JP7355598B2 - Photomask, electronic device manufacturing method, and photomask manufacturing method - Google Patents

Description

The present invention relates to a photomask, a method of manufacturing an electronic device, and a method of manufacturing a photomask.

2. Description of the Related Art In the production of electronic devices such as flat panel displays and semiconductor integrated circuits, a photomask having a transfer pattern formed by patterning an optical film such as a light shielding film on one main surface of a transparent substrate is used.

In particular, a halftone phase shift mask is known as a photomask for manufacturing semiconductor integrated circuits (hereinafter referred to as LSI: Large-scale Integrated Circuit). This photomask has a structure in which the light-shielding area in the binary mask has a transmittance that does not transfer the pattern, and the phase of the transmitted light is shifted by 180 degrees to improve resolution performance (non-patent technique). Reference 1).

On the other hand, as there has been a demand for image display devices with an increased number of pixels and even higher resolution, attempts have been made to use phase shift masks used in LSI manufacturing in the manufacturing of image display devices. (Patent Document 1).

Additionally, multi-gradation halftone masks used in the manufacture of flat panel displays are known. For example, a semi-transparent film pattern and a light-shielding film pattern with a transmittance of 20 to 50% and a phase difference of 60 to 90 degrees are provided on a transparent substrate. By using such a multi-gradation halftone mask, it is possible to form a photoresist pattern with a film thickness that varies depending on the position in a single exposure, reducing the number of lithography steps in the manufacturing process of flat panel displays. and reduce manufacturing costs. Halftone masks for such applications can achieve three gradations using a transparent substrate, a semi-transmissive film, and a light-shielding film, and can also create half-tone masks of four or more gradations using semi-transmissive films with multiple transmittances. It is also possible to realize a tone mask. (Patent Document 2).

Japanese Patent Application Publication No. 2014-092727 Japanese Patent Application Publication No. 2018-005072

Isao Tanabe, Yoichi Takehana, and Morihisa Homoto, “Key Technologies for Manufacturing Photomask Electronic Components,” 1st edition, Tokyo Denki University Press, April 20, 2011, p. 245-246

In the manufacturing process of flat panel displays, a proximity exposure method is sometimes applied. Although close-range exposure equipment does not have the same resolution performance as projection exposure equipment, it has a simpler equipment configuration because it does not include an imaging optical system between the photomask and the object to be transferred (display substrate, etc.). It is simple, relatively easy to introduce, and has high manufacturing cost advantages. For these reasons, the proximity exposure apparatus is mainly applied to manufacturing a black matrix or black stripe used in a color filter (CF) of a liquid crystal display device, or a photo spacer (PS). It can also be used as a black matrix for organic EL display devices.

On the other hand, due to demands for increased pixel density, increased brightness, and reduced power consumption of flat panel displays, there is a noticeable trend toward finer transfer patterns in photomasks used in manufacturing processes. If the projection exposure method is used to transfer fine patterns, resolution is advantageous, but the above advantages of close-up exposure are lost, so a new approach is to use the close-up exposure method to precisely transfer fine patterns. This is a serious issue.

The first aspect of the present invention is
A photomask for close exposure comprising a transfer pattern formed by patterning a transmission control film formed on a transparent substrate, the transfer pattern comprising a transmission control film formed on the transparent substrate. and a light transmitting part through which the transparent substrate is exposed, and the transmission control part has a phase shift amount of 255 degrees or more and less than 360 degrees with respect to the exposure light that exposes the photomask. It's a photomask.

The second aspect of the invention is
The transmission control section is the photomask of the first aspect, having a phase shift amount of 300 degrees or more and less than 360 degrees with respect to the exposure light .

The third aspect of the present invention is
When the photosensitive material on the transfer target to which the transfer pattern is transferred is a negative type, the transmission control section corresponds to a region where the photosensitive material is eluted by exposure using the photomask and development. and
When the transmittance of the transmission control section is T, and the threshold of light intensity at which the resist film on the transfer target becomes insoluble by development is Ith, the contrast defined as (Ith-T)/(Ith+T) is: The photomask according to the first or second aspect has a particle diameter of 0.667 or more .

The fourth aspect of the present invention is
This is a photomask according to the first or second aspect, which is for exposing a negative photosensitive material .

The fifth aspect of the present invention is
The exposure light is a photomask according to any one of the first to fourth aspects, including light having a wavelength of at least one of 313 nm, 334 nm, 365 nm, 405 nm, and 436 nm .

The sixth aspect of the present invention is
The transmission control section is a photomask according to any one of the first to fifth aspects , which has a transmittance of 10% or less for exposure light .

The seventh aspect of the present invention is
The transfer pattern is a photomask according to any one of the first to fifth aspects , having a line-shaped light-transmitting part with a width of 3 to 10 μm.

The eighth aspect of the present invention is
The transfer pattern is a photomask according to any one of the first to fifth aspects, which forms a line pattern with a width of 10 μm or less on a negative photosensitive material on a transfer target. .

The ninth aspect of the present invention is
Any of the first to fifth aspects, wherein the transfer pattern has a repeating pattern in which the transmission control portion and the transparent portion are regularly arranged, and a repeating pitch of the repeating pattern is 10 to 35 μm . It is one of the photo masks.

The tenth aspect of the present invention is
The transfer pattern has a repeating pattern in which the transmission control portion and the light transmission portion are regularly arranged, and the transmission control portion has a shape surrounded by a closed line. This is a photomask according to any one of the fifth aspects.

The eleventh aspect of the present invention is
The transfer pattern is a photomask according to any one of the first to fifth aspects, wherein the transfer pattern has a repeating pattern in which the transmission control portions are regularly arranged, and the transmission control portions are square . .

The twelfth aspect of the present invention is
The transmission control section is a photomask according to any one of the first to fifth aspects, which has a phase shift amount of 330 degrees or less with respect to exposure light.

The thirteenth aspect of the present invention is
The transfer pattern is a photomask according to any one of the first to fifth aspects, which is a pattern for forming a black matrix or a black stripe.

The fourteenth aspect of the present invention is
The photomask according to any one of the first to fifth aspects is characterized in that the transfer pattern is formed by patterning only the transmission control film on the transparent substrate.

The fifteenth aspect of the present invention is
preparing the photomask according to any one of the first to fifth aspects;
a transfer step of exposing the photomask using a proximity exposure device and transferring the transfer pattern to a negative photosensitive material film formed on the transfer target;
has
In the transfer step, the present invention is a method for manufacturing an electronic device for a flat panel display, in which proximity exposure with a proximity gap set in a range of 50 to 200 μm is applied.

