JPH05251323A - Pattern formation - Google Patents

Abstract

PURPOSE:To provide a pattern formation method wherein the limit of the fineness of a pattern can be enhanced further in a silylating image reversal process regarding the pattern formation method by a two-layer silylating image reversal process by a method wherein, after an upper-layer photosensitive resin film has been patterned by a selective exposure operation and a development operation, a lower-layer resin film is silylated and removed selectively. CONSTITUTION:The title formation method is constituted by including the following: a process wherein a photosensitive resin film 14 on a resin film 13 on a body 12 to be patterned is patterned by a selective exposure operation and a development operation; a process wherein the surface of the resin film 13 is irradiated with a beam of light at a prescribed angle in a range which is larger than 0 deg. and smaller than 90 deg. by making use of a patterned photosensitive resin film 14a as a mask and a silylated layer 15 which contains silicon is formed on the surface layer of the resin film 13; and a process wherein a mask pattern film by the resin film 13 is formed by making use of the silylated layer 15 as a mask and a pattern composed of the body 12 to be patterned is formed by making use of the mask pattern film as a mask.

Description

Detailed Description of the Invention

(Table of Contents) -Industrial application field-Conventional technology (Figs. 4 and 5) -Problems to be solved by the invention-Means for solving the problem-Action-Examples (Figs. 1 to 3) ) ·The invention's effect

[0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and more specifically, after patterning an upper photosensitive resin film by selective exposure and development, the lower resin film is selectively silylated and removed. The present invention relates to a pattern forming method by a two-layer silylated image reversal process.

[0003]

2. Description of the Related Art A conventional pattern formation method by a two-layer silylation image reversal process is shown in FIG.
Description will be made with reference to (c), FIG. 5 (d), and (e).

First, as shown in FIG. 4A, the first resist film 3 is formed on the object to be patterned 2 on the semiconductor substrate 1.
Then, the second resist film 4 is formed. The first lower layer
The resist film 3 used in (1) has a higher silylation reaction rate than the upper second resist film 4.

Then, the upper second resist film 4 is selectively exposed by using ultraviolet rays or electron beams and developed to form a first resist pattern film 4a consisting of the upper second resist film 4 ( FIG. 4B).

Next, while exposing the first resist film 3 to the organic silane liquid or the organic silane gas, light is vertically irradiated from above the first resist pattern film 4a onto the surface of the first resist film 3. As a result, the first resist pattern film 4a serves as a mask, and the surface of the first resist film 3 under the region other than the region immediately below the region where the first resist pattern film 4a is formed is silylated and silylated. Layer 5 is formed (FIG. 4 (c)).

Next, using the silylated layer 5 as a mask, the first resist pattern film 4a and the first resist film 3 are formed.
Are selectively removed by dry etching to form a second resist pattern film 3a having openings 6 formed in the first resist film 3 (FIG. 5D). As a result, the upper first resist pattern film 4a becomes the first resist film 3
Is transcribed to. The pattern image of the second resist pattern film 3a is the upper first resist pattern film 4
Since it is the reverse of the pattern image of a, it is called image reversal.

After that, when the patterned body 2 is selectively removed by etching using the second resist pattern film 3a as a mask, the opening 7 is formed and the pattern formation is completed (FIG. 5 (e)). Thereby, for example, a contact hole is formed on the S / D region layer (not shown).

[0009]

By the way, in the above-mentioned pattern forming method, there is a limit to the miniaturization of the pattern because of the limitation due to the resolution limit of the upper second resist film 4. Further, the dimension shift of the first resist pattern film 4a due to the dry etching is added, so that the restriction on the miniaturization of the pattern is further increased. Therefore, there is a problem that it is difficult to make the pattern fine.

The present invention was created in view of the problems of the prior art, and provides a pattern forming method capable of further improving the limit of pattern miniaturization in a silylated image reversal process. To aim.

