KR102225409B1 - Pattern lithography method, photomask manufacturing method, and display device manufacturing method - Google Patents

Abstract

The present invention provides a method of transferring a pattern having CD accuracy as designed on a transfer object. The present invention is a pattern drawing method for making a photomask provided with a transfer pattern for manufacturing a device for a display device by drawing on a photomask substrate based on predetermined design pattern data. A CD containing the location and error amount of the CD error determined in advance when a CD error for the design value occurs due to the manufacturing process of the display device, using a drawing device that performs drawing with an energy beam on the substrate. A beam intensity correction map forming step of forming a beam intensity correction map for correcting a CD error based on information on the occurrence tendency of errors, and drawing by a drawing device using the beam intensity correction map together with design pattern data A pattern drawing method including a drawing step of performing and a related technique thereof is provided.

Description

A pattern drawing method, a photomask manufacturing method, and a display device manufacturing method TECHNICAL FIELD [PATTERN LITHOGRAPHY METHOD, PHOTOMASK MANUFACTURING METHOD, AND DISPLAY DEVICE MANUFACTURING METHOD]

The present invention relates to a photomask for manufacturing an electronic device, and in particular to a pattern drawing method for obtaining a photomask suitable for manufacturing a device for a display device (FPD).

In Patent Document 1 (hereinafter referred to as Document 1), a method of correcting a photomask for color filters is described. According to this document 1, when a change region map in which the amount of change to the design value due to the process characteristic of the color filter is expressed in line width and coordinates is obtained, and when the change amount is corrected for the initial design value, the change in the single dimension correction region is In the photomask correction method for performing correction from a large area to a small area, in the vicinity of a boundary between a correction target and an adjacent area, correction values are distributed in stages and randomly from the correction area to the adjacent area to be corrected. do.

Japanese Patent No. 5254068

In recent years, in the industry of display devices including liquid crystal displays and organic EL displays, there is a strong demand for miniaturization and high integration of pixels, and displays such as high-speed display and wide viewing angle, while being brighter and more power-saving. Improvement in performance is desired. In response to such high-precision demands, the photomask pattern used when manufacturing a display device (referring to a display device or a device constituting a portion thereof. hereinafter, these are simply referred to as a display device) There is a remarkable trend of miniaturization. For example, in a layer for forming a TFT (thin film transistor) used in a liquid crystal display device or an organic EL display device, or a black matrix (BM) of a color filter, a photo spacer (PS), etc., a fine pattern There is a demand for a method of transferring while securing an accurate CD (Critical Dimension, hereinafter, also used as a meaning of pattern width) as designed.

For example, in the thin film transistor used in the display device, the diameter of the contact hole formed in the interlayer insulating film is 3 μm or less (for example, 1.5 to 3 μm, etc.), or the BM of the color filter is 8 μm or less (for example, For example, a fine pattern such as 3 to 8 μm, etc.) is desired. It is desired that the formation of fine hole patterns, dot patterns, line patterns, and space patterns at this level is performed precisely and precisely.

In addition, in the manufacture of a display device, a photosensitive resin film that becomes a part of the device as a structure is formed on the transfer object (display panel substrate, etc.) to which the transfer pattern of the photomask is transferred, except when a resist film serving as an etching mask is formed. There are also not a few cases where it is formed. In this case, the deviation of the CD from the design value (CD error) not only results in an error in the pattern width, but also causes an error in shape, such as the height of a three-dimensional structure formed by transferring the pattern. , It has the potential to affect performance. In this respect as well, it is important to reduce the deviation from the design value of the CD as much as possible.

By the way, in the field of photomasks for semiconductor device (LSI) manufacturing, in which the degree of integration is higher than that of display devices, and the pattern has been remarkably refined, in order to obtain high resolution, exposure devices have a high numerical aperture (NA) (for example, There is a case in which it is recommended to shorten the wavelength of exposure light by applying an optical system of 0.2 seconds). As a result, in this field, excimer lasers of KrF or ArF (single wavelengths of 248 nm and 193 nm, respectively) have become widely used. An EB (electron beam) drawing apparatus has also been adopted as a drawing apparatus for manufacturing a photomask.

