JP6681945B2 - Photomask manufacturing method for display device manufacturing, drawing apparatus, photomask inspection method, and photomask inspection apparatus - Google Patents

Description

  The present invention relates to a photomask that is advantageously used for manufacturing a semiconductor device and a display device (LCD, organic EL, etc.), and relates to a manufacturing method and device, an inspection method and device thereof.

  It is desired to increase the accuracy of the transfer pattern formed on the photomask and further increase the inspection accuracy of the formed transfer pattern.

  Japanese Patent Application Laid-Open No. 2010-134433 discloses a drawing method and a drawing apparatus capable of increasing the coordinate accuracy of a photomask pattern when it is transferred onto a transfer target. In particular, in the photomask manufacturing process, the problem that the pattern as designed is not formed on the transfer target is solved because the shape of the film surface (pattern formation surface) when drawing the transfer pattern is different from that at the time of exposure. Therefore, a method for obtaining the corrected drawing data is described.

JP, 2010-134433, A

  In manufacturing a display device, a photomask having a transfer pattern based on the design of a device to be obtained is often used. As devices, liquid crystal display devices and organic EL display devices represented by smartphones and tablet terminals are required to have bright, power-saving, fast operation speed, and beautiful images with high resolution. Therefore, a new technical problem has been revealed by the inventors with respect to the photomask used for the above-mentioned applications.

  In order to clearly express a fine image, it is necessary to increase the pixel density, and at present, a device with a pixel density exceeding 400 ppi (pixel per inch) is about to be realized. Therefore, the design of the transfer pattern of the photomask is in the direction of miniaturization and high density. By the way, many electronic devices including display devices are three-dimensionally formed by stacking a plurality of layers in which fine patterns are formed. Therefore, it is important to improve the coordinate accuracy in these multiple layers and to coordinate the coordinates with each other. That is, if the pattern coordinate accuracy of each layer does not satisfy the predetermined level, the completed device does not operate properly. Therefore, the allowable range of coordinate shift required for each layer tends to become smaller and smaller.

  By the way, according to Patent Document 1, the shape change amount between the shape of the film surface in the drawing step of the photomask blank and the shape of the film surface at the time of exposure is calculated, and drawing is performed based on the calculated shape change amount. It is described that the design drawing data used is corrected. In this document, at the stage of drawing the transfer pattern, the film surface of the substrate (the surface on the side where the film is formed in the transparent substrate, the surface on which the film is formed in the photomask blank, and the pattern in the photomask) Among the factors of deformation from the ideal plane in the formed surface.), There is described a method of obtaining corrected drawing data by distinguishing between the amount that remains during exposure and the amount that disappears during exposure.

When a pattern is drawn on a photomask blank with photoresist by a drawing device, the photomask blank is placed on the stage of the drawing device with its film surface facing upward. At that time, the deformation factor of the surface shape of the film surface of the photomask blank from the ideal plane is
(1) Insufficient flatness of the stage,
(2) Deflection of the substrate due to the inclusion of foreign matter on the stage,
(3) Asperity on the film surface of the photomask blank,
(4) Deformation of the film surface due to irregularities on the back surface of the photomask blank (that is, (3) and deformation of the film surface due to variations in substrate thickness),
It is thought that there is. Therefore, the surface shape of the photomask blank in this state is formed by accumulating the above four factors. Then, drawing is performed on the photomask blank in this state.

  On the other hand, when the photomask is mounted on the exposure apparatus, it is fixed by making the film surface downward and supporting only the outer edge of the photomask. Place the transferred object with the resist film formed (also called the processed object because it is processed by etching after the pattern is transferred) under the photomask and from the top of the photomask (from the back side) Irradiate exposure light. In this state, among the above four deformation factors, (1) insufficient flatness of the stage and (2) deflection of the substrate due to the inclusion of foreign matter on the stage disappear. Further, (4) the unevenness on the back surface of the substrate remains in this state, but the surface shape of the back surface on which no pattern is formed does not affect the transfer of the front surface (pattern forming surface). On the other hand, the deformation factor that remains when the photomask is used in the exposure apparatus is (3) above.

  That is, the deformation factors due to (1), (2), and (4) exist at the time of drawing and disappear at the time of exposure. Due to this change, a coordinate shift occurs between drawing and exposure. Therefore, the design drawing data is corrected to be drawing data for the change amount of the surface shape from the ideal plane, which is caused by (1), (2), and (4), while (3) is a factor. If the change in the surface shape is not reflected in the above correction, a more accurate photomask having the transfer performance of the coordinate design data can be obtained.

  Therefore, according to the method of Patent Document 1, the coordinate accuracy of the pattern formed on the transfer target can be improved.

  On the other hand, the photomask in the exposure apparatus is held and supported substantially horizontally by the holding member of the exposure apparatus in the holding area near the outer edge of the substrate. At this time, the substrate is deformed by being forcibly restrained by the holding member. Further, in the case of a photomask for manufacturing a display device, since a large-area substrate is supported only near the outer edge of the substrate, it may be bent due to its own weight. In this case, the deformation of the film surface may affect the area where the pattern of the photomask is formed, and the coordinate accuracy of the area may be deteriorated. The present inventor has found that considering the miniaturization and high integration of patterns in currently developed high-performance display devices and the like, it is significant to consider such fine influences.

  For example, a device such as a display device is formed by laminating patterned thin films, and each laminated layer is formed by a transfer pattern of a different photomask. It goes without saying that the individual photomasks used are manufactured under strict quality control. However, since the individual photomasks are different, it is difficult to make all the flatness of the surface to be a perfect ideal plane, and it is also possible to make the film surface shapes to be the same in a plurality of photomasks. Have difficulty.

  Therefore, there is an individual difference in the film surface shape of each photomask, and if the drawing data is corrected in consideration of the film surface shape shown when these photomasks are held in the exposure apparatus. Therefore, it is possible to form a transfer pattern with higher coordinate accuracy.

That is, in comparison with the method of Patent Document 1, in preventing deterioration of coordinate accuracy due to a difference in film surface orientation between drawing and exposure, the accuracy is further improved and the yield of a device having a plurality of layers is increased. In consideration of the individual difference in the film surface shape of the photomask substrate used for each layer and the influence of the force exerted on them in the exposure apparatus, there is a method of substantially eliminating the deterioration of transferability due to this influence. It has been found by the present inventor to be beneficial.
By the way, the above-mentioned Document 1 describes a step of placing a photomask blank on the stage of a drawing apparatus with the film surface facing upward, and measuring the height distribution of the upper surface of the photomask blank in this state. ing. This step is useful in that it makes it possible to quantify the consequences of the above four factors. However, this step has a demerit that the occupation time of the drawing device of the photomask blank is increased. The present inventor has also noticed that there is a potential technical problem to improve the photomask production efficiency and the cost of the drawing device occupancy time, because the effect is large.

  Therefore, the present invention solves the above-mentioned problems and is capable of improving the coordinate accuracy of a pattern formed on a transferred body, a photomask manufacturing method, a drawing apparatus, a photomask inspection method, a photomask inspection apparatus, Another object of the present invention is to provide a method for manufacturing a display device.

In order to solve the aforementioned problems, the present invention has the following configurations.
(Structure 1)
A photomask blank in which a thin film and a photoresist film are formed on the main surface of the substrate is prepared, and a drawing device is used to draw a predetermined transfer pattern.
A step of preparing pattern design data A based on the design of the predetermined transfer pattern,
A step of preparing thickness distribution data T showing the thickness distribution of the substrate,
The step of preparing transfer surface shape data C, which shows the shape of the main surface when the photomask is held in an exposure device,
A step of obtaining drawing difference data F using the thickness distribution data T and the transfer surface shape data C;
A step of calculating the coordinate deviation amount at a plurality of points on the main surface corresponding to the drawing difference data F, and obtaining the drawing coordinate deviation amount data G;
A method of manufacturing a photomask, comprising: a drawing step of drawing on the photomask blank using the drawing coordinate deviation amount data G and the pattern design data A.

(Configuration 2)
A photomask blank in which a thin film and a photoresist film are formed on the main surface of the substrate is prepared, and a drawing device is used to draw a predetermined transfer pattern.
A step of preparing pattern design data A based on the design of the predetermined transfer pattern,
Thickness distribution data T indicating the thickness distribution of the substrate, and a step of preparing substrate surface shape data B indicating the surface shape of the main surface,
When the photomask is held in the exposure apparatus, the displacement caused in the surface shape is reflected on the substrate surface shape data B, showing the shape of the main surface when held in the exposure apparatus, A step of obtaining the transfer surface shape data C,
A step of obtaining drawing difference data F using the thickness distribution data T and the transfer surface shape data C;
A step of calculating the coordinate deviation amount at a plurality of points on the main surface corresponding to the drawing difference data F, and obtaining the drawing coordinate deviation amount data G;
A method of manufacturing a photomask, comprising: a drawing step of drawing on the photomask blank using the drawing coordinate deviation amount data G and the pattern design data A.

