KR20010058837A - Wafer holding chuck - Google Patents

Abstract

PURPOSE: A wafer holding chuck is to prevent a wafer from being damaged due to current without using a static electricity and to improve productivity and stably mount and detach the wafer by simply forming an electric constitution. CONSTITUTION: A chemical vapor deposition apparatus comprises a chamber(21) for depositing a thin film on a wafer, an exhaust tube for discharging a by-product generated in the chamber, a pump(23) for maintaining the inside of the chamber at a constant low pressure, a flow control unit(24) for controlling amount of a supplied depositing gas, a lower electrode(25) on which the wafer is mounted and to which a RF voltage is applied, an upper electrode(26) to which the RF voltage is also applied and a cold air supplying unit(27) connected to one side of the lower electrode for cooling the wafer. A wafer holding chuck(30) having a side detachable unit(40) is provided to the lower electrode. The side detachable unit comprises a pressure ring(41) to be contacted with a side of the wafer, an elastic member(42) for applying a resilient force to mount the wafer and a separating motion unit(43) for separating the wafer by moving the pressure ring outwards.

Description

Wafer Holding Chuck {WAFER HOLDING CHUCK}

The present invention relates to a wafer holding chuck, and more particularly, the present invention can solve the problems of the electric chuck by installing a side detachment means for mounting and removing the side of the wafer located on the lower electrode of the vapor deposition equipment. A wafer holding chuck.

In general, the semiconductor chemical vapor deposition process is a thin film formation method in which a thin film or particles synthesize a solid material through a chemical reaction from a gas raw material to form a thin film on a predetermined surface. The process diagram of the semiconductor low pressure chemical vapor deposition process for depositing a thin film by chemical reaction at a low pressure of 0.1 ~ 10 torr of the reactor port is shown.

As shown in the drawing, when the wafer is placed in the reaction chamber A, which is cut off from the outside, and gas is supplied to the raw material through the gas supply unit B, thermal decomposition is performed by the heat supplied from the heating unit C and the energy unit D. It refers to a method of forming a thin film without changing the properties of the substrate and the unreacted material is discharged through the exhaust portion (E).

FIG. 2 is a schematic view of a semiconductor low pressure chemical vapor deposition apparatus generally used. As shown in the drawing, a conventional low pressure chemical vapor deposition apparatus includes a chamber 1 in which deposition gas is injected to deposit a thin film on an upper surface of a wafer W. As shown in FIG. And, the exhaust pipe (2) for discharging the by-products generated by the unreacted deposition gas in the chamber (1), the pump (3) for removing the deposition gas in the chamber (1) to maintain a constant low pressure and And a flow rate control unit 4 which constantly controls the supply amount of the deposition gas, a lower electrode 5 to which the wafer is seated in the chamber 1 and to which a DC power source and an RF power source are applied, and the lower electrode 5. And an upper electrode 6 to which an RF power is applied, and a cold air supply unit 7 connected to one side of the lower electrode 5 to cool the wafer.

In addition, the lower electrode 5 is generally provided with an electrostatic chuck 10 that uses an electric force by a coulomb, and a focus ring 11 is provided on one side of the lower electrode 5, and is in contact with the wafer. On the upper surface of the electrode 5, a coating 12, which acts as an insulator and generates polarization, is formed to a predetermined thickness.

Referring to the operation of the conventional electrostatic chuck configured as described above are as follows.

As shown in FIG. 2, when the wafer is brought into the chamber 1, a deposition gas is supplied into the chamber 1, and a predetermined pressure is maintained by the pump 3.

In addition, when a direct current power source is applied to the lower electrode 5 to generate electrical adhesion on the back surface of the wafer, a polarization phenomenon is generated in the coating 12 formed of the insulating material, and the polarization phenomenon is the coating 12. It depends not only on the material, applied voltage, coating thickness, dielectric constant of the coating, etc. but also on various variables related to the area of the wafer, the pressure and temperature in the chamber, the back press, the flatness of the contact surface, and the like.

In particular, since the adhesion force of the electrostatic chuck has an electrical breakdown voltage (Break Down) that loses its function as a resistance by a specific voltage, the applied voltage must be controlled below the breakdown voltage.

When an RF power is applied, plasma is generated and deposition is performed. The wafer and the lower electrode 5 are electrically attached to each other by an electric force generated by a coulomb, and the cold air supply unit 7 cools the wafer. Is supplied to cool the back side of the wafer.

On the other hand, in the state in which the plasma is generated, the adhesion force due to static electricity is maintained according to the characteristics of the coating 12, the DC power supply and the cold air supply unit 7 of the DC power supply after the completion of the deposition process or before or after the generation of the plasma is finished The operation ends.

