JPH0436485A - Production of semiconductor device - Google Patents

Abstract

PURPOSE:To satisfactorily remove residual Cl on a semiconductor substrate and to prevent after-corrosion by dry-etching a thin Al or Al alloy film on the substrate with chlorine-contg. gases in a reaction chamber, and removing a resist with gaseous oxygen in other reaction chamber. CONSTITUTION:An SiO2 film 2 and an Al alloy film 3 are grown on a semiconductor substrate 1 and a photoresist 4 is formed on the film 3. This film 3 is subjected to reactive ion etching with a gaseous SiCl4-Cl2 mixture through a pattern of the photoresist 4 as a mask in a first reaction chamber. The substrate 1 is then transferred to a second reaction chamber in vacuum, and not only the photoresist 4 but also adsorbed residual chlorine 6 is removed with plasma of gaseous O2. The substrate is finally heated to >=200 deg.C and held for about 3min to evaporate and remove residual Cl.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a post-treatment method for dry etching thin films of aluminum or aluminum-containing alloys.

BACKGROUND OF THE INVENTION Aluminum or aluminum-containing alloys are used as wiring materials for semiconductor devices. Furthermore, as LSIs become more highly integrated, finer wiring patterns are also required. Therefore, anisotropic dry etching of aluminum or aluminum-containing alloy films has been carried out. Conventionally, in anisotropic dry etching of aluminum or aluminum-containing alloy films, B C13
, S i C14, CC14, and a mixture of C12 gas (hereinafter referred to as chlorine-based gas) is used as the etching gas. In this dry etching of aluminum or aluminum-containing alloy films using chlorine-based gas, if the substrate is taken out into the atmosphere without post-treatment after etching and left unattended, the problem arises that the aluminum wiring will break. However, the reliability of the wiring deteriorates. This is because residual chlorine on the substrate combines with moisture in the atmosphere to form MCI, which dissolves aluminum and the like (after-corrosion).

As a countermeasure for this problem, as a post-processing method, the substrate is taken out into the atmosphere and immediately washed with water, the substrate is subjected to CF4 plasma treatment and then taken out into the atmosphere, and the resist is processed at a relatively low temperature (below 100°C). A method is used in which the substrate is taken out into the atmosphere after a removal process.

Problems to be Solved by the Invention However, in the conventional post-processing method described above, the after-corrosion
This is insufficient as a countermeasure against John. In other words, with the method of washing with water, aftercorrosion occurs even in a short period of time from when the substrate is taken out into the atmosphere until it is washed with water.
In the resist removal processing method at temperatures below 0 DEG C., residual chlorine on the substrate cannot be completely removed, resulting in the problem of after-corrosion.

The present invention solves the above problems, and makes it possible to effectively remove residual chlorine on a substrate in dry etching of aluminum or aluminum-containing alloy films using chlorine-based gas, thereby preventing after-corrosion. It is an object of the present invention to provide a method for manufacturing a semiconductor device that can prevent the occurrence of such problems.

Means for Solving the Problems In order to solve the above problems, in the method for manufacturing a semiconductor device of the present invention, an etching apparatus having at least two plasma reaction chambers is used for dry etching a thin film of aluminum or an aluminum-containing alloy on a semiconductor substrate. using
After performing dry etching using a chlorine-based gas in a first reaction chamber using a photoresist pattern as a mask, the semiconductor substrate is transported in a vacuum to a second reaction chamber different from the first reaction chamber. In the reaction chamber, a resist removal process using plasma using oxygen gas and a process of heating the semiconductor substrate to a temperature of 200° C. or higher are performed.

In a second invention, a mixed gas of oxygen gas and fluorine gas is used in the plasma resist removal process of the first invention.

Furthermore, a third aspect of the present invention is to perform plasma treatment using a fluorine-based gas in the second reaction chamber before the resist removal process using plasma according to the first aspect.

Operation According to the manufacturing method of the first invention described above, after dry etching the aluminum or aluminum-containing alloy thin film on the semiconductor substrate using a chlorine-based gas in the first reaction chamber using the photoresist pattern as a mask, , perform the following post-processing.

That is, this semiconductor substrate is transported in a vacuum, and a resist removal process using plasma is first performed in a second reaction chamber different from the first reaction chamber.

It is known that a considerable amount of residual chlorine, which causes after-corrosion, exists on or inside the resist used as a mask. therefore,
This resist removal process reduces the amount of residual chlorine that causes after-corrosion, and then by heating the semiconductor substrate to a temperature of 200°C or higher, it is possible to reduce the amount of residual chlorine that remains on the substrate surface. The chlorine present will evaporate and be removed.

Therefore, occurrence of after-corrosion is prevented.

Furthermore, by performing plasma treatment using fluorine-based gas according to the manufacturing method of the second or third invention, residual chlorine (Cl3) on the wafer surface can be converted to fluorine (F)!
replaced and removed. Therefore, chlorine (Cρ) remaining on the wafer surface is more effectively removed, and after-corrosion is prevented from occurring.

EXAMPLE Hereinafter, an example of the present invention will be described with reference to the drawings.

