JPH11214290A - Resist film and method of manufacturing semiconductor device - Google Patents

Abstract

(57) Abstract: Provided are a resist film and a method of manufacturing a semiconductor device, in which the influence of charge-up of the resist film during etching is avoided. SOLUTION: An insulating film (BPSG) as a material to be etched is provided.
A resist material 16 is formed on the surface of the film (film) 12, and the entire peripheral surface of the resist material 16 is covered with a conductive film (the amorphous carbon film 1).
After being formed so as to be covered with 4 and 18, the insulating film 12 is etched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a resist film serving as an etching mask used in a semiconductor manufacturing process and a method for manufacturing a semiconductor device. More particularly, the present invention relates to a resist film used for etching by a charged particle beam and the resist film. The present invention relates to a method for manufacturing a used semiconductor device.

[0002]

2. Description of the Related Art As a conventional resist film of this kind, there is a technique described in Japanese Patent Application Laid-Open No. 7-74076. This is a double structure comprising a resist film formed of a resin film sensitive to charged particles, and a conductive film positioned below the resin film and capable of releasing charged particles when the charged particles are irradiated on the resin film. By doing so, it is intended to suppress the charge-up of the resist film during etching, reduce the bending irradiation phenomenon of the charged particle beam, and realize accurate pattern exposure.

[0003]

In the above-mentioned conventional resist film, a conductive film such as a carbon film is formed only under the resist, so that only charges in a portion directly in contact with the conductive film are released. Therefore, there is a problem that it is actually difficult to suppress the charge-up of the resist film.

The present invention has been made in view of such circumstances, and provides a resist film and a method of manufacturing a semiconductor device which avoid the influence of charging up the resist film during etching by a charged particle beam. With the goal.

[0005]

According to a first aspect of the present invention, there is provided a resist material having an entire peripheral surface covered with a conductive film on a surface of a material to be etched. I do.

According to a second aspect of the present invention, a resist material whose surface is covered with a conductive film is formed on the surface of the conductive material to be etched.

According to a third aspect of the present invention, in the resist film according to the first aspect, the material to be etched is an insulating film or a conductive film.

According to a fourth aspect of the present invention, in the resist film according to any one of the first to third aspects, the conductive film covering the material to be etched is an amorphous carbon film.

According to the first, third and fourth aspects of the present invention,
A resist material whose entire surface is covered with a conductive film is formed on the surface of the material to be etched. Can be prevented from being bent by the Coulomb force due to the electric charge accumulated in the substrate. In this case, the material to be etched is, for example, an insulating film, and the conductive film covering the resist material is, for example, an amorphous carbon film. The material to be etched may be a conductive film.

According to the second and fourth aspects of the present invention, since the resist material whose surface is covered with the conductive film is formed on the surface of the conductive material to be etched, the resist material is etched during the etching by the charged particle beam. Is charged up, it is electrostatically shielded, and the charged particle beam can be prevented from being bent by the Coulomb force due to the electric charge accumulated in the resist. In this case, the material to be etched is, for example, a conductive film, and the conductive film covering the resist material is, for example, an amorphous carbon film.

The invention according to claim 5 is characterized in that the etching of the insulating film is performed after forming a resist material whose entire peripheral surface is covered with a conductive film on the surface of the insulating film to be etched. I do.

According to the fifth aspect of the present invention, even if the resist material for forming the resist pattern serving as a mask is charged up during the etching by the charged particle beam, the electric charge accumulated in the resist material remains on the peripheral surface of the resist material. Since the electrostatic shielding is performed by the conductive film, the charged particle beam is prevented from being bent by the Coulomb force due to the charge. As a result, an ideal vertical plane shape can be obtained as an etched surface of the insulating film to be etched.

According to a sixth aspect of the present invention, there is provided a method for etching a conductive material to be etched after forming a resist material having a surface coated with a conductive film on the surface of the conductive material to be etched. Features.

