Chuck table and processing device

Abstract

To provide a chuck table capable of adjusting the temperature of a holding surface by a structure inside the chuck table.SOLUTION: The chuck table is for suction holding a workpiece when the workpiece is processed. The chuck table includes a holding surface for suction holding a workpiece and a cooling passage for flowing a refrigerant provided inside the chuck table. The cooling passage has a supply port for supplying the refrigerant to the cooling passage and a discharge port for discharging the refrigerant from the cooling passage. Cross-sectional areas of a first area and a second area arranged at positions corresponding to two locations having different holding surfaces between the supply port and the discharge port are different.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a chuck table that suction-holds a workpiece when the workpiece is processed. [Background technology]

[0002] Electronic devices such as mobile phones and PCs (Personal Computers) are equipped with device chips having devices such as electronic circuits. In general, device chips are manufactured by processing workpieces including wafers made of semiconductor materials such as silicon.

[0003] For example, device chips are manufactured by dividing the wafer into multiple regions using multiple planned dividing lines (streets) arranged in a grid pattern on the front side of the wafer, forming devices in each region, and then dividing the wafer along each planned dividing line.

[0004] A cutting blade, a laser beam, etc. are used to divide the wafer. In recent years, in order to make the device chips thinner and lighter, the back surface of the wafer after devices are formed on the front surface is sometimes ground to thin the wafer.

[0005] However, when a wafer is subjected to processing such as cutting, laser processing, grinding, etc., the flexural strength of the device chip after the wafer processing is reduced due to chipping, grinding distortion, etc. Therefore, a technology has been proposed in which the wafer is plasma-etched with plasma gas using a plasma etching device (see, for example, Patent Document 1) to remove chipping, grinding distortion, etc.

[0006] The plasma etching apparatus has a chamber, and a chuck table is provided in the chamber to suck and hold the workpiece. During plasma etching, the workpiece sucked and held on the holding surface of the chuck table is etched by plasma gas containing reactive ions, radicals, etc., to remove chipping, grinding distortion, etc.

[0007] During plasma etching, the chuck table becomes hot, but by cooling the chuck table with cooling water flowing through a flow path within the chuck table, excessive temperature rise of the chuck table is reduced.

[0008] The temperature distribution on the holding surface of the chuck table affects the processing quality of plasma etching, and also affects the processing quality of other processes such as grinding and dry polishing, not limited to plasma etching. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] JP 2016-171291 A Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above problems, and has an object to provide a chuck table in which the temperature distribution on the holding surface can be adjusted by the internal structure of the chuck table. [Means for solving the problem]

[0011] According to one aspect of the present invention, there is provided a chuck table that suction-holds a workpiece when the workpiece is processed, the chuck table comprising a holding surface that suction-holds the workpiece, and a cooling passage for flowing a coolant provided inside the chuck table, the cooling passage having a supply port for supplying the coolant to the cooling passage and an exhaust port for exhausting the coolant from the cooling passage, the chuck table having different cross-sectional areas in a first region and a second region that are respectively arranged at positions corresponding to two different points on the holding surface between the supply port and the exhaust port.

[0012] Preferably, each of the supply port and the discharge port is provided on the other surface of the chuck table located opposite the holding surface in the thickness direction, and the cooling path includes a supply path extending from the supply port along the thickness direction, a discharge path extending from the discharge port along the thickness direction, and a parallel path connecting the supply path and the discharge path, which is provided so as to extend along the holding surface between the supply path and the discharge path when the holding surface is viewed in a plane, and the first region and the second region are provided on the parallel path.

[0013] The parallel path has a third region and a fourth region that are arranged closer to the supply port than the discharge port in the direction in which the parallel path extends and are adjacent to each other in a direction proceeding from the center of the holding surface to the outer periphery of the holding surface, and a fifth region and a sixth region that are arranged closer to the discharge port than the supply port in the direction in which the parallel path extends and are adjacent to each other in a direction proceeding from the center of the holding surface to the outer periphery, and the distance between the fifth region and the sixth region is smaller than the distance between the third region and the fourth region.

[0014] According to another aspect of the present invention, there is provided a processing apparatus having the above-mentioned chuck table, comprising a processing unit for processing the workpiece held by suction on the chuck table, and a temperature control unit including a heat exchanger for adjusting the temperature of the coolant, wherein the coolant discharged from the outlet has its temperature adjusted by the temperature control unit and is then supplied to the cooling path from the supply inlet.

[0015] Preferably, the processing unit is a plasma processing unit having a chamber in which the chuck table is disposed, and a high frequency power source for generating plasma from a raw material gas. Effect of the Invention

[0016] In a chuck table according to one aspect of the present invention, the cross-sectional areas of the first and second regions, which are disposed at positions corresponding to two different points on the holding surface between the supply port and the discharge port, are different. In other words, the flow rate of the cooling path can be changed in each of the first and second regions. In other words, the temperature distribution on the holding surface can be adjusted due to the internal structure of the chuck table. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a partial cross-sectional side view of the plasma etching apparatus. [Diagram 2] FIG. 2 is an enlarged view of the interior of the chamber. [Diagram 3] FIG. [Figure 4] FIG. 4(A) is a top view of the support plate, and FIG. 4(B) is a bottom view of the support plate. [Diagram 5] FIG. 5(A) shows the flow velocity distribution when the support plate of this embodiment is used, and FIG. 5(B) shows the flow velocity distribution when the support plate of the comparative example is used. [Figure 6] FIG. 6(A) shows the temperature distribution on the holding surface when the support plate of this embodiment is used, and FIG. 6(B) shows the temperature distribution on the holding surface when the support plate of the comparative example is used. [Figure 7] FIG. 4 is a bottom view of the support plate according to the first embodiment. [Figure 8] FIG. 11 is a bottom view of a support plate according to a modified example of the first embodiment. [Figure 9] FIG. 11 is a bottom view of a support plate according to the second embodiment. [Figure 10] FIG. 11 is a bottom view of a support plate according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] (First embodiment) An embodiment according to one aspect of the present invention will be described with reference to the accompanying drawings. Fig. 1 is a partially cross-sectional side view of a plasma etching apparatus (processing apparatus) 2 equipped with a chuck table 4 according to a positional aspect of the present invention. In Fig. 1, a part of the plasma etching apparatus 2 is shown in functional blocks.

