KR101173731B1 - Multi-gray scale photomask and manufacturing method thereof - Google Patents

Abstract

The multi-gradation photomask includes a transfer pattern having a light transmitting region, a light blocking region, and a semi-transmissive region. The semi-transmissive region in the transfer pattern has a first semi-transmissive portion having a first effective transmittance and a second semi-transmissive portion having a second effective transmittance different from the first effective transmittance. The first semi-transmissive portion and the second semi-transmissive portion of the resist pattern formed by developing the resist film after transferring the transfer pattern by exposing to a resist film on a transfer object using the photomask. The first effective transmittance and the second effective transmittance are set so as to have substantially the same resist residual film values in the corresponding portions.

Effective transmittance, semi-transmissive portion, resist residual film value, transfer pattern, resist pattern

Description

Multi-gradation photomask and its manufacturing method {MULTI-GRAY SCALE PHOTOMASK AND MANUFACTURING METHOD THEREOF}

The present invention relates to a multi-gradation photomask used in a photolithography step and a manufacturing method thereof.

Background Art Conventionally, in the manufacture of electronic devices such as liquid crystal displays, a photolithography step is used to expose a resist film formed on a layer to be etched using a photomask having a predetermined pattern under predetermined exposure conditions. The resist pattern is formed by transferring the pattern and developing the resist film. And a to-be-processed layer is etched using this resist pattern as a mask.

The photomask includes a multi-gradation photomask having a light shielding region for shielding exposure light, a light transmission region for transmitting exposure light, and a semi-transmission region for transmitting a part of the exposure light. When a desired pattern is transferred to a resist film (positive photoresist), which is a transfer object, by using a multi-gradation photomask including such a light-shielding region, a semi-transmissive region, and a transmissive region, the transmissive region and the semi-transmissive region of the multi-gradation photomask are transferred. Exposure light is irradiated through the area. At this time, the amount of light irradiated through the translucent region is smaller than the amount of light irradiated through the translucent region. For this reason, when developing the resist film to which exposure light was irradiated in this way, the residual film value of a resist film differs according to the quantity of irradiated light. In other words, the resist residual film value of the region irradiated with the exposure light through the semi-transmissive region of the multi-gradation photomask is smaller than the resist residual film value corresponding to the light shielding region. As described above, by performing exposure and development using a multi-gradation photomask, a resist pattern having a resist residual film value (including zero residual film value) of at least three thicknesses can be formed.

As described above, in the case of etching a target object on which a resist film is formed by using a resist film including regions having different resist residual film values, first, the area of the residual film value zero (area exposed to the target: light-transmitting area of the multi-gradation photomask) Region), and then the resist film is reduced by ashing. As a result, the region of the resist film having a relatively thin thickness (region corresponding to the semi-transmissive region of the multi-gradation photomask) is removed, and the object to be treated at that portion is exposed. Then, the exposed workpiece is etched. Therefore, a multi-gradation photomask that realizes a resist pattern having a plurality of different resist residual film values is extremely useful because it is possible to streamline the photolithography process by reducing the number of photomasks used.

As an example of patterning using such a multi-gradation photomask, there is a method disclosed in Patent Document 1 (Japanese Patent Laid-Open No. 2000-111958). This method manufactures the thin film transistor manufactured conventionally by the etching process using 5 or 6 photomasks by the etching process using 4 photomasks. In this method, the use of photomasks having three or more transmittances is described.

In the processing of the object to be processed using the multi-gradation photomask, it is important to precisely control the resist residual film value precisely in order to reduce the predetermined amount of the resist film in the figure as described above. In this way, if the resist residual film value is not precisely and precisely controlled, the processing step becomes remarkably complicated and the production efficiency is lowered.

This invention is made | formed in view of such a point, Comprising: It aims at providing the multi-gradation photomask and its manufacturing method which become able to control resist residual film precisely and precisely in the process of the to-be-processed object using a multi-gradation photomask. It is done.

The multi-gradation photomask of the present invention comprises a transfer pattern having a light-transmitting region, a light-shielding region, and a semi-transmissive region by a light shielding film that shields exposure light and a semi-transmission film that partially transmits the exposure light. A multi-gradation photomask provided, wherein the semi-transmissive region in the transfer pattern includes a first semi-transmissive portion having a first effective transmittance and a second semi-transmissive portion having a second effective transmittance different from the first effective transmittance, The first semi-transmissive portion and the second semi-transmissive portion of the resist pattern formed by developing the resist film after transferring the transfer pattern by exposing to a resist film on a transfer object using the photomask. The first effective transmittance and the second effective transmittance are set so that the corresponding portion has substantially the same resist residual film value.

In the multi-gradation photomask of the present invention, the first effective transmittance and the second effective transmittance are determined using at least one of the line width, the shape of the first semi-transmissive portion and the second semi-transmissive portion, and the film transmittance of the semi-transmissive membrane. It is preferable that it is determined. In this case, it is preferable that the said 1st semi-transmissive part and the said 2nd semi-transmissive part are comprised by the translucent membrane of a film transmittance respectively. In addition, it is preferable that the said 1st translucent part and the said 2nd translucent part differ in film transmittance by difference of the laminated structure of each transflective film. In addition, it is preferable that the said 1st translucent part and the said 2nd translucent part differ in film transmittance | permeability from each other by difference of the film thickness of each transflective film.

In the multi-gradation photomask of the present invention, the first semi-transmissive portion has a portion in which unit patterns are repeatedly arranged, and the second semi-transmissive portion is a portion in which unit patterns different from the first semi-transmissive portion are repeatedly arranged. It is preferable to have. For example, it is preferable that the former part corresponds to the pixel pattern of a liquid crystal display device, and the latter part corresponds to the peripheral circuit pattern of a liquid crystal display device.

In the multi-gradation photomask of the present invention, the semi-transmissive region is preferably a region sandwiched between a plurality of adjacent light shielding films.

In the multi-gradation photomask of the present invention, it is preferable that, in the multi-gradation photomask, the semi-transmissive region is composed of a fine pattern having a resolution limit or less.

The manufacturing method of the multi-gradation photomask of this invention has a light-transmitting area | region, light-shielding area | region, and semi-transmissive area | region by patterning the light shielding film which shields exposure light, and the semi-transmission film which partially transmits the exposure light, formed on the transparent substrate. A method of manufacturing a multi-gradation photomask formed by forming a transfer pattern, wherein the transfer pattern is formed by exposing to a resist film on a transfer object using the photomask to transfer the transfer pattern, and then developing the resist film. The portions corresponding to the first semi-transmissive portion having the first effective transmittance and the second semi-transmissive portion having the second effective transmittance different from the first effective transmittance of the resist pattern each have substantially the same resist remaining film value. A first semi-transmissive portion and the second semi-transmissive portion are formed.