On the other hand, in the field of lithography for manufacturing a display device, it is not common for the above method to be applied in order to improve the resolution. For example, the NA (number of apertures) of the optical system of the exposure apparatus used in this field is about 0.08 to 0.2. In addition, i-line, h-line, or g-line is widely used as an exposure light source, and a broad wavelength light source including these is mainly used to irradiate a large area (for example, a square with one side of the main surface of 300 to 2000 mm). There is a strong tendency to obtain an amount of light and place importance on production efficiency and cost.

Under this situation, nowadays, even in manufacturing of display devices, requests for miniaturization of patterns as described above are increasing. Therefore, in manufacturing display devices, while applying exposure conditions in accordance with the specifications of the exposure apparatus as described above, a large area Even then, a technique for transferring patterns as designed is required.

Document 1 shows that in recent years, high-definition and luminance enhancement of liquid crystal displays, etc., has been desired, and in response to the increase in the number of pixels and the improvement in light transmittance accompanying there, thinning of the black matrix of the color filter has been achieved. I am holding it as a background. Document 1 also raises the problem that, in a lithography process using a photomask, an error may occur in comparison with design data in the pattern after drawing or development due to the inherent characteristics of the pattern drawing device or the etching device. Are doing. In response to this problem, Document 1 proposes a method of improving local dimensional errors in the mask process of a color filter.

However, according to the study of the present inventors, it has been found that the method described in Document 1 is insufficient with respect to correction of the CD error occurring in the manufacturing process of the display device.

Thus, the present inventors have made intensive studies to provide a method of transferring a pattern having CD accuracy as designed on an object to be transferred, while avoiding the above problem, and have come to complete the present invention.

(First aspect)

In a pattern drawing method for making a photomask provided with a transfer pattern for manufacturing a device for a display device by drawing on a photomask substrate using a drawing device based on predetermined design pattern data,

When a CD error for the design value occurs due to the manufacturing process of the display device device,

A beam intensity correction map forming step of forming a beam intensity correction map for correcting the CD error, based on information on the occurrence tendency of the CD error, including the location and error amount of the CD error, as determined in advance; and ,

A drawing step of performing drawing by the drawing device using the beam intensity correction map together with the design pattern data,

It is a pattern drawing method characterized by including a.

(Second aspect)

The second aspect of the present invention,

The manufacturing process of the device for a display device includes an exposure process of exposing the photomask with an exposure apparatus,

The CD error is an error caused by exposure conditions by the exposure apparatus, and is the pattern drawing method according to the first aspect.

(3rd aspect)

The third aspect of the present invention,

The exposure apparatus is a pattern drawing method according to the second aspect, characterized in that a projection exposure method is applied in which a transfer pattern of a photomask is transferred onto an object to be transferred by scanning a plurality of lenses.

(4th aspect)

The fourth aspect of the present invention,

The exposure apparatus is a pattern drawing method according to the second aspect, characterized in that a proximity exposure method is applied.

(Fifth aspect)

The fifth aspect of the present invention,

The transfer pattern is a pattern drawing method according to any one of the first to fourth aspects, characterized in that it includes a repeating pattern in which a plurality of unit patterns are regularly arranged.

(6th aspect)

The sixth aspect of the present invention,

In the drawing step, it is a pattern drawing method according to any one of the first to fifth aspects, characterized in that multiple drawing is performed.

(7th aspect)

A seventh aspect of the present invention is a method for manufacturing a photomask including the drawing process described in any one of the first to sixth aspects.

(8th aspect)

The eighth aspect of the present invention,

A step of preparing a photomask by the manufacturing method according to the seventh aspect, and

A device for a display device comprising transferring the transfer pattern onto a transfer object by an exposure apparatus applying a projection exposure method in which a transfer pattern of a photomask is transferred onto a transfer object by scanning a plurality of lenses It is a manufacturing method of.

