TW201937292A - Positive-type resist composition, resist film formation method, and laminate production method - Google Patents

Abstract

A positive-type resist composition containing: a polymer which contains a component at a content of 90% or more, wherein the component contains an [alpha]-chloroacrylic acid ester unit and an [alpha]-alkylstyrene unit and has a molecular weight of more than 70000; and a solvent which comprises at least one component selected from cyclopentanone, methyl 3-methoxypropionate and methyl crotonate.

Description

Positive photoresist composition, photoresist film forming method and method of manufacturing the same

The present invention relates to a positive-type photoresist composition, a method for forming a photoresist film, and a method for producing a stacked body, and more particularly to a positive-type photoresist composition, a method for forming a photoresist film using the positive-type photoresist composition, and the use thereof A method of manufacturing a stack of a photoresist film forming method.

Conventionally, in the field of semiconductor manufacturing, short-wavelength light such as electron beam or extreme ultraviolet ray (EUV) or ultraviolet light (hereinafter, the combination of free radiation and short-wavelength light is called "free radiation, etc." The polymer which cuts the main chain and increases the solubility in the developing solution by irradiation is used as a main-chain-cut type positive resist.

Further, for example, Patent Document 1 discloses a positive resist formed of a copolymer of α-methylstyrene-α-chloroacrylic acid methyl ester containing α-methylstyrene unit and α-chloromethyl acrylate unit. As a high-sensitivity main chain cut-off type positive resist.

"Patent Literature"
Patent Document 1: Japanese Patent Laid-Open Publication No. H8-3636

Here, in the formation of the photoresist film, a pre-baking step of heating the coating film formed by applying the positive-type photoresist composition onto the workpiece is performed. The polymer contained in the photoresist film heated in the pre-baking step may have a small molecular weight due to heating. In this case, sometimes a pattern of a desired shape may not be formed in the formed photoresist film. As a countermeasure against this point, it has been considered to incorporate a polymer having a relatively large molecular weight into a positive-type photoresist composition.

However, the positive-type photoresist composition obtained by dissolving a polymer having a relatively large molecular weight in a composition as described in Patent Document 1 in a solvent such as anisole which has been conventionally used, has a coating property. There is room for improvement on the spot.

Moreover, in recent years, it has become a diversified material of a workpiece. Among these, materials which are likely to deteriorate or deteriorate due to exposure to high heat are also included. Therefore, it is required to expand the heating temperature and the heating time in the pre-baking process, that is, the pre-baking conditions, to the low temperature region side. In other words, there is a need for a positive-type photoresist composition which can sufficiently improve the adhesion between the photoresist film and the workpiece even when the pre-baking step is performed at a relatively low heating temperature.

Accordingly, an object of the present invention is to provide a positive type which can improve the adhesion between a photoresist film and a workpiece even when a pre-baking step is carried out in a relatively low temperature range of, for example, 170 ° C. Photoresist composition.

Further, an object of the present invention is to provide a method for forming a photoresist film which can improve the adhesion between a photoresist film formed by a prebaking step and a workpiece.

Further, an object of the present invention is to provide a method for producing a laminate having high adhesion between a photoresist film formed by a prebaking step and a light shielding layer.

The present inventors have devoted themselves to research to achieve the above object. Then, the present inventors have found that a positive-type resist having a main chain-cut type including a "designated polymer having a ratio of a component having a molecular unit exceeding 70,000 and having a molecular weight of more than 70,000" and a "specified solvent" is used. The composition has a high adhesion between the photoresist film and the workpiece obtained by performing a pre-baking step in a temperature range lower than the pre-baking temperature of the conventional positive-type photoresist composition. Furthermore, the inventors have found that such a positive resist composition is also excellent in coatability. The present inventors completed the present invention based on these new findings.

That is, in order to successfully solve the above problems, the positive resist composition of the present invention comprises a positive photoresist composition of a polymer and a solvent, characterized in that the polymer contains an α-chloroacrylate unit. The ratio of the component having an α-alkylstyrene unit and having a molecular weight of more than 70,000 is 90% or more, and the solvent contains at least one selected from the group consisting of cyclopentanone, methyl 3-methoxypropionate, and methyl crotonate.

A positive resist composition comprising "a polymer having a specified molecular weight distribution of a specified monomer unit" and a "specified solvent" is excellent in coatability, and a positive resist composition is used. The pre-baking temperature of the conventional positive-type photoresist composition is also high in the temperature range of the lower temperature, and the photoresist film obtained by performing the pre-baking process has high adhesion to the workpiece.

Further, in the positive resist composition of the present invention, the ratio of the component having a molecular weight of more than 80,000 of the polymer is preferably 80% or more. When the ratio of the component having a molecular weight of more than 80,000 is 80% or more, the decrease in the molecular weight of the polymer in the obtained photoresist film can be effectively suppressed.

