JP5410839B2 - Multi-tone photomask manufacturing method, multi-tone photomask, and pattern transfer method - Google Patents

Description

   The present invention relates to a multi-tone photomask used for manufacturing a semiconductor device such as an LSI or a liquid crystal display (hereinafter referred to as LCD), a method for manufacturing a multi-tone photomask, and a pattern transfer method. In particular, the present invention relates to a multi-tone photomask suitably used for manufacturing a thin-film transistor used for manufacturing a thin-film transistor liquid crystal display device, a multi-tone photomask manufacturing method, and a pattern transfer method.

  At present, for example, in the field of LCD, a thin film transistor liquid crystal display (hereinafter referred to as TFT-LCD) is easy to be thin and has low power consumption compared to a CRT (cathode ray tube). Commercialization is progressing rapidly. A TFT-LCD includes a TFT substrate having a structure in which TFTs are arranged in pixels arranged in a matrix, and a color filter in which red, green, and blue pixel patterns are arranged corresponding to each pixel. It has a schematic structure superimposed under the intervention of. A TFT-LCD has a large number of manufacturing steps, and conventionally, only a TFT substrate has been manufactured using 5 to 6 photomasks. Under such circumstances, in the manufacture of thin film transistors (TFTs) used in liquid crystal display devices, so-called multi-tone photomasks (multitone masks) are used in order to efficiently manufacture by reducing the number of masks used. It is known to use.

  This multi-tone photomask has a transfer pattern including a light-shielding portion, a light-transmitting portion, and a semi-light-transmitting portion on a transparent substrate, and when the pattern is transferred to a transfer object using the photomask. By controlling the amount of exposure light transmitted by the transfer pattern, a resist pattern having two or more different resist residual film values is formed on the resist film on the transfer target.

In Patent Document 1, for example, a thin film (semi-transparent film) containing metal and silicon and an inorganic etching mask layer (light-shielding film) such as chromium, which are resistant to mutual etching, are sequentially formed on a transparent substrate. In addition, a method for manufacturing a gray-tone mask in which a light-transmitting portion, a light-shielding portion, and a semi-light-transmitting portion are formed by patterning each film is described.
In Patent Document 2, for example, a light-shielding film pattern is formed on a transparent substrate, a semi-transparent film is formed on the entire surface of the substrate including the light-shielding film pattern, and then the semi-transparent film is patterned. Describes a method of manufacturing a gray-tone mask in which a light-transmitting portion, a light-shielding portion, and a semi-light-transmitting portion are formed.

JP 2007-256922 A JP 2006-268035 A

  The disadvantage of the graytone mask manufacturing method described in Patent Document 1 is that various types of masks having semi-transparent portions with various transmittances desired by users using this graytone mask are prepared. It is difficult to do. That is, normally, since a photomask blank in which a semi-transparent film and a light-shielding film are formed in advance on a transparent substrate is prepared as a stock so that the production can be started quickly, the semi-transparent film is determined in advance. The film has a predetermined film permeability. Therefore, in order to respond quickly to the needs of photomasks having semi-transparent portions with various transmittances desired by mask users, photomask blanks equipped with various types of semi-transparent films with different film thicknesses and compositions in advance. Must be prepared and in stock, which is very inefficient in production.

  On the other hand, in the gray-tone mask manufacturing method as described in Patent Document 2, a photomask blank in a state where a light-shielding film is formed on a transparent substrate, regardless of the types having different transmissivities of the semi-transparent portions. Is prepared, and when the specific transmittance desired by the user is determined, the film thickness and composition of the semi-translucent film can be determined and formed, compared with the manufacturing method of Patent Document 1. Is convenient. On the other hand, in the manufacturing process, the film forming process and the patterning process are alternately performed, and in the middle of the process, it is complicated to transport the mask and attach / detach the apparatus at the intermediate stage of manufacturing. There is an inconvenience that there are many opportunities for foreign matters to adhere.

  Therefore, for example, in the manufacturing method of Patent Document 1, a photomask blank in which a semi-transparent film having a larger film thickness is prepared in advance and the semi-transparent film is reduced by some means in the photolithography process. It is conceivable to form a film and adjust it to a desired transmittance. However, in this case, since the composition of the semi-transparent film is determined in advance, not only the transmittance but also the phase difference with respect to the exposure light of the semi-transparent film changes according to the change in the film thickness. For example, when a transfer pattern having a semi-transparent portion of a pattern portion having a relatively large line width (for example, about 3 to 10 μm) is to be transferred onto a transfer target, it is formed by a semi-transparent film on a photomask. If the phase difference between the semi-translucent part and the translucent part is too large, it will act as if there is a dark line due to phase inversion. Therefore, when the resist film on the transfer object is exposed using such a photomask, the exposure amount of the resist film different from the design at that portion is insufficient, and an unintended resist pattern shape defect occurs. . For example, in the TFT channel portion, the dark line portion may cause a disadvantage that the source and the drain are short-circuited. Therefore, if the thickness of the semi-translucent film is reduced in order to reduce the phase difference between the semi-translucent portion and the translucent portion, the transmittance increases. The remaining film value cannot be obtained.

On the other hand, when a transfer pattern having a semi-transparent portion of a pattern portion having a relatively small line width (for example, about 1 to 3 μm) is to be transferred onto a transfer target, an area close to the resolution limit of the exposure machine used Since exposure is performed, there is a need to make the cross-sectional shape of the resist pattern as vertical as possible by positively utilizing the phase difference between the semi-translucent portion and the translucent portion and improving the contrast by phase inversion.
In short, the conventional gray-tone mask (multi-tone photomask) has limitations in the selection of the transmissivity and phase of the semi-translucent portion, and it is difficult to adjust both to the desired values. It was difficult to obtain a desired resist pattern shape.

  The present invention has been made in view of the above-described conventional circumstances, and firstly, it is to provide a multi-tone photomask having a transmittance distribution of a desired semi-translucent portion according to a mask user's request. Objective. In addition, it is preferable to use the effective transmittance which considered also the diffraction phenomenon of the light which arises by the phase difference between a semi-translucent part and a translucent part for this transmittance | permeability. In addition, the present invention secondly provides such a multi-tone photomask with an efficient manufacturing process, reducing the possibility of adhesion of foreign substances, etc., and promptly responding to the needs of mask users. An object of the present invention is to provide a method for manufacturing a multi-tone photomask that can be used. A third object of the present invention is to provide a pattern transfer method using the multi-tone photomask.

