JPH03159127A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To prevent corrosion of wiring due to hydrogen chloride generated on a substrate by heating the semiconductor substrate after removing a photoresist film and a deposit film formed on side walls of a pattern at the time of dry etching. CONSTITUTION:An aluminum alloy film 2 containing silicon and copper is adhered to a semiconductor substrate 1, and a wiring is formed by dry-etching the aluminum alloy film 2 with a photoresist film 3 patterned on the aluminum alloy film 2. Then the photoresist film 3 is removed by oxygen plasma, and after a deposit film 4 formed on side walls of the pattern at the time of said dry etching is removed by organic peeling solution, the semiconductor substrate 1 is heated. Thus chlorine, aluminum chloride and moisture attaching to the semiconductor substrate surface can be sufficiently removed. Therefore no hydrogen chloride which may corrode the wiring is generated so that corrosion of fine wirings can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method of manufacturing a semiconductor device having aluminum wiring doped with copper and silicon.

[Prior Art] In recent years, in aluminum wiring technology for semiconductor integrated circuits, various types of migration have been confirmed to occur as circuits become more integrated. Therefore, in order to suppress the occurrence of this migration, a technology has been proposed in which semiconductor integrated circuit wiring is formed using an aluminum alloy to which a trace amount of copper is added, and this method has already been adopted as a mass production technology for semiconductor integrated circuits. It has been introduced. However, aluminum alloy (Af-8i-Cu alloy) containing trace amounts of silicon and copper
However, there are many problems in microfabrication of this into wiring. In particular, there is a drawback that the addition of copper tends to cause corrosion of aluminum alloy wiring. Furthermore, there are still many unknown points regarding the mechanism by which this corrosion occurs.

Next, A
A conventional method for manufacturing a semiconductor device using an f-8i-Cu alloy as a wiring material for a semiconductor integrated circuit will be described.

First, Af-8t-C having the above composition is deposited on the surface of a semiconductor substrate on which a diffusion layer, an insulating film, etc. have been formed by sputter deposition.
A u alloy is deposited to form an Ano5i-Cu alloy film.

Next, after forming a resist film on this Af-8i-Cu alloy film, a fine resist pattern is formed by photolithography. Then, by irradiating the entire surface of this semiconductor substrate with ultraviolet (UV) light, the resist film is cured and the dry etching resistance of the resist pattern is improved.

Next, using this resist pattern as a mask, the Af
-8i-Cu alloy film is dry etched to form a wiring pattern. In this case, as the dry etching gas, fluorocarbon gases such as CF4 and CHF3 are used to prevent side etching and corrosion of AI.
A mixed gas made by adding a small amount to a chlorine gas such as I2 is generally used.

Further, during this etching, deposited films or reaction products adhere to the pattern side surfaces of the resist film and the Af'-3i-Cu alloy film. Therefore, this Al-8
A strong oxide film is not formed on the side surfaces of the i-Cu alloy film. On the other hand, chlorine (Cf2) or aluminum chloride (AIC1'a) adheres to the surface of the semiconductor substrate during etching.
When reacts with atmospheric moisture (H20), hydrogen chloride (H20) is produced.
C)) is generated. Therefore, this hydrogen chloride corrodes the weak portions of the deposited film, and corrosion of the A-5i-Cu alloy film progresses due to a rapid electrochemical reaction.

To prevent such erosion, the semiconductor substrate is heated immediately after dry etching to evaporate chlorine and aluminum chloride into the atmosphere.

Next, the resist film is usually wet-stripped using a perforator-based Qll synergist, but if the resist film is hardened by dry etching or a deposited film is formed on the resist film surface, Since it is difficult to completely remove the resist film only by wet clearing using the remover, the semiconductor substrate is exposed to an oxygen plasma atmosphere, and the resist film on the substrate is removed by the oxygen plasma.

However, especially when dry etching is performed using a mixed gas of chlorine-based gas and fluorocarbon-based gas as described above, even if the resist film is peeled off by oxygen plasma, the outer periphery of the resist film and the pattern sidewalls may be removed. The deposited film attached to the surface tends to remain.

