JPH0223622A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To form an Al, Si and Cu alloy wiring having resistance against electro-migration with excellent dimensional controllability by shaping a thin Cu layer onto an AlSi alloy, changing the laminated film into a wiring through photo-etching and forming the Al, Si and Cu alloy through heat treatment. CONSTITUTION:An aluminum-silicon alloy 103 is shaped onto an insulating film 102, and copper 104 is formed. A pattern is shaped by a photo-resist 105, and copper 104 and the aluminum-silicon alloy 103 are etched through reactive ion etcthing. The photo-resist 105 is removed, and copper 104 is diffused into the aluminum-silicon alloy 103 through heat treatment for twenty min at 400 deg.C, thus forming an aluminum-silicon-copper alloy 107.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for manufacturing a semiconductor device, and particularly to a method for forming metal wiring.

[Prior Art] In conventional semiconductor devices, an aluminum-silicon alloy is used as metal wiring for boat fishing.

In the manufacturing process, processing by dry etching was also relatively easy. However, as semiconductor integrated circuits have become more highly integrated in recent years, metal wiring patterns have also become finer.

Aluminum atoms move with the current flowing through the metal wiring, leading to disconnection of the metal wiring at that location.

A phenomenon called ``electromigration'' was more likely to occur, which caused problems in terms of reliability. Therefore, in order to prevent this phenomenon, a new aluminum-silicon-copper alloy is being used as a wiring material instead of the conventional aluminum-silicon alloy. When used, aluminum, silicon,
When processing a copper alloy by dry etching, it is impossible to chemically remove the copper in the alloy, so in order to remove the copper, as shown in Figures 2 (a) to (C), Compared to conventional dry etching of aluminum-silicon alloys, it was necessary to suppress the RF power at a higher level and physically remove the sputtering effect using a large comb and impact energy.

[Problems to be Solved by the Invention] However, with the above-mentioned conventional technology, when etching an aluminum-silicon-copper alloy.

Due to the high RF power, the damage caused by the impact of 9 reactive ions is large, the photoresist is altered and deformed, and the dimensional controllability of wiring becomes poor.

In some cases, the insulating film is severely scratched, and furthermore, the device characteristics are deteriorated due to the influence of ion charges.

The present invention is intended to solve these problems, and its purpose is to form metal wiring with high resistance to "electromigration" through dimensional controllability without deteriorating element characteristics. It's about providing a method.

[Means for Solving the Problems] The present invention provides a step of forming a metal mainly composed of aluminum as a first metal wiring layer above a semiconductor substrate, and forming a second metal wiring layer on the first metal wiring layer. A step of forming a metal containing copper as a main component as a metal wiring layer, a step of forming a wiring pattern consisting of the first and second metal wiring layers by photo-etching, and a heat treatment step. It is characterized by

[Example] Process cross-sectional views in Examples of the present invention are shown in Figures 1(a) to 1(a).
It is shown in (e) and will be explained in detail below in the order of steps.

First, as shown in FIG. 1(a), the insulating film 102 is
After forming 10,000 layers of aluminum-silicon alloy 103 on top, 100 layers of copper 104 are subsequently formed. At this time, the silicon content in the aluminum-silicon alloy 103 is 1.0 wt%.

Next, a pattern is formed using photoresist 105.
Etch 1104 and aluminum-silicon alloy 103 by reactive ion etching. The etching conditions at this time are that the gas flow rate is BC13 = 100scc.
m, CC12=30sca, CF4=10sec, 0
2=5sec.

Although the gas pressure is 6 Pa, the RF power is 100 OW when etching the upper layer copper 104 and 800 W after removing the copper 104. R when etching copper
The reason for setting the F power to 100 OW is that, as mentioned above, copper does not react chemically with the above-mentioned reactive gases and must be physically removed using ion bombardment, as shown in Figure 1 (b).
), the RF power is increased to 'iooow', the acceleration voltage of the reactive ions is increased, and the energy of ion bombardment is increased, thereby making it possible to remove copper efficiently. However, if it remains at 100OW, WJ due to reactive ions! 11 is large, causing the same problem as in the prior art described above.

As shown in FIG. 1(C), after the copper 104 is completely removed, the power must be lowered to 800W immediately. In this way, applying high RF power immediately after starting etching can physically damage the chemically stable natural oxide film (alumina) formed on the surface, even when etching a single layer of aluminum-silicon alloy. This has been done with the purpose of removing it, and there are no problems caused by this.

Under these etching conditions, copper 104 was etched for 1 minute.

The aluminum-silicon alloy 103 can be completely etched in about 10 minutes.

After etching the copper 104 and the aluminum-silicon alloy in this manner, the photoresist 106 is removed as shown in FIG. 1(d).

Finally, as shown in FIG. 1(e), the copper 104 is diffused into the aluminum-silicon alloy 103 by heat treatment at 400° C. for 20 minutes, forming an aluminum-silicon-copper alloy 107. The copper content in the aluminum-silicon-copper alloy thus obtained was 3.2 wt%. The copper content in the alloy can be freely changed by changing the combination of the aluminum-silicon alloy and the copper film thickness.

Note that in this embodiment, an aluminum-silicon alloy is used as the first metal wiring layer, but pure aluminum is also acceptable, and the layer contains copper at a low concentration that does not degrade workability by dry etching. There is no problem with aluminum alloy. Further, although copper is used as the second metal wiring, other alloys containing copper as a main component may be used without any problem. Furthermore, for the heat treatment process, 400°
The aluminum-silicon alloy is alloyed with the saw by performing a sintering process for C2O, but there is also no problem with the heat generated during the formation of an insulating film by chemical vapor deposition in the post-process, and laser・There is no problem with heat treatment such as annealing.

This allows us to create aluminum-silicon-copper alloy wiring, which is highly resistant to electromigration, with good dimensional control and without cutting away the underlying insulating film.

Moreover, it has the effect of being able to be formed without deteriorating element characteristics, and as a result, it has become possible to manufacture highly reliable semiconductor devices with high yield.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(e) are process cross-sectional views showing a method of manufacturing a semiconductor device according to the present invention. FIGS. 2(a) to 2(c) are process cross-sectional views showing a conventional method for manufacturing a semiconductor device. [Effects of the Invention] As described above, according to the present invention, a thin copper layer is formed on an aluminum-silicon alloy that can be easily processed by dry etching, and then this laminated film is formed into wiring by photo etching. Heat treated to form aluminum-silicon-copper alloy 101, 201 102, 202 104° 105, 204 Semiconductor substrate insulating film aluminum-silicon alloy copper photoresist 106, 205 108, 203 Ion beam (when RF power is high) Ion beam (When RF power is low) Aluminum, silicon, copper alloy or higher Applicant: Seiko Epson Corporation

Claims (1)

[Claims] forming a metal mainly composed of aluminum as a first metal wiring layer above the semiconductor substrate; forming a metal mainly composed of copper as a second metal wiring layer on the first metal wiring layer; process, photo-etching the first
A method for manufacturing a semiconductor device, comprising: a step of forming a wiring pattern made of the second metal wiring layer; and a heat treatment step.