In order to solve the above problems, the present invention has the following configuration.
(Configuration 1)
The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values, wherein the semi-translucent portion has a predetermined transmittance, and the semi-translucent portion and the translucent portion are mutually In the method of manufacturing a multi-tone photomask having a predetermined phase difference, a step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate, and at least by a photolithography method, By patterning each of the semi-transparent film and the light-shielding film, the transparent substrate surface or the translucent portion where the digging surface of the transparent substrate is exposed, the film of the semi-transparent film formed on the transparent substrate A patterning step of forming a semi-transparent portion from which a part of the semi-transparent portion is removed and a light-shielding portion in which the semi-transparent film and the light-shielding film are laminated, and the remaining film thickness of the semi-transparent film in the semi-transparent portion The predetermined transmittance is obtained, and the remaining film thickness of the semi-transparent film in the semi-translucent portion and the transparent substrate surface or the digging surface position of the translucent portion are A method for producing a multi-tone photomask, wherein a phase difference is obtained.

(Configuration 2)
In the patterning step, at the portion corresponding to the light transmitting portion and the semi-light transmitting portion, simultaneous etching with the same etchant is performed, so that at least the semi-light transmitting film is etched, and the light transmitting portion and the light transmitting portion The method for manufacturing a multi-tone photomask according to Configuration 1, wherein a semi-translucent portion is formed.
(Configuration 3)
The patterning step includes a first photolithography step performed by forming a resist pattern in a portion other than the light-transmitting portion and a second photolithography step performed by forming a resist pattern in a portion other than the semi-transparent portion. In the first photolithography process, the exposed light shielding film is removed and a part of the thickness of the semi-transparent film is removed. Production method.

(Configuration 4)
The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values, wherein the semi-translucent portion has a predetermined transmittance, and the semi-translucent portion and the translucent portion are mutually In the method of manufacturing a multi-tone photomask having a predetermined phase difference, a step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate, and at least by a photolithography method, By patterning the semi-transparent film and the light-shielding film, respectively, the translucent part where the digging surface of the transparent substrate is exposed, and the semi-transparent film at least partially remaining on the transparent substrate A patterning step of forming a light portion and a light-shielding portion in which the semi-transparent film and the light-shielding film are stacked, and the remaining transmittance of the semi-transparent film in the semi-transparent portion is obtained by the predetermined transmittance. And the remaining film thickness of the semi-transparent film in the semi-translucent part and the transparent substrate digging surface position of the translucent part are such that the predetermined phase difference is obtained. A method for manufacturing a multi-tone photomask.

(Configuration 5)
In the patterning step, the semi-transparent film and the transparent substrate are simultaneously etched by the same etchant in the portions corresponding to the translucent part and the semi-translucent part, thereby the translucent part. The method for manufacturing a multi-tone photomask according to Configuration 4, wherein the semi-translucent portion is formed.
(Configuration 6)
The patterning step includes a first photolithography step performed by forming a resist pattern in a portion other than the light-transmitting portion and a second photolithography step performed by forming a resist pattern in a portion other than the semi-transparent portion. In the first photolithography process, the exposed light-shielding film and the semi-transparent film are removed. In the second photolithography process, the exposed light-shielding film is removed, and then the simultaneous etching is performed, whereby the light-transmitting film is removed. A method for manufacturing a multi-tone photomask according to Configuration 4 or 5, wherein a portion and the semi-translucent portion are formed.

(Configuration 7)
In the first photolithography process, a part of the plate thickness of the exposed light shielding film, the semi-transparent film, and the transparent substrate is removed, and the plate thickness to be removed is determined based on the predetermined phase difference. The method for manufacturing a multi-tone photomask according to any one of Structures 4 to 6, wherein

(Configuration 8)
The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values, wherein the semi-translucent portion has a predetermined transmittance, and the semi-translucent portion and the translucent portion are mutually In the method of manufacturing a multi-tone photomask having a predetermined phase difference, a step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate, and at least by a photolithography method, By patterning the semi-transparent film and the light-shielding film, respectively, at least the translucent film on the transparent substrate surface or transparent substrate where the digging surface of the transparent substrate is exposed A patterning step of forming a semi-transparent portion having a part of the remaining film thickness, and a light-shielding portion in which the semi-transparent film and the light-shielding film are laminated, and in the patterning step, the translucent portion and the semi-transparent portion are formed. In the part corresponding to the light part, by performing simultaneous etching with the same etchant, at least the semi-transparent film is etched, and the translucent part and the semi-translucent part are formed, A method for manufacturing a multi-tone photomask.

(Configuration 9)
The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values, wherein the semi-translucent portion has a predetermined transmittance, and the semi-translucent portion and the translucent portion are mutually In a multi-tone photomask having a predetermined phase difference, a translucent part in which a digging surface of a transparent substrate is exposed, a semi-transparent part in which the semi-transparent film having a predetermined thickness is formed on the transparent substrate, and A semi-transparent film and a light-shielding part in which the light-shielding part is laminated, and the film thickness of the semi-transparent film in the semi-translucent part is such that the predetermined transmittance is obtained, and the semi-translucent film The film thickness of the semi-translucent film in the part and the transparent substrate digging surface position of the translucent part are Wherein the serial predetermined phase difference is formed so as to obtain, multi-tone photomasks.

(Configuration 10)
The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values, wherein the semi-translucent portion has a predetermined transmittance, and the semi-translucent portion and the translucent portion are mutually In a multi-tone photomask having a predetermined phase difference, a translucent part where a transparent substrate surface or a digging surface of the transparent substrate is exposed, and a semi-translucent film in which the semi-transparent film having a predetermined thickness is formed on the transparent substrate And a light-shielding portion in which the semi-light-transmitting film and the light-shielding film are laminated, and the light-transmitting portion and the semi-light-transmitting portion have a surface to be etched that is simultaneously etched by the same etchant. A multi-tone photomask characterized by the above.

