TWI618183B - Plasma processing device and electrostatic chuck - Google Patents

Abstract

The invention discloses an electrostatic chuck, which comprises an insulating layer embedded with an electrode for carrying a semiconductor wafer. The insulating layer has a main body portion and an annular flange extending horizontally outward along a side wall of the main body portion; a base is located on the insulation. Under the layer; a bonding layer is located between the insulating layer and the base for bonding the insulating layer and the base, wherein the diameter of the annular flange is larger than the diameter of the outer periphery of the bonding layer And a diameter larger than the top surface of the base; and an edge ring located above the annular flange, a gap between an inner wall of the edge ring and an outer peripheral edge of the main body portion, and an annular flange portion overlapping. The invention can effectively prevent the electrostatic chuck from being damaged by the plasma bombardment.

Description

Plasma processing device and electrostatic chuck

The invention relates to semiconductor processing equipment, in particular to an electrostatic chuck and a plasma processing device having the same.

In recent years, with the development of semiconductor manufacturing processes, the integration and performance requirements of components have become higher and higher. Plasma Technology is playing a pivotal role in the field of semiconductor manufacturing. Plasma technology is used in many semiconductor processes, such as deposition processes (such as chemical vapor deposition), etching processes (such as dry etching), and so on. Generally speaking, in these processes, an electrostatic chuck (ESC) is generally used to fix, support, and transport semiconductor wafers, so as to prevent the wafers from moving or dislocation during the process. An electrostatic chuck is usually set at the bottom of the chamber of the plasma processing device, and is connected to the RF power source as the lower electrode. A radio frequency electric field is formed between the upper electrode at the top of the chamber and the lower electrode, so that the electrons accelerated by the electric field can communicate with each other. The etching gas molecules entering the processing chamber are ionized and collide, and the plasma generated by the process gas reacts with the wafer.

The electrostatic chuck uses electrostatic attraction to fix semiconductor wafers. Compared with mechanical chucks and vacuum chucks, it has the advantages of reducing wafer damage caused by pressure, collision, etc., increasing the area where wafers can be effectively processed, and reducing wafer surface corrosion. Particles are deposited, the wafer and chuck can perform better heat conduction, and can work in a vacuum environment. As shown in FIG. 1 a, the electrostatic chuck in the prior art includes an insulating layer 10, a base 30, and an edge ring 40. DC electrode layer 11 buried Hidden in the insulating layer 10, the electrostatic chuck uses the Coulomb force or the Johnsen-Rahbek force generated between the DC electrode layer 11 and the semiconductor wafer, so that the wafer is firmly adsorbed on the electrostatic chuck. To achieve the purpose of fixing the wafer. The base 30 is used to support the insulating layer. The edge ring 40 surrounds the semiconductor wafer to provide a relatively closed environment around the wafer. The insulating layer is generally made of ceramic materials, the base is generally made of metal such as aluminum, and the surface of the base is covered with a protective film of chlorine dioxide, for example. The edge ring 40 may be made of various materials such as alumina or other types of ceramics. The insulating layer 10 and the base 30 are bonded by an adhesive 20, and the adhesive 20 (the reference numeral 20 in FIG. 1 is a little crooked, and the form of drawing the adhesive 20 as a material layer is more in line with the industry). The common practice) is generally silicon glue, and the insulating layer 10, the base 30 and the adhesive 20 have the same outer diameter.

However, when plasma processing is performed, especially during high temperature processing, the electrostatic chuck is thermally expanded. Due to the assembly differences and the thermal expansion coefficients of different materials of the insulating layer 10, the adhesive 20 and the base 30, it causes The degree of thermal expansion is also different; coupled with the shearing force generated by the base 30 to the adhesive 20 during thermal expansion, the adhesive 20 will expand beyond the insulating layer 10 and will no longer be protected by the insulating layer after expansion, as shown in Figure 1b . In this way, the adhesive 2 is easily susceptible to the erosion of the plasma. Since the adhesive 20 is usually doped with metal ions, arcing is easy to occur under the action of a strong electric field, and more serious will directly cause static electricity. Damage to the chuck is discarded.

In order to solve this problem, in the prior art, the outer diameter of the adhesive 20 is reduced so that it does not exceed the insulation layer after thermal expansion to avoid the occurrence of arc discharge. However, this method is difficult to control the reduction of the outer diameter of the adhesive, and the manufacturing process is high.

The main purpose of the present invention is to overcome the defects of the prior art and provide an electrostatic chuck which is not easily damaged by plasma.

