JP6420975B2 - Resist sensitivity evaluation method, transfer mask manufacturing method, imprint mold manufacturing method, and resist-attached substrate supply method - Google Patents

Description

  The present invention relates to a resist sensitivity evaluation method, a transfer mask manufacturing method, an imprint mold manufacturing method, a resist-coated substrate supply method, and a resist-coated substrate.

In recent years, with the progress of microstructuring of semiconductor devices, demands for the dimensional accuracy of resist patterns on mask blanks have become increasingly severe. It is necessary to form an auxiliary pattern such as SRAF (Sub-Resolution Assist Feature) having a line width of 40 nm or less, which is often formed in a transfer pattern corresponding to the generation of DRAM half pitch 32 nm or later. In addition, the SRAF pattern is required to have a high level of dimensional accuracy. Specifically, CDU (Critical Dimension Uniformity), which is an index of in-plane uniformity of the resist pattern, is required to be 5 nm or less, preferably 3 nm or less.
Similarly, in the technique related to the imprint mold for forming fine irregularities by a photolithography method, requirements for dimensional accuracy are becoming strict.
In order to meet such demands, it is necessary to appropriately evaluate the in-plane distribution of resist sensitivity of the resist layer that is the basis of the resist pattern.

  With regard to the resist sensitivity of the resist layer on the mask blank, for example, it is proposed to develop the resist layer and evaluate the quality of the in-plane distribution of the resulting resist pattern dimensions (for example, patents). Reference 1). In addition, for example, it has been proposed to evaluate the sensitivity of the resist layer based on the amount of reflected light by irradiating the resist layer with ultraviolet light (see, for example, Patent Document 2).

JP 2005-326581 A JP 2009-271473 A

However, the conventional resist sensitivity evaluation methods have the following problems.
For example, since the method disclosed in Patent Document 1 requires that the resist layer be subjected to development processing, the resist layer is a destructive inspection. Therefore, patterning or the like cannot be performed on the resist layer after inspection, and it cannot be said that the sensitivity evaluation on the resist layer can be performed appropriately.
Further, for example, the method disclosed in Patent Document 2 needs to irradiate the resist layer with ultraviolet light. For example, when the entire surface of the resist layer is set as an irradiation target region of ultraviolet light, the type of the resist material Depending on the situation, the pattern formation region of the resist layer may be adversely affected, and a sampling inspection must be performed on some mask blanks. In addition, when an area other than the pattern formation area is an irradiation target area of the ultraviolet light, the in-plane distribution of resist sensitivity in the pattern formation area cannot be grasped. That is, in either case, it cannot be said that sensitivity evaluation for the resist layer can be performed appropriately.

  Therefore, the present invention provides a resist sensitivity evaluation method capable of appropriately evaluating the in-plane distribution of resist sensitivity in the resist layer, a transfer mask manufacturing method, an imprint mold manufacturing method, and a resist-coated substrate supply method. And it aims at providing the base material with a resist.

The variation in resist sensitivity may be due to the thermal history given to the resist layer or the uneven distribution of the resist composition generated during the application of the resist material, although the difference in the film thickness of the resist layer is one factor. . In particular, the uneven distribution of the resist composition may cause a large variation in resist sensitivity because, for example, a molecular weight distribution of the main polymer occurs. In consideration of this, it is considered that the fluctuation of the resist sensitivity in the resist layer can be evaluated by grasping the uneven distribution of the resist composition constituting the resist layer.
The resist composition is mainly composed of a photosensitive resin, a photoacid generator (PAG), a basic compound, a surfactant, and an organic solvent as a solvent. Such a resist composition is applied on a substrate as a resist material to form a resist coating film, and then subjected to a heat treatment called pre-exposure baking (pre-baking) performed on the resist coating film, and the resist layer is formed. Will form. At this time, the solvent as the resist composition is removed by heat treatment. Therefore, if uneven distribution occurs in other resist compositions excluding the solvent, the uneven distribution becomes obvious by the heat treatment. In other words, when the resist coating film is subjected to heat treatment to form a resist layer, the resist film thickness is reduced by the heat treatment, but if the resist composition is unevenly distributed, the uneven distribution is caused by the heat treatment. Since it becomes apparent, the resist thinning rate varies depending on the uneven distribution.
This is considered to mean that there is a correlation between the fluctuation of the resist thinning rate in the plane of obtaining the resist layer and the fluctuation of the resist sensitivity in the plane of the resist layer. The existence of such a correlation is a new finding obtained from the results of intensive studies by the present inventors.
This invention is made | formed based on the novel knowledge by this inventor mentioned above.

<Configuration 1>
The first configuration of the present invention includes a step of forming a resist coating film on a surface of a substrate, a step of measuring a film thickness of the resist coating film and creating a first film thickness map, and the resist coating A step of heat-treating the film to form a resist layer, a step of measuring the film thickness of the resist layer to create a second film thickness map, the first film thickness map and the second film thickness map And a step of creating a resist film thickness reduction map before and after the heat treatment using the method, and a step of evaluating a resist sensitivity distribution of the resist layer based on the resist film thickness reduction map. This is a sensitivity evaluation method.

<Configuration 2>
The second configuration of the present invention is a method for manufacturing a transfer mask, comprising a step of forming a resist coating film on a thin film side surface of a mask blank having a thin film, and measuring a film thickness of the resist coating film. A step of creating a first film thickness map; a step of heat-treating the resist coating film to form a resist layer; a step of measuring a film thickness of the resist layer and creating a second film thickness map; A step of creating a resist film reduction rate map before and after heat treatment using the first film thickness map and the second film thickness map, and based on the resist film reduction rate map or the resist film reduction rate map And a step of performing pattern exposure on the resist layer by determining an exposure intensity using a resist sensitivity distribution map of the resist layer to be created.

