JP2007019190A - Supporting device and method of manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To allow using a wafer supporting device such as an electrostatic chuck which has an insulating layer consisting mainly of PBN on a base, under the condition of halogen atmosphere or even corrosion atmosphere, such as halogen plasma atmosphere. <P>SOLUTION: The wafer support device includes a corrosion-resistant protective film for coating an insulating layer substantially. The device is characterized in that the protective film has the compression stress of ≤280 MPa, more preferably of ≤250 Mpa. Such a protective film can be formed without causing the generation of a crack or exfoliation on the insulating layer, by a reactive ion plating method where Ar flow rate is set to ≤5 sccm, more preferably set to 0 sccm. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an apparatus used at a high temperature in a corrosive atmosphere such as ammonia, hydrogen, and halogen. For example, the present invention relates to a substrate, a liner, an evaporator, an evaporation apparatus, a heating element, a wafer support apparatus, an electrostatic chuck, a susceptor and other apparatuses. In one embodiment, this apparatus is particularly suitable for supporting a substrate such as a wafer having an insulating layer mainly composed of PBN (pyrolytic boron nitride) or in a wafer processing process such as semiconductor, glass, sapphire, and ceramic. It is used as a wafer support device that is suitably used as a chuck, a heater or the like. In another embodiment, the apparatus is based on PG (pyrolytic graphite). In the third embodiment, this apparatus uses a PBN or PG compound as a substrate. The invention also relates to a method for manufacturing such a device.

As an example, such an apparatus is used as a wafer support apparatus such as an electrostatic chuck for fixing a wafer in a wafer processing process such as semiconductor, glass, sapphire, and ceramic. An electrostatic chuck is formed by providing an electrostatic chuck electrode on the surface of an insulating base material and, if necessary, a heater electrode on the back surface thereof and covering them with an insulating layer such as PBN. Since there is no corrosion resistance against gas or halogen plasma, in Patent Document 1 below, an electrostatic chuck is formed by a film formation method such as sputtering, vapor deposition, ion plating, or CVD using aluminum nitride or aluminum oxynitride. It has been proposed to form a protective film having corrosion resistance against halogen gas or halogen plasma on the surface.
Japanese Patent Application Laid-Open No. 06-061335

  However, even if an attempt is made to form a corrosion-resistant protective film such as aluminum nitride or aluminum oxynitride by the conventional film forming method as shown in Patent Document 1, cracks and peeling occur and the film functions as a corrosion-resistant protective film. It was practically very difficult to carry out the coating. As a result of investigating the cause, PBN is a material having a low expansion coefficient. Therefore, the protective film formed at a high temperature is brought to room temperature due to a difference in thermal expansion coefficient between the protective film forming material such as aluminum nitride and aluminum oxynitride. It was found that strong tensile stress remained when cooled, resulting in cracks and peeling in the protective film.

  Therefore, the problem to be solved by the present invention is that a support device such as an electrostatic chuck having an insulating layer formed mainly of PBN on a substrate can be used in a corrosive atmosphere such as a halogen atmosphere or a halogen plasma atmosphere. It is to do.

  As a means for solving this problem, the present invention according to claim 1 is an apparatus used in a corrosive environment, in which an insulating layer mainly composed of PBN, PG, or a compound thereof is coated on a base material. The support device is characterized in that a corrosion-resistant protective film that substantially covers the insulating layer is formed, and the protective film has a compressive stress of 280 MPa or less.

  According to a second aspect of the present invention, in the apparatus of the first aspect, the protective film has a compressive stress of 250 MPa or less.

  According to a third aspect of the present invention, in the apparatus of the first or second aspect, the protective film is made of aluminum nitride or aluminum oxynitride.

  According to a fourth aspect of the present invention, there is provided a method for manufacturing the apparatus according to the first to third aspects, wherein an insulating layer mainly composed of PBN, PG, or a compound thereof is formed on a substrate, and then the insulating layer is formed. Further, a protective film is formed by a reactive ion plating method.

  The present invention according to claim 5 is characterized in that, in the manufacturing method according to claim 4, the Ar flow rate is 5 sccm or less in the formation of the protective film by the reactive ion plating method.