[0011]

The above-mentioned problems are, firstly, a step of forming a resin film and a photosensitive resin film on an object to be etched in order and then patterning the photosensitive resin film by selective exposure and development. And exposing the surface of the resin film to a reaction liquid or a reaction gas containing silicon using the patterned photosensitive resin film as a mask, in a range of more than 0 degrees and less than 90 degrees with respect to the surface of the resin film. The step of irradiating light at a predetermined angle to form a silylated layer containing silicon on the surface layer of the resin film to which the light of the predetermined intensity has reached, and selecting the resin film by etching using the silylated layer as a mask Of the resin film to form a mask pattern film, and the mask pattern film is used as a mask to selectively etch the object to be etched, It is achieved by the pattern forming method and a step of forming a pattern of grayed body, second
In the third aspect, the light used for forming the silylated layer is light having a uniform wavelength. Thirdly, the light used for forming the silylated layer is achieved by the pattern forming method according to claim 1. Is achieved by the pattern forming method according to the first or second invention, characterized in that light having a uniform direction is used. Fourthly, the silylation is performed by using a resin containing a benzene ring as the resin film. The pattern forming method according to the first, second or third invention is characterized in that deep ultraviolet light having a wavelength of 240 nm or less is used as the light used for forming the layer.

[0012]

[Operation] According to the pattern forming method of the present invention, when the silylated layer is formed, light is applied to the lower resin film at a predetermined angle larger than 0 ° and smaller than 90 ° with respect to the surface of the resin film. Since the irradiation is performed, light is obliquely transmitted to the resin film below the remaining region of the patterned upper photosensitive resin film, and the resin film in this portion is also silylated. At this time, depending on the incident angle of light, the width of the light transmissive region in the resin film that enters the inside lateral direction with respect to the side wall of the patterned upper photosensitive resin film as a reference changes. By controlling, the width of the silylated layer can be controlled. As a result, it becomes possible to control the pattern width of the mask pattern film formed of the lower resin film formed by etching using the silylated layer as a mask.

Further, as the light used for forming the silylated layer, since at least one of light having a uniform wavelength and light having a uniform direction is used, the light transmission distance to the lower resin film, that is, The lateral penetration width of the silylated layer formed on the resin film can be controlled with good reproducibility.

Further, since far ultraviolet rays having a wavelength (λ) of 240 nm or less are used as the light used for forming the silylated layer, the well-known light transmittance calculated by the inventor of the present invention is shown in FIG. As shown in (1), the resin film can be formed within a practical thickness range by making the light transmission distance in the resin film relatively short. In addition, since a resin film containing a benzene ring (for example, a novolac-based resist film) is used as the lower resin film, it is well known that the resin film has sufficient resistance to the reaction gas for etching the object to be patterned. Can be held.

[0015]

Embodiments of the present invention will now be described with reference to the drawings. A pattern forming method by a two-layer silylated image reversal process according to an embodiment of the present invention will be described with reference to FIGS.

First, as shown in FIG. 1A, a film thickness of about 2 μm is formed on an insulating film (patterned body) 12 made of a silicon oxide film on a semiconductor substrate 11 on which an S / D region layer 18 is formed. Novolak-based first resist film (resin film) 13 having the above and chloromethylstyrene-based second resist film (photosensitive resin film) 1 having a film thickness of about 0.8 μm
4 is formed. The lower first resist film 13 has a higher silylation reaction rate than the upper second resist film 14, and is a reaction gas such as CF ₄ gas used for etching the insulating film 12. It is necessary to use a material having a benzene ring that has good resistance to.

Then, the upper second resist film 14 is selectively exposed using ultraviolet rays or electron beams, and then developed,
A first resist film 14 having an upper layer with a width of about 1 μm
Forming a resist pattern film 14a (FIG. 1 (b)).