First Embodiment FIGS. 1A to 1D are cross-sectional views of a semiconductor device sequentially showing a first embodiment of the method for manufacturing a semiconductor device of the present invention.

First, in FIG. 1(a), a silicon dioxide (S102) film 2 is formed on a semiconductor substrate 1, and then an Al-3t (1%)-Cu film with a thickness of 0.8 μm is formed on the silicon dioxide (S102) film 2. (0,
5%) Film 3 is grown by sputtering. Thereafter, a pattern of the photoresist 4 is formed using a known photolithography technique.

Next, in the first reaction chamber of the etching apparatus, the etching process shown in FIG.
), using the pattern of the photoresist 4 as a mask, reactive ion etching (RIE) is performed using a mixed gas of SiC14 and 01□ as an etching gas, patterning is performed, and Al-5i (1%)- Cu(0,5
%) Wiring pattern 5 is obtained. At this time, some chlorine (C1) remains on the wafer. It is known that this residual chlorine (CI) 6 mainly exists on the surface and inside of the photoresist 4 and on the side wall surface of the wiring pattern 5.

Next, the etched wafer is transported in vacuum to a second reaction chamber different from the first reaction chamber, and as shown in FIG. 1(C), it is processed in plasma using 02 gas. Photoresist 4 is removed. At this time, the temperature of the wafer is maintained at 100° C. or less, and the photoresist 4 is removed, and residual chlorine (CI>6) adsorbed on the surface and inside of the photoresist 4 is also removed.

Finally, as shown in Figure 1(d), the temperature of the wafer is increased to 25°C.
The wafer is heated to 0° C. and held for 3 minutes, where heating is performed from the back side of the wafer with a halogen lamp heater.

By this heating, chlorine (C1) still remaining on the wafer surface can be evaporated and removed.

Thus, according to this example, Al-5t(1%)-
After dry etching the Cu (0.5%) film 3, chlorine (CI>6) remaining on the wafer surface can be effectively removed, and the occurrence of after-corrosion can be prevented.

In this example, the heating temperature of the last wafer was set to 25
The heating temperature of the wafer was 200°C to 300°C.
A similar effect can be obtained if the temperature is within the range of °C. In addition, the heating time may be at least 1 minute or more, and may be set at an appropriate time taking into consideration the heating temperature.
When heated above 0°C, Al-8t(1%)-Cu(0
, 5%) Problems such as deterioration of the film of the wiring pattern 5 occur.

In addition, in this example, the photoresist removal process was performed in plasma using 02 gas, but the photoresist removal process was performed in plasma using a mixed gas of 0□ gas and a fluorine-based gas such as CF, CHF, SF, etc. In that case, chlorine (C1) and fluorine (F) are also replaced, so the chlorine (C1) remaining on the wafer surface is
)6 can be removed more effectively.

Further, in this embodiment, the wafer was heated after the photoresist removal process using plasma, but the photoresist removal process using plasma may be performed simultaneously with the heating of the wafer.

Furthermore, in this example, the photoresist removal process using plasma and the heating process of the wafer were performed in the same second reaction chamber, but after the photoresist removal process using plasma, the wafer was transferred to another vacuum chamber. The wafer may be transferred to a reaction chamber and subjected to heat treatment. In this case, heating can be performed from the front or back side of the wafer using, for example, a halogen lamp heater.

Furthermore, in this example, Al-
31-Cu film was selected, but aluminum metal (A1) film, Al-3i, Al-Cu, Al-8i, Al
- Dry dry aluminum-containing aluminum alloy film such as 3t-Ti.
A similar result can be obtained by soching.

Second Embodiment FIGS. 2A to 2F are cross-sectional views of a semiconductor device sequentially showing a second embodiment of the method for manufacturing a semiconductor device of the present invention.

Note that the same components as those in FIG. 1 are given the same reference numerals.

First, as shown in FIG. 2(a), similar to FIG. 1(a), a SiO□ film 2 with a thickness of 0.8 μm is placed on a semiconductor substrate 1
Al-3t(1%)-Cu(0.5%)! ! ! 3 are formed one after another, and a photoresist 4 is formed into a pattern.

Next, in the first reaction chamber of the etching apparatus, the etching process shown in FIG.
), as shown in FIG. 2(b), using the pattern of photoresist 4 as a mask, SiC14 and 01
Perform reactive ion etching (RIE) using the mixed gas of □ as the etching gas), buttering, and
-3t (1%) -Cu (0.5%) wiring pattern 5 is obtained. During this process, chlorine (C1) still remains on the wafer. This residual chlorine (C1) 6 mainly exists on the surface and inside of the photoresist 4 and on the side wall surface of the wiring pattern 5.

Next, the etched wafer is transported in vacuum to a second reaction chamber different from the first reaction chamber.
As shown in Figure (C), plasma treatment using CF and gas is performed. As a result, most of the residual chlorine (CI) 6 on the wafer surface is replaced with fluorine (F) and removed.