(Structure 3)
When the substrate is held in the exposure apparatus, of the deformation of the main surface, the self-weight deformation amount data R indicating the deformation amount of the main surface due to the self-weight deflection of the substrate is obtained,
In the step of obtaining the drawing difference data F, the self-weight deformation data R is used together with the thickness distribution data T and the transfer surface shape data C to manufacture the photomask according to configuration 1 or 2. Method.

(Structure 4)
The substrate surface shape data B is a plurality of measurements on the main surface of the photomask blank, or a substrate for forming the photomask blank, with the main surface being held substantially vertically. 3. The method for manufacturing a photomask according to configuration 2, which is obtained by measuring a position of a point.

(Structure 5)
The thickness distribution data T is a plurality of measurement points on the main surface with the photomask blank, or a substrate for the photomask blank being held so that the main surface is substantially vertical. 5. The method for manufacturing a photomask according to any one of configurations 1 to 4, which is obtained by measuring the position of.

(Structure 6)
Regarding the coordinate deviation component peculiar to the drawing device, the coordinate deviation peculiar data Q is obtained in advance,
In the drawing step, drawing is performed on the photomask blank by using the coordinate deviation peculiar data Q together with the drawing coordinate deviation amount data G and the pattern design data A. Configuration 1 5. The method for manufacturing a photomask according to any one of 5 to 5.

(Structure 7)
7. The method of manufacturing a photomask according to any one of configurations 1 to 6, wherein a finite element method is used in the step of obtaining the transfer surface shape data C.

(Structure 8)
In the drawing step, drawing is performed by using the corrected pattern data H obtained by correcting the pattern design data A based on the drawing coordinate deviation amount data G. 7. The method for manufacturing a photomask according to any one of 6 to 6.

(Configuration 9)
In the drawing step, the coordinate system of the drawing apparatus is corrected based on the drawing coordinate deviation amount data G, and drawing is performed using the obtained corrected coordinate system and the pattern design data A. 7. The method for manufacturing a photomask according to any one of configurations 1 to 6.

(Configuration 10)
10. The photomask according to any one of Configurations 1 to 9, wherein a plurality of holding points held by a holding member are arranged on a plane when the photomask is held in an exposure apparatus. Production method.

(Configuration 11)
A drawing device used for drawing a transfer pattern on a photomask blank in which a thin film and a photoresist film are formed on a main surface of a substrate,
Pattern design data A of the transfer pattern,
Thickness distribution data T indicating the thickness distribution of the substrate, and transfer surface shape data C indicating the main surface shape of the substrate in a state where the substrate is held by an exposure device.
Input means for inputting,
Using the thickness distribution data T and the transfer surface shape data C, calculation means for calculating the drawing coordinate deviation amount data G at a plurality of points on the main surface,
A drawing apparatus comprising: a drawing unit that draws on the photomask blank using the drawing coordinate shift amount data G and the pattern design data A.

(Configuration 12)
A drawing device used for drawing a transfer pattern on a photomask blank in which a thin film and a photoresist film are formed on a main surface of a substrate,
Pattern design data A of the transfer pattern,
Thickness distribution data T showing the thickness distribution of the substrate,
Showing the shape of the main surface of the substrate, substrate surface shape data B,
Input means for inputting information about a holding state when holding the substrate in the exposure apparatus, and substrate information including physical property values of the substrate material;
Using the substrate surface shape data B, information about the holding state, and the substrate information, it is possible to calculate transfer surface shape data C indicating the main surface shape of the substrate held in the exposure apparatus. , A calculation means for calculating drawing coordinate deviation amount data G at a plurality of points on the main surface using the thickness distribution data T and the transfer surface shape data C,
A drawing apparatus comprising: a drawing unit that draws on the photomask blank using the drawing coordinate shift amount data G and the pattern design data A.

(Configuration 13)
Among the deformations of the main surface that occur when the substrate is held in the exposure apparatus, a storage unit that stores the self-weight deformation amount data R indicating the deformation amount of the main surface due to the deflection of the substrate by its own weight is further included. Have,
The calculating means is characterized in that it calculates using the self-weight deformation amount data R,
The drawing device according to configuration 12.

(Configuration 14)
Regarding the coordinate deviation component peculiar to the drawing device, a storage means for storing the coordinate deviation peculiar data Q
The calculating means calculates using the coordinate deviation peculiar data Q,
The drawing device according to configuration 12 or 13.

(Structure 15)
In a photomask inspection method for inspecting a photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate using an inspection device,
The photomask, in a state of being placed on the stage of the inspection device, performing coordinate measurement of a pattern formed on the main surface, and obtaining pattern coordinate data L,
A step of preparing thickness distribution data T showing the thickness distribution of the substrate,
The step of obtaining the transfer surface shape data C showing the shape of the main surface when the photomask is held in an exposure device,
Using the thickness distribution data T and the transfer surface shape data C, a step of obtaining inspection difference data J,
Calculating a coordinate deviation amount at a plurality of points on the main surface corresponding to the inspection difference data J, and obtaining inspection coordinate deviation amount data K;
A method of inspecting a photomask, comprising an inspection step of inspecting the transfer pattern using the inspection coordinate shift amount data K and the pattern coordinate data L.

(Configuration 16)
In a photomask inspection method for inspecting a photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate using an inspection device,
The photomask, in a state of being placed on the stage of the inspection device, performing coordinate measurement of a pattern formed on the main surface, and obtaining pattern coordinate data L,
A step of preparing a thickness distribution data T showing the thickness distribution of the substrate, and a substrate surface shape data B showing the surface shape of the main surface,
When the photomask is held in the exposure apparatus, the displacement caused in the surface shape is reflected on the substrate surface shape data B, showing the shape of the main surface when held in the exposure apparatus, A step of obtaining the transfer surface shape data C,
Using the thickness distribution data T and the transfer surface shape data C, a step of obtaining inspection difference data J,
Calculating a coordinate deviation amount at a plurality of points on the main surface corresponding to the inspection difference data J, and obtaining inspection coordinate deviation amount data K;
A method of inspecting a photomask, comprising an inspection step of inspecting the transfer pattern using the inspection coordinate shift amount data K and the pattern coordinate data L.

(Configuration 17)
When the substrate is held in the exposure apparatus, of the deformation of the main surface, the self-weight deformation amount data R indicating the deformation amount of the main surface due to the self-weight deflection of the substrate is obtained,
17. In the step of obtaining the inspection difference data J, the thickness distribution data T, the transfer surface shape data C, and the self-weight deformation amount data R are used, and the inspection of the photomask according to configuration 15 or 16 is performed. Method.

(Structure 18)
Regarding the coordinate deviation component peculiar to the inspection device, the inspection coordinate deviation constant data S is obtained in advance,
In the inspection step, the inspection coordinate deviation amount data K and the pattern coordinate data L are used, and the inspection coordinate deviation constant data S is used for the inspection, and the inspection is performed. Photomask inspection method.

(Structure 19)
The photomask inspection method according to any one of Configurations 16 to 18, wherein a finite element method is used in the step of obtaining the transfer surface shape data C.

(Configuration 20)
The inspection of the transfer pattern is characterized in that the inspection coordinate deviation amount data K is reflected in the pattern design data A, and the correction design data M obtained and the pattern coordinate data L are used. 20. The photomask inspection method according to any one of Configurations 15 to 19.

(Configuration 21)
The inspection of the transfer pattern is performed by using the corrected coordinate data N and the pattern design data A obtained by reflecting the inspection coordinate displacement amount data K on the pattern coordinate data L. 20. The photomask inspection method according to any one of Configurations 15 to 19.

(Configuration 22)
A photomask blank in which a thin film and a photoresist film are formed on a main surface, which is used as a photomask by patterning the thin film.
A photomask manufacturing method, comprising the photomask inspection method according to any one of configurations 15 to 21.

(Configuration 23)
A method for manufacturing a display device, which comprises performing pattern transfer to a device substrate having a layer to be processed by exposing a photomask having a transfer pattern formed on a main surface thereof,
A method for manufacturing a display device, which uses a photomask manufactured by the manufacturing method according to any one of configurations 1 to 10.

