JPH06252043A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method that removes resists after ions are implanted with high accuracy and ease. CONSTITUTION:This invention relates to a pattern formation method which includes a step of forming a resist 2 on a wafer 1, a step of forming a resist pattern 2A by the exposure and the development with a required mask 3, a step of implanting ions 5 into the wafer using the resist pattern 2A as a mask, a step of implanting acid ions at a dosage lower than that of the ion implantation and a step of removing the resist pattern 2A with an acid solution.

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.

[0002]

2. Description of the Related Art In semiconductor manufacturing, resist removal after ion implantation, particularly ion implantation at high dose, is impossible by ordinary acid cleaning, and is therefore performed by dry ashing using O ₂ . . However, there is a problem that the resist cannot be completely removed even by this method.

An example of the conventional pattern forming method described above will be described below with reference to the drawings. 3A to 3C are process sectional views of a conventional pattern forming method.

In FIG. 3A, a resist (TSMR-V3 manufactured by Tokyo Ohka Kabushiki Kaisha) 2 made of novolac resin and naphthoquinone diazide 2 is formed on the substrate 1 to a thickness of 1.5 μm.
Exposure 4 is performed with an i-line stepper (NA 0.50) through the desired mask 3 for ion implantation (FIG. 3 (b)). After that, in FIG. 3 (c), positive exposure is performed by post-exposure heating and development. The pattern 2A of the mold was formed. Next high dose (5X1
0 ¹⁶ ) As ⁺ 5 was injected into the substrate using the pattern 2A as a mask. This Couto 3 (d), has been attempted to remove the pattern 2A, in order to resist surface-degraded by the ion implantation, it can not be completely removed by the usual mixed solution of sulfuric acid and hydrogen peroxide, instead O ₂ Dry ashing 9 was performed. Although the resist pattern 2A was almost removed by ashing, the resist pattern 2A was not perfect, and residues and particles 10 were observed on the substrate 1 (FIG. 3).
(E)).

[0005]

Such residues and particles cause defects in the post-process and cause a decrease in device yield. It is also possible to further perform acid cleaning in order to remove such residues and particles, but the throughput already deteriorated in the dry ashing process will be further deteriorated and the process cost will also be very bad. Therefore, it was difficult to adopt it industrially.

In view of the above problems, the present invention provides a method for removing a resist after ion implantation with high accuracy and in a simple manner.

[0007]

SUMMARY OF THE INVENTION In order to solve the above problems, according to the present invention, after the desired ion implantation, oxygen or hydrogen ions having a dose lower than the ion implantation dose are implanted to improve performance and productivity. The feature is that the resist pattern is completely removed only with an acidic solution without using dry ashing, which has a bad effect.

That is, according to the present invention, a step of forming a resist on a substrate, a step of exposing using a desired mask and forming a resist pattern by development, and ion implantation into the substrate using the resist pattern as a mask. A pattern forming method comprising: a step, a step of implanting oxygen or hydrogen ions having a dose lower than the dose of the ion implantation, and a step of removing the resist pattern with an acidic solution.

[0009]

[Function] Usually, by performing high-dose ion implantation, the surface of the resist is modified into a film containing many carbon atoms.
It is difficult to oxidize in an acidic solution. According to the method of the present invention, the carbon-carbon bond in a film can be weakened by allowing an oxygen atom or a hydrogen atom to enter a film having many carbon atoms. As a result, the film can be easily oxidized and removed only with the acidic solution. The method of the present invention is an effective method by controlling the dose amount of oxygen or hydrogen ion implantation regardless of the surface-hardened film thickness of the resist film. The dose of oxygen or hydrogen ion implantation is arbitrary, but in order to avoid the adverse effect of the hardening effect on the film surface due to these ions, it is usually lower than the high dose ion implantation initially performed. Is desirable. Also, these oxygen or hydrogen ions do not adversely affect the characteristics of the device even if they are implanted into the substrate.