Next, as shown in FIG. 2fd), processing is performed in plasma using O2 gas to remove the photoresist 4. At this time, the temperature of the wafer is kept below 100°C. When the photoresist 4 is removed, residual chlorine (C1) 6 adsorbed on the surface and inside of the photoresist 4 is also removed.

Finally, as shown in Figure 2(e), the temperature of the wafer is increased to 25%.
The wafer is heated to 0° C. and held for 3 minutes, where heating is performed from the back side of the wafer with a halogen lamp heater.

By this heating, chlorine<CI)6 still remaining on the wafer surface can be evaporated and removed.

Thus, according to this example, Al-8i (1%)-
After dry etching the Cu (0.5%) film 3, chlorine (CI) 6 remaining on the wafer surface can be effectively removed, and after-corrosion can be prevented from occurring.

Note that in this example, the heating temperature of the wafer after ij & was set at 250°C, but the heating temperature of the wafer was set at 200°C to 3°C.
A similar effect can be obtained if the temperature is in the range of 00°C. Further, the heating time may be at least 1 minute or more, and may be set to an appropriate time in consideration of the heating temperature.

In addition, in this example, plasma treatment using CF gas was performed prior to photoresist removal treatment, but CF4
Instead of , a fluorine-based gas such as CHF, , SF, etc. may be used.

In addition, in this example, the photoresist removal process was performed in a plasma using 02 gas, but the photoresist removal process was performed in a plasma using a mixed gas of 02 gas and a fluorine-based gas such as CF, CHF, SF6, etc. In that case, chlorine (C1) and fluorine (F) are also replaced, so the chlorine (CI) remaining on the wafer surface is
6 can be removed more effectively.

Further, in this embodiment, the wafer was heated after the photoresist removal process using plasma, but the photoresist removal process using plasma may be performed simultaneously with the heating of the wafer.

In addition, in this example, the photoresist removal process using plasma and the wafer heat treatment were performed in the same second reaction chamber, but after the photoresist removal process using plasma, the wafer was subjected to another reaction in a vacuum. The wafer may be transferred to a chamber for heat treatment; in this case,
Heating can be performed from the front or back side of the wafer using, for example, a halogen lamp heater.

Furthermore, in this example, Al-
3i-Cu film was selected, but aluminum metal (AI) W
A, or Al-3i, Al-Cu, Al-5t, A
Similar results can be obtained when dry etching an aluminum-containing alloy film such as l-3i-Ti.

Effects of the Invention As described above, according to the present invention, in dry etching a thin film of aluminum or an aluminum-containing alloy on a semiconductor substrate, an etching apparatus having at least two plasma reaction chambers is used, and a photoresist is etched in the first reaction chamber. - After performing dry etching using a chlorine gas using the pattern as a mask, the semiconductor substrate is transported in a vacuum, and oxygen gas is used in a second reaction chamber different from the first reaction chamber. By performing a resist removal process using a hot plasma and a process of heating the semiconductor substrate to a temperature of 200°C or higher, residual chlorine on the substrate can be effectively removed in dry etching of an aluminum or aluminum-containing alloy film using a chlorine-based gas. This makes it possible to remove it immediately, thereby preventing the occurrence of after-corrosion.

Therefore, it becomes easy to process aluminum or aluminum-containing aluminum, and it is possible to achieve a great effect in further increasing the degree of integration of LSIs.

Further, according to the second or third invention, residual chlorine on the wafer surface is replaced with fluorine and removed by performing plasma treatment using fluorine-based gas, so that residual chlorine can be removed more effectively. This makes it possible to remove after-corrosion and prevent the occurrence of after-corrosion.

[Brief explanation of drawings]

FIGS. 1(a) to 1(fd) are cross-sectional views of a semiconductor device sequentially showing a first embodiment of the method for manufacturing a semiconductor device of the present invention, and FIG. 1A to 2E are cross-sectional views of a semiconductor device sequentially showing a second embodiment of the method for manufacturing a semiconductor device of the present invention. 1... Semiconductor substrate, 2... Silicon dioxide (Sin
□) Film, 3--AI-81-Cu film, 4... Photoresist, 5... Al-81-Cu wiring pattern, 6
...Residual chlorine (C1). Fig. f Fig. 1 (At-57-Gukllbft-y6) Fig. 2 (Tsubuki) )

Claims (1)

[Claims] 1. In dry etching of aluminum or an aluminum-containing alloy thin film on a semiconductor substrate, an etching apparatus having at least two plasma reaction chambers is used, and a photoresist pattern is used as a mask in the first reaction chamber. After performing dry etching using chlorine-based gas, the semiconductor substrate is transported in a vacuum, and the resist is removed by plasma using oxygen gas in a second reaction chamber different from the first reaction chamber. A method of manufacturing a semiconductor device, comprising performing a treatment and a treatment of heating the semiconductor substrate to a temperature of 200° C. or higher. 2. The method of manufacturing a semiconductor device according to claim 1, wherein a mixed gas of oxygen gas and fluorine gas is used in the resist removal process using plasma. 3. The method of manufacturing a semiconductor device according to claim 1, further comprising performing plasma treatment using a fluorine-based gas in the second reaction chamber before the resist removal process using plasma.