(Configuration 11)
The multi-tone photomask according to Configuration 9 or 10, which is used for exposure light including a wavelength range from i-line (wavelength 365 nm) to g-line (wavelength 436 nm).
(Configuration 12)
The multi-tone photomask is a photomask for manufacturing a thin film transistor, the light shielding portion includes a portion corresponding to a source and a drain of the thin film transistor, and the translucent portion includes a portion corresponding to a channel of the thin film transistor. The multi-tone photomask according to any one of Configurations 9 to 11, wherein the multi-tone photomask is included.
(Configuration 13)
13. A pattern transfer method, wherein the multi-tone photomask according to any one of Structures 9 to 12 is used, and the transfer pattern is transferred onto a transfer target by an exposure machine.

  According to the present invention, the semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the translucent part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values on the resist film, wherein the semi-translucent portion has a predetermined transmittance, and the semi-transparent portion and A step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate in the method of manufacturing a multi-tone photomask in which the translucent part has a predetermined phase difference; By patterning at least the semi-transparent film and the light-shielding film by a photolithography method, the transparent substrate surface or the transparent substrate is formed on the transparent substrate where the digging surface of the transparent substrate is exposed. A patterning step of forming a semi-transparent part from which a part of the film thickness of the semi-translucent film is removed, and a light-shielding part in which the semi-transparent film and the light-shielding film are laminated, The remaining film thickness of the semi-transparent film is such that the predetermined transmittance is obtained, and the remaining film thickness of the semi-transparent film in the semi-transparent part and the surface of the transparent substrate or the digging of the translucent part By providing a manufacturing method of a multi-tone photomask, wherein a predetermined phase difference can be obtained, the insertion surface position has a desired transmittance according to the mask user's desire, and a desired A multi-tone photomask having a semi-transparent portion having a phase difference is obtained.

  Further, according to the present invention, the semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the translucent part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values on a resist film on a body, wherein the semi-translucent portion has a predetermined transmittance, and the semi-translucent portion And a step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate in a method for manufacturing a multi-tone photomask in which the part and the translucent part have a predetermined phase difference from each other Then, by patterning at least the semi-transparent film and the light-shielding film by photolithography, the translucent part where the digging surface of the transparent substrate is exposed and the semi-transparent film on the transparent substrate are reduced. A patterning step of forming a semi-transparent portion that remains at least partially and a light-shielding portion in which the semi-transparent film and the light-shielding film are laminated, and the remaining film thickness of the semi-transparent film in the semi-transparent portion is The predetermined transmittance can be obtained, and the remaining film thickness of the semi-translucent film in the semi-translucent portion and the transparent substrate digging surface position of the translucent portion have the predetermined phase difference. By providing a method for manufacturing a multi-tone photomask characterized in that a semi-transparent portion having a desired transmittance according to a mask user's request and a desired phase difference is provided. A gradation photomask is obtained.

Furthermore, according to the present invention, the above-described manufacturing method and the multi-tone photomask obtained thereby can precisely control the desired transmittance and phase difference, and the manufacturing process is efficient, and foreign matter and the like can be controlled. It is possible to reduce the possibility of adhesion and thus provide the mask user quickly according to the needs.
Furthermore, a desired transfer pattern shape desired by the mask user can be obtained satisfactorily by performing pattern transfer onto the transfer object using the multi-tone photomask.

It is sectional drawing for demonstrating the pattern transfer method using the multi-tone photomask of this invention. It is sectional drawing which shows 1st Embodiment of the manufacturing method of the multi-tone photomask by this invention. It is sectional drawing which shows 2nd Embodiment of the manufacturing method of the multi-tone photomask by this invention. It is sectional drawing which shows 3rd Embodiment of the manufacturing method of the multi-tone photomask by this invention. It is a figure which shows the relationship between the phase difference with the translucent part with respect to exposure light, and the effective transmittance | permeability distribution in the semi-transparent part of line | wire width of 2 micrometers and exposure light transmittance of 30%.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view for explaining a pattern transfer method using the multi-tone photomask of the present invention. A multi-tone photomask 20 of the present invention shown in FIG. 1 is used for manufacturing an electronic device such as a thin film transistor (TFT) of a liquid crystal display device (LCD), for example, and a transferred object 30 shown in FIG. On top, two or more resist patterns 33 having different film thicknesses are formed stepwise or continuously. In FIG. 1, reference numerals 32 </ b> A and 32 </ b> B denote films stacked on the substrate 31 in the transfer target 30.

  The multi-tone photomask 20 shows an example of a three-tone mask having one kind of semi-light-transmitting portion in addition to the light-shielding portion and the light-transmitting portion. Specifically, the use of the photomask 20 is shown. Occasionally shielding the exposure light (transmittance is approximately 0%), a light shielding part 11, a translucent part 12 transmitting the exposure light with the surface of the transparent substrate 1 exposed, and an exposure light transmittance of the translucent part of 100% Then, it is configured to have a transfer pattern including the semi-transparent portion 13 that reduces the transmittance to 20 to 80%, preferably about 20 to 60%. The light shielding part 11 is configured by providing a light semi-transmissive semi-transparent film 2 and a light-shielding light-shielding film 3 in this order on a transparent substrate 1 such as a glass substrate. The semi-transparent portion 13 is configured by forming the semi-transparent film 2 on the transparent substrate 1. In the multi-tone photomask 20 shown in FIG. 1, a part of the film thickness at the time of manufacturing the photomask blank is removed from the film thickness of the semitransparent film 2 constituting the semitransparent part 13. Therefore, the film has a predetermined transmittance with respect to exposure light (for example, i-line to g-line) and a predetermined phase difference with respect to the light-transmitting portion.

Examples of the semi-transmissive film 2 include a chromium compound, a molybdenum silicide compound, Si, W, and Al. Among these, chromium compounds include chromium oxide (CrOx), chromium nitride (CrNx), chromium oxynitride (CrOxN), chromium fluoride (CrFx), and those containing carbon and hydrogen. In addition to MoSix, MoSi nitride, oxide, oxynitride, carbide, etc. can be used as the molybdenum silicide compound. In the present invention, a film material containing a molybdenum silicide compound is particularly preferable. A film material containing a molybdenum silicide compound has an etching selectivity with a chromium-based material that is advantageously used for a light-shielding film, and in the manufacturing method described later, the other film with respect to an etching medium for etching one film. It is a material that is extremely superior in terms of etching. Note that the semi-transparent film may be stacked.
Furthermore, in the present invention, a material that can be etched by the same etchant as that of the transparent substrate is preferable as the material of the semi-translucent film. Therefore, molybdenum silicide or a compound thereof is particularly preferable. Thus, as will be described later, simultaneous etching can be performed in the semi-translucent portion and the portion corresponding to the translucent portion.

