KR100920132B1 - Electrostatic chuck with detachable ring and manufacturing method thereof - Google Patents

Abstract

The present invention relates to an electrostatic chuck having a detachable ring, the lower electrode of the same material as the upper electrode, bonded to the sheet using a silicone-based adhesive, the upper electrode formed on the lower electrode, A ring formed on an outer circumferential portion and separable from the electrostatic chuck, the surface of the ring having an insulating coating formed on the top surface of the sheet, wherein the insulating ring is formed using anodization or thermal spray coating; It is characterized by.

Detachable ring, electrostatic chuck, insulation coating.

Description

Electrostatic Chuck having a separable ring and Fabricating method of the same}

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

2 is a cross-sectional view of a conventional hard anodizing electrostatic chuck.

Explanation of symbols on the main parts of the drawings

100, 200: electrostatic chuck 201: lower electrode

202: upper electrode 209: sheet

The present invention relates to an electrostatic chuck (ESC) and a method of manufacturing the same, which are used in the Etcher, the Chemical Vapor Deposition equipment, which are the preprocessing equipment, in the semiconductor and liquid crystal display manufacturing apparatus. In particular, the present invention relates to an electrostatic chuck having a detachable ring suitable for application to a process with high damage by a reaction product or plasma, and which can prevent long life and damage and a method of manufacturing the same. will be.

The prior art is largely Top-Side Mechanical Clamping technology and Electro-Static Clamping technology, the main current is the Electro-Static Chuck System, in the present invention The prior art will be expressed mainly on the system.

The electrostatic clamping method is mainly Coulomb force and Johnson Lavecque, with electrostatic stabilization for stable chucking of wafers in a single wafer processing device or for uniform temperature control. (Johnsen-Rahbek force) is used. In order to obtain such electrical attraction force, the wafer and the lower electrode have a parallel plate capacitor structure.

Two electrodes include an electrode on which a wafer is placed (also referred to as a lower electrode) and the wafer itself is used as an electrode, and in the middle, the semiconductor or insulator material is coated with a necessary thickness as a capacitor insulating material. When using Johnson Lavecque, the surface roughness of the insulating material in contact with the wafer greatly affects the force.

Since the electrostatic chuck uses electrical force, it must be perfectly configured in electrical circuit to operate normally. For connection between power and ground, plasma is used as a conductor (actually as the concept of resistance). Dechucking is performed.

Since thermal energy is generated on the semiconductor wafer during the processing of the semiconductor wafer, failure to release the thermal energy efficiently causes the semiconductor wafer to locally expand and deform. Therefore, it is very important to release heat generated during processing through the chuck device and to make the semiconductor temperature distribution uniform.

The conventional electrostatic chuck device 100 has an adhesive layer 102 on a hard anodized metal substrate 101 (hereinafter referred to as a lower electrode) as shown in FIG. The insulating plate 103 is laminated. Then, the insulator layer 107 is laminated on the insulating plate 103 in order, the adhesive layer 104, the upper electrode layer 105 made of a metal thin plate, the adhesive layer 106, and finally affects the performance of the electrostatic force. Are stacked. Here, reference numeral 108 denotes a wafer.

The adsorption force of the electrostatic chuck 100 is directly affected by the thickness of the coating material, the dielectric constant of the coating material and the applied voltage, and in particular, the coating material loses its function as a resistance by a specific voltage. It is essential to control the applied voltage below the breakdown voltage.

The wafer 108 is adsorbed by the electrostatic force on the insulating layer 107 and the cooling water or the antifreeze is designed to flow at a constant temperature and flow rate in the lower electrode 101 to maintain a constant temperature of the lower electrode 101. .

