4) (where i = 1, 2, 3, 4) of each row. (1) to 86 (4) are connected, and the changeover switch 40 and the ammeter 85 are connected in parallel between the DC power source 36 and the on / off switches 86 (1) to 86 (4).

  The on / off switches 86 (1) to 86 (4) are all kept in the on state during the steady state, particularly during the plasma processing, and the DC voltage from the DC power source 36 is applied to the DC electrodes 34 of each row. Supply power. However, when this inspection circuit is used, one of the on / off switches 86 (1) to 86 (4) is selectively turned on at a time, and the others are kept off. It has become.

  The on / off switch 88 is in an off state while the electrostatic chuck 30 is in operation, and disconnects the ammeter 85 from the DC power supply circuit. When the inspection circuit is used, the on / off switch 88 is turned on and the ammeter 42 is turned on. Is inserted into the DC power feeding circuit.

  An on / off switch 90 is also connected between the susceptor 14 and the ground potential terminal. The on / off switch 90 is also kept in an off state in a steady state, particularly during plasma processing, and is turned on when the inspection circuit is used to ground the susceptor 14. Yes.

  The control unit 54 (FIG. 1) may control all the switches in this inspection circuit, read the measurement value of the ammeter 85, and output the monitoring result through a display or the like.

In this inspection circuit, as shown in FIG. 10, when the changeover switch 40 is switched to the cut-off position, for example, the on / off switch 86 (3) in the third row is selectively turned on, the DC voltage from the DC power source 36 is obtained. Are electrostatic adsorption blocks 64 (3,1), 64 (3,2), 64 (3,3) in the third row via an on / off switch 88, an ammeter 85 and an on / off switch 86 (3). 3) and 64 (3, 4) DC electrodes 34 are applied. When all of the electrostatic adsorption blocks 64 (3,1) to 64 (3,4) in the third row are normal, no current flows in the DC power supply circuit, and the ammeter 85 shows a zero current value. . However, when any of a electrostatic adsorption block 64 in the third row (3,1) to 64 (3, 4) may have been reached insulation failure, especially lower dielectric layer 32A _L are dielectric breakdown When this occurs, a leakage current flows between the DC electrode 34A of the electrostatic adsorption block and the susceptor 14 having the ground potential. That is, current flows through the DC power feeding circuit, and the ammeter 85 indicates the current value of the leakage current. In this case, the control unit 54 (FIG. 1) outputs a monitoring result indicating that any one of the electrostatic adsorption blocks 64 (3,1) to 64 (3,4) in the third row is causing dielectric breakdown. .

  When such a monitoring result is given, for example, a defective block may be manually determined using a tester and the defective block may be replaced.

  The inspection circuit of FIG. 11 can be suitably applied when the electrostatic chuck block 64 is configured as a bipolar type, and automatically sets the electrostatic chuck blocks 64 (1,1) to 64 (4,4) to 1. It has a function to check pass / fail individually.

More specifically, one DC electrode 34A ₁ provided in the DC power source 36 and the electrostatic adsorption blocks 64 (i, 1) to 64 (i, 4) (where i = 1, 2, 3, 4) in each row. ON / OFF switches 86 (1) to 86 (4) are connected in series with the terminals, and the electrostatic chuck blocks 64 (1, j) to 64 (4, j) of the terminals and each row (where j = other DC electrodes 34A ₂ in series with the on / off switch 87 provided on the 1, 2, 3, 4) (1) to 87 (4) is connected. An on / off switch 90 (FIG. 10) for grounding the susceptor 14 during inspection is not provided, but an on / off switch 92 is provided instead.

Each column on / off switch 87 (1) to 87 (4), the steady state, while the particular plasma process is performed maintaining the ON state to keep the DC electrodes 34A ₂ of each column to the ground potential. In this case, instead of the ground potential, it is also possible to apply a DC electrode 34A _2, for example a negative DC voltage in each column. When this inspection circuit is used, one of the on / off switches 87 (1) to 87 (4) is selectively turned on at a time, and the others are kept off. It has become.

