JPH06138664A - Pattern forming method - Google Patents

Abstract

PURPOSE:To obtain an antireflection film and inhibiting film for a photoresist when a multilayered wiring pattern is formed by forming a specified silicone ladder polymer film on the lower or upper layer side of the photoresist film. CONSTITUTION:A photoresist film formed on a layer to be patterned such as metal layer is exposed and developed according to a specified pattern to form a resist pattern. Then the resist pattern is used as a mask to selectively remove the layer for patterning. In this process, a silicone ladder polyer film expressed by formula is formed as an antireflection film for exposure or foam inhibiting film for the photoresist on the lower or upper side of the photoresist film. In formula, R<1> is a phenyl group, lower alkyl group, or photosensitive group, R<2> is a hydrogen atom, lower alkyl group, or photosensitive group, and (n) is an integer 20-1000, This silicone ladder polymer film contains a dye or compd. which absorbs light used for photolithography.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and more particularly to an improvement of a pattern forming method suitable for forming a multi-layer wiring in the manufacture of a semiconductor device such as an LSI.

[0002]

2. Description of the Related Art In a semiconductor device such as an LSI of this type, the miniaturization of the element structure and the multi-layer wiring have been remarkably advanced with the high integration.

FIGS. 4 (a) to 4 (e) show a pattern forming method for miniaturizing an element structure and multilayer wiring in a conventional general semiconductor device manufacturing, in which a single layer resist process is used. The main steps of the pattern forming method are sequentially shown.

4 (a) to 4 (e), in the case of the conventional method, first, the metal layer 4 having a predetermined thickness for forming elements is formed on the main surface of the semiconductor substrate 41.
2 is formed ((a) in the figure), and a photoresist film 43 having a required film thickness is formed on the metal layer 42 ((b) in the figure).

Next, the photoresist film 43 is subjected to an exposure process and a development process by an exposure device (not shown) to selectively form a resist pattern 43a (FIG. 3C), and then the selective formation. Using the resist pattern 43a thus formed as an etching mask, the metal layer 42 is
Is selectively processed and removed by, for example, dry etching to leave the patterned metal layer 42a (see FIG.
(d)).

Finally, by removing the resist pattern 43a used as the etching mask, as a result, the metal layer 42a, which is patterned and formed on the main surface of the semiconductor substrate 41 as desired, is formed. That is, in this case, the metal layer 42a as the wiring layer is obtained ((e) in the same figure).

[0007]

However, in the conventional pattern forming method described above, the base substrate side such as the metal layer 42 to be patterned is highly reflective to the light for exposure when forming the multilayer wiring. If you have a rate,
Accurate resist patterns may not always be obtained due to halation in the photoresist film 43.

That is, in the case of a single-layer resist process in the production of a conventional semiconductor device such as an LSI, for example, as described in SOLID STATE TECHNOLOGY, November 1991, p. When the surface of the underlying substrate (or the metal layer) has a high reflectance with respect to the light used for lithography, the incident light from the exposure apparatus and the light reflected from the surface of the underlying substrate (or the metal layer) are This causes the inconvenience of mutual interference in the photoresist film.

The intensity of light due to this interference varies depending on the film thickness distribution of the photoresist and the film thicknesses of the silicon oxide film and the nitride film formed on the surface of the underlying substrate, and the photo intensity is also changed accordingly. It is known that the dose required for exposure of the resist also changes, and this causes local overexposure or underexposure, and the line width of the formed resist pattern also changes. It will be. On the other hand, when a metal layer as wiring is formed on the surface of the base substrate that is not planar, the reflected light hits the resist from the oblique direction to the upper side, and in this case, reflective notching occurs, which causes the final notch. There is a risk that the circuit wiring formed in the device may have a cut or the like, so that a reliability problem such as stress migration is likely to occur in the device configuration.