Further, the present invention is directed to a method for forming a photoresist film which forms a photoresist film using any of the above-described positive-type photoresist compositions for the purpose of smoothly solving the above problems, and is characterized in that: And a pre-baking step of applying the positive-type photoresist composition to the workpiece and a pre-baking step of heating the coated positive-type photoresist composition, wherein the temperature P (° C.) of the following formula (1) is satisfied. And heating in the aforementioned pre-baking step at time t (minutes).
-0.4P+52≦t・・・(1)

If a specified type of polymer having a specified monomer unit is used as the main-type cut-off type positive resist, and a pre-baking process is performed under specified conditions, the photoresist film formed by the pre-baking process can be improved and processed. The closeness of the object.

Here, in the method for forming a photoresist film of the present invention, the time t is preferably more than 1 minute and not more than 30 minutes. In the heating in the pre-baking step, if the time t exceeds 1 minute and 30 minutes or less, the adhesion between the photoresist film formed by the pre-baking step and the workpiece can be more surely improved.

Further, the present invention has a method for manufacturing a stacked body of the present invention, comprising a substrate, a light shielding layer formed on the substrate, and a method of manufacturing a stacked body of a photoresist film formed on the light shielding layer. It is characterized in that the photoresist film is formed by any of the above-described photoresist film forming methods. When the photoresist film is formed by any of the above-described photoresist film formation methods, a laminate having high adhesion between the photoresist film formed by the prebaking step and the light shielding layer can be obtained.

The positive-type photoresist composition of the present invention is formed by a pre-baking process in which a pre-baking process is performed at a lower temperature than a pre-baking temperature of a conventional positive-type photoresist composition, and the film is formed. It is excellent and excellent in coating properties.

Further, according to the method for forming a photoresist film of the present invention, the adhesion between the photoresist film formed by the prebaking step and the workpiece can be improved.

Further, according to the method for producing a stacked body of the present invention, the adhesion between the photoresist film formed by the prebaking step and the light shielding layer can be improved.

The embodiments of the present invention are described in detail below.

Here, the positive resist composition of the present invention can be used in the method of forming a photoresist film of the present invention. In the method for forming a photoresist film of the present invention, a photoresist film used for forming a photoresist pattern in a process of a printed substrate such as a build-up substrate can be formed. Further, in the method of manufacturing a stacked body of the present invention, a stacked body used for forming a photoresist pattern in a process of a printed substrate such as a build-up substrate can be manufactured.

Further, the polymer contained in the positive-type photoresist composition of the present invention can be suitably used as "the irradiation of short-wavelength light such as an electron beam or an EUV (extrareme ultraviolet) laser or an ultraviolet ray, a polymer. The main chain is cut and the molecular weight is reduced.

(positive photoresist composition)

The positive resist composition of the present invention (hereinafter also referred to simply as "photoresist composition") contains a polymer and a solvent, and further contains a known additive which is optionally blended with the photoresist composition. Further, since the positive-type resist composition of the present invention contains a polymer to be described later, if it is pre-baked under the conditions described later, the adhesion can be improved, and the molecular weight of the polymer can be suppressed from decreasing.

In addition, the solid content concentration of the positive resist composition is preferably 1% by mass or more, preferably 2% by mass or more, more preferably 20% by mass or less, and preferably 15% by mass or less.

<polymer>

The polymer is an α-alkylstyrene-α-chloroacrylate copolymer containing an α-alkylstyrene unit and an α-chloroacrylate unit as a monomer unit (repeating unit). Further, the proportion of the α-alkylstyrene unit in the polymer is not particularly limited, and may be, for example, 30 mol% or more and 70 mol% or less. Further, the ratio of the α-chloroacrylate unit in the polymer is not particularly limited, and may be, for example, 30 mol% or more and 70 mol% or less. Further, the polymer may further contain any monomer unit other than the α-chloro acrylate unit and the α-alkyl styrene unit, but among all the monomer units constituting the polymer, the α-chloro acrylate unit and the α-alkane The proportion of the styrene units is preferably 90 mol% or more, and substantially 100 mol% is preferably 100 mol% (that is, the polymer contains only α-chloroacrylate units and α-alkanes. The styrene unit) is more preferred.

Further, since the polymer contains a structural unit (α-chloroacrylate unit) derived from an α-chloroacrylate having a chlorine group (-Cl) at the α-position, if it is irradiated with an illuminating radiation or the like (for example, an electron beam, KrF laser, ArF laser, EUV laser, etc.), the main chain is easily cut and low molecular weight.

"α-alkylstyrene unit"

The α-alkylstyrene unit contained in the polymer is derived from a structural unit of α-alkylstyrene. Examples of the α-alkylstyrene unit include a carbon number of 4 or less such as an α-methylstyrene unit, an α-ethylstyrene unit, an α-propylstyrene unit, and an α-butylstyrene unit. The linear alkyl group is bonded to the α-alkylstyrene unit of the α carbon. Among them, the α-alkylstyrene unit is preferably an α-methylstyrene unit from the viewpoint of improving dry etching resistance when a polymer is used as a positive photoresist.

Here, the copolymer may have only one type of the above-mentioned unit as the α-alkylstyrene unit, or may have two or more types.

"α-chloroacrylate unit"

The α-chloroacrylate unit contained in the polymer is derived from a structural unit of α-chloroacrylate. The α-chloroacrylate unit may, for example, be an α-chloroalkyl acrylate unit such as an α-chloro acrylate unit or an α-chloro acrylate unit. Among them, from the viewpoint of improving the sensitivity when using a copolymer as a positive resist, the α-chloroacrylate unit is preferably an α-chloromethyl acrylate unit.

