JP6483533B2 - Sample holder and plasma etching apparatus using the same - Google Patents

Description

  The present invention relates to a sample holder for holding a semiconductor wafer or the like, for example, in a manufacturing process of a semiconductor integrated circuit, and a plasma etching apparatus using the same.

  A sample holder is known as a part for holding each sample such as a semiconductor wafer in a manufacturing process of a semiconductor integrated circuit or a manufacturing process of a liquid crystal display device. Examples of the sample holder include an electrostatic chuck described in Patent Document 1. The electrostatic chuck described in Patent Document 1 has a ceramic body having a sample holding surface on the upper surface and a recess on the lower surface, an electrostatic electrode embedded in the ceramic body, a via-hole conductor extending downward from the electrostatic electrode, And an electrode that is connected to the via-hole conductor and extends along the sample holding surface. The electrode is connected to the terminal inside the recess. In recent years, in order to reduce the warpage of the ceramic body due to the difference in thermal expansion between the electrode and the ceramic body under a heat cycle, it is required to make the electrode thinner.

JP 2006-287213 A

  However, in the electrostatic chuck described in Patent Document 1, it is difficult to thin the electrode while ensuring long-term reliability. Specifically, when the entire electrode is thinned, the durability of the electrode itself is lowered, and there is a possibility that a crack may occur at the connection portion between the via-hole conductor and the electrode. For this reason, there is a possibility that the reliability of connection between the via-hole conductor and the electrode is lowered.

  The present invention has been made in view of such problems, and an object of the present invention is to provide a sample holder capable of reducing warpage occurring in a ceramic body while ensuring connection reliability, and a plasma etching apparatus using the sample holder. It is to provide.

A sample holder according to an aspect of the present disclosure includes a ceramic body having a sample holding surface on an upper surface and a recess on a lower surface, and an electrostatic adsorption electrode that extends along the sample holding surface and is embedded in the ceramic body. A via hole conductor extending from the electrostatic attraction electrode to the lower surface side of the ceramic body, and connected to an end of the via hole conductor on the lower surface side of the ceramic body and provided in a direction along the sample holding surface , An electrode that is at least partially exposed to the recess, and a lead terminal that is inserted into the recess and connected to the electrode, the electrode being connected to the via-hole conductor rather than a portion connected to the lead terminal. towards the connecting portion is rather thick, the electrostatic attraction electrodes
The top surface of the substrate is characterized in that the portion directly above the portion to which the via-hole conductor is connected has a convex shape on the sample holding surface side .

  A plasma etching apparatus according to an aspect of the present invention includes a vacuum chamber, a base plate having a high-frequency application electrode disposed in the vacuum chamber, and the sample holder mounted on the base plate. To do.

According to the sample holder of one embodiment of the present invention, it is possible to reduce the warpage generated in the ceramic body while ensuring the reliability of connection.

  According to the plasma etching apparatus of one embodiment of the present invention, long-term reliability can be improved by including the sample holder.

It is sectional drawing which shows the sample holder of one Embodiment of this invention, and the plasma etching apparatus using the same. It is sectional drawing which shows the modification of the sample holder shown in FIG. It is sectional drawing which shows the modification of the sample holder shown in FIG. It is sectional drawing which shows the modification of the sample holder shown in FIG.

  Hereinafter, a sample holder 10 and a plasma etching apparatus 100 using the same according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view showing a sample holder 10 according to an embodiment of the present invention. As shown in FIG. 1, a sample holder 10 of the present embodiment includes a ceramic body 1 having a sample holding surface 11 on one main surface, and an electrostatic adsorption electrode 2 that is spread and embedded along the sample holding surface 11. A via hole conductor 4 connected to the electrostatic chucking electrode 2, an electrode 5 connected to the via hole conductor 4, and a lead terminal 9 connected to the electrode 5. The sample holder 10 further includes a heating resistor 3 provided on the other main surface of the ceramic body 1.