(9th aspect)

The ninth aspect of the present invention,

A step of preparing a photomask by the manufacturing method according to the seventh aspect, and

It is a manufacturing method of a device for a display device comprising transferring the transfer pattern onto an object to be transferred by an exposure apparatus to which a proximity exposure method is applied.

According to the present invention, it becomes possible to reliably and efficiently correct a CD error of a pattern that occurs in the manufacturing process of a display device.

1A is a schematic diagram showing the configuration of a lens in a projection exposure apparatus for manufacturing a display device of a lens scan method, and (b) is a structure of a lens formed at a connection portion between the lenses, and the object to be transferred is It is a schematic diagram showing the light intensity distribution when the intensity of the received irradiation light is larger (upper side) and smaller (lower side) than other portions.
Fig. 2(a) is a schematic diagram showing the location of a CD error occurring on the subject by the exposure apparatus (the upper view shows the fluctuation of the light intensity by the exposure apparatus, and the lower diagram is the CD error on the subject caused by it) (B) is a schematic diagram of a beam intensity correction map for reducing the occurrence of the CD error (top is a schematic diagram showing the amount of correction of the beam intensity as a CD change amount, and the bottom is a beam intensity) It is a plan schematic diagram of CD change by the correction map), and (c) is a plan schematic diagram showing a state in which linear irregularities due to a CD error disappear when exposed using a corrected photomask.
Fig. 3(a) is a conceptual diagram of the correction step of the CD, which occurs when CD correction is performed by adjusting the design pattern data, and (b) is a nearly continuous, obtained when the beam intensity correction according to the present invention is performed. It is a conceptual diagram showing the correct CD correction.
Fig. 4(a) shows a CD distribution map formed on the object to be transferred due to fluctuations in irradiation intensity generated at the lens connection portion of the exposure apparatus, and (b) is the CD of the photomask formed by the drawing method of the present invention. The distribution map is shown, and (c) shows the CD distribution map of the transferred image obtained on the object to be transferred by exposing the photomask having the CD distribution of (b).

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

In manufacturing a display device, a high-precision photomask manufacturing technique is required in which even a transfer pattern with a high degree of difficulty including a small CD pattern is stably formed according to a design value. On the other hand, with such a photomask manufacturing technology, even if a CD accuracy meets specifications and a photomask with no problems is used, the dimensions of the transferred image formed on the object to be transferred (display panel substrate, etc.) There are several factors that cause a CD error because it fluctuates without being changed.

For example, when in-plane distribution (non-uniformity) occurs in the film thickness of the resist film formed on the transfer object before exposure, or when in-plane non-uniformity occurs in the supply of the developer during development, etc. In-plane, there are cases where non-uniformity occurs in the CD, which should be uniform. Particularly, the transfer object for a display device is large in size (about 1000 mm to 3400 mm per side, etc.), and depending on the structure of the resist coating device, the developing/etching device, the liquid flow of the wet treatment, etc., the in-plane processing conditions are completely uneven. It cannot be avoided.

In addition, even in the exposure apparatus used when exposing the photomask, the distribution of the amount of light in the plane may occur due to the cause of the device configuration.

As long as the same device is used, the in-plane non-uniformity of the processing conditions and exposure conditions as described above often appears with reproducibility, and it is possible to reduce the influence by grasping this tendency and taking measures to reduce it. I think. Specifically, CD non-uniformity on the transfer, which is caused by the in-plane non-uniformity factor of the processing conditions and exposure conditions as described above, is reflected in the design pattern data of the photomask in advance, and from the CD target value caused by such non-uniformity. It can be assumed that it is effective to perform correction to cancel the tendency of increase or decrease of.

By the way, in manufacturing a photomask, first, pattern data is created based on the design of a device (display device, etc.) to be obtained (design pattern data). Then, using this pattern data, drawing is performed on a photomask substrate by a drawing apparatus. A drawing apparatus draws by irradiation of an energy beam, and in particular, a laser drawing apparatus using a laser beam is widely used.