Therefore, as an antireflection film for solving such a problem, conventionally, an inorganic TiN,
Sputtered films made of Se, Cr ₂ O ₃ , TiW, etc., and CVD films have been studied. In the antireflection film formed of each of these deposition type inorganic films, the reflectance is reduced by utilizing the multiple reflection of light within the inorganic film, and therefore the uniformity of the film thickness is strictly required. However, it is very difficult to form a uniform film thickness here, and on the other hand, it is difficult to remove this inorganic film after resist exposure, and dust is often generated during the removal. There is a disadvantage. Further, in this type of inorganic film containing a metal, so-called metallization occurs when the base side is a metal, so that its applicable range is limited. Further, in the exposure by the stepper, it is necessary to irradiate strong light within a very short time. Therefore, in this case, nitrogen generated due to decomposition of the photosensitizer in the photoresist due to photochemical reaction, etc. For, for example, Microelectric Engineering, 11
(1990), p. 475, there is also the disadvantage of causing photoresist bubbling.

The present invention has been made in order to solve the above-mentioned conventional problems, and an object thereof is to effectively prevent reflection of a photoresist when a multilayer wiring is formed by using a resist process. A film or a photoresist foaming prevention film is easily obtained,
It is to provide a pattern forming method of this kind.

[0012]

In order to achieve the above-mentioned object, a pattern forming method according to the present invention uses a photoresist as an antireflection film or a photoresist foaming prevention film for a photoresist during exposure processing by photolithography. On the lower layer side or upper layer side of the resist film,
A silicone ladder polymer film containing a dye or a compound that absorbs light used in photolithography is formed.

That is, according to the present invention, a photoresist film is formed on a patterned layer such as a metal layer to be patterned, and then the photoresist film is exposed and developed according to a required pattern to form a resist pattern. In the pattern forming method of forming a pattern of the photoresist film using the resist pattern as a mask and selectively removing and patterning the layer to be patterned, the lower layer side or the upper layer side of the photoresist film is exposed. The following formula (2)
The method for forming a pattern is characterized by forming a silicone ladder polymer film represented by.

[0014]

[Chemical 2] (Here, in the above formula, R1 is a phenyl group, a lower alkyl group, or a photosensitive group, which may be the same or different. R2 is a hydrogen atom, a lower alkyl group, or a photosensitive group. And may be the same or different, and n represents an integer of 20 to 1000.)

In the pattern forming method according to the present invention, the silicone ladder polymer film is a spin coating film, and the silicone ladder polymer film is exposed to a g-line or an i-line of a mercury lamp or a laser beam. A dye contained in the silicone ladder polymer film, characterized by containing a dye or a compound that absorbs
Alternatively, the compound has a high purity, especially a heavy metal,
An impurity such as an alkali metal or alkaline earth metal having a concentration of about 0.5 ppm or less, an aromatic compound, a benzoxazole compound, a butadiene cyano compound,
It is characterized by using a polyene compound.

In the pattern forming method of the present invention, when the silicone ladder polymer film is used as an antireflection film, the reflectance from the pattern forming layer side is about 30% or less. When the silicone ladder polymer film is used as an antifoaming film, the reflectance from the patterned layer side is about 10% or less.

Further, according to the present invention, in the pattern forming method, the silicone ladder polymer film is reflected,
When used as an antifoaming film, in order to obtain a reflectance of about 30% or less and about 10% or less from the pattern forming layer side, a dye or compound is added to the silicone ladder polymer film in an amount of 5 to 5%. 20% by weight, and when the silicone ladder polymer film is used as a reflection and antifoaming film,
In order to improve the adhesiveness and adhesion to the patterned layer and the photoresist film, the silane coupling agent is added to the silicone ladder polymer film in an amount of 500 to 500.
It is characterized by containing about 2000 ppm.

Here, the silicone ladder polymer film may be one represented by the chemical formula (2) as described above, and examples thereof include polyphenylsilsesquioxane, polyphenylvinylsilsesquioxane, and polyphenylsilsesquioxane. At least one of phenylmethylsilsesquioxane, polyvinylsilsesquioxane, and polyarylsilsesquioxane is used.