In the manufacturing method of the multi-gradation photomask of the present invention, the first effective transmittance and the second effective transmittance are at least one of a line width, a shape of the first semi-transmissive portion and the second semi-transmissive portion, and a film transmittance of the semi-transmissive membrane. It is preferable to determine using. In this case, it is preferable to form the first semi-transmissive portion and the second semi-transmissive portion using semi-transmissive membranes having different film transmittances, respectively. Moreover, it is preferable to form the said 1st translucent part and the said 2nd translucent part from which film transmittance | permeability differs using the transflective film of the laminated structure which respectively differs. In addition, it is preferable to form the first semi-transmissive portion and the second semi-transmissive portion having different film transmittances by using semi-transmissive membranes having different film thicknesses, respectively.

In the manufacturing method of the multi-gradation photomask of this invention, it is preferable that the said semi-transmissive area | region is comprised by the fine pattern below the resolution limit in the said multi-gradation photomask.

The pattern transfer method of the present invention is characterized in that the transfer pattern is transferred to a resist film formed on a target object using the multi-gradation photomask.

The multi-gradation photomask of the present invention comprises a transfer pattern having a light-transmitting region, a light-shielding region, and a semi-transmissive region by a light shielding film that shields exposure light and a semi-transmission film that partially transmits the exposure light. A photomask provided, wherein the semi-transmissive region in the transfer pattern includes a first semi-transmissive portion having a first effective transmittance and a second semi-transmissive portion having a second effective transmittance different from the first effective transmittance. The pattern corresponds to the first semi-transmissive portion and the second semi-transmissive portion of the resist pattern formed by developing the resist film after transferring the transfer pattern by exposing the resist film on the transfer object using the photomask. The first effective transmittance and the second effective transmittance are set so as to form substantially the same resist residual film value at the portion to be formed. In the processing using the processing target, it is possible to make precise and tight control of the resist glass makchi.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail with reference to an accompanying drawing.

The present inventors have already noted that in order to obtain a desired resist residual film value on the transfer object, it is insufficient to merely control the film transmittance of the semi-transmissive film used in the semi-transmissive portion of the multi-tone mask. In order to determine the resist residual film value at the time of obtaining the portion of the film, not only the exposure light transmittance as a film of the semi-transmissive film used for the mask, but also the shape of the pattern formed in the mask, the optical characteristics of the light source used for exposure, etc. We found that the phenomenon must be considered. Therefore, the present inventors have previously proposed an effective light transmittance (effective transmittance) T _A for transmitting a mask instead of the film transmittance T _{f of the} semi-transmissive membrane and controlling this effective transmittance.

MEANS TO SOLVE THE PROBLEM This inventor examined the method which can manufacture the outstanding photomask which is easy to process for a mask user more by performing a high degree of control. It demonstrates below.

As described above, conventionally, when processing a target object using a multi-gradation photomask, a resist exposure film having a desired residual film value is formed in a resist film on the target object, having a specific exposure light transmittance. A photomask having a translucent region is used. For example, a three-gradation photomask having a translucent region in addition to the transmissive region and the light shielding region is considered. At this time, it is desired that the resist residual film value on the processing target object formed by the semi-transmissive region be uniform in plane. At least, if the resist residual film value does not fall within a predetermined allowable range at any position in the surface, it is unsuitable when etching the resist residual film as a photomask. Therefore, it is preferable to manage the effective transmittance T _A of the semi-transmissive region in the transfer pattern formed on the photomask so that the same exposure light transmittance is effectively obtained in all the semi-transmissive regions. In addition, this effective transmittance T _A can be considered as the transmittance which the translucent area | region of the photomask, for example, transmits exposure light under the exposure conditions actually used. In fact, as shown in FIG. 1, the peak value of the light transmission curve of a semi-transmissive area can be made into effective transmittance.

By the way, when the resist film which is a to-be-transferred body is exposed and a resist pattern is formed on a to-be-processed object using such a multi-gradation photomask, the resist residual film value of the area | region corresponding to the said semi-transmissive area is not necessarily made constant. The phenomenon was found.

For example, a photomask is a photomask for manufacturing a liquid crystal display device, and in a transfer pattern, a pixel pattern corresponding to a pixel and a pattern for a peripheral circuit corresponding to a circuit near the outer circumference of the transfer pattern may coexist. In this case, the semi-transmissive area is included in the pixel pattern and the peripheral circuit pattern. Even if the photomask is designed in advance so that the respective effective transmittances are the same, when the resist film on the object to be processed is exposed using the photomask, the semi-transmissive region in the pixel pattern and the semi-transmissive region in the peripheral circuit pattern are exposed. And the resist residual film value corresponding to each may differ.

The pattern shape of the pixel pattern and the peripheral circuit pattern is different from each other, and the area ratio of the line width (CD) of the portion corresponding to the semi-transmissive region or the light-transmitting region / shielding region / semi-transmissive region including the surrounding pattern is also different from each other. different. Therefore, even if the effective transmittance of the photomask is made constant, the resist remaining film value corresponding to the semi-transmissive region is affected by factors other than the photomask. On the other hand, it was discovered that some kind of regularity and reproducibility are seen in factors other than such a photomask. In addition, as another factor, for example, the possibility that the exposure amount has an in-plane distribution due to the difference between exposure units is also considered.

For the mask user, from the standpoint of convenience of processing of the transfer object, it is most desired that the residual film value is a desired value and that the variation in the residual film value is small. In other words, in order to obtain a predetermined resist remaining film value R _T , an appropriate photomask may be designed after reflecting a resist processing process such as actual exposure conditions and developing conditions. Therefore, it is not necessary that T _A for the semi-transmissive region of any photomask is constant, and T _A should be controlled to make R _T constant. From that point of view, it is not necessary to separately examine the causes of non-uniformity of R _T , and as a result, a photomask should be designed in order to obtain an excellent resist pattern.

Here, a three-gradation photomask including a light transmitting area, a light blocking area, and a semi-transmissive area will be described as an example. The same problem may arise in the semi-transmissive area | region which made arbitrary predetermined | prescribed effective transmittance also in one or more gradation photomasks. Therefore, it is required to solve the problem similarly.

