Semiconductor device manufacturing: process – Coating with electrically or thermally conductive material – To form ohmic contact to semiconductive material
Reexamination Certificate
2002-10-25
2004-05-04
Picardat, Kevin M. (Department: 2822)
Semiconductor device manufacturing: process
Coating with electrically or thermally conductive material
To form ohmic contact to semiconductive material
C438S627000, C438S643000, C438S687000
Reexamination Certificate
active
06730594
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is directed to a technique for use in a method of manufacture of a semiconductor device and to a semiconductor device produced by the method; and, more in particular, it relates to a technique that is effective when applied to a method of manufacturing a semiconductor device having buried wirings comprising copper as a main conductor layer and a semiconductor device.
A buried wiring structure is formed by burying a wiring material into wiring openings, such as wiring grooves or holes, formed in an insulative film, by use of the wiring forming technique referred to as a Damascene technique (Single-Damascene technique and Dual-Damascene technique).
However, when the main wiring material is made of copper, since copper tends to diffuse more into the insulative film compared with other metals, such as aluminum, the surface (bottom and the lateral side) of buried wirings typically is covered with a thin barrier metal film so that the buried wirings comprising copper are not in direct contact with the insulative film, thereby suppressing or preventing copper in the buried wirings from diffusing into the insulative film. Further, an insulative film for a wiring cap comprising, for example, a silicon nitride film is formed on the upper surface of an insulative film in which wiring openings are formed to cover the upper surface of the buried wirings, so that copper in the buried wirings is suppressed or prevented from diffusing from the upper surface of the buried wirings into the insulative film.
The Damascene wiring technique is described, for example, in Japanese Patent Laid-Open No. Hei 11 (1999)-233630, which discloses a technique in which an SiON film is used as the insulative film for a wiring cap. Further, Japanese Patent Laid-Open No. 2000-133710, for example, describes a technique in which a silicon nitride film of high Si content is used as the insulative film for a wiring cap. Further, Japanese Patent Laid-Open No. 2000-252286, for example, discloses a technique in which hydrogen atom-containing silicon is used as the insulative film for a wiring cap (dielectric constant &egr;=4). Further, Japanese Patent Laid-Open No. 2000-332102 discloses a technique in which a BCB film (&egr;=2.7) is used as the insulative film for a wiring cap. Further, Japanese Patent Laid-Open No. Hei 10(1998)-150105, for example, discloses a technique in which an organic low dielectric film (&egr;=2.3-2.6) is used as an insulative film for a wiring cap. Further, Japanese Patent Laid-Open No. Hei 11(1999)-243147, for example, discloses a technique in which an SION film is used as an inter-layer insulative film in a Damascene wiring structure.
SUMMERY OF THE INVENTION
In recent years, for attaining a high performance semiconductor device that is capable of high speed operation, a structure using copper as the main wiring material has been adopted, as described above, with an insulative film of low dielectric constant being used as the material for the insulative film in which the wiring openings are formed. According to a study by the present inventors, it is essential to use an insulative film of low dielectric constant also as a material for the insulative film for a wiring cap, as described above, in order to obtain a higher speed of operation.
In view of the above, the present inventors have examined the introduction of a silicon oxynitride film (SiON), with a dielectric constant that is lower than that of the silicon nitride film, as a material for the insulative film for a wiring cap. Also, it has been found for the first time by the present inventors that the technique of using a SiON film as the insulative film for a wiring cap involves the following considerations.
That is, since an oxygen-containing gas, such as N
2
O, is used for deposition of an SiON film, oxygen activated in the initial stage of film deposition directly hits on a barrier metal film that is exposed to the film deposition surface and oxidizes the exposed portion of the barrier metal film, so as to deteriorate the barrier property near the boundary between the insulative film for a wiring cap and the buried wirings, thereby to shorten the TDDB life.
An object of the present invention is to provide a technique that is capable of improving the dielectric breakdown strength between wirings using copper as a main conductor layer.
The foregoing and other objects, as well as novel features of this invention, will become apparent by a reading the descriptions in the present specification, with reference to the appended drawings.
Among the aspects of the present invention disclosed in this application, an outline of typical features of the invention will be briefly explained below.
That is, according to this invention, an insulative film for a wiring cap is formed such that a conductive barrier film of wirings comprising copper as the main wiring material is not oxidized.
This invention provides, as a first feature, a method of manufacture of a semiconductor device, comprising the following steps of:
(a) forming a wiring opening to a first insulative film deposited on a wafer;
(b) forming wirings in the wiring opening, the wirings including a first conductor film having a barrier property to block the diffusion of copper and a second conductor film comprising copper as a main ingredient; and
(c) depositing a second insulative film for protecting the first conductor film against oxidation on the first insulative film and the wirings, and then depositing a third insulative film on the second insulative film by a chemical vapor deposition method using an oxygen-containing gas.
Preferably, the second insulative film comprises a silicon nitride film. Also, the second insulative film may comprise a silicon carbide film or a silicon carbonitride film. Preferably, the third insulative film comprises a silicon oxynitride film formed by a chemical vapor deposition method using a gas mixture containing a trimethoxysilane gas and a nitrogen oxide gas. Preferably, the thickness of the second insulative film is less than that of the third insulative film.
This invention provides, as a second feature, a method of manufacture of a semiconductor device, comprising the following steps of:
(a) forming a wiring opening to a first insulative film deposited on a wafer;
(b) forming wirings in the wiring opening, the wirings including a first conductor film having a barrier property to block the diffusion of copper and a second conductor film comprising copper as a main ingredient; and
(c) depositing a second insulative film on the first insulative film and the wirings under the condition that the first conductor film is not oxidized, and then depositing a third insulative film on the second insulative film by a chemical vapor deposition method using an oxygen-containing gas.
Preferably, the second insulative film comprises a silicon oxynitride film formed by a chemical vapor deposition method using a gas mixture of a trimethoxysilane gas and a nitrogen gas or an ammonia gas. Preferably, the third insulative film comprises a silicon oxynitride film formed by a chemical vapor deposition method using a gas mixture containing a trimethoxysilane gas and a nitrogen oxide gas.
This invention provides, as a third feature, a method of manufacture of a semiconductor device comprising the following steps of:
(a) forming a wiring opening to a first insulative film deposited on a wafer;
(b) forming wirings in the wiring opening, the wirings including a first conductor film having a barrier property to block the diffusion of copper and a second conductor film comprising copper as a main ingredient; and
(c) depositing a second insulative film by a chemical vapor deposition method using a gas mixture containing an oxygen-containing gas and a dilution gas on the first insulative film and the wirings, and then depositing a third insulative film on the second insulative film by a chemical vapor deposition method using an oxygen-containing gas.
In the preferred embodiment, the second insulative film compr
Hamada Naohide
Noguchi Junji
Antonelli Terry Stout & Kraus LLP
Picardat Kevin M.
Renesas Technology Corp.
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