TW201532112A - Plasma processing apparatus, electrostatic chuck, and method of manufacturing electrostatic chuck - Google Patents

Abstract

The present invention discloses an electrostatic chuck, its manufacturing method, and a plasma processing apparatus using the same. The electrostatic chuck includes an insulating layer, and a thermal barrier layer below the insulating layer. By selecting a material with smaller thermal conductivity as the thermal barrier layer disposed between the heating device and the base, it can effectively reduce the heat transmission rate from the heating device to the base, thereby forming a greater temperature gradient between the electrostatic chuck and the base so as to maintain normal plasma treatment process of the substrate above the electrostatic chuck. In view of the smaller thermal barrier layer thickness in thermal spray-coating process, two thermal barrier layers are coated below the insulating layer and on the base, which are bonded by adhesive layer to better improve the temperature gradient between the electrostatic chuck and the base.

Description

Plasma processing device, electrostatic chuck and electrostatic chuck manufacturing method

The present invention relates to the field of plasma processing technologies, and in particular, to an electrostatic chuck and a technical field thereof.

In the plasma processing process, Electro Static Chuck (ESC) is often used to fix, support and transfer the substrate (Wafer) to the workpiece. The electrostatic chuck is disposed in the reaction chamber, and the electrostatic chucking method is used instead of mechanically fixing the substrate, which can reduce the possible mechanical loss to the substrate and completely contact the electrostatic chuck with the substrate, thereby facilitating heat conduction. . During the reaction, a reaction gas is introduced into the reaction chamber, and RF power is applied to the reaction chamber. Usually, the RF power is applied to the conductor base under the electrostatic chuck. The RF power mainly includes the RF source power and the RF bias power, and the RF The source power and the RF bias power work together to ionize the reaction gas to generate a plasma, and the plasma and the substrate undergo a plasma reaction to complete the processing of the substrate.

The electrostatic chuck heats the substrate while the plasma is etched on the fixed support substrate to reach the target temperature, ensuring the efficiency of the plasma and substrate reaction. To this end, it is necessary to provide a heating device inside the electrostatic chuck, such as a heating wire, and to heat the heating wire to realize heating of the electrostatic chuck by the heating wire. In order to control the temperature of the electrostatic chuck, it is also necessary to design a device capable of lowering the temperature of the electrostatic chuck to prevent the temperature of the electrostatic chuck caused by the heating device from continuously rising. Currently commonly used cooling devices are usually placed inside the base, using a water-cooled structure above the base The electrostatic chuck is cooled.

In order to facilitate heating of the substrate, usually the heating device is disposed inside the heat conducting layer having a good thermal conductivity. At this time, the heat conducting layer is simultaneously in contact with the susceptor, and the water-cooling structure inside the susceptor can easily lower the temperature of the heating device. Therefore, the heat of the heating device cannot be transferred to the substrate in time, and the temperature gradient between the water-cooling structure of the heating device and the pedestal is too small, which is not conducive to the smooth progress of the process.

In order to solve the above technical problem, the present invention discloses a plasma processing apparatus including a vacuum reaction chamber, an electrostatic chuck supporting a substrate is disposed under the vacuum reaction chamber, and a pedestal is disposed under the electrostatic chuck. The electrostatic chuck includes an insulating layer internally provided with a DC electrode, and a heat resistant layer having a material having a low thermal conductivity is disposed under the insulating layer, and a thermal conductivity of the thermal resist material is less than or equal to 10 W/mK.

Preferably, the electrostatic chuck further comprises a heating device located between the thermal barrier layer and the insulating layer or inside the thermal barrier layer.

Preferably, the material of the heat blocking layer is alumina or cerium oxide or a mixture of aluminum oxide and cerium oxide.

Preferably, the thermal barrier layer comprises a first thermal barrier layer and a second thermal barrier layer, and a bonding layer is disposed between the first thermal barrier layer and the second thermal barrier layer.

Preferably, the first heat blocking layer and the second heat blocking layer material are the same or different.

Further, the present invention also discloses an electrostatic chuck, the electrostatic chuck is located above a pedestal, and the electrostatic chuck comprises an insulating layer internally provided with a DC electrode and is located at the A heat-resistant layer having a material having a low thermal conductivity under the edge layer, and a heating device disposed between the heat-resistant layer and the insulating layer or inside the heat-resistant layer.

Preferably, the thermal barrier layer comprises a first thermal barrier layer and a second thermal barrier layer, and a bonding layer is disposed between the first thermal barrier layer and the second thermal barrier layer.

