JP2004087744A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a resist mask removing method with higher yield in the wiring forming process in which an insulation film including carbon elements is used. <P>SOLUTION: A resist mask can be removed by using a plasma of mixed gas in which a rare gas is added to hydrogen and applying a high frequency bias to a semiconductor substrate. Accordingly, the practical resist removing velocity can be attained in the mass-production system without any problems of variation in quality and side etching of insulation film, and insufficient exposure in the lithography process. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a semiconductor device manufacturing technique, and more particularly to a step of removing a resist film.
[0002]
[Prior art]
In the field of semiconductor manufacturing, a resist film is formed on a main surface of a semiconductor substrate as a mask for forming a pattern of a lower conductive film or an insulating film.
As a method for removing the resist film, a method using oxygen plasma is very common. In addition, a method of applying a bias to a sample to obtain anisotropy and treating with a plasma of a gas in which nitrogen is mixed with oxygen, a method of treating with a plasma of a gas in which nitrogen and hydrogen are mixed, and a method of treating with a plasma of ammonia gas A method of processing, a method of processing with plasma of only hydrogen, and the like are being studied.
[0003]
[Problems to be solved by the invention]
In the process of manufacturing a semiconductor device, it is expected that a low dielectric constant film containing a carbon element will be used as an insulating material between wirings within several years.
In such a process, a technique for removing the resist of the mask material from the low-dielectric-constant film after etching without dimensional change or deterioration is required.
After the removal of the resist, a mask is formed again by lithography. Since lithography is a technique using a catalytic reaction with a trace amount of acid, a resist removing method is required in which an alkaline base such as NH4 + that inhibits this is not generated in the low dielectric constant film.
Further, since the resist of about 150 nm to 300 nm remains after the removal of the low dielectric constant film, a resist removal rate of at least 100 nm / min or more is required from the viewpoint of throughput. In response to these requirements for resist removal, conventional processing using plasma of oxygen gas or plasma of mixed gas of oxygen and nitrogen has a problem of causing side etching and alteration in a low dielectric constant film containing a carbon element.
In addition, in the case of processing using a mixed gas of hydrogen and nitrogen or plasma of ammonia, an alkaline base of NH4 + is generated in the low dielectric constant film, which causes a problem of causing exposure failure. Further, there is a problem that a sufficient etching rate cannot be obtained by the plasma treatment using only hydrogen.
The present invention provides a method of removing a resist mask applicable to mass production in a semiconductor manufacturing process using a low dielectric constant film containing a carbon element.
[0004]
[Means for Solving the Problems]
A plasma of a mixed gas obtained by adding a rare gas to hydrogen is used, and a high-frequency bias is applied to the sample.
[0005]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
Using a plasma of a mixed gas of (1) hydrogen and neon, (2) hydrogen and argon, and (3) hydrogen and krypton, removal of the resist from the sample to which a high-frequency bias of 0.5 W / cm 2 was applied was examined. . As a sample (semiconductor substrate), a sample obtained by forming a resist mask having a hole pattern on a low dielectric constant film containing carbon element (MSQ) and etching the MSQ in accordance with the hole pattern was used.
FIG. 1 shows the relationship between the plasma resist removal rate of each mixed gas and the rare gas addition rate. With the addition of neon having a small mass number, a high etching rate cannot be obtained even if a gas is added. It was found that a high removal rate can be obtained by adding argon or krypton having a large mass number.
The reason why a high removal rate can be obtained by adding argon or krypton is that a resist removal reaction by hydrogen radicals is promoted by irradiating a sample with ions of a rare gas having a large mass number accelerated by a high frequency bias. I understand.
In addition, it was found that, due to this mechanism, a higher resist removal rate can be obtained with a higher density plasma in which more hydrogen radicals and rare gas ions are produced.
In addition, it was confirmed that a vertical shape can be obtained by any method after removing the resist.
(Example 2)
FIG. 2 shows an example in which the resist removing method of the present invention is applied to a multilayer wiring process of a semiconductor device. In this wiring process, (1) formation of SiC film by chemical vapor deposition method (CVD method) (2) deposition of MSQ by spin coating method (SOD method) (3) formation of SiON on MSQ (4) lithography (5) Via holes are formed in the MSQ by etching SiON and MSQ by plasma of a CHF-based gas along the resist mask. FIG. 3 shows a cross-sectional view of the process at this time. 1 is a semiconductor substrate, 2 is a SiC film, 3 is an MSQ film, 4 is SiON, and 5 is a resist mask. Next, (6) the resist is removed by the mixed gas plasma of hydrogen and krypton described in Example 1, and (7) a trench pattern is formed again by lithography. (8) SiON by plasma of CHF-based gas along the resist mask. And etching of the MSQ forms a hole and trench structure. FIG. 4 shows a process sectional view at this time.
(9) After the removal of SiC, (10) the remaining resist mask is removed, and (11) a Cu diffusion prevention film Ta, a TaN layer and a plating seed layer Cu are sequentially formed on the hole and trench structures by sputtering. I do. (12) Thereafter, Cu is embedded by plating. Next, the excess Cu and the diffusion preventing film deposited on the surface of the MSQ in the embedding process are removed together with the upper layer of SiON by (13) chemical mechanical polishing (CMP), and (14) cleaning with a chemical solution is performed.
The washed sample is repeatedly processed in order from the CVD in the step (1) again to form a multilayer wiring. The yield of the semiconductor device manufactured by this manufacturing method using the addition of the mixed gas of hydrogen and krypton in the resist removing step (6) was 90%. On the other hand, in the case of using the plasma of the mixed gas of nitrogen and hydrogen in the step (6), the yield was reduced to 50% due to exposure failure in the lithography step of (7). Further, when gas plasma containing oxygen was used in the resist removal step (6) or (10), the MSQ was altered and the high frequency characteristics were significantly deteriorated.
As described above, in a semiconductor manufacturing process using an insulating film containing a carbon element, a highly reliable semiconductor device can be manufactured by using plasma of a mixed gas of hydrogen and a rare gas when removing a resist mask. it can.
[0006]
【The invention's effect】
By using the manufacturing process of the semiconductor device of the present invention, a highly reliable semiconductor device can be manufactured.
[Brief description of the drawings]
FIG. 1 is a characteristic diagram showing a resist removal rate when plasma of a mixed gas of hydrogen and a rare gas is used.
FIG. 2 is a flowchart showing a multilayer wiring step of a semiconductor device to which the etching method of the present invention is applied.
FIG. 3 is a cross-sectional view illustrating a manufacturing process of the semiconductor device of the present invention.
FIG. 4 is a sectional view showing a manufacturing process of the semiconductor device of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Semiconductor substrate, 2 ... SiC film, 3 ... MSQ film, 4 ... SiON, 5 ... Resist mask.

Claims (2)

Manufacturing of a semiconductor device including a step of depositing an insulating film containing a carbon element on a main surface of a semiconductor substrate, a step of forming a resist mask using lithography, a step of etching the insulating film, and a step of removing the resist mask A method of manufacturing a semiconductor device, comprising removing the resist mask using plasma of a mixed gas containing both a hydrogen gas and a rare gas. 2. The method according to claim 1, wherein the rare gas is krypton.

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