KR100712224B1 - Cooling passage - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic chuck of a plasma processing apparatus, comprising a heat transfer gas supply flow path and a cooling flow path in an electrostatic chuck installed in a sealed chamber, for uniformly injecting heat transfer gas to a substrate and efficiently cooling the substrate. It relates to a structure of an electrostatic chuck and a plasma processing apparatus using the same. As described above, the overall flow of the heat transfer gas may be uniformly formed and uniformly sprayed onto the substrate, and the cooling efficiency may be increased by increasing the contact area of the cooling water through the cooling passage.

Heat transfer gas, cooling flow path, plasma, electrostatic chuck, ceramic sheet

Description

Cooling flow path {COOLING PASSAGE}

1 is a cross-sectional view showing a general plasma processing apparatus.

Figure 2 is an enlarged cross-sectional view showing the structure of a conventional electrostatic chuck.

3 is a cross-sectional view of a plasma processing apparatus according to the present invention.

4 is an enlarged cross-sectional view of an electrostatic chuck in accordance with the present invention.

5 is a plan view showing a heat transfer gas flow path of the electrostatic chuck according to the present invention.

6A and 6B are plan views illustrating gas ejection holes formed in the ceramic sheet according to the present invention.

FIG. 6C is a cross-sectional view taken along the line A-A of FIG. 6B.

6D is a cross-sectional view taken along the line A-A of FIG. 6B.

FIG. 6E is a cross-sectional view taken along the line B-B in FIG. 6B.

7A to 7E are plan views illustrating cooling passages inside the electrostatic chuck body according to the present invention.

8 is a plan view illustrating a temperature measurement position where temperature is measured according to the flow of cooling water.

9 shows the temperature of the surface of the electrostatic chuck taken with an infrared camera.

<Description of the code | symbol about the principal part of drawings>

10, 110: substrate 12, 112: upper electrode portion

14, 114: lower electrode portion 16, 116: lower electrode

18: electrostatic chuck 20, 120: gas supply source

22a, 22b, 122a, 122b: high frequency power supply 24, 124: vacuum chamber

26, 126: insulator 30, 130: DC high voltage power supply

32, 132: heat transfer gas supply line 34, 134: exhaust line

118: electrostatic chuck body 119: ceramic sheet

150: inner inlet 152: inner passage

154: outer passage 162a: outer cooling passage

162b: inner cooling passage 164a: first opening

164b: second opening 166: projection

The present invention relates to an electrostatic chuck and a plasma processing apparatus using the same, and more particularly, to an electrostatic chuck and a plasma processing apparatus using the same to control the flow of cooling water and the flow of heat transfer gas.

As the semiconductor and display industry develops, processing of substrates such as wafers and glass is also progressing toward minimizing and integrating desired patterns in a limited area. Accordingly, plasma processing technology is widely used when growing or etching thin films on substrates. It is utilized. Plasma treatment is widely used in processing processes of semiconductors, display substrates, etc. due to the advantages of controlling the process at high density. The plasma processing apparatus is classified into a single sheet type and a batch type apparatus. In the single layer type plasma processing apparatus, electrodes are disposed up and down in a vacuum chamber to generate a plasma by applying high frequency power between both electrodes.

Referring to FIG. 1, a general sheet type semiconductor plasma processing apparatus includes an upper electrode portion 12 and a lower electrode portion 14 on which a semiconductor substrate 10, which is an object to be processed, is disposed in a vacuum chamber and disposed opposite to the upper electrode portion 12. ), The lower electrode portion 14 includes a lower electrode 16 and an electrostatic chuck 18 to which power is applied. The upper electrode portion 12 and the lower electrode portion 14 are spaced apart from each other at predetermined intervals to face each other. Gas is supplied from the gas supply source 20 through the shower head (not shown), and high frequency power matched from external high frequency power supplies 22a and 22b is applied to the upper and lower electrode portions 12 and 14. Gas is ionized in the vacuum chamber 24 by this high frequency electric power, and a high density plasma is generated in the space between the upper and lower electrode parts 12 and 14. Here, the electrostatic chuck 18 for mounting the substrate 10 is provided above the lower electrode portion 14, and the lower portion of the lower electrode portion 14 is formed of an insulator 26.