The sixteenth aspect of the present invention is
A method for manufacturing a photomask for close exposure, comprising a transfer pattern formed by patterning a transmission control film formed on a transparent substrate, the method comprising:
preparing a photomask blank on which the transmission control film is formed on the transparent substrate;
a patterning step of patterning the transmission control film to form the transfer pattern;
has
The transfer pattern has a transmission control part in which the transmission control film is formed on the transparent substrate, and a light transmission part in which the transparent substrate is exposed,
The transmission control unit has a transmittance of 10% or less and a phase shift amount of 255 degrees or more and less than 360 degrees with respect to the exposure light that exposes the photomask.
This is a method for manufacturing a photomask.
The seventeenth aspect of the present invention is
When the photosensitive material on the transfer target to which the transfer pattern is transferred is a negative type, the transmission control section corresponds to a region where the photosensitive material is eluted by exposure using the photomask and development. and
When the transmittance of the transmission control section is T, and the threshold of light intensity at which the resist film on the transfer target becomes insoluble by development is Ith, the contrast defined as (Ith-T)/(Ith+T) is: This is a method for manufacturing a photomask according to a sixteenth aspect, in which the photomask is 0.667 or more.
The eighteenth aspect of the present invention is
The photomask according to the 16th or 17th aspect, wherein the exposure light includes light with a wavelength of at least one of 313 nm, 334 nm, 365 nm, 405 nm, and 436 nm.
The nineteenth aspect of the present invention is
A method of manufacturing an electronic device for a flat panel display, the method comprising:
A step of preparing a photomask by the manufacturing method according to any one of the sixteenth to eighteenth aspects;
a transfer step of exposing the photomask using a proximity exposure device and transferring the transfer pattern to a negative photosensitive material film formed on the transfer target;
has
In the transfer step, the present invention is a method for manufacturing an electronic device for a flat panel display, in which proximity exposure with a proximity gap set in a range of 50 to 200 μm is applied.

According to the present invention, it is possible to provide a photomask or the like for more accurately transferring a transfer pattern of a photomask using a proximity exposure device.

An example of a transfer pattern for forming a black matrix is shown. An explanatory cross-sectional view showing a state in which a black matrix is formed on a glass substrate constituting a transfer target. FIG. 2 is an explanatory diagram schematically illustrating the configuration of a proximity exposure apparatus. An example of the shape of a black matrix formed on a transfer target when the transfer pattern shown in FIG. 1 is assumed to be faithfully transferred onto the transfer target is illustrated. This figure shows a transferred image in which the shape is deteriorated due to the effects of light diffraction and interference when the binary mask having the transfer pattern shown in FIG. 1 is subjected to close exposure and transferred onto an object to be transferred. FIG. 2 is an explanatory diagram illustrating a photomask 10 and a transferred image formed by close exposure. For a transfer pattern with the shape shown in Figure 1 and the dimensions shown in Table 1, the influence on the transferred image when the proximity gap G is set to 100 μm and the amount of phase shift of the transmission control section is changed is calculated based on the numerical value of the difference S and the shape. This is shown by the distribution of differences. In the simulation, the results of examining fidelity when the proximity gap G is 150 μm are shown. FIG. 2 is an explanatory diagram illustrating a method of displaying simulation results. It is an explanatory diagram explaining a simulation result. It is an explanatory diagram explaining a simulation result. It is an explanatory diagram explaining a simulation result. The results of calculating the contrast Co of a transferred image formed on a transfer target are shown. Another example of a transfer pattern for forming a black matrix is shown. 14 shows the shape of a black matrix formed on a transfer target, assuming that the transfer pattern shown in FIG. 14 is faithfully transferred onto the transfer target. The results of an optical simulation similar to that performed in FIGS. 7 and 8 are shown for the case where the transfer pattern shown in FIG. 14 is subjected to close exposure. The results of an optical simulation similar to that performed in FIGS. 7 and 8 are shown for the case where the transfer pattern shown in FIG. 14 is subjected to close exposure. 12 is an explanatory diagram illustrating results of simulations similar to those in FIGS. 9 to 11. FIG. 12 is an explanatory diagram illustrating results of simulations similar to those in FIGS. 9 to 11. FIG. 12 is an explanatory diagram illustrating results of simulations similar to those in FIGS. 9 to 11. FIG. FIG. 2 is a schematic diagram showing how exposure light transmitted through a photomask during close exposure reaches an arbitrary point on a transfer target.

As the design of electronic devices such as flat panel displays becomes higher definition and density increases, it becomes inconvenient to simply miniaturize the transfer pattern of the photomask used to manufacture them. . For example, when a black matrix transfer pattern with a fine pattern width (CD: Critical Dimension) is exposed using the close exposure method, the pattern shape in the transferred image may become rounded, such as the corners of quadrilateral pixels becoming rounded. Deterioration is likely to occur.

FIG. 1 shows an example of a transfer pattern 35 for forming a black matrix. This transfer pattern 35 is formed on the transparent substrate 21 (see FIG. 6), and includes a transmission control section 36 and a light transmission section 37. The transparent portion 37 is a line-shaped portion where the surface of the transparent substrate 21 is exposed, and the transmission control portion 36 has a rectangular shape in which a transmission control film is formed on the transparent substrate 21. They are arranged in a matrix. That is, the transmission control section 36 having a shape surrounded by closed lines (here, a rectangle with four corners) passes through the transparent section 37 at regular intervals in the X direction and the Y direction perpendicular thereto. It is arranged in In addition to the case where the corner is a right angle as shown in FIG. 1, the corner may include an acute angle or an obtuse angle as shown in the embodiments described below.

By the way, in a conventional photomask, a region corresponding to the transmission control section 36 is formed as a light-shielding section in which a light-shielding film is formed on the transparent substrate 21, and when exposing the photomask, the region corresponding to the transmission control section 36 is formed as a light-shielding section, and substantially transmits exposure light when exposing the photomask. This was an area in which it was not possible to do so. In this case, as the pattern becomes finer and the CD becomes smaller, the shape of the transferred image obtained by transferring onto the transfer target 51 (see FIG. 3) by proximity exposure deteriorates, and the shape of the transfer pattern 35 is not faithfully reproduced. There was a tendency for it not to be reflected.

In FIG. 5, a conventional photomask consisting of a light-transmitting part and a light-blocking part is applied to a negative photosensitive material (hereinafter referred to as photosensitive material) provided on the surface of a transfer target 51 using a proximity exposure device 50 (see FIG. 3). The shape of the black matrix 52 obtained when the material is transferred to a material (also referred to as a resist for convenience) will be illustrated. This is an example of a case where faithful pattern transfer is not performed when the transfer pattern 35 shown in FIG. 1 is exposed. When compared with FIG. 1, the corners of the square are rounded, and the shape of the line-shaped portions is also changed.

This is because light diffraction occurs at the edge of the transfer pattern 35 during proximity exposure, and furthermore, due to the gap between the photomask and the transfer target 51 (i.e., the proximity gap), a complex image appears on the transfer target 51. This is thought to be due to light interference. That is, there is a problem that the light intensity distribution of transmitted light formed on the transfer target 51 does not faithfully reflect the transfer pattern 35 of the photomask. This tendency is particularly noticeable in high-definition patterns.

On the other hand, a so-called halftone phase shift mask, which has a light transmittance within a predetermined range for exposure light and shifts the phase of the exposure light by 180 degrees, instead of a light-shielding film, is used mainly for semiconductor devices to which projection exposure is applied. It is applied in the field of manufacturing masks (LSI masks). Therefore, by using this halftone type phase shift mask as a photomask for close exposure, it is possible to transfer the transfer pattern 35 more accurately. Therefore, we investigated how to improve pattern transferability when a phase shift film that shifts the phase of transmitted light by 180 degrees is formed in the transmission control section 36 in FIG. 1. However, as shown in the embodiments described below, the effect was not necessarily as expected.