Here, the copolymer may have only one type of the above-mentioned unit as the α-chloroacrylate unit, or may have two or more types.

"Properties of Polymers"

The properties of the polymer used in the method for forming a photoresist film of the present invention, that is, the ratio of the "component of the specified molecular weight" and the "weight average molecular weight (Mw)" of the polymer before heating in the pre-baking step, The "molecular weight distribution (Mw/Mn)" of the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) is explained.

Further, in the present invention, "weight average molecular weight (Mw)" and "number average molecular weight (Mn)" can be measured by gel permeation chromatography.

[Proportion of the components of the specified molecular weight]

- the proportion of components with a molecular weight of more than 70,000

The polymer having an α-alkylstyrene unit and an α-chloroacrylate unit has a ratio of a component having a molecular weight of more than 70,000, preferably 90% or more, and preferably 93% or more. When the ratio of the component having a molecular weight of more than 70,000 is 90% or more, the molecular weight of the photoresist film formed by heating the positive-type resist composition containing such a polymer in the pre-baking step can be suppressed. Further, the proportion of the component having a molecular weight of more than 70,000 in the polymer may also be 100%.

- the proportion of components with a molecular weight of more than 80,000

Further, the ratio of the polymer having a molecular weight of more than 80,000 is preferably 80% or more, and preferably 87% or more. When the ratio of the component having a molecular weight of more than 80,000 is 80% or more, the decrease in molecular weight when the photoresist film formed by using the positive-type photoresist composition containing such a polymer is heated and heated in the pre-baking step can be further effectively suppressed. Further, the proportion of the component having a molecular weight of more than 80,000 in the polymer may also be 100%.

Further, in the above polymer, the ratio of the component having a molecular weight exceeding a specified value may be a chromatogram obtained by gel permeation chromatography, and the total area of the peak of the component whose molecular weight in the chromatogram exceeds a specified value is calculated. (D) Determined from the ratio of the total area (A) of the peak in the chromatogram (= (D/A) × 100%).

[weight average molecular weight]

Further, the weight average molecular weight (Mw) of the polymer having an α-alkylstyrene unit and an α-chloroacrylate unit may be, for example, 10,000 or more and 3,000,000 or less, and more preferably 20,000 or more and 2,000,000 or less. More preferably, it is 30,000 or more and 1,000,000 or less, and more preferably 300,000 or more and 1,000,000 or less. When the weight average molecular weight (Mw) of the polymer is at most the above upper limit value, the coatability of the photoresist composition can be further improved. In addition, when the weight average molecular weight (Mw) of the polymer is at least the above lower limit value, it is possible to suppress the improvement of the solubility of the photoresist film to the developer with an excessively low irradiation amount, and it is possible to suppress the obtained photoresist pattern. The resolution is excessively degraded.

[The molecular weight distribution]

Further, the molecular weight distribution (Mw/Mn) of the polymer having an α-alkylstyrene unit and an α-chloroacrylate unit may be, for example, 2.50 or less. Further, the molecular weight distribution (Mw/Mn) of the polymer is preferably 1.20 or more, more preferably 1.30 or more, and most preferably 2.10 or less. When the molecular weight distribution (Mw/Mn) of the polymer is at least the above lower limit value, the ease of production of the polymer can be improved. When the molecular weight distribution (Mw/Mn) of the polymer is at most the above upper limit value, the resolution of the photoresist pattern obtained when used as a positive photoresist can be improved.

"Modulation Method of Polymer"

Further, the above polymer having an α-alkylstyrene unit and an α-chloroacrylate unit can be polymerized, for example, by polymerizing a monomer composition comprising an α-alkylstyrene unit and an α-chloroacrylate unit. Prepared by arbitrarily purifying the obtained crude polymer product.

Further, the composition, molecular weight distribution, weight average molecular weight, and number average molecular weight of the polymer can be adjusted by changing the polymerization conditions and purification conditions. Specifically, the composition of the polymer can be adjusted by changing the content ratio of each monomer in the monomer composition used for the polymerization. Further, if the polymerization temperature is increased, the weight average molecular weight and the number average molecular weight can be reduced. Further, if the polymerization time is shortened, the weight average molecular weight and the number average molecular weight can be reduced.

[Polymerization of monomer composition]

Here, as the monomer composition used in the preparation of the polymer of the present invention, a monomer component containing an α-alkylstyrene unit and an α-chloroacrylate unit, an optional solvent, a polymerization initiator, and the like can be used. A mixture of additives added arbitrarily. Moreover, the polymerization of the monomer composition can be carried out using a known method. Among them, a radical polymerization method as disclosed in, for example, International Patent Publication No. 99/62964 is preferred, and an emulsion polymerization method is preferred.

Further, the polymerized crude product obtained by polymerizing the monomer composition is not particularly limited, and a solution in which a good solvent has been added can be dropped into methanol by adding a good solvent such as tetrahydrofuran to a solution containing the polymerized crude product. The crude polymerization product is solidified and recovered in a poor solvent.