(Configuration 24)
A method of manufacturing a display device including sequentially performing pattern transfer to a plurality of layers to be processed formed on a device substrate by using a plurality of photomasks each having a transfer pattern formed on each main surface and an exposure device. At
The method of manufacturing a display device, wherein the plurality of photomasks are manufactured by the manufacturing method according to any one of configurations 1 to 10.

(Configuration 25)
A photomask inspection apparatus for inspecting a photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate,
Performing coordinate measurement of the pattern formed on the main surface to obtain pattern coordinate data L, coordinate measuring means,
Pattern design data A of the transfer pattern,
Thickness distribution data T showing the thickness distribution of the substrate,
Transfer surface shape data C indicating the main surface shape of the substrate in a state where the substrate is held in the exposure device
Input means for inputting,
Using the thickness distribution data T, and the transfer surface shape data C, to calculate the inspection coordinate deviation amount data K at a plurality of points on the main surface, a calculating unit,
A photomask inspection device having an inspection means for inspecting the transfer pattern of the photomask by using the inspection coordinate shift amount data K and the pattern design data A.

(Configuration 26)
A photomask inspection apparatus for inspecting a photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate,
Performing coordinate measurement of the pattern formed on the main surface to obtain pattern coordinate data L, coordinate measuring means,
Pattern design data A of the transfer pattern,
The thickness distribution data T showing the thickness distribution of the substrate,
Showing the shape of the main surface of the substrate, substrate surface shape data B,
Information about a holding state when holding the substrate in the exposure apparatus, and substrate information including physical property values of the substrate material
Input means for inputting,
Using the substrate surface shape data B, information about the holding state, and the substrate information, it is possible to calculate transfer surface shape data C indicating the main surface shape of the substrate held in the exposure apparatus. The thickness distribution data T and the transfer surface shape data C are used to calculate inspection coordinate deviation amount data K at a plurality of points on the main surface,
A photomask inspection device having an inspection means for inspecting the transfer pattern of the photomask by using the inspection coordinate shift amount data K and the pattern design data A.

  According to the present invention, an efficient photomask manufacturing method, a drawing apparatus, a photomask inspection method, a photomask inspection apparatus, and a display capable of improving the coordinate accuracy of a pattern formed on a transfer target are provided. A method for manufacturing a device can be provided.

FIG. 1 (a) is a side view of a substrate held so that its main surface is vertical, and FIG. 1 (b) is a front view of the same substrate. FIG. 2 (a) is a cross-sectional view of the substrate in which a plurality of measurement points are set, and FIG. 2 (b) is a front view of the substrate. FIG. 3 (a) is a cross-sectional view of a mask model used in the finite element method, and FIG. 3 (b) is a front view of the mask model. FIG. 4 (a) is a sectional view of the mask model arranged so that the film surface is on the upper side, and FIG. 4 (b) is a sectional view of the mask model arranged so that the film surface is on the lower side. 4 (c) is a front view of the mask model arranged so that the film surface is on the upper side, and FIG. 4 (d) is a front view of the mask model arranged so that the film surface is on the lower side. is there. FIG. 5 (a) is a sectional view of a mask model showing the holding position by the holding member and the displacement received by the mask in the held state in the first embodiment. FIG. 5 (b) is a front view of the mask model of FIG. 5 (a) in the first embodiment, and the holding position by the holding member is shown by a dotted line. FIG. 6A is a sectional view showing an example of a force exerted on the mask held by the exposure apparatus in the first embodiment. FIG. 6 (b) is a diagram showing an example of a region to which a vacuum pressure is applied to the mask and a holding position of the holding member in the first embodiment. FIG. 6 is a schematic diagram of a hexahedron that constitutes a mask model in the first embodiment. In the first embodiment, after the transfer surface shape data C is obtained from the substrate surface shape data B, the drawing difference data F is obtained from the difference between the substrate thickness distribution data T and the transfer surface shape data C, and the drawing difference data F FIG. 7 is a schematic diagram showing steps from to obtaining drawing coordinate deviation amount data G. It is a schematic diagram for calculating the relationship between the shape variation of the film surface and the coordinate shift due to it. FIG. 6 is a schematic diagram showing a process from obtaining the inspection difference data J from the difference between the substrate thickness distribution data T and the transfer surface shape data C and then obtaining the inspection coordinate deviation amount data K from the inspection difference data J. FIG. 3 is a conceptual diagram of a drawing device used in the photomask manufacturing method according to the embodiment. It is the figure which expressed the coordinate shift of the measurement point resulting from the height of the substrate surface by a vector. FIG. 13A is a sectional view showing an example of the force exerted on the mask held by the exposure apparatus in the second embodiment. FIG. 13B is a diagram showing an example of the holding position of the holding member in the second embodiment. 9 is a schematic diagram showing a step of obtaining transfer surface correction data D from which a free flexure component is removed from the difference between the transfer surface shape data C and the reference shape data C1 reflecting the free flexure of the ideal substrate in the first embodiment. FIG. . In the second embodiment, a pattern showing a process of obtaining drawing difference data F from the difference between the substrate thickness distribution data T and the transfer surface correction data D, and obtaining drawing coordinate deviation amount data G from the drawing difference data F It is a figure. In the second embodiment, the inspection difference data J is obtained from the difference between the transfer surface correction data D excluding the self-weight deflection component and the substrate thickness distribution data T, and the inspection coordinate deviation amount data K is obtained from the inspection difference data J. It is a schematic diagram which shows the process of obtaining. 17A and 17C show the coordinate measurement results of the pattern drawn on the test photomask. 17 (b) and 17 (d) show the results of simulation of the coordinate shift when the test photomask is set in the exposure apparatus.

<Embodiment 1> (Drawing)
The photomask manufacturing method of the present invention has the following steps.

Preparation of Photomask Blank In the present invention, a photomask blank is formed by forming a pattern designed based on a device to be obtained on a photomask blank having a main surface of a substrate and one or more thin films and a photoresist film formed thereon. Draw to make Therefore, a photomask blank in which the thin film and the photoresist film are formed on one main surface of the substrate is prepared.

A known photomask blank can be used.
A transparent substrate such as quartz glass can be used as the substrate. The size and thickness are not limited, but those used for manufacturing a display device having a side of 300 mm to 1800 mm and a thickness of 5 to 15 mm can be used.

  In the present application, in addition to the substrate before the thin film is formed, a substrate having one or more thin films formed on the main surface or a substrate having a photoresist film formed on the thin film is referred to as a “substrate” (or a photomask blank). Substrate, photomask substrate).

  In the process of measuring the flatness and thickness distribution (hereinafter also referred to as TTV (total thickness variation)) of the main surface of the substrate, the influence of the thickness of the thin film or photoresist film formed on the main surface is substantially Does not occur. This is because the film thickness of the thin film or the photoresist film is sufficiently small and does not substantially affect the above measurement.

  As a thin film, in addition to a light-shielding film (optical density OD = 3 or more) that blocks exposure light when using a photomask, a semi-transmissive film that partially transmits exposure light (exposure light transmittance is 2 ~ 80%) or a phase shift film (for example, an exposure light having a phase shift amount of 150 to 210 degrees and an exposure light transmittance of about 2 to 30%) or controlling the light reflectivity. It may be an optical film such as an antireflection film. Further, a functional film such as an etching stopper film may be included. It may be a single film or a laminated film of a plurality of films. For example, a light-shielding film containing Cr, an antireflection film, a semi-transparent film containing Cr compound or metal silicide, a phase shift film, and the like can be applied. It is also possible to apply a photomask blank in which a plurality of thin films are laminated. By applying the method of the present invention to the patterning of each of the plurality of thin films, a photomask having excellent transferability with excellent coordinate accuracy can be obtained.

  The photoresist formed on the outermost surface may be a positive type or a negative type. A positive type is useful as a photomask for a display device.

I Process of preparing pattern design data A The pattern design data is data of a transfer pattern designed based on a device (display device or the like) to be obtained.

  There are no restrictions on the application of the device manufactured by the photomask according to the present invention. For example, by applying the present invention to each layer of each constituent of the liquid crystal display device or the organic EL display device, excellent effects can be obtained. For example, a line-and-space pattern with a pitch of less than 7 μm (such as a line or space with a line width (CD: Critical Dimension) of 4 μm or a portion of less than 3 μm) or a diameter of 1.5 to 5 μm, especially 1.5 to 3.5 μm INDUSTRIAL APPLICABILITY The present invention is advantageously used for a photomask for a finely designed display device having a hole pattern, etc.

