JP3340493B2 - Pattern forming method, method for forming photomask for phase shift method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming a pattern and a method for forming a photomask for a phase shift method using the same.

[0002]

2. Description of the Related Art In the field of lithography, various techniques for forming a fine resist pattern capable of coping with high integration of a semiconductor device have been proposed. Among them,
For example, see the literature (Proc. Of 1991 I
ntern.MicroProcess Conference), pp145-15
CARL (Chemical Amplifica) disclosed in 2)
There is a technology called “tion of Resist Lines”. This technology can either (1) expand the volume of this resist pattern by making it more silylatable by making the resist pattern formed by general lithography technology and make it thicker than before silylation, or (2). In this technique, the resist is silylated to increase the thickness of the exposed portion. In this technique, the space in the resist pattern can be narrowed by an amount corresponding to an increase in the thickness of the resist pattern by silylation. That is, a smaller hole pattern could be formed than a resist pattern formed only by exposure and development, and a line having a large line width (in other words, a line having a low line resistance) could be formed at the same pitch.

[0003]

However, in the case of the CARL technique described above, it is necessary to use a special resist for silylation. In the manufacture of semiconductor devices, it is often desirable to increase the thickness of a once formed resist pattern using a general-purpose material.

In the CARL technique described above, the resist pattern obtained is of the SiO ₂ type, so that, for example, S
When an attempt is made to etch the iO ₂ film, a selective ratio between the resist pattern and the object to be etched (SiO ₂ film) cannot be obtained. Therefore, when etching the SiO ₂ film, a so-called two-layer resist process in which another resist is formed below the resist to be silylated is required. From this point of view, a method is desired in which the once formed resist pattern can be thickened by a method other than silylation.

[0005] The present application has been made in view of such a point. Therefore, an object of the first invention of the present application is to increase the thickness of a pattern obtained by exposure and development to obtain a desired pattern with higher versatility. An object of the present invention is to provide a pattern forming method that can be performed. Also, the purpose of the second invention of this application is
An object of the present invention is to provide a method for forming a Rim-type photomask for a phase shift method using the method of the first invention. Another object of the third invention of the present application is to provide a method for forming a multistage phase shift photomask using the method of the first invention.

[0006]

According to the first aspect of the present invention, when a desired pattern is formed on a base, a predetermined pattern is formed on the base with respect to the desired pattern. Forming a first resist pattern containing a base having a related shape, and dissolving the solution by the action of a base on the base on which the first resist pattern has been formed so as to cover the first resist pattern; Second insolubilized in
The step of forming a layer of the resist pattern forming material of the second step, and at least a portion of the layer of the second resist pattern forming material from the interface with the first resist pattern to a predetermined thickness by the action of a base. Converting the resist pattern forming material into a denatured layer that is insoluble in the dissolving solution, and dissolving the non-denatured layer of the second resist pattern forming material on which the denatured layer is formed with the dissolving solution, Obtaining a pattern comprising a first resist pattern and a denatured layer as the pattern (1).

[0007] Here, the underlayer can be any one of those for which a pattern is to be formed. In addition, the first resist pattern having a predetermined relationship with the desired pattern is defined as a first resist pattern after the above-mentioned modified layer is formed and a pattern which is predetermined so that a desired pattern can be obtained by the modified layer. Say. For example, it may have a shape similar to a desired pattern. If there is a possibility that the first resist pattern may be dissolved by the second resist pattern forming material (for example, a solvent of the second resist pattern forming material), it is preferable to perform insolubilizing treatment on the first resist pattern. . This insolubilization process can be performed by performing a process such as applying heat or irradiating ultraviolet rays to the first resist pattern, preferably by performing it excessively.

In the first invention, when a desired pattern is formed on the base, a first resist pattern having a predetermined relationship with the desired pattern is formed on the base, A step of introducing, into the resist pattern, a factor selected from a group containing an acid, an acid generator or a base to insolubilize the second resist pattern forming material with respect to the solution, and completing the formation of the first resist pattern. Forming a layer of a second resist pattern forming material insolubilized by the factor so as to cover the first resist pattern on the base, and at least forming a layer of the second resist pattern forming material on the first resist pattern. Converting a portion from an interface with the first resist pattern to a predetermined thickness portion into a denatured layer that is insoluble in a solution of the second resist pattern forming material by the action of the factor; Dissolving a portion other than the modified layer of the layer of the second resist pattern forming material having the modified layer formed thereon with a dissolving solution to obtain a desired pattern, a pattern comprising the first resist pattern and the modified layer; It is characterized by including.

[0009]

[0010]

Further, the formation of the modified layer is performed by the first
It is preferable to apply heat to the sample after the formation of the pattern and the layer of the second pattern forming material, and to control the thickness of the modified layer by the conditions for applying the heat.

According to the second invention of this application, a phase shifter is provided along a light-shielding pattern for determining a transmission area inside the transmission area (in other words, at least a light-shielding pattern on the phase shifter is provided). A light-shielding pattern in which a part of the edge falls within the area of the phase shifter described above) a phase shifter is provided along a light-shielding pattern that determines a transmission area inside a transmission area, which is a so-called Rim type. In a method of forming a photomask for a phase shift method, a step of forming a thin film for forming a light shielding pattern on a phase shifter forming material for forming a phase shifter, and a step of forming a mask for forming a light shielding pattern on the thin film for forming a light shielding pattern First
Forming a light-shielding pattern by using the first resist pattern as a mask to obtain a light-shielding pattern by patterning a thin film for forming a light-shielding pattern;
Introducing a factor selected from a group containing an acid, an acid generator or a base into the resist pattern, the factor insolubilizing the second resist pattern forming material with respect to a solution, and forming a light-shielding pattern on the sample. On top, a layer of a second resist pattern forming material is formed so as to cover the first resist pattern.
Forming a second resist pattern forming material dissolving solution using at least a portion of the layer of the second resist pattern forming material from the interface with the first resist pattern to a predetermined thickness portion using the factor; And a step of converting the first resist pattern and the denatured layer from the first resist pattern and the denatured layer by dissolving a portion other than the denatured layer of the layer of the second resist pattern forming material having the denatured layer formed thereon. And a step of patterning a phase shifter forming material using the phase shifter forming mask pattern as a mask to obtain a phase shifter.