Further, the present invention also discloses a method for manufacturing an electrostatic chuck, comprising the steps of: thermally spraying a first heat-resisting layer on a back surface of an insulating layer provided with a DC electrode therein, and setting a heating device in the spraying process a second heat-resisting layer is thermally sprayed on a surface of the susceptor; a bonding layer is disposed on the lower surface of the first heat-resisting layer or the upper surface of the second heat-resisting layer, and the bonding layer is first resistive The thermal layer and the second heat resistant layer are bonded and fixed to fix the electrostatic chuck to the base.

Preferably, the heat resist layer material has a heat transfer coefficient of 10 W/m·K or less.

Preferably, the material of the heat blocking layer is alumina or cerium oxide or a mixture of aluminum oxide and cerium oxide.

Preferably, the materials of the first heat blocking layer and the second heat blocking layer are the same or different.

An advantage of the present invention is that the present invention discloses an electrostatic chuck, a method of fabricating the same, and a plasma processing apparatus therefor, the electrostatic chuck comprising an insulating layer and a thermal barrier layer under the insulating layer. By selecting a material with a small heat transfer coefficient as a heat blocking layer, it is disposed between the heating device and the base, which can effectively reduce the rate of heat generated by the heating device to the susceptor, and facilitate formation between the electrostatic chuck and the pedestal. Large temperature gradient maintains the normal plasma treatment process of the substrate above the electrostatic chuck. Considering the small thickness of the thermal barrier layer produced by the thermal spraying process, two layers of thermal barrier can be thermally sprayed under the insulating layer and above the pedestal respectively. , bonding with a bonding layer The temperature gradient between the electrostatic chuck and the pedestal is better improved.

100‧‧‧vacuum reaction chamber

110‧‧‧ lower electrode

115‧‧‧Cooling runner

120‧‧‧Electrostatic chuck

121‧‧‧Insulation

122‧‧‧heat barrier

1221‧‧‧First heat barrier

1222‧‧‧second thermal barrier

1223‧‧‧Bonded layer

125‧‧‧DC electrode

126‧‧‧ heating device

130‧‧‧ gas supply

140‧‧‧Substrate

150‧‧‧Upper electrode

160‧‧‧ Plasma

170‧‧‧RF power source

180‧‧‧Air pump

Fig. 1 is a schematic view showing the structure of a plasma processing apparatus according to the present invention.

2 is a schematic structural view of an electrostatic chuck according to the present invention.

FIG. 3 is a schematic structural view of an electrostatic chuck according to another embodiment of the present invention.

The present invention discloses a plasma processing apparatus, an electrostatic chuck, and a method for manufacturing an electrostatic chuck. The above objects, features and advantages of the present invention will become more apparent and understood. The embodiment will be described in detail.

The technical solution described in the present invention is applicable to a capacitive coupling type plasma processing apparatus or an inductively coupled type plasma processing apparatus, and other plasma processing apparatuses that use an electrostatic chuck to heat the temperature of a substrate to be processed. Illustratively, FIG. 1 is a schematic view showing the structure of a plasma reaction chamber according to the present invention; the plasma reaction chamber is a capacitive coupling type plasma reaction chamber, and the technical solution disclosed by the present invention is not inventive. All modifications made by labor are within the scope of protection of the present invention.

1 is a schematic view showing the structure of a capacitive coupling type plasma reaction chamber, comprising a substantially cylindrical vacuum reaction chamber 100. The vacuum reaction chamber 100 is provided with upper and lower corresponding upper electrodes 150 and lower electrodes 110, and the upper electrode 150 is connected to a gas supply. In the device 130, the upper electrode 150 simultaneously serves as a gas distribution plate for the reaction gas to uniformly enter the plasma reaction chamber; the lower electrode 110 is connected to the RF power source 170, and the electrostatic chuck 120 is supported above the electrostatic chuck 120 for supporting the substrate 140. The working principle of the plasma reaction chamber in this embodiment is that the upper electrode 150 and the lower electrode 110 are in the RF work. Under the action of the rate, the gas injected into the plasma reaction chamber 100 is dissociated to generate a plasma 160, and the plasma 160 physically bombards or chemically reacts the substrate 140 to realize processing of the substrate 140. The by-products after the reaction and the exhausted gas are discharged from the plasma reaction chamber 100 through the air pump 180.