"Purification of Polymerization Crude Products"

Further, the purification method used in the purification of the obtained crude polymerization product is not particularly limited, and known purification methods such as a reprecipitation method or a column chromatography method may be mentioned. Among them, as the purification method, it is preferred to use a reprecipitation method.

Further, the purification of the crude polymerization product can be carried out repeatedly.

Further, the purification of the crude product by the reprecipitation method is carried out by, for example, dissolving the obtained crude polymer product in a good solvent such as tetrahydrofuran, and then dropping the obtained solution into a poor solvent such as methanol or tetrahydrofuran. It is preferred to carry out a mixture of a solvent and a poor solvent such as methanol to precipitate a part of the crude polymer. Among them, from the viewpoint of easily obtaining a product of a desired property, it is preferable to precipitate a mixed solvent of a good solvent and a poor solvent after being dissolved in a good solvent to precipitate a crude polymer product. When the solution of the crude product is dropped into a mixed solvent of a good solvent and a poor solvent to purify the crude product, the obtained polymerization can be easily adjusted by changing the kind or mixing ratio of the good solvent and the poor solvent. The molecular weight distribution, the weight average molecular weight and the number average molecular weight of the substance. Specifically, the more the ratio of the good solvent in the mixed solvent is increased, the more the molecular weight of the polymer precipitated in the mixed solvent can be increased.

Further, in the case where the crude polymer product is purified by the reprecipitation method, as the polymer, a polymerized crude product precipitated in a mixed solvent of a good solvent and a poor solvent may be used, and a precipitated product may be used without being precipitated in the mixed solvent. The crude product is polymerized (i.e., the polymerized crude product dissolved in the mixed solvent). Here, the crude polymerization product which is not precipitated in the mixed solvent can be recovered from the mixed solvent by a known method such as concentrated dry solidification.

Further, the recovered crude product may be washed by acidic water prepared using an acid such as hydrochloric acid or the purified crude product which has been arbitrarily purified after recovery. The pH of the acidic water is, for example, less than pH 6. Further, the method of cleaning by acidic water is not particularly limited, and the method disclosed in, for example, International Patent Publication No. 99/62964 can be followed.

Solvent

As the solvent, one selected from the group consisting of cyclopentanone (boiling point: 131 ° C, surface tension: 33.4 Mn/m), methyl 3-methoxypropionate (boiling point: 142 ° C, surface tension: 27.9 Mn/m) At least one solvent of a group of methyl crotonate (boiling point: 118 ° C, surface tension: 25.5 Mn/m). These may be used alone or in combination.

By using the above solvent, the coating property of the positive resist composition can be improved. Further, by using the above solvent, in the case where the above-mentioned polymer having an α-alkylstyrene unit and an α-chloroacrylate unit is used as a positive photoresist, the prebaking operation can be carried out at a lower temperature range. The formed photoresist film and the workpiece are in close contact with each other.

Among them, from the viewpoint of further improving the coatability of the photoresist composition, the solvent preferably contains methyl 3-methoxypropionate or cyclopentanone, and from the viewpoint of easy entry and versatility, the solvent is It is preferred to contain cyclopentanone. Further, as described above, the solvent may be a mixture, but from the viewpoint of easiness of recovery and reuse of the solvent, a single solvent composed of a single substance is preferred.

(Photoresist film forming method)

The method for forming a photoresist film according to the present invention is a method for forming a photoresist film for forming a photoresist film using the positive photoresist composition of the present invention, which comprises a coating process of applying a positive photoresist composition onto a workpiece. A pre-baking step of heating the coated positive-type photoresist composition with a temperature P (° C.) and a time t (minutes) satisfying the following formula (1).
-0.4P+52≦t・・・(1)

Further, in the formula (1), t>0.

<Coating process>

In the coating step, the positive resist composition is applied onto a workpiece such as a substrate processed by a resist pattern. The coating method is not particularly limited and can be carried out by a known coating method.

Further, the workpiece to which the positive resist composition is applied may be a substrate or a "blank mask" in which a light shielding layer is formed on the substrate.

<Pre-baking process>

In the pre-baking process, the coated positive-type photoresist composition (pre-bake) is heated to form a photoresist film.

Here, heating (prebaking) is performed by satisfying the temperature P (° C.) and the time t (minute) of the following formula (1). The range of the temperature P (°C) and the time t (minutes) satisfying the formula (1) is clearly shown in FIG. Fig. 1 is a graph showing the relationship between the temperature P (°C) and the time t (minutes) in the prebaking step in the method for forming a photoresist film using the positive resist composition of the present invention. Here, the temperature P (° C.) and the time t (minutes) satisfy the following formula (1), meaning that “in the graph of FIG. 1 , the temperature P (° C.) and the time t (minute) exist above the straight line X. region". Thereby, the coating property of the photoresist composition can be improved, and the adhesion between the photoresist film and the workpiece when the pre-baking process is performed in a lower temperature range can be improved.
-0.4P+52≦t・・・(1)

Further, it is preferable that the temperature P (° C.) and the time t (minutes) satisfy the following formula (2).
-0.25P+37≦t・・・(2)

If the above formula (2) is satisfied (in the graph of Fig. 1, the temperature P (°C) and the time t (minute) overlap the straight line Y or the right side of the straight line Y), the temperature P (°C) and the time t (minutes) When pre-baking (heating) is performed, it is possible to further balance the coating property of the photoresist composition while improving the adhesion between the photoresist film and the workpiece during the pre-baking step in a lower temperature range.

