Electrostatic chuck for plasma etching and plasma etching device

Abstract

To provide a pixel corresponded region and a plasma etching device, capable of realizing a high flatness level processing of a thin thickness insulation material.SOLUTION: An electrostatic chuck 100 for a plasma etching, comprises: an insulation base body 10 having an absorption surface to which a processing material is adhered; a plurality of electrostatic electrodes 20 that is arranged to an insulation base body internal part with a predetermined interval and has an opposite surface that is opposite to the absorption surface; and a conductive member 30 that is arranged at a position between the electrostatic electrodes in view of a direction vertical to the absorption surface on the side opposite to the absorption surface against the plurality of electrostatic electrodes of the insulation base body internal part. When an interval of the two electrostatic electrodes that are closet to the conductive member is x(mm), a distance between the opposite surface of the two electrostatic electrodes and the absorption surface is dSE(mm), and a distance between the conductive member and the absorption surface is dD(mm), and the x, the dSE, and the dD satisfy a relation of dD<A{dSE2+(x / 2)2}1 / 2...(1) in A=2.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to an electrostatic chuck for plasma etching and a plasma etching apparatus. [Background technology]

[0002] Electrostatic chucks are used to fix workpieces in semiconductor processing using plasma. An electrostatic chuck has a structure in which electrodes are arranged in a predetermined pattern in an insulating base, and by applying a DC voltage between the electrodes, an electric attractive force is generated between the workpiece and the electrodes, thereby attracting and holding the workpiece.

[0003] In some electrostatic chucks, an electrode is provided in the insulating base in addition to the electrostatic electrode for attraction, for the purposes of heating the workpiece and increasing the efficiency of etching by plasma.

[0004] For example, Patent Document 1 discloses arranging a resistance heating element inside an electrostatic chuck on the opposite side of the electrostatic electrode from the attracting surface, and Patent Document 2 discloses arranging a heater electrode in a similar position.

[0005] Moreover, Patent Document 3 discloses that an RF electrode is disposed inside the electrostatic chuck on the opposite side to the attracting surface with respect to the electrostatic electrode. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2013-247342 A [Patent Document 2] JP 2015-35448 A [Patent Document 3] JP 2021-2641 A Summary of the Invention [Problem to be solved by the invention]

[0007] While there is a demand for improved processing accuracy in plasma etching, a problem has been encountered when etching thin insulating materials: the etching speed in the depth direction of the processed material varies depending on the position, resulting in low flatness.

[0008] Therefore, an object of the present invention is to solve the above-mentioned problems and to provide an electrostatic chuck which, when applied to a plasma etching apparatus, enables processing of a thin insulating material with high flatness. [Means for solving the problem]

[0009] In the course of research to achieve the above-mentioned object, the present inventors found that the etching rate in the depth direction of a thin insulating workpiece attracted to an electrostatic chuck is higher at a portion overlapping with the electrostatic electrode when viewed from a direction perpendicular to the attracting surface than at other portions. In an electrostatic chuck, electrodes of different polarities are arranged at a predetermined interval from each other in order to prevent short circuits between the electrostatic electrodes. Therefore, in the workpiece attracted to the electrostatic chuck, there are both a portion overlapping with the electrostatic electrode when viewed from a direction perpendicular to the attracting surface, in other words, where the electrostatic electrode is located at the bottom, and a portion not overlapping with the electrostatic electrode, in other words, where the electrostatic electrode is not located at the bottom. This causes a difference in etching rate depending on the position in the workpiece, which inhibits improvement of flatness. Then, as a result of further research based on this knowledge, the inventors found that the above-mentioned problems can be solved by arranging a conductor near the electrostatic electrode so as to cover the inside of the attracting surface together with the electrostatic electrode when viewed from a direction perpendicular to the attracting surface, and thus completed the present invention.

[0010] That is, a first aspect of the present invention comprises an insulating base having an adsorption surface onto which a workpiece is adsorbed, a plurality of electrostatic electrodes arranged at a predetermined interval inside the insulating base and having opposing surfaces facing the adsorption surface, and a conductive member arranged at least at a position between the electrostatic electrodes when viewed from a direction perpendicular to the adsorption surface, on the opposite side of the adsorption surface with respect to the plurality of electrostatic electrodes inside the insulating base, the distance between two of the electrostatic electrodes closest to the conductive member being x (mm), and the distance between the opposing surfaces of the two electrostatic electrodes and the adsorption surface being d SE (mm), the distance between the conductive member and the adsorption surface is d D (mm), the above x and d SE and d D But the relation d D <A{d SE 2 +(x / 2) 2} 1 / 2 …(1) The present invention relates to an electrostatic chuck for plasma etching, which satisfies the above requirement at A=2.

[0011] A second aspect of the present invention provides a method for manufacturing a workpiece comprising: an insulating substrate having an adsorption surface onto which a workpiece material is adsorbed; and a plurality of electrostatic electrodes arranged at predetermined intervals inside the insulating substrate and having opposing surfaces opposed to the adsorption surface, wherein at least half of the plurality of electrostatic electrodes have overlapping portions that are hidden behind the opposing surfaces of adjacent electrostatic electrodes when viewed from a direction perpendicular to the adsorption surface, and the spacing between the opposing surfaces of adjacent electrostatic electrodes is x (mm) and the distance between the adsorption surface and the opposing surfaces is d SE (mm), the maximum distance between the electrostatic electrode having the overlapping portion and the attracting surface in the region between the opposing surface and the overlapping portion is d Omax (mm), the above x and d SE and d Omax But the relation d Omax <A{d SE 2 +(x / 2) 2} 1 / 2 …(2) The present invention relates to an electrostatic chuck for plasma etching, which satisfies the above requirement at A=2.