More specifically with respect to the prior art, as shown in FIG. 2, the wafer 108 is loaded into a process chamber (not shown) by the transfer system to allow the gas 109 to proceed with the necessary process. Is introduced into the process chamber by a flow control system (generally MFC; not shown) and maintains the pressure set by the pressure regulator 110 connected between the vacuum pump 111 and the process chamber. DC power is generated from the DC power supply 112 and applied to the upper electrode layer 105 in order to generate an electrical attraction force on the back surface of the wafer 108. As the DC power is applied, the polarization of the insulating coating materials 103 and 107 occurs, and the polarization phenomenon depends on the material of the coating material, the applied voltage, the coating thickness, the dielectric constant of the coating material, the surface roughness, and the like. Adsorption force is greatly dependent not only on the above-mentioned items but also on the wafer 108 area, the pressure in the chamber, the temperature, the back press, the flatness of the contact surface, and the like.

Depending on the electrostatic chucking method used and the coating material used, RF power 113 and cooling gas for cooling the wafer backside (generally using helium) are applied simultaneously or sequentially as electrical energy for plasma formation. .

RF, which is electrical energy, is applied to the lower electrode 101 and passed through various layers of insulators formed on the lower electrode 101. The wafer 108 and the lower electrode 101 are chucked using Coulomb force or Johnson Lavec force by a gas-mediated plasma separated into ions and electrons by the transmitted RF energy.

In the state where the plasma is still present, the adsorption force is maintained according to the characteristics of the coating material, and the adsorption DC power and the cooling gas for cooling the wafer back are turned off before and after the plasma is turned off after the completion of the process. However, although the electrical circuit has been opened, the polarization of the coating material is not completely eliminated because there is no material with substantially infinite resistance. Therefore, in order to remove the residual charge present on the back of the wafer, an antistatic step of neutralizing and removing the residual charge using only the plasma without applying DC power is further used.

Therefore, the above-described prior art has the following problems.

1. Since the materials of the lower electrode 101 and the sheet (Sheet) are different, and there is a difference in the coefficient of thermal expansion, there is a risk of cracking due to stress caused by temperature rise and fall, and the sheet 114 is bent or the like. This can happen.

2. Since the adhesive is used on the side of the sheet 114, there is a problem that not only shortens the life of the electrostatic chuck 100 by arcing, but also shortens the life of other etching components.

3. The outer circumferential portion of the upper surface on which the wafer 108 is seated may be etched by the activated ions and radicals in the plasma state to cause process defects due to particle generation and uneven etching rate.

4. Since the insulation layer is multi-layered, the electrical connection between the alternating current RF power and the direct current DC power is very complicated, so the power transmittance is affected by the dielectric constant difference.

5. Since a plurality of insulating films are stacked to increase the insulation between the lower electrode 101 and the upper electrode 105, it is difficult for heat of the semiconductor wafer 108 to be transferred to the lower electrode 101. Inadequate temperature control.

6. As shown in FIG. 2, unevenness occurs due to the thickness of the upper electrode 105 on the adsorption surface of the wafer 108 between the portion with and without the upper electrode 105 made of a metal thin plate. In the uneven portion, since a space is generated between the wafer 108 and the suction surface, the thermal conductivity deteriorates locally.

7. Smaller adhesives improve thermal conductivity, but the thickness of adhesives may be more than 50um to ensure sufficient insulation.

8. When the thermosetting resin is used as the adhesive layer, the lower electrode 101 or the like may be damaged since the thermosetting resin should be removed by a physical method rather than a chemical method for regeneration.

Accordingly, an object of the present invention is to solve the above-described problems of the prior art, which ultimately improves the thermal conductivity of the electrostatic chuck device and facilitates the exchange of insulating materials having heat shrinkage, matching of expansion, and adsorption surfaces. An electrostatic chuck having a possible ring and a method of manufacturing the same are provided.

As shown in FIG. 1, the electrostatic chuck 200 according to the present invention largely includes a lower electrode 201 and a sheet 209. More specifically, the electrostatic chuck 200 uses a lower electrode 201 and the lower electrode 201 maintains flatness, and a thin insulating coating layer 207 is formed at the top of the sheet 209, wherein the insulating film The formation of the fields 203, 204, and 205 may be performed by anodizing or any of spray coating methods. However, the required insulating properties should be maintained and usually 10 ¹⁴ Ωcm or more is preferable.