When plasma is generated by applying the high frequency power supplies 22a and 22b to the upper and lower electrode portions 12 and 14, the electrostatic chuck 18 has a predetermined DC high voltage power supply 30 for electrostatically adsorbing the substrate 10. DC voltage is applied through the substrate 10 is fixed to the electrostatic chuck (18). If the magnitude of the DC voltage applied here is out of a certain range, it causes damage to the substrate 10 when the substrate 10 is separated from the electrostatic chuck 18 after the process. In the micro space between the substrate 10 and the electrostatic chuck 18, a heat transfer gas, for example helium gas, is supplied through the heat transfer gas supply line 32 to facilitate temperature control of the substrate 10. After a certain period of time, the heat transfer gas is exhausted through the exhaust line 34, and the substrate 10, which has been electrostatically adsorbed to the electrostatic chuck 18, is desorbed by the negative DC high voltage power supply 30 and the vacuum chamber. (24) It is transported out.

When etching the substrate 10 fixed to the upper surface of the electrostatic chuck 18, a high temperature heat is generated on the substrate 10 and the substrate 10 is exposed to the plasma so that the temperature is continuously raised. A certain amount of heat transfer gas is supplied through the line 32 to move along the flow path formed on the surface of the electrostatic chuck 18 to remove heat generated in the substrate 10 during etching.

Figure 2 is an enlarged cross-sectional view showing the structure of a conventional electrostatic chuck. The electrostatic chuck 18 has a coolant movement path 27 through which coolant can be circulated, and the coolant serves to cool the electrostatic chuck 18 to a predetermined temperature. In addition, an electrode plate 17 is provided inside the electrostatic chuck 18. A DC voltage 30 is applied to the electrode plate 17 in order to prevent shaking or detachment of the substrate and to electrostatically adsorb the substrate 10 to the electrostatic chuck 18. A chiller 28 is located outside the semiconductor device to provide cooling water to the electrostatic chuck 18. The electrostatic chuck body is usually made of aluminum, and ethylene glycol is generally used as the cooling water. However, the conventional cooling water supply method does not uniformly cool the electrostatic chuck, there is a problem that the cooling efficiency is lowered.

In addition, the conventional electrostatic chuck 18 forms a heat transfer gas inlet and a radial flow path at a central portion thereof, and the heat transfer gas injected into the electrostatic chuck 18 has a flow path formed on the surface of the electrostatic chuck 18. Move along. However, since the heat transfer gas flow path of the electrostatic chuck 18 is radially formed from the center to the edge and becomes wider toward the edge of the electrostatic chuck 18, the heat transfer gas passes through a long flow path during the processing of the substrate 10. Moving to the edges takes a long time, which results in temperature imbalances in the center and edge of the substrate 10. That is, when the heat transfer gas injected into the electrostatic chuck 18 is not uniformly distributed and the cooling efficiency is lowered, the temperature of the substrate 10 rises and the surface temperature is locally nonuniform. This phenomenon worsens as the surface area of the substrate 10 increases. This results in problems such as lowering of the uniformity of the process, deformation of the photoresist film, lowering of the etching rate and reproducibility, and failing to obtain a desired etching rate profile, line width and film thickness.

Accordingly, an object of the present invention is to provide an electrostatic chuck capable of uniformly forming the entire flow of heat transfer gas and a plasma processing apparatus using the same.

In addition, an object of the present invention is to provide an electrostatic chuck capable of uniformly ejecting heat transfer gas to the back surface of the substrate through a supply flow path and a plasma processing apparatus using the same.

In addition, an object of the present invention is to provide an electrostatic chuck and a plasma processing apparatus using the same, by improving the structure and shape of the cooling channel in the flow of the cooling water to increase the contact area of the cooling water.