[0012] Furthermore, a third aspect of the present invention is a plasma etching apparatus including a chamber for accommodating a workpiece therein, a vacuum pump for reducing the pressure inside the chamber, a gas supply means for introducing a process gas into the chamber, a plasma generation electrode for converting the process gas in the chamber into plasma, a high-frequency power source for supplying power to the plasma generation electrode, and the above-mentioned electrostatic chuck for plasma etching that is disposed inside the chamber and attracts and holds the workpiece. Effect of the Invention

[0013] According to the present invention, it is possible to provide an electrostatic chuck that enables processing with a high degree of flatness when applied to a plasma etching apparatus. [Brief description of the drawings]

[0014] [Figure 1] 1 is a cross-sectional view showing an embodiment (first embodiment) of an electrostatic chuck for plasma etching according to a first aspect of the present invention. [Diagram 2] FIG. 2 is a diagram for explaining the positional relationship between an electrostatic electrode and a conductive member in the first embodiment. [Diagram 3] 3 is a cross-sectional view showing an example of an arrangement of conductive members in the first embodiment. FIG. [Figure 4] 4 is a cross-sectional view showing an embodiment (second embodiment) of an electrostatic chuck for plasma etching according to a second aspect of the present invention. FIG. [Diagram 5] 13A to 13C are diagrams for explaining the shape and arrangement of electrostatic electrodes in the second embodiment. [Figure 6] 10A to 10C are cross-sectional views showing examples of the shape and arrangement of electrostatic electrodes in the second embodiment. [Figure 7] 10A to 10C are cross-sectional views showing examples of the shape and arrangement of electrostatic electrodes in the second embodiment. [Figure 8] 10A to 10C are cross-sectional views showing examples of the shape and arrangement of electrostatic electrodes in the second embodiment. [Figure 9]10A to 10C are cross-sectional views showing examples of the shape and arrangement of electrostatic electrodes in the second embodiment. [Figure 10] FIG. 11 is a cross-sectional view showing an embodiment (third embodiment) of a plasma etching apparatus according to a third aspect of the present invention. [Figure 11] 1 is a graph showing the relationship between the etching rate and the thickness of the quartz glass plate, obtained in Experimental Example 1. [Figure 12] 10A to 10C are explanatory diagrams showing a procedure for producing a test electrostatic chuck 1 according to an experimental example 2. [Figure 13] FIG. 2 is a top view showing the placement of a workpiece on a test electrostatic chuck 1. [Figure 14] 14 is a graph showing the results of measuring the height distribution after local plasma etching for region A and region B in FIG. 13. [Figure 15] 11 is a cross-sectional view showing a structure of a test electrostatic chuck 2a according to an experimental example 3. FIG. [Figure 16] 11 is a cross-sectional view showing a structure of a test electrostatic chuck 2b according to an experimental example 3. FIG. [Figure 17] 11 is a cross-sectional view showing a structure of a test electrostatic chuck 2c according to an experimental example 3. FIG. [Figure 18] 1 is a graph showing the results of measuring the height distribution of quartz glass after local plasma etching was performed using each of test electrostatic chucks 2a to 2c. [Figure 19] 11 is a cross-sectional view showing a structure of a test electrostatic chuck 3a according to an experimental example 4. FIG. [Figure 20] 13 is a cross-sectional view showing a structure of a test electrostatic chuck 3b according to Experimental Example 4. FIG. [Figure 21] 11 is a graph showing the results of measuring the height distribution of a quartz plate after local plasma etching was performed using test electrostatic chucks 3a and 3b, respectively. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Each aspect of the present invention will be described in detail below based on one embodiment, but the present invention is not limited to this embodiment.

[0016] One embodiment of the present invention includes each of the following aspects [1] to [8]. [1] An insulating substrate having an adsorption surface on which a workpiece is adsorbed, a plurality of electrostatic electrodes arranged at a predetermined interval inside the insulating substrate and having opposing surfaces facing the adsorption surface, and a conductive member arranged at least at a position between the electrostatic electrodes when viewed from a direction perpendicular to the adsorption surface, on the opposite side of the adsorption surface with respect to the plurality of electrostatic electrodes inside the insulating substrate, the distance between the two electrostatic electrodes closest to the conductive member being x (mm), and the distance between the opposing surfaces of the two electrostatic electrodes and the adsorption surface being d SE (mm), the distance between the conductive member and the adsorption surface is d D (mm), the above x and d SE and d D But the relation d D <A{d SE 2 +(x / 2) 2} 1 / 2 …(1) The present invention provides an electrostatic chuck for plasma etching, which satisfies the above condition A=2. [2] The above x and d SE and d D The electrostatic chuck for plasma etching according to [1] above, wherein the relational expression (1) is satisfied when A=1. [3] The electrostatic chuck for plasma etching according to [1] or [2], wherein the conductive member is grounded. [4] An insulating substrate having an adsorption surface on which a workpiece is adsorbed, and a plurality of electrostatic electrodes arranged at predetermined intervals inside the insulating substrate and having opposing surfaces facing the adsorption surface, wherein more than half of the plurality of electrostatic electrodes have overlapping portions that are hidden behind the opposing surfaces of adjacent electrostatic electrodes when viewed from a direction perpendicular to the adsorption surface, and the interval between the opposing surfaces of adjacent electrostatic electrodes is x (mm), and the distance between the adsorption surface and the opposing surfaces is d SE (mm), the maximum distance between the electrostatic electrode having the overlapping portion and the attracting surface in the region between the opposing surface and the overlapping portion is d Omax (mm), the above x and dSE and d Omax But the relation d Omax <A{d SE 2 +(x / 2) 2} 1 / 2 …(2) The present invention provides an electrostatic chuck for plasma etching, which satisfies the above condition A=2. [5] The above x and d SE and d Omax The electrostatic chuck for plasma etching according to the above [4], wherein the relational expression (2) is satisfied when A=1. [6] A plasma etching apparatus comprising: a chamber for accommodating a workpiece therein; a vacuum pump for reducing the pressure inside the chamber; a gas supply means for introducing a process gas into the chamber; a plasma generation electrode for converting the process gas in the chamber into plasma; a high-frequency power source for supplying power to the plasma generation electrode; and an electrostatic chuck for plasma etching according to any one of [1] to [5], which is disposed in the chamber and adsorbs and holds the workpiece. [7] The plasma etching apparatus according to [6], further comprising a plasma generating tube through which the process gas flows and on whose outer periphery the plasma generating electrode is disposed. [8] The plasma etching apparatus according to [7], configured to generate plasma while sucking in the process gas in the chamber from the tip of the plasma generating tube.