According to the third aspect of the present invention, there is provided a photomask for a phase shift method in which an edge portion of a phase shifter has a stepwise different thickness in order to make a phase shift amount of exposure light stepwise. Forming a first resist pattern as a mask for obtaining a first thickness portion of the phase shifter on a phase shifter forming material for forming a phase shifter; Etching a portion of the phase shifter forming material exposed from the first resist pattern to a second thickness using the pattern as a mask, and selecting the first resist pattern from a group containing an acid, an acid generator or a base. Introducing a factor for insolubilizing the second resist pattern forming material with respect to the dissolving solution, and covering the first resist pattern on the etched sample. Forming a layer of a second resist pattern forming material, and using at least a portion of the layer of the second resist pattern forming material from an interface with the first resist pattern to a predetermined thickness. Converting the second resist pattern forming material into a modified layer that is insoluble in a solution of the second resist pattern forming material; Dissolving to obtain a second resist pattern comprising a first resist pattern and a modified layer, and etching the phase shifter forming material to a third thickness or to the back surface using the second resist pattern as a mask And a step of performing

In implementing these photomask forming methods, the first resist pattern forming material and the second resist pattern forming material can be selected in the same manner as in the first invention.

[0015]

According to the structure of the first invention of this application, the interaction between the first resist pattern containing a predetermined factor and the layer of the second resist pattern forming material is used to form the first resist pattern. A modified layer as a new layer for thickening the first resist pattern is formed around the periphery. Since various factors can be considered at this time, it is possible to increase the thickness of the resist pattern once formed with more versatility. Further, since this modified layer can be formed in a self-aligned manner with respect to the first resist pattern, it is considered that a desired pattern is easily obtained.

Further, since the acid, acid generator, base, or mixing layer forming factor as a factor for forming the modified layer is a factor which can be easily controlled by heat, formation of the modified layer can be performed easily. In addition, the thickness control of the modified layer can be made practical.

According to the method for forming a phase shift photomask of the second invention of this application, a mask pattern for forming a phase shifter is formed based on this mask pattern after forming a mask pattern for forming a light shielding portion. It can be formed in an aligned manner.

Further, according to the photomask forming method for the phase shift method according to the third invention of the present application, a mask pattern for forming the thickest portion of the phase shifter is formed, and then, based on this mask pattern, Mask patterns for sequentially forming portions having different thicknesses can be formed in a self-aligned manner.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the first to third inventions of the present application will be described below with reference to the drawings. However, the drawings used in the description merely schematically show the dimensions, shapes, and arrangements of the components so that the present invention can be understood. Further, in each of the drawings, the same components are denoted by the same reference numerals. Further, the materials used, the amounts used, the devices used, the film thickness, the temperature, the time, and the like described in the following description are merely examples within the scope of these inventions.

1. Description of first invention 1-1. First Example First, a positive-type resist containing an acid generator was used as a first pattern forming material, and a chemically amplified resist that crosslinked by the action of an acid was used as a second pattern forming material. An example of forming a forming resist pattern will be described. 1 (A) to 1 (C) and FIG.
(A) and (B) are process drawings used for the explanation. In each case, the sample is shown by a cross-sectional view taken along the thickness direction of the substrate (the same applies to the following drawings).

A positive resist (i.e., a novolak-quinonediazide-based resist referred to as FHi-3950) containing 0.1 wt% of an onium salt as an acid generator 13 in this case on a silicon substrate 11 as an underlayer. A layer 15 of Fuji Hunt Co.) is formed (FIG. 1A).

Next, the resist layer 13 is subjected to a pre-exposure bake, followed by exposure and development to obtain a line and space pattern 15a as a first pattern.
In this embodiment, the width W _{1 of the} line portion and the width W of the space portion
₂ (see FIG. 1B) all form a 0.5 μm line and space pattern 15a.

Next, the sample on which the first pattern 15a has been formed is irradiated with ultraviolet rays having a wavelength of 200 to 400 nm (preferably ultraviolet rays having a shorter wavelength than the exposure light) so as to have an appropriate light amount. By this ultraviolet irradiation, the first pattern 15a becomes insoluble in a solvent of SAL-601 (described in detail later) as a second pattern forming material to be formed later. The acid generator 13 contained in the first pattern 15a emits an acid 13a by this ultraviolet irradiation (FIG. 1B). In FIG. 1B, the acid generator 13 and the acid 1 are shown for convenience of explanation of the principle of the present invention.
3a shows a schematic diagram in which the coexistence with
The state in the pattern 15a is not limited to this.

Next, a first pattern 15 is formed on the sample.
A layer 17 of Shipley's resist called SAL-601 is formed as a chemically amplified resist crosslinked by the action of an acid so as to cover a (FIG. 1C).

Next, the sample on which the SAL-601 layer 17 has been formed is heat-treated at 100 ° C. for 1 minute. In this heat treatment, the acid 13a generated in the first pattern 15a diffuses by a distance according to the heat treatment conditions of the layer 17 of SAL-601. Therefore, the acid 1 in the layer 17 of SAL-601
Since the portion which 3a reaches is crosslinked, this portion is SAL-6.
No. 01 is converted into a denatured layer 19 that is insoluble in a developing solution (solution) (FIG. 2A).

Next, SAL-6 on which the modified layer 19 is formed
01 other than the modified layer 19 is SAL-601.
And a desired line and space pattern 21 having a line portion composed of the first pattern 15a and the modified layer 19 is obtained (FIG. 2B).
The width of the line portion of the line-and-space pattern 21 was measured with a SEM ruler S-6100 (manufactured by Hitachi) and found to be 0.65 μm. Accordingly, the line portion of the first pattern 15a having a line portion width of 0.5 μm is set to be equal to 0. 0 under the condition of the first embodiment.
It can be seen that the thickness can be increased by 15 μm.