In order to achieve the above object, the present invention provides an electrostatic chuck on which a heat transfer gas supply flow path is formed on a substrate, an inner inlet formed in a central portion of the electrostatic chuck, and an annular inner flow path connected to the inner inlet; It consists of the annular outer flow path formed independently in the outer side of an inner flow path, without communicating with it, and the outer inflow port formed on the said outer flow path. The inner passage is provided in a plurality spaced apart radially, which is in communication with each other. A plurality of outer flow paths are provided radially spaced apart, which communicate with each other. A plurality of inner and outer inlets are provided in the inner and outer flow passages, and the upper portion of the electrostatic chuck includes a plurality of radially spaced annular flow passages and a ceramic sheet including gas ejection holes formed in the annular flow passages. The ceramic sheet provided on the top of the electrostatic chuck so that the heat transfer gas can be uniformly sprayed on the substrate is composed of a plurality of radially spaced annular flow paths and a gas ejection hole formed in the annular flow path. The annular flow path corresponds to the shape of the gas supply flow path of the electrostatic chuck, and the gas blowing hole is formed in a circular shape through the bottom surface of the annular flow path. The gas blowing hole is formed to include a through hole formed in a circular shape on the bottom surface of the annular flow path and a pipe extending thereon. In the electrostatic chuck, the electrostatic chuck includes a first opening formed on one side of the edge, a second opening formed on one side of the central region of the electrostatic chuck, and a spiral cooling passage connecting the first and second openings. The spiral cooling flow path has a shape that rotates at least two rotations, and at least a part of the spiral cooling flow path is provided with a protrusion. The first opening is the inlet and the second opening is the outlet. A plurality of protrusions may be formed, and each of the protrusions may include a cylinder, an elliptic cylinder, and a polygonal pillar. The protrusion may be configured in one or more fence shapes along the cooling passage, the fence may comprise a corrugated shape. The heat transfer gas supply passage of the electrostatic chuck body, the heat transfer gas ejection structure of the ceramic sheet, and the cooling passage structure inside the electrostatic chuck may be independently applied to the plasma processing apparatus, and two or more may be variously combined and applied to the plasma processing apparatus. .

3 is a cross-sectional view schematically showing a plasma processing apparatus according to the present invention.

Referring to FIG. 3, in the plasma processing apparatus of the present invention, an upper electrode portion 112 and a lower electrode portion on which the semiconductor substrate 110 which is an object to be processed are mounted in the vacuum chamber 124 are disposed opposite to the upper electrode portion 112. 114 is provided. The lower electrode part 114 includes a lower electrode 116 to which power is applied, and electrostatic chucks 118 and 119.

A substrate loading / unloading port 115 is formed on the sidewall of the vacuum chamber 124, thereby carrying the substrate 110 in and out. In addition, an exhaust system such as a vacuum pump 113 may be connected to the sidewall or the bottom of the vacuum chamber 124, and exhaust may be performed therefrom to maintain the inside of the vacuum chamber 124 at a desired degree of vacuum.

The upper electrode portion 112 may be supplied with RF power through the RF power supply 122a and the impedance matcher 123a, and may include a shower head (not shown) capable of introducing a reaction gas into the vacuum chamber 124. Can be installed.

When the high frequency power source 122b is connected to the lower electrode part 114 which is spaced apart from the upper electrode part 112 by a predetermined distance and connected to each other, the lower electrode part ( The high frequency power may be supplied to the 114 by the high frequency power source 122b. A ground support member 127 and an insulating member 126 are installed at the bottom of the lower electrode 114, and an electrostatic force, which is a holding means for holding the substrate 110, for example, a semiconductor wafer, is disposed on the upper surface of the lower electrode 114. The chucks 118 and 119 are installed.

The electrostatic chucks 118 and 119 are formed in substantially the same shape and size as the shape of the substrate 110 to be mounted on the upper surface, but the shape is not particularly limited. For example, when the substrate 110 is a semiconductor wafer, it is preferable that the diameter of the upper surface of the substrate 110 be similar to that of the wafer. The electrostatic chucks 118 and 119 are provided with a conductive member (not shown) inside, and the conductive member is connected to the high voltage direct current power supply 130 to hold and hold the substrate 110 by applying a high voltage. In this case, the electrostatic chucks 118 and 119 may maintain the substrate 110 by mechanical force in addition to the electrostatic force, and the focus ring 113 may be provided outside the electrostatic chucks 118 and 119.