[0019] The plasma etching apparatus 2 includes a rectangular parallelepiped chamber 6. The chamber 6 has a bottom wall, a top wall, and four side walls. The interior of the chamber 6 corresponds to a processing space where plasma processing is performed. An opening 8 is provided in one of the side walls.

[0020] The opening 8 functions as an entrance / exit for the workpiece 11 to / from the chamber 6. A vacuum gate valve 10 having an electrically or pneumatically driven valve body is provided on the outside of the opening 8. The opening 8 is opened and closed by the movement of the valve body.

[0021] An exhaust path 12 is provided in the bottom wall of the chamber 6. An exhaust mechanism 14 including a vacuum pump and the like for exhausting the processing space in the chamber 6 is connected to the exhaust path 12. Inside the chamber 6, the above-mentioned chuck table 4 is disposed.

[0022] 2 is an enlarged view of the inside of the chamber 6. The chuck table 4 has a disk-shaped holding plate 16. The holding plate 16 is made of a ceramic material such as aluminum oxide or aluminum nitride. The diameter of the holding plate 16 is, for example, 314 mm.

[0023] The holding plate 16 has a circular holding surface 16a. A suction path 16b is formed inside the holding plate 16, one end of which is connected to a suction source 18 such as a vacuum pump. The other end of the suction path 16b is exposed to the holding surface 16a, and negative pressure generated by the suction source 18 is transmitted to the holding surface 16a via the suction path 16b.

[0024] A sheet-like or mesh-like conductor (not shown) is embedded inside the holding plate 16. When a DC voltage is applied to the conductor from a DC power source (not shown), the workpiece 11 is attracted and held by the holding surface 16a due to an electric force such as electrostatic attraction.

[0025] The workpiece 11 is attracted and held on the holding surface 16a by the negative pressure transmitted to the holding surface 16a and / or the electrostatic force from the conductor. Usually, when the pressure in the processing space is atmospheric pressure, the negative pressure is used, and when the pressure in the processing space is vacuum (e.g., 100 kPa or less), the electrostatic force is used.

[0026] The holding plate 16 is supported by a disk-shaped supporting plate 20. The supporting plate 20 has a larger diameter than the holding plate 16 (for example, the diameter of the supporting plate 20 is 370 mm). The supporting plate 20 is formed of a conductive metal such as aluminum, and has a circular upper surface 20a and a lower surface (other surface) 20b.

[0027] A lower surface 20b of the support plate 20 is located on the opposite side to the holding surface 16a in the thickness direction 4a of the chuck table 4. The support plate 20 is disposed concentrically with the holding plate 16 such that an upper surface 20a of the support plate 20 contacts the lower surface of the holding plate 16.

[0028] A high-frequency power source 22 for guiding the plasmatized raw material gas 54a to the workpiece 11 is electrically connected to the support plate 20 via a matching unit (high-frequency matching device) (not shown) or the like.

[0029] The high frequency power supply 22 applies, for example, an AC voltage of 13.56 MHz and 300 V to the support plate 20. The support plate 20 has a function of cooling the holding plate 16 in addition to the function of the lower electrode.

[0030] A cooling path 24 for flowing a coolant 24a is provided inside the support plate 20. The cooling path 24 has a supply port 24b and a discharge port 24c, both of which are provided on the lower surface 20b of the support plate 20. The coolant 24a is supplied to the cooling path 24 via the supply port 24b and discharged from the cooling path 24 via the discharge port 24c.

[0031] The coolant 24a may be, for example, (i) pure water, (ii) ethylene glycol, or (iii) a chemically inactive and electrically insulating fluorine-based coolant. Examples of the fluorine-based coolant include perfluoropolyether (PFPE), perfluorocarbon (PFC), and hydrofluoroether (HFE).

[0032] In this embodiment, Galden (registered trademark) (e.g., Galden HT135) sold by Solvay Specialty Polymers Japan KK is used, but the refrigerant is not limited to this, and other refrigerants such as Fluorinert sold by 3M Japan KK can also be used.

[0033] The holding plate 16 and the support plate 20 are fixed together by a fixing ring 26. That is, the chuck table 4 of the present embodiment includes the holding plate 16, the support plate 20, and the fixing ring 26. The chuck table 4 is supported by a cylindrical support portion 28.

[0034] The support part 28 is disposed concentrically with the chuck table 4. As shown in FIG. 1 , the support part 28 is disposed so as to pass through an opening 32 provided in the bottom wall of the chamber 6 via an annular insulating member 30, and is fixed to the chamber 6.

[0035] An electrical path (not shown) is provided inside the support portion 28 for electrically connecting the conductor inside the holding plate 16 to a DC power source, and an electrical path is provided for electrically connecting the support plate 20 to the high-frequency power source 22.

[0036] 2, a circulation path 28a connected to the cooling path 24 of the support plate 20 and a suction path 28b connected to the suction path 16b of the holding plate 16 are formed inside the support part 28. The circulation path 28a of the support part 28 is connected to a refrigerant circulation mechanism 34.