2 is a schematic view showing the structure of the electrostatic chuck of the present invention. As shown in FIG. 2, the electrostatic chuck 120 is disposed above the susceptor 110 for carrying the substrate 140. The electrostatic chuck 120 includes an insulating layer 121. The insulating layer is internally provided with a DC electrode 125. The DC electrode is connected to a DC power source (not shown). The DC power source acts on the DC electrode 125 to generate an electrostatic attraction on the surface of the electrostatic chuck 120. The substrate 140 is fixed. A heat blocking layer 122 is disposed under the insulating layer 121, and the heat conductive layer material has a low heat transfer coefficient. The heating device 126 is disposed between the heat-resisting layer 122 and the insulating layer 121 or the heat-resisting layer 122. In this embodiment, the heating device 126 is disposed inside the heat-resistant layer 122, and may also be disposed adjacent to the lower surface of the insulating layer 121. The heating device is typically a heating wire for heating the electrostatic chuck 120 to conduct heat through the electrostatic chuck 120 to the substrate 140. Since the heat transfer coefficient of the material of the heat blocking layer 122 is small, in order to ensure that the heat generated by the heating device 126 can be transferred to the substrate 140 as soon as possible, the heating device 126 may be disposed between the heat blocking layer 122 and the insulating layer 121, if disposed in the heat resistance layer. The inside of the layer 122 may be disposed at a position above the heat blocking layer 122. The heat blocking layer 122 is in contact with the upper surface of the pedestal to ensure that the electrostatic chuck 120 is seated above the susceptor 110.

According to the above description, the electrostatic chuck 120 heats the substrate 140 while the plasma is etched by the fixed supporting substrate 140 to reach the target temperature, ensuring the efficiency of the plasma and substrate reaction. In order to avoid the temperature of the electrostatic chuck caused by the heating device continuously rising, it is also necessary to design a device capable of lowering the temperature of the electrostatic chuck to achieve an adjustable temperature rise and fall of the electrostatic chuck 120. Currently, the commonly used cooling device is usually disposed inside the base, such as in the base 110. There is a coolant flow path 115 which is typically used to inject coolant to cool the electrostatic chuck. In the prior art, the heating device is usually disposed inside a material having a good heat conductive material, and the heat generated by the heating device can be quickly transferred to the substrate through the heat conductive material to bring the substrate to a desired temperature to react with the plasma. However, while the heat conductive material transfers the heat upward to the substrate, the heat is quickly transferred to the coolant passage 115 of the base, so that the heat generated by the heating device 126 is excessively lost, and the heating device 126 cannot be cooled with the coolant. The desired temperature gradient is maintained between channels 115.

For the above reasons, the heat-resistant layer material having a low thermal conductivity between the electrostatic chuck 120 and the susceptor 110 in the second embodiment of the present invention can delay the rate at which heat is conducted to the susceptor. According to the heat transfer formula Q = K * ΔT / d. Where Q is the heat per unit area, and the heat Q per unit area can be calculated by the ratio of the heating power of the heating device 126 to the area of the electrostatic chuck 120; K is the heat transfer coefficient of the material layer, and ΔT is the temperature gradient, that is, heating The temperature difference between the device 126 and the coolant passage 115; d is the heat transfer distance. The material of the heat-resistant layer 122 of the present invention may be alumina or cerium oxide or a mixture of aluminum oxide and cerium oxide. The thermal conductivity of alumina is 3.55 W/mK, and the thermal conductivity of cerium oxide is less than 2 W/mK. The titanium alloy heat conduction layer in the technology has a heat conduction coefficient of about 20 W/mK, and the aluminum alloy heat conduction layer has a heat conduction coefficient of about 170 W/mK. The heat resistance layer of the invention can effectively delay the heat conduction from the heating device to the susceptor. . Ensure that there is a large temperature gradient between the electrostatic chuck and the base.

The thickness of the thermal barrier layer 122 is also an important factor determining the temperature gradient between the electrostatic chuck 120 and the susceptor 110. Since the thermal barrier layer of the present invention thermally sprays aluminum oxide or cerium oxide or a mixture thereof to the back of the insulating layer, Limited to the limitations of current thermal spraying processes, the thickness of the aluminum oxide or yttria heat-resistant layer can only be made smaller, usually less than 1 mm, and cannot meet the needs of a plasma processing apparatus that requires a large temperature gradient. For this purpose, it can be set on the electrostatic chuck A method of providing two heat-insulating layers between the insulating layer and the pedestal increases the thickness of the heat-generating layer 122.