  When the pattern design data is used as it is without being corrected for drawing, the film surface shape at the time of drawing (when placed in the drawing apparatus) and at the time of exposure (when held in the exposure apparatus) Due to the difference, the coordinate accuracy becomes insufficient when the transfer pattern is formed on the transfer target. Therefore, the correction is performed by the following steps.

II Process of obtaining the thickness distribution data T showing the thickness distribution of the substrate and the substrate surface shape data B The order of acquiring the thickness distribution data T and the substrate surface shape data B may be either first, or in separate steps Alternatively, it may be acquired in one step. Here, the case where the same flatness measuring device is used to perform the measurement in one step will be exemplified.
For example, the substrate to be measured is held so that the main surface is substantially vertical. That is, it can be measured by a flatness measuring device in a state where the deflection due to its own weight does not substantially affect the shapes of the front and back surfaces of the substrate (see FIG. 1).
The measurement can be performed by a flatness measuring device using an optical measuring method such as detecting reflected light of irradiated light (laser or the like). Examples of the measuring device include flatness measuring machine FTT series manufactured by Kuroda Seiko Co., Ltd., and those described in JP-A-2007-46946.
At this time, set a plurality of intersections (lattice points) of the grid drawn in the XY direction at equal intervals on the main surface (with the spacing P as the pitch P) and set them as measurement points. (See Figure 2).

  For example, a flatness measurement that has a function of measuring the distance in the Z direction (see Fig. 2) between the reference plane and each of the above measurement points as a reference plane. Machine can be used. By this measurement, the flatness of the main surface of the substrate can be grasped, and thereby the substrate surface shape data B can be obtained. FIG. 2 shows an example in which P is 10 mm.

  As shown in FIG. 2 (a), the heights in the Z direction of all measurement points on the main surface are measured. As a result, the substrate surface shape data B is obtained in the form of a flatness map (see FIG. 8 (a)).

  In addition, when acquiring the substrate surface shape data B, the measurement point is set at a position corresponding to the film surface side on the substrate back surface side (the surface opposite to the main surface which is the film surface), and the same measurement is performed. By performing the above, it is possible to obtain the substrate backside shape data and the substrate thickness (distance between the film surface and the backside) distribution data T at each measurement point (see FIG. 2 (a)). The thickness distribution of the substrate is also referred to as TTV (Total thickness variation). This thickness distribution data T can be used later.

  Regarding the setting of the measurement point, the separation distance P can be determined from the viewpoint of measurement time depending on the size of the substrate and the viewpoint of correction accuracy. The separation distance P can be, for example, 2 ≦ P ≦ 20 (mm), and more preferably 5 ≦ P ≦ 15 (mm).

  Moreover, after the surface flatness on the film surface side is measured, the least squares plane can be obtained from the measured value. The origin O is the center of this plane.

III Step of Obtaining Transfer Surface Shape Data C Next, when this substrate becomes a photomask, consider a state in which the photomask is held in the exposure apparatus. The photomask set in the exposure device is held with the film surface facing downward. In this state, the film surface (transfer surface) of the substrate receives a force depending on the holding state, and its shape changes. This results in different deformation depending on the shape of the holding member.

III-1 method <1>
Here, a case will be described in which an exposure apparatus that holds a mask substrate is used by the method shown in FIGS.
In the exposure device, the mask substrate is supported substantially horizontally with the film surface side (pattern formation surface) facing downward, and is held by contacting the holding member in the vicinity of the outer edge.

  The substrate held substantially horizontally is bent by its own weight, and the position near the center of the main plane is lower than the position near the outer edge. Therefore, in order to counter the self-weight of the photomask and reduce the deflection, a predetermined area may be set on the back surface (the surface opposite to the film surface side) of the photomask, and a force due to vacuum pressure may be applied to the area. Yes (Figure 6b)). In this case, the force received by the photomask changes depending on the area and the magnitude of the vacuum pressure. Here, the case of exerting a vacuum pressure refers to a state in which the space on the back surface of the photomask transfer surface is depressurized to suck the photomask upward.

  The substrate surface shape (transfer surface shape) can be measured under such a force. That is, by providing the required number of measurement points on the photomask film surface set in the exposure machine and measuring the shape by an optical means or the like, for example, a map as shown in FIG. 10 (b) can be obtained. it can. This measurement point is preferably the same position as the measurement point used in the substrate surface shape data B.

However, the present invention can be carried out without performing measurement.
For example, the displacement generated on the photomask film surface held in the exposure apparatus is calculated, and this is reflected on the substrate surface shape data B to obtain the transfer surface shape data C (FIG. 8 ((( (See b)), that is, using the information about the holding state (including the holding condition by the holding member and the vacuum pressure condition against the own weight) that affects the main plane shape when held in the exposure apparatus, The transfer surface shape data C can be obtained by simulation.

  In this step, it is preferable to apply the finite element method. Therefore, as a preparatory step, a mask model is created (Fig. 3).

  By the above-described flatness measurement of the film surface side and the back surface side, the shape data of both surfaces are obtained. Here, with respect to the outermost measurement point, one more virtual measurement point is added at a position separated by one pitch on the substrate end side, and the height in the Z direction of this virtual measurement point is set to the outermost circumference. Set the same height as the measurement point of. This is to correctly reflect the size and weight of the substrate in the finite element method used below. Also, a virtual measurement point is set in the middle of the corresponding measurement points on the film surface side and the back surface side, and the median value of the two corresponding measurement values is set. Then, adjacent measurement points (including virtual measurement points) are connected by a straight line (see FIGS. 3 (a) and 3 (b)).

  The virtual measurement points are not limited to being provided at the center of the measured values on the film surface and the back surface, and two or three points may be provided at equal intervals in the thickness direction.

  4 (a) to 4 (d) are schematic views of this mask model as seen from both the front and back sides and the cross section.

  Next, in this mask model, a plurality of holding points at which the photomask is held by the holding member in the exposure apparatus are set. This is the point that when the photomask is mounted in the exposure apparatus, it is held by the holding member or held and constrained by suction, and it depends on the manufacturer, generation, and size of the exposure apparatus. Make a decision based on

In this aspect, as an example, a rectangular band-shaped holding member arranged in the vicinity of four sides forming the outer periphery of the main surface of the substrate in parallel with the four sides and separated from the outer periphery by a predetermined distance forms a transfer pattern formation region. A case where the film surface side of the substrate is contacted so as to surround it will be described (dotted line in FIG. 5B).
That is, in the models shown in FIGS. 6 (a) and 6 (b), the measurement points on the dotted line are the holding points. In the exposure apparatus, the holding point is displaced by coming into contact with and restrained by the holding member, which may cause the entire film surface shape to be displaced due to the physical properties of the substrate.
Further, as described above, since the substrate is subjected to its own weight and is bent, an upward force for reducing the bending is applied. This is done by applying a vacuum pressure from above the substrate (back side). (Figure 6 (a)). The region exerting the vacuum pressure can be a rectangular region including the center of the main surface of the substrate, as shown in FIG. 6 (b).

In the model shown in FIG. 5 (a), the forced displacement amount is set so that the position of the measurement point, which is the holding point, becomes zero on the Z axis. The zero position in the Z-axis direction refers to the already set least-squares plane (and the origin on it). For example, when the value of the flatness on the film surface side of a certain measurement point which is the holding point is 5 μm, the amount of forced displacement at that measurement point is “−5 μm”.
Here, the amount of vacuum pressure applied from the back surface side is preferably set to an amount that minimizes the flatness of the film surface.
When evaluating the flatness of a given surface, the maximum value of the distance between the given surface and the reference surface (often the reference surface is almost parallel to the given surface) It may be expressed as the difference between the minimum values. That is, when the value of the flatness is small, it means that the surface has less unevenness and is flatter.

  Therefore, in order to determine the amount of vacuum pressure applied to the simulation, the vacuum pressure at which the flatness of the film surface becomes minimum when the vacuum pressure applied to the back surface of the photomask substrate is changed may be obtained. Generally, the displacement of the substrate due to its own weight deflection is maximum near the center of the substrate, so the distance from the reference plane at the center point of the film surface (substrate main surface) is the distance from the reference surface at the outer edge of the substrate, When closest, the flatness is considered to be minimal. In measuring the distance from the reference plane at the outer edge of the substrate, a plurality of measurement points may be set on the outer edge, or a specific position may be set as a representative point. Further, the vacuum pressure at which the film surface flatness becomes the minimum may be set by actually setting the substrate in the exposure apparatus and actually measured, or may be obtained as a part of a simulation using the above information on the holding state. .