[0037] The coolant circulation mechanism 34 includes a pump 36 for pumping the coolant 24a. The coolant circulation mechanism 34 further includes a temperature adjustment unit 38 including a heat exchanger 40 for adjusting the temperature of the coolant 24a. The heat exchanger 40 in this embodiment is of an air-cooling type or a liquid-cooling type, and cools the coolant 24a heated by the chuck table 4 to a predetermined temperature.

[0038] The refrigerant 24a discharged from the exhaust port 24c of the support plate 20 to the circulation path 28a of the support part 28 is cooled to a predetermined temperature by the temperature control unit 38 (i.e., after the temperature is adjusted), and then supplied to the cooling path 24 of the support plate 20 from the supply port 24b of the support plate 20.

[0039] Here, the cooling passage 24 of the support plate 20 will be described with reference to Fig. 3, Fig. 4(A) and Fig. 4(B). Fig. 3 is an enlarged perspective view of the chuck table 4. For convenience of explanation, the fixing ring 26 is omitted in Fig. 3.

[0040] 3, the supply port 24b of the cooling path 24 is disposed in the radial center of the support plate 20, and the cooling path 24 includes a supply path 24d extending from the supply port 24b along the thickness direction 4a of the chuck table 4. The supply path 24d is formed along the thickness direction 4a from the lower surface 20b of the support plate 20 to a predetermined position not reaching the upper surface 20a.

[0041] Further, the discharge port 24c of the cooling path 24 is disposed on the outer periphery of the support plate 20, and the cooling path 24 includes a discharge path 24e extending from the discharge port 24c along the thickness direction 4a of the chuck table 4. The discharge path 24e is formed along the thickness direction 4a from a predetermined position not reaching the upper surface 20a of the support plate 20 to the lower surface 20b.

[0042] Furthermore, the cooling path 24 includes a parallel path 24f that connects the supply path 24d and the discharge path 24e. The parallel path 24f is provided so as to extend along the upper surface 20a of the support plate 20 when the upper surface 20a of the support plate 20 is viewed in a plan view (i.e., along the holding surface 16a when the holding surface 16a is viewed in a plan view).

[0043] In addition, the parallel paths 24f do not necessarily mean that they are arranged parallel to each other. The parallel paths 24f in this embodiment mean that the distance from the holding surface 16a is approximately constant and the parallel paths 24f are arranged approximately parallel to the holding surface 16a.

[0044] In particular, the parallel paths 24f of the cooling paths 24 are arranged in a spiral shape when the upper surface 20a is viewed in plan (i.e., when the holding surface 16a is viewed in plan). Therefore, the coolant 24a flows from the center to the outer periphery in the radial direction of the support plate 20 while swirling inside the support plate 20.

[0045] The supply path 24d, the discharge path 24e, and the parallel path 24f are each a cylindrical flow path. In this embodiment, the diameter of the supply path 24d is a first value (e.g., 14 mm), and the diameter of the discharge path 24e is a second value (e.g., 12 mm) smaller than the first value.

[0046] From one end of the parallel passage 24f (i.e., the upper end of the supply passage 24d) to the other end of the parallel passage 24f (i.e., the upper end of the discharge passage 24e), the diameter of the flow path gradually narrows as it progresses from the supply passage 24d to the discharge passage 24e (see Figures 4(A) and 4(B)).

[0047] The length from the upper end of the supply path 24d to the upper end of the discharge path 24e is, for example, about 1000 mm, and the diameter of the flow path linearly narrows as it moves from the upper end of the supply path 24d to the upper end of the discharge path 24e.

[0048] In other words, when the upper end of the supply path 24d is taken as the origin, the diameter D(X) of the flow path relative to the distance X from the origin in the direction in which the parallel path 24f extends satisfies the relationship D(X) = A·X + B (A and B are positive real numbers).

[0049] Next, with reference to FIGS. 4(A) and 4(B), the relationship between the diameter of the parallel channel 24f and the flow velocity of the refrigerant 24a will be further described. FIG. 4(A) is a top view of the support plate 20, and FIG. 4(B) is a bottom view of the support plate 20.

[0050] The parallel channel 24f of the cooling channel 24 includes a central region (first region) 24f1 disposed closer to the supply port 24b than to the discharge port 24c, and an outer peripheral region (second region) 24f2 disposed closer to the discharge port 24c than to the supply port 24b.

[0051] The diameter D2 (not shown) of the flow channel in the outer peripheral region 24f2 of the parallel channel 24f is smaller than the diameter D1 (not shown) of the flow channel in the central region 24f1 of the parallel channel 24f. The diameter D1 and the diameter D2 of the present embodiment satisfy (12 mm ≦ D2 < D1 ≦ 14 mm).

[0052] Therefore, the cross-sectional area S2 of the flow channel in the outer peripheral region 24f2 of the parallel channel 24f is smaller than the cross-sectional area S1 of the flow channel in the central region 24f1 of the parallel channel 24f (that is, cross-sectional area S2 < cross-sectional area S1). That is, the cross-sectional areas of the central region 24f1 and the outer peripheral region 24f2 respectively disposed at positions corresponding to two different locations on the holding surface 16a are different.

[0053] During plasma etching, generally, the processed region is heated by heat, and the higher the temperature of the processed region, the higher the etching rate. Therefore, when the temperature of a specific region becomes high, variations in the removal amount of the workpiece 11 by plasma etching occur, and the temperature distribution becomes non-uniform within the holding surface 16a. In order to reduce the variations in the removal amount by reducing this non-uniform temperature distribution, the refrigerant 24a is used.