Note that, apart from the first embodiment, SAL-
The conditions of the heat treatment performed after the formation of the layer 17 of the layer 601 and before the development are set variously to form the patterns 21 respectively,
Inspection of the width of the line portion of the line and space pattern 21 in each case revealed that the thickness of the line portion (that is, the thickness of the denatured layer 19) can be controlled by changing the heat treatment temperature and the heat treatment time. .
For example, when the heat treatment at a temperature of 100 ° C. for 1 minute is changed to a temperature of 110 ° C. for 1 minute in the above embodiment, the width of the line portion becomes 0.7 μm, which is 0.2 μm with respect to the line width of the first pattern 15a. It turned out that I could get fat.

1-2. Second Embodiment In the above-described first embodiment, an acid generator (one factor) was previously included in a first pattern forming material, and the forming material was patterned to obtain a first pattern. However, the first pattern may be formed by patterning a first pattern forming material that does not include one factor in advance and then including one factor later. This second embodiment is an example. However, the second embodiment will also be described with an example in which a line and space pattern is formed. FIG. 3 (A) to (C)
FIG. 4 is a process drawing for explaining the main part.

First, an FHi-395 manufactured by Fuji Hunt Co., Ltd., which was also used in the first embodiment, was formed on a silicon substrate 11 as a base.
A resist layer 15 referred to as “0” is formed to a thickness of, for example, 1 μm (not shown). Next, the sample is heated on a hot plate at a temperature of 95 ° C. for 90 seconds to perform a pre-exposure bake, and then exposed by an i-line stepper NSRi7E (manufactured by Nikon). Next, this sample was placed on a hot plate for 1 hour.
After the exposure, baking is performed by heating at a temperature of 10 ° C. for 90 seconds, and then development is performed. As a result, the first pattern 15x (hereinafter, “preliminary pattern 15
x ". ) (FIG. 3A). In this case, the preliminary pattern 15x was a line-and-space pattern in which both the width of the line portion and the width of the space portion were 0.5 μm.

Next, a process of curing the preliminary pattern 15x is performed. This is Espacer 1 which will be used later
This is to prevent the shape of the preliminary pattern 15x from being distorted by 00 (details will be described later). In this embodiment, this curing treatment is performed at a wavelength of 220 to 4 from a mercury lamp.
While irradiating the sample with a 00 nm bright line,
Performed by heating to a temperature of ° C. This processing time is 2
Minutes. Irradiation with ultraviolet rays was performed by an apparatus (made by Ushio) called FX2000OV. In addition, when there is no fear of the pattern collapse of the preliminary pattern, the curing process is of course unnecessary.

Next, in order to include an acid in this case as one factor in the preliminary pattern 15x, the preliminary pattern 1
A layer 23 of another substance containing one factor 13 (in this case, acid) is formed on the sample on which the 5x has been formed (FIG. 3).
(B)). In this embodiment, this layer 23 was formed by applying an acid-containing conductive film forming material (manufactured by Showa Denko KK) called an escaper 100 at a coating condition of 2000 revolutions / minute. Next, this sample is heated on a hot plate at a temperature of 100 ° C. for 1 minute. Espercer 10
Since the acid in 0 diffuses into the preliminary pattern 15x in this heat treatment, the preliminary pattern 15x
(FIG. 3C). The unnecessary layer 23 of the spacer 100 is removed with water.

Thereafter, FIGS. 1B and 2 of the first embodiment.
Processing similar to the processing described using (B) is performed. Thereby, the first pattern can be thickened as desired.

1-3. Third Embodiment In the above-described first and second embodiments, an acid is used as one factor, and a resist that is cross-linked by the action of an acid is used as the second pattern forming material. The present invention is also realized when the second pattern forming material is made insoluble in the solution of the second pattern forming material by the action of the base. The third embodiment is an example. However, the third embodiment will also be described with an example in which a line and space pattern is formed. FIG. 4 is a process drawing for explaining the main part.

First, a preliminary pattern 15x is formed on the base 11 by the same procedure as that described with reference to FIG. 3A of the second embodiment, and further, the same procedure as that described in the second embodiment. The hardening process of this preliminary pattern 15x is performed (FIG. 4A).

Next, on this sample, one factor (base) 2
In this case, a liquid 27 containing hexamethyldisilazane, which is an amine-based substance (in this case, O
AP) is applied by a spin coating method and allowed to stand naturally (FIG. 4B). In this series of processing, hexamethyldisilazane as one factor 27 is introduced into the preliminary pattern 15x, so that the preliminary pattern 15x becomes the first pattern 15a containing hexamethyldisilazane as one factor ( (FIG. 4 (C)).

Thereafter, on this sample, a chemically amplified positive resist WKR-TP-1 (not shown) is used as a second pattern forming material which is insolubilized in a developing solution by the action of a base. Wako Pure Chemical Co., Ltd.), and then the entire surface of this resist was irradiated with the above-mentioned ultraviolet irradiation device FX-2000OV.
(Ushio) is used to irradiate ultraviolet rays with a wavelength of 220 to 400 nm. Subsequently, the sample was placed on a hot plate for 10 minutes.
Heat for 1 minute at a temperature of 0 ° C. and then develop with a developer.

Since the WKR-TP-1 resist is a positive type chemically amplified resist, an acid is generated in a portion irradiated with ultraviolet rays and this portion must be dissolved in a developing solution. If, as in the example, the entire surface is irradiated with ultraviolet rays and then developed, the resist layer should originally be completely dissolved. However, in the third embodiment, the first
In the pattern 15a, the hexamethyldisilazane (one factor) 27 diffuses into the layer of the positive resist WKR-TP-1 up to a distance corresponding to the heat treatment conditions in the heat treatment at 100 ° C. for 1 minute. In the region where hexamethyldisilazane is diffused, the hexamethyldisilazane deactivates the generated acid. For this reason, WKR-TP
The region of layer -1 where hexamethyldisilazane diffuses becomes insoluble in the developer of WKR-TP-1. That is, although the mechanism for forming the modified layer is different from the first and second embodiments, the modified layer can be obtained as in the first and second embodiments. Therefore, the first pattern 15a can be thickened by this modified layer.

1-4. Fourth Embodiment Pattern formation is performed in the same procedure as in the third embodiment, except that hexamethyldisilazane is introduced into the preliminary pattern 15x by blowing OAP vapor onto the base 11 on which the preliminary pattern 15x is formed. In this embodiment, the OAP vapor is blown by M
This was accomplished by placing OAP in a coater designated KII and bubbling with N ₂ (nitrogen) to produce OAP vapor.