<Configuration 3>
According to a third configuration of the present invention, in the method for manufacturing a transfer mask according to the second configuration, the method includes a step of applying a resist material to the surface on the thin film side, and in the step of forming the resist coating film, The material is roughly dried to form the resist coating film.

<Configuration 4>
A fourth configuration of the present invention is a method for manufacturing an imprint mold, the step of forming a resist coating film on the surface of an imprint mold blank, and measuring the film thickness of the resist coating film. A step of creating one film thickness map, a step of heat-treating the resist coating film to form a resist layer, a step of measuring a film thickness of the resist layer and creating a second film thickness map, Creating a resist film reduction rate map before and after the heat treatment using the first film thickness map and the second film thickness map, and creating based on the resist film reduction rate map or the resist film reduction rate map A step of determining an exposure intensity using a resist sensitivity distribution map of the resist layer and performing pattern exposure on the resist layer. It is a production method.

<Configuration 5>
According to a fifth configuration of the present invention, in the method for manufacturing an imprint mold according to the fourth configuration, the method includes a step of applying a resist material on the surface, and in the step of forming the resist coating film, the resist The material is roughly dried to form the resist coating film.

<Configuration 6>
According to a sixth configuration of the present invention, the resist-coated substrate is obtained by forming a resist coating film on the surface of the substrate and then heating the resist coating film to obtain a resist layer. A method for supplying a substrate with a resist used when supplying a first film thickness map obtained by measuring a film thickness of the resist coating film, and measuring a film thickness of the resist layer. And a resist film thickness ratio map before and after the heat treatment is created, and the resist sensitivity of the resist layer created based on the resist film thickness ratio map or the resist film thickness ratio map At least one of the distribution maps is supplied with being attached to the resist-attached base material.

<Configuration 7>
The seventh configuration of the present invention is a resist-coated substrate obtained by forming a resist coating film on the surface of the substrate and then heat-treating the resist coating film to form a resist layer, wherein the resist coating Resist reduction before and after heat treatment was created using a first film thickness map obtained by measuring the film thickness and a second film thickness map obtained by measuring the film thickness of the resist layer. At least one of a film rate map or a resist sensitivity distribution map of the resist layer created based on the resist film reduction rate map is attached.

  According to the present invention, the in-plane distribution of resist sensitivity in the resist layer can be appropriately evaluated.

It is a schematic diagram which shows the structural example of the mask blank with a resist in embodiment of this invention. It is a flowchart which shows an example of the evaluation procedure of the resist sensitivity in embodiment of this invention. It is explanatory drawing which shows a specific example of a resist film reduction rate map. It is explanatory drawing which shows a specific example of the measurement result of a resist sensitivity.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the present embodiment, description will be made by dividing into items in the following order.
1. Transfer mask 1. 2. Mask blank with resist 3. Resist sensitivity evaluation method 4. Mask blank supply method with resist 5. Transfer mask manufacturing method Effects of the present embodiment 7. Modifications etc.

<1. Transfer mask>
First, the transfer mask will be briefly described.
The transfer mask described in this embodiment is used for forming a fine pattern on a semiconductor substrate in a semiconductor device manufacturing process, for example.

  As a transfer mask, for example, a binary mask having a light shielding region and a transmission region for transmitting light (semiconductor exposure light) by a light shielding film pattern, and adjusting the light transmittance of the light shielding region in the binary mask so that the pattern is not transferred And a halftone phase shift mask that reverses the phase and a Levenson phase shift mask that performs phase control in the transmission region of the transfer mask.

  The binary mask, the halftone type phase shift mask, and the Levenson type phase shift mask are all manufactured using a mask blank. As will be described in detail later, the mask blank has a thin film for forming a light-shielding region (or a light semi-transmissive region in the case of a halftone phase shift mask) on a base material made of a translucent substrate. Become. Further, a resist layer is formed on the thin film of the mask blank, and this resist layer is used when a light shielding film and a phase shift film are patterned to form a light shielding area and a transmission area.

  Another example of the transfer mask is an EUV (Extreme Ultraviolet) mask used in extreme ultraviolet lithography. The EUV mask is configured to have a multilayer reflective film and an absorber pattern composed of a light absorbing film on the surface of low thermal expansion glass, an absorption region that absorbs exposure light by the absorber pattern, and a multilayer reflective film. And an exposed reflective area. Such an EUV mask is also manufactured using a mask blank. The resist layer in the mask blank is used when the light absorption film is patterned to form the absorption region and the reflection region.

<2. Mask blank with resist>
Next, a mask blank used for manufacturing a transfer mask will be described.
FIG. 1 is a schematic diagram illustrating a configuration example of a mask blank with resist in the present embodiment.

  The mask blank 1 shown in the figure is configured by forming a thin film 3 on one surface of a substrate 2. A resist layer 4 is formed on the surface of the mask blank 1 on the thin film 3 side. In the present embodiment, a mask blank 1 is a substrate in which a thin film 3 is formed on a substrate 2, and a mask with a resist is a substrate in which a resist layer 4 is formed and is composed of the substrate 2, the thin film 3 and the resist layer 4. It is called blank 5.

If the base material 2 is used for a light transmission type transfer mask, a glass substrate which is a light transmitting substrate is used. Specifically, the base material 2 used in any of the binary mask, the halftone type phase shift mask, and the Levenson type phase shift mask is selected to have a high light transmittance with respect to the exposure light when using the mask. Therefore, for example, when an ArF excimer laser (wavelength 193 nm) is applied as exposure light, synthetic quartz glass is used. In addition, soda lime glass, soda lime glass, or the like may be used depending on the application.
Moreover, the base material 2 does not require the light transmittance with respect to the exposure light at the time of mask use, when it is used for a light reflection type transfer mask. However, since EUV exposure light has high energy such as a wavelength of 13.5 nm, it is considered that the temperature of the substrate 2 is increased by the energy. Therefore, as the base material 2, low expansion glass is used because the pattern may be displaced due to the influence of thermal expansion. Specifically, as the low expansion glass _include SiO 2 -TiO ₂ type glass.

If the thin film 3 is used for a light transmission type transfer mask, a light-shielding metal film is used. Specific examples of the metal film will be described later.
Further, when the thin film 3 is used for a light reflection type transfer mask, a light absorbing metal film is used. Specific examples of the metal film will be described later.

  It is conceivable that the resist layer 4 is formed using a chemically amplified resist material for electron beam drawing in both cases of a light transmission type transfer mask and a light reflection type transfer mask. However, it is not necessarily limited to this, and other resist materials may be used as long as pattern formation can be performed through drawing and development by exposure. The resist layer 4 may be a positive type or a negative type.

  Specific examples of the mask blank 1 having such a configuration include those described in the following (a) to (e).

(A) Binary mask blank provided with a light shielding film made of a material containing a transition metal The binary mask blank has a thin film functioning as a light shielding film on a base material made of a translucent substrate. This light shielding film is made of a material containing a transition metal alone such as chromium, tantalum, ruthenium, tungsten, titanium, hafnium, molybdenum, nickel, vanadium, zirconium, niobium, palladium, rhodium, or a compound thereof. For example, a light-shielding film composed of chromium or a chromium compound in which one or more elements selected from elements such as oxygen, nitrogen, and carbon are added to chromium. Further, for example, a light shielding film composed of a tantalum compound in which one or more elements selected from elements such as oxygen, nitrogen, and boron are added to tantalum.
Such binary mask blanks include a light shielding film having a two-layer structure of a light shielding layer and a front surface antireflection layer, or a three-layer structure in which a back surface antireflection layer is added between the light shielding layer and the substrate.
Moreover, it is good also as a composition gradient film | membrane from which the composition in the film thickness direction of a light shielding film differs continuously or in steps.

(B) Phase shift mask blank provided with a light semi-transmissive film made of a material containing a compound of transition metal and silicon (including transition metal silicide, particularly molybdenum silicide) As such a phase shift mask blank, a light-transmitting substrate (glass A mask blank for a halftone type phase shift mask having a thin film functioning as a light semi-transmissive film on a base material made of a substrate, and having a shifter portion by patterning the light semi-transmissive film Is mentioned. In such a phase shift mask, in order to prevent a pattern defect of the transferred substrate due to the light semi-transmissive film pattern formed in the transfer region based on the light transmitted through the light semi-transmissive film, the light semi-transmissive is formed on the light-transmissive substrate. It is preferable to have a form having a film and a light shielding film (light shielding band) thereon. In addition to halftone phase shift mask blanks, mask blanks for Levenson type phase shift masks and enhancer type phase shift masks, which are substrate digging types in which a translucent substrate is dug by etching or the like to provide a shifter portion. Is mentioned.

  The light semi-transmissive film in such a halftone phase shift mask blank transmits light having a strength that does not substantially contribute to exposure (for example, 1% to 30% with respect to the exposure wavelength). Phase difference (for example, 180 degrees). The light semi-transmissive portion is transmitted through the light semi-transmissive portion by a light semi-transmissive portion patterned with the light semi-transmissive film and a light transmissive portion that does not have the light semi-transmissive film and transmits light having an intensity substantially contributing to exposure. By making the phase of the light a substantially inverted relationship with respect to the phase of the light transmitted through the light transmission part, the light passes through the vicinity of the boundary between the light semi-transmission part and the light transmission part, and is caused by a diffraction phenomenon. The light that has entered the area of the other party cancels each other, the light intensity at the boundary is made substantially zero, and the contrast (ie, resolution) of the boundary is improved.

The light semi-transmissive film is made of, for example, a material containing a compound of transition metal and silicon (including transition metal silicide), and examples thereof include a material mainly composed of these transition metal and silicon and oxygen and / or nitrogen. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium, or the like is applicable.
In the case of a form having a light-shielding film on the light semi-transmissive film, the material of the light semi-transmissive film contains a transition metal and silicon, so that the material of the light-shielded film has etching selectivity with respect to the light semi-transmissive film. In particular, it is preferably composed of chromium (having etching resistance) or a chromium compound in which elements such as oxygen, nitrogen, and carbon are added to chromium.

  Since the Levenson type phase shift mask is manufactured from a mask blank having the same configuration as the binary mask blank, the configuration of the pattern forming thin film is the same as that of the light shielding film of the binary mask blank. The light semi-transmissive film of the mask blank for the enhancer-type phase shift mask transmits light having an intensity that does not substantially contribute to exposure (for example, 1% to 30% with respect to the exposure wavelength). This is a film having a small phase difference generated in the exposure light (for example, a phase difference of 30 degrees or less, preferably 0 degrees), and this is different from the light semi-transmissive film of the halftone phase shift mask blank. The material of this light semi-transmissive film includes the same elements as the light semi-transmissive film of the halftone type phase shift mask blank, but the composition ratio and film thickness of each element have a predetermined transmittance and predetermined ratio to the exposure light. The phase difference is adjusted to be small.

(C) Binary mask blank provided with a light shielding film made of a material containing a compound of transition metal, transition metal and silicon (including transition metal silicide, particularly molybdenum silicide) The light shielding film is a material containing a compound of transition metal and silicon And a material mainly composed of these transition metals and silicon, and oxygen and / or nitrogen. Examples of the light-shielding film include a material mainly composed of transition metals and oxygen, nitrogen, and / or boron. As the transition metal, molybdenum, tantalum, tungsten, titanium, hafnium, nickel, vanadium, zirconium, niobium, palladium, ruthenium, rhodium, chromium, or the like is applicable.
In particular, when the light shielding film is formed of a molybdenum silicide compound, it has a two-layer structure of a light shielding layer (MoSi, etc.) and a surface antireflection layer (MoSiON, etc.), and further antireflection on the back surface between the light shielding layer and the substrate. There is a three-layer structure to which layers (MoSiON etc.) are added.
Moreover, it is good also as a composition gradient film | membrane from which the composition in the film thickness direction of a light shielding film differs continuously or in steps.