Further, from the viewpoint of the adhesion between the photoresist film formed by the prebaking step and the workpiece, the temperature P (° C.) is preferably 100° C. or higher, more preferably 110° C. or higher, and From the viewpoint of reducing the thermal influence on the workpiece and the photoresist film, it is preferably less than 170 ° C and preferably 150 ° C or less. From the viewpoint of further improving the adhesion between the photoresist film formed by performing the prebaking step in the lower temperature range and the workpiece, the time t (minutes) is preferably more than 1 minute, and more preferably 2 minutes or more. Preferably, it is more preferably 3 minutes or longer, and from the viewpoint of reducing the change in the molecular weight of the polymer in the photoresist film before and after the pre-baking step, it is preferably 30 minutes or shorter, more preferably 10 minutes or shorter.

Further, the maintenance ratio of the weight average molecular weight of the polymer heated by the pre-baking step (the weight average molecular weight of the polymer after heating in the pre-baking step / the weight average molecular weight of the polymer before heating in the pre-baking step) ), preferably 95.0% or more.

<Photoresist pattern forming method>

The photoresist pattern forming method preferably comprises (1) a step of forming a photoresist film by using the photoresist film forming method, (2) a step of exposing the photoresist film, and (3) a step of developing the exposed photoresist film. .

Exposure Process

In the above step (2), a desired pattern is drawn by irradiating the photoresist film with free radiation or light. Further, for the irradiation of the radiation or the light, a known drawing device such as an electron beam drawing device or a laser drawing device can be used.

Development Process

In the above step (3), the photoresist film on which the pattern is drawn is brought into contact with the developer to develop the photoresist film, and a photoresist pattern is formed on the workpiece. Here, the method of bringing the photoresist film into contact with the developer is not particularly limited, and a known method such as immersing the photoresist film in a developer or applying a developer to the photoresist film can be used. Then, the developed photoresist film is optionally rinsed with an eluent.

In particular, as the developer and the eluent, known ones can be used. As the developer and the eluent, for example, an acetate having a chain alkyl group such as amyl acetate, butyl acetate or hexyl acetate; a mixture of an alcohol and an acetate having an alkyl group can be used. The combination of the developer and the eluent takes into consideration the solubility of the photoresist formed by the above polymer, and for example, a solvent having a high photoresist solubility can be used as a developer to improve the photoresist solubility. The low solvent is defined as the eluent. Further, when the developer is selected, it is preferred to select a developer which does not dissolve the photoresist film before the step (2). Further, when the eluent is selected, it is preferable to select an eluent which is easily mixed with the developer to be replaced with the developer.

(Manufacturing method of stack)

The method for producing a stacked body of the present invention is a method for producing a stacked body comprising a substrate, a light shielding layer formed on the substrate, and a stack of photoresist films formed on the light shielding layer, which is formed by the photoresist film of the present invention. The method forms the aforementioned photoresist film.

<Substrate>

As the substrate, a transparent substrate is usually used. Examples of the material of the substrate include transparent materials such as quartz and glass. These may be used alone or in combination of two or more. Among these, quartz is preferred from the viewpoint of transparency and weather resistance.

The substrate preferably has a transparency of 90% to 95% of light having a wavelength of 200 nm or more and 300 nm or less.

The thickness of the substrate is preferably 0.5 mm or more, more preferably 1.0 or more, and most preferably 20 mm or less, and preferably 15 mm or less.

<shading layer>

As the light shielding layer, any light shielding layer can be used. Among them, as the light shielding layer, a light shielding layer having a single layer structure or a multilayer structure including a metal layer is preferably used. Further, examples of the material of the layer other than the metal layer constituting the light shielding layer include polypropylene, cyclic polyolefin, and polyvinyl chloride.

Examples of the material of the metal layer include chromium, ruthenium, iron oxide, and molybdenum molybdenum. These may be used alone or in combination of two or more. Among these, in terms of light blocking properties, chromium is preferred.

The thickness of the light shielding layer is preferably 5 nm or more, more preferably 10 nm or more, and most preferably 200 nm or less, and preferably 100 nm or less.

<Photoresist film>

The photoresist film is formed by the method of forming a photoresist film of the present invention. Thereby, the adhesion between the photoresist film and the light shielding layer can be improved.

The thickness of the photoresist film is preferably 20 nm or more, more preferably 30 nm or more, and preferably 200 nm or less, and preferably 100 nm or less.

『Example』

The invention will be specifically described below based on examples, but the invention is not limited to the examples. In addition, in the following description, unless otherwise stated, the “%” and “parts” of the quantity are the quality basis. In the following examples, "the ratio of the components of the specified molecular weight in the polymer", "the weight average molecular weight and the molecular weight distribution", and the "adhesion between the photoresist film formed by the pre-baking process and the workpiece", The "coating property of the positive photoresist solution" and the "maintenance ratio of the weight average molecular weight of the polymer in the photoresist film formed by the prebaking process" were measured and evaluated by the following methods.

