TW201332013A - Focus ring for reducing polymer at the back of wafer - Google Patents

Abstract

This invention discloses a focus ring for reducing polymer at the back of a wafer. The focus ring includes an internal ring and an external ring. The internal ring surface is plasma-corrosion resistant metal oxide, which guarantees that the polymer at the back of the wafer is silicon-free for easy cleaning. In the mean time, metal oxide material is only applied to the internal ring so that the metal oxide material will not contact plasma directly, and this prevents the pollution of metal oxide particles in a plasma processing chamber under plasma bombing. The focus ring can be made of semiconductor material as well as insulating material, has simple structure, and can greatly reduce polymer at the back of a wafer.

Description

A focus ring for reducing polymer formation on the back side of a wafer

The present invention relates to the field of manufacturing semiconductor devices, and more particularly to the technical field of reducing the polymer on the back side of a wafer.

When the semiconductor wafer is etched, the wafer is placed on the pedestal of the plasma etch chamber, and a periphery of the susceptor is generally disposed around the susceptor to adjust the electric field strength in the plasma etch chamber to ensure the center area and the edge of the wafer. Uniformity of area etching. A narrow gap is formed between the focus ring and the wafer. During etching, the plasma etching chamber applies energy to the etching reaction gas (composed of one or more gases) to excite the gas to form a plasma, and the plasma in the reaction gas. The chemical reaction with the material on the surface of the focus ring causes the resulting polymer to deposit on the exposed edge portions of the back side of the wafer, causing contamination. There are many materials that can be used to make the focus ring. When the focus ring is an insulating material such as quartz or alumina, the portion of the focus ring exposed to the plasma is corroded by the plasma to form metal-containing particles, which causes serious damage to the wafer to be processed. Pollution; when the focus ring is a semiconductor-containing material, such as tantalum carbide, tantalum, etc., the plasma reacts with helium to form a germanium-containing polymer. Since the germanium-containing polymer is difficult to remove, it is concentrated on the back side of the wafer, which may become a follow-up. The source of pollution in semiconductor processes.

In order to solve the problems of the prior art, the present invention provides a focus ring for reducing a polymer generated on the back surface of a wafer, which surrounds a wafer disposed in a plasma etching chamber and an outer peripheral side of a susceptor supporting the wafer, the focus ring The utility model comprises an inner ring ring and an outer ring ring extending below the edge of the back surface of the wafer, the surface of the inner ring ring being plasma corrosion resistant metal An oxide, the outer ring surface being a semiconductor material.

The material of the focus ring body is tantalum carbide, and the plasma corrosion resistant metal oxide is one or more of antimony trioxide, aluminum oxide and lithium trifluoride coated on the main body of the focus ring. Kind.

The material of the focus ring body is antimony trioxide, and the semiconductor material coated on the surface of the outer ring ring is tantalum carbide.

The material of the focus ring body is aluminum oxide, and the semiconductor material coated on the surface of the outer ring ring is ruthenium.

The focus ring comprises two materials, the inner ring material is antimony trioxide, and the outer ring material is tantalum carbide.

The focus ring comprises two materials, the inner ring material is aluminum oxide, and the outer ring material is ruthenium.

The process of applying the plasma corrosion resistant metal oxide is a chemical vapor deposition or spray coating process.

The inner ring surface material of the focus ring of the present invention adopts a plasma corrosion-resistant metal oxide, and the surface material of the outer ring ring is made of a semiconductor material, thereby ensuring that the polymer formed on the back surface of the wafer is free of defects and easy to clean, and at the same time, Only the metal oxide material is used in the inner ring, so that the metal oxide material does not directly contact with the plasma, which ensures that there is no metal oxide particle contamination in the plasma processing chamber under plasma bombardment. The focus ring body of the present invention can be either a semiconductor material or an insulating material, has a simple structure, and can significantly reduce the formation of a polymer on the back side of the wafer.

Other features, objects, and advantages of the invention will be apparent from the description of the accompanying drawings.

100‧‧‧plasma etching chamber

1‧‧‧ wafer

2‧‧‧ lower electrode

3‧‧‧Support ring

4‧‧‧ Focus ring

41‧‧‧ inner ring

42‧‧‧ outer ring

5‧‧‧Edge ring

110‧‧‧Responsive gas source

10‧‧‧Upper electrode

1 is a schematic structural view of a plasma etching chamber to which a focus ring according to the present invention is applied; FIG. 2 is a schematic structural view of a focus ring according to the present invention.

As shown in FIG. 1-2, the present invention specifically discloses a focus ring for reducing the formation of a polymer on the back surface of the wafer. In the plasma etching chamber 100, there are an upper electrode 10 and a lower electrode 2, and the upper electrode 10 is connected to the reaction gas source 110. It can be used as a gas injection device at the same time. The lower electrode 2 simultaneously serves as a susceptor in the plasma etching chamber to support the wafer 1 above it.

A focus ring 4 is disposed around the periphery of the wafer 1 and the lower electrode 2, and a narrow gap is formed between the upper surface of the focus ring 4 and the lower surface of the wafer 1; the lower surface is seated on a support ring 3, and the focus ring 4 includes Ring 41 and outer ring 42, inner ring 41 extends below the edge of the back side of the wafer, outer ring 42 is surrounded by an edge ring 5, edge ring 5 is adjacent to the plasma reaction chamber wall, inner ring 41 and outer The ring 42 may be integral or independent of each other. In the present embodiment, the inner ring 41 and the outer ring 42 are integrated.

In the present invention, the material of the body of the focus ring 4 may be an insulating material such as quartz, ceramics or the like, or may be a semiconductor material such as tantalum, tantalum carbide or the like. As a commonly used material for making a focus ring, tantalum carbide is generally obtained by chemical vapor deposition. During etching, an energy is applied to the etching reaction gas (composed of one or more gases) in the plasma etching chamber 100 to excite the gas to form a plasma. The plasma in the reaction gas and the surface of the inner ring 41 of the focus ring 4 are chemically reacted, and the generated ruthenium-containing polymer is deposited on the exposed portion of the back surface of the wafer. Since the ruthenium-containing polymer is difficult to remove, it will More and more polymer is formed on the back side of the wafer 1, causing contamination and affecting the subsequent reaction process. In order to prevent the plasma from reacting with the surface of the inner ring 41, the surface of the inner ring 41 is coated with a plasma corrosion-resistant metal oxide, which may be one or more of cerium oxide, aluminum oxide and lithium fluoride. Kind. The metal oxide coating process employed in this embodiment is a spray coating process.

The invention may also be made of an insulating material to make a focus ring, such as yttrium oxide, aluminum oxide, Lithium fluoride or the like, since the outer ring 42 of the focus ring made of the above metal oxide is exposed to the plasma, the metal-containing particles formed by the plasma bombardment are present in the plasma processing chamber, causing contamination of the wafer to be processed. A metal-free material such as tantalum carbide or niobium is coated on the surface of the outer ring 42 to ensure normal reaction. The process of coating tantalum carbide or niobium is a chemical vapor deposition process.

Embodiment 2: The inner ring 41 and the outer ring 42 of the focus ring 4 of the present embodiment are independent of each other and are made of different materials. The inner ring 41 is made of a metal oxide material resistant to plasma corrosion, such as oxidation. One or more of ruthenium, aluminum oxide and lithium fluoride are used in the present embodiment; the outer ring 42 is made of a semiconductor material such as tantalum, tantalum carbide or the like. In this embodiment, tantalum is used as the material of the outer ring 42. Other technical features of this embodiment are the same as those of the above embodiment.

Although the invention has been disclosed above in the preferred embodiments, the invention is not limited thereto. Any changes and modifications may be made by those skilled in the art without departing from the spirit and scope of the invention, and the scope of the invention should be determined by the scope defined by the appended claims.

1‧‧‧ wafer

2‧‧‧ lower electrode

3‧‧‧Support ring

41‧‧‧ inner ring

42‧‧‧ outer ring

5‧‧‧Edge ring

Claims (7)

A focus ring for reducing a polymer generated on a back surface of a wafer, the focus ring surrounding a wafer disposed in a plasma etch chamber and an outer peripheral side of a susceptor supporting the wafer, the focus ring including an inner ring and a An outer ring, the inner ring extends below an edge of the back side of the wafer, wherein the surface of the inner ring is a plasma corrosion resistant metal oxide, and the outer ring surface is a semiconductor material. A focus ring for reducing a polymer generated on a back side of a wafer according to claim 1, wherein the focus ring body material is tantalum carbide, and the plasma corrosion resistant metal oxide is coated on the focus ring. One or more of antimony trioxide, aluminum oxide, and lithium trifluoride on the main body. A focus ring for reducing polymer generated on the back side of a wafer according to claim 1, wherein the focus ring body material is antimony trioxide, and the semiconductor material coated on the outer ring surface is tantalum carbide. A focus ring for reducing polymer generated on the back side of a wafer according to claim 1, wherein the focus ring body material is aluminum oxide, and the semiconductor material coated on the surface of the outer ring ring is germanium. A focus ring for reducing polymer generated on the back side of a wafer according to claim 1, wherein the focus ring comprises two materials, the inner ring material is antimony trioxide, and the outer ring material is carbonized. Hey. A focus ring for reducing polymer generated on the back side of a wafer according to claim 1, wherein the focus ring comprises two materials, the inner ring material is aluminum oxide, and the outer ring material is It is expected to be 矽. A method of reducing a focus ring for forming a polymer on a back side of a wafer according to claim 2, wherein the process of coating the plasma corrosion resistant metal oxide is a chemical vapor deposition or a spray coating process.