Further, as the dye or compound,
As long as it can absorb at least one kind of light among the g-line (436 nm), i-line (436 nm), and excimer laser (248.5 nm, 251 nm, 193 nm) in a mercury lamp, in this case, g-line For the dyes for polyene compounds, for example, 4-Tricyanovinylaniline, for the i-ray, benzoxazole compounds, or for butadiene cyano compounds, for example, 2- (Styryl) benzoxazole, for the excimer laser, As the dye, aromatic compounds such as 1-4-Benzoquinone are used.

Further, as the silane coupling agent, in this case, for example, Vinyltri-chlorosilan, γGlyc is used.
idoxypropyltrimethoxysilane, n- (Trimethoxysiltlpro
pyl) ethylenediamin or the like is used.

[0021]

Therefore, according to the method of the present invention, a silicone ladder containing a dye or a compound that absorbs light used in photolithography as shown in the chemical formula (2) is provided on the lower layer side or the upper layer side of the photoresist film. Since the polymer film is formed, the reflectance of light from the base substrate side can be reduced, and the effect of light interference in the photoresist film can be reduced to a negligible level, and it is necessary for exposure. Changes in dose can also be ignored. In addition, there is no occurrence of reflective notching during photolithography on a base substrate having a step, and when the photoresist is formed on the upper layer of the photoresist film, the light of the stepper is reduced to expose the photoresist. By making the photochemical reaction in the film mild and prolonging the exposure time, it is possible to prolong the diffusion time of generated nitrogen and prevent foaming.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, different embodiments of the pattern forming method according to the present invention will be described in detail with reference to FIGS.

First embodiment . 1 (a) to 1 (g) are schematic cross-sectional views sequentially showing main manufacturing steps of a pattern forming method to which the first embodiment of the present invention is applied.

In the method of the first embodiment, first, a semiconductor substrate 1 having a required metal layer 2 for forming wiring or elements on the main surface of the substrate is prepared by a conventional technique (see FIG. 1). (a)).

Next, with respect to the main surface of the semiconductor substrate 1 including the metal layer 2, a silicone ladder polymer having a weight average molecular weight of 100,000 as shown in the following formula (3), Anisole solution (adjusted to a concentration of 5% by weight) of a butadiene cyano compound-based dye (containing 20% by weight with respect to a silicone ladder polymer) having absorption near the i-line of a mercury lamp was spin-coated and at 150 ° C. Then, a heat treatment was sequentially performed for 30 minutes at 250 ° C. for 60 minutes at 250 ° C. to form a silicone ladder polymer film 3 having a film thickness of about 0.2 μm (FIG. 2 (b)).

[0026]

[Chemical 3] Here, the silicone ladder polymer having a hydroxyl group at the terminal, which is represented by the above chemical formula (3), is disclosed in JP-A-1-92224.
What was manufactured by the method disclosed in Japanese Patent Laid-Open Publication No. 2004-242242 was used, and the reflectance from the lower ground at this time was 10% or less. According to the experiments conducted by the inventors, the reflectance from the underlying surface is preferably about 30% or less in the case of the antireflection film and about 10% or less in the case of the antifoaming film. In order to obtain the rate, the content of the dye or compound in the silicone ladder polymer is preferably in the range of 5 to 20% by weight.

Next, as in the case of the prior art, a photoresist layer 4 having a required film thickness was formed on the silicone ladder polymer film 3 (FIG. 2 (c)).

Next, as in the case of the prior art, the photoresist layer 4 is exposed by an i-line stepper of a mercury lamp, and also, as in the case of the prior art, a development process is performed, whereby selective etching is performed. A resist pattern 4a was formed on. In the resist pattern 4a thus formed, neither line width variation due to light interference nor reflective notching was observed. Subsequently, using the selectively formed resist pattern 4a as an etching mask, the silicone ladder polymer film 3 is selectively processed and removed by, for example, dry etching to leave the patterned silicone ladder polymer film 3a ( The same figure (d)).