[0054] In the present embodiment where the refrigerant 24a is supplied from the central portion of the holding surface 16a and discharged from the outer peripheral portion of the holding surface 16a, the temperature of the refrigerant 24a passing through the outer peripheral portion of the holding surface 16a tends to be higher than the temperature of the refrigerant 24a passing through the central portion of the holding surface 16a.

[0055] In this embodiment, in order to reduce the non-uniformity of the temperature distribution on the holding surface 16a, the flow rate of the coolant 24a is controlled based on the cross-sectional area of ​​the parallel passage 24f (i.e., by the internal structure of the chuck table 4). The cross-sectional area of ​​the parallel passage 24f means the pipe diameter used to define the flow rate. Here, the relationship between the flow rate and the heat transfer coefficient h will be described.

[0056] Generally, the diameter of a cylinder is d (unit: m), and the dynamic viscosity of the fluid flowing inside the cylinder is ν (unit: m 2 / s), the average flow velocity U (unit: m / s) of the fluid and the Reynolds number Re satisfy the following formula (1). In other words, the Reynolds number Re increases in proportion to the average flow velocity U of the fluid.

[0057] Re = (U d) / ν…(1)

[0058] Generally, when a fluid flowing inside a cylinder is turbulent, the Nusselt number Nu, which is an index of heat transfer capacity, is expressed by the following formula (2) using the Prandtl number Pr, which is a value specific to the fluid. In other words, when the Reynolds number Re increases in proportion to the average flow velocity U of the fluid, the Nusselt number Nu also increases.

[0059] Nu = 0.023 (Re) 4 / 5 (Pr) 1 / 3 …(2)

[0060] Furthermore, the heat transfer coefficient h (unit: W / (m 2 The heat transfer coefficient (h) is expressed by the following formula (3) using the thermal conductivity of the fluid λ (unit: W / (m K)) and the diameter d of the cylinder mentioned above. In other words, when the Reynolds number Re increases in proportion to the average flow velocity U of the fluid, the Nusselt number Nu increases, and as a result, the heat transfer coefficient h also increases.

[0061] h = (Nu λ) / d…(3)

[0062] In this manner, by increasing the flow velocity of the refrigerant 24a, the heat transfer coefficient h is improved. Therefore, in this embodiment, the cross-sectional area S2 of the parallel paths 24f in the outer circumferential region 24f2 is made smaller than the cross-sectional area S1 of the parallel paths 24f in the central region 24f1, so that the flow velocity of the refrigerant 24a in the outer circumferential region 24f2 (i.e., downstream of the parallel paths 24f) is made higher than the flow velocity of the refrigerant 24a in the central region 24f1 (i.e., upstream of the parallel paths 24f).

[0063] This improves the heat transfer coefficient h at the outer periphery of the holding surface 16a. When the fluid flowing inside the cylinder is a laminar flow, heat exchange does not proceed as easily as when the fluid flowing inside the cylinder is a turbulent flow, but even in the case of a laminar flow, the higher the average flow velocity U of the fluid is, the higher the heat transfer coefficient h becomes.

[0064] In this embodiment, the temperature difference between the center temperature of the holding surface 16a and the temperature of the outer periphery of the holding surface 16a is reduced when the chuck table 4 is heated by an external heat source such as plasma gas, compared to a case in which the cross-sectional area of ​​the cooling path 24 is constant between the supply port 24b and the discharge port 24c of the cooling path 24 and the interval between adjacent cooling paths 24 is constant between the supply port 24b and the discharge port 24c when the holding surface 16a is viewed in plan. Therefore, it is possible to reduce non-uniformity in the temperature distribution on the holding surface 16a.

[0065] Next, the results of analyzing the effect of reducing non-uniformity in temperature distribution by fluid simulation will be described with reference to FIGS. 5(A), 5(B), 6(A) and 6(B).

[0066] For the fluid simulation, SOLIDWORKS Flow Simulation, a software of SOLIDWORKS (registered trademark) sold by Dassault Systemes SolidWorks Corporation, was used.

[0067] FIG. 5(A) shows a simulation result showing the distribution of flow velocity of the refrigerant 24a in the cooling passage 24 when the support plate 20 of this embodiment is used, and FIG. 5(B) shows a simulation result showing the distribution of flow velocity of the refrigerant 24a in the cooling passage 24 when the support plate 20 of the comparative example is used.

[0068] In the support plate 20 of this embodiment (Figure 5(A)), the diameter of the supply port 24b and the supply path 24d is 14 mm, the diameter of the discharge port 24c and the discharge path 24e is 12 mm, and the diameter of the parallel path 24f linearly narrows as it proceeds from the upper end of the supply path 24d to the upper end of the discharge path 24e along the direction in which the parallel path 24f extends.

[0069] In contrast, in the support plate 20 of the comparative example (FIG. 5(B)), the diameters of the supply port 24b and the discharge port 24c are 10 mm, and the diameters of the supply path 24d, the discharge path 24e and the parallel path 24f are also constant at 10 mm.

[0070] 5(A) and 5(B), the positions of the supply port 24b and the discharge port 24c are indicated by arrows when the support plate 20 is viewed from above. The flow velocity (m / s) of the coolant 24a is represented by color. However, due to the grayscale display, the flow velocity is represented by light and dark shades.

[0071] 5(B) was used, the flow rate of the refrigerant 24a was 10 L / min, the Reynolds number Re was 8842 (i.e., turbulent flow), the Prandtl number Pr was 64, the Nusselt number Nu was 132, and the length of the parallel path 24f was 1000 mm. The temperature of the object to be cooled was 50°C.