[0017] [Electrostatic chuck] (First embodiment) An embodiment of an electrostatic chuck for plasma etching according to a first aspect of the present invention is shown as a first embodiment in Fig. 1. The electrostatic chuck 100 according to the first embodiment includes an insulating base 10 having an attraction surface 11 to which a workpiece w is attracted, a plurality of electrostatic electrodes 20 arranged at predetermined intervals inside the insulating base 10 and having opposing surfaces 21 opposing the attraction surfaces, and a conductive member 30 arranged at least at a position between the electrostatic electrodes 20 when viewed from a direction perpendicular to the attraction surface 11, on the opposite side of the electrostatic electrodes 20 from the attraction surface 11 inside the insulating base 10.

[0018] The insulating substrate 10 has an adsorption surface 11 onto which the workpiece w is adsorbed. The adsorption surface 11 does not have to be a completely flat or curved surface, and may have fine irregularities, so long as the shape of the adsorption surface 11 allows the workpiece w to be fixed in a predetermined position.

[0019] The insulating substrate 10 has electrical insulation properties, which allows the workpiece w to be attracted and held by electrical attraction while preventing short circuits between the electrostatic electrodes 20 of different polarities when a DC voltage is applied to the electrostatic electrodes 20 described below.

[0020] The material forming the insulating base 10 is not limited as long as it has electrical insulation and excellent shape stability. When the electrostatic chuck 100 is used at room temperature, a resin material such as polyimide or silicone can be used. On the other hand, when the electrostatic chuck 100 is used at high temperature, a ceramic material such as aluminum oxide (Al2O3), aluminum nitride (AlN), silicon nitride (Si3N4), or sialon (Si3N4·Al2O3) can be used.

[0021] A plurality of electrostatic electrodes 20 are arranged at a predetermined interval inside the insulating substrate 10. When a voltage is applied to the electrostatic electrodes 20, the electrostatic electrodes 20 generate an attractive force on the workpiece w, and the workpiece w is attracted to the attraction surface 11. By arranging the electrostatic electrodes 20 at a predetermined interval, it is possible to suppress short circuits between electrodes of different polarities. The interval between the electrostatic electrodes 20 can be appropriately determined according to the magnitude of the DC voltage applied and the material and dimensions of the insulating substrate 10, and can be, for example, 100 μm or more and 5 mm or less. The interval between the electrostatic electrodes 20 may be uniform between all the electrostatic electrodes 20, or may be different for each electrostatic electrode 20. The shape, size and arrangement of the electrostatic electrode 20 are not particularly limited and can be appropriately determined depending on the shape, size and material of the workpiece w and its arrangement. The shape of the opposing surface 21 facing the attracting surface 11 of the electrostatic electrode 20 is preferably parallel to the attracting surface in order to generate a uniform attractive force on the attracting surface.

[0022] The material of the electrostatic electrode 20 is not particularly limited as long as it is conductive and physically and chemically stable in the environment in which the electrostatic chuck 100 is used. When the electrostatic electrode 20 is disposed in the insulating base 10 without sintering, copper (Cu), stainless steel, etc. can be used. On the other hand, when the electrostatic electrode 20 is disposed in the insulating base 10 with sintering, such as when the insulating base 10 is made of a ceramic material, tungsten (W), molybdenum (Mo), etc. can be used.