For this reason, by further treating the substrate after the oxygen plasma treatment with an organic stripping solution, the deposited film that has become susceptible to peeling off due to exposure to the oxygen plasma atmosphere is completely removed. In this way, the wiring of the semiconductor substrate is formed.

[Problems to be Solved by the Invention] However, in the conventional semiconductor device manufacturing method described above, after the resist film used as a mask for dry etching is removed using oxygen plasma, the resist film is removed using an organic stripper. When removing deposits attached to the outer periphery of the film and the pattern sidewalls, chlorine or aluminum chloride is generated from the interface between the pattern sidewalls of the Af-8i-Cu alloy film and the deposited film and from the deposited film itself. Then, this chlorine or aluminum chloride reacts with moisture in the atmosphere or moisture attached to the substrate during the stripping process to generate hydrogen chloride. This generation of hydrogen chloride causes corrosion of the aluminum alloy wiring. Furthermore, since the wiring may be disconnected due to such corrosion, the reliability of the semiconductor device is also significantly reduced.

The present invention has been made in view of such problems, and includes:
An object of the present invention is to provide a method for manufacturing a semiconductor device that can prevent corrosion of wiring due to hydrogen chloride generated on a substrate.

[Means for Solving the Problems] A method for manufacturing a semiconductor device according to the present invention includes a step of depositing an aluminum alloy film containing silicon and copper on a semiconductor substrate, and a photoresist patterned on the aluminum alloy film. A process of forming wiring by dry etching the aluminum alloy film using the film as a mask, a process of removing the photoresist film with oxygen plasma, and an organic peeling process of the deposited film formed on the side wall of the pattern during the dry etching. The method is characterized by comprising a step of removing with a liquid and a step of heating the semiconductor substrate.

[Operations] In the present invention, the semiconductor substrate is heated after removing the photoresist film and the deposited film formed on the sidewalls of the pattern during dry etching. Therefore, when the deposited film is peeled off, chlorine or aluminum chloride generated from the interface between the deposited film and the aluminum alloy film and from the deposited film itself,
Moisture adhering to the semiconductor substrate during peeling can be sufficiently removed. Therefore, the generation of hydrogen chloride that corrodes the wiring is prevented, so that corrosion of the fine aluminum alloy wiring can be prevented.

[Embodiments] Next, embodiments of the present invention will be described with reference to the accompanying drawings.

FIGS. 1(a) to 1(d) are cross-sectional views showing, in order of steps, a method for manufacturing a semiconductor device according to a first embodiment of the present invention.

First, as shown in FIG. 1(a), 1% by weight of silicon and 0.5% by weight of copper were added to the surface of a semiconductor substrate 1 on which a diffusion layer, an insulating film, etc. had been formed by sputter deposition. An aluminum alloy (Af-8i-Cu alloy) is deposited to form an Af-8i-Cu alloy film 2 having a thickness of about 1.0 μm. Next, (7) after forming a resist film 3 on the AI-8i-Cu alloy film 2, a fine resist pattern is formed by photolithography. Further, by irradiating the entire surface of the substrate with ultraviolet (UV) light, the resist film 3 is cured and the dry etching properties of the resist pattern are improved.

Next, as shown in FIG. 1(b), predetermined wiring is formed by dry etching the Af-8i-Cu alloy film 2 by RIE using the resist film 3 as a mask.

In this case, as the etching apparatus, for example, a batch type RIE apparatus is used, and as the dry etching gas,
IOsccM CHF, (fluorocarbon gas) 1100
A mixed gas added to 5CC of BCz3 and 50SCCM of C72 (chlorine-based gas) may be used. At this time,
For example, the pressure during etching is 20 to 40 mTorr.
The output of the high frequency power supply is 1kW.