In the case of the fourth embodiment as well, it was found that the first pattern could be thickened as in the third embodiment.

1-5. Fifth Embodiment Even when the first pattern forming material and the second pattern forming material are the same, the present invention can be realized by properly selecting materials and performing proper processing. The fifth embodiment is an example. In the fifth embodiment, a chemically amplified resist (made by Hoechst) which is a negative resist for i-line and is called AZIN-4 is used as the first and second pattern forming materials.

First, although not shown, AZIN-4 is applied to a predetermined thickness on a silicon substrate as a base, and then exposed and developed under predetermined conditions to form a line and space pattern as a first pattern. .

Next, the first pattern is again sufficiently irradiated with i-line. As a result, an acid as one factor is more sufficiently generated in the first pattern.

Next, the AZIN-
In order to prevent the first pattern from being attacked by 4, the sample is heated at a temperature of 180 ° C. for 1 minute to insolubilize the first pattern in the solvent of AZIN-4.

Next, an AZIN-4 layer is formed on the entire surface of the sample. Thereafter, the sample is heated at a temperature of 110 ° C. for 1 minute. The acid in the first pattern was this AZIN-4
Is diffused in the layer according to the heat treatment conditions. AZ
The portion of the IN-4 layer where the acid is diffused becomes a modified layer that is insoluble in the AZIN-4 developer. Thereafter, development is performed. The portion other than the modified layer of AZIN-4 is removed during development, and only the modified layer remains. Therefore, like the first to fourth embodiments, the first pattern can be thickened by this modified layer. In this case, the step of exposing the second pattern forming material can be omitted.

1-6. Sixth Embodiment In the above-described first to fifth embodiments, one factor such as an acid or a base is diffused from the first pattern side into a layer of a second pattern forming material containing the other factor, and these factors are diffused. The modified layer is formed by the interaction of the first pattern and the second pattern forming material. However, the modified layer may be formed by the interaction of the forming material in the boundary region between the first pattern and the second pattern forming material. it can. The sixth embodiment is an example. FIG.
(A)-(D) are the principal part process drawings used for the description.

In this case, a 0.5 μm line and space pattern is formed as the first pattern 15a using, for example, a resist FHi-3950 manufactured by Fuji Hunt on a silicon substrate 11 as a base (FIG. 5A). Next, on this sample, a layer 2 of PMMA dissolved in monochlorobenzene was formed as a layer 29 of a second pattern forming material.
9 is formed (FIG. 5B). Next, the sample is heated on a hot plate at a temperature of 110 ° C. for 5 minutes. In this heat treatment, the first pattern 15a (FHi-3950)
The mixing layer 31 is formed at the boundary between the layer 29 and the layer 29 obtained by dissolving PMMA in monochlorobenzene, so that the modified layer 31 composed of the mixing section 31 is formed.
Is obtained (FIG. 5 (C)). Next, the layer 29 of PMMA dissolved in monochlorobenzene is developed with monochlorobenzene. In this development, the mixing unit 31
Are not dissolved or hardly dissolved in monochlorobenzene, and remain, so that the first pattern 15a is thickened substantially by the thickness of the mixing portion 31, and as a result, a desired pattern 33 is obtained (FIG. 5D). . It is noted that the thickness of the first pattern 15a is substantially equal to the thickness of the mixing portion 31.
This is because the mixing portion generated on the side does not contribute to the pattern thickening. It was found that the line portion having a width of 0.5 μm under the conditions of the sixth embodiment became wider to a width of 0.6 μm.

1-7. Seventh Embodiment In the sixth embodiment, PMMA dissolved in monochlorobenzene is used as the second pattern forming material. In the seventh embodiment, instead, an aqueous solution of polyvinyl alcohol is used as the second pattern forming material, and the developing solution is water. Other than that, pattern formation was performed in the same procedure as in the sixth embodiment. Also in this case, it was found that the line portion having a width of 0.5 μm can be thickened to a width of 0.6 μm.

1-8. Eighth to Fourteenth Embodiments In each of the first to seventh embodiments described above, an example in which a line and space pattern is formed has been described. However, the method of the first to seventh embodiments is applicable to forming a pattern of another shape. Can also be applied. As an example, an example in which a hole pattern is formed using the method of the first embodiment will be described. FIGS. 6 (A) to 6 (C) and FIGS. 7 (A) and 7 (B) are process diagrams for explanation thereof.

Layer 1 of FHi-3950 (resist made by Fuji Hunt) containing 0.1% by weight of onium salt as acid generator 13 on, for example, silicon substrate 11 as a base
5 is formed (FIG. 6A).

Next, a pre-exposure bake is performed on the resist layer 13, and thereafter, exposure and development are performed to obtain a hole pattern 15a as a first pattern (FIG. 6B).
In this embodiment, the hole pattern 15a having a hole diameter φ (see FIG. 6B) of 0.5 μm is formed.

Next, the sample on which the first pattern 15a has been formed is irradiated with ultraviolet rays having a wavelength of 200 to 400 nm (preferably ultraviolet rays having a shorter wavelength than the exposure light) so as to have an appropriate light amount. By this ultraviolet irradiation, the first pattern 15a becomes insoluble in a solvent of SAL-601 (described in detail later) as a second pattern forming material to be formed later. The acid generator 13 contained in the first pattern 15a emits an acid 13a by this ultraviolet irradiation (FIG. 6B).

Next, a first pattern 15 is formed on this sample.
A layer 17 of SAL-601 is formed as a chemically amplified resist that is cross-linked by the action of an acid so as to cover “a” (FIG. 6C).

Next, the sample on which the SAL-601 layer 17 has been formed is heat-treated at 100 ° C. for 1 minute. In this heat treatment, the acid 13a generated in the first pattern 15a diffuses by a distance according to the heat treatment conditions of the layer 17 of SAL-601. Therefore, the acid 1 in the layer 17 of SAL-601
Since the portion which 3a reaches is crosslinked, this portion is SAL-6.
No. 01 is converted to a denatured layer 19 which is insoluble in a developing solution (solution) (FIG. 7A).