That is, in the multi-gradation photomask of the present invention, the semi-transmissive region in the transfer pattern is different from the first semi-transmissive portion having the first effective transmittance such that the resist residual film value R _T is constant. A second semi-transmissive portion having a second effective transmittance and having a shape different from that of the first semi-transmissive portion, and the transfer pattern is exposed to a resist film on the transfer object using the photomask to transfer the transfer pattern, The first effective transmittance and the second effective transmittance are set to form substantially the same resist residual film value in a portion corresponding to the first transflective portion and the second transflective portion of the resist pattern formed by developing the resist film. It is characterized by that.

According to such a structure, the resist residual film value can be precisely and precisely controlled in the process of the to-be-processed object using a multi-gradation photomask, and it can raise the productivity and yield of manufacturing processes, such as a liquid crystal display device, by this. .

The multi-gradation photomask in the present invention refers to a photomask of three or more gradations including a light shielding region, a light transmissive region, and a semi-transmissive region. That is, in this multi-gradation photomask, by having semi-transmissive regions other than the light shielding region and the transmissive region, regions having a plurality of film thicknesses are formed in the resist pattern formed on the object to be processed. The light blocking area may substantially shield exposure light, and the light transmitting area may be formed by exposing a transparent area such as a transparent substrate. The semi-transmissive region is a portion where the transmittance is relatively smaller than that of the transmissive region, and is a region for forming a desired resist residual film on the workpiece. This translucent region can be formed by, for example, forming a translucent film having a predetermined film transmittance on a transparent substrate. When the transmissive region is 100%, the film transmittance of the semi-translucent membrane is 10% to 70%, and more preferably 20% to 60%. Moreover, you may make it a semi-transmissive area | region by forming the pattern of the line width below the resolution limit of an exposure machine in the light shielding film formed on the transparent substrate. The present invention can also be similarly applied to four or more gradation photomasks having a resist pattern having three or more resist residual film values.

The film transmittance T _f refers to the transmittance of the semi-transmissive region in an area sufficiently large with respect to the resolution limit under the exposure conditions when the semi-transmissive membrane is formed on the transparent substrate to form the semi-transmissive region. On the other hand, since the actual transmittance is affected by the line width of the pattern and the like, it is useful to define the exposure light transmittance of the semi-transmissive region in the actual pattern by the effective transmittance T _A.

Since the effective transmittance is an index in consideration of optical conditions and pattern design in addition to the transmittance inherent to the film, it is an index that accurately reflects the situation of the residual film value, and is suitable as an index for management of the residual film value. In addition, as effective transmittance | permeability, it can be set as the transmittance | permeability of the part which has the maximum value in the light intensity distribution which permeate | transmits the semi-transmissive area, when the exposure light transmittance of the translucent area is 100%. This is because, for example, using this photomask, when a resist pattern of a positive resist is formed on a transfer object, it has a correlation with the minimum value of the resist residual film value which arises in a semi-transmissive area | region. Such range management is particularly effective when, for example, the width of the channel region of the thin film transistor is 5 µm or less.

As mentioned above, as an apparatus for measuring an effective transmittance, the apparatus shown in FIG. 2 is mentioned, for example. This apparatus comprises a light source 1, an irradiation optical system 2 for irradiating light from the light source 1 to the photomask 3, and an objective lens system 4 for forming an image transmitted through the photomask 3. And the imaging means 5 for imaging the image obtained through the objective lens system 4.

The light source 1 emits a light beam having a predetermined wavelength, and for example, a halogen lamp, a metal halide lamp, a UHP lamp (ultra high pressure mercury lamp), or the like can be used.

The irradiation optical system 2 guides the light from the light source 1 to irradiate the photomask 3 with light. This irradiation optical system 2 is provided with an aperture mechanism (opening aperture 7) in order to make the numerical aperture NA variable. It is preferable that this irradiation optical system 2 is provided with the visual field stop 6 for adjusting the irradiation range of the light in the photomask 3. The light passing through this irradiation optical system 2 is irradiated to the photomask 3 held by the mask holder 3a. This irradiation optical system 2 is disposed in the case 13.

The photomask 3 is held by the mask holder 3a. The mask holder 3a supports the lower end of the photomask 3 and the vicinity of the side edges of the photomask 3 while the main plane of the photomask 3 is substantially vertical, and tilts the photomask 3. It is fixed and kept. The mask holder 3a is a photomask 3 that can hold a large size (for example, 1220 mm x 1400 mm in a main plane and 13 mm in thickness) and a photomask 3 of various sizes. It is supposed to be. In addition, an approximately perpendicular means that the angle from the perpendicular | vertical represented by (theta) in FIG. 2 is within about 10 degrees. Light irradiated to the photomask 3 passes through the photomask 3 and enters the objective lens system 4.

The objective lens system 4 includes, for example, a first group (simulator lens) 4a in which light that has passed through the photomask 3 is incident to apply infinity correction to the light beam, thereby forming parallel light; It consists of the 2nd group (imaging lens) 4b which forms the light beam which passed through 1 group. The simulator lens 4a is provided with an aperture mechanism (opening aperture 7), and the numerical aperture NA is variable. The light beam passing through the objective lens system 4 is received by the imaging means 5. This objective lens system 4 is disposed in the case 13.

The imaging means 5 captures an image of the photomask 3. As this imaging means 5, imaging elements, such as CCD, can be used, for example.

In this apparatus, since the numerical aperture of the irradiation optical system 2 and the numerical aperture of the objective lens system 4 are respectively variable, the ratio of the numerical aperture of the irradiation optical system 2 to the numerical aperture of the objective lens system 4, that is, The sigma value (σ: coherency) can be varied. By appropriately selecting the above conditions, the optical conditions at the time of exposure can be reproduced or approximated.

Moreover, in this apparatus, the control means which has the calculation means 11 and the display means 12 which perform image processing, an operation, the comparison with a predetermined threshold value, and display with respect to the picked-up image obtained by the imaging means 5, etc. The movement operation means 15 which changes the position of 14 and the case 13 is provided. For this reason, a predetermined calculation is performed by a control means using the obtained captured image or the light intensity distribution obtained based on this, and the picked-up image under the conditions using other exposure light, or light intensity distribution and transmittance | permeability can be calculated | required. have.

In the apparatus shown in Fig. 2 having such a configuration, since the NA and sigma values are variable and the source of the light source can be changed, the exposure conditions of various exposure apparatuses can be reproduced.

