KR20080076432A - Plasma processing appratus - Google Patents

Abstract

A plasma processing apparatus is provided to minimize a flatness change of a cooling plate by efficiently controlling a heat transfer between a silicon electrode and a cooling plate. A plasma processing apparatus includes a chamber(100), an electrostatic chuck(110), a silicon electrode(120), and a cooling plate(140). The electrostatic chuck is installed inside the chamber. A substrate is installed on an upper plane of the electrostatic chuck. The silicon electrode is installed on an upper part of the electrostatic chuck to be apart from the electrostatic chuck. A plurality of grooves are formed on the upper plane of the silicon electrode. The cooling plate is contacted with an upper plane except the groove of the silicon electrode, and emits a heat of the silicon electrode. The silicon electrode is a cathode of the plasma processing apparatus. The electrostatic chuck is an anode of the plasma processing apparatus.

Description

Plasma processing appratus

1 is a schematic cross-sectional view showing a plasma processing apparatus including a cathode according to an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view of a cathode of the plasma processing apparatus of FIG. 1.

3 is a perspective view illustrating the silicon electrode of FIG. 2.

4 is a partially enlarged cross-sectional view of a cathode of the plasma processing apparatus according to another embodiment of the present invention.

5 is a perspective view illustrating the silicon electrode and the spacer of FIG. 4.

FIG. 6 is a graph showing the change in flatness of the cooling plate with respect to the passage of time while heating the silicon electrode before groove formation to 150 ° C.

7 is a graph showing a change in flatness of the cooling plate with respect to the passage of time during heating of the silicon electrode after groove formation to 150 ° C.

<Description of the symbols for the main parts of the drawings>

100: chamber 110: electrostatic chuck

120, 220: silicon electrodes 122, 124, 126: grooves

121, 221: Bolt ball 128, 228: First injection hole

148 and 248: second injection holes 130 and 230: bolts

140, 240: cold plate 222, 224, 226: spacer

The present invention relates to a plasma processing apparatus, and more particularly, to a plasma processing apparatus in which grooves or spacers are formed in a silicon electrode in contact with a cooling plate to control heat transfer between the silicon electrode and the cooling plate.

In general, a process of treating a substrate using plasma may include dry etching using plasma and thin film deposition using plasma. In addition, there are various methods such as reactive ion etching (RIE) or ion milling, which have been developed to overcome various limitations related to the chemical treatment method of semiconductor substrates.

As such, an apparatus for processing a substrate using plasma may be classified into a lower structure and an upper structure. For example, the substructure includes an electrostatic chuck that is a substrate seat and is located at the bottom within the device, and the superstructure is located at the top of the electrostatic chuck. The superstructure includes a silicon electrode, which is used by combining graphite and silicon with elastomer bonding.

However, in the case where the graphite electrode and the silicon are combined by the elastomer bonding as the silicon electrode, the elastomer may be melted by the plasma during the process, and particles are generated from the elastomer and the graphite to cause a process defect.

On the other hand, in the process of processing the substrate using the plasma, heat generated from the silicon electrode exposed to the plasma is released through the support plate attached to the upper portion of the silicon electrode. In this case, the support plate and the silicon electrode have different thermal expansion coefficients, and may have different directions in thermal expansion, and thus may be bent in opposite directions. In this case, the silicon electrode is broken, resulting in process defects.

SUMMARY OF THE INVENTION The present invention has been made in an effort to provide a plasma processing apparatus capable of minimizing change in flatness of a cooling plate and preventing breakage of the silicon electrode by controlling heat transfer between the silicon electrode and the cooling plate in the plasma processing apparatus. It is.

Technical problems of the present invention are not limited to the technical problems mentioned above, and other technical problems not mentioned will be clearly understood by those skilled in the art from the following description.

Plasma processing apparatus according to an embodiment of the present invention for achieving the above technical problem is a chamber, an electrostatic chuck installed in the chamber and the substrate is mounted on the upper surface, spaced apart from the electrostatic chuck on the top of the electrostatic chuck, the upper surface A silicon electrode in which a plurality of grooves are formed, and a cooling plate in contact with the upper surface of the silicon electrode, except for the groove, and discharges heat of the silicon electrode to the outside.

