Coating apparatus – Gas or vapor deposition – With treating means
Reexamination Certificate
1999-01-12
2001-11-27
Mills, Gregory (Department: 1763)
Coating apparatus
Gas or vapor deposition
With treating means
C118S719000, C118S730000, C118S725000, C118S625000, C118S638000, C118S641000
Reexamination Certificate
active
06321680
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to methods and apparatus for plasma enhanced chemical vapor deposition (PECVD) on wafers and plasma enhanced etching of wafers, and more particularly to a method and apparatus for transmitting RF energy to create a localized glow discharge over surfaces of wafers stacked vertically on a rotating wafer boat, and apparatus for robotically inserting and removing the wafers.
2. Brief Description of the Prior Art
There are a large number of plasma enhanced processes that are performed inside of enclosed chambers wherein the pressure, temperature, composition of gases and application of radio frequency (RF) power are controlled to (a) produce the desired thin film deposition of various materials onto substrates such as semiconductor wafers, flat panel displays and others, and (b) to remove various materials from such substrates via etching. For convenience, the term “wafer” as used in the following description of the prior art and in the disclosure of the present invention will be used with the understanding that the invention also applies to the manufacture of flat panel displays and other types of substrates or devices wherein plasma enhanced processes are employed. For example, silicon nitride is typically deposited via plasma enhanced chemical vapor deposition (PECVD) on top of metal layers on a semiconductor wafer. A main feature of PECVD processes is that they can be carried out at low substrate temperatures as described by S. Wolf and R. N. Tauber, “Silicon Processing for the VLSI Era”, Volume 1-Process Technology, Lattice Press, 1986, pp. 171-174.
FIG. 1
shows a chamber
10
having a rotating susceptor
12
capable of holding a plurality of substrates. RF energy is applied to an upper electrode
14
to create an electric field causing a plasma (glow discharge) creating free electrons within the plasma region
16
. The electrons gain sufficient energy from the electric field so that when they collide with gas molecules, gas-phase dissociation and ionization of the reactant gases (e.g. silane and nitrogen) occurs. The energetic species are then adsorbed on the film surface.
FIG. 2
shows another prior art device including a single wafer PECVD chamber
18
wherein a wafer
20
is held stationary. There are a variety of single wafer PECVD chamber designs available in the marketplace. There are also a variety of commercially available multiple wafer chambers as described above wherein the wafers are all supported by a susceptor in a single horizontal plane.
The single wafer and horizontal multiple wafer PECVD chamber designs discussed above are problematic for numerous reasons. First, such single wafer designs suffer from relatively low throughput as only one wafer at a time can be processed. Further, the multiple wafer horizontal designs pose extreme difficulties in connection with the incorporation of automatic robotic wafer loading and unloading. Also, horizontal multiple wafer designs can process only a limited number of wafers before the chamber becomes so large in area as to become very difficult to maintain the necessary plasma uniformity and necessary gas flow control.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide a PECVD chamber that can process multiple wafers in a uniform enhanced plasma environment.
It is a further object of the present invention to provide a PECVD chamber having facility for automatic robotic loading and unloading of wafers.
It is a still further object of the present invention to provide a PECVD chamber system including apparatus for transmitting RF energy to a rotating wafer boat having wafers held horizontally in a vertically spaced array, causing a glow discharge, and thereby enhanced plasma over a surface of each wafer.
Briefly, a preferred embodiment of the present invention includes a plasma enhanced chemical vapor deposition (PECVD) system having an upper chamber for performing a plasma enhanced process. and a lower chamber having an access port for loading and unloading wafers to and from a wafer boat. The system includes apparatus for moving the wafer boat from the upper chamber to the lower chamber. The wafer boat includes susceptors for suspending wafers horizontally, spaced apart in a vertical stack. An RF plate is positioned in the boat above each wafer for generating an enhanced plasma. A novel RF connection is provided, allowing the RF energy to be transmitted to the RF plates while the wafer boats are rotated. In addition, apparatus for automatic wafer loading and unloading is provided, including apparatus for lifting each wafer from its supporting susceptor, and a robotic arm for unloading and loading the wafers.
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Brors Daniel L.
Cook Robert C.
Jaffer David H.
Mills Gregory
Pillsbury & Winthrop LLP
Torrex Equipment Corporation
Zervigon Rudy
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