  In order to form a fine pattern by reducing the thickness of the resist film, an etching mask film may be provided over the light shielding film. This etching mask film has etching selectivity (etching resistance) with respect to etching of the light-shielding film containing transition metal silicide, and in particular, chromium, or a chromium compound in which elements such as oxygen, nitrogen, and carbon are added to chromium. It is preferable to use a material. At this time, by providing the etching mask film with an antireflection function, the transfer mask may be manufactured with the etching mask film remaining on the light shielding film.

(D) Multi-tone mask blank having a laminated structure of at least one semi-transmissive film and a light-shielding film The material of the semi-transmissive film is the same element as the light semi-transmissive film of the halftone phase shift mask blank described above. In addition, a material containing a simple metal such as chromium, tantalum, titanium, aluminum, an alloy, or a compound thereof is also included. The composition ratio and film thickness of each element are adjusted so as to have a predetermined transmittance with respect to the exposure light. As the material of the light shielding film, the light shielding film of the binary mask blank described above can be applied. However, the composition of the light shielding film material and the light shielding film material so that a predetermined light shielding performance (optical density) is obtained in a laminated structure with the semi-transmissive film. The film thickness is adjusted.

  In the above (a) to (d), the light-shielding film or the light semi-transmissive film is interposed between the light-transmitting substrate (glass substrate) and the light-shielding film or between the light semi-transmissive film and the light-shielding film. An etching stopper film having etching resistance may be provided. The etching stopper film may be a material that can peel off the etching mask film at the same time when the etching stopper film is etched.

(E) A reflective mask blank including an absorber film on a multilayer reflective film in which high refractive index layers and low refractive index layers are alternately stacked. The reflective mask is a mask used in EUV lithography. The reflective mask has a structure in which a multilayer reflective film that reflects exposure light is formed on a substrate, and an absorber film that absorbs exposure light is formed in a pattern on the multilayer reflective film. Light (EUV light) incident on a reflective mask mounted on an exposure machine (pattern transfer device) is absorbed by a portion having an absorber film and reflected by a multilayer reflective film in a portion having no absorber film. Is transferred onto the semiconductor substrate via the reflection optical system.

  The multilayer reflective film is formed by alternately laminating high refractive index layers and low refractive index layers. Examples of the multilayer reflective film include Mo / Si periodic multilayer films, Ru / Si periodic multilayer films, Mo / Be periodic multilayer films, and Mo compound / Si compound periodic multilayer films in which Mo films and Si films are alternately stacked for about 40 periods. Si / Nb periodic multilayer film, Si / Mo / Ru periodic multilayer film, Si / Mo / Ru / Mo periodic multilayer film, Si / Ru / Mo / Ru periodic multilayer film, and the like. The material can be appropriately selected depending on the exposure wavelength.

  The absorber film has a function of absorbing, for example, EUV light that is exposure light. For example, tantalum (Ta) alone or a material containing Ta as a main component can be preferably used. Such an absorber film preferably has an amorphous or microcrystalline structure in terms of smoothness and flatness.

  As a material containing Ta as a main component, a material containing Ta and B, a material containing Ta and N, a material containing Ta and B and further containing at least one of O and N, a material containing Ta and Si, Ta Material containing Si and N, Material containing Ta and Ge, Material containing Ta, Ge and N, Material containing Ta and Hf, Material containing Ta, Hf and N, Material containing Ta and Zr, Ta and Zr A material containing N and N can be used. By adding B, Si, Ge or the like to Ta, an amorphous material can be easily obtained and the smoothness can be improved. Further, if N or O is added to Ta, the resistance to oxidation is improved, so that the effect of improving the stability over time can be obtained.

<3. Resist sensitivity evaluation method>
Next, the procedure for evaluating the resist sensitivity of the resist layer 4 in the mask blank 5 with resist will be described. Here, the resist sensitivity evaluation procedure including the procedure for forming the resist layer 4 will be described.
FIG. 2 is a flowchart showing an example of a resist sensitivity evaluation procedure in the present embodiment.

(Coating process: S11)
In order to evaluate the resist sensitivity in the resist layer 4, it is necessary to form the resist layer 4 to be evaluated. Therefore, in the coating step (S11), on the upper surface of one surface of the base material 2, more specifically, on the thin film side surface of the mask blank 1 configured with the thin film 3 on the surface of the base material 2, A resist material that is a material for forming the resist layer 4 is applied.

  The resist material is composed of a plurality of types of resist compositions. Examples of the resist composition mainly include a photosensitive resin, a photoacid generator (PAG), a basic compound, a surfactant, and an organic solvent as a solvent. Of these resist compositions, at least the photosensitive resin is dispersed in a colloidal form in the solvent.

  Examples of a method for applying a resist material made of such a resist composition on the surface of the mask blank 1 include a spin coating method. The spin coating method is excellent in film thickness uniformity when a resist material is applied. However, in the spin coating method, when the resist material is developed on the surface of the mask blank 1, a centrifugal force acts on the resist composition constituting the resist material, and even if the film thickness is apparently excellent, It is conceivable that each resist composition is biased so as to be centrifuged.

(Rough drying step: S12)
After completion of the coating step (S11), the resist material applied on the surface of the mask blank 1 is then roughly dried as a rough drying step (S12). As a result, a resist coating film is formed on the surface of the mask blank 1.