[0023] Inside the insulating substrate 10, a conductive member 30 is disposed on the opposite side of the electrostatic electrodes 20 from the attracting surface 11, at a position that is at least between the electrostatic electrodes 20 when viewed from a direction perpendicular to the attracting surface 11. The conductive member 30 is spaced apart from the two electrostatic electrodes 20 closest to it by x (mm), and the distance d between the opposing surface 21 of each electrostatic electrode 20 and the attracting surface 11 is d (mm). SE (mm), and the distance between the conductive member 30 and the adsorption surface is d D (mm), x and d SE and d D But the relation d D <A{d SE 2 +(x / 2) 2} 1 / 2 …(1) is placed at a position that satisfies the above condition at A=2. This makes it possible to suppress the variation in etching rate due to position when performing plasma etching, and to improve the flatness of the workpiece w. The above-mentioned relational expression (1) is expressed by the distance d between the attraction surface 11 and the conductive member 30 as shown in FIG. D is the maximum distance {d SE 2 +(x / 2) 2} 1 / 2 This means that the etching time is shorter than A times the distance from the electrostatic electrode 20 on the attraction surface 11. Since the effect of the electrostatic electrode 20 on the plasma becomes smaller at a point on the attraction surface 11 farther from the electrostatic electrode 20, the etching rate becomes smaller. DIf the value of x and d is small and the conductive member 30 is close to the attraction surface 11, the etching rate increases due to the influence of the conductive member 30, compensating for the decrease in the etching rate due to the long distance from the electrostatic electrode 20. As a result, the difference in etching rate within the surface becomes small, and the flatness of the workpiece w is improved. From the viewpoint of significantly improving the flatness of the workpiece w, the above-mentioned x and d SE and d D It is preferable that the relationship (1) is satisfied when the value of A is 1.8, it is more preferable that the relationship (1) is satisfied when the value of A is 1.5, it is even more preferable that the relationship (1) is satisfied when the value of A is 1.3, and it is particularly preferable that the relationship (1) is satisfied when the value of A is 1.

[0024] In order to improve the effect of compensating for the decrease in the etching rate, it is preferable that the conductive member 30 is disposed close to the electrostatic electrode 20. D and the above d SE But, d D ≦d SE It is preferable that the value satisfies +1.0, and d D ≦d SE On the other hand, in order to effectively prevent short circuits between the electrostatic electrodes 20, it is more preferable that the above d D and the above d SE But, d SE +0.01≦d D It is preferable that d SE +0.02≦d D For the reasons described above, it is more preferable that the above d D d SE +0.01≦d D ≦d SE It is preferable that the value satisfies +1.0, and d SE +0.02≦d D ≦d SE It is more preferable to meet +0.5.

[0025] The shape and dimensions of the conductive member 30 are not particularly limited, and may be, for example, a single plate or foil formed on the entire lower part of the electrostatic electrode 20 as shown in Fig. 1. Alternatively, the conductive member 30 may be a plurality of rectangular plates or foils corresponding to the shape and dimensions of the area confirmed between the electrostatic electrodes 20 when viewed from a direction perpendicular to the attraction surface 11 as shown in Fig. 3. When the conductive member 30 is a plurality of rectangular plates or foils, it is preferable that they are arranged over the entire area confirmed between the electrostatic electrodes 20 when viewed from a direction perpendicular to the attraction surface 11 as shown in Fig. 2, but even if they are arranged only in a part of the area, flatness in plasma etching can be improved.

[0026] The material of the conductive member 30 is not particularly limited as long as it has conductivity, and may be the same as or different from the electrostatic electrode 20. When the conductive member 30 is disposed in the insulating base 10 without sintering, copper (Cu), stainless steel, etc. can be used. On the other hand, when the insulating base 10 is made of a ceramic material, for example, and the electrostatic electrode 20 is disposed in the insulating base 10 with sintering, tungsten (W), molybdenum (Mo), etc. can be used.

[0027] The conductive member 30 may be grounded by an electrical connection to the outside of the insulating substrate 10. This makes it possible to suppress the variation in the etching rate depending on the position and improve the flatness of the workpiece w even if the size of the conductive member 30 is small when viewed from the direction perpendicular to the attraction surface 11. Also, when it is necessary to dispose the conductive member 30 away from the facing surface 21 of the electrostatic electrode 20, i.e., when the above-mentioned d D Value of and d SE Even if it is necessary to increase the difference from the value of , the variation in etching rate due to position can be suppressed and the flatness of the workpiece w can be improved compared to the case where the conductive member 30 is not grounded.

[0028] Second embodiment An embodiment of an electrostatic chuck for plasma etching according to a second aspect of the present invention is shown as a second embodiment in Fig. 4. The electrostatic chuck 100 according to the second embodiment includes an insulating base 10 having an attraction surface 11 to which a workpiece w is attracted, and a plurality of electrostatic electrodes 20 arranged at predetermined intervals inside the insulating base 10 and having opposing surfaces 21 opposing the attraction surface 11, and more than half of the plurality of electrostatic electrodes 20 have overlapping portions 22 that are hidden behind the opposing surfaces 21 of adjacent electrostatic electrodes 20 when viewed from a direction perpendicular to the attraction surface 11.

[0029] The insulating substrate 10 may be the same as that in the first embodiment.

[0030] As in the first embodiment, a plurality of electrostatic electrodes 20 are arranged at predetermined intervals inside the insulating substrate 10. The electrostatic electrodes 20 may be made of the same material as in the first embodiment.

[0031] The electrostatic electrode 20 has an opposing surface 21 that faces the attracting surface 11. The opposing surface 21 may be a flat surface or a curved surface, and the angle between the opposing surface 21 and the attracting surface 11 is not limited, but it is preferable that the opposing surface 21 is parallel to the attracting surface 11, since the distance between the opposing surface 21 and the attracting surface 11 is constant and a uniform attractive force can be generated.

