JPS62232926A - Dry etching - Google Patents

Abstract

PURPOSE:To increase etching speed to reduce a side etching, by performing a dry etching of an a film or Al alloy film by the use of a reactive gas which contains BCl3, SiCl4, Cacute angle2, O2, and fluorine. CONSTITUTION:A reactive gas is introduced between electrodes 2 aud 3 from a gas-introducing part 1. High frequency electric power generated by a high frequency power supply 5 is impressed between the electrodes 2 and 3. An Al film or Al alloy film on a processed matter 4, which is arranged on the electrode 3, is etched by the plasmic reactive gas. The reactive gas containing BC$;3, SiCl4, Cl2, O2, and fluorine is used then.Hence, an etching speed is increased to reduce a side etching.

Description

[Detailed Description of the Invention] [Summary] The present invention introduces a reactive gas to generate plasma,
When dry etching an aluminum film or an aluminum alloy film, BCIs and S are used as reactive gases.
i Cj! By using a mixed gas containing s, C1z, Ox%, and fluorine, the etching rate is increased, the selectivity is improved, and side etching is reduced.

[Industrial application field]

The present invention uses BCβ, 5iC11a as a reactive gas.
, C11z, Ox, and fluorine as a reactive gas.

[Prior art and problems to be solved by the invention] In the process of manufacturing inter-electrode wiring of semiconductor devices, an aluminum film is formed on a semiconductor substrate using a vapor deposition method or a sputtering method, and then a photoresist is applied as a mask. Dry etching methods, in which a predetermined pattern is formed by etching, have become mainstream as patterns become finer in recent years. When etching an aluminum film or the like using this dry etching method, the reactive gas introduced is conventionally t3c7! ,,SiC'24
- Simple gases such as PClv and ccg, or mixed gases in which 012 is mixed with these simple gases, have been used. When etching an aluminum film etc. using either of these single gases or 7-containing gases,
It has problems such as etching speed, etching speed distribution, selectivity to resist/mask, selectivity to 5iOz substrate, processed shape, and corrosion after etching.
There is a problem in that it is difficult to use etching to generate a wiring pattern of about μTn. In particular, Bc
e, and CI! A reactive gas containing a mixture of , and etching can be used to perform etching with a small amount of residual layer, and there is no corrosion after etching, and there is less leakage in the etching chamber. Because it has little off-odor, it was used as a reactive gas for mass production. In particular, by mixing O7 with this to increase the etching rate and further mixing with a fluorine gas such as CF, more effective dry etching with less corrosion after etching was possible.

However, in this gas system, when trying to obtain high selectivity for the photoresist l, which is a mask, side etching tends to proceed, and on the other hand, when trying to suppress side etching, the selectivity decreases. However, there is a problem in that etching a fine pattern of about 1 μm is extremely difficult.

For example, in this gas system, if the etching conditions are set such that the etching rate of aluminum is 1800 people/min and the selectivity to photoresist is 3,
Side etching will occur.

On the other hand, if the etching conditions are set so that side etching does not occur, the selectivity to the photoresist can only be as low as about 2.5, resulting in a problem in that fine patterns cannot be etched.

[Means for solving problems]

In order to solve the above problems, the present invention provides BCl22
, S i C11a , C11z , OX , and a reactive gas containing fluorine to dry-etch the aluminum film or aluminum alloy film, thereby increasing the etching rate (and improving the selectivity and side etching). I'm trying to reduce it.

Means for solving the problems will be explained using the configuration of one embodiment of the present invention shown in FIG.

In FIG. 1, the gas introduction section 1 includes BCjlff, S
This is for introducing a reactive gas containing i C(la , C1z , Ox , and fluorine between electrode 2 and electrode 3 ).

The electrodes 2 and 3 are used to apply high frequency power to turn the reactive gas introduced between the electrodes 2 and 3 into plasma.

The workpiece 4 is placed on the electrode 3 as shown, for example, and is a silicon wafer on which an aluminum film or an aluminum alloy film is deposited.

The high frequency power aS is a power source for supplying high frequency power between the electrodes 2 and 3.

[Effect]

Adopting the configuration explained using FIG. 1, BCf, , S i (1!a, (1
! 2.0. , and a gas containing fluorine such as CF or CHFt is added to the gas introduction section 1.
When the high-frequency power generated by the high-frequency power source 5 is introduced between the electrodes 2 and 3 and applied between the electrodes 2 and 3, the reactive gas is turned into plasma. This plasma-formed reactive gas etches the aluminum film or aluminum alloy film on the workpiece 4 placed on the electrode 3.

At this time, since a reactive gas containing BCI3.5iC14, C12,02, and fluorine is introduced, it is possible to perform processing with a high etching rate, good selectivity, and little side etching.