(First measurement step: S13)
After the rough drying step (S12) is performed and the resist coating film is formed, as a first measurement step (S13), the film thickness of the formed resist coating film is measured to create a first film thickness map. .

  The thickness of the resist coating film is measured over the entire area of the resist coating film. However, a plurality of locations in the entire surface may be extracted, and the film thickness may be measured for the extracted points. Any film thickness measurement method may be used as long as it is non-destructive and non-contact, and a known method such as a spectral interference method, an eddy current phase displacement sensitive method, an electromagnetic induction method, or a fluorescent X-ray method may be used. .

  The first film thickness map represents the film thickness measurement results for the entire in-plane region of the resist coating film on a two-dimensional coordinate plane corresponding to the in-plane surface.

(Heat treatment process: S14)
After the first film thickness map is created in the first measurement step (S13), the pre-exposure bake (pre-bake) is then applied to the resist coating film on the surface of the mask blank 1 as the heat treatment step (S14). A heat treatment called is performed. The temperature and time of the heat treatment may be determined in advance according to the type of resist material on which the resist coating film is based. By undergoing such heat treatment (pre-baking), the resist layer 4 is formed on the surface of the mask blank 1.

  At this time, the solvent as the resist composition constituting the resist coating film is removed by heat treatment. Therefore, if uneven distribution occurs in other resist compositions excluding the solvent, the uneven distribution becomes obvious by the heat treatment. That is, when the resist coating film is heat-treated to form the resist layer 4, the resist film thickness is reduced by the heat treatment, but when the resist composition is unevenly distributed, the uneven distribution is the heat treatment. Thus, the resist thinning rate varies depending on the uneven distribution.

(Second measurement step: S15)
After the heat treatment step (S14) is performed and the resist layer 4 is formed, thereafter, as the second measurement step (S15), the film thickness of the formed resist layer 4 is measured to create a second film thickness map. .

  The film thickness measurement of the resist layer 4 is performed for the entire in-plane region of the resist layer 4 as in the case of the first measurement step (S13) described above. However, a plurality of locations in the entire surface may be extracted, and the film thickness may be measured for the extracted points. The extraction location in that case corresponds to the extraction location in the first measurement step (S13). The film thickness measurement method may be any non-destructive and non-contact method, and a known method such as a spectral interference method, an eddy current phase displacement sensitive method, an electromagnetic induction method, or a fluorescent X-ray method may be used. Conceivable.

  The second film thickness map represents the film thickness measurement results for the entire in-plane region of the resist layer 4 on a two-dimensional coordinate plane corresponding to the in-plane.

(Map creation process: S16)
When the second film thickness map is created in the second measurement step (S15), the film thickness measurement results before and after the heat treatment are aligned together with the first film thickness map obtained in the first measurement step (S13). Become. Therefore, after the second measurement step (S15), as the map creation step (S16), a resist film thickness reduction map before and after the heat treatment is created using the first film thickness map and the second film thickness map. To do.

  The resist film reduction rate map represents the calculation result of the resist film reduction rate for the entire in-plane region of the resist layer 4 on a two-dimensional coordinate plane corresponding to the in-plane. The resist film reduction rate is obtained by calculating the film thickness reduction amount of the resist layer 4 after the heat treatment relative to the film thickness of the resist coating film before the heat treatment as a ratio with respect to the film thickness of the resist coating film.

(Evaluation process: S17)
After the resist film reduction rate map is created in the map creating step (S16), the evaluation step (S17) is performed as necessary (for example, at the time before performing exposure for patterning the resist layer 4). In the evaluation step (S17), the resist sensitivity distribution of the resist layer 4 is evaluated based on the resist film reduction rate map.

  The resist sensitivity distribution can be evaluated as described below.

  After the completion of the map creation step (S16), a resist film reduction rate map for the resist layer 4 to be evaluated is obtained. The resist film reduction rate map represents the resist film reduction rate for the entire in-plane region of the resist layer 4 on a two-dimensional coordinate plane. Therefore, according to the resist film reduction rate map, the distribution state of the variation of the resist film reduction rate in the plane of the resist layer 4 is grasped. The fluctuation of the resist thinning rate can be considered as the uneven distribution of the resist composition that forms the basis of the resist layer 4 is manifested by the heat treatment. The uneven distribution of the resist composition can be a major factor in fluctuations in resist sensitivity. Considering these facts, it can be said that there is a correlation between the change in the resist thinning rate and the change in the resist sensitivity.

  It is considered that the relationship between the variation in the resist thinning rate and the variation in the resist sensitivity depends on the type of resist material. In other words, when the type of resist material is specified, the correlation between the resist thinning rate and the resist sensitivity can be specified accordingly, and as a result, the resist sensitivity is uniquely estimated from the resist thinning rate. It becomes possible.

  Based on the above, in evaluating the resist sensitivity distribution, the resist film reduction rate at each location in the plane of the resist layer 4 is recognized based on the resist film reduction rate map. Based on the correlation between the resist film reduction rate specified by the type of resist material and the resist sensitivity, the resist sensitivity at each location can be uniquely estimated from the resist film reduction rate at each location on the resist film reduction rate map. Then, the in-plane resist sensitivity of the resist layer 4 is evaluated by comparing the result of the estimation with a preset reference sensitivity or allowable sensitivity range.

  By passing through the procedure demonstrated above, the resist sensitivity of the resist layer 4 in the mask blank 5 with a resist will be evaluated.

<4. Mask blank supply method with resist>
Next, a method for supplying the mask blank with resist 5 will be described. The supply method described in the present embodiment is a method used when supplying the resist mask blank 5 from the manufacturer side of the resist mask blank 5 to the user side. The resist-equipped mask blank 5 to be supplied is obtained by forming a resist coating film on the surface of the substrate 2 and then heat-treating the resist coating film to form a resist layer 4. The surface of the substrate 2 here includes the surface when the thin film 3 is interposed, that is, the surface of the mask blank 1 on the thin film 3 side. Accordingly, the mask blank with resist 5 corresponds to a specific example of “a substrate with resist” in the present invention.