In this inspection circuit, as shown in FIG. 11, for example, when inspecting the electrostatic adsorption block 64 (2, 3) in the second row and the third column, the on / off switch 86 (3) in the second row. And the third row on / off switch 87 (3) are selectively turned on. Then, the electrostatic attraction block 64 only in (2,3), connected to the ammeter 85 in series between one of the DC electrodes 34A ₁ and the other DC electrodes 34A ₂ is a DC power supply 36 and a ground potential terminal The Therefore, if dielectric breakdown occurs in the dielectric layer 32A in the electrostatic adsorption block 64 (2,3), a leakage current flows between the DC electrodes 34A ₁ and 34A ₂ , and the ammeter 85 The same current also flows. In this case, the control unit 54 (FIG. 1) outputs a monitoring result indicating that the electrostatic attraction block 64 (2, 3) in the second row and the third column has undergone dielectric breakdown. The same inspection as described above can be performed for all other electrostatic adsorption blocks.

  Further, the same inspection as described above can be performed on the electrostatic chuck block 66 of the peripheral electrostatic chuck 62.

  In the above embodiment, not only the central electrostatic attraction unit 60 but also the peripheral electrostatic attraction unit 62 has a function of adsorbing the substrate G with an electrostatic force. The substrate G can be held horizontally by fully correcting it on the chuck 30. Along with such a decrease in strength, accuracy, and stability of the substrate holding force, as a modification, a configuration in which the peripheral electrostatic attraction portion 62 is replaced with a peripheral support portion only of a ceramic material (32B) without the DC electrode 34B is also possible. It is.

  Furthermore, in the plasma etching apparatus according to the above-described embodiment, since the susceptor 14 also serves as a high-frequency electrode, the high-frequency wave can be satisfactorily transmitted to the peripheral electrostatic attraction portion 62 or the dielectric layer of the peripheral support portion and the plasma resistance can be improved. A high ceramic material can be suitably used. However, the present invention is not limited to the plasma etching apparatus of the above embodiment, but can be applied to other plasma etching apparatuses having different plasma generation methods, and other plasma processing apparatuses having different plasma processes such as plasma CVD. The present invention can be applied to an apparatus, a plasma ashing apparatus, and the like, and further can be applied to a vacuum apparatus that does not use plasma, such as an ion implantation apparatus. Further, depending on the process atmosphere of the chamber, it is possible to use a dielectric material other than ceramics as the dielectric layer of the peripheral electrostatic attraction portion 62 or the peripheral support portion. It is also possible to replace it with metal.

  In the above embodiment, each of the electrostatic adsorption blocks 64 and 66 has the gas holes 72A and 72B through which the heat transfer gas passes, but a configuration in which only some of the blocks have the gas holes 72A and 72B discretely is also possible. is there.

  In addition, the shape, arrangement form / layout, number / size of the electrostatic adsorption blocks 64 and 66 in the above embodiment are merely examples, and arbitrary or plural types of block shapes, any arrangement form / layout, any number / size can be selected. You can choose. Therefore, for example, the electrostatic adsorption block 66 or the peripheral support member can be configured to connect four long sides in a frame shape, or as an integral single frame.

  The substrate to be processed held on the mounting table by the electrostatic chuck of the present invention is not limited to a glass substrate, but may be another insulating substrate such as a plastic substrate, or a silicon substrate or the like.