[0032] More than half of the electrostatic electrodes 20 have overlapping portions 22 that are hidden behind the opposing surfaces 21 of adjacent electrostatic electrodes 20 when viewed from a direction perpendicular to the attraction surface 11. As shown in FIG. 5, the electrostatic electrodes 20 have a spacing x (mm) between the opposing surfaces 21 of the adjacent electrostatic electrodes 20 and a distance d between the attraction surface 11 and the opposing surfaces 21. SE (mm), the maximum distance between the electrostatic electrode 20 having the overlapping portion 22 and the attraction surface 11 in the region between the facing surface 21 and the overlapping portion 22 is d Omax (mm), the above x and d SE and d Omax But the relation d Omax <A{d SE 2 +(x / 2) 2} 1 / 2 …(2) is satisfied at A=2. When the electrostatic electrode 20 has a shape that satisfies the above relationship, the decrease in etching rate caused by the increase in distance from the opposing surface 21 can be compensated for by the region between the opposing surface 21 and the overlapping portion 22. This makes it possible to suppress the variation in etching rate depending on the position when plasma etching is performed, and improve the flatness of the workpiece material w. From the viewpoint of significantly improving the flatness of the workpiece material w, the above-mentioned x, d SE and d Omax It is preferable that the relationship (1) is satisfied when the value of A is 1.8, it is more preferable that the relationship (1) is satisfied when the value of A is 1.5, it is even more preferable that the relationship (1) is satisfied when the value of A is 1.3, and it is particularly preferable that the relationship (1) is satisfied when the value of A is 1.

[0033] The electrostatic electrode 20 having the overlapping portion 22 is preferably formed by the above-mentioned d Omax and the above d SE But, d Omax ≦d SE It is preferable to arrange the matrix so as to satisfy +1.0, and d Omax ≦d SE On the other hand, in order to effectively prevent short circuits between the electrostatic electrodes 20, the electrostatic electrodes 20 having the overlapping portion 22 are preferably arranged so as to satisfy the above-mentioned d Omax and the above d SE But, d SE +0.01≦d Omax It is preferable to arrange the electrodes so as to satisfy the following: SE +0.02≦d Omax For the reasons described above, it is more preferable to arrange the electrodes so as to satisfy the above d Omax d SE +0.01≦d Omax ≦d SE It is preferable that the value satisfies +1.0, and d SE +0.02≦d Omax ≦d SE It is more preferable to meet +0.5.

[0034] The shape of the lower part of the opposing surface 21 including the overlapping portion 22 is not particularly limited, but from the viewpoint of maintaining a distance between the adjacent electrostatic electrodes 20 and suppressing short circuits, it is preferable that the overlapping portion 22 has a shape corresponding to a recessed portion formed in the lower part of the opposing surface 21 of the adjacent electrostatic electrode 20. Examples of electrostatic electrodes having such shapes include a crank-shaped cross section as shown in Fig. 4, a parallelogram-shaped cross section as shown in Fig. 6, a trapezoid-shaped cross section as shown in Fig. 7, an arch-shaped cross section as shown in Fig. 8, and a shape as shown in Fig. 9.

[0035] [Plasma etching equipment] (Third embodiment) An embodiment of a plasma etching apparatus according to the third aspect of the present invention is shown in FIG. 10 as the third embodiment. The third embodiment is a local plasma etching apparatus, but the plasma etching apparatus according to the present invention is not limited thereto. The plasma etching apparatus 500 according to the third embodiment includes a chamber 51 for accommodating a workpiece w therein, a vacuum pump (not shown) for reducing the pressure inside the chamber 51, a gas supply means 52 for introducing a process gas into the chamber 51, a plasma generation electrode 53 for converting the process gas in the chamber 51 into plasma, a high-frequency power source 54 for supplying power to the plasma generation electrode 53, a plasma generation tube 55 through which the process gas flows and on whose outer periphery the plasma generation electrode 53 is disposed, and an electrostatic chuck 100 for plasma etching according to the first or second embodiment, which is disposed in the chamber 51 and adsorbs and holds the workpiece w.

[0036] The plasma etching apparatus 500 according to the third embodiment includes the electrostatic chuck 100 for plasma etching according to the first or second embodiment, and thus can suppress the variation in etching rate depending on the position and improve the flatness of the workpiece w. This effect is remarkable when the plasma etching apparatus 500 generates microplasma, and is more remarkable when the plasma etching apparatus 500 includes a plasma generating tube 55 in which a process gas flows inside and a plasma generating electrode 53 is arranged on the outer periphery as shown in FIG. 10. Among them, the effect is particularly remarkable when the plasma etching apparatus 500 is a suction plasma etching apparatus configured to generate plasma while suctioning the process gas in the chamber 51 from the tip of the plasma generating tube 55.

[0037] The plasma etching apparatus 500 according to the third embodiment can be suitably used for etching an insulating material having a thickness of 1000 μm or less. When such a material is used as the material to be processed, in the conventional plasma etching apparatus, the difference in etching rate in the depth direction of the material to be processed becomes significant due to the existence of a portion in the attracting surface 11 of the electrostatic chuck 100 where the electrostatic electrode 20 is arranged and a portion where the electrostatic electrode 20 is not arranged directly below the attracting surface 11, making it difficult to obtain a high degree of flatness. However, the plasma etching apparatus 500 according to the third embodiment can perform processing of the material to be processed with a high degree of flatness. The plasma etching apparatus 500 according to the third embodiment has a remarkable effect of improving flatness in etching an insulating material having a thickness of 500 μm or less, and this effect is more remarkable in etching an insulating material having a thickness of 300 μm or less.

[0038] [Plasma etching method] The plasma etching method using the plasma etching apparatus according to the third embodiment can be carried out by the following procedure. First, the workpiece w is placed on the electrostatic chuck 100 arranged in the chamber 51 of the plasma etching apparatus 500. Next, the electrostatic chuck 100 is operated to attract and hold the workpiece w. Next, after exhausting the air in the chamber 51, the gas in the chamber 51 containing the process gas is sucked from the tip of the plasma generating tube 55 while supplying the process gas from the gas supply means 52. Next, power is supplied from the high frequency power source 54 to the plasma generating electrode 53 arranged around the plasma generating tube 55 to generate plasma and etch the workpiece w.