Examples of the photomask substrate include a photomask blank in which an optical film (such as a light shielding film) and a resist film for forming a photomask pattern and a resist film are formed on a transparent substrate. After drawing is performed on the resist film of the photomask substrate, a photomask with a transfer pattern is obtained by performing patterning of the optical film using the resist pattern formed by development as an etching mask.

By the way, when the photomask fabricated in this way is exposed by an exposure apparatus and the CD of the pattern formed on the object to be transferred is measured, the CD may fluctuate depending on the in-plane position on the object to be transferred. That is, a difference (CD error) occurs between the CD of the pattern formed on the object to be transferred and the target CD according to the design value, and the amount of this CD error may differ depending on the position in the plane on the object to be transferred. This main cause is as described above.

Regarding such in-plane variation of CD error, it is considered to reduce the CD error by grasping the error occurrence tendency, including the location and amount of error, in advance, and correcting the data by reflecting the identified trend in the design pattern data of the photomask. I can. If appropriately corrected correction pattern data is used, it is considered that the CD error amount can be suppressed to be less than the allowable range over the entire surface.

By the way, in Document 1, it describes as follows. That is, a pattern is transferred onto a glass substrate coated with a photosensitive resin using a photomask manufactured with initial design values, and a single-dimensional correction region of a color filter pattern obtained through each process of etching is currently mapped. As a result, a wide tendency of the single dimension correction area such as "the pattern dimension on the lower end side of the mask is formed to be smaller than the design value as a whole" has been observed. This is thought to have occurred depending on processes such as etching. So, based on each of the mapped divisions, the design values of the photomasks corresponding thereto are adjusted. The design value of the photomask corresponding to the region to be corrected is adjusted to be larger than the initial setting value, and the dimension after the process is set to be within an appropriate range.

In addition, Document 1 has a problem in that, when uniformly corrected according to the above-described mapping, a large dimensional change "step difference" appears at the boundary between the correction region and the adjacent region. Since the dimensional change in the vicinity of the boundary is desired to be as gentle as possible, in the method of Document 1, the correction amount at the boundary is randomly distributed rather than continuously arranged one of the correction values of the adjacent regions. In this way, it is said that the size of the color filter does not change abruptly across a certain area and becomes an average single-dimensional correction area.

By the way, according to the examination of the present inventor, the said method also has a problem. That is, in the case of adjusting the design value for the mapped division, the pattern data of the photomask, the design pattern of the photomask is different for each product to be obtained. Even if there is, it is necessary to adjust the design value for each design pattern. Specifically, in the case of a CD error caused by the exposure mechanism of the exposure apparatus, it is beneficial to perform the same correction as long as the exposure apparatus is used, but design each time when manufacturing a new photomask with a different design pattern. It is inefficient because it is necessary to adjust the value.

For example, many of the transfer patterns for display device manufacturing include a repeating pattern in which unit patterns are regularly arranged. The design pattern data in this case holds only the smallest unit of repetition (e.g., 1 pixel) as a pattern, and gives the number of rows and columns in each of the X and Y directions, and an array of pixels such as several million and tens of millions of pixels is obtained. It can be expressed (hereinafter, also referred to as array arrangement). This is advantageous in that the data capacity can be suppressed, and the number of steps required for design is also drastically reduced.

By the way, when this array arrangement is applied, it becomes remarkably difficult to adjust the design value of a photomask only for a predetermined division among design pattern data.

In addition, in Document 1, as described above, in order to make the dimensional change as smooth as possible in the vicinity of the boundary portion of the region to be corrected, the correction amount at the boundary portion employs a method of randomly distributing and distributing correction values of adjacent regions. have. In this case, there is a problem that the application of the array arrangement becomes more difficult.

