Adhesive bonding and miscellaneous chemical manufacture – Differential fluid etching apparatus – With workpiece support
Reexamination Certificate
2001-01-02
2004-01-13
Mills, Gregory (Department: 1763)
Adhesive bonding and miscellaneous chemical manufacture
Differential fluid etching apparatus
With workpiece support
C156S345510, C156S345520, C118S724000, C118S725000, C118S728000
Reexamination Certificate
active
06676804
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a plasma processing apparatus and a plasma processing method.
BACKGROUND ART
A plasma etching apparatus is utilized during the process of manufacturing a semiconductor device in the prior art. In the processing chamber of the apparatus, an upper electrode and a lower electrode are set facing opposite each other. In the plasma etching apparatus adopting this structure, the processing gas introduced into the processing chamber is raised to plasma when high-frequency power is applied to the lower electrode and the workpiece placed on the lower electrode, such as a semiconductor wafer (hereafter referred to as a “wafer”) becomes etched. In addition, the lower electrode is internally provided with a temperature control mechanism to adjust the wafer temperature. The lower electrode is also provided with a ring body. The ring body is constituted of an inner ring body and an outer ring body. The inner ring body is set so as to encompass the outer edges of the wafer placed on the lower electrode. The outer ring body is set so as to encompass the periphery of the inner ring body.
The inner ring body is constituted of a conductive material. Thus, the external diameter of the wafer can be made to appear electrically large relative to the plasma during the plasma processing. As a result, the plasma is admitted to the entire wafer in an even manner including the outer edges of the wafer as well as the central area. The outer ring body is constituted of an insulating material. Thus, the plasma becomes concentrated on the wafer during the plasma processing so that the plasma can be evenly guided over the entire wafer surface.
However, the conductive inner ring body where intense ion collisions occur, as at the wafer, becomes heated very easily. In addition, the inner ring body is set above the lower electrode unlike the outer ring body which is directly secured to the lower electrode. As a result, since the heat of the inner ring body cannot be fully radiated to the lower electrode in the pressure reduced atmosphere during the processing, the temperature of the inner ring body becomes high. This results in an inconsistent radical concentration in the vicinity of the inner ring body, to reduce the etching rate at the outer edges of the wafer adjacent to the inner ring body. In addition, a discrepancy in the processing is created between the center of the wafer and the outer edges of the wafer and it becomes difficult to achieve uniform processing over the entire wafer surface.
Technologies for processing wafers having a large diameter, e.g., 300 mm, have been proposed in recent years. The processing area at the outer edges of the wafer increases in proportion to the diameter of the wafer. Consequently, the reduction in yield is further exacerbated unless uniform processing is achieved at the outer edges of the wafer, as described above. In addition, in order to improve the productivity of semiconductor element manufacturing, it is necessary to form elements as close to the outer edges of the wafer as possible. However, this technical requirement cannot be satisfied unless uniform processing is achieved at the outer edges of the wafer.
Furthermore, the rate at which ions in the plasma collide with each other at the insulating outer ring body is a lower than the collision rate at the inner ring body. Thus, the temperature of the outer ring body rises more slowly than the temperature at the inner ring body. As a result, when performing continuous processing, the temperature at the outer ring body in particular, is not stable, after the start of processing until a specific number of wafers have been processed. If the temperature at the outer ring body is unstable, the radical concentration at the periphery of the outer ring body, e.g., at the area encompassing the outer edges of the wafer, becomes inconsistent. Consequently, uniform processing is not achieved at the center of the wafer and at the outer edges of the wafer, resulting in difficulty in performing uniform processing over the entire wafer surface. This necessitates processing to be performed on a specific number of dummy wafers until the temperature of the outer ring body becomes stabilized. Thus, the throughput is reduced.
DISCLOSURE OF THE INVENTION
The present invention has been completed by addressing the problems of the prior art discussed above. A first object of the present invention is to provide a new and improved plasma processing apparatus capable of performing uniform processing over the entire surface of a workpiece by generating radicals evenly over the workpiece and the outer edges of the workpiece and a method adopted in this plasma processing apparatus.
A second object of the present invention is to provide a new and improved plasma processing apparatus capable of performing consistent and stable processing on a workpiece immediately after the start of processing and a method adopted in this plasma processing apparatus.
In order to achieve the objects described above, in a first aspect of the present invention, a plasma processing apparatus that performs plasma processing on a workpiece placed on an electrode provided inside a processing chamber comprising a means for temperature control provided at the electrode, a conductive ring body encompassing the periphery of the workpiece placed on the electrode, a first gas supply passage through which a heat transfer gas is supplied to the space between the conductive ring body and the electrode, a means for pressure regulation that regulates the pressure of the heat transfer gas that is supplied so that the temperature of the conductive ring body and the temperature of the workpiece are set roughly equal to each other and a first means for control that controls the means for pressure regulation, is provided.
In this structure, the first means for control adjusts the means for pressure regulation to set the pressure of the heat transfer gas to a specific level. The heat transfer gas, having undergone this adjustment, is then supplied to the space between the conductive ring body and the electrode via the first gas supply passage. The heat transfer gas supplied in this manner increases the thermal conductivity between the conductive ring body and the electrode even in the pressure reduced atmosphere during the processing so that the heat of the conductive ring body can be reliably absorbed by the electrode. Thus, even if the conductive ring body is heated, the temperature of the conductive ring body can be maintained at a specific level. As a result, consistency is achieved in the radical concentration in the vicinity of the outer edges of the workpiece adjacent to the conductive ring body to enable a specific type of processing to be performed at the outer edges of the workpiece. In addition, the pressure of the heat transfer gas can be adjusted as necessary by the means for gas pressure regulation. Consequently, the temperature of the conductive ring body can be set as appropriate for a specific process to be implemented. The means for pressure regulation is controlled so as to roughly equalize the temperature of the conductive ring body with the temperature of the workpiece. This structure achieves consistency in the concentration of radicals distributed around the workpiece and the conductive ring body. As a result, uniform processing is achieved at the center of the workpiece and at the outer edges of the workpiece to realize uniform processing over the entire surface of the workpiece.
Furthermore, it is desirable that the first means for control implement control on the means for pressure regulation based upon temperature information obtained through detection performed by temperature sensors that measure the temperature of the conductive ring body and the temperature of the workpiece. By adopting this structure, the temperature of the conductive ring body can be set at a specific level in conformance to the temperature of the workpiece, which changes continually during the processing.
In addition, one or a plurality of se
Higuchi Kimihiro
Ishihara Hiroyuki
Koshimizu Chishio
Maruyama Koji
Finnegan Henderson Farabow Garrett & Dunner LLP
Hassanzadeh P.
Mills Gregory
Tokyo Electron AT Limited
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