Further, as the effective transmittance T _A, in this case, and a transmittance at a maximum value (this is equivalent to the resist film, glass bottom) of the light intensity distribution curve at half the transmissive area. In other words, the effective transmittance T _A is a semi-transmissive region sandwiched between adjacent light shielding films, and the light intensity distribution curve of the transmitted light is a steering curve and refers to the transmittance corresponding to the peak. This effective transmittance is determined by the actual exposure conditions (optical parameters, spectral characteristics of the irradiated light) and the actual photomask pattern. However, in order to simplify, exposure conditions can be replaced by model conditions. This condition is, for example, using an optical system having a numerical aperture of 0.08 and a coherency of 0.8, and an exposure condition using irradiated light having an intensity of 1: 1, 1: 1 of g-line, h-line, and i-line. can do.

The multi-gradation photomask according to the present invention comprises a light shielding film for shielding exposure light and a semi-transmission film for partially transmitting the exposure light, which is formed on a transparent substrate, to form a light transmission region, a light shielding region, and a semi-transmission region. It has a pattern.

A glass substrate etc. are mentioned as a transparent substrate. Moreover, as a light shielding film which shields exposure light, metal silicide films, such as metal films, such as a chromium film, a silicon film, a metal oxide film, and a molybdenum silicide film, etc. are mentioned. In addition, the light shielding film preferably has an antireflection film on its surface, and examples of the material of the antireflection film include chromium oxide, nitride, carbide, fluoride and the like. As the semi-transmissive film which partially transmits the exposure light, an oxide of chromium, nitride, carbide, oxynitride, oxynitride carbide, metal silicide or the like can be used. In particular, metal silicide films such as chromium oxide films, chromium nitride films, and molybdenum silicide films, and oxides, nitrides, oxynitrides, carbides, and the like are preferable.

In the multi-gradation photomask of the present invention, the first effective transmittance and the second effective transmittance are set to have substantially the same resist residual film value when exposure and development are performed on the resist film on the target object using the photomask. It is preferable that it is done. Here, the substantially same resist residual film value is such that processing conditions can be determined under constant conditions over the surface when etching the target object (for example, a thin film) using the resist pattern as a mask. For example, when a predetermined resist residual film is formed by a semi-transmissive region sandwiched between adjacent light shielding regions of the photomask, a light transmission curve (inside the rectangle in FIG. 1) of the semi-transmissive region is formed on the resist film. The same resist pattern as above is formed by vertically inverting the shape in the rectangle in Fig. 1. For example, as long as the film thickness of the peak portion (that is, the bottom portion in the resist residual film) in the light transmission curve is within 20 nm, more preferably within 10 nm, it is possible to have substantially the same resist residual film value. .

In the multi-gradation photomask of the present invention, the semi-transmissive region in the transfer pattern includes a first semi-transmissive portion having a first effective transmittance for making the resist residual film value R _T constant, and a second different from the first effective transmittance. It has an effective transmittance and has a 2nd semi-transmissive part of a shape (for example, pattern) different from the said 1st translucent part. In this case, the first translucent portion and the second translucent portion will be described.

In an actual photomask (for example, the mask for manufacturing a thin film transistor for a liquid crystal display device), a repeating pattern corresponding to a pixel is arranged. In many individual pattern, TFT pattern as shown to Fig.3 (a) is formed. Thus, by using the pattern of the design shown in Figure 3 (a), it will be described with respect to the mask design considering the effective transmittance T _A. Ab in FIG. 3A corresponds to the source / drain region of the TFT, and Aa in FIG. 3A corresponds to the channel region. In the three-gradation photomask including such a pattern in the transfer pattern, as shown in Fig. 3B, the Aa region is composed of the light shielding film 23, and the Ab region is composed of the translucent film 22. do. In addition, the code | symbol 21 in a figure represents a transparent substrate.

However, in the actual TFT manufacturing photomask, there is a pixel pattern region provided by arranging a plurality of unit patterns as shown in Fig. 3A, and the outer periphery of the pixel pattern region is the same as in Fig. 3A. The peripheral circuit pattern area | region in which many unit patterns of the shape of or the unit pattern of a different shape is arranged is formed in many cases. That is, a pattern corresponding to a pixel pattern of a liquid crystal display device having a portion in which unit patterns are repeatedly arranged, and a pattern corresponding to a peripheral circuit pattern of the liquid crystal display device in which a unit pattern different from this pattern is repeatedly arranged. It is a pattern having. In these two regions, the arrangement density of the patterns is also different, the dimensions of the patterns are often different, and the area ratios of the light shielding region, the light transmissive region, and the semi-transmissive region also differ depending on the arrangement of the patterns. Alternatively, a plurality of different channel patterns may exist in the pixel, or different peripheral circuit patterns may exist in the outer peripheral portion or the like. In this case, the dimensions, shapes, arrangement density, etc. of the plurality of channel patterns or the plurality of peripheral circuit patterns may be different.

By the way, when the mask pattern shown to Fig.3 (a) is exposed on exposure conditions using an actual exposure machine, the light corresponding to the part along the IIIB-IIIB line of Fig.3 (a) of the transfer image which arises on a to-be-transferred body is shown. The intensity distribution is as shown in FIG. Here, exposure conditions are as follows.

NA (opening number) of the exposure machine: 0.085

σ (coherency): 0.9

Exposure wavelength: i line-g line

Intensity ratio: g / h / i = 1.0 / 0.8 / 0.95

The semi-transmissive region is formed by forming a MoSi film on a transparent substrate, and the composition and the film thickness are adjusted so that the light transmittance of the semi-transmissive region is 44% at g line. In addition, the phase difference between the transmitted light of the transflective area and the transmitted light of the transmissive area in a transparent substrate is less than 30 degrees. When the phase difference between the transmitted light of the translucent region and the transmitted light of the transmissive region in the transparent substrate is less than 30 degrees, light intensity distribution for forming a desired resist pattern on the transfer object is realized. In addition, the standard dimension of the channel width (also called channel length) (width of the semi-transmissive area) of the pattern was set to 3.7 µm. The transmittance curve when the channel width is increased and decreased in units of 0.1 mu m is the curve shown in FIG. 4 is an enlarged view of a portion enclosed by a square in FIG. 1 and 4, the vertical axis is the effective transmittance T _A.

As apparent from Figs. 1 and 4, by changing the width of the semi-transmissive region, the maximum value of the light intensity distribution curve changes up and down. That is, the minimum value (bottom of a residual film shape) of the resist pattern exposed and formed by this photomask changes also. It is understood that the residual film value changes depending on the pattern shape (line width) even when the same translucent film having an exposure light transmittance of 44% g line is used. The maximum value (peak) of light intensity distribution is as showing in following Table 1.