[0039] The plasma etching method using the plasma etching apparatus according to the third embodiment is suitable for etching a workpiece made of an insulating material having a thickness of 1000 μm or less. Examples of insulating materials include quartz, crystal, lithium niobate, and various glass materials. In etching such workpieces, the generated plasma is easily affected by the electrostatic electrodes in the electrostatic chuck, so that the flatness is easily reduced in the plasma etching method using the conventional electrostatic chuck and the plasma etching apparatus equipped with the same. In contrast, in the plasma etching method using the plasma etching apparatus according to the third embodiment, the generated plasma is not easily affected by the arrangement of the electrostatic electrodes, so that processing with a high flatness is possible. The thickness of the workpiece is more preferably 500 μm or less, and even more preferably 300 μm or less. Note that when the workpiece is more than 1000 μm thick, is conductive, or has a conductive film on the surface of the insulating material, the electrostatic electrodes in the electrostatic chuck do not affect the etching rate or have only a slight effect on the etching rate. For this reason, no significant effect is obtained by using the plasma etching apparatus according to the third embodiment, but processing with a high degree of flatness is possible, similar to the case of a plasma etching apparatus equipped with a conventional electrostatic chuck. EXAMPLES

[0040] Each embodiment of the present invention will be described in more detail below based on examples, but the present invention is not limited to these examples in any way.

[0041] [Experimental Example 1] As Experimental Example 1, the following experiment was conducted to examine the effect of a conductive material placed on the opposite side to the surface being etched on the etching rate in the depth direction during plasma etching of an insulating material.

[0042] First, quartz glass plates with different thicknesses (thickness: 100 μm, 170 μm, 300 μm, 500 μm, 1000 μm, 3000 μm, and 5000 μm) were prepared, and each glass plate was fixed on an aluminum sample stage with polyimide (Kapton) tape. Next, the sample stage on which the glass plate was fixed was placed in a chamber of a suction plasma etching device equipped with a plasma generating tube with a diameter of 4 mm. After evacuating the chamber, the gas in the chamber containing the process gas was sucked from the tip of the plasma generating tube while supplying carbon tetrafluoride (CF4) as a process gas at a flow rate of 90 SCCM from the gas supply means. At this time, the pressure in the chamber was 800 Pa, and the back pressure of the plasma generating tube was 500 Pa. The distance between the tip of the plasma generating tube and the quartz plate was 0.2 mm, and power was supplied from an RF power source with an output of 50 W to the plasma generating electrode arranged around the plasma generating tube, generating plasma to etch the quartz plate. The etching time was 600 seconds.

[0043] The etching depth of each glass plate after etching was measured, and the etching rate was calculated by dividing the etching depth by the etching time. The relationship between the etching rate and the thickness of the glass plate is shown in Figure 11.

[0044] 11 shows that there is almost no difference in the etching rate between 3000 μm thick glass plates and 5000 μm thick glass plates, and that for glass plates with a thickness of 1000 μm or less, the etching rate increases significantly as the plate thickness decreases. These results show that in etching an insulating material with a thickness of 3000 μm (3 mm) or less, if there are areas on the opposite side to the surface to be etched where there are areas where there is a conductive material and areas where there is not, the flatness decreases due to the difference in etching rate, and that this decrease in flatness becomes more pronounced as the thickness of the material being processed becomes thinner.

[0045] [Experimental Example 2] In order to confirm the effect of improving the flatness by the conductive member in the electrostatic chuck according to the first embodiment, the following experiment was carried out.

[0046] (Preparation of Test Electrostatic Chuck 1) First, as shown in FIG. 12(a), a copper foil M1 having a length of 30 mm, a width of 15 mm, and a thickness of 10 μm was placed on a polyimide (Kapton) tape T1 having a length of 60 mm, a width of 20 mm, and a thickness of 35 μm. Next, as shown in FIG. 12(b), a polyimide tape T2 having the same width as the polyimide tape was attached to the polyimide tape T1 and the copper foil M1. At this time, the attachment position was adjusted so that the center of the length of the polyimide tape T2 overlaps with one end of the length of the copper foil M1. Next, as shown in FIG. 12(c), a copper foil M2 having a length of 40 mm, a width of 15 mm, and a thickness of 10 μm and a slit having a width of 1 mm and a length of 20 mm was formed in the center of the width direction was placed on the polyimide tape T2. At this time, the position of the copper foil M2 was adjusted so that the center of the length of the slit overlaps with one end of the copper foil M1 in the length direction. 12(d), a polyimide tape T3 having a width of 20 mm and a thickness of 35 μm was attached so that the vicinity of one end of the copper foil M2 was exposed, thereby obtaining a test electrostatic chuck 1. In this test electrostatic chuck 1, the polyimide tapes T1 to T3 correspond to the insulating substrate, the copper foil M1 corresponds to the conductive member, and the copper foil M2 corresponds to the electrostatic electrode. D =0.080mm, d SE= 0.035 mm, x = 1 mm, so the relation d D <A{d SE 2 +(x / 2) 2} 1 / 2 However, this holds true not only when A=2, but also when A=1.