So, the drawing method of the present invention,

In a pattern drawing method for making a photomask provided with a transfer pattern for manufacturing a device for a display device by drawing on a photomask substrate based on predetermined design pattern data,

On the photomask substrate, a drawing device for drawing with an energy beam is used,

When a CD error for the design value occurs due to the manufacturing process of the display device device,

A beam intensity correction map forming step of forming a beam intensity correction map for correcting the CD error, based on information on the occurrence tendency of the CD error, including the location and error amount of the CD error, as determined in advance; and ,

And a drawing step of performing drawing by the drawing apparatus using the beam intensity correction map together with the design pattern data.

Here, the design pattern data is pattern data designed for a specific layer based on the design of a device to be obtained (here, a device for a display device). Consider a case where this design pattern data is drawn on a photomask substrate by a drawing device (here, referred to as a laser drawing device) that scans an energy beam. In addition, as a laser drawing apparatus, a method of scanning a laser beam on a photomask substrate, a method of projecting a laser beam by a mirror or the like is not particularly limited.

A photomask substrate refers to a photomask blank in which an optical film for forming a photomask pattern is formed on a transparent substrate, and a resist film is formed, or a predetermined optical film formed on a transparent substrate, after patterning is performed. It may be a photomask intermediate in which a resist film is formed on the substrate to perform patterning of another optical film. The resist film may be of a positive type or a negative type, but a positive type is generally used for a photomask in this field.

As the optical film, in addition to the light-shielding film, a semi-transmissive film having a predetermined light transmittance is exemplified. As the semi-transmissive film, it may be a phase shift film that shifts light of a representative wavelength (for example, any wavelength in the range of i-line to g-line) by approximately 180 degrees among wavelengths included in exposure light, or phase shifting A film having an amount of 90 degrees or less (preferably 60 degrees or less) can also be used. About 180 degrees means 180±30 degrees. The light transmittance of the semitransmissive film can be, for example, about 5 to 60% with respect to the representative wavelength.

Hereinafter, an embodiment of the present invention will be described by taking as an example the case where the deterioration of the CD accuracy of the pattern obtained on the object to be transferred occurs by the exposure apparatus used for exposure of the photomask. As a specific example, due to the structure of the exposure apparatus, the irradiation amount of exposure light received by the photomask is non-uniform in the plane, whereby the CD at a specific position on the transfer image formed on the object to be transferred is at the target value by design. If it deviates, etc. are mentioned.

As a projection exposure apparatus for manufacturing a display device, there is one employing a lens scanning method as described above. This transfers the transfer pattern onto the object to be transferred by simultaneously moving a plurality of parallel projection lenses and scanning the entire transfer pattern included in the photomask. In order not to generate a gap between the plurality of lenses, a slight overlap of irradiation is given to the connecting portion of the adjacent lenses, and the intensity of irradiation is adjusted so that the intensity of the irradiation becomes the same as that of other areas in the overlapping portion ( Fig. 1(a)).

However, in spite of the precise and precise adjustment of the irradiation intensity of the connection portion, a phenomenon in which the CD becomes slightly larger or smaller than the other portions is observed on the object to be transferred at the position corresponding to the connection portion. This CD fluctuation is slight, but when the display device is used, since the CD of the trajectory of the connection portion is different from that of other areas, it may be recognized as a straight spot by human vision. As a cause of this, there may be a slight increase or decrease in the light intensity at the connection portion, and there may be a case where a difference in conditions with other regions may occur due to overlapping exposure. In Fig. 1(b), the case where the light intensity of the connecting portion is larger than that of the other portions (upper side) and the light intensity distribution when it is smaller (lower side) is illustrated.

For example, in the case where a negative resist (photosensitive resin) film is formed on the transfer object, and the light intensity is greater than that of other parts, in the resist pattern after development, the CD becomes greater than the target value in the region, and the light intensity If is smaller than the other part, the CD becomes smaller than the target value. Therefore, when development is performed after exposure and the thin film to be processed is etched using the formed resist pattern, linear irregularities are visually recognized due to the non-uniformity in the light intensity. Fig. 2(a) shows this state.

Therefore, in order to reduce such CD fluctuations, it is conceivable to adjust the CD of the corresponding portion in the photomask transfer pattern in advance, as in the method of Document 1. That is, since the CD fluctuation caused by the exposure apparatus has reproducibility, it is considered useful to form the design pattern data of the photomask so as to offset the CD fluctuation if the tendency is quantitatively grasped. However, this method has a problem as described above.