The said light intensity distribution curve can also be obtained by exposing to the model mask actually created using the exposure machine actually used, and imaging by arrange | positioning an imaging means in the to-be-transferred body surface (hardware simulation). Alternatively, optical conditions can be specified and simulated by software (software simulation).

From the above results, the correlation between the channel width and the effective transmittance T _A is shown in FIG. 5.

This curve can be approximated by the following quadratic formula (Equation 1) in the range of 3.0 micrometers-4.4 micrometers of channel widths.

By using this equation (1), in the case where the desired effective transmittance is to be obtained, the channel width (line width of the semi-transmissive region) can be determined by using the above-mentioned semi-transmissive film. For example, when it is intended to be 2% lower in the effective transmittance T _A than the current design (CD = 3.7 µm) (that is, to thicken the residual film), the effective transmittance T _A may be set from 37.2% to 35.2%. Thereby, if from Fig. 5 and Equation (1), as near to the CD T _A = 35.2%, with the design value of janmak part to increase the 3.4㎛. On the contrary, in the case where the effective transmittance T _{A is} to be 2% higher (that is, the remaining film is thinner) than the current design, T _A = 39.2% may be used. Therefore, CD = 4.1 µm may be considered as the design value. By thinking in this way, it is very advantageous to define the effective transmittance T _A in terms of controllability of the resulting resist remaining film value rather than defining the transmittance of the multi-gradation photomask only by the film transmittance T _f . As a means for adjusting the effective transmittance T _A , there are other methods described later besides CD adjustment.

By the way, in the actual photomask, as mentioned above, different pattern regions exist. Even if the pattern regions are different, the resist residual film amount is preferably constant. Therefore, using the relationship between the effective transmittance and the line width obtained above, the pattern line width was adopted in each pattern area so as to have the same effective transmittance and exposed. By the way, between the different pattern areas, the formed resist residual film value did not become constant. According to the examination, the factors which influence the resist residual film value formed on a to-be-transferred body by factors other than a mask include the following.

1) Optical characteristics of the exposure machine, and optical characteristics of the illumination

2) In-plane nonuniformity of exposure light exposure amount

3) The difference of resist processing characteristic (especially image development characteristic) by the difference of a pattern

Among these, about 1) can be reflected in an effective transmittance. However, about 2) and 3), since the resist pattern is actually made after forming a resist pattern in many cases, these factors were not conventionally reflected in the mask design. For example, in the pixel pattern region and the peripheral circuit pattern region, the arrangement density of the pattern is also different and the dimensions of the pattern are often different, and the area ratio of the light shielding region, the light transmissive region, and the semi-transmissive region is determined by the arrangement of the patterns. Many different cases are seen. For this reason, in both regions, depending on the above difference, development behavior and development efficiency are different, and it is considered that the residual film value of the resulting resist pattern is also different from each other by this effect.

It is assumed that the pattern shown in Fig. 3A is disposed in the pixel pattern region and the peripheral circuit pattern region of the photomask, respectively (the reference design line width of the semi-transmissive region is 3.7 mu m). However, in both regions, the array density of the patterns and the area ratios of the light shielding region, the light transmissive region, and the semi-transmissive region are different. Here, how the mask design may be improved in order for the resist residual film values of both regions to become equal under these conditions is examined. That is, in both regions, it is considered whether the resist residual film value R _T becomes constant if each having an effective transmittance T _A (wherein the resist residual film value R _T is a minimum value (bottom) in the resist pattern shape of the semi-transmissive region). Refers to the thickness of).

This inventor actually performed the exposure test using the test mask on the to-be-processed target object using the predetermined exposure apparatus. When this resist film was developed and the shape was measured, the result shown in FIG. 6 and Table 2 was obtained. It is also an object of the experiment is effective transmittance T _A and the resist glass, but to obtain the correlation between makchi R _T, as a means for obtaining a resist glass makchi R _T of time is changed the effective transmittance T _A, an aligner light amount (hereinafter referred to as dose changing also known) and to measure the change in the resist glass makchi R _T associated to it. It can be seen that the residual film behavior between the pixel pattern region and the peripheral circuit pattern region is clearly different.

Here, since the exposure amount D _A actually received by the resist is dose amount x effective transmittance T _A , the horizontal axis is converted into the effective exposure amount D _A. The results are shown in Figure 7 and Table 3. Since the line width is 3.7 µm, the effective transmittance T _A is 37.2% (see Table 1).

As shown in FIG. 7, the resist residual film value R _T in the pixel pattern region and the peripheral circuit pattern region can be approximated by the following equations (2) and (3).

Using this approximation formula, the effective exposure amount D _A with respect to the resist residual film value to obtain is as showing in Table 4.

Here, when the dose is fixed at 80 mJ / cm 2, as shown in Table 5, the relationship between the resist residual film value R _T and the effective transmittance T _A is obtained. That is, even if the resist residual film value to be obtained is the same, in the above example, in the semi-transmissive region of the pixel pattern region and the semi-transmissive region of the peripheral circuit pattern region, a mask design having a difference of about 2% around the effective transmittance T _{A is obtained} . You must Of course, this adjustment amount changes depending on the resist residual film value to be obtained, and also changes depending on the design of the pattern and the arrangement of the pattern. However, since any exposure condition or pattern design is determined, it is a phenomenon that appears reproducibly, and therefore the application of the above method is certainly advantageous. That is, in consideration of the change of the developing speed resulting from the difference of a pattern or arrangement | positioning, such as the loading effect which arises in the processing process of a to-be-processed object, the in-plane distribution of the exposure light amount which originates in an exposure machine, etc., those effects are canceled, and a to-be-processed object The photomask can be designed to reliably perform the etching process under predetermined conditions.

In the present invention, it is assumed that the exposure conditions and the process conditions are similarly applied in the photolithography process using the test mask and the photolithography process using the photomask to be obtained.

According to the above study, it can be seen that the adjustment of the effective transmittance T _A possible to obtain a desired resist glass makchi. Next, how to prepare a mask pattern having the effective transmittance T _A will be described. For example, the first semi-transmissive portion and the second semi-transmissive portion respectively corresponding to the pixel pattern region and the peripheral circuit pattern region are intended to have the same resist residual film value, and for this reason, the effective transmittance T _A is assumed to be different.