Next, the SAL-6 on which the modified layer 19 is formed
01 other than the modified layer 19 is SAL-601.
To obtain a desired hole pattern 35 composed of the first pattern 15a and the modified layer 19 (FIG. 7B). The diameter of the hole portion of the hole pattern 35 was measured by a SEM ruler S-6100 (manufactured by Hitachi) and found to be 0.35 μm. Therefore, under the condition of the eighth embodiment, the diameter of the hole of the first pattern 15a, whose diameter was 0.5 μm, was set to 0.
It can be seen that it can be reduced by 15 μm (in other words, the wall can be thickened by 0.15 μm).

In the eighth embodiment, the SAL
It was found that the thickness of the denatured layer 19 can be controlled and the size of the hole of the hole pattern 35 can be controlled by variously changing the conditions of the heat treatment performed after the formation of the layer 17 of −601 and before the development.

As the ninth to fourteenth embodiments, the hole patterns were formed by the respective methods of the second to seventh embodiments, and the diameter of the hole portion of the hole pattern was reduced as in the second embodiment. It turns out that it is possible.

2. Description of Second Invention Next, an example of forming a Rim-type photomask for a phase shift method using the pattern forming method of the first invention will be described. This corresponds to, for example, the first to seventh aspects of the first invention.
It can be formed by any method of the embodiment. Here, an example in which the photomask is formed by the method of the second embodiment and the method of the fifth embodiment of the first invention will be described.

2-1. First Embodiment of the Second Invention First, an example in which a Rim-type photomask is formed by the method of the second embodiment of the first invention (a method using the spacer 100) will be described. However, here, a photomask for a hole pattern (see a plan view and a cross-sectional view in FIG. 10B).
An example of forming is described. 8 to 10 are process diagrams for the explanation. However, in each of the figures, only the region where the edge portion of the phase shifter is formed is shown.

First, a blank 49 having a conductive film 43, an SOG film 45 as a phase shifter forming material, and a chromium film 47 as a light shielding pattern forming thin film on a quartz glass substrate 41 as a photomask forming substrate in this order. Prepare The conductive film 43 is for preventing charge-up in the resist during electron beam drawing. next,
On the chromium film 47 of the blanks 49, a layer 51 of an electron beam resist (manufactured by Toso) called CMS-EX in this case is formed as a first pattern forming material (FIG. 8A).

Next, after a pattern is drawn on the electron beam resist layer 51 by an electron beam, the resist layer is developed to form a first pattern 5 as a light shielding pattern forming mask.
The first pattern 51b (hereinafter referred to as the “preliminary pattern 51”) which is 1b and does not yet include one of the factors referred to in the present invention.
It is called b. ) Is obtained (FIG. 8B). In this embodiment, a preliminary pattern 51b having a hole 51a having a side of 3 μm (3 μm square) is formed.

Next, using the preliminary pattern 51b as a mask, the light shielding pattern forming thin film 47 is selectively removed to form a light shielding pattern (light shielding portion) 47a (FIG. 8C).

Next, a layer 23 of the spacer 100 is formed on the sample by spin coating. Next, the sample is heated at a temperature of 110 ° C. for 2 minutes. Espercer 1
In this heat treatment, the acid in
Since the preliminary pattern 51b is diffused inward, the preliminary pattern 51b becomes the first pattern 51x containing an acid which is one factor (FIG. 9).
(A)). The unnecessary layer 23 of the spacer 100 is removed with water.

Next, a first pattern 51x is formed on the sample.
The layer 17 of SAL-601 is formed so as to cover (FIG. 9B).

Next, the sample on which the SAL-601 layer 17 has been formed is heat-treated at 110 ° C. for 5 minutes. The acid 13a in the first pattern 51x is formed by SA in this heat treatment.
The distance is diffused into the layer 17 of L-601 according to the heat treatment condition. Therefore, the acid 13a of the layer 17 of SAL-601
Is cross-linked, so this part is SAL-601
Is converted into a denatured layer 19 which is insoluble in the developing solution (dissolved solution) (FIG. 9C).

Next, SAL-6 on which the modified layer 19 is formed
01 other than the modified layer 19 is SAL-601.
To obtain a desired pattern (a phase shifter forming mask pattern) 53 composed of the first pattern 51x and the modified layer 19 (FIG. 9D). In addition,
The side of the hole of the pattern 53 is 2.2 μm (2.2 μm).
m □).

Next, using the pattern 53 as a mask, the SOG film as the phase shifter forming material 45 is selectively removed by dry etching to obtain a phase shifter 45a (FIG. 1).
0 (A)). In addition, when the sample before performing this etching was observed, SAL-601 was slightly left on the SOG film. This is probably because the acid in the spacer 100 remained in the SOG film during the processing of the spacer 100 and acted on the SAL-601 to form a thin modified layer on the SOG film. However, since this was slight, patterning of the SOG film could be performed without any problem.

Next, the pattern 53 is removed. Thus, a Rim-type photomask 55 for forming a hole pattern is obtained (FIG. 10B).

As is clear from the description of this embodiment, according to the method for forming the phase shift photomask of the second invention, the light-shielding pattern and the phase shifter of the Rim-type photomask can be formed in a self-aligned manner.

Further, the photomask forming method of the above-described embodiment is modified such that the phase shifter forming material is the photomask forming substrate 41 itself as shown in FIG. A phase shifter 45a, and
R of a type having a light shielding portion 47a at a predetermined portion on the substrate 41
It has been found that a desired photomask 57 can be obtained also when applied to the case of forming an im-type photomask 57.
In this case, SAL-601 did not remain on the photomask-forming substrate 41 probably because no acid was introduced from the spacer 100 into the substrate 41.

In the above embodiment, the preliminary pattern 51
b is used as a mask to etch the chromium film 47, and then an acid is introduced into the preliminary pattern 51b using the spacer 100.
Before etching the first pattern 51b, an acid is introduced into the preliminary pattern 51b using the spacer 100 to obtain a first pattern 51x, and the chromium film 47 is formed using the first pattern 51x as a mask.
May be etched.

