JPH09270420A - Manufacture of semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of photoresist remnants by efficiently removing a resist deterioration layer in a manufacturing method of a semiconductor device performing dry etching of a conductive layer by using a gas containing bromine or the like. SOLUTION: At the time of performing an etching process on a conductive film 3 formed on a semiconductor substrate 1 by using gas containing bromine, a photoresist 4 is applied on the conductive film 3 so as to perform etching of the conductive film 3 while having the photoresist 4 as a mask. Thereafter, a semiconductor wafer is washed by using a diluted fluoric acid water to remove a resist deterioration layer 5 followed by performing ashing for removing the photoresist.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device including a step of etching a conductive film,
In particular, the present invention relates to a method for manufacturing a semiconductor device in which contaminants and photoresist generated by etching are removed from the semiconductor device.

[0002]

2. Description of the Related Art In fine processing of a semiconductor device, for example, when processing a polycrystalline silicon film into a gate electrode shape, a bromine-based gas is used to coat a photoresist on the polycrystalline silicon film and mask the photoresist. In some cases, the polycrystalline silicon film is plasma-etched by the photolithography method. In the case of dry etching using a bromine-based gas, a compound of bromine and carbon is generated on the surface layer of the photoresist by the etching, and even if ashing treatment with oxygen plasma is performed to remove the photoresist, this compound is masked. As a result, the photoresist under the deposit cannot be completely removed, and a resist residue is likely to be generated.

As a method of manufacturing a semiconductor device for surely removing a photoresist, Japanese Patent Application Laid-Open No. 4-96329 discloses a method of cleaning and removing with an ammonia hydrogen peroxide solution.

[0004]

However, Japanese Unexamined Patent Publication No. 4-9.
In the method of removing using ammonia hydrogen peroxide solution described in Japanese Patent No. 6329, cleaning must be performed for a long time in order to have an effective removing effect. In this case, the photoresist is stripped by the ammonia hydrogen peroxide solution, and the stripped photoresist floats in the cleaning tank, so that a large amount of particles are generated. Then, the ammonia hydrogen peroxide solution is contaminated by the particles and cannot be used as a cleaning chemical liquid, so that it is necessary to replace the ammonia hydrogen peroxide solution with clean ammonia hydrogen peroxide solution, and the cost increases.

Therefore, in the conventional manufacturing method, in order to suppress the generation of particles, a cleaning treatment with ammonia hydrogen peroxide solution for a short time is performed before ashing, then ashing is performed, and then ammonia hydrogen peroxide solution is again used. Since cleaning is performed, there is a problem in that the number of processes increases and the throughput decreases.

Therefore, it is an object of the present invention to provide a method for manufacturing a semiconductor device with high throughput, which can surely remove the etching product and the photoresist on the surface layer of the photoresist with a small number of steps.

[0007]

The present invention is a method for manufacturing a semiconductor device, wherein a conductive film formed on a semiconductor substrate is etched by using a gas containing bromine, and a resist pattern is formed on the conductive film. A first step of etching the conductive film with a gas containing bromine using the resist pattern as a mask, and a second step of cleaning the semiconductor substrate with dilute hydrofluoric acid water after the first step. And a third step of performing ashing after the first step.

In one aspect of the present invention, the third step is performed after the second step.

In one aspect of the present invention, the method further comprises the fourth step of performing the second step after the third step, and washing the semiconductor substrate with sulfuric acid after the second step.

In one aspect of the present invention, the concentration of hydrofluoric acid in the dilute hydrofluoric acid water is in the range of 0.05 to 0.3%.

In one aspect of the present invention, a fifth step of performing plasma ashing using a gas containing CF ₄ and O ₂ after the first step, and an O ₂ gas after the fifth step The method further includes a sixth step of performing plasma ashing using.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of a method for manufacturing a semiconductor device according to the present invention will be described below with reference to FIG. FIG.
FIG. 6A is a cross-sectional view for each step showing a method for manufacturing a semiconductor device according to an embodiment.

First, as shown in FIG. 1A, an insulating film 2 having a film thickness of about 30 Å or more is formed on a Si substrate 1, and a high concentration n-type polycrystalline Si film 3 is formed on the insulating film 2 by a known CVD method. Chemical
Vapor Deposition) method, a photoresist is applied on the polycrystalline silicon film 3 to form a resist pattern 4 by a known photolithography method, and dry etching is performed using HBr gas using the resist pattern 4 as a mask. Then, the wiring of the polycrystalline silicon film 3 is formed. This dry etching is performed in a parallel plate type plasma etching apparatus, for example, in three stages described below.

The etching conditions when using this etching apparatus are, for example, CF ₄ 100 ccm in the first step,
Processing pressure 700mTorr, RF power 300W, 2nd
In the stage, HBr ₂₀ ccm, Cl ₂ 200 ccm, processing pressure 400 mTorr, RF power 250 W, and in the third stage HBr 200 ccm, Cl ₂ 100 ccm,
The processing pressure is 400 mTorr and the RF power is 200 W.