When the effective transmittance T _A of the first semi-transmissive portion and the second semi-transmissive portion is different from each other, it can be determined using at least one of the line width, the pattern shape, and the film transmittance of the translucent film. have. The difference between the effective transmittances T _A of the first semi-transmissive portion and the second semi-transmissive portion is that the bottom portion is the same in the residual film profile when the resist film is exposed and developed, that is, the residual film values of the first and second semi-transmissive portions are the same. Is set to.

First, as shown in (a) and (b) of FIG. 8, the film transmittance can be made different in the first semi-transmissive portion and the second semi-transmissive portion by the laminated structure of different translucent films. For example, one side is made into laminated structure and the other side is made into single layer. In the structure shown to Fig.8 (a), the 1st semi-transmissive film 34 and the 2nd semi-transmissive film 35 are used for the 1st semi-transmissive part B (dark translucent area | region), and the 2nd semi-transmissive part C The second translucent film 35 is used for (bright translucent region). As the material of the second semi-transmissive film 35, chromium nitride, chromium oxide, oxynitride mainly containing MoSi (MoSi ₂ ), MoSiN, MoSiON, MoSiCON, or chromium, which is composed mainly of molybdenum silicide (MoSi) Chromium, chromium fluoride, and the like.

In the configuration shown in FIG. 8B, the first semi-transmissive membrane 34 and the second semi-transmissive membrane 35 are used for the first semi-transmissive portion B (dark translucent region), and the second semi-transmissive portion C is used. The second translucent film 35 is used for (bright translucent region). Examples of the material of the second semi-transmissive film 35 include MoSi (MoSi ₂ ), MoSiN, MoSiON, MoSiCON, and the like having molybdenum silicide (MoSi) as a main component. As the material of the first translucent film 34, chromium nitride, chromium oxide, chromium oxynitride, chromium fluoride, or the like is preferable.

In the structure shown to Fig.8 (a), (b), as a material of the 1st semi-transmissive film 34, the thing chosen from the same material as the said 2nd translucent film 35 can be used. The transmittance of the first translucent portion B is set by the selection of the film material and the film thickness of each of the first translucent membrane 34 and the second translucent membrane 35, and the transmittance of the second translucent portion C is It is set by selection of the film material and the film thickness of the first translucent film 34. 8A to 8D, reference numeral 31 denotes a transparent substrate, reference numeral 32 denotes a light shielding film, and reference numeral 33 denotes an antireflection film.

Next, as shown in FIG.8 (c), you may comprise the 1st semi-transmissive part B and the 2nd semi-transmissive part C with the semi-transmissive film of a film transmittance respectively. In the configuration shown in FIG. 8C, the first semi-transmissive membrane 34 is used for the first semi-transmissive portion B (dark translucent region), and the second semi-transmissive portion C (bright translucent region) is used for the second. By using the semi-transmissive film 35, each semi-transmissive area is composed of a single layer. As a material of the first half-transparent film 34, for example, can be cited as a main component of molybdenum silicide (MoSi), MoSi (MoSi _2), MoSiN, MoSiON, MoSiCON like. As the material of the second semitransmissive film 35, chromium nitride, chromium oxide, chromium oxynitride, chromium fluoride and the like are preferable.

Next, as shown in (d) of FIG. 8, in the first semi-transmissive portion B and the second semi-transmissive portion C, the film transmittances may be different from each other by the film thicknesses of the different semi-transmissive membranes. In the configuration shown in FIG. 8D, the semi-transmissive film 34 is formed on the first semi-transmissive portion B and the second semi-transmissive portion C, and the thickness of the semi-transmissive membrane 34 of the first semi-transmissive portion B is increased. The thickness of the transflective film 34 of the second translucent portion C is made thin. Such a configuration can, for example, perform etching with a partial chemical solution on the semitransmissive film by two photolithography processes using a photoresist to form portions having different film thicknesses. As the semi-transmissive film, an oxide of chromium, nitride, carbide, oxynitride, oxynitride carbide, metal silicide or the like can be used. In particular, metal silicide films such as molybdenum silicide (MoSix) films and the like are preferable.

As shown in (a) ~ (d) of Figure 9, may be different from each other the effective transmittance T _A by 1 from the semi-shielding portion and the second semi-shielding portion, each of different line width (CD). In the configuration shown in FIG. 9A, the line widths of the patterns of the light shielding film 32 and the anti-reflection film 33 are different from each other (line width: Wc, line width: Wd), and the effective transmittance T _A of the semi-transmissive region. Are doing differently. In addition, in the configuration shown in FIG. 9B, the effective transmittance T _A of the semi-transmissive region is different from each other by changing the pattern of the semi-transmissive film 34 (monolayer film: Pc, the pattern below the resolution limit: Pd). Doing.

In addition, (c) of Fig. 9, as shown in (d), without using the semi-transparent film 34, the light-shielding film 32 (and the anti-reflection film 33) by the effective transmittance T _A, respectively The first semi-transmissive portion c and the second semi-transmissive portion d may be different from each other. In this case, as shown in Fig. 9C, all the patterns may be fine patterns (e.g., fine lines or dots) below the resolution limit, and as shown in Fig. 9D. Similarly, fine patterns below the resolution limit and patterns of resolvable line widths may be mixed.

Therefore, by the above-described means, the change in the resist residual film value is grasped, and based on this result, the first semi-transmissive portion and the second semi-transmissive portion (as a result, the effective transmittances T _A are different from each other) are obtained. Mask design can be performed.

The first semi-transmissive portion and the second semi-transmissive portion of the resist pattern formed by developing the resist film after transferring the transfer pattern by exposing to such a multi-gradation photomask, that is, a resist film on a transfer object, are transferred. In the case of manufacturing a multi-gradation photomask which forms substantially the same resist residual film value at the portion to be exposed, the resist film formed on the test target object is exposed using a test mask in which a test transfer pattern having a semi-transmissive region is formed. By measuring the resist residual film value of the developed test resist pattern, the first semi-transmissive portion having the first effective transmittance and the first effective transmittance different from each other are determined based on the correlation between the effective transmittance of the semi-transmissive region and the remaining film value. A transfer pattern having a second semi-transmissive portion having a second effective transmittance may be formed.

That is, a test resist is formed by exposing the test pattern onto a test transfer member using a test mask having a test transfer pattern having a translucent portion, transferring the test pattern to a resist film on the test transfer member, and then developing the test resist. By measuring the resist residual film value of the pattern, the correlation between at least one of the line width of the semi-transmissive part, the shape of the semi-transmissive part, and the film transmittance of the semi-transmissive film used in the semi-transmissive part and the formed resist residual film value are determined. Based on this, the first semi-transmissive portion and the second semi-transmissive portion are formed to have different first effective transmittance and second effective transmittance, respectively. In this manner, the first semi-transmissive portion and the second semi-transmissive portion may be formed to have different first effective transmittance and second effective transmittance, respectively, using separately acquired parameters.