The conductive connecting rod 208 to which the DC power supply 212 is applied may be made of a material having good conductivity and easy to form an insulating film on its surface, and aluminum is usually used. In addition, the connecting rod 208 is mounted to the electrostatic chuck 200 detachably in a screw type. An insulating film 203 is formed on the surface of the upper electrode 202. The insulating film 203 is formed by anodizing or thermal spray coating. Since the back surface of the upper electrode 202 has to be in electrical contact with the lower electrode 201, surface roughness and physical properties are not important, but an insulating film formed under the portion where the wafer is to be placed (that is, the top surface of the insulating coating layer 207). The insulating film 203 is polished because 203 preferably has excellent surface roughness as well as excellent insulation characteristics, withstand voltage, and the like. The insulating film 203 polishing method uses a polishing powder, wherein the surface roughness Ra is to maintain 0.1 ~ 0.8um. Next, an insulating coating layer 207 is formed on the insulating film 203. A conductive connecting rod 208 is installed as shown in FIG. 1 to independently connect the DC power supply 212 to the upper electrode 202. The conductive connecting rod 208 is insulated using an insulating plastic material having a similar thermal expansion coefficient to the base material of the lower electrode 201 in consideration of electrical insulation and thermal expansion coefficient. In order to protect the side surface of the electrostatic chuck 200, a detachable ring 206 is manufactured as shown in FIG. 1 and inserted into an outer circumferential portion of the upper electrode 202. Since the detachable ring 206 must have the same thermal expansion coefficient as that of the electrostatic chuck 200, the same material is used, and the ring 206 is formed by forming an insulating film 205 in a circular conductive material.

The ring 206 is electrically insulated from the lower electrode 201 and the upper electrode 202. After the plasma is formed, the ring 206 serves as a blocking function for activated ions or radicals in the plasma, thereby preventing the electrostatic chuck ( Protect the sides of the 200).                     

Subsequently, the operation of the present invention will be described in detail.

Referring to FIG. 1, in the present invention, a wafer (not shown) is loaded into a processing chamber (not shown) by a conveying system (not shown) and gas is flowed into a flow control system (not shown). It is generally known in the art that the valve is operated by MFC (not shown) to operate in order to maintain the pressure set by a vacuum pump (not shown) and a pressure regulator connected between the processing chamber and a vacuum pump (not shown). It is.

DC power is generated from the DC power supply 212 and applied to the upper electrode 202 through the connecting rod 208 to generate an electrical attraction force on the back surface of the wafer. The object to be adsorbed can be adsorbed not only on the semiconductor wafer but also on a material having conductivity or semiconductivity. The insulating film 203 and the insulating coating layer 207 that maintain the adsorption force are simply anodized or coated with a thermal spray coating, and the structure is simple, and the bending due to the difference in thermal expansion coefficient is achieved by using the same base material. It can be prevented fundamentally.

The wafer adsorption surface can form radial or similar grooves as needed to aid the flow of the fruit medium.

In the process such as dry etching, the wafer temperature control is a key point, so that various types of cooling gas flow on the surface in contact with the wafer to control heat, and another function of the electrostatic chuck 200 is not only temperature control but also misalignment of the wafer. It is also applied as a function to prevent misalignment and to secure the wafer. In this case, the electrostatic chuck manufacture does not have to be so complicated, since only the required static power is obtained.

The surface in contact with the wafer can be simply adjusted by the surface roughness by polishing, and the thickness can also be easily adjusted without the adhesive layer. In addition, to protect the electrostatic chuck 200 in a harsh environment such as plasma, by inserting a detachable ring 206 that is not significantly related to electrostatic power, deterioration of electrostatic power can be prevented. I have made this easy. In consideration of the coefficient of thermal expansion, the ring 206 material is preferably the same material as the sheet 209 and the lower electrode 201.