  In supplying such a mask blank 5 with a resist, the first film thickness map and the resist layer 4 in the mask blank 5 with a resist are obtained in the same manner as in “3. Resist sensitivity evaluation method” described above. A resist film thickness reduction map before and after the heat treatment is created using the second film thickness map. In addition to the resist thinning rate map, if necessary, a resist sensitivity distribution map of the resist layer 4 created based on the resist thinning rate map is created. This resist sensitivity distribution map is created uniquely from the contents of the resist film reduction rate map, and the resist sensitivity distribution state for the entire in-plane region of the resist layer 4 is displayed on a two-dimensional coordinate plane corresponding to the in-plane surface. It is represented by.

  When supplying the mask blank 5 with resist, at least one of the resist film thickness reduction map for the resist layer 4 of the mask blank 5 with resist or the resist sensitivity distribution map of the resist layer is used as the mask blank 5 with resist. Attached to and supplied. That is, at least one of the resist film thickness reduction map or the resist sensitivity distribution map of the resist layer is attached to the mask blank 5 with resist supplied to the user side.

  If the mask blank 5 with resist is supplied in this way, the user side to which the mask blank 5 with resist is supplied can refer to the attached resist film thickness reduction map or the resist sensitivity distribution map of the resist layer. The resist sensitivity distribution of the resist layer 4 in the mask blank with resist 5 can be evaluated in the same manner as in the case of “3. Resist sensitivity evaluation method” described above.

<5. Transfer Mask Manufacturing Method>
Next, a method for manufacturing a transfer mask using the mask blank 5 with resist will be described.

  When the transfer mask to be manufactured is a binary mask, a halftone phase shift mask, or a Levenson type phase shift mask, the resist layer 4 in the resist mask blank 5 is formed by patterning a light shielding film, a phase shift film, or the like. Used to form a light shielding region and a transmission region. When the transfer mask to be manufactured is an EUV mask, it is used for patterning the light absorption film to form an absorption region and a reflection region. In any case, the resist layer 4 is rendered as a resist pattern by pattern drawing by electron beam exposure and further development.

  At this time, for the resist pattern, for example, CDU is 5 nm or less, preferably 3 nm or less, and strict accuracy is required for dimensional accuracy. In order to meet such a requirement, it is necessary to appropriately evaluate the in-plane distribution of resist sensitivity of the resist layer 4.

  Regarding this point, according to the transfer mask manufacturing method of the present embodiment, the resist film reduction rate map is created for the resist layer 4 of the mask blank 5 with resist. Using the resist sensitivity distribution map of the resist layer 4 created based on the rate map, the in-plane distribution of the resist sensitivity of the resist layer 4 can be appropriately evaluated. Therefore, it is possible to meet strict requirements for the dimensional accuracy of the resist pattern.

  Specifically, when the resist layer 4 is patterned into a resist pattern, the in-plane distribution of the resist sensitivity of the resist layer 4 is grasped by using the resist thinning rate map or the resist sensitivity distribution map of the resist layer 4. After that, the exposure intensity for each location in the plane of the resist layer 4 is determined. Then, pattern exposure is performed on the resist layer 4 with the determined exposure intensity. If it does in this way, the pattern exposure with respect to each said location can be performed with the exposure intensity according to the resist sensitivity in each location in the surface of the resist layer 4. FIG. Therefore, it is possible to form a resist pattern with a dimensional accuracy that satisfies the strict requirement even when the CDU is 5 nm or less, preferably 3 nm or less, for example.

<6. Effects of this embodiment>
According to this embodiment, the following effects can be obtained.

In the present embodiment, heating is performed using a first film thickness map obtained by measuring the film thickness of the resist coating film and a second film thickness map obtained by measuring the film thickness of the resist layer 4. A resist film reduction rate map before and after the processing is created, and the resist sensitivity distribution in the resist layer 4 is evaluated based on the resist film reduction rate map. That is, in the present embodiment, the resist before and after the heat treatment (pre-baking) on the resist layer 4 based on the novel knowledge by the inventors of the present application that there is a correlation between the resist thinning rate in the resist layer 4 and the resist sensitivity. After grasping the film reduction rate, the resist sensitivity is estimated from the resist film reduction rate, and the resist sensitivity in the plane of the resist layer 4 is evaluated.
Therefore, according to the present embodiment, it is not necessary to develop the resist layer 4 or irradiate it with ultraviolet light, and the resist sensitivity of the resist layer 4 can be evaluated. Moreover, since it is only necessary to grasp the resist film reduction rate based on the film thickness measurement result, the sensitivity evaluation can be performed on the entire in-plane region (including the pattern formation region) of the resist layer 4. That is, according to this embodiment, the in-plane distribution of resist sensitivity in the resist layer 4 can be evaluated appropriately and in a short time.

Further, in the present embodiment, the in-plane distribution of resist sensitivity of the resist layer 4 is grasped by using a resist film thickness reduction map for the resist layer 4 or a resist sensitivity distribution map created from the resist film thickness reduction map. After that, the exposure intensity for each location in the plane of the resist layer 4 is determined. Then, pattern exposure is performed on the resist layer 4 with the determined exposure intensity to form a resist pattern, and a transfer mask is manufactured using the resist pattern. That is, the resist pattern can be formed under conditions that take into account the evaluation result after appropriately evaluating the in-plane distribution of resist sensitivity in the resist layer 4.
Therefore, according to the present embodiment, it is possible to form a resist pattern with a dimensional accuracy that satisfies the strict requirement even if the CDU is 5 nm or less, preferably 3 nm or less, as a result. It is possible to suitably cope with the progress of microstructuring.