Generally, it is known that Fresnel diffraction acts on the principle of forming a transferred image by proximity exposure. FIG. 21 is a schematic diagram showing how exposure light transmitted through the photomask 10 in close exposure reaches an arbitrary point on the transfer target 51. In FIG. 21, light waves are represented by periodic structures of solid lines and broken lines. The solid lines indicate the crests of the waves, and the dashed lines indicate the troughs of the waves (the crests and troughs may also be reversed). It can be seen that the light transmitted through the slit SL (Slit) travels while causing diffraction (turnaround) at the edges, and reaches the destination on the transfer target 51 at various phases.

The amplitude information U (x, y) of light at any one point (x, y) of the arrival point is approximated by the following Fresnel diffraction equation (1) (J.W. Goodman, Introduction to Fourier Optics (3rd Edition), Roberts & Company Publishers (2016), p. 66-67).

In Fresnel diffraction equation (1), ξ and η represent the X and Y coordinates on the photomask 10, respectively. That is, U (ξ, η) is the amplitude information of light at the coordinates (ξ, η) on the photomask 10. Further, z represents a proximity gap, λ represents a wavelength of exposure light, k represents a wave number, and j represents an imaginary number unit, respectively.

Then, the integration of the amplitude information U(x, y) at all positions within a predetermined plane on the transfer object 51 determines the light intensity distribution of the transferred image, which is transferred onto the transfer object 51. .

On the other hand, in order to improve the resolution and fidelity of the transferred image formed when the transfer pattern 35 of the photomask 10 is subjected to close exposure, the phase and amplitude of the light on the transfer target 51 should be optimized. This is considered to be useful. This may potentially create a more advantageous light intensity distribution for Fresnel diffraction that occurs in existing binary masks.

According to the inventor's study, when considering the above, it was found that the phase shift amount (180 degrees) of the halftone phase shift mask used in projection exposure is not necessarily optimal for close exposure. Ta.

As a result of the study, we decided to form the transfer pattern 35 for close exposure (for example, the transmission control section 36 in FIG. 1) with a transmission control film that has a phase shift effect, and to change the amount of phase shift from that of the existing halftone. It has been found that when the size of the phase shift mask is larger than that of the phase shift mask, deterioration in the shape of the transferred image obtained on the transfer target 51 can be reduced and the fidelity of transfer can be improved.

[Embodiment 1]
The photomask 10 of this embodiment is configured by providing a predetermined transfer pattern 35 on one main surface of a plate-shaped transparent substrate 21 whose main surface is rectangular or square. The transparent substrate 21 is made of a transparent material such as synthetic quartz, processed and polished to have a flat and smooth main surface. As the transparent substrate 21 used in a photomask for a flat panel display, one whose main surface has a short side of 300 to 2000 mm and a thickness of 5 to 16 mm is suitably used.

The transfer pattern 35 of the photomask 10 is illustrated in FIG. The transfer pattern 35 includes a transmission control section 36 in which a transmission control film is formed on the transparent substrate 21, and a light transmission section 37 in which the transparent substrate 21 is exposed.

Here, the transmission control section 36 is a rectangle with a short side dimension B and a long side dimension C, and is arranged in a matrix with an interval D in the short side direction and an interval E in the long side direction. There is. That is, the respective transmission control parts 36 are arranged regularly through the light transmission part 37, and the pitch Pm1 (also referred to as longitudinal pitch) in the long side direction is Pm1 (=C+E), and the pitch Pm2 ( The pattern is a repeating pattern in which the short pitch (also referred to as short pitch) is Pm2 (=B+D). In this embodiment, the transfer pattern 35 is a pattern for a black matrix 52 (see FIG. 4) used in a flat panel display, and the transparent portions 37 extending vertically and horizontally in FIG. The black matrix 52 is transferred to a mold photosensitive material and becomes the desired black matrix 52. FIG. 2 shows an explanatory cross-sectional view of a state in which a black matrix 52 is formed on a glass substrate 56 constituting a transfer target 51. As shown in FIG.

That is, the photomask 10 is a two-tone photomask that forms a portion where the photosensitive material remains and a portion where the photosensitive material does not remain on the transfer target, and the transmission control section 36 corresponds to the light blocking section of a conventional binary mask. do.

The dimensions (CD) of each portion of the transfer pattern 35 are preferably as follows, for example. In FIG. 1, the width D of the vertical linear transparent portion 37 (also referred to as a longitudinal slit) is
3≦D≦10 (μm)
It is preferable that it is, more preferably,
3≦D≦8 (μm)
More preferably 3≦D≦6 (μm)
It is. As a result of the above, a good black matrix 52 with a high aperture ratio can be obtained in a flat panel display. When the present invention is applied even to a high-definition pattern having such a fine CD, shape deterioration is reduced and the effect is significant.

Further, in FIG. 1, the width E of the line-shaped transparent portion 37 (also referred to as a short slit) extending in the horizontal direction may be equal to or larger than the width D of the long slit.
For example, 3≦E≦30 (μm)
It may be.

In addition, the shorter pitch (repetition pitch) Pm2 of the repetition pattern in FIG.
10≦Pm2≦35 (μm)
It can be done.
More preferably,
15≦Pm2≦35 (μm)
It can be done. At this level, it can be appropriately used for high-definition displays of about 250 ppi to 700 ppi.

On the other hand, the longitudinal pitch Pm1 is preferably larger than the above Pm2. for example,
30≦Pm1≦105

In the close exposure, the projection magnification is not set (that is, the same magnification), and the longitudinal pitch Pp1 and the transverse pitch Pp2 on the transfer target 51 are the same as Pm1 and Pm2 described above.

Further, when performing proximity exposure using such a transfer pattern 35, the proximity gap G is preferably about 50 to 200 μm. According to the present invention, even when there is in-plane non-uniformity of the proximity gap G, the in-plane non-uniformity of the transferred image caused thereby is reduced. The collimation angle for close exposure is preferably about 1.5 to 2.5 degrees.

Consider forming a linear pattern with a width of 10 μm or less on the transfer target 51 using the transfer pattern 35 as described above, corresponding to the linear transparent portion 37 with the width D. For example, consider forming a pattern with a width of 3 to 10 μm, more finely, 3 to 8 μm, or even 3 to 6 μm to form the black matrix 52 with a fine width.

In the photomask 10 of this embodiment, the transmission control film for forming the transmission control portion 36 has the effect of shifting the phase of the exposure light that exposes the photomask 10 by φ (degrees). In other words, the phase shift amount φ of the transmission control film is
φ>180 (degree)
It is.

Note that φ>180, that is, the phase shift amount exceeding 180 degrees represents the range of the phase shift amount φ defined by the following equation (2). (2) In the formula, M represents a non-negative integer.
180+360M<φ<360+360M (degrees) ‥‥‥ (2)

Here, the exposure light for exposing the photomask 10 is light used to expose and transfer the transfer pattern 35 by the proximity exposure device 50, and light having a wavelength within the range of 313 to 365 nm is preferably used. It will be done. For exposure light including a plurality of wavelengths, any wavelength (preferably a wavelength having an intensity peak) included in the above wavelength range can be used as a reference wavelength for the phase shift amount φ.

For example, when using exposure light including a wavelength within the range of 313 to 365 nm, 313 nm on the short wavelength side may be used as the representative wavelength, or 334 nm, which is close to the median of the wavelength range, may be used as the representative wavelength. Further, 365 nm, which is on the longest side of the wavelength range described above, can be set as the representative wavelength.

Furthermore, when the exposure light includes a plurality of wavelengths, φ>180 can be satisfied for all wavelengths included in the above wavelength range. The same also applies to the preferred wavelength ranges described below.