<Proportion of the components of the specified molecular weight in the polymer>

A gel of a polymer was obtained by using a gel permeation chromatography (HLC-8220, manufactured by Tosoh Corporation) and using tetrahydrofuran as a developing solvent. Then, from the obtained chromatogram, the total area (A) of the peaks, the total area of the peaks of the components having a molecular weight of more than 70,000 (D ₇ ), and the total area of the peaks of the components having a molecular weight of more than 80,000 (D ₈ ) were obtained. Then, the ratio of the components of the respective molecular weights was calculated using the following formula.
Proportion (%) of components having a molecular weight of more than 70,000 = (D ₇ /A) × 100
Proportion (%) of the component having a molecular weight of more than 80,000 = (D ₈ /A) × 100

<weight average molecular weight and molecular weight distribution>

The weight average molecular weight (Mw) and the number average molecular weight (Mn) were measured by gel permeation chromatography for the polymer to be measured, and the molecular weight distribution (Mw/Mn) was calculated.

Specifically, a gel permeation chromatography (HLC-8220, manufactured by Tosoh Corporation) was used, and tetrahydrofuran was used as a developing solvent, and the weight average molecular weight of the polymer to be measured was determined by a standard polystyrene conversion value (Mw). And the number average molecular weight (Mn). Then, the molecular weight distribution (Mw/Mn) was calculated.

<Adhesion of the photoresist film formed by the pre-baking process to the workpiece>

The presence or absence of peeling of the formed photoresist pattern was observed, and the adhesion between the photoresist film and the workpiece was evaluated in accordance with the following criteria. The absence of peeling of the photoresist pattern means that the adhesion is good.
A: The photoresist pattern has no peeling
B: The photoresist pattern has peeling off

<Coating property of positive photoresist solution>

A positive-type photoresist solution having a polymer concentration of 4% by mass was filtered through a filter having a pore diameter of 0.45 μm ("DISMIC" manufactured by ADVANTEC Toyo Co., Ltd.) to obtain a filtrate. The obtained filtrate was applied onto a tantalum wafer having a diameter of 4 Å as a substrate using a spin coater ("MS-A150" manufactured by MIKASA Co., Ltd.). Further, the coating was carried out under conditions of 300 rpm for 3 seconds and 1800 rpm (at room temperature of 23 ° C) for 57 seconds. After coating, a photoresist film was formed by prebaking at 180 ° C for 3 minutes on a hot plate. Thereafter, the surface of the photoresist film formed on the germanium wafer was visually observed, and the coatability (coating property) of the positive photoresist solution was evaluated in accordance with the following criteria. The results are disclosed in Table 1. Further, at the time of the evaluation, a photoresist film was formed in the comparative example using anisole as a solvent, and the coating properties of the examples and the comparative examples were evaluated under the same conditions, and the temperature was relatively high at 180 ° C. The pre-baking process is carried out at a temperature. However, in the case where a specific solvent is used in each embodiment, except that the photoresist solution can be coated more favorably by spin coating, the prebaking process is carried out at a relatively low temperature range of, for example, less than 170 ° C. In the middle, it can also form a good film.

Evaluation Benchmark
A: can be coated, and the obtained coating film is free from defects
B: can be coated, and the obtained coating film has a small amount of defects tolerable
C: a large number of defects that are poorly coated or can be applied but the obtained coating film has an unacceptable degree

<Retention rate of weight average molecular weight of polymer in photoresist film formed by pre-baking process>

Calculating the ratio of the weight average molecular weight MW _B of the polymer in the photoresist film formed by the prebaking step when the weight average molecular weight MW _A of the polymer used for the preparation of the positive photoresist composition is 100% (=MW _B /MW _A ×100[%]). As a result, in all of the examples and comparative examples, the value of R calculated for the polymer to be used was 95% or more. From this, it is understood that the polymers A and B used in the examples and the comparative examples have almost no change in molecular weight even in the pre-baking step.

(Example 1, Experiment No. E1-1-1)

<Preparation of Polymer A>

2,750 parts of pure water and 3 parts of sodium carbonate, and 225 parts of a solution obtained by dissolving KS Soap (manufactured by Kao Corporation, semi-cured tallow fatty acid potassium soap) in ion-exchanged water at a solid concentration of 17.5% by mass, and placed in a separate flask. Dissolved. 450 parts of methyl α-chloroacrylate and 1084 parts of α-methylstyrene as a monomer were added, and the mixture was emulsified by vigorous stirring. After replacing the inside of the flask with nitrogen, 0.4 parts of sodium disulfame sulfinate, 0.15 parts of sodium iron diamine tetraacetate trihydrate, 0.375 parts of tetrasodium ethylenediaminetetraacetate tetrahydrate, sodium formaldehyde sulfoxylate were sequentially added. 0.225 parts and 0.786 parts of cumene hydroperoxide were subsequently stirred at 5 ° C for 48 hours. After the reaction was stopped by adding 7.5 parts of 2,6-di(tributyl)-4-cresol, 14,000 parts of methanol was dropped into the reaction liquid, and the precipitated solid component was filtered. The obtained solid component was dissolved in 8000 parts of tetrahydrofuran (THF), and the obtained solution was added dropwise to 14,000 parts of methanol, and the precipitated solid component was filtered off. Further, the obtained solid component was dissolved in 8000 parts of THF, and the obtained solution was dropped into 14,000 parts of methanol. The precipitated solid component was filtered off to obtain a solid component A. Then, the obtained solid component A was dried to obtain a polymer containing 750 parts of α-methylstyrene unit and α-chloromethyl acrylate unit. The polymer contained 47 mol% of α-methylstyrene units and 53 mol% of α-chloromethyl acrylate units.

Then, 750 parts of the obtained polymer was dissolved in 9000 parts of dichloromethane to obtain a solution. To the obtained solution, 9000 parts of a 0.005 N aqueous hydrochloric acid solution (pH: 2.3) was added and stirred to prepare a mixed solution. After the mixture was allowed to stand, the aqueous layer was removed by decantation.

The remaining methylene chloride layer was dropped into 14,000 parts of methanol, and the precipitated solid component was filtered off and dried to obtain 740 parts of a polymer containing an α-methylstyrene unit and an α-chloromethyl acrylate unit. A.

Then, for the polymer A to follow the above measurement results, the ratio of the components of the molecular weight specified in the polymer A, the ratio of the component having a molecular weight of more than 70,000 is 94.13 (%), and the ratio of the component having a molecular weight of more than 80,000 is 92.53. (%), weight average molecular weight was 342,123, and molecular weight distribution was 2.023.

<Preparation of Positive Photoresist Composition>

The obtained polymer A was dissolved in cyclopentanone as a solvent as described above to prepare a photoresist solution (positive photoresist composition) having a concentration of the polymer A of 2% by mass.

<Formation of photoresist pattern>

A positive photoresist composition was applied to a blank mask having a diameter of 4 Å using a spin coater (MS-A150 manufactured by MIKASA Co., Ltd.) (a chromium layer was formed on a quartz substrate (thickness: 1.0 mm) (thickness: 10 nm) ))). Subsequently, the coated positive resist composition was heated under the prebaking conditions (temperature P [° C.] and time t [minute]) shown in Table 1 (pre-baking process) to form a thickness on the blank mask. 50 nm photoresist film. Then, the weight average molecular weight (Mw) was calculated using gel permeation chromatography for the polymer in the obtained photoresist film. Following the above, the maintenance rate of the weight average molecular weight of the polymer was evaluated.

Further, an electron beam drawing device (ELS-S50, manufactured by ELIONIX Co., Ltd.) was used to expose the photoresist film at an optimum exposure amount (E _op ) to draw a pattern. Thereafter, a developing solution made of amyl acetate (ZED-N50, manufactured by Nippon Seon Co., Ltd.) was used as a developing solution for photoresist, and after development treatment at a temperature of 23 ° C for 1 minute, it was rinsed with isopropyl alcohol. In seconds, a photoresist pattern is formed. Then, the adhesion of the photoresist film formed by the prebaking step to the blank mask was evaluated as described above. Further, the optimum exposure amount (E _op ) is appropriately set. Also, the line width (unexposed area) and the line pitch (exposure area) of the photoresist pattern were set to 20 nm, respectively.

The evaluation results obtained are disclosed in Table 1.

(Example 1, Experiment No. E1-1-2)

Various operations were carried out in accordance with (Example 1, Experiment No. E1-1-1), except that the polymer B prepared as described below was used instead of the above polymer A as a polymer blended with the positive resist composition. Evaluation. The results are disclosed in Table 1.

<Preparation of Polymer B>

The solid component A obtained by following the procedure described in the "Preparation of Polymer A" was dissolved in 8000 parts of THF, and the obtained solution was added dropwise to 14000 parts of a mixed solvent of THF and methanol (MeOH) (THF: MeOH = 68.5: 31.5 (mass ratio)), and a coagulum (a polymer containing a specified property of an α-methylstyrene unit and an α-chloromethyl acrylate unit) was precipitated. Thereafter, the solution containing the coagulum was filtered through a Kiriyama funnel to obtain a solid component B. Then, after drying the obtained solid component B, it was dissolved in 9000 parts of dichloromethane to obtain a solution. To the obtained solution, 9000 parts of a 0.005 N aqueous hydrochloric acid solution (pH: 2.3) was added and stirred to prepare a mixed solution. After the mixture was allowed to stand, the aqueous layer was removed by decantation.

The remaining methylene chloride layer was dropped into 14,000 parts of methanol, and the precipitated solid component was filtered off and dried to obtain a polymer B containing an α-methylstyrene unit and an α-chloromethyl acrylate unit. Further, the polymer B contained 47 mol% of α-methylstyrene units and contained 53 mol% of α-chloroacrylic acid methyl ester units.

Then, as a result of the measurement of the polymer B as described above, the ratio of the component of the molecular weight specified in the polymer B, the ratio of the component having a molecular weight of more than 70,000, and the ratio of the component having a molecular weight of more than 80,000 are 100.00 (%), The weight average molecular weight was 432,795 and the molecular weight distribution was 1.438.