〔Example〕 Next, use Figures 1 to 3 to determine the BCI.

, S i C1a , C(12, Oz , and CF
A reactive gas consisting of a mixed gas to which a fluorine-containing gas such as a or CHFff is added is applied to electrodes 2 and 3.
The selectivity and side etching amount characteristics when the workpiece 4 is etched by introducing plasma into plasma will be explained in detail.

B CILx / Cj! is widely used for mass production as a reactive gas for etching aluminum films or aluminum alloy films. When using the Z gas system, as mentioned above, in order to prevent side etching, the selectivity for the photoresist mask has to be lowered to about 2.5, and a fine pattern of about 1 μm or less can be etched and generated. It is extremely difficult to do so. Therefore, in the present invention, in addition to the addition of 3iCj24, which forms a sidewall (side etch) protective film and enables anisotropic etching, as a reactive gas for etching aluminum films, etc., BCf2, which improves the etching rate distribution, is added. , C12 and 02 to improve the etching speed, and CF to prevent corrosion and contamination of the chamber after etching, or a gas mixture containing fluorine gas such as CHF z is used.4 Using a reactive ion etching apparatus having the configuration shown in Fig. 1, an aluminum-silicon alloy film was etched with BCli, Cl1t, 02 under the condition of RF (radio frequency) power density of 0°2 W/cm2. The dotted line shows the selectivity when a mixed gas consisting of BCl, , CF4 and CF4 is used as the reactive gas.
,,S 1c11.0. and CF (e.g. total flow 1100-200 sccm S mixing ratio 30
:25:30:5:10) is used as the reactive gas, is shown using a solid line. In the figure, the horizontal axis shows the pressure (Pa) of the reactive gas, and the vertical axis shows the selectivity with respect to the photoresist.

As can be seen with reference to FIG. 2, BClx, C1t, S1C1a, according to the present invention shown using solid lines,
The photoresist selectivity characteristic curve for etching using a mixed gas of Ot and CF4 as the reactive gas always has a greater selectivity value for the photoresist than the one shown using the dotted line.

FIG. 3 shows the side etching amount and overetching amount characteristics when etching is performed under the conditions of an RF III electrode of 0.2 W/cm'' and a reactive gas pressure of 8 Pa.

As can be seen with reference to FIG.
When using the reactive gas according to the present invention mixed with 1 g of iCl, side etching hardly occurs even during long-term over-etching. In particular, in order to completely etch the stepped portions of highly integrated semiconductor devices, long-term over-etching is required, but when a 5iCj14 mixed gas system is used as the reactive gas, long-term over-etching is required. This is an extremely effective etching method, with almost no side etching observed. In addition, for example, Si/A containing aluminum film
j! / S i , A l / S i , A
I2/TiW, Aj! /TiN,Aj! /MoSi2,
A7! This is also an effective etching method when etching a multilayer film such as /W S it.

When etching an aluminum/silicon wiring pattern on a wafer with a diameter of 150 mm using the reactive gas according to the present invention, the etching speed was 2,600 people/day.
min, selectivity to the photoresist mask of 4 could be obtained with almost no side etching. Moreover, when etching was performed using the reactive gas according to the present invention, almost no corrosion occurred after etching. Furthermore, contamination by reaction products in the etching chamber
Compared to the conventional method (using a mixed gas consisting of DBCI13, C12, CF4, and O2 as the reaction gas), the level of contamination is reduced to the same level, and there is less irritating odor remaining in the etching chamber, making it easier to clean the inside of the etching chamber. I was able to do it.

Although CF a was used as the gas containing fluorine to obtain the characteristic curves shown in FIGS. 2 and 3, it is not limited to this, and CHFs, Cx Fa, NF, SF,
Any material containing fluorine, such as, may be used.

〔Effect of the invention〕

As explained above, according to the present invention, BCl3.5i
Since the aluminum film or aluminum alloy film is dry-etched using a reactive gas containing C14, C12, 02, and fluorine, the aluminum film or aluminum alloy film can be etched at high speed and selectively. It is possible to obtain an excellent processed shape with good properties and less side etching.

[Brief explanation of drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a photoresist selectivity characteristic diagram, and FIG. 3 is a side etching amount characteristic diagram. In the figure, 1 is a gas introduction part, 2.3 is an electrode, 4 is a workpiece,
5 represents a high frequency power source.

Claims (1)

[Claims] In a dry etching method in which a reactive gas is introduced to generate plasma to dry-etch an aluminum film or aluminum alloy film, a mixed gas consisting of a gas containing BCl_3, SiCl_4, Cl_2, O_2, and fluorine is introduced as a reactive gas. A dry etching method characterized by: