JPS5841766B2 - Manufacturing method of semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method suitable for manufacturing a semiconductor device having aluminum-copper alloy electrodes and wiring.

In recent years, pure aluminum, aluminum-silicon alloys, titanium-based aluminum, etc. can all be patterned using reactive sputter etching equipment with parallel plate electrodes.

However, it is difficult to use aluminum-copper alloys alone, and there are still almost no examples of practical use.

Generally, when sputtering and etching aluminum and copper alloys, B C73, CC74°P is used as an etchant.
Cl3. A gas such as BBr3 is used.

In that case, the aluminum reacts with the gases and becomes chloride or bromide and is etched away, but the copper does not do so and remains, becoming increasingly concentrated.

Therefore, the remaining copper is etched if HNO3
It is necessary to remove it with liquid No. 11 or the like.

However, when aluminum/copper alloy is etched as described above, Cl, Br, etc. are trapped in the steel or in the form of Cu CIXp Cu Br rx, so they are taken out into the atmosphere. The presence of moisture produces HCA, HBr, etc., and the patterned aluminum-copper alloy is rapidly corroded, to the extent that there is no time to wash it with water, for example.

Very recently, it has been announced that aluminum-copper alloys can be sputter etched in an atmosphere at a temperature of 250 degrees Celsius.

In this case, it is not possible to use a photo resist as a patterning mask due to the temperature, so it is considered necessary to use, for example, a phosphosilicate glass film, a sputtered oxide film, an alumina film, etc. as a mask. is certain to increase.

As exemplified above, regarding sputter etching of aluminum/copper alloys, it seems that a technology that can be easily implemented in a mass production process has not yet been established, but in this way, it is desirable to use aluminum/copper alloys. This is largely due to its excellent electromigration resistance.

In other words, the electromigration resistance of aluminum-copper alloy is 10 times higher than that of aluminum.
There are more than 0 times.

Therefore, even if formed into a fine pattern, a large current can flow, making it suitable for use as electrodes and wiring for semiconductor devices that require large currents, such as bipolar transistors. It is effective when converting

For the reasons mentioned above, aluminum and copper alloys are used as electrodes.
When using it as a wiring material, the main aim is to create a fine pattern, so it is difficult to apply the wet etching method, which has a practical limit of [2μ door], even on a laboratory scale.

In addition, the lift-off method, which is more advantageous in forming fine patterns than the wet etching method, is prone to breakage if the surface of the substrate has sharp steps, and cannot be heat treated to improve adhesion to the substrate. The scope of application is quite limited.

Therefore, there are great expectations for the reactive sputter etching method in patterning aluminum/copper alloys.

The present invention applies a reactive sputter etching method to patterning an aluminum/copper alloy, thereby making it possible to extremely easily form electrodes and interconnections with fine patterns, which will be described in detail below.

In the present invention, it is required that the aluminum/copper alloy film be patterned under normal conditions using a conventional parallel plate electrode type reactive sputter etching device as shown in the figure, and then exposed to hydrogen gas plasma in the same device. It has become.

In the figure, 1 is a reaction chamber, 2 is a water-cooled high-frequency electrode, 3 is a ground electrode, 4 is a high-frequency power source, 5 is a semiconductor sea urchin..., 1a
1b shows a reaction gas inlet pipe, and 1b shows an exhaust pipe.

We conducted experiments on patterning aluminum and copper alloys using such a device, and obtained the following results.

Perform etching as described above, a) Part 1
When I took it out, I found a patterned aluminum
The copper alloy corroded rapidly, causing wire breakage, but
(Torr), 200 (W) hydrogen plasma for 5 minutes and then removed, copper remained but no corrosion occurred.

Therefore, after the treatment as described in ), the remaining copper was removed by immersing it in concentrated nitric acid for about 30 seconds, and the desired aluminum-copper alloy pattern could be obtained.

As mentioned above, the reason why corrosion does not occur when aluminum-copper alloy is exposed to hydrogen plasma after patterning is not fully understood, but the cause of corrosion is
When the etchant components and copper compounds come into contact with the atmosphere, hydrochloric acid (
Hydrogen plasma reduces etchant components and copper compounds, such as copper chloride, to copper and eliminates the source of hydrochloric acid. It is thought that it acts as a cutoff.

In any case, after the hydrogen plasma treatment, there is sufficient room for washing with water or removing copper by fermentation in the atmosphere.

Similarly, only hydrogen was effective for plasma, and oxygen, argon, etc. were not effective.

As can be seen from the above description, according to the present invention, when patterning an aluminum/copper alloy using a reactive sputter etching device, after patterning according to a conventional technique, hydrogen plasma is applied in the same device. By exposing the aluminum/copper alloy to the atmosphere, it is possible to prevent the aluminum/copper alloy from corroding even if the sea urchin is taken out into the atmosphere, so it can be applied when miniaturizing the electrodes and wiring of semiconductor devices that require large currents. It is valid.

Furthermore, in carrying out the present invention, only a hydrogen plasma bath process is added to the conventional sputter etching process, and this can also be done by switching the gas fed into the apparatus, so the process intensifier port is It's like nothing.

[Brief explanation of the drawing]

The figure is an explanatory diagram showing an example of a device implementing the present invention. In the figure, 1 is the reaction chamber, 2 is the electrode, 3 is the ground electrode, and 4
is a high frequency power supply, 5 is a wafer, 1a is a reaction gas feed pipe, 1
b is an exhaust pipe.

Claims (1)

[Claims] 1. A semiconductor wafer on which an aluminum/copper alloy film is formed is set in a reactive sputter etching device, and the aluminum/copper alloy film is patterned,
Next, a method for manufacturing a semiconductor device, comprising the step of generating hydrogen plasma in the same apparatus and bathing the patterned aluminum/copper alloy film.