[0072] In contrast, in the simulation shown in Fig. 5(A), the conditions other than the diameter of the parallel path 24f were the same as those in the simulation shown in Fig. 5(B). However, by changing the diameter of the parallel path 24f, the Reynolds number Re, the Nusselt number Nu, the heat transfer coefficient h, etc. change depending on the position of the parallel path 24f.

[0073] In the experimental example shown in Figure 5 (A), the flow velocity of the parallel path 24f located on the outermost periphery of the left half is approximately 2200 m / s to approximately 2400 m / s, which is higher than the flow velocity (approximately 1700 m / s to approximately 1900 m / s) of the parallel path 24f adjacent to the innermost parallel path 24f on the left half.

[0074] The flow velocity (about 2200 m / s to about 2400 m / s) of the parallel path 24f located on the outermost periphery of the left half shown in Fig. 5(A) is higher than the flow velocity (about 1700 m / s to about 1800 m / s) of the parallel path 24f located on the outer periphery of the left half in Fig. 5(B). In addition, in Fig. 5(B), the flow velocity of the parallel path 24f on the outermost periphery of the left half is approximately the same as the flow velocity of the parallel path 24f adjacent to the inner side of the outermost periphery of the left half.

[0075] FIG. 6(A) is a simulation result showing the temperature distribution on the holding surface 16a when the support plate 20 of this embodiment is used, similar to FIG. 5(A), and FIG. 6(B) is a simulation result showing the temperature distribution on the holding surface 16a when the support plate 20 of the comparative example is used, similar to FIG. 5(B).

[0076] In Figures 6(A) and 6(B), the temperature (K) of the holding surface 16a is expressed by color. However, for grayscale display, the temperature is displayed in shades of gray. K is the SI unit of thermodynamic temperature, i.e., kelvin.

[0077] In FIG. 6(A), the temperature of the holding surface 16a is approximately constant over a relatively wide range, with the exception that the temperature in the arc-shaped region from 9 o'clock to 12 o'clock on the outer periphery of the holding surface 16a is approximately 2 K to 4 K higher than the temperature in the center of the holding surface 16a.

[0078] 6B, the temperature of the left half of the holding surface 16a is higher than the temperature of the right half of the holding surface 16a, and the temperature of the outermost region (i.e., the C-shaped region) in the left half of the holding surface 16a is particularly high. The temperature of the peak region 24g is about 10 K higher than the temperature of the center of the holding surface 16a.

[0079] The difference in temperature distribution between Figures 6(A) and 6(B) is thought to reflect the difference in flow speed in the parallel path 24f located at the outermost periphery in the left half of Figure 6(A), and it can be seen that the non-uniformity of the temperature distribution has been reduced in Figure 6(A).

[0080] In this way, compared to the support plate 20 of the comparative example in which the cross-sectional area of ​​the cooling path 24 is constant between the supply port 24b and the discharge port 24c and the spacing between adjacent cooling paths 24 is constant between the supply port 24b and the discharge port 24c when the holding surface 16a is viewed in a plane, in the support plate 20 of the present embodiment, when the chuck table 4 is heated by an external heat source such as plasma gas, the temperature difference between the temperature at the center of the holding surface 16a and the temperature at the outer periphery of the holding surface 16a is reduced.

[0081] In other words, by adopting the structure of the cooling paths 24 in the support plate 20 of this embodiment, it is possible to improve the uniformity of the temperature distribution on the holding surface 16a. Here, other components of the plasma etching apparatus 2 will be described with reference to Figures 1 and 2 again.

[0082] 2, a disk-shaped head unit 42 is provided above the chuck table 4 so as to face the holding surface 16a. The head unit 42 functions as an electrode to which a voltage for generating plasma is applied, and as a gas supply unit for supplying an etching gas to the processing space.

[0083] The head portion 42 includes a support plate 44 made of a conductive metal, and a gas supply plate 46 made of a conductive metal, semiconductor, etc. The support plate 44 and the gas supply plate 46 are fixed together by an annular fixing ring 48.

[0084] A cooling passage 44a is formed inside the support plate 44. Furthermore, a plurality of gas supply passages 46b are formed inside the gas supply plate 46, the gas supply passages 46b opening at a lower surface 46a of the gas supply plate 46. The support plate 44 is supported by a cylindrical support portion 50.

[0085] Inside the support portion 50, a circulation path 50a connected to the cooling path 44a of the support plate 44, and gas supply paths 50b connected to the multiple gas supply paths 46b of the gas supply plate 46 are formed.

[0086] The circulation path 50a of the support part 50 is connected to a coolant circulation mechanism 52. During plasma etching, the head part 42 is heated by heat caused by the plasma, but by cooling the support plate 44 via a coolant 52a supplied from the coolant circulation mechanism 52, an excessive temperature rise of the head part 42 is suppressed.

[0087] The refrigerant circulation mechanism 52 is substantially the same as the above-mentioned refrigerant circulation mechanism 34, and therefore a duplicated description will be omitted. The refrigerant circulation mechanisms 34, 52 may each have one temperature adjustment unit 38, or may share one temperature adjustment unit 38.

[0088] One end of the gas supply path 50b of the support part 50 is connected to the multiple gas supply paths 46b in the gas supply plate 46, and the other end of the gas supply path 50b is connected to a gas supply source 54. The gas supply source 54 has a gas tank containing a source gas 54a used for plasma etching. The source gas 54a contains a fluorine-based gas such as CF4 or SF6.