  The wafer support apparatus of the present invention has an insulating layer formed mainly of PBN, but has a corrosion-resistant protective film made of aluminum nitride, aluminum oxynitride or the like showing corrosion resistance against halogen gas or halogen plasma on the insulating layer. Therefore, it can be used in a corrosive atmosphere such as a halogen atmosphere or a halogen plasma atmosphere. The corrosion-resistant protective film has a corrosion resistance exhibited by an etch rate of less than 100 liters / minute in one embodiment, and has a corrosion resistance exhibited by an etch rate of less than 50 liters / minute in another embodiment. In form, it has corrosion resistance exhibited by an etch rate of less than 5 liters / minute.

  Further, according to the method for manufacturing a wafer support device of the present invention, when manufacturing the wafer support device having the above-described configuration, the reactive ion plating method is adopted and the Ar flow rate is controlled, so that PBN or PG can be obtained. A corrosion-resistant protective film free from cracks or peeling can be formed on the main insulating layer or substrate. Here, that no crack is generated means that no crack is observed with an optical microscope or an electron microscope with a magnification of 10K. The crack includes holes, perforations, fine holes, linear holes, and the like. In addition, the fact that peeling does not occur here means that the bonding strength of the protective film to the insulating layer (or base material) is higher than the film strength of the insulating layer itself below.

  Referring to FIG. 1, a 300 μm PBN insulating layer 2 is formed on the surface of a disk-shaped graphite plate 1 having a thickness of 10 mm by a thermal CVD method, and then a 50 μm PG layer is formed on both surfaces by the same thermal CVD method. After that, the front side PG layer to be the electrostatic chuck attracting surface is partially removed to form a chuck electrode 3 having a predetermined pattern, and the back side PG layer is also partially removed to have a predetermined heat pattern. Electrode 4 was provided to obtain electrostatic chuck heater substrate 5.

Next, the substrate 5 is reacted in a thermal CVD furnace with 3 mol of ammonia and 2.4 mol of methane gas at 0.5 Torr and a temperature of 1850 ° C. with respect to 1 mol of boron trichloride. An insulating layer 6 of 100 μm carbon-added PBN was formed. The insulating layer had an electrical resistivity of 2.8 × 10 ¹² Ω-cm, and exhibited a good electrostatic attraction force.

  Further, in order to make this electrostatic chuck heater usable in a corrosive atmosphere such as a halogen atmosphere or a halogen plasma atmosphere, while changing the Ar flow rate in the reactive ion plating method (0 sccm (= No Ar), 5 sccm, 10 sccm) And 15 sccm) by reacting nitrogen and aluminum at about 400 ° C., an AlN protective film 7 was formed as a protective film having corrosion resistance against halogen gas and halogen plasma, and an electrostatic chuck heater 8 was obtained. Further, an AlN film was formed by thermal CVD at 950 ° C. to obtain an electrostatic chuck heater of a comparative example.

  FIG. 2A is a surface SEM (scanning electron microscope) image of the AlN protective film formed by the comparative example, and FIG. 2B is an AlN film formed by reactive ion plating with an Ar flow rate of 15 sccm. FIG. 2C is a surface SEM (scanning electron microscope) image of the AlN protective film formed by the reactive ion plating method without flowing Ar. is there.

  In FIG. 2 (a), cracks have occurred, and it has been confirmed that AlN film formation by thermal CVD cannot be put to practical use.

  On the other hand, when the AlN film was formed by the reactive ion plating method, the AlN protective film 7 without cracks or peeling was formed in FIG. 2C where the Ar flow rate was zero, but the Ar flow rate was 15 sccm. In FIG. 2B, no crack was observed, but peeling occurred on the entire film. Although not shown, in the reactive ion plating method, when the Ar flow rate is 10 sccm, peeling occurs over the entire protective film in the same manner as in FIG. 2B, and when the Ar flow rate is 5 sccm. Although a part of the protective film peeled off, it was expected to exhibit a certain degree of corrosion resistance against halogen gas or halogen plasma.