  In particular, as described in the present embodiment, when the resist layer 4 is formed through the coating process (S11) for coating the resist material on the thin film side surface of the mask blank 1, the resist material is applied by spin coating. If it is carried out, uneven distribution tends to occur in the resist composition constituting the resist material. Even in such a case, as described in the present embodiment, if the resist sensitivity in the plane of the resist layer 4 is evaluated using the resist thinning rate before and after the heat treatment for the resist layer 4, the evaluation result This reflects the uneven distribution of the resist composition. That is, according to the present embodiment, even when the resist layer 4 is formed under conditions where uneven distribution of the resist composition can occur, the in-plane distribution of resist sensitivity in the resist layer 4 can be appropriately evaluated. it can.

In the present embodiment, when supplying the mask blank 5 with resist, at least one of the resist film thickness reduction map or the resist sensitivity distribution map of the resist layer for the resist layer 4 of the resist mask blank 5 is obtained. Attached to the mask blank 5 with resist is supplied. That is, at least one of the resist film reduction rate map or the resist sensitivity distribution map of the resist layer is attached to the supplied mask blank 5 with resist.
Therefore, according to this embodiment, on the user side to which the mask blank 5 with resist is supplied, the mask blank with resist is referred to by referring to the attached resist film thickness reduction map or the resist sensitivity distribution map of the resist layer. The in-plane distribution of resist sensitivity in the resist layer 4 can be appropriately evaluated. In other words, it is very convenient for the user side, and by appropriately evaluating the in-plane distribution of resist sensitivity in the resist layer 4 using the attached resist film reduction rate map or the like, the resist pattern Thus, it is possible to suitably cope with higher accuracy of semiconductor devices and finer structures of semiconductor devices.

<7. Modified example>
While embodiments of the present invention have been described above, the above disclosure is intended to illustrate exemplary embodiments of the present invention. That is, the technical scope of the present invention is not limited to the above exemplary embodiment.

  For example, in the above-described embodiment, the case where the present invention is applied to resist evaluation of the mask blank 5 with a resist used for manufacturing a transfer mask is taken as an example, but the present invention is not limited to this. The present invention can also be applied to resist evaluation of an imprint mold blank with resist used for manufacturing an imprint mold.

  The imprint mold is a pattern that is directly pressed against a resist film applied on a transfer object to perform pattern transfer. Therefore, the shape and dimensional accuracy of the fine pattern formed on the surface of the imprint mold greatly influence the shape and dimensional accuracy of the transferred pattern.

  Such an imprint mold is manufactured using an imprint mold blank. The imprint mold blank is configured by forming a chromium-based thin film, a tantalum-based thin film, or the like on the surface of a base material such as synthetic quartz glass as necessary, and further forming a resist layer on the surface. Then, the imprint mold blank is formed by patterning the resist layer on the imprint mold blank with a resist layer by lithography, and etching the thin film and substrate below using the resist pattern as a mask. Will be.

  For the resist evaluation of the imprint mold blank with a resist layer as described above, the in-plane distribution of resist sensitivity in the resist layer is appropriately evaluated by applying the present invention in exactly the same manner as in the above-described embodiment. I can do it. In that case, the imprint mold blank with a resist layer corresponds to a specific example of the “substrate with resist” in the present invention.

  In the above-described embodiment, the resist sensitivity in the plane of the resist layer 4 is evaluated using the resist film reduction rate before and after the heat treatment for the resist layer 4. Here, “after the heat treatment” is assumed to be the time when the heat treatment is finished and the resist layer 4 is formed, that is, the latest timing from the end of the heat treatment. However, the present invention is not necessarily limited to this, and the resist film thickness reduction rate may be obtained by measuring the film thickness at a timing after the elapse of a predetermined time from the end of the heat treatment. For example, when the resist sensitivity varies with time, it is possible to perform an evaluation reflecting the temporal variation of resist sensitivity by setting the timing after the elapse of a predetermined time from the end of the heat treatment. become. It is also possible to measure the film thickness at multiple timings after the heat treatment to determine the resist film reduction rate. In this case, the temporal change in resist sensitivity is determined from the resist film reduction rate at each timing. Will get.

  Here, the present invention will be described in detail by taking a mask blank for manufacturing a halftone type phase shift mask as an example. However, it is needless to say that the present invention is not limited to the following examples.

  In this example, the following mask blank was configured. A synthetic quartz glass substrate was used as the substrate. As the light semi-transmissive film as a thin film, a MoSiN film having a film thickness of 69 nm, a transmittance for light having a wavelength λ = 193 nm of 6.04%, and a phase difference of 179.5 ° was used. As the other light-shielding film, a laminated film of a chrome-lean CrOCN film having a thickness of 30 nm and a chromium-rich CrOCN film having a thickness of 14 nm was used. The optical density with respect to light having a wavelength of λ = 193 nm was set to 3.0 between the light semi-transmissive film and the light shielding film.

  The resist layer was formed as follows. First, as a pretreatment, the light shielding film was subjected to HMDS (adhesion improving coating agent) treatment under predetermined conditions. Then, a chemically amplified positive resist for electron beam drawing (PRL009: manufactured by Fuji Film Electronics Materials Co., Ltd.) is used as a resist material, and a spin coating method is adopted as a coating method so that a set film thickness becomes 120 nm. A resist coating film was formed, and the resist coating film was further heat-treated (prebaked) to form a resist layer.