  Next, the model conditions prepared above are input to software of the finite element method (FEM), and the displacement of each measurement point other than the holding point is calculated by the forced displacement. As a result, “transfer surface shape data C” indicating the film surface shape of the photomask in the exposure apparatus can be obtained.

When applying the finite element method, various physical property values and parameters of conditions are required. In this aspect, the following is taken as an example.
[Substrate (quartz glass) physical property condition]
Young's modulus E: 7341 kg / mm ^ 2
Poisson's ratio ν: 0.17
Weight density m: 0.0000022 kg / mm ^ 3
[Mask Model condition]
Coordinate value (x, y, z) file of each measurement point: (for all measurement points of film surface, back surface, and intermediate point)
Condition file connecting measurement points: hexahedron In this aspect, regarding the corresponding measurement points on the film surface and the back surface, and their intermediate points (including virtual measurement points), a model in which hexahedrons are accumulated by connecting all adjacent objects (See Figure 7).
[Retention condition]
File with forced displacement set: Forced displacement at the above holding point [vacuum pressure condition]
File that sets the amount of vacuum pressure and the area that exerts it

Then, the finite element method is used to calculate the displacement amounts of all measurement points other than the holding point.
The photomask held in the exposure apparatus is stationary due to the balance of the forces acting on it. At this time,
Weight vector G − Stress vector σ − Vacuum pressure vector = 0
Has been established.

here,
Stress vector σ ＝ [k] × displacement vector u
(However, [k] is a matrix composed of Young's modulus e and Poisson's ratio ν)
Gravity vector G = Element volume x Weight density m x Gravity direction vector.

Here, each element is an individual hexahedron as shown in FIG.
For all elements (entire board)
G1−σ1−F1 + G2−σ2−F2 + G3−σ3−F3 + ・ ・ ・ = 0 (Equation <1>)
G1-F1 + G2-F2 + G3-F3 + ... = σ1 + σ2 + σ3 + ・ ・ ・ ＝ [k1] u1 ＋ [k2] u2 ＋ [k3] u3 + ・ ・ ・ (Equation <2>)

  Here, the displacement amount vector (u1, u2, u3, ...) Becomes the displacement amount at each measurement point and is a numerical value to be obtained. However, the displacement amount vector at the holding point is input as the forced displacement amount as described above.

  Data on the film surface shape of the photomask held in the exposure apparatus can be obtained from the displacement amount vector of each measurement point calculated by the finite element method. That is, this is the data of the film surface shape of the photomask when the pattern is transferred by the exposure device, and is “transfer surface shape data C”.

III-2 method <2>
The method <2> uses the model in FIG.
Here, as shown in FIG. 13 (b), the holding member of the exposure apparatus is in contact with the vicinity of two opposing sides on the main surface of the mask substrate (measurement points on the dotted line in FIG. 13 (b)). Is the holding point). Then, the photomask is held with the film surface side facing downward. In the main plane of the photomask substrate in the exposure machine, this holding point is constrained by the holding member and forcibly displaced, whereby the physical properties of the substrate cause the entire film surface shape to be displaced.

  In the model shown in FIG. 13 (a), the forced displacement amount is set so that the position of the measurement point, which is the holding point, becomes zero on the Z axis. The zero position in the Z-axis direction refers to the already set least-squares plane (and the origin on it). For example, when the value of the flatness on the film surface side of a certain measurement point which is the holding point is 5 μm, the amount of forced displacement at that measurement point is “−5 μm”.

  Next, the model conditions prepared above are input to software of the finite element method (FEM), and the displacement of each measurement point other than the holding point is calculated by the forced displacement. As a result, “transfer surface shape data C” indicating the film surface shape of the photomask in the exposure apparatus can be obtained. The transfer surface shape data C includes a flexure component due to gravity (see FIG. 14 (b)).

  When applying the finite element method, various physical property values and parameters of conditions are required. However, in this method, the vacuum pressure is not applied to the mask substrate set in the exposure apparatus. Therefore, the file that sets the vacuum pressure condition in the above method <1> is unnecessary.

Here again, each element is an individual hexahedron, as shown in FIG.
The sum of all six elements (entire board) is
G1--σ1 + G2--σ2 + G3--σ3 + ... = 0 (Equation <3>)
G1 ＋ G2 ＋ G3 ＋ ・ ・ ・ ＝ σ1 ＋ σ2 ＋ σ3 ＋ ・ ・ ・ ＝ [k1] u1 ＋ [k2] u2 ＋ [k3] u3 ＋ ・ ・ ・ (Formula <4>)

  Here, the displacement amount vector (u1, u2, u3, ...) Becomes the displacement amount at each measurement point and is a numerical value to be obtained. However, the displacement amount vector at the holding point is input as the forced displacement amount as described above.

  Data on the film surface shape of the photomask held in the exposure apparatus can be obtained from the displacement amount vector of each measurement point calculated by the finite element method. That is, this is the data of the film surface shape of the photomask when the pattern is transferred by the exposure device, and is “transfer surface shape data C”.

Step of Obtaining Transfer Surface Correction Data D The transfer surface shape data C includes the influence of bending due to gravity acting on the substrate. On the other hand, the deformation of the film surface shape due to the deflection due to its own weight and the amount of deviation of each coordinate position due to the deformation can be calculated relatively easily if the physical property value derived from the size of the substrate and the material is given. Is possible. For this reason, some exposure apparatuses used for manufacturing masks for display devices are provided with a function of correcting the coordinate shift caused by the self-weight deflection component. In this case, the self-weight deflection component is compensated. Is drawn.

  Therefore, in order to obtain the drawing correction pattern data, the gravity deflection component should be removed from the "transfer surface shape data C" so as not to perform the correction by the compensation function of the gravity deflection component provided in the exposure apparatus and the overlap correction. Is required. Therefore, from the transfer surface shape data C, transfer surface correction data D from which the deformation due to the self-weight deflection of the substrate, that is, the self-weight deflection component is removed is obtained (FIG. 14 (e)).

  For this reason, the deformation component due to the self-weight deflection (self-weight deflection component) is calculated. That is, for a substrate (also referred to as an ideal substrate) having the same material, shape, and size as the above-described substrate and having an ideal shape (the main planes are parallel to each other), deformation of the main surface due to gravity deflection alone is obtained. (Fig. 14 (d)). This is also referred to as reference shape data C1. The finite element method can be applied here as in the above case.

Alternatively, instead of obtaining the gravitational deflection component of the virtual ideal substrate, a predetermined reference substrate may be prepared and the deformation due to its own weight deflection may be obtained by the procedure of the finite element method. The reference shape data C2 obtained in this case may be used instead of C1. This method can be applied when the specification of the reference substrate is defined for a specific exposure apparatus.
This C1 or C2 is equivalent to the self-weight deformation amount data R indicating the deformation amount of the main surface due to the self-weight deflection of the substrate among the deformations of the main surface that occur when the substrate is held in the exposure apparatus. To do.

  Then, the transfer surface correction data D can be obtained by subtracting C1 (or C2) from the already acquired transfer surface shape data C to obtain the difference. (Fig. 14 (e))

IV Step of obtaining drawing difference data F As described above, when a pattern is drawn on the photomask blank by the drawing device, the photomask blank is placed on the stage of the drawing device with the film surface facing upward. . At that time, the deformation factor of the surface shape of the film surface of the photomask blank from the ideal plane is
(1) Insufficient flatness of the stage,
(2) Deflection of the substrate due to the inclusion of foreign matter on the stage,
(3) Asperity on the film surface of the photomask blank,
(4) Deformation of the film surface due to unevenness on the back surface of the photomask blank,
It is thought that there is. Therefore, the surface shape of the photomask blank in this state is formed by accumulating the above four factors. Then, drawing is performed on the photomask blank in this state.

  On the other hand, in the photomask which has been patterned after drawing and set in the exposure apparatus, the deformation factors due to (1), (2), and (4) have disappeared from the main surface thereof. It is necessary to quantify the coordinate shift due to this shape change.

  Here, the above (1) is unique to the stage of the drawing apparatus, and is a coordinate shift element that occurs reproducibly as long as the same stage is used. Therefore, the stage surface shape of the drawing apparatus is precisely measured in advance and held as a parameter, which can be used when obtaining drawing difference data F described later. This parameter is, for example, coordinate deviation specific data Q.

