Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2002-06-18
2003-12-16
Tsai, Jey (Department: 2812)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S003000, C438S240000
Reexamination Certificate
active
06664184
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a technique for manufacturing a semiconductor device, and more particularly relates to the fine working of at least one type of conductor film selected from among a ruthenium film, a ruthenium oxide film, an osmium film, and an osmium oxide film.
2. Description of the Related Art
In an effort to increase the capacity of DRAM cell capacitors, there have been attempts at forming the capacitor dielectric film of a DRAM cell from a multi-element oxide with a high dielectric constant (such as BaSrTiO
3
). From the standpoint of the ease of working by dry etching, the use of ruthenium, ruthenium oxide, and the like has been studied for electrode materials combined with these multi-element oxides. The technique discussed in Japanese Laid-Open Patent Application H8-78396 is known as a dry etching technique for the fine working of a conductor film formed from one of these electrode materials.
With this technique (hereinafter referred to as the conventional etching method), a ruthenium film or ruthenium oxide film on a silicon substrate is selectively etched using a plasma of a halogen gas (fluorine gas, chlorine gas, iodine gas) or a mixed gas of a hydrogen halide gas and oxygen gas (or ozone gas).
The techniques discussed in Japanese Laid-Open Patent Applications H6-283438 and H9-246214 are known as techniques for forming a film of ruthenium oxide or the like. The former technique involves depositing a ruthenium oxide film with a low resistivity value on the surface of a substrate such as silicon by MOCVD (Metal Organic Chemical Vapor Deposition) using dipivaloyl methanate ruthenium as the raw material. The latter technique involves stably depositing a ruthenium film or a ruthenium oxide film on a substrate surface by MOCVD using liquid or vaporized 2,2,6,6-trimethyl-3,5-heptanedione ruthenium as the raw material.
Known publication in which other related technology is discussed include Japanese Laid-Open Patent Application 2000-200782.
SUMMARY OF THE INVENTION
The conventional etching methods discussed above, however, do not deal with avoiding the damage to the substrate caused by the plasma. Moreover, the resist mask is also etched by the oxygen-based gas contained in the etching gas, which makes it very difficult to form the proper circuit pattern. Furthermore, a plasma etching apparatus is quite costly, and using one of the above conventional etching methods leads to higher cost in the manufacture of a semiconductor device.
In view of this, it is an object of the present invention to provide a method for manufacturing a semiconductor device, with which a semiconductor device having at least one type of conductor film selected from among a ruthenium film, a ruthenium oxide film, an osmium film, and an osmium oxide film can be manufactured inexpensively and at a high level of quality.
To achieve the stated object, the present invention is constituted such that when at least one type of conductor film selected from among a ruthenium film, a ruthenium oxide film, an osmium film, and an osmium oxide film is etched, impurities containing carbon are removed from the conductor film prior to this etching.
This allows a semiconductor device with excellent quality to be manufactured at a low cost.
REFERENCES:
patent: 6541813 (2003-04-01), Niwa et al.
patent: 06-283438 (1994-10-01), None
patent: 08-078396 (1996-03-01), None
patent: 09-246214 (1997-09-01), None
patent: 10-163178 (1998-06-01), None
patent: 10-209132 (1998-08-01), None
patent: 2000-183034 (2000-06-01), None
patent: 2000-183303 (2000-06-01), None
patent: 2000-200782 (2000-07-01), None
patent: 2000-223671 (2000-08-01), None
patent: 2001-284317 (2001-10-01), None
patent: 2001-284330 (2001-10-01), None
Nakahara Miwako
Tsunekawa Sukeyoshi
Watanabe Kazuto
Hitachi , Ltd.
Townsend and Townsend / and Crew LLP
Tsai Jey
LandOfFree
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