  The ceramic body 1 is a plate-like member having a sample holding surface 11 on one main surface (upper surface). The ceramic body 1 holds a sample such as a silicon wafer on a sample holding surface 11 on the upper surface. The ceramic body 1 is a member having a circular shape when viewed in plan. The ceramic body 1 is made of a ceramic material such as alumina, aluminum nitride, silicon nitride, or yttria. The dimensions of the ceramic body 1 can be set to a diameter of 200 to 500 mm and a thickness of 2 to 15 mm, for example. The sample holder 10 of this embodiment holds a sample by electrostatic force. Therefore, the sample holder 10 includes an electrostatic adsorption electrode 2 inside the ceramic body 1.

  The electrode 2 for electrostatic attraction is composed of two electrodes (only one electrode is shown in FIG. 1). One of the two electrodes is connected to the positive electrode of the power source, and the other is connected to the negative electrode. The two electrodes are each formed in a substantially semicircular shape, and are arranged inside the ceramic body 1 so that the semicircular strings face each other with a gap. The outer shape of the electrostatic attraction electrode 2 is circular due to the arc of these two electrodes. The center of the circular outer shape of the entire electrostatic adsorption electrode 2 is set to be the same as the center of the outer shape of the circular ceramic body 1. The electrostatic adsorption electrode 2 is made of a metal material such as tungsten or molybdenum.

  The via-hole conductor 4 extends from the electrostatic attraction electrode 2 to the lower surface side of the ceramic body 1. The via-hole conductor 4 is a member for supplying power to the electrostatic chucking electrode 2. For example, the via-hole conductor 4 has a cylindrical shape. The via-hole conductor 4 is made of a metal material such as tungsten or molybdenum, for example.

  The electrode 5 is connected to an end of the via-hole conductor 4 on the lower surface side of the ceramic body 1 and is provided in a direction along the sample holding surface 11. The electrode 5 is a member for supplying power to the electrostatic attraction electrode 2 together with the via-hole conductor 4. The electrode 5 is made of a metal material such as tungsten or molybdenum.

Here, the ceramic body 1 has the recessed part 12 opened to a lower surface. A part of the electrode 5 is exposed on the bottom surface of the recess 12. More specifically, the recess 12 penetrates the electrode 5, and the electrode 5 is exposed on the wall surface of the recess 12. The recess 12 is provided for inserting the lead terminal 9. The shape of the recess 12 is, for example, a cylindrical shape. The size of the recess 12 is determined in accordance with the size of the lead terminal 9 to be inserted. Specifically, the dimension of the recess 12 is set so as to form a gap that allows the lead terminal 9 to be easily inserted between the outer peripheral surface of the lead terminal 9 and the inner peripheral surface of the recess 12. When the lead terminal 9 has a cylindrical shape with an outer diameter of 1.5 mm, the diameter of the recess 12 can be set to 2 to 10 mm.

  The lead terminal 9 is a member for electrically connecting an external power source (not shown) and the electrode 5 and supplying electric power to the electrostatic chucking electrode 2. The lead terminal 9 is a cylindrical member, for example, and is used by being inserted into the recess 12. The lead terminal 9 is connected to the electrode 5 inside the recess 12. Specifically, the lead terminal 9 exposed on the wall surface of the recess 12 and the electrode 5 are connected by a conductive bonding material 13. As the bonding material 13, for example, a conductive resin can be used.

  The heating resistor 3 is a member for heating the sample held on the sample holding surface 11 on the upper surface of the ceramic body 1. The heating resistor 3 is provided on the other main surface (lower surface) of the ceramic body 1. By applying a voltage to the heating resistor 3, the heating resistor 3 can be heated. The heat generated by the heating resistor 3 is transmitted through the ceramic body 1 and reaches the sample holding surface 11 on the upper surface of the ceramic body 1. Thereby, the sample held on the sample holding surface 11 can be heated. The heating resistor 3 is, for example, a linear pattern having a plurality of curved portions, and is formed on almost the entire lower surface of the ceramic body 1. Thereby, it can suppress that dispersion | variation arises in heat distribution in the upper surface of the sample holder 10. FIG.

  The heating resistor 3 includes a conductor component and a glass component. As a conductor component, metal materials, such as silver palladium, platinum, aluminum, or gold | metal | money, are contained, for example. As the glass component, glass containing oxides of materials such as silicon, aluminum, bismuth, calcium, boron and zinc can be used. For example, the thickness of the heating resistor 3 can be set to 20 to 70 μm.