In order to achieve the above object, the present invention provides an electrostatic chuck, comprising: an insulating layer embedded with an electrode for carrying a semiconductor wafer, the insulating layer having a main body portion and an annular flange extending horizontally outward along a side wall of the main body portion; a base Is located below the insulating layer; a bonding layer is located between the insulating layer and the base for bonding the insulating layer and the base, wherein the diameter of the annular flange is larger than the bonding The diameter of the outer peripheral edge of the layer is larger than the diameter of the top surface of the base; and an edge ring is located above the annular flange, and there is a gap between the inner wall of the edge ring and the outer peripheral edge of the main body, and The annular flanges partially overlap.

Preferably, the cross-sectional shape of the annular flange is rectangular or L-shaped.

Preferably, the bonding layer and the insulating layer are disposed concentrically, and a diameter of the bonding layer is smaller than or equal to a diameter of the main body portion.

Preferably, the annular flange extends 0.5 to 3 mm beyond the outer peripheral edge of the main body portion.

Preferably, the thickness of the annular flange is greater than or equal to one tenth of the thickness of the insulating layer.

Preferably, the edge ring is located at least 0.1 mm above the upper surface of the annular flange.

Preferably, a gap between an inner wall of the edge ring and an outer peripheral edge of the main body portion is 0.1 to 2 mm.

Preferably, an outer peripheral edge of the bonding layer is surrounded by an insulating protection member, and the annular flange extends beyond the outer peripheral edge of the insulating protection member.

Preferably, the material of the insulating layer is ceramic, and the material of the bonding layer is silicon rubber.

Preferably, the insulation protection member is epoxy resin.

According to another aspect of the present invention, the present invention also provides a plasma processing apparatus having the above-mentioned electrostatic chuck.

The beneficial effect of the present invention is that the ring flange structure of the insulating layer of the electrostatic chuck makes the bonding layer under the insulation layer always under the protection of the ring flange, even if thermal expansion occurs, it will not be exposed and will be exposed to plasma bombardment and cause arc discharge. The electrostatic chuck is even destroyed. Therefore, the invention can effectively improve the service life of the electrostatic chuck.

1‧‧‧ Plasma treatment device

10‧‧‧ Insulation

11‧‧‧DC electrode layer

12‧‧‧ main body

13‧‧‧ annular flange

20‧‧‧Combination layer

21‧‧‧Insulation protection

30‧‧‧ base

40‧‧‧Edge ring

2‧‧‧DC DC voltage source

3‧‧‧RF RF Power Source

P‧‧‧ Plasma

Fig. 1a is a schematic diagram of an electrostatic chuck in the prior art; Fig. 1b is a schematic diagram of an electrostatic chuck in the prior art after thermal expansion; Fig. 2 is a schematic diagram of a plasma processing apparatus according to an embodiment of the present invention; A schematic diagram of a chuck; FIG. 3b is a schematic diagram of an electrostatic chuck after thermal expansion according to an embodiment of the present invention; and FIG. 4 is a schematic diagram of an electrostatic chuck according to another embodiment of the present invention.

In order to make the content of the present invention more clear and easy to understand, the content of the present invention is further described below with reference to the accompanying drawings of the description. Of course, the present invention is not limited to this specific embodiment, and general substitutions well known to those skilled in the art are also covered by the protection scope of the present invention.

FIG. 2 shows a plasma processing apparatus 1 using an electrostatic chuck according to an embodiment of the present invention. It should be understood that the plasma processing apparatus 1 is merely exemplary and may include fewer or more constituent elements, or the arrangement of the constituent elements may be different from that shown in FIG. 2.

The plasma processing apparatus 1 includes an electrostatic chuck disposed in a chamber. A semiconductor wafer (not shown) is placed on the surface of the electrostatic chuck. The process gas source (not shown) supplies the chamber with the process gas required for the plasma processing process. An electrode 11 is embedded in the electrostatic chuck. RF RF power The rate source 3 is applied to the electrode 11 and generates a large electric field inside the chamber. The electric field excites the electrons in the chamber, causing them to collide with the gas molecules of the process gas to generate plasma P. The DC DC voltage source 2 applies a high-voltage DC power source to the electrode 11 to generate polarized charges on the surface of the electrostatic chuck, and further generates polarized charges of opposite polarities at corresponding positions on the surface of the semiconductor wafer. Coulomb force or Jensen generated between. Johnsen-Rahbek forces the wafer to be firmly attached to the electrostatic chuck. After the plasma process is completed, the RF power source 3 is turned off, and a reverse direct voltage is applied to the electrode 11 through the DC direct voltage source 2 to release the semiconductor wafer from the electrostatic chuck.