(Other Experimental Examples of Example 1 and Various Experimental Examples of Comparative Example 1)

The pre-baking conditions when the polymer blended in the preparation of the positive-type photoresist composition and the formation of the photoresist pattern were determined to follow the combination of Table 1, and the comparison was carried out (Example 1, Experiment No. E1). -1-1) Various operations and evaluations. The results are disclosed in Table 1.

(Example 2, Comparative Example 2)

In the preparation of the positive photoresist composition, methyl 3-methoxypropionate was used as a solvent. The pre-baking conditions when the polymer blended in the preparation of the positive-type photoresist composition and the formation of the photoresist pattern were set to follow the combination of Table 2, and the comparison was carried out (Example 1, Experiment No. E1) -1-1) Various operations and evaluations. The results are disclosed in Table 2.

(Example 3, Comparative Example 3)

In the preparation of the positive photoresist composition, methyl crotonate was used as a solvent. The pre-baking conditions when the polymer blended in the preparation of the positive photoresist composition and the formation of the photoresist pattern were determined to follow the combination of Table 3, and the comparison was carried out (Example 1, Experiment No. E1). -1-1) Various operations and evaluations. The results are disclosed in Table 3.

(Comparative Example 4)

In the preparation of the positive photoresist composition, anisole was used as a solvent. The pre-baking conditions when the polymer blended in the preparation of the positive-type photoresist composition and the formation of the photoresist pattern were set to follow the combination of Table 4, and the comparison was carried out (Example 1, Experiment No. E1) -1-1) Various operations and evaluations. The results are disclosed in Table 4.

(Example 5, Comparative Example 5)

The coating properties of the positive photoresist solution were evaluated in accordance with the above methods using the polymers A and B prepared in accordance with Example 1 and the respective solvents shown in Table 5. The results are disclosed in Table 5.

In Table 5, "Mw" represents a weight average molecular weight, and "Mw/Mn" represents a molecular weight distribution.

[Table 1]

[Table 2]

[table 3]

[Table 4]

[table 5]

As is clear from Table 5, "polymer A and polymer B having a ratio of a component having a molecular weight of more than 70,000 and having an α-alkylstyrene unit and an α-chloroacrylate unit and having a molecular weight of more than 70,000" and " A positive photoresist composition selected from the group consisting of cyclopentanone, methyl 3-methoxypropionate, and methyl crotonate has excellent coatability. On the other hand, as is clear from Table 5, when anisole was used as a solvent instead of the above specific solvent, the coating property of the obtained positive resist composition was poor.

Further, as is clear from Tables 1 to 3, according to the above-described positive-type photoresist composition, even when the pre-baking step is performed in a relatively low temperature range of less than 170 ° C, the obtained light can be enhanced. The adhesion between the resist film and the workpiece on which the photoresist film is formed.

Further, as is clear from each of Comparative Examples 4 shown in Table 4, in the case of using a positive resist composition not containing the above specific solvent, it is not possible to obtain a prebaking step in a relatively low temperature range of less than 170 °C. The adhesion between the formed photoresist film and the workpiece.

Further, according to each of the comparative examples shown in Tables 1 to 3, in the method of forming a photoresist film which does not satisfy the prebaking conditions (temperature P and time t) of the formula (1), it is not possible to obtain a prebaking step. The adhesion between the photoresist film and the workpiece.

The positive-type resist composition of the present invention is excellent in coatability, and the adhesion between the resist film and the workpiece can be improved even when the pre-baking step is performed in a relatively low temperature range.

Further, according to the method for forming a photoresist film of the present invention, the adhesion between the photoresist film formed by the prebaking step and the workpiece can be improved.

Further, according to the method for producing a stacked body of the present invention, the adhesion between the photoresist film formed by the prebaking step and the light shielding layer can be improved.

no.

Fig. 1 is a graph showing the relationship between the temperature P (°C) and the time t (minutes) in the prebaking step in the method for forming a photoresist film using the positive resist composition of the present invention.

Claims (5)

A positive photoresist composition comprising a positive photoresist composition of a polymer and a solvent, wherein the polymer comprises an α-chloroacrylate unit and an α-alkylstyrene unit, and a molecular weight of more than 70,000 The ratio is 90% or more, and the solvent contains at least one selected from the group consisting of cyclopentanone, methyl 3-methoxypropionate, and methyl crotonate. The positive-type resist composition according to claim 1, wherein a ratio of a component having a molecular weight of more than 80,000 of the polymer is 80% or more. A method for forming a photoresist film, which is a method for forming a photoresist film using a positive photoresist composition according to claim 1 or 2, comprising: coating the positive photoresist composition on a coating step on the workpiece, and a pre-baking step of heating the coated positive-type photoresist composition, wherein the pre-baking step is performed at a temperature P (° C.) and a time t (minute) satisfying the following formula (1) In the heating, -0.4P+52≦t・・・(1). The method of forming a photoresist film according to claim 3, wherein the time t is more than 1 minute and less than 30 minutes. A method of manufacturing a stacked body, which is a method of manufacturing a stack comprising a substrate, a light shielding layer formed on the substrate, and a stack of photoresist films formed on the light shielding layer, wherein The photoresist film forming method described in 4 forms the photoresist film.