Therefore, for example, the photomask 10 is for close exposure using exposure light having a wavelength within the wavelength range of 313 to 365 nm, and the transmission control section 36 has a wavelength of 365 nm on the longest wavelength side. The photomask 10 can have a phase shift amount of more than 180 degrees with respect to the light. In this case, the amount of phase shift of the transmission control section 36 exceeds 180 degrees for substantially all wavelengths in the above wavelength range included in the exposure light.

Alternatively, when the wavelength of the exposure light includes 365 to 436 nm (i-line, h-line, g-line), the longest wavelength of 436 nm is taken as the representative wavelength, and the phase shift amount φ of the transmission control film with respect to this is set as the representative wavelength. may be set to φ>180. Furthermore, the representative wavelength may be the wavelength with the highest intensity in the wavelength range of the exposure light used.

Further, the transmission control film for forming the transmission control section 36 has a transmittance T with respect to exposure light. This transmittance T is a value when the transparent substrate 21 is 1.0 (100%). Moreover, the transmittance here can be set to the same representative wavelength as that described regarding the amount of phase shift.

The transmittance T is preferably 0.1 (10%) or less. For example, the transmittance T is
0.01≦T≦0.1
It can be done. If T is too small, the effect of improving fidelity, which will be described later, cannot be achieved significantly with respect to existing binary masks. If T is too large, there is a risk that the light-shielding property will be insufficient in a region of the transmission control section 36 that is far from the edge.

Details of the transmittance T and phase shift amount φ of the transmission control film will be described later.

When forming the black matrix 52 of a flat panel display using the photomask 10, in FIG. 1, two-dot chain lines indicate lines corresponding to boundaries between pixels constituting the flat panel display. In this example, one pixel is a square that includes a total of three sub-pixels of red, green, and blue, and has a side length of A (=Pm1). One sub-pixel is formed in each portion corresponding to the transmission control section 36 in FIG.

When the flat panel display is a liquid crystal display, it is manufactured by sealing liquid crystal between a color filter substrate and a TFT (Thin-Film-Transistor) substrate, which are arranged to face each other. The black matrix 52 is formed on one surface of the color filter substrate. For example, red, green, and blue color filters can be formed in a portion corresponding to the transmission control section 36 in FIG. 1.

When the flat panel display is an organic EL (electro-luminescence) display, red, green, and blue organic EL light emitting elements are formed in the portion where the transmission control section 36 in FIG. 1 is provided.

In either case, the black matrix 52 prevents color mixing between subpixels and light leakage, and makes images and videos displayed on a flat panel display clear. In order to achieve high definition, that is, a bright flat panel display with small individual pixels and high pixel density, the width of the black matrix 52 is made thin (for example, 3 to 10 μm, more preferably 3 to 8 μm). In addition, it is necessary to form it into a designed shape.

Therefore, it is desired that the shape of the transfer pattern 35 of the photomask 10 be reflected in the transferred image on the transfer target 51 as faithfully as possible (with high fidelity). Here, fidelity refers to the degree to which the shape of the transfer pattern 35 of the photomask 10 is maintained on the transfer target 51. For example, the corner of the transfer pattern 35 is the transferred image on the transfer target 51. Fidelity can be said to have improved when the extent to which rounding occurs in the transferred image is reduced, or the extent to which the line-shaped portion of the transfer pattern 35 becomes thicker or thinner in the transferred image is reduced.

As described above, in the transfer pattern 35, the transmission control section 36 surrounded by a closed line is arranged through the linear light transmission section 37. Due to this transmission control section 36, the photosensitive material on the transfer target 51 is eluted by exposure using the photomask 10 and development, and on the other hand, the portion corresponding to the transparent section 37 surrounding this is covered with the photosensitive material. A three-dimensional construct (for example a black matrix) is formed. The photomask 10 of the present invention has an excellent effect on improving the shape fidelity of this three-dimensional structure.

In the following, a case where A to E shown in FIG. 1 have the lengths shown in Table 1 will be explained as an example.

The proximity exposure device 50 is preferably used for exposing the photomask 10 of the present invention. FIG. 3 is an explanatory diagram schematically illustrating the configuration of the proximity exposure apparatus 50. The proximity exposure device 50 irradiates light emitted from a light source 57 onto the back surface 12 of the photomask 10 via an illumination system 58 . The irradiated light is transmitted to the surface 11 side on which the transfer pattern is formed, and reaches the transfer target 51. A proximity gap G is provided between the photomask 10 and the transferred object 51.

Light source 57 can be a high pressure mercury lamp. A high-pressure mercury lamp has strong peaks at the i-line, h-line, and g-line, but for exposure of the photomask 10 of this embodiment, the i-line (wavelength λ = 365 nm) and the shorter wavelength side are used. Preferably, spectral groups are used. For example, it is useful to use a negative resist that has a good sensitivity range for exposure light having peaks of 365 nm, 334 nm, and 313 nm.

FIG. 4 illustrates the shape of the black matrix 52 formed on the transfer target 51, assuming that the transfer pattern 35 shown in FIG. 1 is faithfully transferred onto the transfer target 51. When a negative photosensitive material is used, black and white are reversed with respect to FIG. Here, the shape shown in FIG. 4 is assumed to be a black matrix in an ideal state.

On the other hand, FIG. 5 shows a case where the binary mask having the transfer pattern 35 shown in FIG. Show the image. For example, in a conventional photomask in which the transmission control section 36 shown in FIG. 1 is a light shielding section, such shape deterioration is likely to occur. In this case, the fidelity of transfer is insufficient, such as the corners of portions corresponding to sub-pixels being rounded.

Therefore, in the transfer pattern 35 shown in FIG. 1, when the transmission control film used in the transmission control section 36 has a predetermined transmittance T and phase shift amount φ, how does the fidelity of the transferred image change? We verified this by optical simulation using Fresnel diffraction.

That is, when the transfer pattern 35 is exposed by close exposure, the light intensity distribution of the exposure light formed on the transfer target 51 is determined by optical simulation, and better transfer conditions are found and the transmission of the transmission control film is determined. The influence of the ratio T and the amount of phase shift φ on the transferred image was examined.

The photomask 10 and a transferred image formed by close exposure will be explained using FIG. 6. FIG. 6A shows a schematic cross-sectional view of the photomask 10 taken along the short side direction of the transmission control section 36. As explained using FIG. 1, the width of the transmission control section 36 is B, and the width of the light transmission section 37 is D. Here, the dimension D corresponding to the width of the black matrix 52 is a fine dimension of 10 μm or less.

FIG. 6B shows the light intensity distribution formed on the transfer target 51 when the photomask 10 is exposed from the back surface side by the proximity exposure device 50. The horizontal axis indicates the position on the transfer target 51, and the vertical axis indicates the light intensity.

The light intensity Ith corresponds to the threshold of light intensity when forming the black matrix 52 of width D on the negative photosensitive material on the transfer target 51 by development. At this time, when considering an ideal development model in which the development behavior can be binarized into completely soluble and completely insoluble, Ith is the threshold of light intensity at which the negative photosensitive material becomes completely insoluble.

In a repetitive pattern such as a line and space pattern in which brightness and darkness are repeated alternately, the quality of the transferred image is generally evaluated by an index called contrast. The higher the contrast value, the clearer the difference in light intensity between bright and dark areas. Since photolithography is a method of printing transfer information onto the transfer target 51 using this difference in brightness, it is preferable to have a contrast of a certain value or more.