  Further, the above item (2) is an accidental coordinate shift factor, and the occurrence probability is not large. Furthermore, in order to further reduce the occurrence of coordinate deviation due to this factor, the presence of foreign matter can be eliminated as much as possible by performing the stage cleaning process more strictly.

  In other words, the height variation on the drawing stage due to the above (3) + (4) can be expressed as (3) + (substrate thickness variation). That is, of the factors that affect the coordinate shift, the data correction can be performed for the value (4) using the numerical value of the thickness distribution data T.

  Therefore, in the present invention, it is possible to carry out the step of obtaining the drawing difference data F by using the thickness distribution data T and the transfer surface shape data C which are obtained in advance.

For method <1> (Fig. 8):
As shown in FIG. 8, the difference between the transfer surface shape data C and the thickness distribution data T is obtained. Preferably, the drawing difference data F is obtained by further subtracting the coordinate deviation specific data Q indicating the coordinate deviation element unique to the drawing apparatus such as the stage surface flatness from the difference obtained here. The coordinate deviation specific data Q may be converted into the XY coordinate value as the coordinate deviation amount and then reflected on the drawing coordinate deviation amount data G.

For method <2> (Figs. 14 and 15)
As shown in FIG. 15, the drawing difference data F is obtained by obtaining the difference between the transfer surface correction data D and the thickness distribution data T. Preferably, the coordinate difference specific data Q is further subtracted from the difference obtained here to obtain the drawing difference data F. The coordinate deviation specific data Q may be converted into the XY coordinate value as the coordinate deviation amount and then reflected on the drawing coordinate deviation amount data G.

On the other hand, the factors of deformation of the photomask film surface held in the exposure apparatus from the ideal plane are
(5) Concavity and convexity on the photomask film surface (substantially the same as the above (3))
(6) Deformation of the film surface that is forced by being held by the photomask holding member (7) Deflection due to its own weight (when vacuum pressure is applied to reduce this, deformation in the opposite direction)
Will be accumulated.

  Therefore, it can be said that the difference between the two film surface shapes should be applied to the correction of the “pattern design data A” because it is a factor that causes a coordinate shift due to transfer. This is the drawing difference data F.

V Process of obtaining coordinate deviation amount data G for drawing The drawing difference data F is converted into a displacement (coordinate deviation amount) on the XY coordinates. For example, it can be converted by the following method (see FIG. 9).

  FIG. 9 is an enlarged view of a cross section of the substrate 13 on the stage 10 of the drawing apparatus. The thin film 14 is omitted. The shape of the surface 20 of the substrate 13 arranged on the stage 10 is deformed from the ideal plane due to a plurality of factors as described above.

Here, when the height at the measurement point adjacent to the measurement point having the height of 0 (that is, the measurement point whose height matches the reference surface 21) is H, the difference between the height and the surface 20 of the substrate 13 The angle Φ formed by the reference surface 21 is
sinΦ = H / Pitch (Equation 1)
(Pitch: Distance between measurement points, that is, distance P between adjacent measurement points)
Is represented by In the above, H / Pitch can be considered as a gradient in the height direction of the substrate surface.

If the value of Φ is small enough,
Φ = H / Pitch (Equation 1 ')
Can also be approximated. In the following description, (Equation 1) is used.

In the above case, the displacement d in the X-axis direction of the measurement point due to this difference in height is
d = sinΦ × t / 2 = H × (t / 2Pitch) (Equation 2)
Can be obtained by

Even in the above, if Φ is sufficiently small,
d = Φ × t / 2 = H × (t / 2Pitch) (Equation 2 ′)
Can also be approximated.
Alternatively, the coordinate shift amount of the measurement point due to the difference in height can be calculated by a method using a vector. FIG. 12 is a diagram in which the coordinate shift of the measurement point due to the difference in height is represented by a vector. In the drawing height distribution data E, consider an inclined surface made from three arbitrary measurement points. At this time, the deviation ΔX in the X-axis direction from the inclined surface and the deviation ΔY in the Y-axis direction from the inclined surface are expressed by the following equations.
ΔX = t / 2 × cos θx
ΔY = t / 2 × cos θy (Equation 3)
Two tilt vectors can be created from arbitrary three measurement points. A normal vector for the inclined surface is created from the cross product calculation of these two inclination vectors.
Further, cos θx is calculated from the inner product calculation of the normal vector and the X-axis unit vector, and cos θy is calculated from the inner product calculation of the normal vector and the Y-axis unit vector.
By substituting the calculated cos θx and cos θy into (Equation 3), the deviation ΔX in the X-axis direction and the deviation ΔY in the Y-axis direction can be finally calculated.

  Here, t is the thickness of the substrate. The thickness t at each measurement point is included in the TTV already acquired above.

  Therefore, in this embodiment, the transfer surface shape data C (in the method <2>, the transfer surface correction data D obtained by subtracting the gravity deflection component from the transfer surface shape data C in the method <2>) and the thickness distribution data T at all measurement points on the substrate 13. The drawing coordinate difference amount data G can be obtained by obtaining the height corresponding to the difference and calculating the coordinate difference amount in the X direction and the Y direction for the obtained drawing difference data F. . Of course, the calculation method is not limited to the above unless the effects of the invention are impaired.

VI Drawing Step of Drawing Correction Pattern Data H The correction pattern data H is drawn using the drawing coordinate deviation amount data G and “pattern design data A” obtained above.
At this time, the pattern design data A may be corrected based on the drawing coordinate shift amount data G to obtain drawing correction pattern data H (not shown), and drawing may be performed based on the drawing correction pattern data H.

  When correcting the pattern design data A, the drawing coordinate deviation amount data G obtained for each measurement point may be processed and used. For example, the drawing coordinate deviation amount data G may be reflected in the pattern design data A after the data of each measurement point is interpolated using the least squares method or is standardized by a predetermined rule.

Alternatively, the coordinate system of the drawing device may be corrected based on the drawing coordinate shift amount data G, and drawing may be performed using the obtained corrected coordinate system and the “pattern design data A”. This is because many drawing devices have a drawing function based on the corrected coordinates after given a predetermined correction to the coordinate system of the drawing device.
The drawing coordinate shift amount data G used at this time can be processed in the same manner as described above.

The drawing method according to the present invention is not limited to the above aspect.
At the time of drawing, a mark pattern or the like may be appropriately added outside the transfer pattern area. As described later, a mark pattern for coordinate measurement can be additionally drawn here.

For example, the shape of the holding member of the exposure apparatus may differ depending on the apparatus, as described above.
In the method <1>, the exposure apparatus provided with four linear holding members along the four sides of the substrate is illustrated.
In the method <2>, the case where the holding members arranged in parallel near the two opposite sides of the substrate contact the film surface side of the substrate has been described.

  However, the present invention can be applied to a device having another member shape. This may be performed by appropriately changing the model condition at the time of calculation of the finite element method, the holding condition, and the vacuum pressure condition if necessary.

  Further, in the above aspect, the holding point at which the photomask is held by the holding member is constrained on the plane (least square plane of the substrate film surface). This is because the holding member holds the photomask on a single plane. However, if the holding point does not lie on a single plane due to the shape of the holding member, the shape of the holding member may be reflected when setting the forced displacement amount in the step of obtaining the transfer surface shape data C. .

  The order of the steps may be changed as long as the effects of the present invention are not impaired. Further, when the result does not change even if the order of the operations is changed, it is a matter of course that the present invention includes the result.

  After the corrected pattern data is drawn on the photomask blank by the drawing method of the above aspect, the photomask is manufactured by the patterning process.

About the patterning process The photomask blank (photomask intermediate) on which drawing has been performed becomes a photomask through the following steps.
A known method can be applied to the patterning process. That is, the drawn resist film is developed with a known developing solution to form a resist pattern. The thin film can be etched by using this resist pattern as an etching mask.
A known etching method can be used. Either dry etching or wet etching may be applied. Since the present invention is particularly useful as a method for manufacturing a photomask for a display device, the effects of the present invention can be remarkably obtained when wet etching is applied.

  In the drawing step of the present invention described above, the drawing target is not only a photomask blank (one in which the transfer pattern is not drawn) but also a plurality of thin films It may be a patterned photomask intermediate.

  For a photomask blank including a plurality of thin films, the drawing process of the present invention described above can be applied to the drawing process for patterning each thin film. In this case, it is extremely advantageous in that a highly accurate photomask having excellent overlay accuracy can be manufactured.

Drawing Device The present application includes an invention relating to a drawing device capable of carrying out the above-described drawing method.
That is, the drawing device is a drawing device used for drawing a transfer pattern on a photomask blank in which a thin film and a photoresist film are formed on the main surface of a substrate.
The drawing device includes the following means.