Next, a resist pattern 4 containing the silicone ladder polymer film 3a left by the selective processing.
Using a as an etching mask, the metal layer 2 is selectively processed and removed by, for example, dry etching to form a metal layer 2a having a required pattern shape as desired (FIG. 2 (e)). As in the case of the technique, the resist pattern 4a is removed ((f) in the same figure).

Finally, the silicone ladder polymer film 3a is removed by, for example, wet etching, so that the metal layer 2a on the main surface of the semiconductor substrate 1 is patterned as desired. Is obtained ((g) in the same figure).

Second embodiment . 2 (a) to 2 (f) are schematic cross-sectional views sequentially showing main manufacturing steps of a pattern forming method to which the second embodiment of the present invention is applied. This is the case when there is a step on the side.

Also in the method of the second embodiment, first, as in the case of the method of the first embodiment, the metal layer 12 for forming wiring or elements on the main surface of the substrate and A semiconductor substrate 11 in which an interlayer insulating film 13 covering the metal layer 12 is sequentially formed is prepared ((a) in the same figure).

Next, on the main surface of the semiconductor substrate 11 including the metal layer 12 and the interlayer insulating film 13, a silicone ladder polymer having a weight average molecular weight of 100,000 shown in the above chemical formula (2) is added. While spin-coating an anisole solution (adjusted to a concentration of 5% by weight) of a benzoxazole compound-based dye (containing 20% by weight based on the silicone ladder polymer) having absorption in the vicinity of i-line of a mercury lamp, Heat treatment was sequentially performed at 80 ° C. for 30 minutes and at 125 ° C. for 60 minutes to form a silicone ladder polymer film 14 having a film thickness of about 0.2 μm (FIG. 2B). Also here, the silicone ladder polymer having a hydroxyl group at the terminal shown in the chemical formula (3) uses the one produced by the method disclosed in JP-A-1-92224.
At this time, the reflectance from the lower ground was 10% or less.

Next, as in the case of the prior art, a photoresist layer 15 having a required film thickness was formed on the silicone ladder polymer film 14 (FIG. 3 (c)).

Next, as in the case of the prior art, the photoresist layer 15 was exposed by an i-line stepper of a mercury lamp and similarly developed to selectively form a resist pattern 15a. In the resist pattern 15a thus formed, no line width variation or reflective notching due to light interference was observed, as in the case of the first embodiment. Then, using the selectively formed resist pattern 15a as an etching mask, the silicone ladder polymer film 14 and the interlayer insulating film 13 are sequentially selectively processed and removed by, for example, dry etching, and patterned. The silicon ladder polymer film 14a and the interlayer insulating film 13a are left (FIG. 7 (d)).

Next, as in the case of the conventional technique, the resist pattern 15a used for the etching mask is removed ((e) in the figure), and finally, the patterned silicone ladder polymer film 14a is removed, for example, It is removed by wet etching ((f) in the same figure).

Third Embodiment . In the case of the method of the first embodiment, as means for exposing the photoresist layer,
The i-line stepper of the mercury lamp is used.
In the method of Examples, instead of this, an excimer laser stepper is used, and an aromatic compound as a dye for absorbing the light of the excimer laser is added to the silicone ladder polymer, and, for example, 1- Four
-It is used by including Benzoquinone. In the case of this third embodiment method, the manufacturing process is
It is almost the same as in the case of the embodiment method, and its operation and effect are almost the same.

Fourth Embodiment . In the case of the method of the first embodiment, as means for exposing the photoresist layer,
The i-line stepper of the mercury lamp is used.
In the example method, instead of this, g of the mercury lamp is used.
A line stepper is used, and a polyene compound as a dye for absorbing the light of the g-line is used for the silicone ladder polymer, for example, 4-tricyanovin.
It is used by containing ylaniline. Also, in the case of the method of the fourth embodiment, the manufacturing process is almost the same as that of the method of the first embodiment, and the operation and effect thereof are also almost the same.