Examples of the material for the light shielding film 3 include Cr, Si, W, Al, Ta, and the like, or compounds thereof. A material mainly containing Cr is preferable. More preferably, by having a Cr-based compound layer such as Cr oxide or nitride as an antireflection layer on the surface, the accuracy of drawing a transfer pattern can be improved, and unnecessary reflection stray light when using a mask can be improved. Occurrence can be suppressed. The light shielding film preferably has a light shielding property with an optical density of 3.0 or more by itself or by lamination with a semi-transparent film.
When forming the light shielding film and the semi-transparent film on the transparent substrate, a known film forming method such as vacuum deposition or sputtering can be used.

  When the multi-tone photomask 20 as described above is used, the exposure light is not substantially transmitted through the light shielding unit 11, the exposure light is transmitted through the translucent unit 12, and the exposure light is transmitted through the semi-transparent unit 13. Therefore, the resist film (positive type photoresist film) formed on the transfer body 30 is thickened at a portion corresponding to the light shielding portion 11 when developed after transfer, and the semi-transparent portion 13 is formed. A resist pattern 33 is formed in which the film thickness is reduced at a portion corresponding to, and a remaining film is not substantially formed at a portion corresponding to the light transmitting portion 12 (see FIG. 1). In the case of using a negative photoresist, it is necessary to design in consideration that the resist film thickness corresponding to the light shielding portion and the light transmitting portion is reversed. The effect is sufficiently obtained.

  Then, first etching is performed on, for example, the films 32A and 32B of the transfer target 30 in the portion where the resist pattern 33 shown in FIG. 1 is not formed, and the thin portion of the resist pattern 33 is removed by ashing or the like. Then, the second etching is performed on, for example, the film 32 </ b> B in the transfer target 30. In this way, a process for two conventional photomasks is performed using one multi-tone photomask 20 (three-tone mask), and the number of necessary masks is reduced.

  In one embodiment of a multi-tone photomask according to the present invention, a translucent film and a light-shielding film formed on a transparent substrate are respectively patterned, and a transfer including the light-shielding part, the translucent part, and the semi-translucent part By providing a pattern, a multi-tone photomask for forming a resist pattern having two or more different resist residual film values on a resist film on a transfer object, wherein the translucent portion has a predetermined transmittance In the multi-tone photomask in which the translucent part and the translucent part have a predetermined phase difference from each other, the translucent part in which the digging surface of the transparent substrate is exposed, the transparent substrate having a predetermined film thickness A semi-transparent portion in which the semi-transparent film is formed, and a light-shielding portion in which the semi-transparent film and the light-shielding portion are laminated, and the film thickness of the semi-transparent film in the semi-transparent portion is the predetermined thickness A translucent film in the translucent part And the film thickness, surface position digging transparent substrate of the transparent portion is a multi-tone photomask, wherein said predetermined phase difference is formed so as to obtain. That is, the translucent part is formed by digging a predetermined amount of the transparent substrate, the semi-translucent part is formed having the semi-transparent film on the transparent substrate, and the light shielding part is The semi-transparent film and the light-shielding film are formed on the transparent substrate, and the predetermined phase difference is determined based on the film thickness of the semi-translucent film formed on the semi-translucent portion and the translucent film. The multi-tone photomask is formed by digging the transparent substrate in an optical part.

  In the multi-tone photomask shown in FIG. 1 described above, there is no digging of the transparent substrate 1 in the translucent part 12, and therefore, the phase difference with respect to the predetermined wavelength light between the semi-transparent part 13 and the translucent part 12 Is formed by the film thickness of the semi-transmissive film 2 formed in the semi-transmissive part 13. On the other hand, in the multi-tone photomask of the present embodiment, the translucent part is formed by digging a predetermined amount of a transparent substrate, and therefore, a predetermined wavelength between the semi-transparent part and the translucent part. The phase difference with respect to light is formed by the film thickness of the semi-transparent film formed in the semi-transparent part and the digging of the transparent substrate in the translucent part. Which form is selected depends on the material and film thickness of the semi-transparent film in the photomask blank used for manufacturing the mask, the transmittance of the semi-translucent part to be finally obtained, and the phase difference between the translucent part. Can be determined.

  The transmissivity of the semi-transparent part here refers to the exposure light when using the photomask, and can be the one when the translucent part is 100%. A predetermined wavelength light can be used as a representative wavelength of the exposure light. For example, the representative wavelength for evaluating the photomask may be i-line (wavelength 365 nm), h-line (wavelength 405 nm), or g-line (wavelength 436 nm). Alternatively, in many cases, the spectral characteristics of the exposure apparatus are not necessarily constant in each apparatus. For example, the exposure apparatus has exposure light in a wavelength range from i-line to g-line, and therefore has a wavelength range from i-line to g-line. The included wavelength light can also be set as the predetermined wavelength light.

The semi-transparent part has a predetermined transmittance with respect to the predetermined wavelength light. As this transmittance, the film transmittance due to the film thickness of the semi-transparent film formed in the semi-transparent part and the optical interference generated as a result of the light interference generated in the semi-transparent part due to the predetermined phase difference are combined. It can be a transmittance.
Also for the phase difference, a predetermined wavelength can be used as a representative wavelength for evaluating the photomask. For example, any of i-line (wavelength 365 nm), h-line (wavelength 405 nm), or g-line (wavelength 436 nm) is used. Preferably, for example, the predetermined phase difference can be set for a wavelength range extending from the i-line to the g-line.

  Here, the film transmittance of the semi-transparent film is a transmittance when the predetermined wavelength light is irradiated in a sufficiently large area with respect to the resolution of the exposure machine, and the transparent substrate before film formation This is the transmittance when the transmittance for light of a predetermined wavelength is 100%. The film transmittance of the semi-transparent film is a film transmittance obtained by selecting a predetermined film thickness in the material of the semi-transparent film.

In the multi-tone photomask of the present invention, the semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned, and provided with a transfer pattern including the light-shielding part, the translucent part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values on a resist film on a transfer target, wherein the semi-translucent portion has a predetermined transmittance, In the multi-tone photomask having a predetermined phase difference between the semi-transparent part and the translucent part, the transparent substrate surface or the transparent substrate surface where the digging surface of the transparent substrate is exposed, the transparent film having the predetermined thickness on the transparent substrate. A semi-transparent portion having a semi-transparent film, and a light-shielding portion in which the semi-transparent film and the light-shielding film are stacked, and the translucent portion and the semi-transparent portion are formed of the same etchant. Provide a surface to be etched with simultaneous etching Including multi-tone photomask characterized.
Such a photomask is an excellent multi-tone photomask that is efficiently manufactured with a low probability of occurrence of foreign matter and defects by a manufacturing method described later.