Input means Input means
Pattern design data A of the transfer pattern,
Thickness distribution data T indicating the thickness distribution of the substrate, and transfer surface shape data C indicating the main surface shape of the substrate in a state where the substrate is held by an exposure device.
Is a means for enabling input.

Calculating means The calculating means uses the thickness distribution data T and the transfer surface shape data C to calculate the drawing coordinate deviation amount data G at a plurality of points on the main surface.

Then, the drawing apparatus has a drawing means for drawing on the photomask blank using the drawing coordinate shift amount data G and the pattern design data A.
Furthermore, the drawing apparatus of the present invention may include the following means.

Input means Input means
Pattern design data A of the transfer pattern,
Thickness distribution data T showing the thickness distribution of the substrate, and showing the shape of the main surface of the substrate, substrate surface shape data B,
It is a means for inputting information about a holding state when holding the substrate in the exposure apparatus and substrate information including physical property values of the substrate material.

Calculating means The calculating means uses the substrate surface shape data B, the information regarding the holding state, and the substrate information to indicate the main surface shape of the substrate held in the exposure apparatus. A means capable of calculating C, and by using the thickness distribution data T and the transfer surface shape data C, it is possible to calculate drawing coordinate deviation amount data G at a plurality of points on the main surface. . As the calculation means, for example, a known calculation device such as a personal computer can be used.

Drawing means Drawing means is means for drawing on the photomask blank using the drawing coordinate shift amount data G and the pattern design data A.

  In addition, it is preferable to include a control unit that controls the input unit, the calculation unit, and the drawing unit.

  Here, the information regarding the holding state is, for example, the holding condition (the shape of the holding member, or the coordinates of the substrate holding point at which the substrate comes into contact with the holding member when the substrate is held in the exposure apparatus (according to the information of the coordinate. , The amount of forced displacement of the holding point can be calculated), and when vacuum pressure is used, it is preferable to include a vacuum pressure condition (amount of vacuum pressure and a region to be applied).

  The substrate information can be, for example, Young's modulus, Poisson's ratio, and weight density of the substrate.

  By using such a drawing apparatus, it is possible to carry out the drawing process necessary for the photomask manufacturing method described above.

<Embodiment 2> (Inspection)
As described above, according to the present invention, it is possible to obtain a photomask that can make the coordinate accuracy of a pattern formed on a workpiece extremely high.
By the way, when inspecting such a photomask before shipping, it is necessary to perform an inspection in consideration of a difference between the photomask placed in the inspection apparatus and the photomask held in the exposure apparatus. Most desirable.
Therefore, the need for a new inspection method was found by the inventor.

VII Step of obtaining pattern coordinate data L The photomask on which the pattern has been formed is placed on the stage of the coordinate inspection device with the film surface (pattern formation surface) facing upward, and the coordinates are measured. The data obtained here is referred to as pattern coordinate data L.
Here, the coordinate measurement is preferably performed by measuring the coordinates of a mark pattern formed on the main surface of the photomask in advance at the same time as the transfer pattern. This mark pattern is preferably provided on the main surface at a plurality of positions outside the area of the transfer pattern.

VIII Step of preparing thickness distribution data T indicating the thickness distribution of the substrate The thickness distribution data T can be obtained in the same manner as the step described in II of the first embodiment.

IX Step of Obtaining Transfer Surface Shape Data C The transfer surface shape data C can be obtained in the same manner as the step described in III of the first embodiment.

Step of Obtaining X Inspection Difference Data J The inspection difference data J is obtained by obtaining the difference between the thickness distribution data T and the transfer surface shape data C (see FIGS. 10 (a) to 10 (d)).
Preferably, the inspection coordinate deviation constant data S, which is a coordinate deviation component peculiar to the inspection apparatus such as the flatness of the stage surface, is further reduced with respect to the difference obtained here.

XI Process of obtaining inspection coordinate deviation amount data K Calculate the coordinate deviation amount at a plurality of points on the main surface corresponding to the inspection difference data J to obtain the inspection coordinate deviation amount data K (Fig. 10 (d )-(E)). Here, the step of converting the height difference into the coordinate shift amount can be performed in the same manner as the step V described above.

Then, using the obtained inspection coordinate shift amount data K and the pattern coordinate data L, the transfer pattern is inspected.
Specifically, in the inspection of the transfer pattern, the inspection coordinate deviation amount data K is reflected in the pattern design data A, and the obtained corrected design data M and the pattern coordinate data L are used (compared with each other. You can do it.
Alternatively, in the inspection of the transfer pattern, the inspection coordinate deviation amount data K is reflected in the pattern coordinate data L, and the obtained corrected coordinate data N and the pattern design data A are used (compared with each other). You can also do it.

  The photomask manufactured by the manufacturing method of the present invention is preferably inspected by the inspection method of the present invention.

There are no restrictions on the use of the photomask, and there is no restriction on its configuration.
It is obvious that the photomask having any film structure such as a so-called binary mask, multi-tone mask, phase shift mask, or the like can provide the operation and effect of the present invention.

Inspection Device The present invention includes an invention relating to an inspection device capable of implementing the above-described inspection method.
That is,
A photomask inspection apparatus for inspecting a photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate,
Performing coordinate measurement of the pattern formed on the main surface to obtain pattern coordinate data L, coordinate measuring means,
Pattern design data A of the transfer pattern,
Thickness distribution data T showing the thickness distribution of the substrate,
Transfer surface shape data C indicating the main surface shape of the substrate in a state where the substrate is held in the exposure device
Input means for inputting,
Using the thickness distribution data T, and the transfer surface shape data C, to calculate the inspection coordinate deviation amount data K at a plurality of points on the main surface, a calculating unit,
A photomask inspection device having an inspection means for inspecting the transfer pattern of the photomask by using the inspection coordinate shift amount data K and the pattern design data A.

Furthermore, the present invention includes the following inspection device.
A photomask inspection apparatus for inspecting a photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate,
Performing coordinate measurement of the pattern formed on the main surface to obtain pattern coordinate data L, coordinate measuring means,
Pattern design data A of the transfer pattern,
The thickness distribution data T showing the thickness distribution of the substrate,
Showing the shape of the main surface of the substrate, substrate surface shape data B,
Input means for inputting information about a holding state when holding the substrate in the exposure apparatus, and substrate information including physical property values of the substrate material;
Using the substrate surface shape data B, information about the holding state, and the substrate information, it is possible to calculate transfer surface shape data C indicating the main surface shape of the substrate held in the exposure apparatus. The thickness distribution data T and the transfer surface shape data C are used to calculate inspection coordinate deviation amount data K at a plurality of points on the main surface,
A photomask inspection device having an inspection means for inspecting the transfer pattern of the photomask by using the inspection coordinate shift amount data K and the pattern design data A.

  The information regarding the holding state when holding the substrate in the exposure apparatus and the substrate information including the physical property values of the substrate material are as described above.

  Calculating the transfer surface shape data C indicating the main surface shape of the substrate held in the exposure apparatus means an operation for performing the same steps as the steps III-1 to III-2 described above. To do.

  Using the inspection coordinate deviation amount data K and the pattern design data A, when inspecting the transfer pattern of the photomask, the comparison necessary for the step XI (for comparison if necessary Calculation).

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a display device, which comprises performing pattern transfer on a device substrate having a layer to be processed by exposing a photomask having a transfer pattern formed on a main surface thereof. In the method of manufacturing a display device, the photomask according to the manufacturing method of the present invention is used.

  That is, using a photomask according to the manufacturing method of the present invention, and when manufacturing the photomask, the conditions for the state held in the exposure apparatus are determined. Exposure is performed using the exposure apparatus, pattern transfer It is a manufacturing method of a display device to which the method is applied. The pattern transferred to the object to be processed by the pattern transfer becomes a display device by being subjected to processing such as etching.

Here, the effects of the present invention are remarkable when the optical performance of the exposure apparatus is, for example, as follows.
It is an exposure device of 1x exposure used for LCD (or FPD, liquid crystal), and its configuration is
The numerical aperture (NA) of the optical system is 0.08 to 0.15 (especially 0.08 to 0.10),
Coherence factor (σ) is 0.5 to 0.9,
The exposure wavelength is preferably exposure light having a representative wavelength of any one of i-line, h-line and g-line, and particularly a broad wavelength light source including all i-line, h-line and g-line.
When applying a vacuum pressure, it is preferable to apply the vacuum pressure applied in the finite element method when setting the photomask in the exposure apparatus.