  Here, in the sample holder 10 of the present embodiment, the portion of the electrode 5 connected to the via-hole conductor 4 is thicker than the portion connected to the lead terminal 9. Thus, by increasing the thickness of the portion connected to the via-hole conductor 4 rather than the portion connected to the lead terminal 9, the physical strength of the thickened portion of the electrode 5 can be improved. Therefore, it is possible to reduce the risk of cracks occurring between the electrode 5 and the via-hole conductor 4. Moreover, since the thermal stress generated between the lead body 9 and the ceramic body 1 can be reduced by thinning the portion connected to the lead terminal 9, the warp generated in the ceramic body 1 can be reduced. More specifically, the thickness of the portion of the electrode 5 located immediately below the via-hole conductor 4 can be set to, for example, 2 to 3.5 times the thickness of the portion connected to the lead terminal 9. Further, the region where the thickness is increased can be set in a range surrounded by a circle having a diameter of, for example, 1 to 3 times the diameter of the via-hole conductor 4 with the center just below the via-hole conductor 4.

  The electrode 5 may gradually increase in thickness from a portion connected to the lead terminal 9 to a portion connected to the via-hole conductor 4. Thereby, the thickness of the electrode 5 can be changed gradually. Therefore, the possibility that the thermal stress is partially concentrated on the electrode 5 can be reduced. For example, the portion of the electrode 5 connected to the via-hole conductor 4 may be dome-shaped as the structure gradually increases from the portion connected to the lead terminal 9 to the portion connected to the via-hole conductor 4. . Such a configuration can be formed by, for example, a screen printing method. Specifically, when the paste-like electrode 5 material is laminated, the number of laminated layers in the portion that will be located immediately below the via hole may be increased.

  Here, “becomes thicker” means both a case where the thickness is increased smoothly and a case where the thickness is increased stepwise. As a case where the thickness is smoothly increased, for example, as shown in FIG. 4, there is a case where the entire electrode 5 has a dome shape. Moreover, as a case where it becomes thick gradually, the case where the surface of the electrode 5 is step shape is mentioned, for example.

  In addition, as shown in FIG. 2, the upper surface of the electrostatic attraction electrode 2 may have a convex shape on the sample holding surface 11 side immediately above the portion to which the via-hole conductor 4 is connected. Generally, the temperature directly below the portion of the sample holding surface 11 where the via-hole conductor 4 is provided is lower than the surroundings. This is because heat escapes to the outside through the via-hole conductor 4. Therefore, there is a possibility that the soaking property in the sample is lowered. Therefore, by making the upper surface of the upper surface of the electrostatic chucking electrode 2 directly above the portion to which the via-hole conductor 4 is connected, the portion immediately above the portion to which the via-hole conductor 4 is connected can be brought closer to the sample holding surface 11. (The sample held on the sample holding surface 11 can be brought close to the portion directly connected to the via hole conductor 4). When the sample is held using Coulomb force, the electrostatic adsorption force is inversely proportional to the square of the distance. Therefore, the electrostatic attraction force directly above the via-hole conductor 4 can be increased by bringing the portion directly above the portion to which the via-hole conductor 4 is connected closer to the sample holding surface 11. Thereby, heat can be easily transferred to the sample immediately above the via-hole conductor 4. As a result, the heat uniformity of the sample can be improved. The upper surface of the convex portion of the electrostatic attraction electrode 2 protrudes, for example, by 15 to 35 μm compared to the surroundings. Such a configuration can be formed by, for example, a screen printing method. Specifically, it is only necessary to increase the number of stacked layers in the portion of the upper surface of the electrostatic chucking electrode 2 that is located immediately above the via hole.