  In addition to the light-transmitting part and the light-shielding part as shown in FIG. 1 described above, not only a three-tone mask having one kind of semi-light-transmitting part, but also two semi-light-transmitting elements having different exposure light transmittances. The present invention is also suitably applied to a mask having four gradations having a portion or a mask having more gradations.

The photomask to which the present invention is preferably applied is a multi-tone photomask for manufacturing a TFT, the light shielding portion includes portions corresponding to the source and drain of the TFT, and the semi-transparent portion corresponds to the channel of the TFT. Part to be included.
In this case, the semi-translucent portion can have a pattern portion having a line width of 1 to 3 μm. When the pattern width is narrow, as in the channel portion of the TFT, it is close to the resolution limit of the exposure machine and is difficult to resolve, so there is an advantage of positively utilizing inversion due to the phase difference. The multi-tone photomask of the present invention, which can select the desired transmittance in the translucent part of the transfer pattern and the phase difference from the translucent part with a degree of freedom according to the desired pattern shape, is exactly suitable.

  Note that the optimum amount of the phase difference between the semi-transparent portion and the translucent portion with respect to light of a predetermined wavelength, for example, exposure light, varies depending on the transmissivity of the semi-transparent film and the line width of the pattern. For example, in the region where the transmittance is relatively low (transmittance of about 20 to 40%), 40 to 100 degrees is preferable in the vicinity of the line width of 1 to 3 μm, and 20 to 80 degrees is preferable in the case of the line width of 3 to 10 μm. In the case of a relatively high transmittance region (transmittance of 40 to 60%), it is preferable to set the angle to 40 to 80 degrees in the vicinity of the line width of 1 to 3 μm and 20 to 60 degrees in the case of the line width of 3 to 10 μm.

The multi-tone photomask according to the present invention as described above can be suitably manufactured by the multi-tone photomask manufacturing method of the present invention.
That is, according to the present invention, a semi-transparent film and a light-shielding film formed on a transparent substrate are respectively patterned and provided with a transfer pattern including a light-shielding part, a translucent part, and a semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values on the resist film, wherein the semi-translucent portion has a predetermined transmittance, and the semi-transparent portion and A step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate in the method of manufacturing a multi-tone photomask in which the translucent part has a predetermined phase difference; By patterning at least the semi-transparent film and the light-shielding film by photolithography, the transparent substrate surface or the transparent substrate is exposed on the transparent substrate, and the transparent substrate is exposed on the transparent substrate. A patterning step of forming a semi-transparent part from which a part of the film thickness of the semi-translucent film is removed, and a light-shielding part in which the semi-transparent film and the light-shielding film are laminated, and the semi-transparent part The remaining film thickness of the semi-transparent film is such that the predetermined transmittance is obtained, and the remaining film thickness of the semi-translucent film in the semi-translucent part and the transparent substrate surface of the translucent part or The digging surface position provides the method for manufacturing a multi-tone photomask, wherein the predetermined phase difference is obtained.
In addition, the present invention provides a translucent film and a light-shielding film formed on a transparent substrate, respectively, and includes a light-shielding part, a light-transmitting part, and a transfer pattern including the semi-light-transmitting part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values on the resist film, wherein the semi-translucent portion has a predetermined transmittance, and the semi-transparent portion and A step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate in the method of manufacturing a multi-tone photomask in which the translucent part has a predetermined phase difference; By patterning at least the semi-transparent film and the light-shielding film by photolithography, the translucent part where the digging surface of the transparent substrate is exposed, and the semi-transparent film on the transparent substrate are at least A patterning step of forming a partially remaining semi-transparent portion and a light-shielding portion in which the semi-transparent film and the light-shielding film are laminated, and the remaining film thickness of the semi-transparent film in the semi-transparent portion is A predetermined transmittance is obtained, and the remaining film thickness of the semi-transparent film in the semi-translucent portion and the transparent substrate digging surface position of the translucent portion can obtain the predetermined phase difference. A method for manufacturing a multi-tone photomask is also provided.

  Furthermore, the present invention provides a translucent film and a light-shielding film formed on a transparent substrate, respectively, and includes a light-shielding part, a light-transmitting part, and a transfer pattern including the semi-light-transmitting part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values on the resist film, wherein the semi-translucent portion has a predetermined transmittance, and the semi-transparent portion and A step of preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate in the method of manufacturing a multi-tone photomask in which the translucent part has a predetermined phase difference; By patterning at least the semi-transparent film and the light-shielding film by photolithography, the transparent substrate surface or the transparent substrate is exposed on the transparent substrate, and the semi-transparent film is exposed on the transparent substrate. A patterning step of forming a semi-transparent portion in which at least a part of the film thickness of the optical film remains, and a light-shielding portion in which the semi-transparent film and the light-shielding film are stacked. And a portion corresponding to the semi-translucent portion are subjected to simultaneous etching with the same etchant, so that at least the semi-transparent film is etched, and the translucent portion and the semi-transparent portion are formed. Also included is a method for manufacturing a featured multi-tone photomask.

Hereinafter, the manufacturing method of the multi-tone photomask of the present invention will be specifically described by dividing it into several embodiments.
[First Embodiment]
FIG. 2 is a cross-sectional view in the order of manufacturing steps showing a first embodiment of a method for manufacturing a multi-tone photomask according to the present invention.
In a photomask blank 10 used in the present embodiment, a translucent film 2 and a light shielding film 3 made of, for example, MoSix are formed on a transparent substrate 1 in this order. The light shielding film 3 has a laminated structure of a light shielding layer containing, for example, Cr as a main component and an antireflection layer containing Cr oxide or the like. The semi-transparent film 2 and the light-shielding film 3 are formed in this order, but other layers may be interposed. For example, a layer having an etching stopper function may be interposed between the semi-transparent film 2 and the light shielding film 3. Further, the semi-transparent film 2 may be a single layer or a laminated structure of a plurality of layers. The light-shielding film 3 preferably has a light-shielding property such that the optical density is 3.0 or more due to the light-shielding film alone or a laminated structure with the semi-transparent film 2.
In the photomask blank 10, a resist film 4 is formed on the light shielding film 3 by applying a resist (see FIG. 3A). A positive photoresist is used as the resist.