  The layer to be processed refers to each layer that becomes a constituent of a desired electronic device through a process such as etching after transferring a transfer pattern of a photomask. For example, in the case of forming a TFT (thin film transistor) circuit for driving a liquid crystal display device or an organic EL display device, a pixel layer, a source / drain layer, etc. are exemplified.

  The device substrate refers to a substrate having a circuit which is a constituent of an electronic device to be obtained, such as a liquid crystal panel substrate or an organic EL panel substrate.

  Furthermore, the present invention uses the above-mentioned exposure apparatus and a plurality of photomasks each having a transfer pattern formed on its main surface, and sequentially performs pattern transfer to a plurality of layers to be processed formed on a device substrate. A method of manufacturing a display device including: using a photomask manufactured by the manufacturing method of the present invention.

  The display device manufactured by applying the present invention has extremely high overlay accuracy of each layer constituting the display device. Therefore, the manufacturing yield of the display device is high and the manufacturing efficiency is high.

[Example]
The effect of the invention by the photomask manufacturing method (drawing step) of the present invention will be described with reference to the schematic diagram shown in FIG.
Here, when the transfer pattern is drawn on a substrate (photomask blank) having a specific substrate surface shape (substrate surface shape data B), what is the coordinate accuracy of the transfer pattern when set in the exposure device? The results obtained by simulation are shown below (resulting in that the coordinate accuracy of the pattern formed on the transfer-receiving body will be improved).

  First, a specific test pattern was drawn on the photomask blank using a drawing device. The test photomask blank used here had a light-shielding film and a positive photoresist film formed on the main surface of a quartz substrate having a size of 850 mm × 1200 mm.

  The pattern design data used here was a test pattern including a cross pattern arranged on almost the entire main surface at 75 mm intervals in the X and Y directions. Then, this photoresist was developed and the light-shielding film was wet-etched to obtain a test photomask having a light-shielding film pattern. FIG. 17 (a) shows the result of setting this on the coordinate inspection device and measuring the coordinates.

  Incidentally, here, the stage flatness of the drawing apparatus, and the coordinate deviation factor caused by the stage flatness of the coordinate inspection apparatus, by measuring the stage flatness of both devices in advance, from the data of FIG. 17 (a) It has been removed.

  Next, a simulation was performed on the coordinate shift in the state where the test photomask was set in the exposure apparatus (equal magnification projection exposure method). Here, using the exposure apparatus of the above method <1>, using the shape information of the mask holding member, the vacuum pressure condition, and the substrate information, the coordinate deviation occurring in the test pattern is calculated using the finite element method. The data (comparative example) of FIG. 17 (b) was obtained.

  On the other hand, when drawing the same test pattern on the photomask blank, the coordinate system of the drawing machine was corrected to draw the pattern design data. The correction of the coordinate system was performed by obtaining the coordinate deviation amount data for drawing in the above steps II to V. The test photomask obtained as a result is set in a coordinate inspection apparatus, and the result of coordinate measurement is shown in FIG. 17 (c).

  Next, with respect to the coordinate shift in the state in which the test photomask obtained as a result was set in the exposure apparatus, simulation was performed in the same manner as above. The result of the simulation is shown in FIG. 17 (d) (Example).

  It can be seen from FIG. 17D that a transfer image closer to the pattern design data can be obtained on the transfer target compared to FIG. 17B. In the photomask manufactured by the method of the present invention, the coordinate accuracy is high and the coordinate error value can be suppressed to less than 0.15 μm. That is, it is possible to obtain an accuracy in which error components other than the coordinate shift caused by the capability of the drawing device are almost removed.

10 stage 11 drawing means 12 measuring means 13 photomask blank 14 thin film 15 drawing data creating means 20 surface 21 reference surface

Claims (10)

A photomask blank in which a thin film and a photoresist film are formed on the main surface of a substrate is prepared, and including a drawing device drawing a predetermined transfer pattern, in a manufacturing method of a display device manufacturing photomask,
A step of preparing pattern design data A based on the design of the predetermined transfer pattern,
A step of preparing thickness distribution data T showing the thickness distribution of the substrate,
The step of preparing transfer surface shape data C, which shows the shape of the main surface when the photomask is held in an exposure device,
A step of obtaining drawing difference data F by obtaining a difference between the thickness distribution data T and the transfer surface shape data C;
A step of calculating the coordinate deviation amount at a plurality of points on the main surface corresponding to the drawing difference data F, and obtaining the drawing coordinate deviation amount data G;
A method of manufacturing a photomask for manufacturing a display device, comprising: a drawing step of drawing on the photomask blank using the drawing coordinate deviation amount data G and the pattern design data A. The transfer surface shape data C is obtained by reflecting the displacement generated in the surface shape when the photomask is held by the exposure device, with respect to the substrate surface shape data B indicating the surface shape of the main surface. The method for manufacturing a photomask for manufacturing a display device according to claim 1, wherein The thickness distribution data T 2 and the substrate surface shape data B are
In a state where the self-deflection does not substantially affect the shape of the substrate, a plurality of measurement points are set at corresponding positions on the main surface and on the back surface opposite to the main surface ,
Obtained by measuring the distance from the reference plane at the measurement point,
The method of manufacturing a photomask for manufacturing a display device according to claim 2 . The transfer surface shape data C is obtained by holding the photomask in the exposure device, and applying a force to the back surface of the photomask to reduce deflection against the weight of the photomask. The method for manufacturing a photomask for manufacturing a display device according to claim 1, which shows a surface shape. A drawing device used for drawing a transfer pattern on a photomask blank for manufacturing a display device in which a thin film and a photoresist film are formed on a main surface of a substrate,
Pattern design data A of the transfer pattern,
Thickness distribution data T indicating the thickness distribution of the substrate, and input means for inputting transfer surface shape data C indicating the main surface shape of the substrate in a state where the substrate is held in an exposure device,
Calculation means for calculating the difference between the thickness distribution data T and the transfer surface shape data C, and calculating the drawing coordinate deviation amount data G at a plurality of points on the main surface,
A drawing apparatus comprising: a drawing unit that draws on the photomask blank using the drawing coordinate shift amount data G and the pattern design data A. In a photomask inspection method for inspecting a display device manufacturing photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate using an inspection device,
The photomask, in a state of being placed on the stage of the inspection device, performing coordinate measurement of a pattern formed on the main surface, and obtaining pattern coordinate data L,
A step of preparing thickness distribution data T showing the thickness distribution of the substrate,
The step of obtaining the transfer surface shape data C showing the shape of the main surface when the photomask is held in an exposure device,
Said thickness distribution data T, by obtaining a difference between the transfer surface shape data C, a step of obtaining a test difference data J,
Calculating a coordinate deviation amount at a plurality of points on the main surface corresponding to the inspection difference data J, and obtaining inspection coordinate deviation amount data K;
A method of inspecting a photomask, comprising an inspection step of inspecting the transfer pattern using the inspection coordinate shift amount data K and the pattern coordinate data L. The transfer surface shape data C is obtained by reflecting the displacement generated in the surface shape when the photomask is held by the exposure device, with respect to the substrate surface shape data B indicating the surface shape of the main surface. 7. The method for inspecting a photomask according to claim 6, wherein. The thickness distribution data T 2 and the substrate surface shape data B are
In a state where the self-deflection does not substantially affect the shape of the substrate, a plurality of measurement points are set at corresponding positions on the main surface and on the back surface opposite to the main surface ,
Obtained by measuring the distance from the reference plane at the measurement point,
The photomask inspection method according to claim 7. The transfer surface shape data C is obtained by holding the photomask in the exposure device and applying a force to the back surface of the photomask against the self-weight of the photomask to reduce deflection. The photomask inspection method according to claim 6, which shows the shape of the surface. A photomask inspection device for inspecting a display device manufacturing photomask having a transfer pattern formed by patterning a thin film on a main surface of a substrate, comprising:
Performing coordinate measurement of the pattern formed on the main surface to obtain pattern coordinate data L, coordinate measuring means,
Pattern design data A of the transfer pattern,
Thickness distribution data T showing the thickness distribution of the substrate,
Transfer surface shape data C indicating the main surface shape of the substrate in a state where the substrate is held in the exposure device
Input means for inputting,
Obtaining a difference between the thickness distribution data T and the transfer surface shape data C, and computing the inspection coordinate deviation amount data K at a plurality of points on the main surface, computing means,
A photomask inspection device having an inspection means for inspecting the transfer pattern of the photomask by using the inspection coordinate shift amount data K and the pattern design data A.