According to the sixth aspect of the invention, even if the resist material for forming the resist pattern serving as a mask is charged up during etching by the charged particle beam, the electric charge accumulated in the resist material remains on the peripheral surface of the resist material. Since the electrostatic charge is shielded by the conductive film to be coated and the conductive material to be etched, the charged particle beam is prevented from being bent by the Coulomb force due to the electric charge. As a result, an ideal vertical plane shape can be obtained as an etched surface of the conductive film as the material to be etched.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a part of the manufacturing process of the semiconductor device according to the first embodiment of the present invention.
In this example, a description will be given of a contact hole etching step which is one of etching of an insulating film. In FIG. 1, a BPS which is a film to be etched is formed on a silicon substrate 10.
G (Boro-Phospho-Silicate G)
thin film 12 is formed by CVD (Chemical Vap).
or Deposition method (FIG. 1).
(A)).

Next, an amorphous carbon film 14 as a conductive film having a thickness of about 2 is formed on the BPSG film 12 by a normal temperature sputtering method.
It is formed to about 00 ° (FIG. 1B). Here, since the amorphous carbon film 14 becomes a hindrance factor at the time of etching, it is desirable to be as thin as possible. Next, a contact hole pattern is formed using a resist 16 by a known lithography method (FIG. 1C). At this time, the dimension of the diameter of the hole 17 of the contact hole pattern formed by the resist 16 is expected to be reduced by the sputtering of amorphous carbon in the next step. For example, the amorphous carbon film is formed by sputtering in the next step. 200 mm thick
It is necessary to make the thickness larger than the set value by about 0.04 μm.

Further, an amorphous carbon film 18 having a thickness of about 200 ° is formed on the entire surface of the silicon substrate 10 patterned by the resist by a normal temperature sputtering method in the same manner as in the step shown in FIG. It is desirable that the film thickness of the amorphous carbon film 18 be as thin as the amorphous carbon film 14. However, if the amorphous carbon film formed on the side wall of the resist 16 is etched away and disappears, the resist 16 Since the effect of electrostatically shielding the charged up charge is lost, about 200 ° is desirable.

By forming the amorphous carbon film 18 in this way, the amorphous carbon film 14 and the amorphous carbon film 18 are connected so as to cover the resist 16, and the amorphous carbon film 14 and the amorphous carbon film 18 have the same potential. (FIG. 1D).

Next, the BPSG film 12 is etched by reactive ion etching (RIE). At this time, the amorphous carbon films 14 and 18 formed on the BPSG film 12 and having a thickness of about 400.degree. Must be removed by reactive etching. Normal etching conditions for forming a contact hole in the insulating film (for example, pressure: 350 mTorr, RF Power: 800 W,
Reaction gas Ar / CHF ₃ / CF ₄ : 200/35/35
sccm), it is possible to etch the amorphous carbon film. However, if the etch rate (selectivity) of the amorphous carbon film with respect to the BPSG film 12 is increased, the BPSG film 12 can be more uniformly etched. Of the fluorine (F) -based gas (CF ₄ / (CF ₄ + CHF ₃ )), for example, from 0 to 30
It is better to increase about%.

In the present embodiment, the flow rate of the reactant gas for etching the amorphous carbon films 14 and 18 is Ar / CH.
It is used as F ₃ / CF ₄ = 200/10/60 sccm (the ratio of CF ₄ is about 15%). Under these conditions, the amorphous carbon films 14 and 18 at the bottom of the contact hole 17 can be removed in about 20 seconds. Thereafter, anisotropic etching is performed under the above-described ordinary etching condition for forming a contact hole in the insulating film.