Next, a first photolithography process is performed. First, drawing is performed for the first time. Laser light or an electron beam can be used for drawing. By drawing a predetermined device pattern (for example, a drawing pattern for forming a resist pattern in a region corresponding to the light shielding portion and the semi-transparent portion) on the resist film 4, and performing development after drawing, A resist pattern 4a that defines a region corresponding to the light transmitting portion is formed (see FIG. 4B).
Next, dry or wet etching is performed on the light shielding film 3 on the transparent region exposed using the resist pattern 4a as a mask using a known etchant (see FIG. 4C). The MoSi semi-transparent film is resistant to the etching of the Cr-based light shielding film.
Subsequently, using the resist pattern 4a and the light-shielding film pattern as a mask, the semi-transparent film 2 on the exposed translucent region is dry or wet etched halfway using a known etchant (see FIG. 4D). That is, etching is performed for a time shorter than just etching that can completely remove the semi-transparent film, and a part of the film thickness of the semi-transparent film in the translucent part region is reduced. At this time, only the light shielding film pattern may be used as a mask. Thus, the film thickness of the semi-transparent film remaining in the translucent part region is finally reduced, and at the same time, the semi-transparent film in the translucent part region is removed. The film thickness is as follows. If the translucent film of the translucent part is completely removed at this time, the glass of the translucent part is dug when the semitranslucent part is finally etched, and the phase difference changes. Resulting in. For this reason, the film thickness of the semi-transparent film remaining in the translucent part at this stage is determined in consideration of the desired transmittance required for the translucent part and the phase difference with the translucent part in advance. It is preferable to keep it.
Here, the remaining resist pattern is removed (see FIG. 5E).

  Next, a second photolithography process is performed. The same resist film 5 as described above is formed on the entire surface of the substrate (see FIG. 5F), and a second drawing is performed. In the second drawing, a drawing pattern of the semi-translucent portion area is drawn. After drawing, development is performed to form a resist pattern 5a on the light-shielding portion other than the semi-light-transmissive portion and the region corresponding to the light-transmissive portion (see FIG. 5G). Thus, the boundary between the light shielding part region and the semi-transparent part region is defined.

Next, using the resist pattern 5a as a mask, the light shielding film 3 on the exposed semi-transparent part region is etched, and the semi-transparent film in the semi-transparent part region is exposed (see FIG. 11H). Then, the remaining resist pattern is removed (see (i) in the figure).
Next, using the etchant of the semi-transparent film, the semi-transparent film in the semi-transparent part region is reduced and the semi-transparent film remaining in the translucent part region is removed (FIG. (J )reference). That is, since the semi-transparent film and the transparent substrate have similar etching characteristics, for example, using the same fluorine-based etchant, the semi-transparent film and the translucent film at a position corresponding to the translucent part are used. Etch simultaneously.

  Thus, on the transparent substrate 1, the light-shielding part 11 made of a laminated film of the semi-transparent film 2 and the light-shielding film 3, the light-transmitting part 12 from which the transparent substrate 1 is exposed, and the semi-transparent film 2 made of the remaining film thickness. A multi-tone photomask (three-tone mask) 20 (same as the multi-tone photomask 20 in FIG. 1) on which a transfer pattern including the light transmitting portion 13 is formed is completed (see FIG. 1J).

In the multi-tone photomask 20, the film thickness (t ₀ ) of the semi-transparent film 2 constituting the semi-transparent portion 13 is smaller than the film thickness at the time of manufacturing the photomask blank. Therefore, the exposure light has a predetermined transmittance and a predetermined phase.
In addition, the obtained multi-tone photomask is provided with a surface to be etched, which is subjected to simultaneous etching with the same etchant, in the light-transmitting portion and the semi-light-transmitting portion as a result of adjusting the transmittance and the phase difference.

[Second Embodiment]
FIG. 3 is a cross-sectional view in the order of manufacturing steps showing a second embodiment of the method for manufacturing a multi-tone photomask according to the present invention.
Also in this embodiment, the same photomask blank 10 as that in the first embodiment is used (see FIG. 3A).

  Next, a first photolithography process is performed. First, drawing is performed for the first time. A predetermined device pattern (for example, a drawing pattern for forming a resist pattern in a region corresponding to the light-shielding portion and the semi-translucent portion) is drawn on the resist film 4, and development is performed after the drawing, thereby corresponding to the light-transmitting portion. A resist pattern 4a that defines a region is formed (see FIG. 4B).

Next, the light shielding film 3 on the light-transmitting region exposed using the resist pattern 4a as a mask is etched (see FIG. 5C).
Subsequently, using the resist pattern 4a and the light shielding film pattern as a mask, the semi-transparent film 2 on the exposed translucent region is etched (see FIG. 4D). In this embodiment mode, just etching is performed here to remove the semi-transparent film in the translucent region. At this time, only the light shielding film pattern may be used as a mask.
Here, the remaining resist pattern is removed (see FIG. 5E).

  Next, a second photolithography process is performed. The same resist film 5 as described above is formed on the entire surface of the substrate (see FIG. 5F), and a second drawing is performed. In the second drawing, a drawing pattern of the semi-translucent portion area is drawn. After drawing, development is performed to form a resist pattern 5a on the light-shielding portion other than the semi-light-transmissive portion and the region corresponding to the light-transmissive portion (see FIG. 5G). Thus, the boundary between the light shielding part region and the semi-transparent part region is defined.

Next, using the resist pattern 5a as a mask, the light shielding film 3 on the exposed semi-transparent part region is etched, and the semi-transparent film in the semi-transparent part region is exposed (see FIG. 11H). Then, the remaining resist pattern is removed (see (i) in the figure).
Next, using the etchant of the semi-transparent film, the semi-transparent film in the semi-transparent part region is reduced, and the transparent substrate 1 exposed in the translucent part region is etched and etched to increase the plate thickness. Decrease by a predetermined amount (see (j) in the figure).