2-2. Second Embodiment of the Second Invention Next, an example in which a Rim-type photomask is formed by the method of the fifth embodiment of the first invention (a method of using a chemically amplified resist for both the first and second pattern forming materials). Will be described.
This description will be made with reference to FIGS.

First, a conductive film 4 is formed on a quartz glass substrate 41.
3. A blank 49 having an SOG film 45 as a phase shifter forming material and a chromium film 47 as a light shielding pattern forming thin film in this order is prepared. And this blanks 4
9 on the chromium film 47 of No. 9 as a first pattern forming material.
The layer 61 of L-601 is formed (FIG. 12A). next,
An image is drawn on this layer 61 with an electron beam, and then this layer 61 is developed to obtain a first pattern 61b as a light-shielding pattern forming mask (FIG. 12B). Since the first pattern 61b is made of a chemically amplified resist, it contains an acid generator. In this embodiment, the first pattern 61b has a hole 61a having a side of 3 μm (3 μm square). Next, using the first pattern 61b as a mask, the light-shielding pattern forming thin film 47 is selectively removed to form a light-shielding pattern 47a.
Next, this sample is heated at a temperature of 180 ° C. for 5 minutes. This heat treatment allows the acid 13a to be present in the SAL-601 pattern.
Are sufficiently generated, so that a first pattern 61x containing an acid is obtained (FIG. 12C). Next, SAL is put on this sample again.
A layer 63 of -601 is formed (FIG. 13A). Then, the sample is heated at a temperature of 120 ° C. for 10 minutes. The acid in the first pattern 61x is SAL-6 in this heat treatment.
01 is diffused to the layer 63 side of the SAL-601.
The region where the acid is diffused becomes the denatured layer 19 (FIG. 13).
(B)). Next, the layer 63 of SAL-601 is removed with a developer. Thus, a desired pattern 65 composed of the first pattern 61x and the modified layer 19 is obtained (FIG. 13C).

Thereafter, using the pattern 65 as a mask, the SOG film 45 as a phase shifter forming material is selectively removed to obtain a phase shifter 45a, and further, by removing the pattern 65, a desired photomask is obtained.

The method of the second embodiment can be applied to the formation of the photomask described with reference to FIG. In the second embodiment, as described with reference to FIGS. 12B and 12C, the chromium film 4 is formed using the pattern 61b as a mask.
After etching No. 7, this sample was subjected to a heat treatment to sufficiently generate an acid to obtain a pattern 61x. However, in some cases, before etching the chromium film 47, the sample is subjected to a heat treatment to generate an acid in the
1x may be obtained and then the chromium film may be etched. Further, since the pattern 61b is a chemically amplified resist in the first place, it may not be necessary to perform a heat treatment before applying the SAL-601 as the second pattern forming material on the pattern 61b.

3. Description of Third Invention Next, an example of forming a multi-stage photomask for a phase shift method using the pattern forming method of the first invention will be described. This multi-stage type can also be formed by the method of any of the first to seventh embodiments of the first invention as in the case of the second invention. Here, an example in which the photomask is formed by the method of the second embodiment and the method of the fifth embodiment of the first invention will be described. The multi-stage photomask for the phase shift method is such that a portion having a different thickness is provided stepwise at the edge of the phase shifter. When the edge of the phase shifter is on the light transmitting region of the photomask without the multi-stage type, the light intensity is significantly reduced at the edge line and the edge line is transferred to the resist, but the multi-stage type can avoid this problem. .

3-1. First Embodiment of the Third Invention First, an example in which a multi-stage photomask is formed by the method of the second embodiment of the first invention (a method using the spacer 100) will be described. 14 to 16 are process diagrams provided for the description. However, in each of the figures, only the region where the edge portion of the phase shifter is formed is shown.

First, a blank 49 having a conductive film 43 and a SOG film 45 as a phase shifter forming material in this order on a quartz glass substrate 41 as a photomask forming substrate is prepared. In this case, CMS is used as a first pattern forming material on the chromium film 47 of the blanks 49.
-An electron beam resist called EX (manufactured by Toso)
A first pattern 71 for obtaining a portion of the phase shifter having a first thickness, which does not include one factor yet referred to in the present invention (hereinafter referred to as “preliminary pattern 7”).
One. ) Is obtained (FIG. 14A). In this embodiment, the preliminary pattern 71 is a line pattern having a width of 1 μm.

Next, using the preliminary pattern 71 as a mask, the SOG film 45 as a phase shifter forming material is formed to a predetermined thickness d.
_{One is} removed by a known suitable method. This gives a first thickness t ₁ part 45a of the phase shifter (FIG. 14
(B)).

Next, a layer 23 of the spacer 100 is formed on this sample by spin coating (FIG. 14).
(C)). Next, the sample is heated at a temperature of 110 ° C. for 3 minutes. Since the acid 13a in the spacer 100 diffuses into the preliminary pattern 71 in this heat treatment, the preliminary pattern 71 becomes a first pattern 71x containing an acid which is one of the factors (FIG. 15A). The unnecessary layer 23 of the spacer 100 is removed with water.

Next, a first pattern 71x is placed on this sample.
Is formed to cover the SAL-601. Next, the sample on which the layer 17 of SAL-601 was formed was
Heat-treat at a temperature of 0 ° C. for 10 minutes. First pattern 71
In this heat treatment, the acid 13a in x diffuses into the SAL-601 layer 17 by a distance according to the heat treatment conditions. As a result, the portion of the layer 17 of the SAL-601 that is exposed to the acid 13a is crosslinked, and this portion is converted into a modified layer 19 that is insoluble in a developing solution (solution) of the SAL-601 (FIG. 15).
(B)).

Next, SAL-6 on which the modified layer 19 is formed
01 other than the modified layer 19 is SAL-601.
To obtain a second pattern 73 composed of the first pattern 71x and the denatured layer 19 for obtaining the second thickness portion of the phase shifter (FIG. 15C).