[0089] The gas supply source 54 further includes a valve, a mass flow controller (MFC), etc., which are provided between the gas tank of the gas supply source 54 and the gas supply path 50b of the support part 50. An electrical path is provided inside the support part 50 to electrically connect the support plate 44 and the gas supply plate 46 to the high frequency power source 56.

[0090] The high frequency power supply 56 is electrically connected to the support plate 44 and the gas supply plate 46 via a matching unit (not shown) or the like. The high frequency power supply 56 applies, for example, an AC voltage of a frequency of 10 kHz and a voltage of 10 kV to the support plate 44 and the gas supply plate 46. The support plate 44 and the gas supply plate 46 function as electrodes for generating plasma from the source gas 54a.

[0091] 1, the support part 50 is disposed so as to pass through an opening 60 provided in the top wall of the chamber 6 via an annular insulating member 58. The upper end part of the support part 50 is connected to the tip part of a support arm 62 provided outside the chamber 6.

[0092] The base end of the support arm 62 is connected to a lifting mechanism 64. The lifting mechanism 64 is fixed to the top wall of the chamber 6, and adjusts the distance between the head portion 42 and the holding surface 16a of the chuck table 4 by raising and lowering the support arm 62.

[0093] The plasma etching apparatus 2 has a controller 66 that controls the vacuum gate valve 10, exhaust mechanism 14, suction source 18, high frequency power supply 22, coolant circulation mechanisms 34, 52, gas supply source 54, high frequency power supply 56, lifting mechanism 64, and the like.

[0094] The controller 66 is configured by a computer having a processor (processing device) represented by a CPU (Central Processing Unit) and a memory (storage device), for example. The memory includes a main storage device such as a DRAM (Dynamic Random Access Memory) and an auxiliary storage device such as a flash memory, a hard disk drive, or a solid state drive.

[0095] The auxiliary storage device stores software including a predetermined program. The functions of the controller 66 are realized by operating the processor and the like in accordance with this software.

[0096] Here, the workpiece 11 will be described. The workpiece 11 has a disk-shaped wafer that is a single crystal substrate made of a semiconductor material such as silicon. On the surface of the workpiece 11, a plurality of streets (planned division lines) are arranged in a lattice pattern.

[0097] A device such as an IC (Integrated Circuit) is formed in each of a plurality of rectangular regions partitioned by a plurality of streets. A plurality of device chips are manufactured by dividing the workpiece 11 into device units along the streets.

[0098] However, there are no limitations on the material, shape, structure, size, etc. of the workpiece 11. The workpiece 11 may have a single crystal substrate formed of a compound semiconductor other than silicon. There are also no limitations on the type, number, shape, structure, size, arrangement, etc. of devices, and the workpiece 11 does not necessarily have to have any devices formed thereon.

[0099] When performing plasma etching on the workpiece 11 using the plasma etching apparatus 2 shown in FIG. 1, the workpiece 11 is suction-held by the holding surface 16a, and the inside of the sealed chamber 6 is evacuated to bring the processing space into a reduced pressure state (e.g., 50 Pa or more and 300 Pa or less).

[0100] In a reduced pressure state, it is difficult to suck and hold the workpiece 11 using the negative pressure transmitted from the suction source 18, so a DC voltage is applied to the conductor provided inside the holding plate 16, and the workpiece 11 is sucked and held by the holding surface 16a using electrostatic force.

[0101] Thereafter, the exhaust mechanism 14 and the refrigerant circulation mechanisms 34, 52 are operated, and raw material gas 54a is supplied from the gas supply source 54 to the head portion 42, while the high-frequency power supply 56 supplies a predetermined high-frequency voltage to the support plate 44 and the gas supply plate 46, and the high-frequency power supply 22 supplies a predetermined high-frequency voltage to the support plate 20 of the chuck table 4.

[0102] The raw material gas 54a supplied to the processing space through the gas supply paths 50b and 46b is converted into plasma gas by a predetermined high frequency voltage supplied by the high frequency power source 56. The workpiece 11 is plasma etched (i.e., processed) by the plasma gas.

[0103] That is, the chuck table 4, the chamber 6, the high frequency power sources 22, 56, the head portion 42, the gas supply source 54, etc. constitute a plasma processing unit (that is, a processing unit) that performs plasma processing on the workpiece 11.

[0104] During plasma etching, the chuck table 4 is heated along with the workpiece 11. However, in the support plate 20 of this embodiment, as described above, the temperature difference between the center of the holding surface 16a and the outer periphery of the holding surface 16a can be reduced.

[0105] FIG. 7 is a bottom view of the support plate 20 according to the first embodiment (i.e., the same as FIG. 4(B)), and in particular, is a view clearly showing multiple adjacent regions in the parallel path 24f in the radial direction 20c of the support plate 20 (i.e., the direction proceeding from the center to the outer periphery of the retaining surface 16a).

[0106] The parallel paths 24f have a third region 24f3 and a fourth region 24f4 adjacent to each other in the radial direction 20c of the support plate 20. The third region 24f3 and the fourth region 24f4 are disposed at positions closer to the supply port 24b than the discharge port 24c in the direction in which the parallel paths 24f extend.

[0107] The parallel paths 24f further include a fifth region 24f5 and a sixth region 24f6 adjacent to each other in the radial direction 20c of the support plate 20. Compared to the third region 24f3 and the fourth region 24f4, the fifth region 24f5 and the sixth region 24f6 are disposed closer to the discharge port 24c than the supply port 24b in the extending direction of the parallel paths 24f.

[0108] (Modification) Fig. 8 is a bottom view of the support plate 20 according to a modification of the first embodiment. In this modification, the interval between the parallel paths 24f in the radial direction 20c is different from the example shown in Fig. 7. The interval 24h2 between the fifth region 24f5 and the sixth region 24f6 is set smaller than the interval 24h1 between the third region 24f3 and the fourth region 24f4 (i.e., the interval 24h2<the interval 24h1).

