Semiconductor device manufacturing: process – Chemical etching – Vapor phase etching
Reexamination Certificate
2000-05-12
2002-06-18
Utech, Benjamin L. (Department: 1765)
Semiconductor device manufacturing: process
Chemical etching
Vapor phase etching
C438S722000
Reexamination Certificate
active
06407004
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to thin film devices, typified by semiconductor devices and TFTs (thin film transistors) for use in liquid crystal displays, and to a method for manufacturing the thin film devices. Also, the present invention relates to a magnetic head, as well as a method for manufacturing the magnetic head, to be used for magnetic recorders such as hard disk drives (hereinafter, referred to as HDDs), as a more concrete example of the thin film devices.
In recent years, semiconductor devices have been advancing toward higher integration, while liquid crystal displays have been advancing toward larger size. Further, thin film devices other than these devices, such as SAW devices and micromachines, have been developed into practical use.
A thin film device and a method for manufacturing a thin film device according to the prior art are described below.
In particular, the following description is centered on the pattern forming method using a dry etching process of electrical wiring for a thin film device.
FIGS. 9A and 9B
show a pattern forming process of a conductor layer serving for electrical wiring using the dry etching process in conventional semiconductor devices. The method of forming a conductor layer pattern using the conventional dry etching process is described below.
In
FIGS. 9A and 9B
, in which
FIG. 9A
shows cross-sectional structure of the film before the dry etching and
FIG. 9B
shows that after the dry etching, reference numeral
41
denotes a Si substrate,
42
denotes a gate insulating film formed of a 4 nm thick SiO
2
film,
43
denotes a gate electrode made of tungsten (W) having a film thickness of 150 nm and forming a conductor layer serving as an electrical wiring, and
44
denotes an etching mask for the gate electrode
43
made of SiN. Numeral
43
a
denotes a gate electrode wiring formed by patterning the gate electrode
43
by dry etching.
Now the gate electrode pattern forming process using the dry etching process in conventional semiconductor devices is explained.
First, a Si substrate fabricated up to the etching mask
44
is set in a reaction chamber of a dry etching apparatus. Next, plasma of Cl
2
and O
2
mixed gas is generated, the gate electrode
43
is etched on the basis of the etching mask
44
, and then the etching mask
44
is removed, by which a pattern of the gate electrode
43
is obtained.
However, in this conventional method, during the dry etching process of the gate electrode
43
made of tungsten, the etching selection ratio with SiO
2
, which is the thin gate insulating film
42
as a ground, is as poor as around
10
, and moreover the processing must be done with an enlarged over etching on account of the micro-loading effect that a difference in etching rate occurs between a micro-pattern region and thick pattern region. As a result, as shown in
FIG. 9B
, there occur regions where the ground SiO
2
gate insulating film
42
disappears so that good device characteristics could not be obtained. Also, in the future, as the gate insulating film becomes thinner and thinner with the progress toward higher integration, conventional methods would become insufficient.
Accordingly, an object of the present invention is to provide a thin film device, as well as a method for manufacturing the thin film device, which allows a conductor layer serving as an electrical wiring to be formed at high selection ratio with respect to a ground layer by using a dry etching process.
SUMMARY OF THE INVENTION
In order to achieve the above object, the present invention has the following constitutions.
According to a first aspect of the present invention, there is provided a thin film device in which a conductor layer serving as an electrical wiring in the thin film device is a conductor layer that can be dry-etched by an oxygen-containing gas.
According to a second aspect of the present invention, there is provided a thin film device in which a conductor layer serving as an electrical wiring in the thin film device is formed of two or more conductor layers, and a conductor layer on one side close to a substrate, out of the two or more conductor layers, is a conductor layer that can be dry-etched by an oxygen-containing gas.
According to a third aspect of the present invention, there is provided a thin film device according to the first aspect, wherein the conductor layer that can be dry-etched by the oxygen-containing gas is made of Ru or RuO
2
.
According to a fourth aspect of the present invention, there is provided a thin film device according to the second aspect, wherein an upper layer of the two or more conductor layers contains any one of polysilicon, W, WN, Cu, Al, Ag, and Au.
According to a fifth aspect of the present invention, there is provided a thin film device according to the first aspect, wherein the thin film device is a semiconductor device or a TFT for liquid crystal display.
According to a sixth aspect of the present invention, there is provided a method for manufacturing a thin film device, comprising:
depositing on a substrate a conductor layer which is etchable by an oxygen-containing gas and which serves as an electrical wiring;
forming an etching mask pattern on the conductor layer; and
thereafter, performing dry etching of the conductor layer with plasma of a gas containing at least oxygen to thereby accomplish a patterning of the conductor layer.
According to a seventh aspect of the present invention, there is provided a method for manufacturing a thin film device, comprising:
depositing on a substrate a lower conductor layer which is etchable by an oxygen-containing gas and which serves as an electrical wiring, and depositing one or more upper conductor layers on the lower conductor layer;
forming an etching mask pattern on the conductor layers; and
thereafter, preforming dry etching of the conductor layers with plasma of a gas containing at least oxygen to thereby accomplish a patterning of the conductor layers.
According to an eighth aspect of the present invention, there is provided a method for manufacturing a thin film device according to the seventh aspect, wherein the dry etching of the upper conductor layer is performed with plasma of a halogen-containing gas.
According to a ninth aspect of the present invention, there is provided a method for manufacturing a thin film device according to the sixth aspect, wherein the conductor layer that is etchable by the oxygen-containing gas is made of Ru or RuO
2
.
According to a 10th aspect of the present invention, there is provided a method for manufacturing a thin film device according to the seventh aspect, wherein the upper conductor layer contains any one of polysilicon, W, WN, Cu, Al, Ag, and Au.
According to an 11th aspect of the present invention, there is provided a method for manufacturing a thin film device according to the sixth aspect, wherein the thin film device is a semiconductor device or a TFT for liquid crystal display.
According to a 12
th
aspect of the present invention, there is provided a thin film device as defined in the first aspect, wherein the thin film device is a magnetic head in which the conductor layer serving as the electrical wiring and being dry-etchable by the oxygen-containing gas is a non-magnetic conductor layer electrically connected to a magneto resistive element.
According to a 13
th
aspect of the present invention, there is provided a thin film device as defined in the first aspect, wherein the thin film device is a magnetic head in which the conductor layer serving as the electrical wiring and being dry-etchable by the oxygen-containing gas is a conductor layer electrically connected to a magnetoresistive element and the conductor layer is made of Ru or RuO
2
.
According to a 14
th
aspect of the present invention, there is provided a thin film device according to the 13
th
aspect, wherein the conductor layer is a pair of lead electrodes electrically connected to the magnetoresistive element of the magnetic head.
According to a 15
th
aspect of the present invention, there is provid
Kimura Tadashi
Mitani Satoru
Muragishi Isao
Sakaguchi Masaya
Sekiguchi Hiroyoshi
Chen Kin-Chan
Matsushita Electric - Industrial Co., Ltd.
Wenderoth , Lind & Ponack, L.L.P.
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