On the other hand, in the present invention, the correction for reducing the CD error is not performed by adjustment of the design pattern data, but information on the occurrence tendency of the CD error, including the location and the amount of the CD error, as determined in advance. On the basis of, a beam intensity correction map for correcting the CD error is formed. And in the drawing process of a photomask, this beam intensity correction map is used together with design pattern data.

In this embodiment, a laser drawing device is used as the drawing device. The laser drawing apparatus draws by setting the irradiation intensity (power) of a laser beam emitted by a laser light source to a numerical value determined by a user. However, the irradiation intensity of this laser beam is set to be higher or lower than other portions (a portion as designed) in a specific portion in the drawing area, and this is stored in the storage device as a beam intensity correction map. That is, in advance, in order to grasp the tendency of the CD error generated by the exposure apparatus with respect to its position and error amount, and to cancel the CD error by reflecting the information of this CD error tendency, the beam intensity of the drawing apparatus It is enough to acquire a beam intensity correction map for which is set.

At this time, the beam intensity correction map is independent from the design pattern data of a specific photomask. Therefore, in the case where a display device is to be manufactured using the same exposure device, it is a map that can be used repeatedly in common even when the design of the transfer pattern included in the photomask to be used is individually different.

Since it is unnecessary to give changes to the design pattern data, there is no influence on the formation of the design pattern data by array arrangement.

As shown in Fig. 2(b), when a beam intensity correction map in which the beam intensity is corrected to cancel the CD error is prepared at the location of the CD error generated by the exposure apparatus (Fig. 2(a)) do.

Fig. 2A is a schematic diagram showing a location where a CD error occurs on an object to be transferred by the exposure apparatus. The upper side of Fig. 2A is a plane showing the distribution of light intensity generated during exposure (horizontal axis: position, vertical axis: light intensity), and the lower side is a plane showing the appearance of linear irregularities observed by this CD error. It is a schematic diagram. In correspondence with the connecting portions of the plurality of lenses of the exposure apparatus, unevenness has occurred.

Fig. 2B is a schematic diagram of a photomask pattern by drawing using a beam intensity correction map in which the beam intensity is corrected to cancel the CD error at the location of the CD error generated by the exposure apparatus. 2(b) is a schematic diagram (horizontal axis: position, vertical axis: CD (unit: nm)) showing the correction amount of the beam intensity as a CD change amount, and the lower side is a beam intensity correction map as CD It is a schematic plan view shown as a change.

Fig. 2(c) shows a transfer object obtained by performing pattern transfer by an exposure apparatus using the photomask shown in Fig. 2(b). The straight spot due to the CD error disappears. In Fig. 2(c), portions corresponding to the disappeared linear irregularities are indicated by broken lines for ease of understanding.

A further advantage of correcting the CD error by beam intensity correction is that the correction of the beam intensity can be performed substantially steplessly (continuously), unlike CD correction by adjusting the design pattern data. . That is, the adjustment of the correction amount of the beam intensity can be set very finely according to the CD error. For this reason, at the boundary between the region with correction and the region without correction, or between regions with different correction amounts, the difference in light intensity does not become present, so that the boundary can be smoothly corrected so that the boundary cannot be recognized. This state is schematically shown in FIG. 3. In Fig. 3, the horizontal axis represents the position, and the vertical axis represents the correction amount.

As shown in Fig. 3A, when CD correction is performed by adjusting the design pattern data, a correction step of the CD occurs. On the other hand, as shown in Fig. 3B, when the beam intensity correction according to the present invention is performed, almost continuous CD correction can be realized.

4 shows an example of CD correction according to the present invention.