With respect to the mask blank with resist thus obtained, a resist film thickness reduction map was created using the film thickness measurement results before and after the heat treatment.
FIG. 3 is an explanatory diagram showing a specific example of a resist film reduction rate map.
The resist film reduction rate map in the figure shows the resist film reduction rate in each divided area divided into a plurality of areas, and the resist film reduction ratio in each divided area is represented on the two-dimensional coordinate plane corresponding to the in-plane of the resist layer. It is. The numerical value displayed in each divided area is the value of the resist film reduction rate, and is calculated by using, for example, an arithmetic expression of (film thickness before and after heat treatment / film thickness before heat treatment) × 100. In addition, on the resist film reduction rate map, the display brightness of each divided region is made to correspond to the difference in the value of the resist film reduction rate.
According to such a resist thin film ratio map, the distribution state of the resist thin film ratio in the entire in-plane region of the resist layer can be easily grasped, and as a result, the resist sensitivity in the entire in-plane region of the resist layer is also unique. It is possible to infer.

In order to verify this, the resist sensitivity of the resist layer according to the resist film reduction rate map of FIG. 3 was actually measured.
FIG. 4 is an explanatory diagram showing a specific example of the measurement result of resist sensitivity.
The resist sensitivity measurement results shown in the figure are so-called CDU maps obtained by measuring the critical dimension (CD) of the entire area of the resist layer.

  When comparing the resist film reduction rate map of FIG. 3 and the CDU map of FIG. 4, it can be seen that the higher the resist film reduction rate in the resist film reduction rate map, the lower the sensitivity in the DOSE map. That is, it is recognized that there is a clear correlation between the resist film reduction rate in the plane of the resist layer and the resist sensitivity.

  DESCRIPTION OF SYMBOLS 1 ... Mask blank, 2 ... Base material, 3 ... Thin film, 4 ... Resist layer, 5 ... Mask blank with resist

Claims (12)

On the surface of the substrate, using a resist material containing a photosensitive resin, a photoacid generator, a basic compound, a surfactant and a solvent, and forming a resist coating film by spin coating ,
Measuring the film thickness of the resist coating film and creating a first film thickness map;
A step of heat-treating the resist coating film to form a resist layer;
Measuring the thickness of the resist layer to create a second thickness map; and
Divide the film thickness by the film thickness of the resist coating film, which is the difference between the film thickness of the resist coating film in the first film thickness map and the film thickness of the resist layer in the second film thickness map . Creating a resist film reduction rate map before and after heat treatment by calculating the film reduction rate;
Evaluating the resist sensitivity distribution of the resist layer based on the resist film reduction rate map;
A resist sensitivity evaluation method comprising: The resist sensitivity evaluation method according to claim 1, wherein the resist material is a chemically amplified resist material. The resist sensitivity evaluation method according to claim 1, wherein the heat treatment is a treatment for removing a solvent in the resist coating film. A method for manufacturing a transfer mask, comprising:
On the thin film side surface of the mask blank having a thin film , using a resist material containing a photosensitive resin, a photoacid generator, a basic compound, a surfactant and a solvent, and forming a resist coating film by spin coating ,
Measuring the film thickness of the resist coating film and creating a first film thickness map;
A step of heat-treating the resist coating film to form a resist layer;
Measuring the thickness of the resist layer to create a second thickness map; and
Divide the film thickness by the film thickness of the resist coating film, which is the difference between the film thickness of the resist coating film in the first film thickness map and the film thickness of the resist layer in the second film thickness map . a step of creating a resist down film rate map in the heat treatment before and after by calculating the film reduction rate,
Determining exposure intensity using a resist sensitivity distribution map of the resist layer created based on the resist film reduction rate map or the resist film reduction rate map, and performing pattern exposure on the resist layer;
A method for manufacturing a transfer mask, comprising: 5. The method for manufacturing a transfer mask according to claim 4, wherein the resist material is a chemically amplified resist material. 6. The method for manufacturing a transfer mask according to claim 4, wherein the heat treatment is a treatment for removing a solvent in the resist coating film. A method for manufacturing an imprint mold,
On the surface of the imprint mold blank, using a resist material containing a photosensitive resin, a photoacid generator, a basic compound, a surfactant and a solvent, and forming a resist coating film by a spin coating method ;
Measuring the film thickness of the resist coating film and creating a first film thickness map;
A step of heat-treating the resist coating film to form a resist layer;
Measuring the thickness of the resist layer to create a second thickness map; and
Divide the film thickness by the film thickness of the resist coating film, which is the difference between the film thickness of the resist coating film in the first film thickness map and the film thickness of the resist layer in the second film thickness map . Creating a resist film reduction rate map before and after heat treatment by calculating the film reduction rate;
Determining exposure intensity using a resist sensitivity distribution map of the resist layer created based on the resist film reduction rate map or the resist film reduction rate map, and performing pattern exposure on the resist layer;
A method for producing an imprint mold, comprising: The method for manufacturing an imprint mold according to claim 7, wherein the resist material is a chemically amplified resist material. The method for manufacturing an imprint mold according to claim 7 or 8, wherein the heat treatment is a treatment for removing a solvent in the resist coating film. On the surface of the substrate, a resist material containing a photosensitive resin, a photoacid generator, a basic compound, a surfactant and a solvent is used . After the resist coating film is formed by spin coating , the resist coating film is heated. For the resist-coated substrate obtained by making the resist layer, a method of supplying a resist-coated substrate used when supplying the resist-coated substrate,
Wherein in the resist and the film thickness of the resist coating film thickness of the coating film were measured in the first thickness map obtained by a second thickness map obtained by measuring the film thickness of the resist layer resist A resist film reduction rate map before and after the heat treatment is created by calculating a film reduction rate by dividing the film reduction amount that is a difference from the film thickness of the layer by the film thickness of the resist coating film. Supplying at least one of a resist sensitivity distribution map of the resist layer created based on a rate map or the resist film reduction rate map attached to the resist-attached substrate Method. The method for supplying a substrate with resist according to claim 10, wherein the resist material is a chemically amplified resist material. The method for supplying a substrate with resist according to claim 10 or 11, wherein the heat treatment is a treatment for removing a solvent in the resist coating film.