  Thus, on the transparent substrate 1, the light-shielding portion 11 made of a laminated film of the semi-light-transmissive film 2 and the light-shielding film 3, the light-transmissive portion 12 where the digging surface of the transparent substrate 1 is exposed, and the semi-light-transmissive film 2. A multi-tone photomask (three-tone mask) 21 on which a transfer pattern including the light transmitting portion 13 is formed is completed (see (j) in the figure).

In the multi-tone photomask 21, the film thickness (t ₁ ) of the semi-transparent film 2 constituting the semi-transparent part 13 is smaller than the film thickness at the time of manufacturing the photomask blank. The plate thickness of the transparent substrate 1 in the translucent portion 12 region is reduced by d ₁ from the initial plate thickness by digging. As a result, the semi-transparent portion 13 region has a predetermined transmittance for the exposure light due to the film thickness (t ₁ ) of the remaining semi-transparent film, and digging (d ₁ ) and half of the transparent substrate in the translucent region. It has a predetermined phase difference depending on the thickness of the translucent film (t ₁ ) in the translucent part region.
The multi-tone photomask according to this embodiment has a larger phase difference between the semi-translucent portion and the translucent portion than in the first embodiment. Therefore, it can be applied when the line width of the semi-translucent portion is small and the contrast of the exposure light needs to be increased by the phase difference.

[Third Embodiment]
FIG. 4 is a sectional view in the order of manufacturing steps showing a third embodiment of the method for manufacturing a multi-tone photomask according to the present invention.
Also in the present embodiment, the same photomask blank 10 as that in the first embodiment is used (see FIG. 4A).

  Next, a first photolithography process is performed. First, drawing is performed for the first time. By drawing a predetermined device pattern (for example, a drawing pattern for forming a resist pattern in a region corresponding to the light shielding portion and the semi-transparent portion) on the resist film 4, and performing development after drawing, A resist pattern 4a that defines a region corresponding to the light transmitting portion is formed (see FIG. 4B).

Next, the light shielding film 3 on the light-transmitting region exposed using the resist pattern 4a as a mask is etched (see FIG. 5C).
Subsequently, using the resist pattern 4a and the light shielding film pattern as a mask, the semi-transparent film 2 on the exposed translucent region is etched (see FIG. 4D). Only the light shielding film pattern may be used as a mask. In this embodiment, overetching for a longer time than just etching is performed here to remove the semi-transparent film in the translucent part region, and the transparent substrate underneath is etched and etched to set the plate thickness to a predetermined value. Decrease.
Here, the remaining resist pattern is removed (see FIG. 5E).

  Next, a second photolithography process is performed. The same resist film 5 as described above is formed on the entire surface of the substrate (see FIG. 5F), and a second drawing is performed. In the second drawing, a drawing pattern of the semi-translucent portion area is drawn. After drawing, development is performed to form a resist pattern 5a on the light-shielding portion other than the semi-light-transmissive portion and the region corresponding to the light-transmissive portion (see FIG. 5G). Thus, the boundary between the light shielding part region and the semi-transparent part region is defined.

Next, using the resist pattern 5a as a mask, the light shielding film 3 on the exposed semi-transparent part region is etched, and the semi-transparent film in the semi-transparent part region is exposed (see FIG. 11H). Then, the remaining resist pattern is removed (see (i) in the figure).
Next, using the etchant of the semi-transparent film, the semi-transparent film in the semi-transparent part region is reduced, and the transparent substrate 1 exposed in the translucent part region is etched and etched to increase the plate thickness. It is further reduced from the step (d) (see (j) in the figure).

  Thus, on the transparent substrate 1, the light-shielding portion 11 made of a laminated film of the semi-transparent film 2 and the light-shielding film 3, the light-transmitting portion 12 from which the digging surface of the transparent substrate 1 is exposed, and the semi-transparent film having the remaining film thickness A multi-tone photomask (three-tone mask) 22 on which a transfer pattern including the semi-transparent portion 13 made of 2 is formed is completed (see (j) in the figure).

In the multi-tone photomask 22, the remaining film thickness (t ₂ ) of the semi-transparent film 2 constituting the semi-transparent portion 13 is reduced by a predetermined amount from the film thickness at the time of manufacturing the photomask blank. In addition, the thickness of the transparent substrate 1 in the region of the light transmitting portion 12 is reduced by d ₂ (> d ₁ ) from the initial thickness due to digging. Thus, the semi-transparent portion 13 region has a predetermined transmittance with respect to the exposure light by the film thickness (t ₂ ) of the remaining semi-transparent film, the dug (d ₂ ) of the transparent substrate in the translucent region, and the semi-transparent portion. It has a predetermined phase difference depending on the thickness of the translucent film (t ₂ ) in the translucent part region.

In the multi-tone photomasks 20, 21, and 22 obtained by the first to third embodiments described above, the thicknesses t ₀ , t ₁ , and t of the semi-transparent film formed in the semi-transparent part region, respectively. _{If 2} is substantially the same, as a result, the transmissivity of the semi-transparent portion with respect to the exposure light is also substantially the same, but the phase difference between the semi-transparent portion and the translucent portion is different. That is, the phase difference of the semi-transparent portion of the multi-tone photomask 22 is the largest due to the difference in the digging amount of the transparent substrate in the translucent portion region, and the phase difference of the semi-transparent portion of the multi-tone photomask 20 Is the smallest.

  As described above, according to the present invention, one type of photomask blank in which a semi-transparent film having a larger film thickness is formed in advance is prepared, and the semi-transparent portion of the semi-transparent portion region is prepared in the photolithography process. It is possible to obtain a multi-tone photomask in which the film thickness is reduced, the desired transmittance is adjusted, and the phase difference of the semi-transparent portion is adjusted with a degree of freedom according to the change in the thickness of the transparent substrate in the transparent region. I can do it.

  FIG. 5 is a diagram showing the relationship between the phase difference of the light-transmitting portion with respect to the exposure light and the effective transmittance distribution in a semi-transparent portion made of a MoSi semi-transparent film having a line width of 2 μm and an exposure light transmittance of 30%. is there. From FIG. 5, in terms of the fact that in a semi-transparent portion having a line width of 2 μm, it is preferable that a flat portion is formed in the semi-transparent portion and the cross-sectional shape of the pattern of the semi-transparent portion is vertical. Most preferably, the phase difference is 60 degrees. When the phase difference is 20 degrees, the resolution is insufficient and there are almost no flat portions, and it is difficult to select conditions for processing using a resist pattern formed using this photomask. If the phase difference is 100 degrees, unnecessary irregularities are formed in the resist pattern corresponding to the transmittance distribution in this case. In addition, as the exposure light transmittance is increased, the degree of unevenness due to the phase difference is also different, and when the pattern width is narrowed, it becomes difficult to resolve, so it is advantageous to use phase inversion by increasing the phase difference. is there. In other words, the phase difference of the semitranslucent portion to be obtained and the transmittance differ depending on what phase difference should be produced.