Fig. 4A shows a CD distribution map (bubble chart) of a pattern (transfer image) formed on a transfer object when a transfer pattern of a photomask is exposed using an exposure apparatus. A CD error occurs in a specific region (on a straight line in the vertical direction) due to fluctuations in the irradiation intensity generated at the lens connection portion of the exposure apparatus. Here, the CD of the pattern formed on the object to be transferred is shown in a large-small relationship based on the target CD based on the design value. Dark gray ● indicates that the CD is larger than the target CD, and white ○ indicates that the CD is smaller than the target CD. The size of the bubble represents the difference from the target CD.

In FIG. 4A, a CD error occurred in a straight line at regular intervals was seen at a position corresponding to the position of the lens connection portion of the exposure apparatus of the lens scanning method. According to FIG. 4A, it can be seen that the CD was larger than the target CD at a position corresponding to the lens connection part. Information on the tendency regarding the location and size of such a CD error can be obtained by exposure using a test mask or the like in which a predetermined transfer pattern is formed in advance.

Next, a beam intensity correction map is formed based on the information on the occurrence tendency of the CD error obtained above (beam intensity correction map forming step). The beam intensity correction map is a two-dimensional map formed to correct the irradiation intensity of the drawing laser at each position on the coordinates greater than or less than a reference value so as to cancel the occurrence of the CD error. That is, it can be said that the laser power distribution in the plane to be drawn is mapped based on the coordinates.

FIG. 4B shows a beam intensity correction map applied at the time of drawing a photomask in order to cancel the CD error based on the tendency of the location of the CD error and the amount of error determined by FIG. 4A. Is a CD distribution map of the photomask according to the present invention obtained by using this. That is, FIG. 4B shows that by using design pattern data based on a desired design together with the beam intensity correction map, drawing reflecting the correction of the laser beam intensity (drawing step), and the resulting photomask Shows the CD distribution map.

FIG. 4C is a CD distribution map of a pattern (transfer image) obtained on an object to be transferred when exposure is performed using the photomask of FIG. 4B and the same exposure apparatus (exposure process). The CD error of the lens connection portion is almost eliminated, and the CD fluctuation in the plane is reduced.

In the present embodiment, the beam intensity correction map is independent from the design pattern data of a specific photomask, and is a map of the beam intensity in which intensity correction is performed to cancel the CD error by reflecting the tendency of the CD error occurring on the object to be transferred. to be. In addition to the case where the exposure apparatus is the same magnification exposure, when there is a magnification, it can be formed in consideration of the magnification similarly to the formation of the transfer pattern of the photomask.

With the pattern drawing method of the present invention, for example, it is possible to easily realize correction of about ±0.20 µm for a CD on a photomask. When this correction range is insufficient with respect to the amount of CD error generated, it can be adjusted by changing the characteristics of the resist applied on the photomask substrate or by changing the reference amount of laser irradiation at the time of drawing.

Further, in order to expand the correction range, multiple drawing can be suitably used. For example, if the overlapping drawing is performed twice, it is useful because the range in which the beam intensity can be corrected can be expanded. By suitably using multiple drawing, for example, it becomes possible to perform correction on the order of ±0.70 to ±1.5 µm.

In the above embodiment, in the case of using the exposure apparatus of the projection exposure method to which the lens scan is applied, the CD error to be corrected has been described as an example that occurs due to the lens connection portion of the exposure apparatus. It is not limited to this CD error. In addition, the present invention can be applied to the case of using a projection exposure apparatus of another method.

As the projection exposure apparatus, those having an optical system NA (number of apertures) of 0.08 to 0.2 and a coherence factor (σ) of about 0.4 to 0.9 can be preferably applied. Further, as the exposure light, a light source including a wavelength range of about 300 to 800 nm, specifically, any one of i-line, h-line, and g-line is useful. A lamp including all of the i-line, h-line, and g-line may be used.

In addition, the present invention can also be applied to a case where a problem that the CD becomes uneven in the plane occurs in the case of using the exposure apparatus of the proximity exposure method. In the proximity exposure, a photomask is supported through a slight gap on a horizontally stacked transfer object, and the transfer pattern possessed by the photomask is transferred. However, since the photomask is bent by its own weight and receives a predetermined force from the support member of the photomask, the size of the gap becomes non-uniform in the plane, and accordingly, the CD on the transferred image is also non-uniform. The present invention can also be suitably applied to the CD error occurring in such an exposure method.