There are several methods for quantifying contrast, but quantification using Michelson Contrast is widely used as a method that focuses on differences. Michelson Contrast is defined as {(I1-I2)/((I1+I2)}, where the light intensity in the bright area is I1 and the light intensity in the dark area is I2.In the present invention, the light intensity in the bright area is Ith has already been defined as an index representing the dark area.On the other hand, it is clear from FIG. 6(b) that the dark area is largely controlled by the properties of the transmission control section 36.In FIG. The figure shows a case where I2 is close to 0, assuming a sufficiently dark case, but if the transmission control film has a significant transmittance T, as will be described later, this dark area will not be placed on the photomask. Depending on the position where the light is applied or the position where it acts on the transferred object, the light intensity may behave as non-negligible.

Based on the above, here, the contrast Co in this embodiment is defined by equation (3), and the influence of the transmittance T of the transmission control unit 36 and the amount of phase shift φ on the light intensity distribution is investigated.

Here, Ith corresponds to the threshold of light intensity at which the resist film on the transfer target 51 becomes insoluble by development, as described above. It is assumed that a transfer image having a width D is formed on the transfer target 51.

T is a film transmittance specific to the transmission control film with respect to the exposure light of the transmission control section 36 without considering phase effects, and is a value where T is 1 when the transmittance is 100%.

In equation (3), the contrast Co represents the Michelson contrast between Ith and T. That is, when the value of T has a sufficient proportion that cannot be ignored with respect to Ith, the numerator becomes relatively small with respect to the denominator, and the contrast Co also becomes small. At this time, in addition to the expected fidelity improvement effect, the following concerns can be expected to arise.

When the resist is of a negative type, a crosslinking reaction proceeds upon irradiation with exposure light, resulting in a state in which it does not dissolve out during development.

Excluding ideal models, actual photosensitive materials have more or less unreliable photoreactions and, as a result, unreliable development behavior. As a result, the crosslinking reaction proceeds partially on the transfer target 51 in areas where a resist structure is ultimately unnecessary (for example, in areas where the black matrix 52 should not be formed), and residue remains after development. Possible risks. That is, if the value of the transmittance T is close to Ith, the risk of crosslinking reaction in areas where the above-mentioned structure is unnecessary and, ultimately, residue retention may increase. In order to avoid this, it is desirable that the transmittance T of the transmission control section 36 is within a range that does not exceed 20% of the light intensity threshold Ith due to exposure. The contrast C2 when the transmittance T is 20% of the light intensity threshold Ith due to exposure is calculated by equation (4).

That is, the contrast is preferably 0.667 or more.

Furthermore, considering the possibility of variations occurring in the exposure process and the subsequent development process (variations in irradiation intensity, in-plane non-uniformity of development, etc.), in order to obtain a better yield, it is necessary to It is more desirable that the transmittance T is 10% or less of the exposure threshold Ith. The contrast C1 when the transmittance T is 10% of the exposure amount threshold Ith is calculated by equation (5).

That is, it is more desirable that the contrast is 0.818 or more. As is clear from the above equations (4) and (5), these preferable contrast values do not depend on the value of Ith.

Furthermore, in order to more directly evaluate the degree to which the transfer pattern 35 formed on the photomask 10 is reflected on the transfer target 51 (fidelity), a simulation was conducted to determine how the transfer pattern 35 formed on the photomask 10 is formed on the transfer target 51 by close exposure. A transferred image of the transferred pattern 35 is obtained, and the shape difference between the obtained transferred image and the transferred pattern 35 is quantified and calculated as a difference S.

The difference S corresponds to the area where the shape of the transfer pattern 35 on the photomask 10 and the shape of the transferred image formed on the transfer target 51 differ. The difference S is defined by equation (6). The closer the difference S is to 0, the more faithfully the pattern on the photomask 10 is transferred to the transfer target 51, which is a state of good so-called fidelity.

S=S1+S2 (6)
Here, S1 becomes a region that constitutes the black matrix 52 if the transfer pattern 35 of the photomask 10 is faithfully transferred, but in the transferred image obtained by simulation, the light intensity reaches the exposure amount threshold Ith. This means the area that does not constitute the black matrix 52.

On the other hand, S2 is an area that does not constitute the black matrix 52 if the transfer pattern 35 of the photomask 10 is faithfully transferred, but in the transferred image obtained by simulation, the light intensity exceeds the threshold value Ith, and the black matrix 52.

That is, S1 and S2 can be considered as the absolute values of errors (deviations) on the minus side and plus side, respectively, from faithful transcription, and their sum is evaluated here. Note that the numerical values of S1 and S2 were quantified by calculating the number of pixels in the deviation portion when outputting to 680 pixels square, and multiplying this by u, which is the pixel unit area.

FIG. 7 shows the influence on the transferred image when the proximity gap G is 100 μm and the phase shift amount of the transmission control unit 36 is changed for the transfer pattern 35 having the shape shown in FIG. 1 and the dimensions shown in Table 1. The numerical value of the difference S and the distribution of the shape difference (FIGS. 7(b) to (f)) are shown by simulation. Specifically, in addition to Comparative Example 1 of a binary mask with a transmittance of zero, the transmittance of the transmission control unit 36 is set to 0.03 (3%), and the phase shift amount of the transmission control unit 36 is set to 0, 90, The difference S for each case of 180 degrees and 270 degrees and the distribution of shape differences corresponding to the difference S are calculated. Note that Ith here was set so that a portion of the transfer target 51 corresponding to the narrow black matrix 52 (a portion corresponding to the width D of the light-transmitting portion 37 in FIG. 1) was 6 μm.

Looking at the distribution of the shape difference for calculating the above-mentioned S and the numerical value of S obtained by quantifying it with respect to the shape (a) of the transfer pattern 35, the following can be seen. For Comparative Example 1 in (b) (binary mask, hereinafter also simply referred to as "binary") and Reference Example 1 in (c) (halftone mask without phase shift, hereinafter also referred to as "HTM without phase difference") , Example 1 (f) in which the phase shift amount is larger than 180 degrees has the lowest numerical value of the difference S and is excellent in fidelity.

Reference example 3 shown in (e) in which a so-called halftone type phase shift mask (hereinafter also referred to as "180 degree PSM") with a phase shift amount of 180 degrees is used as the transmission control section 36 is the comparative example shown in (b). The fidelity was lower than the binary mask of 1.

The above tendency can also be visually grasped from the distribution of shape differences in FIG. In other words, the photomask 10 of this embodiment is capable of obtaining a transferred image superior to any conventional photomask by setting the amount of phase shift of the transmission control section 36 to a value exceeding 180 degrees. But it became clear.

Generally, the proximity exposure method is performed by setting the proximity gap to a predetermined value (for example, 100 μm), but it is not practical to set the distance to the transferred object 51 to this value over the entire surface of the photomask 10. It is impossible. For example, in the photomask 10 for a large-sized flat panel display, the proximity gap may be different between the center of the photomask 10 and the outer edge of the photomask 10 because it bends due to its own weight during close exposure. Alternatively, a more complicated in-plane distribution (dispersion) of the proximity gap may occur due to a holding mechanism that applies a load to the photomask 10 in order to reduce this deflection.

