Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
1999-12-30
2002-04-02
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C156S345420
Reexamination Certificate
active
06363882
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to apparatus and methods for processing substrates such as semiconductor substrates for use in IC fabrication or panels (e.g., glass, plastic, or the like) for use in flat panel display applications. More particularly, the present invention relates to methods and apparatuses that are capable of processing substrates with a high degree of processing uniformity across the substrate surface.
Over the years, plasma processing systems utilizing inductively coupled plasma sources, electron cyclotron resonance (ECR) sources, capacitive sources, and the like, have been introduced and employed to various degrees to process semiconductor substrates and display panels. During the manufacture of these products, multiple deposition and/or etching steps may be employed. During deposition, materials are deposited onto a substrate surface (such as the surface of a glass panel or a wafer). For example, deposited layers such as various forms of silicon, silicon dioxide, silicon nitride, metals and the like may be formed on the surface of the substrate. During etching, materials are selectively removed from predefined areas on the substrate surface. For example, etched features such as vias, contacts, or trenches may be formed in the layers of the substrate.
Referring to
FIG. 1
, a conventional plasma processing system
10
is shown. In order to process a substrate, a substrate
12
is placed on a substrate pedestal
14
inside a process chamber
16
and a process gas is fed into the process chamber
16
. Also, energy is supplied to the process gas to ignite a plasma
18
inside the process chamber
16
. After the plasma is ignited, it is sustained with additional energy, which may be coupled to the plasma in various well-known ways, e.g., capacitively, inductively, through microwave, and the like. The plasma is then employed in the processing task, e.g., to selectively etch or deposit a film on the substrate
12
. In most situations, a sheath voltage
20
is formed proximate the substrate surface to accelerate the ions of the plasma towards the substrate
12
where they, possibly in combination with other reactants, activate the processing reaction. The sheath voltage is associated with an electrical potential produced between the substrate pedestal
14
and the plasma
18
.
Unfortunately, however, the electrical coupling between the substrate pedestal
14
and the plasma
18
tends to be non-uniform, which as a result causes variations in the process performance across the surface of the substrate
12
. In particular, the center of the substrate tends to be processed differently than the edge of the substrate, and therefore the yield between the center and edge differ. Accordingly, the edge of the substrate is not generally used to create IC's, which as a result translates into higher costs for the manufacturer. Furthermore, the demand for larger substrates has made it increasingly important to improve process uniformity at the edge of the substrate.
In view of the foregoing, there are desired improved methods and apparatuses for increasing process uniformity at the surface of the substrate.
SUMMARY OF THE INVENTION
The invention relates, in one embodiment, to a plasma processing system for processing a substrate. The plasma processing system includes a process chamber within which a plasma is both ignited and sustained for processing. The process chamber has an upper end and a lower end. The plasma processing system further includes an electrode disposed at the lower end of the process chamber. The electrode is configured for generating an electric field inside the process chamber. The plasma processing system also includes a component for controlling an impedance between said electrode and said plasma, said impedance being arranged to affect said electric field to improve processing uniformity across the surface of said substrate.
The invention relates, in another embodiment, to a plasma processing system for processing a substrate. The plasma processing system includes a process chamber within which a plasma is both ignited and sustained for processing. The plasma processing system further includes an electrode disposed inside the process chamber. The electrode is configured for generating an electric field between the plasma and the electrode. The plasma processing system additionally includes a chuck disposed above the electrode. The chuck is configured for holding the substrate during processing. The electrical field has a first impedance between the electrode and the plasma in the region of the chuck. The plasma processing system further includes an edge ring disposed above the electrode and adjacent to the chuck. The edge ring is configured for shielding at least the electrode from the plasma. The plasma processing system also includes an impedance matching layer disposed between the edge ring and the electrode. The impedance matching layer is configured for controlling a second impedance between the electrode and the plasma in the region of the edge ring. The second impedance is arranged to be substantially equal to the first impedance such that the electrical field between the plasma and the electrode at the surface of the substrate is substantially uniform when the substrate is disposed on the chuck for processing.
The invention relates, in another embodiment, to a substrate pedestal for processing a substrate with a plasma. The substrate pedestal includes an electrode for generating an electric field above the substrate. The electrode has an outer periphery that is larger than an outer periphery of the substrate. The substrate pedestal further includes a chuck for holding the substrate during processing. The chuck is disposed on a top surface of the electrode. The substrate pedestal additionally includes an edge ring for shielding the electrode and the chuck from the plasma. The edge ring is disposed above the electrode. The edge ring has a first portion and a second portion. The first portion is configured to surround the edge of the substrate when the substrate is held by the chuck for processing. The second portion is configured to surround the edge of the chuck, wherein the second portion is disposed between the electrode and the substrate during processing. The substrate pedestal also includes an impedance matching layer disposed between the edge ring and the electrode. The impedance matching layer is configured to control an impedance of the electric field through the chuck, the edge ring and the substrate. The impedance is arranged to affect the electric field to improve processing uniformity across the surface of the substrate.
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Ellingboe Albert R.
Hao Fangli
Lenz Eric H.
Alejandro Luz
Beyer Weaver & Thomas LLP
Lam Research Corporation
Mills Gregory
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