That is, it is sufficient to grasp the tendency of occurrence of errors, including the location of the CD error and the amount of error, in advance, to form a beam intensity correction map based on this, and to draw a photomask using this.

Also in proximity exposure, the wavelength range of exposure light to be applied is the same as described above.

Of course, it is needless to say that the present invention can be applied even in cases other than the above, when a CD error with reproducibility occurs in the manufacturing process of the display device.

There are no particular restrictions on the design or use of the transfer pattern of the photomask to which the present invention is applied.

For example, it may be assumed that a unit pattern corresponding to a pixel includes a repeating pattern in which a plurality of unit patterns are regularly repeatedly arranged. In this case, when a CD error occurs, it is likely to be visually recognized by the human eye in the final display device even if the error amount is small due to reasons such as being arranged in a straight line or concentrated in a specific portion. However, the correction of the CD error according to the present invention is advantageous because it is possible to perform precise and precise correction so that the boundary between the corrected portion and its adjacent portion cannot be recognized.

The resist (photosensitive resin) on the transfer object may be of a positive type or a negative type.

According to the present invention, it is possible to cope with the trend of miniaturization of patterns. That is, with the miniaturization of the pattern CD, the range of allowable CD fluctuations is also very narrow, but the application of the present invention can be advantageously used for this.

Claims (11)

In a pattern drawing method for making a photomask provided with a transfer pattern for manufacturing a device for a display device by drawing on a photomask substrate based on predetermined design pattern data,
On the photomask substrate, a drawing device for drawing with an energy beam is used,
Due to the manufacturing process of the display device, when a CD error, which is a difference between the CD of the pattern on the object to be transferred formed by exposing the photomask using the exposure apparatus, and the target CD according to the design value occurs,
A beam intensity correction map forming step of forming a beam intensity correction map for correcting the CD error on the basis of information on the occurrence tendency of the CD error including the location of the CD error and the amount of the error determined in advance;
A drawing step of performing drawing by the drawing device using the beam intensity correction map together with the design pattern data,
It characterized in that it comprises a, pattern drawing method. The method of claim 1,
The manufacturing process of the device for a display device includes an exposure process of exposing the photomask with an exposure apparatus,
The CD error is an error caused by an exposure condition by the exposure apparatus. The method of claim 2,
The exposure apparatus employs a projection exposure method in which a transfer pattern of a photomask is transferred onto an object to be transferred by scanning a plurality of lenses. The method of claim 2,
The exposure apparatus is a method of drawing a pattern, characterized in that a proximity exposure method is applied. The method according to any one of claims 1 to 4,
The transfer pattern comprises a repeating pattern in which a plurality of unit patterns are regularly arranged. The method according to any one of claims 1 to 4,
In the drawing process, a pattern drawing method characterized in that multiple drawing is performed. The method according to any one of claims 1 to 4,
The pattern drawing method, wherein the NA of the optical system of the exposure apparatus is 0.08 to 0.2. The method according to any one of claims 1 to 4,
The light source of the exposure apparatus includes any of i-line, h-line, and g-line. It is a manufacturing method of a photomask, and the manufacturing method of a photomask including the drawing process in any one of Claims 1-4. It is a manufacturing method of a device for a display device,
A step of preparing a photomask by the manufacturing method according to claim 9, and
A device for a display device comprising transferring the transfer pattern onto the transfer object by means of an exposure apparatus applying a projection exposure method in which a transfer pattern of a photomask is transferred onto a transfer object by scanning a plurality of lenses Manufacturing method. It is a manufacturing method of a device for a display device,
A step of preparing a photomask by the manufacturing method according to claim 9, and
A method of manufacturing a device for a display device comprising transferring the transfer pattern onto an object to be transferred by an exposure apparatus to which a proximity exposure method is applied.

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