[0047] (Plasma Etching Test) A quartz plate having a thickness of 300 μm as the workpiece w was placed on the fabricated test electrostatic chuck 1 so as to overlap the copper foil M2 as shown in FIG. 12, and the workpiece was placed in a chamber of a suction plasma etching apparatus equipped with a plasma generating tube having a diameter of 4 mm. Here, the region indicated by A in FIG. 13 is a portion where a conductive member is not arranged under the electrostatic electrode, and corresponds to the electrostatic chuck according to the comparative example of the present invention. The region indicated by B in FIG. 13 is a portion where a conductive member is arranged under the electrostatic electrode, and corresponds to the electrostatic chuck according to the embodiment of the present invention. After evacuating the chamber, the gas in the chamber including the process gas was sucked from the tip of the plasma generating tube while supplying carbon tetrafluoride (CF4) as a process gas from the gas supply means at a flow rate of 55 SCCM. At this time, the pressure in the chamber was set to 800 Pa, and the back pressure of the plasma generating tube was set to 500 Pa. The distance between the tip of the plasma generating tube and the quartz plate was set to 0.2 mm, and 50 W of power was supplied from an RF power source to the plasma generating electrodes arranged around the plasma generating tube to generate plasma and etch the quartz plate. The etching time was 600 seconds.

[0048] (Measurement of etching depth) The height distribution in the width direction (arrow direction in FIG. 13) of the slit in the test electrostatic chuck 1 was measured for the regions A and B of the etched quartz plate using a laser microscope (Keyence Corporation, VK-X100 model). The results are shown in FIG.

[0049] 14, in region B, where a conductive member is placed close to the lower part of the electrostatic electrode and where a conductive material is present even in positions where the electrostatic electrode is not placed when viewed from a direction perpendicular to the attracting surface, the distribution of the etching depth is found to be within an extremely narrow range (3.21 μm). In contrast, in region A, where no conductive member is placed below the electrostatic electrode, the distribution of the etching depth is found to be broad (9.75 μm). From these results, it can be said that an electrostatic chuck in which a conductive member is placed between the electrostatic electrodes when viewed from a direction perpendicular to the attracting surface and at a position slightly away from the electrostatic electrodes with respect to the attracting surface can perform processing with a high degree of flatness when used for plasma etching.

[0050] [Experimental Example 3] In order to compare the machining accuracy in the electrostatic chuck according to the first embodiment depending on whether or not the conductive member is grounded, the following experiment was carried out.

[0051] (Preparation of test electrostatic chuck 2a) First, a polyimide (Kapton) tape T1 having a length of 20 mm, a width of 20 mm, and a thickness of 35 μm was prepared, and a copper foil M having a length of 15 mm, a width of 15 mm, and a thickness of 10 μm was placed on the polyimide tape T1. Next, a polyimide tape T2 having the same dimensions as the polyimide tape T1 was placed on the copper foil M so as to overlap the polyimide tape T1, thereby obtaining a test electrostatic chuck 2a. The structure of the test electrostatic chuck 2a is shown in FIG. 15.

[0052] (Preparation of test electrostatic chuck 2b) A test electrostatic chuck 2b was obtained in the same manner as the test electrostatic chuck 2a, except that the dimensions and shape of the copper foil M in the test electrostatic chuck 2a were set to a circle with a diameter of 2 mm and the copper foil M was connected to earth. The structure of the test electrostatic chuck 2b is shown in FIG.

[0053] (Preparation of test electrostatic chuck 2c) A test electrostatic chuck 2c was obtained in the same manner as the test electrostatic chuck 2b, except that the copper foil M was not connected to earth. The structure of the test electrostatic chuck 2c is shown in FIG.

[0054] (Plasma Etching Test) For each of the test electrostatic chucks 2a to 2c, a plasma etching test was performed in the same manner as in Experimental Example 1, except that a quartz plate having a thickness of 300 μm was used as the workpiece, the flow rate of the process gas was set to 90 SCCM, and the output of the RF power supply was set to 40 W.

[0055] (Measurement of etching depth) For each etched quartz plate, the height distribution in the vicinity of the etched portion was measured in the same manner as in Experimental Example 1. The results are shown in Figure 18. The results shown in the figure are the measurement results in the direction of the arrows in Figures 15 to 17.

[0056] As can be seen from FIG. 18, when the conductive member placed in the electrostatic chuck is grounded, it exhibits an etching-promoting effect even if its dimensions are small, suppresses the variation in etching rate due to position, and contributes to improving the flatness of the workpiece material.

[0057] [Experimental Example 4] In order to confirm the effect of the shape of the electrostatic electrode in the electrostatic chuck according to the second embodiment, the following experiment was carried out.

[0058] (Preparation of test electrostatic chuck 3a) First, a polyimide (Kapton) tape T1 having a thickness of 35 μm and a copper foil M having a thickness of 10 μm were laminated together to prepare a laminate. Next, the laminate was cut into strips having a width of about 1.5 mm. Next, as shown in FIG. 19, each of the cut strips was attached to a polyimide tape T2 having a thickness of 35 μm with the copper foil M side facing down and partially overlapping in the width direction, to obtain a test electrostatic chuck 3a. In this test electrostatic chuck 3a, the polyimide tapes T1 and T2 correspond to the insulating substrate, and the copper foil M corresponds to the electrostatic electrode. And, of the copper foil M, the one other than the one arranged on the far right corresponds to the electrostatic electrode having an overlapping portion. In addition, this test electrostatic chuck 1 has a thickness of d D = 0.099 mm, d SE= 0.049 mm, x = 0.75 mm, so the relation d Omax <A{d SE 2 +(x / 2) 2} 1 / 2 However, this holds true not only when A=2, but also when A=1.

