JPH05234880A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To provide a method for completely removing a resist film in the method for removing the film after ion implanting. CONSTITUTION:The method for manufacturing a semiconductor device comprises the steps of ion implanting a substrate with a resist film 2 covering a semiconductor substrate 1 as a mask, then ashing to remove part of the film 2 in a thickness direction in a plasma of gas containing oxygen and carbon tetrafluoride, then dipping the substrate in mixture solution of sulfuric acid and hydrogen peroxide water to remove residual organic matter adhered to the surface of the film 2, then dipping the substrate in hydrofluoric acid to remove a modified layer formed on the surface of the film 2, and then dipping the substrate in mixed solution of sulfuric acid and hydrogen peroxide water to remove the residual film 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for removing a resist film after ion implantation.

In the process of manufacturing a semiconductor device, when a resist film is removed after high-dose ion implantation using the resist film as an implantation mask, an ordinary ashing process forms a deteriorated film on the surface of the resist film and completely removes it. There were cases where it could not be removed.

The present invention can be used as a method for completely removing such an altered film.

[0004]

2. Description of the Related Art A conventional method for removing a resist film uses an ashing apparatus, in which a substrate is placed in oxygen (O ₂ ) plasma and overashing is performed until the resist film is removed.

Then, the wafer is immersed in diluted hydrofluoric acid (HF) to remove the glassy alteration layer formed on the wafer surface. Then, it was immersed in a mixture of sulfuric acid (H ₂ SO ₄ ) and hydrogen peroxide solution (H ₂ O ₂ ) kept at high temperature to dissolve and remove the residue of organic matter contained in the resist.

[0006]

However, according to the conventional method, when attempting to remove the resist film after ion implantation, the resist film is completely overashed.
An altered layer is partially formed on the resist film surface,
After the ashing process was completed, the altered layer was formed directly on the wafer.

[0007] As a result, initially it will remain the altered layer on the surface because can not organics removal is the main component of the altered layer remaining on the surface with hydrofluoric acid treatment performed, followed by performing H ₂
Even if the organic matter is removed by the SO ₄ / H ₂ O ₂ mixed solution treatment, the altered layer cannot be completely removed, so there is a high possibility that it will remain on the surface along with the glassy altered layer formed on the wafer surface. .

Here, the altered layer is considered to be generated as follows. Since the high dose has a longer ion implantation time per area than the low dose, the ion beam is also irradiated onto the resist for a long time, and the upper layer of the resist is hardened by heat (carbon as the main component of the resist). Thermal reaction with implanted ions), but details of the reaction are unknown.

An object of the present invention is to provide a method of completely removing a resist film after ion implantation.

[0010]

[Means for Solving the Problems] To solve the above-mentioned problems, a step of ion-implanting the substrate using a resist film (2) deposited on a semiconductor substrate (1) as a mask, and then containing oxygen A step of ashing and removing a part of the resist film (2) in the thickness direction in a plasma of gas, and then immersing the substrate in a mixed solution of sulfuric acid and hydrogen peroxide solution to form a surface of the resist film (2). The step of removing the residual organic substances attached to the substrate, the step of subsequently immersing the substrate in hydrofluoric acid to remove the deteriorated layer formed on the surface of the resist film (2), and then the substrate being treated with sulfuric acid. The remaining resist film after immersion in a mixture of hydrogen oxide water
(2) is removed by a method of manufacturing a semiconductor device.

[0011]

According to the present invention, the resist film having the altered layer formed on the surface is stopped by half ashing so that the resist film is partially left in the thickness direction. First, the organic matter of the above is removed by a mixed solution of H ₂ SO ₄ / H ₂ O ₂ to expose the deteriorated layer, and then the deteriorated layer on the resist film is removed by hydrofluoric acid treatment, and then the remaining resist film is removed by H 2 It is designed to be removed by a wet process using a mixed solution of ₂ SO ₄ / H ₂ O ₂ .

As a result, since the deteriorated layer is removed on the remaining resist film, it is not directly attached to the substrate surface. After that, the remaining resist film to which the altered layer is not attached may be removed by a wet process.

[0013]

1 (A) to 1 (F) are sectional views for explaining an embodiment of the present invention. In FIG. 1 (A), a resist film 2 having a thickness of 1 μm is deposited on a semiconductor substrate 1 and a region not implanted is left by patterning.

In FIG. 1B, arsenic ions are formed on the substrate.
Inject (As ⁺ ). As ⁺ implantation conditions are energy 70
KeV, dose is 4 × 10 ¹⁵ cm ^-2 . At this time, the altered layer 3 is formed on the surface of the resist film 2 by the high concentration implantation.

In FIG. 1C, the substrate 1 is put into an ashing device, and the resist film 2 is half-ashed under the following conditions. Reactive gas: O ₂ 900 SCCM Gas pressure: 800 mTorr RF Power: 1040 W On the surface of the resist film 2 remaining after half ashing,
Residual deteriorated layer 3 and residual organic matter 4 remain.

In FIG. 1 (D), the substrate is immersed in a mixed solution of H ₂ SO ₄ (94%) / H ₂ O ₂ (10%) = 4: 1 kept at a high temperature of 100 to 110 ° C. to form a resist film. The residual organic matter 4 attached to the surface of 2 is removed to expose the altered layer 3.

In FIG. 1E, hydrofluoric acid treatment is performed to remove the altered layer 3. In Fig. 1 (F), the ratio of H ₂ SO
_{The 4} / H ₂ O ₂ mixture is subjected to high temperature treatment to remove the remaining resist film 2.

In the embodiment, As⁺Dose amount of 4 × 10¹⁵cm^-2of
The case was explained, but 1 × 10¹⁴cm^-2Higher dose
The present invention has an effect on the amount. In addition, the injected ions⁴⁹B
F₂ ⁺ _, ³¹P⁺In the case of etc., the same effect is obtained.

[0019]

The resist film after the ion implantation could be completely removed. As a side effect, the processing time of the ashing device is shortened and the throughput is improved.

[Brief description of drawings]

FIG. 1 is a sectional view illustrating an embodiment of the present invention.

[Explanation of symbols]

 1 semiconductor substrate 2 resist film 3 altered layer 4 residual organic matter

Claims (1)

[Claims] 1. A step of implanting ions into a substrate using a resist film (2) deposited on a semiconductor substrate (1) as a mask, and then the resist film (2) in a plasma of a gas containing oxygen.
A step of ashing and removing a part in the thickness direction of the substrate, and then a step of immersing the substrate in a mixed solution of sulfuric acid and hydrogen peroxide solution to remove residual organic matter adhering to the surface of the resist film (2), Then, the substrate is immersed in hydrofluoric acid to form the resist film.
The method is characterized by including the step of removing the deteriorated layer formed on the surface of (2) and the step of removing the remaining resist film (2) by immersing the substrate in a mixed solution of sulfuric acid and hydrogen peroxide solution. And a method for manufacturing a semiconductor device.