Therefore, in the above simulation, the fidelity was examined when the proximity gap G was 150 μm, and the results are shown in FIG. In this case, since the proximity gap of 150 μm is unintentionally caused due to in-plane distribution, etc., the exposure threshold value is the value of Ith derived at 100 μm, which is the predetermined proximity gap value intentionally set. Use.

According to FIG. 8, similar to FIG. 7, the difference in shape is smaller in the photomask 10 of Example 2 shown in (f) compared to the binary mask shown in (b) and the 180 degree PSM shown in (e). , showing excellent fidelity.

From the above, when applying a phase shift film to the photomask 10 for close exposure to improve resolution due to the phase shift effect, the amount of phase shift is established in the projection exposure method. It has become clear that a 180 degree phase shift is not necessarily optimal. That is, it has been found that the phase shift effect used in the proximity exposure method exhibits better fidelity when the amount of phase shift exceeds 180 degrees. Particularly, in this case, it was found that the shape stability of the transferred image was outstandingly excellent against fluctuations in the proximity gap G. This point can also be understood from the fact that the difference between Example 1 and Example 2 (that is, the difference in the difference S between FIG. 7(f) and FIG. 8(f)) is small.

Next, a more detailed optical simulation regarding the fidelity of the obtained transferred image will be shown.

In the following optical simulation, when the phase shift amount φ and the transmittance T change in the transfer pattern 35 of FIG. The correlation between Co and the difference S was investigated.

FIG. 9 is an explanatory diagram illustrating a method of displaying simulation results. The simulation is performed by changing various combinations of the phase shift amount φ of the transmission control unit 36 and the transmittance T. In FIG. 9, the horizontal axis shows the phase shift amount φ (degrees), and the vertical axis shows the transmittance T. Each rectangular frame whose boundary is indicated by a broken line indicates each simulation condition.

A section K surrounded by a thick frame indicates a binary mask in which the transmittance T of the transmission control section 36 is 0, that is, the transmission control section 36 does not transmit light. The L portion surrounded by a thick frame indicates an HTM in which the phase shift amount φ of the transmission control unit 36 is 360 degrees, that is, 0 degrees, and there is no phase difference. The M section surrounded by a thick frame indicates 180 degree PSM. The N section surrounded by a thick frame indicates the transmission control section 36 in which the phase shift amount φ exceeds 180 degrees and is less than 360 degrees. In the following description, the photomask 10 including the transmission control section 36 corresponding to the N section will also be referred to as an overshift angle phase shift mask.

In the simulation, exposure conditions were applied to a broad wavelength range including light having wavelengths of 313 nm, 334 nm, and 365 nm (intensity ratio 0.25:0.25:0.5). These are main peak components of the i-line and below that are suitable for the photosensitive region of a negative resist, which is applied to the manufacture of the black matrix 52 and the like, in the radiation spectrum of the high-pressure mercury lamp. The transmittance T and the phase difference φ match predetermined values for each wavelength due to simulator characteristics. Further, the proximity gap G was set to 100 μm.

Further, the transfer pattern 35 of the photomask 10 is the same as that described with reference to FIG.

In this simulation, the values of the contrast Co and the difference S under each of the above simulation conditions were calculated and associated with each rectangular frame indicated by the broken line in FIG.

FIGS. 10 to 12 are explanatory diagrams illustrating simulation results. FIG. 10 shows the case where the proximity gap G is 100 μm, and the part surrounded by the thick line shows that the difference S due to the overshift angle phase shift mask is HTM with no phase difference having the same transmittance (0.03), It shows a region that is smaller compared to 180 degree PSM and smaller than binary.

That is, the region within the bold line is a region in which the transfer fidelity of the overshift angle phase shift mask is superior to that of binary, HTM without phase difference, and 180 degree PSM.

FIG. 11 shows the results of a simulation conducted under the same conditions as FIG. 10, except that the proximity gap G was 150 μm. The part surrounded by a thick line indicates a region in which the fidelity of the overshift angle phase shift mask is superior to any of the binary, HTM without phase difference, and 180 degree PSM based on the same criteria as above.

Generally, when the proximity gap G becomes larger than a set value, the deterioration of the transferred image tends to become significant. This point can also be understood from FIGS. 7 and 8. However, according to the overshift angle phase shift mask of the present invention, even if the proximity gap G changes within the plane and becomes larger than the set value, compared to existing photomasks, it is possible to achieve high transfer with stable fidelity. It can be seen that it shows gender.

The area surrounded by the dashed line in FIG. 12 represents the union of the parts surrounded by the bold lines in FIGS. 10 and 11. That is, when the proximity gap G is either 100 μm or 150 μm, this indicates a region where the fidelity of the overshift angle phase shift mask is higher than that of the other photomasks 10. Further, the portion surrounded by a thick line indicates the portion surrounded by a thick line in both FIGS. 10 and 11, that is, a common set. That is, both cases in which the proximity gap G is 100 μm and 150 μm indicate a region where the fidelity of the overshift angle phase shift mask is high.

From FIG. 12, it can be seen that the overshift angle phase shift mask in which the phase shift amount φ of the transmission control unit 36 exceeds 180 degrees has more advantageous fidelity than the existing photomask.

Further, according to FIG. 10, it can be seen that when the phase shift amount φ of the transmission control section 36 is 255 degrees or more, the fidelity at this proximity gap G is advantageous.

Furthermore, according to FIG. 10, when the transmittance T of the transmission control section 36 is 0.06 or less, the selection range of the phase shift amount φ of the transmission control section 36 for obtaining good fidelity is wide.

Furthermore, according to FIG. 11, even if the proximity gap unintentionally widens due to in-plane distribution, etc., good fidelity can be achieved in a wide overshift angle range in which the phase shift amount φ of the transmission control unit 36 is 330 degrees or less. can get.

Further, according to FIGS. 10 to 12, when the phase shift amount φ of the transmission control unit 36 is 255 degrees or more and 330 degrees or less, there is an advantage that the fidelity is less affected by fluctuations in the proximity gap G, and Sometimes the benefits are more pronounced.

Further, if the transmittance T is set to 0.06 or less, there is a wide selection range of the phase shift amount φ in order to obtain advantageous fidelity regardless of fluctuations in the proximity gap G.

Furthermore, if the phase shift amount φ of the overshift angle phase shift mask is set to 270 degrees or more, the selection range of the transmittance T for obtaining advantageous fidelity is wide.

Note that FIG. 13 shows the results of calculating the contrast Co of the transferred image formed on the transfer target 51. The W part surrounded by a thick frame is an area where the contrast Co is 0.667 or more (but less than 0.818), and the V part surrounded by a thick frame is an area where the contrast Co is 0.818 or more. It is. That is, the region W is a preferable range according to the above formula (4), and the region V is a more preferable range according to the above formula (5).

Therefore, in addition to the preferable phase shift amount φ and transmittance T conditions for obtaining the above-mentioned advantageous fidelity, by also considering the advantageous range of contrast Co shown in FIG. 13, more preferable transferability can be obtained. You can see what you can get.

For example, in an overshift angle phase shift mask, when the phase shift amount φ of the transmission control unit 36 is 225 degrees or more, the range of applicable transmittance T for obtaining a transferred image with good contrast is expanded, and the phase shift amount φ is It can be seen that when the value is set to 270 or more, an even wider range of advantageous effects can be obtained.

