JPH04284628A - Dry etching method - Google Patents

Abstract

PURPOSE:To provide a method which does not cause a residue at an etching treatment process. CONSTITUTION:This is a dry etching method by which Al or an Al alloy layer 22 on a substrate 21 is etched in the atmosphere of a rare gas which is supplied from a gas bomb 5. Thereby, it is possible to prevent a residue from being caused on the substrate.

Description

[Detailed description of the invention]

[Purpose of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to improvements in dry etching methods.

0002

2. Description of the Related Art In the manufacture of semiconductor devices, etc., Al (aluminum) or Al alloy (for example, Al-Si-Cu alloy, double-layered Al
-Si-Cu/TiN, Al-Si-Cu/TiW, etc.)
There is a process of performing wiring processing using materials. Conventional wiring processing is performed by dry etching a layer such as Al formed on a substrate.
As shown in FIG. 2, a substrate sample 2 is placed on a lower electrode 11 in a reaction chamber 1, and the reaction is carried out in a gas atmosphere containing, for example, a deposition gas of Cl2 and HBrBBr3 supplied through a reaction gas inlet 12. The reaction gas inlet 12 is connected to the gas cylinder 3 via a mass flow controller 31 and a valve 32.
It is connected to the. 13 is the upper electrode, and the lower electrode 1
A high frequency power source 4 is connected between the reaction chamber 1 and the reaction chamber 1, and plasma is formed in the reaction chamber 1. In addition, 14 is an exhaust port,
It is connected to an exhaust pump (not shown) to keep the pressure inside the reaction chamber 1 constant.

As shown in FIG. 4A, the state of the substrate sample 2 before the start of dry etching is such that a wiring pattern is formed using a resist 23 on an Al layer 22 with a substrate 21 as a base. Therefore, in the plasma-generated chlorine-based gas atmosphere in the reaction chamber 1, Al based on the resist 23 is
As the etching of the layer 22 progresses, as shown in FIG. 4(b), a protective film 22a is formed in the lateral direction while a normally tapered cut surface is formed due to anisotropy, and a wiring portion made of Al is formed. .

However, in the conventional dry etching method described above, the Al layer 22 is removed by reacting with chlorine-based or bromine-based gas and chlorine-based or bromine-based ions or radicals in the plasma to generate volatile products. However, for example, Si or Cu
etc. are deposited as residues on the upper surface of Al or on the underlying surface during the etching process. This is called a residue 24 and appears on the substrate 21 as an etching residue. Al alone as a wiring material is often used containing about 1% Si and 0.5% Cu, so if the Al layer 22 contains copper, for example, it becomes a copper residue (24). Precipitate. In order to prevent the generation of the copper residue (24), there is a method of further advancing the etching process, and a method described in Japanese Patent Application Laid-Open No. 64-5354
As described in Japanese Patent Application No. 81227, there is a method of controlling the temperature of the substrate sample 2 during reaction or stage temperature so as to be kept within a specific temperature range, and as described in Japanese Patent Application Laid-open No. 81227/1983. As mentioned above, there is a method of changing the type of gas to be supplied and alternately switching and supplying it.

However, if the etching process is allowed to proceed any further, the anisotropic cut surface will collapse, the protective film 22a will be destroyed, and the etching will cut into the lateral direction. It is unsuitable for high-precision wiring processing because it breaks even under the slightest stress. In addition, it is possible to control the temperature of the substrate sample 2 during the reaction or the stage temperature so that it is kept within a specific temperature range, or to change the type of supply gas and alternately switch and supply the gas while the reaction is actually progressing. Detecting the temperature of the gas, controlling the temperature range appropriately, and alternately switching the gas supply, which complicates the configuration and control, and improvements have been desired.

[0006]

Problems to be Solved by the Invention In the conventional dry etching method, a residue of copper or the like is generated on the substrate, and there is no effective and effective means for removing this residue.

SUMMARY OF THE INVENTION An object of the present invention is to provide a dry etching method that eliminates the above-mentioned conventional drawbacks and effectively removes residues formed on a substrate.