As a result, the amorphous carbon film 18 formed on the resist 16 is removed, but the amorphous carbon film 18 ′ remains on the side surface of the resist 16 in the form of a sidewall, and is formed below the resist 16. Since the amorphous carbon film 14 remains connected to the amorphous carbon film 14, the amorphous carbon film 18 ′
Is maintained at the same potential as that of the amorphous carbon film 14 (FIG. 1E). Next, a resist 16 and a resist 16
Amorphous carbon film 1 formed on lower layer and side surface
4,18 'and to remove performs ashing by O ₂ plasma, the H ₂ O ₂ was added to further acid (H ₂ SO _4,
(Heated to 120 ° C.). As a result, the resist 16 and the amorphous carbon films 14 and 18 'formed on the lower layer and the side surfaces of the resist 16 are completely removed (FIG. 1F).

According to the first embodiment of the present invention, FIG.
As shown in (1), after the entire peripheral surface of the resist 16 formed on the surface of the BPSG film 12 which is the material to be etched is covered with the amorphous carbon films 14 and 18 'which are the conductive films, the etching of the BPSG film 12 is performed. As a result, the resist 16 is etched during the etching of the BPSG film 12.
Is charged, the charge is electrostatically shielded, so that the charged particle beam 20 to be etched is
As shown in FIG. 4, bending is prevented by Coulomb force due to the electric charge accumulated in 6. As a result, an ideal vertical surface shape is obtained on the etched side surface of the insulating film.

By changing the film thickness T of the amorphous carbon film 18 'formed on the surface of the resist material, it is possible to form a contact hole having a diameter smaller than the critical dimension S of the resolution of photolithography. The dimension adjustment of the diameter D (D = S-2T) of the contact hole is also possible.

Next, a part of the manufacturing process of the semiconductor device according to the second embodiment of the present invention is shown. In this example, an etching process of a polysilicon film will be described as an example of etching a conductive film. In FIG. 2, silicon oxide (Si) as an insulating film is formed on a silicon substrate 10 by thermal oxidation.
After forming an O ₂ ) film, LPCVD (Low Pres)
sure Chemical Vapor Depos
A polysilicon film 22, which is a conductive film serving as a material to be etched, is formed to a predetermined thickness by an ition method (FIG. 2).
(A)). This polysilicon film 22 corresponds to a first conductive film of the present invention.

Next, a resist 16 serving as a mask for patterning the polysilicon film 22 is formed on the entire surface of the polysilicon film 22, and patterned by a usual photolithography method (FIG. 2B). Next, an amorphous carbon film 24 is formed as a conductive film to a thickness of about 200 ° on the exposed surfaces of the polysilicon film 22 and the patterned resist 16 by a normal temperature sputtering method (FIG. 2).
(C)). This amorphous carbon film 24 corresponds to the second conductive film of the present invention.

Further, the polysilicon film 22 is etched by reactive ion etching (RIE). At this time, the amorphous carbon film 24 having a thickness of about 200 ° formed on the polysilicon film 22 is first anisotropically etched. Must be removed by etching. Polysilicon film 2
The higher the etch rate (selectivity) of the amorphous carbon film 24 with respect to 2, the more uniform the etching of the polysilicon film 22, the more the reactive gas used for reactive ion etching of the amorphous carbon film 24 is About 5 O ₂ in CHF ₃ gas or C ₂ F ₆ gas
% Is desirably added.

In the present embodiment, the flow rate of the reaction gas is used for etching the amorphous carbon film 24 with CHF ₃ (or C ₂ F ₆ ) / O ₂ = 100/5 sccm.
Using this condition, the resist 16 and the amorphous carbon film 24 on the polysilicon film 22 can be removed in about 30 seconds. Then, unnecessary portions of the polysilicon film 22 are removed by performing anisotropic etching using the resist 16 as a mask. As a result, the amorphous carbon film 24 formed on the resist 16 is removed, but the amorphous carbon film 24 ′ remains on the side surface of the resist 16 in a side wall shape. Polysilicon film 22 formed in
Is kept connected, the potential of the amorphous carbon film 24 'is maintained at the same potential as the polysilicon film 22 (FIG. 2D). Next, resist 16
In order to remove the amorphous carbon film 24 ′ formed on the side surface of the resist 16, ashing treatment is performed by O ₂ plasma, and H ₂ O ₂ is added to an acid (H ₂ SO ₄ ,
(Heat to 0 ° C.). As a result, the resist 16
And the amorphous carbon film 24 'formed on the side surface of the resist 16 is completely removed (FIG. 2E).