Plasma processing apparatus according to another embodiment of the present invention for achieving the technical problem is a chamber, an electrostatic chuck installed in the chamber and the substrate is mounted on the upper surface, a silicon electrode spaced apart from the electrostatic chuck on the top of the electrostatic chuck, A plurality of spacers located on the upper surface of the silicon electrode, and a cooling plate in contact with the upper surface of the spacer, and discharges the heat of the silicon electrode to the outside.

Specific details of other embodiments are included in the detailed description and drawings.

Advantages and features of the present invention, and methods for achieving them will be apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the present embodiments are intended to complete the disclosure of the present invention, and those skilled in the art to which the present invention pertains. It is provided to fully inform the scope of the invention, and the invention is defined only by the scope of the claims. In each of the drawings shown in the present invention, each component may be shown to be somewhat enlarged or reduced in view of the convenience of description. Like reference numerals refer to like elements throughout.

Hereinafter, a plasma processing apparatus according to an embodiment of the present invention will be described with reference to the accompanying drawings.

1 is a schematic cross-sectional view showing a plasma processing apparatus including a cathode according to an embodiment of the present invention.

Referring to FIG. 1, the plasma processing apparatus 10 includes a chamber 100, an electrostatic chuck 110, a silicon electrode 120, and a cooling plate 140.

The chamber 100 provides a space in which the substrate w is processed. The chamber 100 may be a vacuum chamber in which a vacuum is maintained. In such a chamber 100, dry etching using plasma or a thin film deposition process using plasma may be performed.

The electrostatic chuck 110 is positioned below the chamber 100, and the substrate w is mounted on the upper surface of the electrostatic chuck 110. The electrostatic chuck 110 is a mounting portion of the substrate w and an anode of the plasma processing apparatus 10. A high frequency power supply unit 117 may be installed below the electrostatic chuck 110 to supply high frequency power for forming plasma. In addition, the lower portion of the electrostatic chuck 110 may be provided with a cooling device 115 to adjust the temperature of the electrostatic chuck 110. As such, the contents of the electrostatic chuck 110, the cooling device 115 under the electrostatic chuck 110, and the high frequency power supply 117 are well known in the art, and the present invention is avoided from being obscured. The detailed description thereof will be omitted.

The silicon electrode 120 is spaced apart from the electrostatic chuck 110 on the electrostatic chuck 110. The silicon electrode 120 constitutes a cathode of the plasma processing apparatus 10 and may be made of a single silicon material. In addition, a plurality of grooves 122, 124, and 126 are formed on the upper surface of the silicon electrode 120. In this case, at least a portion of the grooves 122, 124, and 126 may be formed in a ring shape. For example, it may be a circular ring shape, but is not limited thereto. For example, the grooves 122, 124, and 126 may be formed in the shape of polygonal rings or plates. That is, various types of deformation grooves may be applied to partially contact the upper surface of the silicon electrode 120 and the lower surface of the cooling plate 140 to be described below. In addition, the silicon electrode 120 has a plurality of first injection holes 128 for injecting a reaction gas.

Next, the cooling plate 140 is positioned above the silicon electrode 120, and thermally stabilizes the silicon electrode 120. The cooling plate 140 may be made of, for example, anodized aluminum. In addition, the cooling plate 140 is in contact with the top surface of the silicon electrode 120 except for the space formed by the grooves 122, 124, and 126 formed on the top surface of the silicon electrode 120. At this time, the lower surface of the cooling plate 140 is in the form of a flat plate. Therefore, when the substrate w is processed using plasma, heat generated in the silicon electrode 120 may be transferred to the cooling plate 140 through a contact surface between the silicon electrode 120 and the cooling plate 140. On the other hand, the cooling plate 140 may be provided with a conduit (not shown) through which the refrigerant can be circulated. In this case, the refrigerant may be a gas or a liquid. The pipeline (not shown) of the refrigerant may be composed of, for example, one line or two or more lines. Here, the cooling plate 140 has a coolant inlet 147 on one side and a coolant outlet 149 on the other side. Although not shown in the drawing, the refrigerant circulates along a conduit (not shown) inside the cooling plate 140, absorbs heat transferred from the silicon electrode 120, and then is discharged through the outlet 149. In addition, a plurality of second injection holes 148 corresponding to the first injection holes 128 of the silicon electrode 120 are formed in the cooling plate 140. Therefore, the reaction gas supplied through the gas supply unit 145 may be injected through the first injection hole 128 and the second injection hole 148.