Alternatively, a test resist is formed by exposing the test pattern onto a test transfer member using a test mask having a test transfer pattern having a translucent portion, transferring the test pattern to a resist film on the test transfer member, and then developing the test resist. By measuring the resist residual film value of the pattern, the correlation between the effective transmittance of the semi-transmissive portion and the resist residual film value formed thereby is determined. Based on the correlation, the first effective transmittance and the second effective transmittance different from each other are determined. The first semi-transmissive portion and the second semi-transmissive portion are formed. In this manner, the correlation may be obtained through an effective transmittance. In this case, the first effective transmittance is determined by determining at least one of the line widths of the first and second semi-transmissive portions, the pattern shape of the semi-transmissive portion, and the film transmittance of the semi-transmissive membrane used in the translucent portion. And a first semi-transmissive portion and a second semi-transmissive portion having a second effective transmittance.

Based on the technical matters described above, the correlation between the effective transmittance or the effective exposure amount under the predetermined exposure conditions and the resist remaining film value of the resist pattern formed on the transfer object is determined, and based on the correlation, a desired resist is obtained. By determining the photomask pattern for obtaining the effective transmittance or the effective exposure amount for obtaining the residual film value and for providing the effective transmittance or the effective exposure amount, the resist residual film value was controlled in the resist film on the transfer object by exposure. A photomask having a photomask pattern for forming a resist pattern can be designed. In this case, the correlation between the effective transmittance or the effective exposure amount and at least one of the line width, the film transmittance, and the pattern shape of the predetermined portion of the photomask pattern is obtained beforehand, and the effective transmittance or After obtaining the effective exposure amount, it is preferable to determine at least one of the line width, the film transmittance, and the pattern shape of the predetermined portion of the photomask pattern which provides the effective transmittance or the effective exposure amount.

Here, the test mask is a preliminary mask for precisely and precisely designing the actual mask to be obtained. Preferably, an actual mask approximation pattern (test transfer pattern) is formed on the premise of design fine adjustment. This is exposed under the exposure conditions to be applied to the actual mask. In addition, when measuring the resist pattern formed on a to-be-processed object using a test mask, the thing similar to the process of processing the resist pattern formed on a to-be-processed object using an actual mask is applied.

Next, the Example performed in order to clarify the effect of this invention is demonstrated.

First, the multi-gradation photomask 41 in which the transfer pattern 42 for TFT manufacture for liquid crystal display devices as shown in FIG. 10 was formed was prepared. This pattern has a pixel pattern region 42a at the center and a peripheral circuit pattern region 42b at its outer periphery.

This multi-gradation photomask 41 is manufactured by the process shown to Fig.11 (a)-(e). First, as shown in FIG. 11A, a mask blank in which a semi-transmissive film 52 and a light shielding film 53 are sequentially formed on a glass substrate 51 is prepared. On this mask blank, the positive resist for laser drawing is apply | coated, baking is performed, and the resist film 54 is formed. In addition, drawing data is pattern data corresponding to the pattern of the source / drain shown to Fig.3 (a).

Here, as a material of the light shielding film 53, it is preferable that a thin light and high light shielding property are obtained, for example, Cr, Si, W, Al, etc. are mentioned. Here, chromium was used. In addition, as the material of the semi-transmissive membrane 52, when the transmittance of the transmissive region is 100%, it is preferable that semi-transmittance of about 20% to 70% of the transmittance is obtained. For example, Cr compound (oxide of Cr, nitride) , Oxynitride, fluoride and the like), MoSi, Si, W, Al, and the like. Molybdenum silicide was used here. In addition, the film thickness of the translucent film 52 was adjusted so that the film transmittance T _f might be 44% at g line | wire.

Next, after laser drawing, it is developed and the resist pattern 54a corresponding to a light shielding area is formed on a mask blank as shown to FIG. 11 (b). Next, the light shielding film 53 is dry-etched using the formed resist pattern 54a as a mask to form a pattern 53a corresponding to the light shielding region as shown in Fig. 11C. At this time, except for the area | region corresponding to a light shielding area | region, the base semi-transmissive film 52 is exposed by the etching of the light shielding film 53. As shown in FIG. The remaining resist pattern 54a is removed using ashing with oxygen, concentrated sulfuric acid, or the like.

Next, the resist is applied to the entire surface again to form a resist film 54, and the second drawing is performed. The writing data at this time is pattern data including at least a translucent region corresponding to the channel portion between the source and the drain shown in Fig. 3A. After drawing, the resist film 54 is developed to form a resist pattern corresponding to at least the translucent region as shown in Fig. 11D. In this transfer pattern, the channel width was 3.7 µm in the pixel pattern and the peripheral circuit pattern.

Next, using the formed resist pattern 54 as a mask, the semi-transmissive film 52 of the area | region used as a light transmission area | region is removed by wet etching. As a result, as shown in Fig. 11E, the semi-transmissive region is partitioned into a transmissive region, thereby forming a translucent region and a translucent region. Here, although no resist pattern is formed on the pattern 53a of the light shielding film, in the present embodiment, the light shielding film 53 and the semi-transmissive film 52 of the mask blank to be used are formed of materials having different etching characteristics. In the environment where the semitransmissive film 52 is etched, the light shielding film 53 is hardly etched. At this time, the pattern 53a of the light shielding film becomes an etching mask (resist) so that the translucent film 52 is etched. However, in order to reliably prevent damage of the light shielding film 53, the resist pattern may be formed in a region including the pattern 53a of the light shielding film 53. In addition, the remaining resist pattern is removed by oxygen ashing or the like.

The multi-gradation photomask obtained in this manner is provided with a pattern of a light shielding film corresponding to the source and the drain of the pattern for the TFT substrate shown in Fig. 3A, and a pattern of a semi-transmissive film corresponding to the channel portion. The transparent substrate is exposed to form a transmissive region.

In addition, the semi-transmissive region (first pattern portion) of the pixel pattern region and the semi-transmissive region (second pattern portion) of the peripheral circuit pattern region were previously patterned so that the effective transmittance was equal to 37.2%. Using the above-mentioned multi-gradation photomask, the to-be-processed object to which the resist film was apply | coated actually was exposed using the exposure machine for large masks, and the resist film was developed after that, and the resist pattern was obtained. As for the exposure conditions, the NA (the number of apertures) of the exposure machine is 0.085, the sigma (coherency) is 0.9, the exposure wavelength is i-g line, and the intensity ratio is the same as that used in the above-described analysis. Was set to g / h / i = 1.0 / 0.8 / 0.95. In addition, the MoSi film was used as a semi-transmissive film which comprises a semi-transmissive area | region, and the composition and the film thickness were adjusted so that the light transmittance of this film might be 44% in g line | wire.