[Configuration of the invention]

[0009]

[Means for Solving the Problems] The present invention provides a dry etching method for Al or Al alloy, which is carried out by converting chlorine-based or bromine-based gas into plasma.
It is characterized by etching Al or Al alloy.

0010

[Operation] The dry etching method according to the present invention, as a result of etching Al or Al alloy in a rare gas atmosphere, can eliminate or reduce the amount of residue on the substrate to the extent that it does not pose a practical problem, and eliminates the above-mentioned drawbacks of the conventional method. It can be resolved.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the dry etching method according to the present invention will be described in detail below with reference to FIGS. 1 and 2. Components that are the same as the conventional configurations shown in FIGS. 3 and 4 are given the same reference numerals and detailed explanations will be omitted. That is, as shown in FIG. 1, a substrate sample 2 placed on a lower electrode 11 in a reaction chamber 1 is supplied with chlorine-based gas such as Cl2 or HBr from a first gas cylinder 3 through a reactive gas inlet 12. , bromine-based gas is supplied, and a mass flow controller 51 for controlling the flow rate is supplied so that a rare gas such as Ar, He, or xenon is supplied from the second gas cylinder 5 at a ratio of 30 to 40% by weight in the reaction chamber 1. is adjusted and supplied,
Etching of the substrate sample 2 is performed in these atmospheres. Note that, as in the prior art, the high frequency power source 4 is connected between the upper electrode 13 and the lower electrode 11, and plasma is formed in the reaction chamber 1. As shown in FIG. 2(a), the substrate sample 2 before the start of dry etching has an Al layer 22 formed in advance on a substrate 21 made of Si as a base, and a wiring pattern is formed by a resist 23 on the Al layer 22. It is formed. Next, as the etching of the Al layer based on the resist 23 progresses in the plasma-generated rare gas atmosphere in the reaction chamber 1, as shown in FIG. 2(b), the protective film 2
While forming 2a, an anisotropic cut surface is formed by etching, and no residue (24) is seen on the substrate 21.

[0012] It has not yet been precisely determined whether or not residues that were not removed in the past are generated in the etching process by performing dry etching in an atmosphere containing this rare gas, but it is probably the case that the second The rare gas such as Ar (argon) gas supplied from the gas cylinder 5 is chemically inert, which is the unique property of the rare gas. During the etching process of Al or Al alloy material, the rare gas ions Alternatively, it is presumed that a physical phenomenon is caused by hitting the Cu molecules and preventing them from being deposited as the residue 24.

As a result, according to the present invention, the generation of residue can be eliminated by simply adding a simple configuration of supplying a rare gas, and this will be achieved as more precise wiring processing is required in the future. It is highly effective.

[0014]

[Effects of the Invention] The dry etching method according to the present invention has an excellent practical effect of not generating residue during the etching process, especially on the substrate, and contributes to improving the manufacturing efficiency of substrates such as semiconductor wafers. It's a big deal.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a dry etching apparatus for explaining an embodiment of the dry etching method according to the present invention.

2A is a cross-sectional view of the substrate sample before etching starts, and FIG. 2B is a cross-sectional view of the substrate sample after etching is completed by the apparatus shown in FIG. 1. FIG.

FIG. 3 is a configuration diagram of a dry etching apparatus to which a conventional dry etching method is applied.

4(a) is a cross-sectional view of the substrate sample before etching starts, and FIG. 4(b) is a cross-sectional view of the substrate sample after etching is completed by the apparatus shown in FIG. 3. FIG.

[Explanation of symbols]

1...Reaction chamber 11...Lower electrode 2...Substrate sample 21...Substrate 22...Al layer 23...Resist 24...Residue 3,5...Gas cylinder 31, 51...Mass flow controller

Claims (1)

[Claims] 1. A dry etching method for Al or Al alloy carried out by converting chlorine-based or bromine-based gas into plasma, characterized in that the Al or Al alloy is etched in a rare gas atmosphere.