Next, referring to Figures 2 and 3, the plasma processing apparatus according to an embodiment of the present invention will be described in more detail.

FIG. 2 is a schematic cross-sectional view illustrating a cathode of the plasma processing apparatus of FIG. 1, and FIG. 3 is a perspective view illustrating the silicon electrode of FIG. 2.

2 and 3, the cathode 150 includes a silicon electrode 120 and a cooling plate 140.

The silicon electrode 120 includes a plurality of first injection holes 128 for injecting a reaction gas. The first injection holes 128 may be formed at uniform intervals from the center of the silicon electrode 120 to the edge portion. For example, the first injection hole 128 may be formed in a radial structure or a tiled structure around a central portion of the silicon electrode. For example, ring-shaped grooves 122, 124, and 126 may be formed on the top surface of the silicon electrode 120, and the silicon electrodes 120 recessed by the grooves 122, 124, and 126, respectively. The first injection hole 128 may be formed at even intervals on the upper surface of the first injection hole 128. At this time, the first injection hole 128 is formed to penetrate the silicon electrode 120 for the injection of the reaction gas. On the other hand, a plurality of bolt holes 121 are formed in the upper portion of the silicon electrode 120 in contact with the cooling plate 140. Here, unlike the first injection hole 128, the bolt hole 121 is not formed to penetrate the silicon electrode 120 but is formed only at a predetermined depth. In addition, the silicon electrode 120 and the cooling plate 140 are coupled by a plurality of bolts 130.

The cooling plate 140 includes a plurality of second injection holes 148 corresponding to the plurality of first injection holes 128 formed in the silicon electrode 120. At this time, the plurality of second injection holes 148 are formed so as not to overlap with the pipeline (not shown) of the refrigerant disposed in the cooling plate 140. That is, a pipeline (not shown) of the refrigerant may be disposed between the plurality of second injection holes 148 formed at regular intervals, and does not affect the injection of the reaction gas. Then, the reaction gas injected into the chamber 100 is injected through the second injection hole 148 of the cooling plate 140 and the first injection hole 128 of the silicon electrode 120 in order, and then electrostatic chuck In the space between the 110 and the silicon electrode 120 may be plasma by the high frequency power supplied from the high frequency power supply 117. Meanwhile, although the first and second injection holes 128 and 148 are slightly enlarged in size and reduced in number for convenience of description in FIG. 2, the first injection holes 128 are divided into a plurality as shown in FIG. 3. The second injection hole 148 may be formed to correspond to the first injection hole 128.

Hereinafter, a method of controlling heat transferred between the silicon electrode 120 and the cooling plate 140 in the plasma processing apparatus 10 as described above will be described in detail.

As described above, the silicon electrode 120 is directly exposed to the plasma when the substrate w is processed using the plasma. In this case, high temperature heat is transferred to the silicon electrode 120, and the heat is transferred to the cooling plate 140 coupled to the upper portion of the silicon electrode 120. For example, when the cooling plate 140 is made of anodized aluminum, the cooling plate 140 has a larger coefficient of thermal expansion than the silicon electrode 120. Therefore, when heat is transferred from the silicon electrode 120 and the cooling plate 140 to the cooling plate 140, the degree and direction of bending may be different due to different thermal expansion rates. For example, the cooling plate 140 may be bent in a convex shape, and the silicon electrode 120 may be bent in a convex shape. Of course, the reverse may also be included.

At this time, by forming a plurality of grooves 122, 124, and 126 on the upper surface of the silicon electrode 120, heat transmitted from the silicon electrode 120 to the cooling plate 140 may be controlled. For example, the contact area between the silicon electrode 120 and the cooling plate 140 may be adjusted by adjusting the size, position, occupation area, or shape of the grooves 122, 124, and 126 formed on the upper surface of the silicon electrode 120. By adjusting, the heat transferred from the silicon electrode 120 to the cooling plate 140 can be controlled. Of course, while controlling the contact area between the silicon electrode 120 and the cooling plate 140, sufficient heat is transferred from the silicon electrode 120 to the cooling plate 140. That is, the grooves 122, 124, and 126 formed on the upper surface of the silicon electrode 120 adjust the heat transmitted between the silicon electrode 120 and the cooling plate 140 to adjust the degree of bending of the cooling plate 140. It can play a role in controlling. In other words, the grooves 122, 124, and 126 may control the heat transferred between the silicon electrode 120 and the cooling plate 140 to reduce the flatness change of the cooling plate 140. Therefore, the silicon electrode 120 and the cooling plate 140 may be bent in different directions, or the breakage of the silicon electrode 120 may be prevented due to a different degree of bending.