Next, obtain a second thickness t ₂ parts 45b of the pattern 73 and the phase shifter forming material 45 a is SOG film again selectively removed as a mask a phase shifter (FIG. 16 (A)) . In this case, unnecessary portions of the SOG film are removed until the conductive film 43 is exposed. Thus the phase shifter 45x with different portions of stepwise thickness of thicknesses t ₁ and t ₂ in the edge portion is obtained. Here, the thicknesses t ₁ and t ₂ can be arbitrarily determined depending on the design. In this case, a phase difference of, for example, 90 degrees can be given to the exposure light in the thickness t ₂ portion. It is preferable that each of the thicknesses t ₁ is such that the exposure light can be given a phase difference of 180 degrees, for example.

Next, the second pattern 73 is removed. As a result, a multi-stage phase shift photomask 75 is obtained.

As is clear from the description of this embodiment, according to the method for forming a photomask for a phase shift method of the third invention, it is possible to form, in a self-aligned manner, portions having different thicknesses of phase shifters of a multistage photomask. Understand.

In the above embodiment, the preliminary pattern 71
Is used as a mask to etch portions other than the first thickness portion of the phase shifter forming material.
The acid was introduced into the preliminary pattern 71 using the spacer 100 before the phase shifter forming material was etched in some cases, and the first pattern 71x was obtained. Pattern 71
The phase shifter forming material may be etched using x as a mask.

When it is desired to further form a portion having a different thickness at the edge of the shifter, the etching of the SOG film after the formation of the second pattern is stopped halfway, and then the second pattern is removed. The third invention may be repeated from the step of forming the first pattern.

Also, in the case of the third invention, it can be applied to the formation of a multi-stage photomask in the case where the phase shifter forming material is the quartz glass substrate 41 itself.

3-2. Second Embodiment of Third Invention Next, an example in which a multi-step photomask is formed by the method of the fifth embodiment of the first invention (a method of using a chemically amplified resist for both the first and second pattern forming materials). Will be described. This description will be made with reference to FIGS.

First, a conductive film 4 is formed on a quartz glass substrate 41.
3. A blank 49 having an SOG film 45 as a phase shifter forming material in this order is prepared. Then, S is formed on the SOG film 45 which is the phase shifter forming material of the blanks 49.
Using AL-601, a first pattern 77 is formed as a mask for obtaining a portion of the phase shifter having the first thickness (FIG. 17A).

Next, using the mask 77 as a mask, the SOG film 45 as a phase shifter forming material is removed by a known thickness by a predetermined thickness d ₁ . This gives a first thickness t ₁ part 45a of the phase shifter (FIG. 17
(B)). Since the first pattern 77 is made of a chemically amplified resist, it contains an acid generator.

Next, this sample is heated at a temperature of 180 ° C. for 3 minutes. By this heat treatment, the acid 13a is sufficiently generated in the pattern 77 of the SAL-601, so that a first pattern 77x containing an acid is obtained (FIG. 17C). Next, a layer 79 of SAL-601 is formed again on this sample.
(A)). Then, the sample is heated at a temperature of 120 ° C. for 10 minutes. Since the acid in the first pattern 77x diffuses to the layer 79 side of SAL-601 in this heat treatment, SAL
The region where the acid was diffused in the layer 79 of -601 is the modified layer 19
(FIG. 18B). Next, the layer 79 of SAL-601 is removed with a developer. As a result, a second pattern 81 composed of the first pattern 77x and the modified layer 19 for obtaining the second thickness portion of the phase shifter is obtained (FIG. 18C).

Thereafter, using this pattern 81 as a mask, the SOG film 45 as a phase shifter forming material is selectively removed to obtain a second thickness portion 45b of the phase shifter.

In the second embodiment of the third invention, as described with reference to FIGS. 17B and 17C, the sample is subjected to a heat treatment after etching the shifter forming material 45 using the pattern 77 as a mask. Then, the acid was sufficiently generated to obtain a pattern 77x. However, in some cases, before etching the shifter forming material 45, the sample may be heat-treated to generate an acid in the pattern 77 to obtain the pattern 77x, and then the shifter forming material 45 may be etched.
Furthermore, since the pattern 77 is a chemically amplified resist in the first place, it may not be necessary to perform a heat treatment before applying the SAL-601 as the second pattern forming material on the pattern 77.

[0094]

As is apparent from the above description, according to the pattern forming method of the first invention of the present application, the first pattern including a predetermined factor and the first pattern formed so as to cover the first pattern and including the predetermined factor. A modified layer as a new layer for thickening the first pattern can be formed around the first pattern by utilizing the interaction of each factor with the layer of the second pattern forming material. Since various combinations of these factors are conceivable, thickening the resist pattern once formed can be performed with more versatility. Further, this modified layer can be formed in a self-aligned manner with respect to the first pattern. Therefore,
For example, if the first pattern is set as a fine pattern of the limit level of the conventional exposure apparatus and the present invention is applied to the first pattern to make the first pattern thicker, the first pattern becomes finer than the resolution limit of the conventional exposure apparatus. A simple pattern can be formed with good versatility using a conventional technique.

The acid, acid generator, base, or mixing layer forming factor, which is a factor for forming the modified layer, is a factor that can be easily controlled by heat, so that the modified layer can be easily formed. In addition, the thickness control of the modified layer can be made practical.

According to the method of forming a photomask for a phase shift method of the second invention of this application, a Rim-type photomask can be formed easily and with the effects of the first invention.
According to the method of forming a photomask for a phase shift method according to the third invention of this application, a multi-stage photomask can be formed easily and with the effects of the first invention.

[Brief description of the drawings]

FIG. 1 is a process chart for explaining a first embodiment of the first invention.

FIG. 2 is a process drawing following FIG. 1 for explaining the first embodiment of the first invention.

FIG. 3 is a process chart for explaining a main part of a second embodiment of the first invention.

FIG. 4 is a process chart for explaining a main part of a third embodiment of the first invention. It is a principal part perspective view with which description of Example of 2nd invention is provided.

FIG. 5 is a process chart for explaining a sixth embodiment of the first invention.

FIG. 6 is a process chart for explaining an eighth embodiment of the first invention.

FIG. 7 is a process drawing following FIG. 6 for describing an eighth embodiment of the first invention.

FIG. 8 is a process chart for explaining the first embodiment of the second invention.

FIG. 9 is a process drawing following FIG. 8 for explaining the first embodiment of the second invention.