The adhesive layers 210 and 211 used for the bonding between the lower electrode 201 and the sheet 209 and the ring 206 apply a jelly-type silicone adhesive system in which a filler is inserted to function as a thermal buffer. . According to the experiments of the present inventors, the viscosity of the silicone adhesive is practically about 20 to 50 Pa · s and the thermal conductivity is suitably 15 W / mk.

While the present invention has been described above, those skilled in the art should appreciate that many other applications are possible without departing from the spirit and scope of the present invention.

According to the above configuration, the following effects can be obtained.

1. It is not necessary to laminate several kinds of insulating materials through the adhesive layer to manufacture the sheet. Mixing materials with different dielectric constants and coefficients of thermal expansion can cause fatal errors in the stability of electrostatic forces.                     

2. The lower electrode supporting the wafer, the sheet that absorbs the wafer with electrostatic force, and the ring that receives damage by plasma etc. on the side apply the same material, so it is easy to manufacture and perfect thermal conductivity is achieved. Therefore, it is possible to fundamentally solve problems such as cracks due to temperature rise and fall, and fundamentally solve problems such as warpage.

3. The lower electrode, seat, and ring are manufactured separately and assembled, so it is easy to replace when certain parts are worn or damaged.

4. Use a silicone-based easy-to-separator adhesive and insert a filler in the form of a metal ball to even out the heat distribution.

5. The electrostatic power is easy to manufacture and improve because it is simplified to variables that influence the electrostatic power such as the top thickness and surface roughness of the electrostatic layer.

6. Since the lower electrode, the sheet and the ring have the same coefficient of thermal expansion, the stress (stress) of the lower electrode and the sheet can be minimized.

7. The insulating film on the sheet surface can be easily manufactured by anodization or thermal spray coating, so it is easy to control the manufacturing period and electrostatic power.

8. It is easy to control the flow of cooling gas by processing the sheet surface as needed.

Claims (9)

A lower electrode having an insulating film formed on the upper surface by using anodization or thermal spray coating; A sheet disposed on the insulating layer of the lower electrode, the sheet including an insulating layer formed on the entire surface of the upper electrode and the upper electrode by using anodization or thermal spray coating; A ring disposed on the lower electrode to surround the outer circumferential portion of the sheet and having an insulating film formed on the entire surface by using anodization or thermal spray coating; And Including an insulating coating layer formed on the top surface of the sheet, And the ring, the lower electrode, and the upper electrode are made of the same material, and the insulating film of the ring, the insulating film of the lower electrode, and the insulating film of the upper electrode are made of the same material. delete delete delete The electrostatic chuck of claim 1, further comprising an electrode connecting rod connected to the upper electrode, wherein the electrode connecting rod is formed in a screw type and fastened toward the upper electrode through the lower electrode. The electrostatic chuck of claim 1, wherein the mutual bonding between the ring, the lower electrode, and the sheet uses an adhesive having the same coefficient of thermal expansion. 7. The electrostatic chuck of claim 6, wherein the adhesive is a silicone jelly adhesive and has a viscosity in the range of 20 to 50 Pa · s and a thermal conductivity of 1 to 5 W / mk. 8. The electrostatic chuck of claim 7, wherein the silicone jelly adhesive has a metal filler inserted therein. Providing a lower electrode having an insulating film formed on the upper surface by using anodization or thermal spray coating; Forming a sheet on the lower electrode, the sheet including an upper electrode and an insulating film formed on the entire surface of the upper electrode by using anodization or thermal spray coating; Forming a ring having an insulating film over its entire surface using an anodization or a thermal spray coating on the lower electrode to surround the outer circumferential portion of the sheet; And Forming an insulating coating on the top surface of the sheet; And the ring, the lower electrode, and the upper electrode are made of the same material, and the insulating film of the ring, the insulating film of the lower electrode, and the insulating film of the upper electrode are made of the same material.

Images