Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2000-04-21
2001-12-11
Powell, William A. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C134S001100, C156S345420, C216S069000, C216S067000, C438S727000, C438S730000
Reexamination Certificate
active
06329297
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates generally to deposition equipment, such as chemical vapor deposition (CVD) equipment used in the manufacture of semiconductor products, and more particularly to an apparatus and method for cleaning parts of a deposition system or etching process wafers using a remote plasma generator.
The fabrication of semiconductor products, such as integrated circuits, often involves the formation of layers on a substrate, such as a silicon wafer. Various techniques have been developed for the deposition processes, as the layers often involve different materials. For example, a metal layer might be deposited and patterned to form conductive interconnects, or a dielectric layer might be formed to electrically insulate one conductive layer from another. Some types of layer formation processes that have been used to form layers of dielectric materials and other materials are CVD processes.
Chemical vapor deposition processes include thermal deposition processes, in which precursor gases or vapors react in response to the heated surface of the substrate, as well as plasma-enhanced CVD (“PECVD”) processes, in which electro-magnetic energy is applied to at least one precursor gas or vapor to transform the precursor into a more reactive plasma. Forming a plasma can lower the temperature required to form a film, increase the rate of formation, or both. Therefore, plasma-enhanced process are desirable in many applications.
When a layer is formed on a substrate some material is usually also deposited on the walls of the deposition chamber and other components of the deposition system as residue. The material on the walls of the chamber is generally undesirable because the residue can build up and become a source of particulate contamination, causing wafers to be rejected. Several cleaning procedures have been developed to remove residue from inside the chamber. One type of procedure, known as a “wet-clean” is performed by partially disassembling the deposition chamber and wiping the surfaces down with appropriate cleaning fluids. Other types of cleaning processes utilize a plasma to remove the residue by converting it to a volatile product that can be removed by the chamber exhaust system. These processes are known as “dry” cleans.
There are two general types of plasma dry cleaning processes. One type forms a plasma inside the processing chamber, or “in situ”. The other type forms a plasma in a remote plasma generator and then flows the plasma into the processing chamber. Such a remote plasma cleaning process offers several advantages, such as providing a dry clean capability to a deposition system that does not have an in situ plasma system. Furthermore, a remote plasma system might be more efficient at converting cleaning plasma precursor gases or vapors into a plasma, and forming the plasma outside the chamber protects the interior of the chamber from potentially undesirable by-products of the plasma formation process, such as plasma heating and sputtering effects.
Some remote plasma systems use an inexpensive magnetron device, such as is used in consumer microwave ovens. Magnetrons are typically sold with a rated power output, and the remote plasma system is typically designed with the magnetron output power in mind. However, semiconductor substrates come in a variety of sizes. For example, many semiconductor fabrication facilities use 200 mm wafers, while other fabrication equipment is configured to process 300 mm wafers. It would be desirable to use a standard remote plasma system on a variety of processing equipment. Therefore, it is desirable to develop scaleable cleaning processes that can be adapted for various system configurations.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for cleaning a deposition apparatus and for etching substrates in an efficient manner. In one embodiment, a microwave remote plasma generator generates plasma from a precursor gas. The plasma is diluted by mixing the plasma from the remote plasma generator with a diluent gas before flowing the mixture into the deposition chamber through a gas inlet, such as a gas distribution faceplate or similar structure. Diluting the plasma after formation of the plasma allows a greater total gas flow into the chamber through the faceplate without diluting the precursor gas in the plasma generator, thus maintaining the efficiency of the remote plasma generator for creating plasma. The greater flow also provides a higher velocity within the chamber, transporting plasma species, which decay over time, further in the same time period. This results in a higher concentration of plasma species further from the gas inlet, and improved cleaning or etching in the regions further from the gas inlet. Furthermore, by diluting the plasma, it is believed that the recombination of plasma species into less reactive or nonreactive species is inhibited. The result is a faster cleaning or etching process than is obtained using a non-diluted plasma for a given chamber.
In another embodiment, an etching plasma from a remote plasma generator is diluted to form an etching mixture. The etching mixture is used to etch a film on a process wafer in a processing chamber. Control of the etching rate and the etching profile across the diameter of the process wafer is achieved by selecting the amount of diluent in the etching mixture.
These and other embodiments of the present invention, as well as its advantages and features, are described in more detail in conjunction with the text below and attached figures.
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Balish Kenneth E.
Beals Mark
Nowak Thomas
Tanaka Tsutomu
Applied Materials Inc.
Powell William A.
Townsend & Townsend & Crew
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