4 shows an enlarged cross-sectional view of an electrostatic chuck in accordance with the present invention. The electrostatic chucks 118 and 119 are composed of an electrostatic chuck body 118 and a ceramic sheet 119 bonded to the upper portion of the body. In this case, the electrode plate 117 of the conductive member to which the DC power is applied is inserted in the ceramic sheet 119, and the aluminum body 118 may be coated with an aluminum oxide layer (Al ₂ O ₃ ). The electrostatic chuck body 118 is provided with a plurality of heat transfer gas supply holes, and the gas supply holes are connected to the gas supply line 132 passing through the lower electrode and the insulating members 116 and 126. The gas supply line 132 may be connected to a gas supply source 133 outside the vacuum chamber 124, and heat transfer gas may be supplied from the gas supply source 133.

In addition, a cooling channel 162 connected to the cooling water inlet 164a and the outlet 164b is formed in the electrostatic chucks 118 and 119 to allow the cooling water to flow. Outside the vacuum chamber 124, a chiller 128 is connected to the cooling channel 162 through the coolant inlet and outlet lines 129a and 129b to provide the coolant to the electrostatic chuck. The upper surface of the electrostatic chuck body 118 is formed with an inner inlet 150 and an inner passage and an outer passage 152, 154 connected to the gas supply line 132. In addition, the ceramic sheet 119 covering the top surface of the electrostatic chuck is generally bonded to the top of the electrostatic chuck body 118 by low temperature compression using a thermoplastic polyimide adhesive.

5 is a plan view showing a heat transfer gas flow path formed on the upper surface of the electrostatic chuck in accordance with the present invention.

Referring to the drawings, the electrostatic chuck body 118 is formed with an inner inlet 150, an inner passage 152, an outer passage 154, and an outer inlet 156. The inner inlets 150 formed in the central portion of the electrostatic chuck body 118 are radially connected to the plurality of inner flow passages 152 each formed in an annular shape and radially communicating with each other, and the outer inlets 156 are inward. It is formed in the outer flow path 154 which is formed independently without communicating with the flow path 152. At this time, the inner inlet 150 and the outer inlet 156 is connected to the gas supply line 132. At this time, one or more outer passages 154 may be formed as necessary, and when one or more are formed, the outer passages 154 may be formed to communicate with each other. In addition, in the case of the inner flow path 152, the shape in which three annular flow paths are connected to each other, but the number thereof may be two or less or four or more. One or more inner and outer inlets 150 and 156 formed in the inner channel and the outer channel 152 and 154 while penetrating the electrostatic chuck body 118 are formed in the inner channel 152 and the outer channel 154, respectively. May be

When the heat transfer gas is injected from the inner inlet 150 at the center of the electrostatic chuck body 118, it is spread in the inner flow path 152 which is formed to communicate radially with each other, and is formed separately when the heat transfer gas is injected from the outer inlet 156. Gas spreads through the outer flow path 154. That is, the heat transfer gas is supplied to the surface of the electrostatic chuck body 118 through an independent path to effectively remove the temperature imbalance at the center and the edge of the electrostatic chuck and increase the cooling efficiency.

6A is a plan view illustrating a gas flow path and a gas ejection hole formed on a surface of a ceramic sheet. As shown in the figure, the ceramic sheet 119 forms a concentric concentric radially spaced gas flow path 158. The flow path 158 is formed with a myriad of gas blowing holes in a position and shape corresponding to the annular portion of the gas flow path 158 formed on the surface of the electrostatic chuck body 118. In addition, as shown in FIG. 6B, a plurality of protrusions 159 may be formed in the gas flow path 158 so as not to interfere with the gas ejection holes 160.