[0109] In this modified example, the intervals between the parallel paths 24f become smaller in stages as they move outward in the radial direction 20c. This configuration can further reduce the temperature difference between the outer periphery of the holding surface 16a and the center of the holding surface 16a, compared to the example shown in FIG.

[0110] Second Embodiment Next, a second embodiment will be described with reference to Fig. 9. Fig. 9 is a bottom view of the support plate 20 according to the second embodiment. In the second embodiment, the supply port 24b of the cooling path 24 is disposed on the outer periphery of the support plate 20, and the discharge port 24c of the cooling path 24 is disposed in the radial center of the support plate 20. This is different from the first embodiment.

[0111] As shown in FIG. 9, the parallel paths 24f of the cooling paths 24 are arranged in the outer peripheral region (first region) 24f. 1´ and central region (second region) 24f 2´ The outer peripheral region 24f includes 1´ is disposed on the outer periphery of the support plate 20 (i.e., at a position closer to the supply port 24b than the discharge port 24c), and the central region 24f 2´ is disposed at the center in the radial direction of the support plate 20 (that is, at a position closer to the discharge port 24c than the supply port 24b).

[0112] Central region 24f of parallel path 24f 2´ Diameter of flow passage D at 2´ (not shown) is the outer peripheral region 24f of the parallel path 24f 1´ Diameter of flow passage D at 1´ (not shown) is smaller than the central region 24f. 2´ The cross-sectional area S of the flow passage 2´ is the outer periphery area 24f 1´ The cross-sectional area S of the flow passage 1´ (i.e., cross-sectional area S 2´ <Cross-sectional area S 1´ ).

[0113] That is, the outer peripheral regions 24f are disposed at positions corresponding to two different positions on the holding surface 16a. 1´ and central region 24f 2´ The cross-sectional areas are different.

[0114] Outer area 24f 1´ and central region 24f 2´ Reflecting the different cross-sectional areas of the central region 24f near the outlet 24c, 2´ The flow velocity of the coolant 24a in the outer peripheral region 24f close to the supply port 24b is 1´ The flow velocity of the refrigerant 24a is faster than that of the refrigerant 24b at the

[0115] The parallel paths 24f are adjacent third regions 24f in the radial direction 20c of the support plate 20. 3´ and the fourth region 24f 4´ The third region 24f 3´ and the fourth region 24f 4´ is disposed at a position closer to the supply port 24b than the discharge port 24c in the direction in which the parallel path 24f extends.

[0116] The parallel paths 24f are further divided into fifth regions 24f adjacent to each other in the radial direction 20c of the support plate 20. 5´ and the sixth region 24f 6´ The fifth region 24f 5´ and the sixth region 24f 6´ is the third region 24f 3´ and the fourth region 24f 4´ In comparison, it is disposed at a position closer to the discharge port 24c than to the supply port 24b in the direction in which the parallel path 24f extends.

[0117] In this embodiment, in which the refrigerant 24a is supplied from the outer periphery of the holding surface 16a and discharged from the center of the holding surface 16a, the temperature of the refrigerant 24a passing through the center of the holding surface 16a may be higher than the temperature of the refrigerant 24a passing through the outer periphery of the holding surface 16a.

[0118] Therefore, by making the cross-sectional area of ​​the parallel paths 24f in the center of the holding surface 16a smaller than the cross-sectional area of ​​the parallel paths 24f in the outer periphery of the holding surface 16a, the flow rate is increased, and as a result, the heat transfer coefficient h is improved. In other words, the internal structure of the chuck table 4 can improve the uniformity of the temperature distribution on the holding surface 16a.

[0119] 10 is a bottom view of the support plate 20 according to a modification of the second embodiment. In this modification, the interval between the parallel paths 24f in the radial direction 20c of the support plate 20 is different from that in the example shown in FIG. 5´ and the sixth region 24f 6´ Interval 24h 2´ is the third region 24f 3´ and the fourth region 24f 4´ Interval 24h 1´ (i.e., the interval is set to 24 h 2´ <Interval 24h 1´ ).

[0120] In the modified example of the second embodiment, the intervals between the parallel paths 24f become gradually smaller toward the inside in the radial direction 20c, unlike the example shown in Fig. 9. With this configuration, the temperature difference between the outer periphery of the holding surface 16a and the center of the holding surface 16a can be further reduced compared to the example shown in Fig. 9.

[0121] In addition, the structures, methods, etc. according to the above-described embodiments can be appropriately modified without departing from the scope of the present invention. The cross section of the cooling passage 24 is not limited to a circle, and may be a quadrangle such as a rectangle, a square, a rhombus, or a parallelogram.

[0122] In addition, the cross-sectional area of ​​the cooling path 24 is not limited to the example in which the cross-sectional area continuously decreases from the supply port 24b to the discharge port 24c. Furthermore, the structure of the cooling path 24 is not limited to the case in which the temperature of the holding surface 16a is made substantially uniform in the processing process.

[0123] Depending on the expected temperature distribution on the holding surface 16a resulting from the machining process, one or both of the cross-sectional area of ​​the cooling passages 24 and the spacing between the cooling passages 24 may be appropriately adjusted depending on the position within the holding surface 16a.

[0124] Depending on the requirements of the processing process, the temperature of the center of the holding surface 16a may be lower than the temperature of the outer periphery of the holding surface 16a, or the temperature of the outer periphery of the holding surface 16a may be lower than the temperature of the center of the holding surface 16a.