As shown in FIG. 3, the heat blocking layer 122 includes a first heat blocking layer 1221 and a second heat blocking layer 1222. The first heat blocking layer 1221 is thermally sprayed onto the back surface of the insulating layer 121. During the thermal spraying process, the heating device is heated. 126 is disposed inside the first heat blocking layer 1221. The second heat-resisting layer 1222 is thermally sprayed on the upper surface of the susceptor 110. The material of the second heat-resisting layer 1222 may be the same as or different from the first heat-resisting layer material, and may be on the lower surface or the second surface of the first heat-resisting layer 1221. The upper surface of the heat blocking layer 1222 is provided with a bonding layer 1223. The bonding layer 1223 can bond the first heat blocking layer 1221 and the second heat blocking layer 1222 together to increase the thickness of the heat blocking layer 122. The material of the bonding layer 1223 can be Tannin or Teflon film, because of the small heat transfer coefficient of silicone and Teflon, can effectively block the conduction of heat, and help to form a large temperature gradient between the electrostatic chuck 120 and the susceptor 110. At the same time, when the thermal insulation layer 122 is thermally sprayed, adding other materials having a small thermal conductivity to yttrium oxide or aluminum oxide can also lower the heat transfer coefficient of the entire thermal resistance layer, thereby achieving a higher temperature between the electrostatic chuck and the susceptor. gradient.

The invention adopts at least one heat-resisting layer with a small heat conduction coefficient between the heating device and the base, which can reduce the rate of heat generated by the heating device to the pedestal, and facilitates formation between the electrostatic chuck and the pedestal. The temperature gradient maintains the normal plasma treatment process of the substrate above the electrostatic chuck. Preferably, the thermal conductivity layer material has a thermal conductivity of less than 10 W/mK. In addition, the present invention also discloses an electrostatic chuck and an electrostatic chuck designed by the above solution, which are described in detail above, and are not described herein again.

The present invention is disclosed in the above preferred embodiments, but it is not intended to limit the present invention, and any one skilled in the art can make possible variations and modifications without departing from the spirit and scope of the invention. The scope of protection should be defined by the claims of the present invention The scope is subject to.

100‧‧‧vacuum reaction chamber

110‧‧‧ lower electrode

120‧‧‧Electrostatic chuck

130‧‧‧ gas supply

140‧‧‧Substrate

150‧‧‧Upper electrode

160‧‧‧ Plasma

170‧‧‧RF power source

180‧‧‧Air pump

Claims (11)

A plasma processing apparatus includes a vacuum reaction chamber, an electrostatic chuck supporting a substrate is disposed under the vacuum reaction chamber, and a base is disposed under the electrostatic chuck, wherein the electrostatic chuck includes an internal portion An insulating layer is provided with a DC electrode, and a heat-resistant layer having a material having a low thermal conductivity is disposed under the insulating layer, and a thermal conductivity of the heat-resistant layer material is 10 W/mK or less. The plasma processing apparatus of claim 1, wherein the electrostatic chuck further comprises a heating device, the heating device being located between the thermal barrier layer and the insulating layer or at the Inside the thermal barrier. The plasma processing apparatus according to claim 1, wherein the material of the heat-resistant layer is alumina or cerium oxide or a mixture of aluminum oxide and cerium oxide. The plasma processing apparatus of claim 1, wherein the thermal barrier layer comprises a first thermal barrier layer and a second thermal barrier layer, the first thermal barrier layer and the second thermal barrier layer A bonding layer is provided between them. The plasma processing apparatus of claim 4, wherein the first heat blocking layer and the second heat blocking layer material are the same or different. An electrostatic chuck, the electrostatic chuck is disposed above a pedestal, wherein the electrostatic chuck comprises an insulating layer internally provided with a DC electrode and a heat resistant layer having a material with a low thermal conductivity under the insulating layer. A heating device is disposed between the heat blocking layer and the insulating layer or inside the heat blocking layer. The plasma processing apparatus of claim 6, wherein the thermal barrier layer comprises a first thermal barrier layer and a second thermal barrier layer, the first thermal barrier layer and the second resistance Thermal layer A bonding layer is provided between them. A method for manufacturing an electrostatic chuck, comprising the steps of: thermally spraying a first heat-resisting layer on a back surface of an insulating layer provided with a DC electrode therein, and disposing a heating device inside the heat-resistant layer during spraying a second heat-resisting layer is thermally sprayed on a surface of the susceptor; a bonding layer is disposed on the lower surface of the first heat-resisting layer or the upper surface of the second heat-resisting layer, the bonding layer is a first heat-resisting layer and The two heat resistant layers are bonded and fixed, and the electrostatic chuck is fixed to the base. The method for producing an electrostatic chuck according to claim 8, wherein the first heat-resistant layer and the second heat-resistant layer material have a heat transfer coefficient of 10 W/m·K or less. The method for producing an electrostatic chuck according to claim 8 is characterized in that the first heat blocking layer and the second heat blocking layer material are alumina or cerium oxide or a mixture of aluminum oxide and cerium oxide. The method for fabricating an electrostatic chuck according to claim 8 is characterized in that the materials of the first heat blocking layer and the second heat blocking layer are the same or different.