4 is a partially enlarged cross-sectional view of a cathode of the plasma processing apparatus according to another embodiment of the present invention, and FIG. 5 is a perspective view illustrating the silicon electrode and the spacer of FIG. 4. In the present embodiment, the same components as in the embodiments of FIGS. 1 to 3 will be omitted or simplified, and will be described based on differences.

 4 and 5, the cathode 250 includes a silicon electrode 220, spacers 222, 224, and 226, and a cooling plate 240. The silicon electrode 220 according to the present exemplary embodiment is different from the silicon electrode 120 described with reference to FIGS. 1 to 3 in that the upper surface thereof is flat. That is, there is no groove on the top surface of the silicon electrode 220 according to the present embodiment, and the silicon electrode 220 includes a plurality of first injection holes 228 and bolt holes 221.

The plurality of spacers 222, 224, and 226 are positioned on the top surface of the silicon electrode 220. The spacers 222, 224, and 226 include a plurality of injection holes 223 and bolt holes 225 corresponding to the first injection holes 228 and the bolt holes 221 of the silicon electrode 220. At least some of the spacers 222, 224, and 226 may be formed in a ring shape. For example, it may be formed in a circular ring shape, but is not limited thereto. For example, the spacers 222, 224, and 226 may be formed in the shape of polygonal rings or plates.

The cooling plate 240 is positioned above the spacers 222, 224, and 226. At this time, the lower surface of the cooling plate 240 in contact with the upper surface of the spacer 222, 224, 226 is in the form of a flat plate. In addition, the cooling plate 240 includes a plurality of second injection holes 248 corresponding to the first injection holes 228 of the silicon electrode 220. Here, although the first and second injection holes 228 and 248 are slightly enlarged in size and reduced in number for convenience of description in FIG. 4, the first injection holes 228 are divided into a plurality as shown in FIG. 5. The second injection hole 248 may be formed to correspond to the first injection hole 228. On the other hand, since the structure of the cooling plate 240 is substantially the same as the structure of the cooling plate 140 described in an embodiment of the present invention will not be repeated description.

As described above, the silicon electrode 220, the spacers 222, 224, and 226 and the cooling plate 240 are coupled to the bolt 230. In this case, the respective injection holes 223, 228, and 248 are also aligned, and the reaction gas passes through the silicon electrode 220 from the cooling plate 240 through the spacers 222, 224, and 226, and thus, of the silicon electrode 220. Of course it can be plasma at the bottom.

Also in the plasma processing apparatus including the cathode 250 having such a structure, the silicon electrode 220 is exposed to the plasma when the substrate w is processed using the plasma. Therefore, high temperature heat is transferred to the silicon electrode 220, and heat is transferred to the cooling plate 240 through the spacers 222, 224, and 226 on the silicon electrode 220. In this case, the spacers 222, 224, and 226 may be formed of, for example, a material such as the silicon electrode 220 or a material such as the cooling plate 240 in order to effectively transfer heat from the silicon electrode 220 to the cooling plate 240. It can be formed as. However, the material of the spacers 222, 224, and 226 is not limited thereto. For example, the spacers 222, 224, and 226 may have various thermal materials having excellent thermal conductivity while having a thermal expansion coefficient between the silicon electrode 220 and the cooling plate 240.

Meanwhile, heat transferred from the silicon electrode 220 to the cooling plate 240 may be controlled through the spacers 222, 224, and 226. For example, the contact area of the silicon electrode 220 and the cooling plate 240 through the spacers 222, 224, 226 may be adjusted according to the size, position, occupancy area, or shape of the spacers 222, 224, 226. Accordingly, heat transmitted from the silicon electrode 220 to the cooling plate 240 through the spacers 222, 224, and 226 may be adjusted. Therefore, according to the present embodiment, it is possible to reduce the change in the flatness of the cooling plate 240 and to prevent the breakage of the silicon electrode 220.