[0125] The above-mentioned plasma etching apparatus 2 is a plasma apparatus that generates so-called dual-frequency excited capacitively coupled plasma (CCP), but the chuck table 4 having the above-mentioned support plate 20 can also be applied to a plasma apparatus that generates capacitively coupled plasma by applying a high-frequency voltage to one of a pair of parallel plate electrodes.

[0126] In addition, the chuck table 4 having the above-mentioned support plate 20 can also be applied to a plasma device that generates electron cyclotron resonance plasma (ECP), helicon wave excited plasma (HWP), inductively coupled plasma (ICP), and microwave excited surface wave plasma (SWP).

[0127] The plasma device (i.e., processing device) can include not only a plasma etching device but also a plasma CVD (Chemical Vapor Deposition) device.

[0128] Furthermore, the chuck table 4 having the above-mentioned holding plate 16 and support plate 20 can also be applied to other processing devices such as a grinding device (i.e., a processing device) that performs grinding, and a polishing device (i.e., a processing device) that performs dry polishing.

[0129] The grinding device includes a grinding unit (i.e., a processing unit) disposed above the chuck table. The grinding unit has a cylindrical spindle. An annular grinding wheel is attached to the lower end of the spindle. The grinding wheel includes an annular base and a plurality of grinding stones disposed at approximately equal intervals on the bottom side of the base.

[0130] The polishing apparatus includes a polishing unit (i.e., a processing unit) disposed above a chuck table. The polishing unit has a cylindrical spindle. A disk-shaped polishing wheel is attached to the lower end of the spindle. The polishing wheel includes a disk-shaped base and one or more polishing pads fixed to the bottom side of the base. [Explanation of symbols]

[0131] 2: Plasma etching equipment (processing equipment) 4: chuck table, 4a: thickness direction 6: chamber, 8: opening, 10: vacuum gate valve 11: Workpiece 12: exhaust passage, 14: exhaust mechanism 16: Holding plate, 16a: Holding surface, 16b: Suction path 18:Suction source 20: Support plate, 20a: Top surface, 20b: Bottom surface (other surface), 20c: Radial direction 22:High frequency power supply 24: Cooling path, 24a: Refrigerant 24b: Supply port, 24c: Discharge port, 24d: Supply path, 24e: Discharge path, 24f: Parallel path 24f1: Center area (first area), 24f2: Outer area (second area) 24f 1´ :Outer area (first area), 24f 2´ :Central area (second area) 24f3,24f 3´ :3rd area, 24f4,24f 4´ :4th area 24f5,24f 5´ :5th area, 24f6,24f 6´ :6th area 24g: Peak area 24h1,24h 1´ ,24h2,24h 2´ :interval 26: Fixing ring 28: Support part, 28a: Circulation path, 28b: Suction path 30: insulating member, 32: opening 34: refrigerant circulation mechanism, 36: pump, 38: temperature control unit, 40: heat exchanger 42: head portion, 44: support plate, 44a: cooling passage 46: gas supply plate, 46a: lower surface, 46b: gas supply passage, 48: fixing ring 50: support portion, 50a: circulation path, 50b: gas supply path 52: Refrigerant circulation mechanism, 52a: Refrigerant 54: gas supply source, 54a: raw gas 56: high frequency power source, 58: insulating member, 60: opening, 62: support arm, 64: lifting mechanism 66: Controller, S1, S2, S 1´ ,S 2´ :Cross-sectional area

Claims

1. A chuck table that suction-holds a workpiece when the workpiece is processed, A holding surface that suction-holds the workpiece; a cooling passage for allowing a coolant to flow, the cooling passage being provided inside the chuck table; Equipped with The cooling path includes: a supply port for supplying the refrigerant to the cooling passage; an outlet for discharging the refrigerant from the cooling passage; having a chuck table having different cross-sectional areas in a first region and a second region disposed at positions corresponding to two different points on the holding surface between the supply port and the discharge port;

2. the supply port and the discharge port are each provided on another surface of the chuck table that is located on the opposite side to the holding surface in a thickness direction of the chuck table, The cooling path includes: a supply path extending from the supply port along the thickness direction; a discharge path extending from the discharge port along the thickness direction; a parallel passage that is provided so as to extend along the holding surface between the supply passage and the discharge passage when the holding surface is viewed in a plan view, and that connects the supply passage and the discharge passage; Including, 2. The chuck table according to claim 1, wherein the first area and the second area are disposed on the parallel path.

3. The parallel path is a third region and a fourth region that are disposed at a position closer to the supply port than the discharge port in the extending direction of the parallel path and that are adjacent to each other in a direction proceeding from a center portion of the holding surface to an outer periphery of the holding surface; a fifth region and a sixth region that are disposed at a position closer to the discharge port than the supply port in the direction in which the parallel path extends and that are adjacent to each other in a direction proceeding from the center portion to the outer periphery of the holding surface; having 3. The chuck table according to claim 2, wherein a distance between the fifth area and the sixth area is smaller than a distance between the third area and the fourth area.

4. A processing apparatus including the chuck table according to claim 1, a processing unit for processing the workpiece held by suction on the chuck table; a temperature control unit including a heat exchanger for controlling the temperature of the refrigerant; Equipped with The processing apparatus is characterized in that the coolant discharged from the outlet is supplied to the cooling path from the supply port after the temperature of the coolant is adjusted by the temperature adjustment unit.

5. the processing unit is a plasma processing unit; The processing unit includes: a chamber within which the chuck table is disposed; A high frequency power source for generating plasma from a raw material gas; The processing apparatus according to claim 4, further comprising:

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