Fifth embodiment . 3 (a) to 3 (e) are cross-sectional schematic views showing in sequence the main steps of the pattern forming method to which the fifth embodiment of the present invention is applied.

In the method of the fifth embodiment, first, as in the case of the method of the first embodiment, the metal layer 22 for forming wiring or elements is formed on the main surface of the substrate by the conventional technique. In addition, the semiconductor substrate 21 having the photoresist 23 formed on the metal layer 22 is prepared (see FIG.
(a)).

Next, on the photoresist 23 of the semiconductor substrate 21, a silicone ladder polymer having a weight average molecular weight of 100,000 shown in the chemical formula (3) and absorption near the i-line of a mercury lamp are absorbed. The butadiene cyano compound-based dye (containing 20% by weight with respect to the silicone ladder polymer) having anisole (adjusted to a concentration of 5% by weight) was spin-coated, and the coating was performed at 150 ° C. for 30 minutes and 2 times.
Heat treatment was sequentially performed at 50 ° C. for 60 minutes to form a silicone ladder polymer film 24 having a film thickness of about 0.2 μm (FIG. 2B). Here, again, as the silicone ladder polymer having a hydroxyl group at the terminal shown in Chemical formula (3), one produced by the method disclosed in JP-A-1-92224 is used. The reflectance of the silicone ladder polymer film 24 was 10% or less.

Next, as in the prior art, the photoresist layer 23 was exposed through the silicone ladder polymer film 24 by an i-line stepper of a mercury lamp. At this time, no foaming phenomenon was observed in the photoresist. Subsequently, the silicone ladder polymer film 24 was removed by, for example, wet etching ((c) in the same figure).

Then, as in the case of the conventional technique, the photoresist layer 23 was developed to selectively form a resist pattern 23a. Then, in the resist pattern 23a thus formed, no line width variation or reflective notching due to light interference was observed, as in the case of the first embodiment. Subsequently, using the resist pattern 23a selectively formed as described above as an etching mask, the metal layer 22 is selectively processed and removed by, for example, dry etching to form a metal layer 22a having a desired pattern shape as desired. ((D) in the figure), and then, as in the case of the conventional technique, the resist pattern 2 is formed.
By removing 3a, as a result, the metal layer 22a patterned on the main surface of the semiconductor substrate 21 as expected is obtained as a result (FIG. 6 (e)).

Sixth Embodiment . In the case of the method of the first embodiment, the weight average molecular weight shown in the chemical formula (2) is 10
However, in the method of the sixth embodiment, the weight average molecular weight is 100,000, the terminal is an ethoxy group, and the side chain is methyl. 750 ppm of a silane coupling agent (Vinyltrichlorosirane) for improving the adhesion to the base substrate is added to the base silicone ladder polymer and used.

[0045]

[Chemical 4] In the case of the method of the sixth embodiment, the manufacturing process is almost the same as that of the method of the first embodiment.
In this case, similar actions and effects are obtained, and the photochemical reaction in the photoresist film is mildened by reducing the light of the stepper to expose it, and the exposure time is lengthened to occur. It was possible to prevent foaming by extending the diffusion time of nitrogen.

[0046]

As described above in detail with reference to the embodiments, according to the method of the present invention, after the photoresist film is formed on the patterned layer such as the metal layer to be patterned, the photoresist is formed. While exposing and developing the film according to the required pattern to form a resist pattern,
In a pattern forming method for selectively removing and patterning a pattern formation layer using a resist pattern as a mask, an antireflection film at the time of exposure processing and a photoresist for a lower layer side or an upper layer side of a photoresist film. Since the silicone ladder polymer film represented by the formula (2) was used as the antifoaming film, the exposure process for the photoresist film was effectively performed, and the resist pattern was not foamed and the resist pattern was excellent and high. It has an excellent feature that it can be formed with high precision, and as a result, a device configuration suitable for high-density integration and multilayer wiring can be obtained.