[0010]

【Example】

(Embodiment 1) Hereinafter, a pattern forming method according to an embodiment of the present invention will be described with reference to FIG.

In FIG. 1A, a resist (TSMR-V3 made by Tokyo Ohka Kabushiki Kaisha) 2 made of novolac resin and naphthoquinone diazide 2 is formed on the substrate 1 to a thickness of 1.5 μm.
In FIG. 1B, an exposure 4 is performed with an i-line stepper (NA 0.50) through a desired mask 3 for ion implantation, and thereafter, a positive pattern 2A is formed by heating after exposure and development.
Was formed (FIG. 1 (c)). Next high dose (5X1
0 ¹⁶ ) As ⁺ 5 was injected into the substrate using the pattern 2A as a mask.

Thereafter, in FIG. 1D, 4 × 10 ¹² of oxygen 6 was injected to modify the film surface so that it was easily oxidized. Thereafter, in FIG. 1E, at 130 ° C., sulfuric acid: hydrogen peroxide solution = 5:
When the washing was performed with the acidic solution of No. 1 for 10 minutes, the resist pattern 2A could be completely removed without any residue or particles.

(Embodiment 2) A pattern forming method according to an embodiment of the present invention will be described below with reference to FIG.

In FIG. 2A, a DUV resist 7 containing a compound which generates an acid by an energy ray having a composition of (Table 1) and a resin which becomes alkali-soluble when the protecting group is eliminated by the acid is formed on the substrate 1 in FIG. 2A. Form to a thickness of 1.5 microns.

[0015]

[Table 1]

In FIG. 2B, the desired mass for ion implantation is
KrF excimer laser stepper (NA0.
42), exposure 4 ′ is performed, and then post-exposure heating and development are performed.
To form a positive pattern 7A (see FIG. 2).
(C)). Next high dose (5X10 ¹⁶) As⁺5
The substrate was injected using the turn 7A as a mask.

After that, in FIG. 2D, 5 × 10 ¹³ hydrogen 8 was injected to modify the film surface so that it was easily oxidized. After that, in FIG. 2E, at 130 ° C., sulfuric acid: hydrogen peroxide solution = 5:
When cleaning was performed with the acidic solution of No. 1 for 10 minutes, the resist pattern 7A could be completely removed without any residue or particles.

The acidic solution used in the present invention may be, but is not limited to, sulfuric acid, hydrogen peroxide solution, nitric acid, or a mixed solution thereof. As the resist used in the present invention, a resist consisting of a novolak resin and naphthoquinonediazide, a resist consisting of a resin that becomes alkali-soluble by elimination of a protective group by an acid and a compound that generates an acid by energy rays, such as any organic, An inorganic resist can be used.

[0019]

As described above, according to the present invention, the resist removal after ion implantation, which has been difficult by the conventional method, can be simply and completely performed. Since it also has the merit of significantly reducing throughput and process cost, it can be said to be a method of manufacturing a semiconductor device having extremely high industrial value with improved element productivity and yield.

[Brief description of drawings]

FIG. 1 is a process sectional view of a pattern forming method according to a first embodiment of the present invention.

FIG. 2 is a process sectional view of a pattern forming method according to a second embodiment of the present invention.

FIG. 3 is a process sectional view of a conventional pattern forming method.

[Explanation of symbols]

1 substrate 2 resist 3 mask 4 i-ray light 4'KrF excimer laser light 5 As ⁺ 6 O ⁺ 7 DUV resist 8 H ⁺ 2A, 7A pattern

Claims (1)

[Claims] 1. A step of forming a resist on a substrate, a step of exposing using a desired mask and forming a resist pattern by development, a step of implanting ions into the substrate using the resist pattern as a mask, A pattern forming method comprising: a step of implanting oxygen or hydrogen ions having a dose lower than the dose of ion implantation; and a step of removing the resist pattern with an acidic solution.