Next, the semiconductor substrate 11 is placed in the chamber of the film forming apparatus and placed on the mounting table. Then, while rotating the semiconductor substrate 11 at a rotation speed of 50 RPM, the pressure in the chamber is adjusted to about 400 Torr and exposed to an organic chlorosilane gas as a silylating agent, and the first resist pattern film 14a is exposed from above the first resist pattern film 14a. The surface of the resist film 13 is irradiated with light having a wavelength (λ) of 235 nm in the direction of 45 degrees. At this time, the light source used is 233 to 238 μ.
An Xe-Hg lamp combined with a narrow bandpass filter of m is used to align the directionality of light emitted from the light source within a range of ± 1 degree, and the intensity is set to 60 mw / cm ² . Further, deep ultraviolet (Deep UV) (light) having a uniform wavelength around 235 nm is supplied by a filter. As shown in FIG. 3 showing a well-known transmittance, deep ultraviolet rays enter the first resist film 13 at an angle of about 0.3 μm from a direction of 45 degrees with respect to the surface of the first resist film 13. As a result, the silylating agent that has entered the first resist film 13 by diffusion in advance reacts with the NH groups or COOH groups in the first resist film 13 due to the action of far ultraviolet rays, and the light arrives, and The area irradiated with a predetermined intensity is silylated. Therefore, the lateral intrusion width W of the silylated layer 15 in the first resist film 13 which enters the inner side with reference to the side wall of the patterned second resist film 14a is about 0.2 μm (FIG. 1 (c)).

Then, the first resist pattern film 14a is etched and removed by dry etching using oxygen gas, and the first resist film 13 is continuously selectively removed using the silylated layer 15 as a mask. Then, the second resist pattern film (mask pattern film) 13a having the openings 16 is formed in the first resist film 13. At this time, the peripheral edge portion of the opening 16 of the second resist pattern film 13a has a width of about 1 μm.
The pattern dimension width is about 0.6 μm because it is formed in a region inwardly extending from the end of a by 0.2 μm in the lateral direction. As a result, the upper first resist pattern film 14 is formed.
a is transferred to the first resist film 13 (see FIG. 2).
(D)).

After that, the insulating film is selectively removed by dry etching using CF ₄ gas or the like with the second resist pattern film 13a as a mask, and the S / D of the semiconductor substrate 11 is removed.
A contact hole 17 is formed in the insulating film 12 on the region layer 18. This completes the pattern formation (see FIG. 2).
(E)).

As described above, according to the pattern forming method of the present invention, when the silylated layer is formed, it is separated from the surface of the first resist film 13 by an angle of 45 degrees to the lower first resist film 13. Since ultraviolet rays are radiated, the lateral entry width W of the silylated layer 15 can be controlled by controlling the incident angle of far ultraviolet rays. As a result, the second resist pattern film 13a formed of the lower first resist film 13 finally formed by using the silylated layer 15 as a mask.
It is possible to control the pattern width of.

Further, as the light used for forming the silylated layer 15, since at least one of deep ultraviolet rays having a uniform wavelength and deep ultraviolet rays having a uniform direction is used, the light to the first resist film 13 as the lower layer is used. Transmission distance of the silylated layer 15
It is possible to control the lateral insertion width W of the with good reproducibility.

Further, since far ultraviolet rays having a wavelength (λ) of 240 nm or less are used as the light used for forming the silylated layer 15, the light transmission distance in the first resist film 13 is made relatively short, The first resist film 1 within a practical thickness range
3 can be formed. Further, since a novolac-based resist film containing a benzene ring is used as the lower first resist film 13, sufficient resistance to a reaction gas for etching the insulating film 12 and the like made of a silicon oxide film or the like is secured. be able to.

In the embodiment, the incident angle of far ultraviolet rays used for forming the silylated layer 15 is set to the first resist film 1.
Although it is set to 45 degrees with respect to the surface of No. 3, it can be set to an arbitrary angle of 0 to 90 degrees according to the dimensional width of the second resist pattern film 13a. For example, the smaller the angle of incidence is, the larger the lateral width W of the silylated layer 15 under the first resist pattern film 14a can be made. Can be made smaller.