[Brief description of drawings]

1 (a) to 1 (g) are schematic cross-sectional views sequentially showing main steps of a pattern forming method to which a first embodiment of the present invention is applied.

2 (a) to (f) are schematic cross-sectional views sequentially showing main steps of a pattern forming method to which a second embodiment of the present invention is applied.

3 (a) to 3 (e) are schematic cross-sectional views sequentially showing main steps of a pattern forming method to which a fifth embodiment of the present invention is applied.

4 (a) to 4 (e) are schematic cross-sectional views sequentially showing main steps of a pattern forming method according to a conventional example.

[Explanation of symbols]

1,11,21 Semiconductor substrate 2,12,22 Metal layer 2a, 22a Patterned metal layer 3,14,24 Silicone ladder polymer layer 3a, 14a, 24a Patterned silicone ladder polymer layer 4,15,23 Photoresist Layers 4a, 15a, 23a Resist pattern 13 Inter-layer insulating film 13a Patterned inter-layer insulating film

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshio Hayashi, 4-chome, Mizuhara, Itami City, Hyogo Prefecture, LS Electric Co., Ltd. LSE Research Institute (72) Inventor, Shinji Kishimura 4-chome, Mizuhara, Itami City, Hyogo Prefecture No. 1 Mitsubishi Electric Corporation LSI Research Center

Claims (7)

[Claims] 1. A resist film is formed on a pattern forming layer such as a metal layer to be patterned, and then the photoresist film is exposed and developed according to a required pattern to form a resist pattern. In the pattern forming method of using the resist pattern as a mask to selectively remove and pattern the layer to be patterned, a lower layer side of the photoresist film, or an upper layer side,
A pattern forming method, characterized in that a silicone ladder polymer film represented by the following formula (1) is formed as an antireflection film and a photoresist foaming preventing film at the time of exposure treatment. [Chemical 1] (Here, in the above formula, R1 is a phenyl group, a lower alkyl group, or a photosensitive group, which may be the same or different. R2 is a hydrogen atom, a lower alkyl group, or a photosensitive group. And may be the same or different, and n represents an integer of 20 to 1000.) 2. The silicone ladder polymer film is a spin coating film, and the silicone ladder polymer film contains a dye or compound that absorbs g-line or i-line of a mercury lamp or laser light. The pattern forming method according to claim 1, wherein: 3. The dye or compound contained in the silicone ladder polymer film is a high-purity dye, in particular, one having an impurity concentration of about 0.5 ppm or less such as heavy metal, alkali metal, alkaline earth metal, The pattern forming method according to claim 1, wherein an aromatic compound, a benzoxazole compound, a butadiene cyano compound, or a polyene compound is used. 4. The pattern forming method according to claim 1, wherein when the silicone ladder polymer film is used as an antireflection film, the reflectance from the pattern forming layer side is about 30% or less. 5. The pattern forming method according to claim 1, wherein when the silicone ladder polymer film is used as an antifoaming film, the reflectance from the pattern forming layer side is about 10% or less. 6. When the silicone ladder polymer film is used as a reflection and foaming prevention film, in order to obtain a reflectance of about 30% or less, and about 10% or less from the side of the pattern forming layer, the silicone ladder polymer film is used. 2. The pattern forming method according to claim 1, wherein the dye or the compound is contained in the ladder polymer film in an amount of about 5 to 20% by weight. 7. When the silicone ladder polymer film is used as a reflection and antifoaming film, the silicone ladder polymer film is used in order to improve the adhesiveness and adhesion to the patterned layer and the photoresist film. In contrast, 500 to 2000 p of silane coupling agent
The pattern forming method according to claim 1, wherein the pattern forming method is contained in about pm.