According to the second embodiment of the present invention, a resist 16 is formed on a surface of a polysilicon film 22 which is a material to be etched, and at least an exposed surface of the resist 16 is an amorphous carbon film 24 serving as a conductive film. Since the polysilicon film 22 is etched after being formed so as to be covered with the polysilicon film 22, even if the resist 16 is charged up during the etching of the polysilicon film 22, the charge is transferred to the amorphous carbon film 24 ′ and the polysilicon film 22.
This prevents the charged particle beam to be etched from being bent by the Coulomb force due to the charges accumulated in the resist 16. As a result, the etched side surface of the polysilicon film 22 has an ideal vertical plane shape.

[0029]

As described above, claims 1, 3, and 4
According to the invention described in (1), since the resist material whose entire peripheral surface is covered with the conductive film is formed on the surface of the material to be etched, even if the resist material is charged up during etching by the charged particle beam, the electrostatic shield is formed. As a result, it is possible to prevent the charged particle beam from being bent by the Coulomb force due to the charges accumulated in the resist.

According to the second and fourth aspects of the present invention, since the resist material whose surface is covered with the conductive film is formed on the surface of the conductive material to be etched, the resist material is etched during the charged particle beam etching. Is charged up, it is electrostatically shielded, and the charged particle beam can be prevented from being bent by the Coulomb force due to the electric charge accumulated in the resist.

According to the fifth aspect of the present invention, even if the resist material for forming the resist pattern serving as a mask is charged up during the etching by the charged particle beam, the electric charge accumulated in the resist material remains on the peripheral surface of the resist material. Since the electrostatic shielding is performed by the conductive film, the charged particle beam is prevented from being bent by the Coulomb force due to the charge. As a result, an ideal vertical plane shape can be obtained as an etched surface of the insulating film to be etched.

According to the sixth aspect of the present invention, even if the resist material for forming the resist pattern serving as a mask is charged up during etching by the charged particle beam, the electric charge accumulated in the resist material remains on the peripheral surface of the resist material. Since the electrostatic charge is shielded by the conductive film to be coated and the conductive material to be etched, the charged particle beam is prevented from being bent by the Coulomb force due to the electric charge. As a result, an ideal vertical plane shape can be obtained as an etched surface of the conductive film as the material to be etched.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a manufacturing process of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is an explanatory view showing an example of a manufacturing process of a semiconductor device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram for explaining an effect of the method for manufacturing a semiconductor device according to the first embodiment of the present invention;

FIG. 4 is an explanatory diagram for describing an effect of the method of manufacturing the semiconductor device according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining an effect of the method for manufacturing a semiconductor device according to the first embodiment of the present invention;

[Explanation of symbols]

 Reference Signs List 10 silicon substrate 12 BPSG film 14, 18, 24 amorphous carbon film 16 resist 20 silicon oxide film 22 polysilicon film

Claims (6)

[Claims] 1. A resist film, wherein a resist material whose entire peripheral surface is covered with a conductive film is formed on the surface of a material to be etched. 2. A resist film, wherein a resist material whose surface is covered with a conductive film is formed on the surface of a conductive material to be etched. 3. The resist film according to claim 1, wherein the material to be etched is an insulating film or a conductive film. 4. The resist film according to claim 1, wherein the conductive film covering the material to be etched is an amorphous carbon film. 5. A method for manufacturing a semiconductor device, comprising: forming a resist material whose entire peripheral surface is covered with a conductive film on the surface of an insulating film to be etched; and etching the insulating film. 6. A method for manufacturing a semiconductor device, comprising: forming a resist material whose surface is covered with a conductive film on a surface of a conductive material to be etched; and etching the conductive material to be etched. .