However, even when the process is terminated and the electrical circuit is cut off, since the resistance of the material is not infinite, the polarization phenomenon of the coating 12 does not completely disappear, and residual charge exists on the back surface of the wafer. In order to remove the residual charge, a neutralization step is performed by using a plasma without applying DC power.

However, the conventional electrostatic chuck uses an electrical polarization phenomenon, so that the wafer is damaged by the current, and the factors affecting the adhesion force of the electrostatic chuck are complicated, making it difficult to repeatedly reproduce the same process. In addition, productivity is reduced because an antistatic process for removing residual charges is added, and the residual charges are not completely removed. Meanwhile, a DC power source must be connected to the lower electrode and a plasma is generated to operate the electrostatic chuck. The electrical configuration had a complicated problem.

The present invention has been made to solve the problems of the prior art as described above, the object of the present invention is to provide a wafer holding chuck that can stably mount and remove the wafer without using the static electricity generated by the electrical polarization phenomenon To provide.

1 is a process chart showing a semiconductor chemical vapor deposition process.

Figure 2 is a schematic diagram of a conventional chemical vapor deposition equipment.

Figure 3 is a schematic diagram of a chemical vapor deposition apparatus equipped with a wafer holding chuck according to the present invention.

Figure 4a is a plan view of the pressing ring in the wafer holding chuck in accordance with the present invention.

Figure 4b is a cross-sectional view showing the contact portion of the pressure ring and the wafer in the wafer holding chuck in accordance with the present invention.

5A is a plan view of a lower electrode in a wafer holding chuck in accordance with the present invention;

5B is a cross-sectional view taken along the line AA ′ of FIG. 5A.

<Description of Symbols for Major Parts of Drawings>

21 chamber 22 exhaust pipe

23: pump 24: flow control unit

25: lower electrode 26: upper electrode

27: cold air supply unit 30: wafer holding chuck

40: side detachable means 41: pressure ring

41a: arc recess 42: elastic member

43: stripping ball 50: spiral cooling slot

51: canyon 52: cylindrical portion

In order to achieve the above object, the wafer holding chuck according to the present invention is characterized in that it comprises a side detachment means for reciprocating in the normal direction of the wafer located on the lower electrode to mount and remove the side of the wafer.

The side detachable means includes a pressure ring cut in plural numbers with respect to the diameter of the wafer so as to be in contact with the side surface of the wafer, an elastic member provided on an outer circumferential side of the pressure ring to apply an elastic force to mount the wafer, and an inner circumference of the pressure ring. It is provided with a removal movement tool for removing the wafer by moving the pressure ring to the outside.

Preferably, the inner circumferential portion of the pressing ring is recessed to be in surface contact with the side surface of the wafer, and the upper surface is formed at about half the thickness of the wafer, and the upper surface of the lower electrode has a predetermined spiral angle from the center to the outer circumferential direction. Rotating spiral cooling slots are formed.

The spiral cooling slot is preferably composed of a canyon portion having a narrow narrow vertical cross section, and a cylindrical portion formed in a circular cross section at the lower side of the canyon portion.

Best Mode for Carrying Out the Invention Preferred embodiments of the present invention will now be described based on the accompanying drawings.

3 is a schematic view of a chemical vapor deposition apparatus according to the present invention, as shown, the conventional chemical vapor deposition apparatus is a chamber 21 for depositing a thin film on the upper surface of the wafer (W) is injected into the deposition gas, and An exhaust pipe 22 for discharging the by-product generated by the unreacted deposition gas in the chamber 21, a pump 23 for removing the deposition gas in the chamber 21 and maintaining it at a constant low pressure, and the deposition The flow rate control part 24 which controls the supply amount of gas uniformly, the lower electrode 25 in which the wafer is seated in the chamber 21 and to which the RF power is applied, and the lower electrode 25 correspond to the lower power 25 The upper electrode 26 is applied, and a cold air supply unit 27 connected to one side of the lower electrode 25 to cool the wafer.

The lower electrode 25 is provided with a wafer holding chuck 30 including a side detachment means 40 for reciprocating in the normal direction of the wafer to mount and remove the side of the wafer.

The side detachment means 40 is provided with a pressure ring 41 cut in two with respect to the diameter so as to contact the side of the wafer, and is provided on the outer peripheral side of the pressure ring 41 to apply an elastic force to mount the wafer A member 42 and a pneumatic cylinder or pneumatic motor provided on one inner circumferential side of the pressure ring 41, the movement of the pressure ring 41 to the outside to remove the wafer to remove the wafer (43).