Further, as mentioned above, the value of the transmittance T is preferably 0.1 or less, but in particular,
0.01≦T≦0.09
With this, a transferred image with good contrast can be obtained over a wide range of the phase shift amount φ of the transmission control unit 36.
0.01≦T≦0.08
If so, the benefits are even more pronounced.

Furthermore,
T≦0.05
If so, a more preferable contrast Co can be obtained,
T≦0.04
If so, the selection range of the phase shift amount φ of the transmission control unit 36 is high in order to obtain a preferable contrast.

[Embodiment 2]
FIG. 14 shows a case where the design shape of the transfer pattern 35 of the photomask 10 is changed from the first embodiment. That is, the transfer pattern 35 of this photomask 10 has a repeating parallelogram pattern instead of a rectangle. For example, a design is assumed in which the shape of a subpixel of a flat panel display is a parallelogram.

In FIG. 14, the transmission control section 36 is a parallelogram with a base length of C, a height of B, an acute angle of 45 degrees, and an obtuse angle of 135 degrees. The transmission control units 36 are arranged in a matrix with an interval D in the height direction and an interval E in the direction along the bottom side. The transfer pattern 35 of this embodiment is the same as that of Embodiment 1 except for the design changes of these patterns unless otherwise specified, and the dimensions A to E here are the same as the dimensions shown in Table 1. shall be.

FIG. 15 shows the shape of the black matrix 52 formed on the transfer target 51, assuming that the transfer pattern 35 shown in FIG. 14 is faithfully transferred onto the transfer target 51. This is assumed to be the black matrix 52 in an ideal state. However, when the transfer pattern 35 in FIG. 14 is actually subjected to close exposure, the transferred image on the transfer target 51 suffers shape deterioration due to light diffraction and interference.

Here, the results of optical simulations similar to those performed in FIGS. 7 and 8 above are shown in FIGS. 16 and 17 when the transfer pattern 35 shown in FIG. 14 is subjected to close exposure.

That is, regarding the transfer pattern 35 in FIG. 14, the transferred image and the difference S when changing the phase shift amount of the transmission control section 36 with D set to 6 μm and proximity gap G set to 100 μm are shown in FIG. 16(b). ) to (e). Specifically, in addition to Comparative Example 4 of a binary mask with a transmittance of zero, the transmittance of the transmission control unit 36 is set to 0.03 (3%), and the phase shift amount of the transmission control unit 36 is set to 0, 90, The difference S for each case of 180 degrees and 270 degrees is calculated. In this case as well, the light intensity was standardized so that the narrow black matrix 52 (the portion corresponding to D of the transfer pattern 35) was 6 μm. The collimation angle for close exposure was 2.0 degrees. The simulation conditions were the same as in the first embodiment.

Furthermore, FIG. 17 shows the results of simulation under the same conditions as FIG. 16 except that the proximity gap G is 150 μm.

According to FIGS. 16 and 17, it can be seen that the transfer fidelity of the overshift angle phase shift masks of Example 3 and Example 4 is superior based on the value of the difference S compared to the binary mask and 180 degree PSM. . Furthermore, according to FIG. 16, when the proximity gap G is 100 μm, the fidelity of HTM without phase difference is slightly better than that in Example 3, but according to FIG. 17, when the proximity gap G is 150 μm, the The numerical value of the difference S in Example 4 is better. Furthermore, it can be understood from Examples 3 and 4 that when a proximity gap G that differs depending on the in-plane position is formed in proximity exposure, the amount of change in the difference S is small due to the variation in the proximity gap G. This point is extremely significant, especially in the manufacture of flat panel displays, in terms of maintaining the in-plane uniformity of the transferred pattern.

FIGS. 18 to 20 are explanatory diagrams illustrating the results of simulations similar to those shown in FIGS. 9 to 11 above.

Figure 18 shows the case where the proximity gap G is 100 μm, and the part surrounded by a thick line shows that the fidelity of the overshift angle phase shift mask is superior to that of binary, HTM without phase difference, and 180 degree PSM. Indicates the area.
That is, the region within the bold line is a region in which the above-mentioned difference S in the overshift angle phase shift mask is smaller than the binary one, and further smaller than either the HTM without phase difference or the 180 degree PSM having the same transmittance.

FIG. 19 shows the results of a simulation conducted under the same conditions as FIG. 18 except that the proximity gap G was 150 μm. The part surrounded by a thick line indicates a region in which the fidelity of the overshift angle phase shift mask is superior to any of binary, HTM without phase difference, and 180 degree PSM.

The area surrounded by a dashed line in FIG. 20 indicates the union of the parts surrounded by thick lines in FIGS. 18 and 19. That is, when the proximity gap G is either 100 μm or 150 μm, it indicates a region where the overshift angle phase shift mask has high fidelity. Further, the portion surrounded by a thick line indicates the portion surrounded by a thick line in both FIGS. 18 and 19, that is, a common set. That is, both cases in which the proximity gap G is 100 μm and 150 μm indicate a region where the fidelity of the overshift angle phase shift mask is high.

From FIG. 20, it can be seen that the overshift angle phase shift mask in which the phase shift amount φ of the transmission control section 36 exceeds 180 degrees has more advantageous fidelity than the existing photomask. Furthermore, it can be seen that particularly good results are obtained when the phase shift amount φ is 300 degrees or more.

Further, as in the first embodiment, by simultaneously considering the range in which the contrast Co is good as shown in FIG. 13, it is possible to select conditions that are more advantageous in terms of fidelity.

As shown in Embodiments 1 and 2 above, with the overshift angle phase shift mask, it is possible to provide a photomask 10 that can perform photolithography with good fidelity using the proximity exposure apparatus 50.

Furthermore, according to the embodiment described above, even if the proximity gap G changes depending on the in-plane position of the photomask 10, it is possible to reduce the change in the shape (including CD) of the transferred image due to the change. A photomask 10 can be provided. In particular, in the large photomask 10 used for flat panel displays, the proximity gap G tends to change due to deflection due to its own weight or due to the holding means of the exposure device, so it is effective to adopt the photomask 10 of this embodiment. be.

Further, according to the embodiment described above, it is possible to provide a photomask 10 that can perform exposure with high fidelity by combining a resist using a negative photosensitive material and a high-pressure mercury lamp.

The transmission control film constituting the transmission control section 36 has its composition and film thickness determined in order to have a predetermined exposure light transmittance and phase shift amount, and the composition changes in the film thickness direction. It may be uniform, or it may be a structure in which films having different compositions or different physical properties are stacked to form one permeation control film.

However, as long as the effects of the present invention are not impaired, a different film (light-shielding film, etching stopper film, etc.) may be additionally provided, and the film pattern formed by the additional film may be different from that of the transmission control film. It may be provided on the upper surface side or the lower surface side.

Further, an additional film pattern (for example, a light-shielding film pattern) may be provided on the outer circumferential side of the transfer pattern 35, and such an additional film pattern may be used during exposure and handling of the photomask 10. A reference mark pattern may also be formed.

Common to the above two embodiments, the photomask 10 of the present invention can be manufactured, for example, by the following manufacturing method.

First, a photomask blank in which a transmission control film is formed on a transparent substrate 21 is prepared. In forming the transmission control film, its material and film thickness are selected so as to satisfy a predetermined transmittance and phase shift amount for exposure light. As a film forming method, a known film forming method such as a sputtering method can be applied.

