JPS59123771A - Method for dry-etching copper-aluminum alloy film - Google Patents

Abstract

PURPOSE:To allow an Al alloy film contg. Cu to show a useful anticorrosive effect by generating reactive ions under reduced pressure and impressed high frequency power using a gaseous mixture consisting of a chlorine compound, Cl2 and H2 to dry-etch the alloy film. CONSTITUTION:A Cu-Al alloy film is etched under 20-150mTorr pressure and 0.1-0.4W/cm<2> high frequency power using a gaseous mixture prepd. by adding Cl2 and H2 to a gaseous chlorine compound. The added H2 and Cl2 decompose and remove effectively chlorine compounds as reaction products, especially copper chloride, so etching after the dry etching, a so-called after-etching phenomenon is remarkably controlled. The dry etching method of this invention is useful as a technique for finely working a wiring layer in a highly integrated semiconductor device or the like.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a technique for etching a copper-containing aluminum film used for wiring in highly integrated semiconductor devices.

Conventional Structures and Their Problems In highly integrated semiconductor devices, dry etching technology for aluminum films is used to form fine interconnections. When dry etching an aluminum film, chlorine or chlorine compound gas is usually used. However, according to the conventional tri-etch method, residues of reaction products that appear to be chlorine-based compounds adhere to the surface of the semiconductor substrate or the photoresist pattern, and when this is taken out into the atmosphere, it absorbs moisture from the atmosphere. A so-called post-etching corrosion phenomenon in which aluminum is corroded may occur due to the reaction with aluminum. In particular, when copper is contained in the aluminum film (d), corrosion is severe and this is often the cause of disconnection in minute wiring patterns.For this reason, immediately wash with water after the dry etching process. In particular, when copper-containing aluminum films are used, corrosion progresses rapidly, and anticorrosion treatment after the dry etching process is essential. Even its effectiveness could not be recognized.

The object of the invention is to provide an anti-corrosion treatment method which is particularly useful as a post-treatment technique for dry etching copper-containing aluminum.

Structure of the Invention The present invention uses Hanadai gas (which has added chlorine 2 and hydrogen) to the chlorine compound residue, and the pressure is 20 to 150 mTorr.
r+: fi frequency power Q. 1 to 0.4 W/crrr (copper-aluminum alloy) which etches within the range of 1 to 0.4 W/crrr. It was clear that the decomposition and removal of copper chloride was a two-dimensional process.
Using a mixed gas with a flow rate ratio of CCM units), the reaction chamber pressure was 26 m Torr, and the high frequency power density was 0.2 W.
/ca under conditions of
The aluminum alloy film of u (0.5%) was subjected to dry etching treatment, and then the photoresist was removed. As a result, no corrosion phenomenon was observed in the aluminum alloy film of the wiring.

1, using a mixed gas with a flow rate ratio of BCl2:C10:H2=5:5:6 (all in seaM units),
Pressure 100mTorr, high frequency power density 0, 2W10
Under the conditions of 1, At-Si (1.0%
) When a -Cu (0.5%) aluminum alloy film was dry-etched into a desired wiring pattern using a resist mask, no corrosion paste occurred after the process.

2.According to experience, the pressure inside the reaction chamber is 20~'+5
0m Torr, high frequency power density 01~04W/c4
A remarkable anticorrosion effect was observed within the range of .

In dry etching technology for aluminum films, if hydrogen is added to chlorine compound residue, such as CCt4 gas, the etching rate will decrease, whereas if chlorine is added, the etching rate will be increased. As is known, since hydrogen and chlorine are added simultaneously in the present invention, the etching rate can be optimized by adjusting the H2/Ct2 ratio.

When a copper-containing aluminum film is dry-etched using a chlorine compound gas, copper chloride is produced as a reaction product, which further promotes the 1t5 eclipse of the aluminum alloy film. It is presumed that the corrosion phenomenon is suppressed because chlorine is reduced to copper and still removed from the system as HCt. Considering such a reaction system, if the pressure inside the reaction chamber is less than 20m Torr, the reaction progresses slowly.
It is unsuitable for patterning, and furthermore, the pressure is 1
When the pressure exceeds 50 m Torr, the speed of the fangs increases due to the progress of the reaction.
At the same time, etching of the photoresist mask was also observed, and fine patterning was avoided. As for the high frequency power density, it is less than 0.1 WlcA. For yellow color 1, the etching curve was weak, and on the other hand, when it exceeded 0.4 W/cI7f, the sputtering strength was strong, and both were unfavorable in terms of thermal and dynamic properties.

More detailed than the effects of the invention [7] According to the present invention, dry etching of an aluminum alloy film containing copper can be reliably performed, and a reactive gas containing chlorine and hydrogen added to a chlorine compound gas can be used. By using this, corrosion after dry etching treatment, so-called post-corrosion phenomenon, is significantly suppressed. Therefore, the present invention is useful as a technology for reducing the power of fine wiring layers in ultra-highly integrated semiconductor devices and the like.

Claims (3)

[Claims] (1) Tri-etching method for a copper-aluminum alloy film using a chlorine compound, a mixed gas of chlorine and hydrogen, and performing etching treatment with reactive ions under reduced pressure and application of high-frequency power. (2) The tri-etch crab of an aluminum alloy film according to claim 1, wherein the reaction chamber pressure is selected to be in the range of 20 to 150 mTorr. (3) The copper according to claim 1, wherein the density of high-frequency power application is selected to be in the range of 0.1 to 0.4 W/M.
How to dry etch an aluminum alloy film.