  Further, as shown in FIG. 3, the via-hole conductor 4 is thin in a portion connected to the electrostatic attraction electrode 2 and a portion connected to the electrode 5. Specifically, the via-hole conductor 4 has a barrel shape, for example. Thereby, the thermal stress generated in the via-hole conductor 4 can be released in various directions. As a result, the durability of the sample holder 10 can be improved. In such a configuration, for example, when a ceramic body 1 is formed by laminating a plurality of ceramic green sheets, holes are made in advance in the ceramic green sheets, and the ceramic green sheets are laminated so that the holes overlap. At this time, when the ceramic green sheets are laminated, a hole is made in each ceramic green sheet so that the shape in which the plurality of holes are combined becomes a barrel shape. And the shape of the via-hole conductor 4 can be made into a barrel shape by pouring the electroconductive paste used as the via-hole conductor 4 with respect to a hole.

  Returning to FIG. 1, a part of the plasma etching apparatus 100 using the above-described sample holder 10 will be described. The plasma etching apparatus 100 includes a vacuum chamber (not shown), a base plate 6 having a high-frequency application electrode 5 (not shown) disposed in the vacuum chamber, and a sample holder 10 mounted on the base plate 6. I have.

  The base plate 6 is a plate-like member that incorporates therein a flow path for a cooling medium (not shown) and a flow path for flowing a heat transfer gas such as helium or argon on the upper surface of the sample holder 10. As the base plate 6, for example, a metal material such as aluminum or titanium, a ceramic material such as silicon carbide, or a composite material of silicon carbide and aluminum can be used.

  The heating resistor 3 of the sample holder 10 is covered with an insulating layer 7. As the insulating layer 7, an adhesive material or ceramic material containing a ceramic filler is used. The insulating layer 7 is bonded to the upper surface of the base plate 6 with a resin layer 8.

  As the resin layer 8, an adhesive resin can be used. Specifically, a silicone resin, an epoxy resin, an acrylic resin, or the like can be used. The resin layer 8 may contain a filler. By containing the filler, the thermal conductivity of the resin layer 8 can be improved. Any filler may be used as long as it has higher thermal conductivity than a resin material such as a ceramic material or a metal material. Specifically, when the filler is made of a metal, for example, a filler made of aluminum can be used. When the filler is made of a ceramic material, alumina, silicon carbide, aluminum nitride, or silicon nitride can be used.

  The resin layer 8, the insulating layer 7, and the base plate 6 are provided with through holes that connect to the recesses 12 so that the lead terminals 9 can be inserted into the recesses 12 of the ceramic body 1. Thereby, even when the resin layer 8, the insulating layer 7, and the base plate 6 are provided on the lower surface of the ceramic body 1, the lead terminal 9 can be inserted into the recess 12 from the lower surface of the ceramic body 1.

  The plasma etching apparatus 100 can improve long-term reliability by including the sample holder 10 described above.

1: Ceramic body 11: Sample holding surface 12: Recess 2: Electrode for electrostatic adsorption 3: Heating resistor 4: Via hole conductor 5: Electrode 6: Base plate 7: Insulating layer 8: Resin layer 9: Lead terminal 10: Sample holding Tool 100: Plasma etching apparatus

Claims (4)

A ceramic body having a sample holding surface on the upper surface and a recess on the lower surface, an electrode for electrostatic attraction extending along the sample holding surface and embedded in the ceramic body, and the ceramic body from the electrode for electrostatic attraction A via hole conductor extending to the lower surface side of the electrode, an electrode connected to the lower surface side end of the ceramic body of the via hole conductor and provided in a direction along the sample holding surface, and at least a part of the electrode exposed to the recess , is inserted into the recess and a lead terminal connected to the electrode, the electrode, the rather thick towards a portion connected to the via hole conductors than the connected portions to the lead terminal, the A sample holder, wherein the upper surface of the electrostatic adsorption electrode has a convex shape directly above the portion to which the via-hole conductor is connected . The sample holder according to claim 1, wherein the via-hole conductor is thin at a portion connected to the electrode for electrostatic adsorption and a portion connected to the electrode. The sample holder according to claim 1 or 2 , wherein the electrode is gradually thickened from a portion connected to the lead terminal to a portion connected to the via-hole conductor. The plasma etching apparatus provided with the vacuum chamber, the base plate which has the electrode for high frequency application arrange | positioned in this vacuum chamber, and the sample holder in any one of Claim 1 thru | or 3 mounted in this base plate .

Images