[0059] (Preparation of test electrostatic chuck 3b) First, a copper foil M having a thickness of 10 μm was cut into strips having a width of about 1 mm. Next, each of the cut strips was attached to a polyimide tape T1 having a thickness of 35 μm at intervals of 2 mm, as shown in FIG. 20, and then a polyimide tape T2 of the same size was attached from above to obtain a test electrostatic chuck 3b.

[0060] (Plasma Etching Test) A plasma etching test was carried out in the same manner as in Experimental Example 1 for each of the test electrostatic chucks 3a and 3b.

[0061] (Measurement of etching depth) For the etched quartz plate, the height distribution in the width direction of the copper foil (the direction of the arrows in FIGS. 19 and 20) was measured in the same manner as in Experimental Example 1. The results are shown in FIG.

[0062] 21, it can be seen that the etching depth distribution is within an extremely narrow range in the test electrostatic chuck 3a in which more than half of the electrostatic electrodes have overlapping portions that are hidden behind the opposing surfaces of adjacent electrostatic electrodes when viewed from a direction perpendicular to the chucking surface, and the overlapping portions are disposed close to the opposing surfaces of the other electrostatic electrodes. In contrast, it can be seen that the etching depth distribution range is wide in the test electrostatic chuck 3b in which the electrostatic electrodes do not have overlapping portions. From these results, it can be said that an electrostatic chuck in which more than half of the electrostatic electrodes have overlapping portions that are close to the opposing surfaces of adjacent electrostatic electrodes can perform processing with a high degree of flatness when used for plasma etching. [Industrial Applicability]

[0063] According to the present invention, it is possible to provide an electrostatic chuck that enables processing with a high degree of flatness when applied to a plasma etching apparatus. Therefore, the present invention is useful for forming a plasma etching apparatus that performs high-precision processing. In particular, the present invention is useful in a local plasma etching apparatus that generates plasma inside a plasma generating tube, particularly a suction plasma etching apparatus, in that extremely high-precision processing can be performed regardless of the arrangement of the electrostatic electrodes in the electrostatic chuck. [Explanation of symbols]

[0064] 100 (for plasma etching) Electrostatic chuck 10 Insulating substrate 11 Adsorption surface 20 Electrostatic Electrode 21 Opposite Surface 22 Overlap 30 Conductive materials 500 Plasma Etching Equipment 51 Chamber 52 Gas supply means 53 Plasma generating electrode 54 High frequency power supply 55 Plasma Generator Tube w Work material

Claims

1. an insulating substrate having an adsorption surface onto which a workpiece material is adsorbed; are arranged at predetermined intervals within the insulating base, The adsorption surface has an opposing surface facing the adsorption surface. A plurality of electrostatic electrodes; and a conductive member disposed at least at a position between the electrostatic electrodes when viewed from a direction perpendicular to the attracting surface, on the opposite side of the attracting surface with respect to the plurality of electrostatic electrodes, inside the insulating base; Equipped with The distance between the two electrostatic electrodes closest to the conductive member is x (mm), and the distance between the opposing surfaces of the two electrostatic electrodes and the attraction surface is d. ＳＥ (mm), the distance between the conductive member and the attraction surface is d Ｄ (mm), the x and d ＳＥ and d Ｄ But the relation d Ｄ <A{d ＳＥ 2 +(x / 2) ２ } 1 / 2 …(1) is satisfied at A=2. Electrostatic chuck for plasma etching.

2. The x and d ＳＥ and d Ｄ 2. The electrostatic chuck for plasma etching according to claim 1, wherein said relational expression (1) is satisfied when A=1.

3. 2. The electrostatic chuck for plasma etching of claim 1, wherein the conductive member is grounded.

4. An insulating substrate having an adsorption surface onto which a workpiece material is adsorbed; and are arranged at predetermined intervals within the insulating base, The adsorption surface has an opposing surface facing the adsorption surface. Multiple electrostatic electrodes Equipped with At least half of the plurality of electrostatic electrodes have overlapping portions that are hidden behind the opposing surfaces of adjacent electrostatic electrodes when viewed in a direction perpendicular to the attraction surface, and The distance between the opposing surfaces of the adjacent electrostatic electrodes is x (mm), and the distance between the attraction surface and the opposing surface is d ＳＥ (mm), the maximum distance between the electrostatic electrode having the overlapping portion and the attracting surface in the region between the opposing surface and the overlapping portion is d Ｏｍａｘ (mm), the x and d ＳＥ and d Ｏｍａｘ But the relation d Ｏｍａｘ <A{d ＳＥ 2 +(x / 2) ２ } 1 / 2 …(2) is satisfied at A=2. Electrostatic chuck for plasma etching.

5. The x and d ＳＥ and d Omax 5. The electrostatic chuck for plasma etching according to claim 4, wherein said relational expression (2) is satisfied when A=1.

6. a chamber for containing the material to be processed therein; a vacuum pump for reducing the pressure inside the chamber; A gas supply means for introducing a process gas into the chamber; a plasma generating electrode for generating plasma from the process gas in the chamber; A high frequency power source that supplies power to the plasma generating electrode; and 6. The electrostatic chuck for plasma etching according to claim 1, which is disposed in the chamber and attracts and holds a workpiece. A plasma etching apparatus comprising:

7. 7. The plasma etching apparatus according to claim 6, further comprising a plasma generating tube through which the process gas flows and on the outer periphery of which the plasma generating electrode is disposed.

8. 8. The plasma etching apparatus according to claim 7, configured to generate plasma while sucking the process gas in the chamber from the tip of the plasma generating tube.

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