More detailed information about the present invention will be described through the following specific experimental examples, and details not described herein will be omitted because it is sufficiently technically inferred by those skilled in the art.

Experimental Example

In the case where no groove was formed on the upper surface of the silicon electrode and when the groove was formed, the flatness change of the cooling plate according to the heating of the silicon electrode was investigated. FIG. 6 is a graph showing a change in the flatness of the cooling plate with respect to the elapse of time during heating the silicon electrode before groove formation to 150 ° C, and FIG. 7 is a time elapsed while heating the silicon electrode after groove formation to 150 ° C. It is a graph showing the change in flatness of the cooling plate.

6 and 7, when grooves are formed on the upper surface of the silicon electrode in contact with the lower surface of the cooling plate, and the silicon electrode and the cooling plate are partially contacted, the change in the flatness of the cooling plate is significantly reduced. Able to know. That is, when no groove is formed on the upper surface of the silicon electrode, the cooling plate is bent to about 0.15 mm in whole or locally based on the initial state. On the other hand, in the case where a plurality of grooves were formed on the upper surface of the silicon electrode, the cooling plate was less than about 0.02 mm based on the initial state, and was only slightly bent as compared to the case where no groove was formed on the upper surface of the silicon electrode. . Therefore, it can be seen that by forming a groove on the upper surface of the silicon electrode it is possible to significantly reduce the flatness change of the cooling plate. Similarly, the same effect can be obtained even when a spacer is interposed between the silicon electrode and the cooling plate.

Therefore, by forming a groove on the upper surface of the silicon electrode, or by interposing a spacer between the silicon electrode and the cooling plate, it is possible to control the heat transfer between the silicon electrode and the cooling plate to minimize the flatness change of the cooling plate, accordingly It can be seen that it is possible to prevent breakage of the silicon electrode, which may occur due to the bending of the cooling plate.

Although embodiments of the present invention have been described above with reference to the accompanying drawings, those skilled in the art to which the present invention pertains may implement the present invention in other specific forms without changing the technical spirit or essential features thereof. I can understand that. Therefore, it should be understood that the embodiments described above are exemplary in all respects and not restrictive.

According to the plasma processing apparatus according to the embodiments of the present invention, by forming a groove on the upper surface of the silicon electrode by bonding a cooling plate, or by interposing a spacer between the silicon electrode and the cooling plate, to prevent process defects caused by particles. In addition, it is possible to effectively control the heat transfer between the silicon electrode and the cooling plate to minimize the flatness change of the cooling plate. Therefore, during the plasma treatment process, the silicon electrode is prevented from being overheated, and at the same time, the breakage of the silicon electrode, which may be caused by a difference in thermal expansion rate between the silicon electrode and the cooling plate, or by having different directions in thermal expansion, is effectively prevented. You can prevent it. Furthermore, process efficiency can be increased and the yield of a semiconductor wafer can be improved.

Claims (7)

chamber; An electrostatic chuck installed in the chamber and having a substrate mounted thereon; A silicon electrode spaced apart from the electrostatic chuck on the top of the electrostatic chuck and having a plurality of grooves formed on an upper surface thereof; And And a cooling plate in contact with an upper surface of the silicon electrode except for the groove and dissipating heat of the silicon electrode to the outside. According to claim 1, The silicon electrode is a cathode of the plasma processing apparatus, and the electrostatic chuck is an anode of the plasma processing apparatus. According to claim 1, At least a portion of the groove is formed in a ring shape. According to claim 1, And the cooling plate and the silicon electrode are coupled by a plurality of bolts. According to claim 1, The silicon electrode may include a plurality of first injection holes for injecting a reaction gas, and the cooling plate may include a plurality of second injection holes corresponding to the first injection holes. chamber; An electrostatic chuck installed in the chamber and having a substrate mounted thereon; A silicon electrode spaced apart from the electrostatic chuck above the electrostatic chuck; A plurality of spacers positioned on an upper surface of the silicon electrode; And And a cooling plate in contact with an upper surface of the spacer and dissipating heat from the silicon electrode to the outside. The method of claim 6, At least a portion of the spacer is a plasma processing apparatus consisting of a ring shape.

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