10 chambers
14 Susceptor (mounting table, lower electrode)
16 High frequency power supply 20 Shower head (upper electrode)
24 Processing gas supply unit 30 Electrostatic chuck 32 Dielectric layer of dielectric layer 32A (central electrostatic adsorption unit) 32B (peripheral electrostatic adsorption unit) dielectric layer 34 DC electrode 34A (central electrostatic adsorption unit) DC DC electrode 36 of electrode 32B (peripheral electrostatic adsorption part) 36 DC (direct current) power supply 50 Exhaust mechanism 52 Control part 60 Central electrostatic adsorption part 62 Peripheral electrostatic adsorption part 64 Electrostatic adsorption block 66 of central electrostatic adsorption part 66 Electrostatic adsorption block of (peripheral electrostatic adsorption part)

Claims (13)

An electrostatic chuck for adsorbing a substrate to be processed by an electrostatic force and holding it on a mounting table in a depressurizable processing container,
A first dielectric layer made of a resin and disposed in an area inside the outer peripheral edge of the substrate on the mounting surface of the mounting table, and a first electrode provided inside the first dielectric layer A first electrostatic attraction part having:
A second dielectric layer made of ceramics and a second dielectric layer disposed around the first electrostatic attraction portion on the mounting surface of the mounting table so as to surround the first electrostatic adsorption portion. A second electrostatic attraction part having two electrodes;
A direct current power source for individually and simultaneously applying independent direct current voltages to the first and second electrodes,
On the mounting surface of the mounting table, an outer peripheral edge of the first electrostatic attraction unit is located on the inner side of the Debye length of plasma generated in the processing container from the outer peripheral edge of the substrate, The outer peripheral edge of the electrostatic chuck is located outside the outer peripheral edge of the substrate,
Electrostatic chuck. The first electrostatic attraction part comprises a plurality of first electrostatic attraction blocks divided in a one-dimensional direction or a two-dimensional direction on the placement surface of the mounting table,
Each of the first electrostatic attraction blocks has the first dielectric layer and the first electrode independent for each block,
The electrostatic chuck according to claim 1.   The m × n (m and n are natural numbers) first electrostatic adsorption blocks are arranged in m rows × n columns, and the m × n number of the first electrostatic adsorption blocks respectively provided in the first electrostatic adsorption blocks. The electrostatic chuck according to claim 2, wherein the electrodes are electrically connected in parallel to the DC power source. In order to detect a dielectric breakdown in the first electrostatic adsorption unit,
a switch circuit for electrically connecting the mxn first electrodes to the DC power supply in units of rows or columns;
The electrostatic chuck according to claim 3, further comprising: an ammeter connected between an output terminal of the DC power supply and the first electrode, or between the first electrode and a reference voltage terminal. The second electrostatic adsorption part is composed of a plurality of second electrostatic adsorption blocks divided in a one-dimensional direction or a two-dimensional direction on the mounting surface of the mounting table.
Each of the second electrostatic adsorption blocks has the second dielectric layer and the second electrode independent for each block.
The electrostatic chuck as described in any one of Claims 1-4.   The electrostatic chuck according to any one of claims 1 to 5, wherein the substrate on the mounting table in the processing container is exposed to plasma to receive a desired plasma processing.   7. The static electricity according to claim 1, wherein an outer peripheral edge of the first electrostatic attraction portion is positioned outside an element formation region of the substrate on the mounting surface of the mounting table. Electric chuck.   The said 1st electrostatic attraction | suction part has a 1st gas hole which lets the heat-transfer gas for thermally couple | bonding the mounting base and the said board | substrate through the said statement, The Claim 1-7. Electrostatic chuck.   The said 2nd electrostatic attraction | suction part has a 2nd gas hole which lets the heat-transfer gas for thermally couple | bonding the mounting base and the said board | substrate to the above-mentioned to the said 1st-8. Electrostatic chuck.   The electrostatic chuck according to claim 1, wherein the ceramic includes aluminum oxide, aluminum nitride, or silicon carbide.   The electrostatic chuck according to claim 1, wherein the resin is polyimide.   The electrostatic chuck according to claim 1, wherein the substrate to be processed is a glass substrate, a plastic substrate, or a silicon substrate. A processing container capable of decompression;
A mounting table for mounting the substrate to be processed in the processing container;
A plasma generating unit for generating plasma of a processing gas in the processing container;
The plasma processing apparatus which has an electrostatic chuck as described in any one of Claims 1-12 for adsorb | sucking the said board | substrate by an electrostatic force and hold | maintaining on the mounting base.

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