When the resist residual film value of the portion corresponding to the channel portion of the resist pattern was measured for each of the pixel pattern region and the peripheral circuit pattern region, there was a difference of 70 nm or more between the respective average values. Therefore, the change of the resist residual film value at the time of changing the exposure light quantity of an exposure machine was investigated and plotted, and the correlation shown in FIG. 6 was obtained. Thereafter, this was converted to obtain a correlation between the effective transmittance T _A shown in Table 5 and the resist residual film value. Using the obtained correlation, the effective transmittance T _A 40.6% (pixel pattern) and 38.6% (peripheral circuit pattern) of each of the pixel pattern and the peripheral circuit pattern corresponding to the desired resist residual film value: 600 nm were obtained.

Next, in order to achieve such effective transmittance T _A , the design adjustment of the pixel pattern and the peripheral circuit pattern was performed. Specifically, each line width (channel width) was changed. Since the correlation between channel width and effective transmittance T _A was grasped | ascertained in Table 1 previously, the pattern data of a mask was changed based on this. In other words, the channel portion of the pixel pattern region is larger than the channel portion of the peripheral circuit pattern region.

Thus, the same development process was performed on the to-be-processed object using the same exposure apparatus using the multi-gradation photomask after design change, and the part corresponding to the translucent area | region of all the pixel pattern area | region and the peripheral circuit pattern area | region The resist residual film value of was nearly 600 nm, and the difference of the average value was less than 20 nm.

As described above, in the multi-gradation photomask according to the present invention, the semi-transmissive region in the transfer pattern includes a first semi-transmissive portion having a first effective transmittance, and a second half having a second effective transmittance different from the first effective transmittance. By having a light-transmitting part, it becomes possible to precisely and precisely control the resist residual film value in the process of the to-be-processed object using a multi-gradation photomask.

This invention is not limited to the said embodiment, It can change suitably and can implement. For example, the material, the film structure, the pattern structure, the number of members, the size, the treatment procedure, and the like in the above embodiments are examples, and various modifications can be made within the range in which the effects of the present invention are exhibited. In addition, as long as it does not deviate from the range of the objective of this invention, it is possible to change suitably and to implement.

BRIEF DESCRIPTION OF THE DRAWINGS The figure which shows the light transmission curve of the semi-transmissive area | region in a photomask.

2 is a diagram showing an example of an apparatus for reproducing exposure conditions of an exposure machine.

(A) is a top view which shows a TFT pattern, (b) is sectional drawing along the IIIB-IIIB line | wire in (a) of FIG.

4 is an enlarged view of a light transmission curve shown in FIG. 1;

5 shows a relationship between channel width and effective transmittance.

6 is a diagram illustrating a relationship between an exposure amount and a resist residual film value.

7 is a diagram showing a relationship between an effective exposure amount and a resist residual film value.

8A to 8D are diagrams showing the film configuration of a multi-gradation photomask according to an embodiment of the present invention.

9A to 9D are diagrams showing the pattern configuration of a multi-gradation photomask according to an embodiment of the present invention.

Fig. 10 is a diagram showing a transfer pattern for manufacturing TFT for liquid crystal display device.

11 (a) to 11 (e) are diagrams for explaining the steps when forming the pattern shown in FIG.

<Explanation of symbols for the main parts of the drawings>

1: light source

2: irradiation optical system

3: photomask

3a: mask holder

4: objective lens system

7: aperture aperture

Claims (18)

delete delete delete delete delete delete delete delete delete delete A multi-gradation photo formed by patterning a light shielding film for shielding exposure light or a translucent film for partially transmitting the light shielding film and the exposure light formed on a transparent substrate, thereby forming a transfer pattern having a light transmission region, a light shielding region, and a semi-transmissive region As a manufacturing method of a mask, When the exposure light transmittance of the semi-transmissive region is referred to as an effective transmittance under exposure conditions used for exposure of the multi-gradation photomask, The semi-transmissive region has a first semi-transmissive portion having a first effective transmittance and a second semi-transmissive portion having a second effective transmittance, The first semi-transmissive portion and the second semi-transmissive portion is a method of manufacturing a multi-gradation photomask different from the first effective transmittance and the second effective transmittance by any one of the pattern line width or the membrane transmittance of the semi-transmissive film to be used is different. To Using a test mask, the correlation between the effective transmittance and the resist remaining film value in each of the first and second translucent parts is obtained. The first effective transmittance and the second effective transmittance corresponding to the resist resist film value of interest based on the correlation, respectively; The pattern line width, which is applied to the first semi-transmissive portion and the second semi-transmissive portion, so that the first semi-transmissive portion and the second semi-transmissive portion have the first effective transmittance and the second effective transmittance, respectively. It has a process of determining the membrane transmittance of the translucent film, The first semi-transmissive portion and the second semi-transmissive portion of the resist pattern formed by developing the resist film after transferring the transfer pattern by exposing to a resist film on a transfer object by using the photomask. And a portion corresponding to each other to form a multi-gradation photomask for forming the transfer pattern so as to have substantially the same resist remaining film value, The said substantially same resist residual film value is a manufacturing method of the multi-gradation photomask characterized by the difference of average value being less than 20 nm. 12. The method of claim 11, The first semi-transmissive portion and the second semi-transmissive portion manufacturing method of a multi-gradation photomask, characterized in that the line width is different from each other. 12. The method of claim 11, A method of manufacturing a multi-gradation photomask, wherein the first semi-transmissive portion and the second semi-transmissive portion are formed using semi-transmissive membranes having different film transmittances, respectively. 12. The method of claim 11, A method of manufacturing a multi-gradation photomask, wherein the first semitransmissive portion and the second semitransmissive portion having different film transmittances are formed using semitransmissive films having different laminated structures. 12. The method of claim 11, A method of manufacturing a multi-gradation photomask, wherein the first translucent portion and the second translucent portion having different film transmittances are formed by using translucent films having different film thicknesses, respectively. 12. The method of claim 11, The said multi-gradation photomask is a manufacturing method of the multi-gradation photomask characterized by the said semi-transmissive area being comprised by the fine pattern below a resolution limit. delete delete

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