3a and 3b are schematic diagrams of an electrostatic chuck according to an embodiment of the present invention. Referring to FIG. 3 a, the electrostatic chuck includes an insulating layer 10, a base 30 and an edge ring 40. The insulating layer 10 and the base 30 are bonded by a bonding layer 20. The semiconductor wafer is placed on the upper surface of the insulating layer 10, and the shape of the insulating layer 10 conforms to the wafer, and is generally circular. The insulating layer 10, the bonding layer 20, the base 30 and the edge ring 40 are disposed concentrically. The electrode 11 is embedded in the insulating layer 10, and an electrostatic force is generated between the semiconductor wafer and the insulating layer by applying a DC power source, so that the wafer is firmly adsorbed on the electrostatic chuck. The insulating layer usually further includes a heating element, which is applied to the heating element by an AC alternating current power source to control the surface temperature of the wafer. The insulating layer 10 is generally made of a ceramic material with high resistivity, high thermal conductivity, and low RF loss. It should be understood that the ceramic material may also be doped with materials such as silicon carbide, aluminum nitride, or aluminum oxide. The base 30 is used to support the insulation layer, and is generally made of a metal material, which is beneficial to the feeding of radio frequency energy. The surface of the base 30 is coated with a protective layer such as alumina. The insulating layer 10 and the base 30 are bonded through a bonding layer 20. The material of the bonding layer 20 may be a silicon adhesive.

In the present invention, the insulating layer 10 includes a main body portion 12 and an annular flange 13 extending horizontally outward along the side wall of the main body portion 12. The annular flange 13 is formed on the lower surface of the electrostatic chuck. As shown in FIG. 3b, the diameter of the annular flange 13 is larger than the diameter of the outer periphery of the bonding layer 20 and larger than the diameter of the top surface of the base 30, so that the diameter of the bonding layer 20 after thermal expansion is still smaller than that of the annular flange. The outer diameter of 13 means that the thermal expansion of the bonding layer 20 does not exceed the outer periphery of the annular flange 13, Therefore, the annular flange 13 can protect the bonding layer 20 from being exposed. The cross-sectional shape of the annular flange 13 may be rectangular. In another embodiment of the present invention, the annular flange 13 may also have a downwardly extending protrusion. The cross-sectional shape of the annular flange 13 is L-shaped, which is advantageous in that it can further shield the sidewall of the bonding layer 20. Of course, the cross section of the annular flange may have other shapes, and the present invention is not limited thereto. Preferably, the diameter of the bonding layer 20 is slightly smaller than or equal to the diameter of the main body portion 12 of the insulating layer, and the annular flange 13 extends beyond the outer peripheral edge of the main body portion 12. In actual work, the specifications of the semiconductor wafer are, for example, 200mm, 300mm, or 450mm or other dimensions. The shape and size of the insulating layer 10 are consistent with the wafer. The annular flange 13 extends 0.5 to 3 mm from the outer periphery of the main body 12 to achieve shielding bonding. Purpose of layer 20. In addition, the thickness of the annular flange 13 is not less than one tenth of the entire thickness of the insulating layer 10. When the plasma chuck undergoes thermal expansion, although the thermal expansion coefficient of each part of the electrostatic chuck is different, the degree of expansion of the bonding layer 20 is greater than that of the insulating layer 10, but the annular flange of the insulating layer 13. The bonding layer 20 is still under the protection of the annular flange 13 and is not exposed. Therefore, the plasma bombardment will not reach the bonding layer 20, thereby effectively preventing the occurrence of arc discharge. In addition, it is worth noting that the processing steps of the electrostatic chuck of the present invention are not different from the prior art, they all place the insulating layer after coating the bonding layer 20 on the upper surface of the base, and the radial dimension of the bonding layer 20 is not required. Reduced control. For the case where the diameter of the bonding layer 20 is slightly smaller than the insulating layer, it is only necessary to scrape off the thinner outer layer of the bonding layer 20 after coating the bonding layer 20, and the process steps are simple and convenient.

Please continue to refer to FIG. 3a, the edge ring 40 is disposed above the annular flange 13 of the insulating layer. The material of the edge ring 40 is non-metal. It surrounds the semiconductor wafer and is used to provide a relatively closed environment around the wafer to improve the uniformity of the plasma on the surface of the wafer. The impact of the pulp processing process causes pollution. There is a gap between the inner wall of the edge ring 40 and the outer peripheral edge of the insulating layer main body 12, and this gap can be used to prevent possible damage between the edge ring 40 and the semiconductor wafer due to different thermal expansion coefficients; meanwhile, the edge ring 40 and the annular protrusion The edge 13 has a partial overlap in the vertical direction. As shown in Figure 3b, when static electricity occurs When the chuck is thermally expanded, the bonding layer 20 is still under the protection of the annular flange 13 and the overlapping portion of the edge ring 40 and the annular flange 13 further prevents the plasma from reaching the bonding layer 20 from outside the annular flange 13 to effectively avoid The occurrence of arc discharge. In a preferred embodiment, the edge ring 40 is located at least 0.1 mm above the upper surface of the annular flange 13, and the gap between the inner wall of the edge ring and the outer peripheral edge of the main body portion is 0.1 to 2 mm.