When irradiating deep ultraviolet rays to form the silylated layer 15, the first resist pattern film 14a is exposed to the first resist pattern near the peripheral portion of the first resist pattern film 14a and in contact with the first resist film 13. Since it is possible that light passes through the first resist film 13 through the resist pattern film 14a-first resist film 13 of FIG.
When it is desired to reduce the light transmission distance to 3 to further improve the pattern accuracy, as long as various conditions allow,
It is desirable that the light transmittance of the second resist film 14 be smaller than that of the first resist film 13.

Further, although the present invention is applied to the formation of the contact holes 17, the formation of via holes on the wiring layer,
It can also be applied to the formation of a wiring layer. Further, although the remaining pattern is formed as the first resist pattern film 14a and the second resist pattern film 13a is used as the blank pattern, the blank pattern is formed as the first resist pattern film and the second resist pattern film is formed. It is also possible to use the remaining pattern.

[0027]

As described above, according to the pattern forming method of the present invention, during the silylation, it is larger than 0 degree with respect to the sidewall of the patterned upper photosensitive resin film,
Since the resin film as the lower layer is irradiated with light at a predetermined angle in the range of less than 10 degrees, the lateral entrance width of the silylated layer can be controlled by controlling the incident angle of light. This makes it possible to control the pattern width of the mask pattern film, which is finally formed of the resin film of the lower layer, using the silylated layer as a mask.

As the light used for forming the silylated layer, at least either light with a uniform wavelength or light with a uniform direction is used. Therefore, the light transmission distance to the lower resin film, that is, the silylation is performed. The layer penetration width can be controlled with good reproducibility.

Further, since far-ultraviolet rays having a wavelength (λ) of 240 nm or less are used as the light used for forming the silylated layer, the light transmission distance in the resin film is made relatively short, and a practical film thickness is obtained. The resin film can be formed within the range. Further, since the lower resin film containing a benzene ring is used, it is possible to sufficiently secure the resistance to the reaction gas for etching the object to be patterned.

[Brief description of drawings]

FIG. 1 is a sectional view (No. 1) for explaining a pattern forming method according to an embodiment of the present invention.

FIG. 2 is a sectional view (No. 2) for explaining the pattern forming method according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram of the transmittance of various resist films used in the examples of the present invention.

FIG. 4 is a sectional view (No. 1) for explaining a conventional pattern forming method.

FIG. 5 is a sectional view (No. 2) for explaining the pattern forming method of the conventional example.

[Explanation of symbols]

11 semiconductor substrate, 12 insulating film (patterned object), 13 first resist film (resin film), 13a second resist pattern film (mask pattern film), 14 second resist film (photosensitive resin film), 14a First resist pattern film, 15 Silylation layer, 16 Opening, 17 Contact hole, 18 S / D region layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location 8831-4M H01L 21/30 341 S

Claims (4)

[Claims] 1. A step of sequentially forming a resin film and a photosensitive resin film on an object to be patterned, and then patterning the photosensitive resin film by selective exposure and development, and a mask of the patterned photosensitive resin film. As the surface of the resin film is exposed to a reaction liquid or reaction gas containing silicon, the surface of the resin film is irradiated with light at a predetermined angle larger than 0 degree and smaller than 90 degrees,
A step of forming a silylated layer containing silicon on the surface layer of the resin film to which light of a predetermined intensity has reached, and selectively removing the resin film by etching using the silylated layer as a mask, And a step of forming a pattern of the patterned object by selectively etching the patterned object using the mask pattern film as a mask. 2. The light having a uniform wavelength is used as the light used for forming the silylated layer.
The described pattern forming method. 3. The light having a uniform direction is used as the light used for forming the silylated layer.
Alternatively, the pattern forming method according to claim 2. 4. A resin containing a benzene ring is used as the resin film, and far ultraviolet rays having a wavelength of 240 nm or less is used as light used for forming the silylated layer. Item 3. The pattern forming method according to Item 3.