4A is a plan view of the pressing ring, and FIG. 4B is a cross-sectional view illustrating a contact portion between the pressing ring and the wafer. As illustrated, the inner circumferential portion of the pressing ring 41 is recessed to be in surface contact with the side surface of the wafer. An arc recessed portion 41a is formed, and the upper surface of the pressing ring 41 is formed to be located at half (½T) of the wafer thickness T.

FIG. 5A is a plan view of the lower electrode, and a spiral cooling slot 50 is formed on the upper surface of the lower electrode 25 at a predetermined spiral angle θ from the center to the outer circumferential direction, and the spiral cooling slot 50 is formed. As shown in Fig. 5B, the cross section is composed of a canyon portion 51 having a vertical narrow width and a cylindrical portion 52 formed in a circular cross section at the lower side of the canyon portion 51.

Referring to the operation of the wafer holding chuck according to the present invention configured as described above are as follows.

In FIG. 3, when the wafer is loaded into the chamber 21, the side surface of the wafer is mounted by the side detachment means 40 of the wafer holding chuck 30 installed in the lower electrode 25. The vapor deposition gas is supplied into the inside of the cylinder, and a predetermined pressure is maintained by the pump 23.

The pressure ring 41 of the side detachable means 40 presses the side surface of the wafer by the elastic restoring force of the elastic member 42, and an arc recessed portion 41a is formed on the inner circumferential portion of the pressure ring 41. Is formed in surface contact with the side of the wafer. In addition, since the upper surface of the pressing ring 41 is located at half (½T) of the wafer thickness, it is possible to prevent a characteristic change caused by abnormal deposition on the side portion of the wafer, and to prevent foreign matters from occurring, thereby improving the quality of the deposition process. Can be kept uniform.

When the deposition process is completed, a pneumatic cylinder or a pneumatic motor, which is a removal movement tool 43 installed inside the pressure ring 41, is operated to move the pressure ring 41 to the outside to remove the side surface of the wafer.

On the other hand, when the wafer is mounted on the holding chuck 30 and the plasma is generated and the deposition process proceeds, a cooling gas is supplied from the cold air supply unit 27 to the center of the lower electrode 25 to cool the back surface of the wafer. As shown in FIG. 5A, the cooling gas is moved along the groove of the spiral cooling slot 50 that is rotated at a predetermined spiral angle θ in the circumferential direction from the center of the lower electrode 25. Cool the back.

As shown in FIG. 5B, the helical cooling slot 50 includes a valley part 51 having a low pressure P ₁ and a cylindrical part 52 having a high pressure P ₂ so that the cooling gas pressure is higher. It is delivered to the side of the flow direction of the cooling gas, rather than being transferred to the side, so that the back side of the wafer can be effectively cooled. The venturi effect is generated by the cross-sectional shape as described above, and thus, the valley part can be minimized due to the cooling gas pressure. At 51, the flow velocity is increased, so that the temperature of the wafer can be efficiently controlled.

As described above, the wafer holding chuck according to the present invention is electrically connected to the wafer holding chuck by installing a pressure ring, an elastic member, and a side detachment means composed of a stripping tool so as to mount and remove the side surface of the wafer positioned on the lower electrode. Since the static electricity generated by the polarization phenomenon is not used, the wafer is prevented from being damaged by the electric current, and the static elimination process of removing residual charges is eliminated, thereby improving productivity and making the wafer stable by simply forming an electrical configuration. There is an effect that can be mounted and removed.

Claims (5)

And a side detachment means for reciprocating in the normal direction of the wafer positioned at the lower electrode to mount and remove the side of the wafer. The method of claim 1, wherein the side detachable means is a plurality of pressurized ring with respect to the diameter to be in contact with the side of the wafer, an elastic member is provided on the outer peripheral side of the pressing ring to apply an elastic force to mount the wafer; A wafer holding chuck, which is provided on one inner circumference of the pressing ring, and comprises a stripping tool for moving the pressing ring outward to remove the wafer. The wafer holding chuck of claim 2, wherein an inner circumferential portion of the pressing ring is recessed to be in surface contact with a side surface of the wafer, and an upper surface thereof is about half the thickness of the wafer. The wafer holding chuck according to claim 1 or 2, wherein the upper surface of the lower electrode includes a spiral cooling slot that rotates at a predetermined spiral angle from the center to the outer circumferential direction. 5. The wafer holding chuck according to claim 4, wherein the spiral cooling slot comprises a gorge having a narrow narrow vertical cross section and a cylindrical portion formed in a circular cross section under the gorge.