Please continue to refer to FIG. 4, which is a schematic diagram of an electrostatic chuck according to another embodiment of the present invention. The electrostatic chuck includes an insulating layer 10 and a base 30 on which electrodes 11 are embedded, and the insulating layer 10 and the base 30 are bonded by a bonding layer 20. The material of the bonding layer 20 may be a silicon adhesive. The outer peripheral edge of the bonding layer 20 is also filled with a thin layer of insulating protection 21 for sealing the exposed sidewall of the bonding layer 20. The material of the insulating shield 21 is, for example, epoxy resin. When the plasma reaction is performed and the electrostatic chuck is thermally expanded, the bonding layer 20 is still protected by the annular flange 13. Therefore, the plasma bombardment does not reach the bonding layer 20. In addition, the insulation protection member 21 further forms an additional sealing layer, which further prevents the bonding layer 20 from being exposed to the plasma environment. Preferably, the annular flange 13 further extends beyond the outer peripheral edge of the insulating protection member 21, so that both the bonding layer 20 and the insulating protective member 21 do not exceed the outer peripheral edge of the annular flange 13 and are covered by the annular flange 13 after thermal expansion. In addition, the edge ring 40 is provided above the upper surface of the ring-shaped flange 13 of the insulating layer, and there is a gap between the inner wall of the edge ring 40 and the outer peripheral edge of the insulating-layer main body portion 12 and partially overlaps the ring-shaped flange 13. Since the arrangement of the edge ring 40 is similar to that of the first embodiment of the present invention, details are not described herein.

In summary, in the present invention, an insulating layer having a ring-shaped flange structure is used in the electrostatic chuck, so that during the plasma processing process, even if the electrostatic chuck undergoes thermal expansion, the bonding layer bonding the insulating layer and the base is still It can avoid the reach of plasma and avoid arc discharge caused by the bombardment of plasma. Therefore, the present invention improves the defect that the adhesive layer is exposed due to mismatched thermal expansion in the prior art, which causes an arc discharge, which causes the electrostatic chuck to be damaged and scrapped, and effectively improves the service life of the electrostatic chuck.

Although the present invention has been disclosed above with preferred embodiments, many of the embodiments described are only For the convenience of description, examples are not used to limit the present invention. Those skilled in the art can make several changes and modifications without departing from the spirit and scope of the present invention. The scope of protection claimed by the present invention should be defined by the claims. Said prevail.

10‧‧‧ Insulation

11‧‧‧DC electrode layer

12‧‧‧ main body

13‧‧‧ annular flange

20‧‧‧Combination layer

30‧‧‧ base

40‧‧‧Edge ring

Claims (9)

An electrostatic chuck for a plasma processing device includes: an insulating layer embedded with a DC electrode for carrying a semiconductor wafer, the insulating layer having a main body portion and an annular flange extending horizontally outward along a side wall of the main body portion; a base Is located below the insulating layer; a bonding layer is located between the insulating layer and the base for bonding the insulating layer and the base, wherein the diameter of the annular flange is larger than the bonding The diameter of the layer is greater than the diameter of the top surface of the base; and an edge ring located at least 0.1 mm above the upper surface of the annular flange, with a gap between the inner wall of the edge ring and the outer peripheral edge of the main body portion, And it has a partial overlap with the annular flange in a vertical direction, wherein an outer peripheral edge of the bonding layer is surrounded by an insulation protection member, and the annular flange exceeds the outer peripheral edge of the insulation protection member. The electrostatic chuck according to claim 1, wherein a cross-sectional shape of the annular flange is rectangular or L-shaped. The electrostatic chuck according to claim 2, wherein the bonding layer and the insulating layer are disposed concentrically and a diameter of the bonding layer is smaller than or equal to a diameter of the main body portion. The electrostatic chuck according to claim 3, wherein the annular flange extends 0.5 to 3 mm beyond the outer peripheral edge of the main body portion. The electrostatic chuck according to claim 1, wherein the thickness of the annular flange is greater than or equal to one tenth of the thickness of the insulating layer. The electrostatic chuck according to claim 1, wherein a gap between an inner wall of the edge ring and an outer peripheral edge of the main body portion is 0.1 to 2 mm. The electrostatic chuck according to claim 1, wherein a material of the insulating layer is ceramic, and a material of the bonding layer is silicone. The electrostatic chuck according to claim 1, wherein the insulating protection member is epoxy resin. A plasma processing device has a plasma processing chamber and includes the electrostatic chuck described in claim 1-8.