Next, a resist-attached photomask blank in which a resist film is formed on a transmission control film is prepared. The resist may be of positive type or negative type, but positive type is preferred.

Then, patterning is performed on the photomask blank with resist. Specifically, using a drawing device such as a laser drawing device, drawing is performed based on predetermined pattern data, and development is performed. Furthermore, using the resist pattern formed by development as a mask, dry or wet etching is performed on the transmission control film to form a transfer pattern 35. Then, the resist pattern is peeled off.

According to the above steps, the photomask 10 can be formed by patterning only once (that is, drawing only once). That is, it is preferable that the photomask 10 be formed by patterning only the transmission control film. Additional film formation and patterning may be performed as necessary.

The material of the permeation control film can be, for example, a film containing Si, Cr, Ta, Zr, etc., and an appropriate material can be selected from these compounds.

As the Si-containing film, a Si compound (SiON, etc.), a transition metal silicide (MoSi, TaSi, ZrSi, etc.), or a compound thereof (oxide, nitride, carbide, oxynitride, oxynitride carbide, etc.) is used. be able to.

As the Cr-containing film, a Cr compound (oxide, nitride, carbide, oxynitride, carbonitride, oxynitride carbide) can be used.

The present invention includes a method of manufacturing an electronic device for a flat panel display using a photomask 10.

That is, it includes a step of preparing the above-mentioned overshift angle phase shift mask, and a transfer step of exposing it with the proximity exposure device 50 and transferring the transfer pattern 35 onto the transfer target 51, and the transfer step This is a method for manufacturing an electronic device for a flat panel display, which applies proximity exposure with a proximity gap of 50 to 200 μm.

The photomask 10 can be suitably used for producing a black matrix 52 or a black stripe, but is not limited thereto. However, the photomask of the present invention can be particularly suitably used for the purpose of forming a three-dimensional structure made of a photosensitive material on a transfer target. This is because it is extremely meaningful to be able to obtain excellent fidelity in the shape of the three-dimensional structure formed by the transmission control section surrounded by the closed line and the transparent section surrounding it. be.

Further, the present invention can be suitably applied to a transfer pattern including a so-called dense pattern, such as a line-and-space pattern, in which unit patterns located at distances that optically influence each other are regularly repeated. .

The technical features (constituent features) described in each example can be combined with each other, and new technical features can be formed by combining them.
The embodiments disclosed herein are illustrative in all respects and should not be considered restrictive. The scope of the present invention is indicated by the claims, not the above-mentioned meaning, and is intended to include meanings equivalent to the claims and all changes within the scope.

10 Photomask 21 Transparent substrate 35 Transfer pattern 36 Transmission control section 37 Light transmission section 50 Proximity exposure device 51 Transfer target 52 Black matrix 56 Transfer target (glass substrate)
57 Light source 58 Lighting system

Claims (19)

A photomask for close exposure, comprising a transfer pattern formed by patterning a transmission control film formed on a transparent substrate,
The transfer pattern has a transmission control part in which a transmission control film is formed on the transparent substrate, and a light transmission part through which the transparent substrate is exposed,
A photomask, wherein the transmission control section has a phase shift amount of 255 degrees or more and less than 360 degrees with respect to exposure light that exposes the photomask. The photomask according to claim 1 , wherein the transmission control section has a phase shift amount of 300 degrees or more and less than 360 degrees with respect to the exposure light. When the photosensitive material on the transfer target to which the transfer pattern is transferred is a negative type, the transmission control section corresponds to a region where the photosensitive material is eluted by exposure using the photomask and development. and
When the transmittance of the transmission control section is T, and the threshold of light intensity at which the resist film on the transfer target becomes insoluble by development is Ith, the contrast defined as (Ith-T)/(Ith+T) is: The photomask according to claim 1 or 2 , which has a molecular weight of 0.667 or more. The photomask according to claim 1 or 2 , which is used for exposing a negative photosensitive material. 5. The photomask according to claim 1 , wherein the exposure light includes light having a wavelength of at least one of 313 nm, 334 nm, 365 nm, 405 nm, and 436 nm. 6. The photomask according to claim 1, wherein the transmission control section has a transmittance of 10% or less for exposure light. The photomask according to any one of claims 1 to 5 , wherein the transfer pattern has a line-shaped light-transmitting part with a width of 3 to 10 μm. 6. The photomask according to claim 1, wherein the transfer pattern forms a line-shaped pattern with a width of 10 μm or less on a negative photosensitive material on a transfer target. Any one of claims 1 to 5 , wherein the transfer pattern has a repeating pattern in which the transmission control section and the transparent section are regularly arranged, and the repeating pitch of the repeating pattern is 10 to 35 μm. Photomask described in . 1 . The transfer pattern has a repeating pattern in which the transmission control portion and the transparent portion are regularly arranged, and the transmission control portion has a shape surrounded by a closed line. ~ The photomask described in any one of 5 . 6. The photomask according to claim 1, wherein the transfer pattern has a repeating pattern in which the transmission control portions are regularly arranged, and the transmission control portions are square . 6. The photomask according to claim 1, wherein the transmission control section has a phase shift amount of 330 degrees or less with respect to the exposure light. 6. The photomask according to claim 1 , wherein the transfer pattern is a black matrix or a black stripe forming pattern. 6. The photomask according to claim 1, wherein the transfer pattern is formed by patterning only the transmission control film on the transparent substrate. A step of preparing a photomask according to any one of claims 1 to 5 ,
a transfer step of exposing the photomask using a proximity exposure device and transferring the transfer pattern to a negative photosensitive material film formed on the transfer target;
has
In the transfer step, a method for manufacturing an electronic device for a flat panel display applies proximity exposure with a proximity gap set in a range of 50 to 200 μm. A method for manufacturing a photomask for close exposure, comprising a transfer pattern formed by patterning a transmission control film formed on a transparent substrate, the method comprising:
preparing a photomask blank on which the transmission control film is formed on the transparent substrate;
a patterning step of patterning the transmission control film to form the transfer pattern;
has
The transfer pattern has a transmission control part in which the transmission control film is formed on the transparent substrate, and a light transmission part in which the transparent substrate is exposed,
The transmission control unit has a transmittance of 10% or less and a phase shift amount of 255 degrees or more and less than 360 degrees with respect to the exposure light that exposes the photomask.
Method of manufacturing a photomask. When the photosensitive material on the transfer target to which the transfer pattern is transferred is a negative type, the transmission control section corresponds to a region where the photosensitive material is eluted by exposure using the photomask and development. and
When the transmittance of the transmission control section is T, and the threshold of light intensity at which the resist film on the transfer target becomes insoluble by development is Ith, the contrast defined as (Ith-T)/(Ith+T) is: 17. The method for manufacturing a photomask according to claim 16 , wherein the photomask is 0.667 or more. 18. The photomask manufacturing method according to claim 16 , wherein the exposure light includes light having a wavelength of at least one of 313 nm, 334 nm, 365 nm, 405 nm, and 436 nm. A method of manufacturing an electronic device for a flat panel display, the method comprising:
A step of preparing a photomask by the manufacturing method according to any one of claims 16 to 18 ;
a transfer step of exposing the photomask using a proximity exposure device and transferring the transfer pattern to a negative photosensitive material film formed on the transfer target;
has
In the transfer step, a method for manufacturing an electronic device for a flat panel display applies proximity exposure with a proximity gap set in a range of 50 to 200 μm.

Images