FIG. 10 is a process drawing following FIG. 9 for explaining the first embodiment of the second invention;

FIG. 11 is an explanatory diagram of another example of the Rim photomask.

FIG. 12 is a process chart for explaining a second embodiment of the second invention.

FIG. 13 is a diagram for explaining a second embodiment of the second invention;
FIG.

FIG. 14 is a process chart for explaining the first embodiment of the third invention.

FIG. 15 is a diagram for explaining the first embodiment of the third invention;
FIG.

FIG. 16 is a view for explaining the first embodiment of the third invention.
FIG.

FIG. 17 is a process chart for explaining a second embodiment of the third invention.

FIG. 18 is provided for describing a second embodiment of the third invention.
FIG.

[Explanation of symbols]

11: Front substrate 13: One factor (for example, acid generator) 13a: One factor (for example, acid) 15: First pattern forming material 17: Layer of predetermined second pattern forming material 19: Modified layer 21: Desired pattern 25: One factor (for example, alkali) 31: Modified layer (mixing portion)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-5-241348 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G03F 1/00-1/16

Claims (9)

(57) [Claims] A step of forming a first resist pattern including a base in a predetermined relationship with respect to the desired pattern on the base to form a desired pattern on an underlayer; A layer of a second resist pattern forming material which is insolubilized in a solution by the action of the base is formed on the base on which the formation of the first resist pattern is completed so as to cover the first resist pattern. And at least a layer of the second resist pattern forming material,
Converting the portion from the interface with the first resist pattern to a predetermined thickness portion into a modified layer insoluble in a solution of the second resist pattern forming material by the action of the base; Is formed by dissolving a portion of the layer of the second resist pattern forming material other than the denatured layer with the dissolving solution,
Obtaining a pattern comprising the first resist pattern and the denatured layer as a desired pattern. A step of forming a first resist pattern having a predetermined relationship with the desired pattern on the base when forming a desired pattern on an underlayer; Introducing a factor selected from the group including an acid, an acid generator or a base, for insolubilizing the second resist pattern forming material with respect to a solution, and the step of forming the first resist pattern. Forming a layer of a second resist pattern forming material insolubilized by the factor on the lower ground so as to cover the first resist pattern; and at least a layer of the second resist pattern forming material,
Converting a portion from the interface with the first resist pattern to a predetermined thickness portion into a modified layer insoluble in a solution of the second resist pattern forming material by the action of the factor; Is formed by dissolving a portion other than the modified layer of the layer of the second resist pattern forming material formed with
Obtaining a pattern comprising the first resist pattern and the denatured layer as a desired pattern. 3. The pattern forming method according to claim 2, wherein the factor is an acid or an acid generator, and the second resist pattern forming material is a material that is made insoluble in the solution by the action of an acid. Characteristic pattern formation method. 4. The pattern forming method according to claim 2, wherein the factor is a base, and the second resist pattern forming material is a material insoluble in the dissolving solution by the action of the base. Forming method. 5. The pattern forming method according to claim 1, wherein the forming of the denatured layer includes applying heat to the sample on which the first resist pattern and the second resist pattern forming material have been formed. A pattern forming method, wherein the thickness of the denatured layer is controlled by applying the heat. 6. A method of forming a phase shift photomask having a phase shifter along a light-shielding pattern for determining a transmission area inside a transmission area, comprising: forming a light-shielding pattern on a phase shifter forming material for forming a phase shifter. Forming a first resist pattern as a light-shielding pattern forming mask on the light-shielding pattern forming thin film; and forming the light-shielding pattern using the first resist pattern as a mask. A step of patterning a thin film for forming a pattern to obtain a light-shielding pattern, and a dissolving solution of a second resist pattern forming material selected from a group containing an acid, an acid generator or a base in the first resist pattern Introducing a factor that insolubilizes the first resist pattern on the sample on which the light-shielding pattern has been formed. A layer of the second resist pattern forming material, a step of forming, in at least the second resist pattern forming material layer,
Converting from the interface with the first resist pattern to a predetermined thickness portion into a denatured layer that is insoluble in a solution of the second resist pattern forming material by using the factor; Dissolving a portion other than the modified layer of the layer of the second resist pattern forming material having the layer formed thereon with the solution to obtain a phase shifter forming mask pattern including the first resist pattern and the modified layer; Patterning the phase shifter forming material using the phase shifter forming mask pattern as a mask to obtain a phase shifter. 7. A method for forming a phase shift photomask in which an edge portion of a phase shifter has a stepwise different thickness in order to make a phase shift amount of exposure light stepwise, comprising: Forming a first resist pattern as a mask for obtaining a portion of the phase shifter having a first thickness on the phase shifter forming material; and forming the phase shifter forming material using the first resist pattern as a mask. Etching a portion exposed from the first resist pattern to a second thickness; and a second resist selected from a group containing an acid, an acid generator or a base in the first resist pattern. A step of introducing a factor for insolubilizing the resist pattern forming material with respect to the dissolving solution; and forming the second resist pattern on the etched sample so as to cover the first resist pattern. A layer of resist pattern formation material, a step of forming, a layer of at least the second resist pattern forming material,
Converting from the interface with the first resist pattern to a predetermined thickness portion into a denatured layer that is insoluble in a solution of the second resist pattern forming material by using the factor; A portion other than the modified layer of the layer of the second resist pattern forming material on which the layer is formed is dissolved with the dissolving solution, and a second layer composed of the first resist pattern and the modified layer is formed.
A phase shift method comprising: a step of obtaining a resist pattern of step (a); and a step of etching the phase shifter forming material to a third thickness or to a rear surface using the second resist pattern as a mask. Of forming a photomask for use. 8. The method for forming a phase shift method photomask according to claim 6, wherein the phase shifter forming material is a photomask forming substrate or a phase shifter forming material formed on the photomask forming substrate. A method for forming a photomask for a phase shift method, wherein the photomask is formed as a thin film. 9. The method for forming a photomask for a phase shift method according to claim 6, wherein the formation of the denatured layer is performed by the method according to claim 1.
A method for forming a photomask for a phase shift method, characterized by using the method described in (1).