Immediately after dry etching is completed, the semiconductor substrate is heated, for example, to about 200° C. for about 20 minutes in a nitrogen atmosphere. In fact, when a semiconductor device was heated under the above conditions, the wiring pattern formed on the semiconductor substrate was observed with an optical microscope, and it was found that AI! The -8t-Cu alloy film 2 was not corroded at all.

Next, as shown in FIG. 1C, the resist film 3 is removed by exposing the semiconductor substrate to an oxygen plasma atmosphere. This process of removing the resist film 3 can be carried out, for example, by loading the semiconductor substrate into a barrel-type plasma ashing device.
Oxygen flow rate is 2005CCM.

This can be done by exposing the semiconductor substrate to an oxygen plasma atmosphere for about 90 minutes at a pressure of 0.8 Torr.

After this step of removing the resist film 3 using oxygen plasma, the deposited film 4 that had adhered to the side wall of the resist film 3 remains on the Al-8i-Cu alloy film 2. In fact, when the semiconductor substrate was observed with an optical microscope after oxygen plasma treatment under the above conditions, the deposited film 4 remained on the outer periphery of the resist film 3.

Next, as shown in FIG. 1(d), this semiconductor substrate is immersed in a stripping solution for several minutes to remove the deposited film 4. Separate and remove.

Next, the semiconductor substrate from which the deposited film 4 has been removed is heated for 20 minutes under the same heating conditions as described above. As a result, aluminum alloy wiring is formed on the semiconductor substrate.

Moreover, when the semiconductor substrate was actually observed using an optical microscope after forming the aluminum alloy wiring through the above process, no corrosion was observed in the wiring pattern formed on the Af-8i-Cu alloy film 2. Furthermore, it was confirmed that the deposits and deposited film 4 on the side walls of the pattern were completely removed, and that the desired fine wiring pattern was formed.

Next, a second embodiment of the present invention will be described.

This example differs from the first example in terms of heat treatment conditions in the final step. In this example, the deposited film 4 on the Af-8i-Cu alloy film 2 attached to the side wall of the resist film 3 is
After peeling off, the semiconductor substrate is heated to 200° C. for about 20 minutes in a vacuum with a degree of vacuum of 1O-27 or J-.

According to the present embodiment, firstly, the same effects as in the embodiment are achieved, and by heating the inside of the heating device in a high vacuum state, when heating is performed in a nitrogen atmosphere as in the first embodiment. Moisture can be removed sufficiently and the heating time can be shortened.

Furthermore, in this example, when the semiconductor substrate was actually observed after forming the aluminum alloy wiring through the above process, no corrosion was observed in the wiring pattern formed on the A-5j-Cu alloy film 2. There wasn't. Furthermore, the deposits and deposited film 4 on the sidewalls of the pattern have been completely removed, and the desired ? It was confirmed that one thin wiring pattern was formed.

[Effects of the Invention] As explained above, according to the present invention, the semiconductor substrate is heated after removing the photoresist film during wiring pattern formation and the deposited film formed on the pattern sidewall during dry etching. Chlorine and aluminum chloride adhering to the surface as well as moisture can be sufficiently removed. Therefore, hydrogen chloride that corrodes the wiring is not generated, so that corrosion of fine wiring can be prevented.

Moreover, disconnection of wiring is also prevented, and a highly reliable semiconductor device can be manufactured.

[Brief explanation of the drawing]

FIGS. 1(a) to 1(d) are cross-sectional views showing, in order of steps, a method for manufacturing a semiconductor device according to a first embodiment of the present invention. 1; Semiconductor substrate, 2; Af-8i-Cu alloy film, 3; Resist film, 4; Deposited film

Claims (1)

[Claims] (1) Wiring is formed by depositing an aluminum alloy film containing silicon and copper on a semiconductor substrate, and dry etching the aluminum alloy film using a photoresist film patterned on the aluminum alloy film as a mask. a step of removing the photoresist film with oxygen plasma, a step of removing a deposited film formed on the sidewall of the pattern during the dry etching with an organic stripping solution, and a step of heating the semiconductor substrate. A method for manufacturing a semiconductor device, characterized in that: