Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With microwave gas energizing means
Reexamination Certificate
2000-11-14
2001-08-21
Mills, Gregory (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With microwave gas energizing means
C118S7230AN
Reexamination Certificate
active
06277237
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to semiconductor fabrication and, more particularly, to a chamber liner for use in semiconductor process chambers.
In semiconductor fabrication, plasma etching is commonly used to etch conductive and dielectric materials. One of the problems with plasma etching is that a film builds up on the wall of the process chamber over the course of time as multiple wafers are processed in the chamber. This film build-up may cause problems in either of two ways. First, the film may flake off the wall and introduce particulates into the chamber. As feature sizes in integrated circuit devices continue to decrease, the degree to which particulates can be tolerated during processing is rapidly declining. Therefore, it is becoming increasingly more important to avoid particulates during processing. Second, the film may alter the RF ground path and thereby affect the results obtained on the wafer. The occurrence of either of these conditions is undesirable and signals the need to subject the process chamber to a wet cleaning operation in which the wall of the chamber is physically scrubbed to remove the film build-up.
Wet cleaning of process chambers is not preferred in commercial semiconductor fabrication because it requires that a process module be taken off-line and thereby reduces throughput. In an effort to avoid the need for wet cleaning, some process chambers have been provided with a liner for protecting the wall of the chamber. The use of a liner is advantageous because the liner can be easily replaced with minimal downtime when film build-up occurs thereon.
Cylindrical liners currently used in process chambers, however, suffer from at least two major drawbacks. The first drawback is that such a liner, the entirety of which is located in a vacuum, lacks an adequate thermal connection because thermal transfer in a vacuum is poor. As a result, the temperature of the liner fluctuates dramatically when the RF power is cycled on and off. This temperature fluctuation causes undesirable variations in the processing of the wafer. The second drawback is that it is difficult to make an electrical connection to the liner in the vacuum that provides a satisfactory RF ground return path. The materials commonly used for this purpose, e.g., stainless steel screws, copper strapping, and beryllium copper fingers, produce contaminants on the wafer because they are not compatible with the reactive materials within the chamber, i.e., the plasma chemistry.
In view of the foregoing, there is a need for a chamber liner for a semiconductor process chamber that provides thermal stability, an adequate RF ground return path, and serviceability with minimal downtime.
SUMMARY OF THE INVENTION
Broadly speaking, the invention fills this need by providing an upper chamber liner that is configured to provide thermal stability, a gridded design that serves as a RF ground return path, and easy removal for cleaning. The invention also provides a process chamber for use in semiconductor fabrication that includes the upper chamber liner of the invention.
In one aspect of the invention, a process chamber for use in semiconductor fabrication is provided. The process chamber includes a housing having an inner surface defining a chamber in which a vacuum is drawn during processing of a semiconductor wafer. The process chamber further includes an upper chamber liner having a plasma confinement shield with a plurality of apertures. An outer sidewall extends upwardly from the plasma confinement shield. An outer flange extends outwardly from the outer sidewall such that the outer flange extends beyond the chamber and into a space at atmospheric pressure. The upper chamber liner preferably further includes an inner sidewall that extends upwardly from the plasma confinement shield. The plasma confinement shield, the inner and outer sidewalls, and the outer flange are preferably integral with one another. The process chamber still further includes a lower chamber liner that protects the inner surface of the housing that is not covered by the upper chamber liner.
In one preferred embodiment, the plasma confinement shield has an annular configuration that defines an inner circumference and an outer circumference. In this preferred embodiment, the outer and inner sidewalls are cylindrical. The cylindrical outer sidewall extends upwardly from the outer circumference for a first distance and is preferably substantially perpendicular to the plasma confinement shield. The cylindrical inner sidewall extends upwardly from the inner circumference for a second distance, which is shorter than the first distance, and is preferably substantially perpendicular to the plasma confinement shield. If desired, the cylindrical inner sidewall may include an inner flange that extends inwardly in a direction substantially opposite to the direction in which the outer flange extends.
The upper chamber liner is preferably mounted in the process chamber such that a first RF gasket is in contact with the upper surface of the outer flange and a second RF gasket is in contact with a lower surface of the outer flange. When the upper chamber liner is formed of anodized aluminum, the first and second RF gaskets are in contact with portions of the upper and lower surfaces of the outer flange, respectively, that are substantially free of anodization.
In accordance with another aspect of the invention, a chamber liner for use in a process chamber used in semiconductor fabrication is provided. The chamber liner includes a plasma confinement shield having a plurality of apertures. An outer sidewall, which is preferably integral with the plasma confinement shield, extends upwardly from the plasma confinement shield. An outer flange, which is preferably integral with the outer sidewall, extends outwardly from the outer sidewall. The outer flange is configured to extend beyond an internal vacuum region of a process chamber and into a space at atmospheric pressure. The chamber liner preferably further includes an inner sidewall that extends upwardly from the plasma confinement shield. The inner sidewall is preferably integral with the plasma confinement shield.
In one preferred embodiment, the plasma confinement shield has an annular configuration that defines an inner circumference and an outer circumference. In this preferred embodiment, the outer and inner sidewalls are cylindrical. The cylindrical outer sidewall extends upwardly from the outer circumference for a first distance and is preferably substantially perpendicular to the plasma confinement shield. The cylindrical inner sidewall extends upwardly from the inner circumference for a second distance, which is shorter than the first distance, and is preferably substantially perpendicular to the plasma confinement shield. If desired, the cylindrical inner sidewall may include an inner flange that extends inwardly in a direction substantially opposite to the direction in which the outer flange extends.
The chamber liner is preferably formed of anodized aluminum. To enable the chamber liner to be electrically grounded to the housing of a process chamber, the upper and lower surfaces of the outer flange are provided with areas for receiving RF gaskets that are substantially free of anodization.
The chamber liner, i.e., the upper chamber liner, of the invention provides a number of significant technical advantages. Because the outer flange extends beyond the chamber and into the atmosphere, the chamber liner can be electrically grounded to the housing of the process chamber using known RF gasket materials without producing contaminants on the wafer. The outer flange also provides the chamber liner with thermal stability by increasing the thermal conductivity of the liner. This minimizes the fluctuation in temperature that occurs in the chamber liner when the RF power is cycled on and off. Another advantage is that continuous RF gaskets can be used to electrically connect the outer flange to the housing of the process chamber. The use of continuous RF gask
Barnes Michael
Denty, Jr. William M.
Schoepp Alan M.
Alejandro Luz L.
Lam Research Corporation
Martine & Penilla LLP
Mills Gregory
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