FIG. 6C is a cross-sectional view taken along the line A-A of FIG. 6B, and FIG. 6D is a modification of FIG. 6C. As illustrated in FIG. 6C, the gas ejection hole 160 may be formed through the bottom of the flow path 158 in a circular shape, or the through hole formed on the bottom surface of the flow path 158 and the pipe extending thereon as shown in FIG. 6D. 161 may be shaped to include. When the extension pipe 161 is formed as shown in FIG. 6D, the contact surface between the substrate 110 and the ceramic sheet 119 is widened to facilitate electrostatic adsorption, and the inner and outer inlets 150 and 156 of the electrostatic chuck 118 are provided. Through the gas injected there is an effect that can be ejected at a high speed. In addition, the gas ejection hole 160 may have various shapes that widen the contact surface of the substrate 110 and the ceramic sheet 119 in addition to the extension pipe 161. FIG. 6E is a cross-sectional view taken along the line B-B in FIG. 6B, and has an effect of enlarging the contact surface that the gas contacts while moving.

7A to 7E show cooling passages inside the electrostatic chuck body according to the present invention. Referring to the drawings, the first opening 164a and the second opening 164b are formed at one side of the edge of the electrostatic chuck body 118 and one side of the central region, respectively. Is formed. The first opening 164a is an inlet, the second opening 164b is an outlet, and the inlet and outlet are connected to an external chiller through the coolant inlet and outlet lines 129a and 129b. The cooling passage includes an outer cooling passage 162a and an inner cooling passage 162b, and after the cooling water from the inlet 164a rotates about one circumferential direction along the outer cooling passage 162a, the inner cooling passage 162b. 1 turn again in the circumferential direction. At this time, a plurality of protrusions 166 are installed on the outer cooling flow path 162a to maximize the cooling efficiency of the electrostatic chucks 118 and 119 by enlarging the contact surface that the cooling water contacts while moving. Of course, the plurality of protrusions may be installed on the inner cooling passage 162b.

The plurality of protrusions 166 installed in the cooling passage may be formed in the shape of a cylinder or a polygonal pillar, as shown in FIGS. 7C and 7D, and in addition, an elliptic pillar may be formed. In addition, as shown in Figure 7b, it can be formed in the shape of the fence formed continuously along the outer cooling passage 162a, in order to increase the contact area with the cooling water, as shown in Figure 7e, it can form a cooling passage structure in a corrugated shape. have. Also, the number of the plurality of protrusions 166 is not limited. The above method can uniformly cool a large area compared to the conventional method in which each of the inlet 164a and the outlet 164b flows in and out.

Cooling water flows in from the inlet port 164a, and moves along the outer cooling flow path 162a through the cooling flow path, and then flows into the inner cooling flow path 162b from the outer cooling flow path 162a. In addition, the coolant flowing into the inner cooling passage 162b flows around the inner cooling passage 162b along the inner cooling passage 162b and then flows out to the outlet 164b formed in a portion of the inner cooling passage 162b. The inlet 164a and the outlet 164b of the cooling water may be formed by changing their positions. In addition, although the cooling flow path was comprised by the spiral which rotates two rotations, it can form by three or more rotation spirals.

8 shows a temperature measurement position where temperature is measured according to the flow of cooling water. Referring to the drawings, the temperature of the electrostatic chuck was measured at nine positions along the cooling flow path of the electrostatic chuck.

time Set temperature (℃) One 2 3 4 5 6 7 8 9 0 50 48.3 48.2 48 48.3 47.8 47.3 47.4 47.6 47.6 One 40 42 40.9 40.8 40.7 40.7 40.7 40.4 40.4 40.4 3 33 34 34 34 34 34 33.5 33.5 33.5 33.5 5 29 30.8 30 30.1 30.1 30.1 30.1 30.1 29.6 29.7 8 19 19.3 19.3 19.3 19.3 19.3 19.3 19.2 19.2 19.2 10 17 17.8 17.4 17.3 17.3 17.3 17.3 17.3 17.2 17.2 15 9 11 11 10.8 10.6 10.6 10.6 10.6 10.6 10.6 20 4 5.5 5.4 5 5 5 5 5 5 5

Table 1 shows the experimental data for FIG. As shown in the table, various experiments were conducted over time. As a result of the experiment, it can be seen that the temperature of each part does not differ significantly with time.