  In addition, when the AlN protective film 7 having a thickness of 0.5 μm is formed on Si (100), the stress is measured by a deflection method with a Young's modulus of 130 GPa and a Poisson's ratio of 0.28, and the Ar flow rate is 0 sccm. The compression stress was 248 MPa when the Ar flow rate was 5 sccm, 267 MPa when the Ar flow rate was 10 sccm, 344 MPa when the Ar flow rate was 15 sccm, and 360 MPa when the Ar flow rate was 15 sccm. These relationships are shown in FIG. In addition, since the AlN protective film formed by the thermal CVD method was cracked in all the samples as shown in FIG. 2A, the stress could not be measured.

  From these results, in order to form the AlN film 7 as the halogen corrosion-resistant protective film on the insulating layer 6 mainly composed of PBN without causing cracks or peeling, a reactive ion plating method is adopted and It has been confirmed that it is necessary to form an AlN film 7 having a compressive stress of 280 MPa or less, preferably 250 MPa or less, with an Ar flow rate of 6 sccm or less, preferably 0 sccm.

  In the case of AlN film formation by thermal CVD, the crack occurred because the linear thermal expansion coefficient of PBN is smaller than that of a material such as aluminum nitride or aluminum oxynitride used as a protective film, so that film formation is performed at a high temperature. According to thermal CVD, a strong tensile stress remains in the protective film due to the difference in thermal expansion coefficient, and this tensile stress is assumed to cause cracks in the protective film (see FIG. 4A). On the other hand, when the reactive ion plating method is used, since an AlN film having a compressive stress is formed as shown in FIG. 3, no cracks are generated due to the destruction of the protective film (FIG. 4B). reference).

  In order to confirm the halogen corrosion resistance of the AlN protective film 7 formed by the reactive ion plating method in which the Ar flow rate is zero, an etching test is performed in an NF3 plasma atmosphere, and for comparison, a PBN film, a silicon wafer, and An etching test was performed on the sintered AlN film under the same conditions. As is apparent from FIG. 5 showing this result, when the PBN film is exposed without forming the protective film, the etching rate is extremely high at 10,000 Å / min, while by forming the AlN protective film. The etching rate is greatly reduced, and the etching rate of the AlN film formed by the reactive ion plating method is 4.8 Å / min compared to the etching rate (33 Å / min) of the AlN film formed by sintering. It was confirmed that the etching resistance was extremely high and the etching resistance was extremely high.

It is a schematic block diagram of the electrostatic chuck heater by one Embodiment of this invention. AlN protective film (a) formed by thermal CVD method, AlN protective film (b) formed by reactive ion plating method with Ar flow rate of 15 sccm, and ArN protective film formed by reactive ion plating method with Ar flow rate of 0 sccm It is each surface SEM image of the prepared AlN protective film (c). It is explanatory drawing which shows each behavior when a protective film has a tensile stress (a), and when it has a compressive stress (b). It is a figure which shows the dependence relationship between the Ar flow volume in the reactive ion plating method, and the compressive stress of the formed AlN protective film. It is a figure which shows the etching tolerance of the AlN protective film formed into a film by the reactive ion plating method by this invention compared with a PBN film | membrane and a sintered AlN film | membrane.

Explanation of symbols

1 Graphite plate 2 PBN insulating layer 3 Chuck electrode 4 Heater electrode 5 Electrostatic chuck heater substrate 6 Insulating layer 7 AlN protective film (halogen corrosion-resistant protective film)
8 Electrostatic chuck heater

Claims (5)

In an apparatus used in a corrosive environment, an insulating layer mainly composed of PBN, PG, or a compound thereof is formed on a base material, and a corrosion-resistant protective film that substantially covers the insulating layer is formed. A support device, wherein the membrane has a compressive stress of 280 MPa or less. The apparatus according to claim 1, wherein the protective film has a compressive stress of 250 MPa or less. 3. The apparatus according to claim 1, wherein the protective film is made of aluminum nitride or aluminum oxynitride. 4. A method of manufacturing an apparatus according to claim 1, wherein an insulating layer mainly composed of PBN, PG or a compound thereof is formed on a substrate, and then a reactive ion plating method is formed on the insulating layer. The manufacturing method characterized by forming a protective film by this. 5. The method according to claim 4, wherein the Ar flow rate is 5 sccm or less in the formation of the protective film by the reactive ion plating method.

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