  According to the present invention, there is an advantage that the phase difference can be controlled with a degree of freedom in accordance with a desired transmittance and a desired pattern shape, and therefore, a resist pattern shape to be obtained by a mask user can be formed. A suitable multi-tone photomask having a desired transmittance (effective transmittance considering the influence of phase difference) distribution can be provided.

  In addition, according to the present invention, it is convenient to basically prepare one type of photomask blank on which a semi-transparent film having a larger film thickness is formed in advance. In addition, since a mask is manufactured by using a photomask blank prepared by forming a semi-transparent film and a light-shielding film in advance and then performing a patterning process by photolithography, the chance of adhesion of foreign matter is reduced. Therefore, a suitable multi-tone photomask according to the present invention can be provided according to the needs of the mask user promptly because the manufacturing process is efficient and the possibility of adhesion of foreign substances and the like is reduced. .

  Furthermore, by using the multi-tone photomask of the present invention to perform pattern transfer to a transfer target, a desired transfer pattern shape desired by the mask user can be obtained satisfactorily.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Semi-transparent film 3 Light-shielding film 4, 5 Resist film 10 Photomask blank 11 Light-shielding part 12 Light-transmitting part 13 Semi-transparent part 20, 21, 22 Multi-tone photomask 30 Transfer object 33 Resist pattern

Claims (7)

The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values,
In the method of manufacturing a multi-tone photomask, the semi-transparent portion has a predetermined transmittance, and the semi-transparent portion and the translucent portion have a predetermined phase difference from each other.
Preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate;
By patterning at least the semi-transparent film and the light-shielding film by a photolithography method, the transparent substrate surface or the translucent portion where the digging surface of the transparent substrate is exposed, and the semi-transparent layer formed on the transparent substrate A patterning step of forming a semi-transparent portion from which a part of the film thickness is removed, and a light-shielding portion in which the semi-transparent film and the light-shielding film are laminated,
The remaining film thickness of the semi-transparent film in the semi-translucent part is such that the predetermined transmittance is obtained, and the remaining film thickness of the semi-transparent film in the semi-translucent part and the translucent part The transparent substrate surface or the digging surface position is such that the predetermined phase difference is obtained , and
The patterning step includes a first photolithography step performed by forming a resist pattern in a portion other than the light-transmitting portion and a second photolithography step performed by forming a resist pattern in a portion other than the semi-transparent portion. In the first photolithography process, the exposed light shielding film is removed, and a part of the film thickness of the semi-transparent film is removed .   In the patterning step, at the portion corresponding to the light transmitting portion and the semi-light transmitting portion, simultaneous etching with the same etchant is performed, so that at least the semi-light transmitting film is etched, and the light transmitting portion and the light transmitting portion The method for manufacturing a multi-tone photomask according to claim 1, wherein a semi-translucent portion is formed. The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values,
In the method of manufacturing a multi-tone photomask, the semi-transparent portion has a predetermined transmittance, and the semi-transparent portion and the translucent portion have a predetermined phase difference from each other.
Preparing a photomask blank in which at least a semi-transparent film and a light-shielding film are formed in this order on the transparent substrate;
By patterning at least the semi-transparent film and the light-shielding film by photolithography, at least a part of the semi-transparent film remains on the translucent part where the digging surface of the transparent substrate is exposed. And a patterning step of forming a semi-transparent part and a light-shielding part in which the semi-transparent film and the light-shielding film are laminated,
The remaining film thickness of the semi-transparent film in the semi-transparent part is such that the predetermined transmittance is obtained, and the remaining film thickness of the semi-transparent film in the semi-translucent part and the translucent part The transparent substrate digging surface position is such that the predetermined phase difference is obtained , and
The patterning step includes a first photolithography step performed by forming a resist pattern in a portion other than the light-transmitting portion and a second photolithography step performed by forming a resist pattern in a portion other than the semi-transparent portion. ,
In the first photolithography process, the exposed light-shielding film and the semi-transparent film are removed, and in the second photolithography process, the exposed light-shielding film is removed, and then the light-transmitting part and the semi-light-transmitting part The translucent part and the translucent part are formed by performing simultaneous etching on the translucent film and the transparent substrate with the same etchant in a portion corresponding to A method of manufacturing a gradation photomask. The semi-transparent film and the light-shielding film formed on the transparent substrate are respectively patterned and provided with a transfer pattern including the light-shielding part, the light-transmitting part, and the semi-translucent part. A multi-tone photomask for forming a resist pattern having two or more different resist residual film values,
The semi-transparent part has a transmittance of 20 to 60% with respect to exposure light, and the semi-transparent part and the translucent part have a phase difference of 100 degrees or less with respect to the exposure light. In the mask
A transparent substrate surface or a transparent substrate where the digging surface of the transparent substrate is exposed, a semi-transparent portion in which the semi-transparent film having a predetermined thickness is formed on the transparent substrate, and the semi-transparent film and the light-shielding film are laminated. A light shielding portion,
The film thickness of the semi-transparent film in the semi-transparent part is smaller than the film thickness of the semi-transparent film in the light shielding part,
In addition, the multi-tone photomask is characterized in that the light-transmitting portion and the semi-light-transmitting portion include a surface to be etched that has been simultaneously etched by the same etchant. 5. The multi-tone photomask according to claim 4 , wherein the multi-tone photomask is used for exposure light including a wavelength range from i-line (wavelength 365 nm) to g-line (wavelength 436 nm). The multi-tone photomask is a photomask for manufacturing a thin film transistor, the light shielding portion includes a portion corresponding to a source and a drain of the thin film transistor, and the translucent portion includes a portion corresponding to a channel of the thin film transistor. The multi-tone photomask according to claim 4 , wherein the multi-tone photomask is included. Using a multi-tone photo mask according to any one of claims 4 to 6, a pattern transfer method characterized by transferring the transfer pattern onto a transfer medium by the exposure apparatus.

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