9 shows an image of a temperature distribution of the surface of the electrostatic chuck that appears when the cooling water flow path is configured and tested. As shown in the figure, it can be seen that the temperature distribution on the surface of the electrostatic chuck is kept uniform.

In the above, the heat transfer gas supply flow path of the electrostatic chuck body, the heat transfer gas ejection structure of the ceramic sheet, and the cooling flow path structure inside the electrostatic chuck are described separately, but each of them may be independently applied to the electrostatic chuck, and two or more of them may be variously combined. Can be applied to the electrostatic chuck.

The following describes the processing operation using the plasma processing apparatus described above. When the substrate 110 is loaded from the substrate loading / unloading port 115 and mounted on the upper surfaces of the electrostatic chucks 118 and 119, the inside of the vacuum chamber 124 is reduced by the exhaust device 113. The high power source is applied to the electrostatic chucks 118 and 119 from the high voltage direct current power supply 130 so that the substrate 110 is adsorbed and held by the constant power. The heat transfer gas controlled at a predetermined temperature and flow rate from the heat transfer gas source 133 is then passed through the supply line 132 to the inner inlet 150 and the outer inlet 156 of the electrostatic chucks 118, 119 according to the invention. Supplied to the ceramic sheet 119 from the plurality of gas ejection holes 160 to the microcavities between the substrate 110 and the electrostatic chucks 118 and 119 so that the substrate 110 is uniformly adjusted to a desired temperature. do. In addition, the coolant flows from the chiller 128 outside the vacuum chamber 124 along the cooling passages of the electrostatic chucks 118 and 119 to cool the electrostatic chucks 118 and 119 and then discharges them. Thereafter, the plasma processing gas is introduced from the shower head installed in the upper electrode part 112, and the vacuum chamber 124 is maintained at a predetermined pressure by using the vacuum pump 124. The high frequency power matched from the outside is applied to the upper and lower electrode portions 112 and 114, the gas is ionized in the vacuum chamber 124 by the high frequency power, and the plasma in the space between the upper and lower electrode portions 112 and 114. Generates. By such a high-density plasma, plasma treatment such as dry etching is uniformly performed. When the plasma processing is completed, the power supply is stopped from the high-voltage DC power supply and the high frequency power supply 130 and 122, and the substrate 110 is carried out to the outside of the vacuum chamber 124 through the loading-out port 115.

As described above, the electrostatic chuck and the plasma processing apparatus according to the present invention implement various gas flow paths through which the heat transfer gas moves, and form a plurality of holes of various shapes on the surface of the ceramic sheet adhered to the electrostatic chuck, The cooling passage inside the chuck was rebuilt.

Therefore, since the present invention distributes and supplies the flow of the heat transfer gas appropriately, there is an effect that the heat transfer gas can be uniformly distributed on the back surface of the substrate and cooled uniformly from the center to the edge of the substrate.

In addition, the cooling efficiency can be improved by increasing the contact area of the cooling water through the improved cooling passage.

In addition, the present invention can be uniformly cooled even if the substrate is enlarged, thereby the semiconductor process such as etching, deposition, etc. can be uniformly carried out in the substrate.

Claims (17)

delete delete delete delete delete delete delete delete delete In the cooling flow path formed in the chuck supporting the substrate, A first opening formed at one edge of the inside of the chuck; A second opening formed at one side of the central region of the chuck; A spiral cooling passage connecting the first and second openings; The spiral cooling passage has a shape that rotates at least two rotations, wherein at least a portion of the spiral passage is formed with a projection. The method of claim 10. Wherein said first opening is an inlet and said second opening is an outlet. The cooling passage according to any one of claims 10 to 11, wherein a plurality of the protrusions are formed, and each of the protrusions includes a cylinder, an elliptic cylinder, and a polygonal column. The cooling passage according to any one of claims 10 to 11, wherein the protrusion includes one or more fence shapes formed along the cooling passage. The cooling channel of claim 13, wherein the fence has a corrugated shape. delete delete delete

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