JPH0456785A - Dry etching method - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a dry etching method applied to processing fine patterns of semiconductor devices such as large-scale integrated circuits.

[Conventional technology]

FIG. 2 is a cross-sectional view of a portion of an aluminum wiring pattern of a semiconductor device formed by a conventional dry etching method.

First, an aluminum (A) film is formed on a substrate 1 such as a semiconductor, a photoresist is applied thereon, and a photoresist pattern 2 having a pattern necessary for device configuration is formed using photolithography technology. .

Then, using this photoresist pattern 2 as an etching mask, reactive ion etching (RIE) is performed to remove the All film in the area not covered by the photoresist pattern 2, and a predetermined An) wiring pattern 3 is removed.
is formed.

By the way, when dry etching All by conventional RIE, the etching gas used is boron tribromide (B B
A mixed gas of r s ) and chlorine gas (Cρ2) is used, and at this time, Br supplied from the plasma caused by the discharge of this mixed gas is incorporated into the surface of the photoresist pattern 2, and the surface of the photoresist pattern 2 is As shown in FIG. 3, a C-Br polymer layer 4 is formed.

This C-Br polymer layer 4 has excellent plasma resistance and has the function of protecting the photoresist pattern 2 from plasma, so it has a high etching rate ratio (selectivity) between the etching pattern 2 and the photoresist, and also has a dimensional shift amount. It is possible to perform highly accurate etching with a small amount of etch.

[Problem to be solved by the invention]

In the conventional etching process, as mentioned above, it is possible to achieve a high selectivity, but on the other hand, the photoresist decomposition product AI
Since the so-called sidewall protective film is not sufficiently formed by adhering to the sidewall of the wiring pattern 3, as shown in FIG.
l The side wall of the wiring pattern 3 easily reacts with chlorine molecules, bromine molecules, chlorine radicals (CD'') and bromine radicals (Br'), causing side etching of the A9 wiring pattern 2 and reducing the dimensional accuracy of the Al. However, there was a problem in that the characteristics of the device deteriorated.

This invention was made to solve the above-mentioned problems, and aims to enable highly accurate dry etching of AI or A1 alloy without side etching while maintaining a high selectivity to resist. purpose.

[Means to solve the problem]

A dry etching method according to the present invention uses boron tribromide gas and chlorine gas to dry-etch aluminum or aluminum alloy above a substrate using a predetermined resist pattern as an etching mask, in which hydrogen gas is added to both of the gases. It is characterized by a mixture of

[Effect]

In this invention, since a mixed gas of tribromide gas, chlorine gas and hydrogen gas is used as the etching gas for dry etching, chlorine molecules, bromine molecules and chlorine radicals, which are the cause of side etching of aluminum or aluminum alloy, are removed. .

Bromine radicals react with hydrogen to form hydrogen chloride molecules and hydrogen bromide molecules, and these hydrogen chloride and hydrogen bromide have low reactivity toward aluminum or aluminum alloys in their neutral radical state, and may cause side etching. On the other hand, the surface of the cyst pattern is coated with C-Br as before.
A polymer layer is formed and a high selectivity is obtained.

〔Example〕

FIG. 1 shows a sectional view of an embodiment of the dry etching method of the present invention.

Now, when dry etching the All film on the substrate l using a predetermined photoresist pattern 2 as an etching mask, hydrogen gas (I2) is added in addition to the conventional BBR a and CI2, and these mixed gases are Used as etching gas.

In this way, when a mixed gas of BBr, C1, and H is used, chlorine* * molecules and bromine molecules, which were the cause of side etching of the A1 wiring pattern 3 when a mixed gas of BBr and C12 was used as the etching gas, are removed. and CfI and Br react with I2 to form hydrogen chloride (HCII) and hydrogen bromide (HBr),
These HCl and HBr are AI in the neutral radical state.
Since the reactivity to etching is low, side etching does not occur even though the side wall protective film made of resist decomposition products is thin.

Figure 2 shows the flow rates of B B r , CI , and I2 at 20 SCCM, 60 SCCM, and 20 SCCM, respectively.
This shows the relationship between the hydrogen concentration and the side etch amount of A9 when the hydrogen concentration is changed in the range of 0 to 50%, and if the hydrogen concentration is 20% or more, the side etch is Since the amount is 0 and no side etching occurs, B B r 3 .

A mixed gas of CfI and I2 with a hydrogen concentration of 20%.
By doing so, side etching of the A9 wiring pattern 3 can be prevented.

On the other hand, a C-Br polymer layer 4 is formed on the surface of the photoresist pattern 2 by the reaction between B B r a and CI2, as in the conventional case, and it is possible to obtain a high selectivity as in the conventional case.

Therefore, by using a mixed gas of B B r , CI, and H2 as an etching gas for dry etching, side etching of AI can be prevented while maintaining a high selectivity to photoresist as in the conventional method, and high precision AI etching can be achieved. Dry etching becomes possible, and a fine Al wiring pattern with high precision can be obtained.

In addition, although the above-mentioned example explained the case where the wiring pattern is formed of AI, the present invention can be implemented in the same way even when the wiring pattern is formed of A1 alloy.

〔Effect of the invention〕

As described above, according to the dry etching method of the present invention, a mixed gas of boron tribromide gas, chlorine gas, and hydrogen gas is used as an etching gas, so that chlorine, which is a cause of side etching of aluminum or aluminum alloy, is removed. radical.

Neutral gases such as bromine radicals can be inactivated by reaction with hydrogen, and side etching of aluminum or aluminum alloy can be prevented. It is possible to obtain a high selectivity through formation, and it is possible to form a highly precise fine pattern of aluminum or aluminum alloy, which is extremely advantageous in the production of large-scale integrated circuits and the like.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of an embodiment of the trial etching method of the present invention, FIG. 2 is a relationship between the hydrogen concentration of the etching gas and the side etching amount of AN in the method of FIG. 1, and FIG. 3 is a diagram of the conventional etching method. FIG. 3 is a cross-sectional view of an AI wiring pattern formed by dry etching. In the figure, 1 is a substrate, 2 is a photoresist pattern,
3 is an All wiring pattern. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] (1) A dry etching method in which aluminum or aluminum alloy above the substrate is dry etched using boron tribromide gas and chlorine gas using a predetermined resist pattern as an etching mask, characterized in that hydrogen gas is mixed with both of the gases. Dry etching method.