Here, in the first step, the dry etching of the polycrystalline silicon film 3 using HBr has a very high selectivity ratio to the silicon oxide film and it is difficult to remove the natural oxide film on the surface of the polycrystalline silicon film 3. The etching is performed to remove the natural oxide film in advance. The second step is main etching and the third step is over-etching. At this time, an altered layer 5 made of C, Si and Br is formed on the resist surface. Although the parallel plate plasma etching apparatus is used in the present embodiment, the present invention is also applicable to an etching apparatus using electron cyclotron resonance (ECR) plasma or inductively coupled (ICP) plasma.

Next, the semiconductor wafer after the above-mentioned etching is washed with dilute hydrofluoric acid adjusted to H ₂ O: HF = 100: 1 and 23 ° C. The cleaning conditions at this time are as follows, for example. First, the chemical solution is used for washing for 1 minute, followed by washing with water for 5 minutes and then ordinary spin dryer drying. Further, since the etching rate of the thermal oxide film of the chemical solution is 3 to 4Å / min, the insulating film 2
There is no need to worry about scraping. By performing such diluted hydrofluoric acid cleaning, as shown in FIG. 1B, the altered layer 5 formed during the etching is almost removed.

Subsequently, as shown in FIG. 1C, the cleaned semiconductor wafer is ashed by a normal microwave plasma asher (not shown) in the following two stages. The respective ashing conditions in the first stage and the second stage at this time are as follows, for example. The first stage CF ₄ 10 ccm O ₂ 200 ccm microwave power 800W processing pressure 0.8Torr processing time 10sec second phase O ₂ 200 ccm microwave power 800W processing pressure 0.8Torr processing time 60sec

In the first step of the ashing conditions, the removal of the deteriorated layer 5 which was incomplete by the diluted hydrofluoric acid cleaning becomes complete,
The resist can be removed efficiently in the second stage.

However, incomplete removal of the resist by cleaning with dilute hydrofluoric acid occurs only when there is a pattern having a very large resist coating area on the semiconductor wafer. If there is no such pattern, the first step of ashing is performed. Can be deleted.

FIG. 2 shows a process flow of this embodiment.
Since there is a possibility that organic substances of a size that cannot be observed by SEM (scanning electron microscope) may remain on the surface of the semiconductor wafer, when the subsequent process is, for example, a film formation process by the LP-CVD (low pressure chemical vapor deposition) method. It is desirable to wash with sulfuric acid / hydrogen peroxide after ashing. On the other hand, when the subsequent step is an ion implantation step or the like, the above-mentioned contamination does not cause any particular problem, and therefore the sulfuric acid / hydrogen peroxide washing need not be performed.

In the present embodiment, the case of etching the high-concentration polycrystalline silicon film has been described, but any film that can be etched with a bromine-based gas may be used. Further, in the present embodiment, the ashing is performed after the diluted hydrofluoric acid cleaning, but the diluted hydrofluoric acid cleaning may be performed after the ashing.

[0022]

As described above, in the present invention,
Using a gas containing bromine for the semiconductor element, in the production of a semiconductor device dry-etching, before ashing, since the degeneration of the photoresist surface is removed by cleaning with a chemical solution that does not cause peeling of the photoresist, It is possible to realize a method of manufacturing a semiconductor device in which the deteriorated substance serves as a mask and a resist residue is not generated during ashing, and the photoresist can be reliably removed in a small number of steps.

[Brief description of drawings]

FIG. 1 is a cross-sectional view for each step for explaining an embodiment of the present invention.

FIG. 2 is a flowchart showing steps of a method for manufacturing a semiconductor device according to an embodiment of the present invention.

[Explanation of symbols]

 1 Silicon substrate 3 Polycrystalline silicon film 4 Photoresist 5 Resist alteration layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location G03F 7/42 G03F 7/42 H01L 21/027 H01L 21/304 341M 21/304 341 21/30 572A

Claims (5)

[Claims] 1. A method of manufacturing a semiconductor device in which a conductive film formed on a semiconductor substrate is etched by using a gas containing bromine, wherein a resist pattern is formed on the conductive film and the resist pattern is used as a mask. A first step of etching the conductive film with a gas containing bromine; a second step of cleaning the semiconductor substrate with dilute hydrofluoric acid water after the first step; and the first step. And a third step of performing ashing after that. 2. The method of manufacturing a semiconductor device according to claim 1, wherein the third step is performed after the second step. 3. The method according to claim 1, further comprising a fourth step of performing the second step after the third step, and cleaning the semiconductor substrate with sulfuric acid after the second step. 1
A method of manufacturing a semiconductor device according to item 1. 4. The concentration of hydrofluoric acid in the dilute hydrofluoric acid water is 0.05 to
The method of manufacturing a semiconductor device according to claim 1, wherein the range is 0.3%. 5. A fifth step of performing plasma ashing using a gas containing CF ₄ and O ₂ after the first step, and a plasma ashing using O ₂ gas after the fifth step. The method for manufacturing a semiconductor device according to claim 1, further comprising a sixth step to be performed.