JP3462989B2 - Photomask and method of making the same - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a photomask and a method for producing the same, and more particularly to a photomask having a mask pattern having a small pattern sparse density dependency and a method for producing the same.

[0002]

2. Description of the Related Art In the process of manufacturing a semiconductor device, when a pattern is formed on a wafer, for example, a gate electrode pattern,
When forming a wiring pattern or the like, exposure is usually performed on a wafer through a photomask (hereinafter simply referred to as a mask), and the gate electrode mask pattern, the wiring mask pattern, etc. formed on the mask are exposed on the wafer photomask. Transferred onto the resist film. Although there are various exposure methods, in general,
A photoresist film having a film thickness of 0.5 μm to 3.0 μm is applied on a wafer, and a mask is attached to a reduction projection type exposure apparatus called a stepper, which is 1/4 times to 1 / the mask pattern provided on the mask. A fivefold pattern is transferred onto the photoresist film. Therefore, a mask pattern that is four to five times as large as the transfer pattern transferred onto the photoresist film is usually formed on the mask.

By the way, as the patterns, there are patterns such as wiring patterns in which a plurality of lines are arranged in parallel at different line pitches and the sparse density of the patterns is different. In addition, there are patterns having different sparse densities including a dense pattern and an isolated pattern. When mask patterns with different sparse densities are transferred onto a wafer by using a mask, the transferred patterns are the finished dimensions of the transfer pattern formed on the photoresist film due to the proximity effect of the patterns that are close to each other. However, it tends to vary depending on the sparse density of the mask pattern. Further, in the repetitive pattern, the pattern that should originally be transferred with the same dimension is different between the repetitive part of the pattern and the end part of the repetitive part, and further between the repetitive part and the isolated line due to the different pattern sparse density. Line width dimensions are often different.

Now, with reference to FIGS. 8 and 9, the difference in the dimensional accuracy of the pattern due to the sparse density of the pattern and its correction method will be described in more detail. FIG. 8 is a graph showing the relationship between the pattern pitch (pattern sparse density) and the pattern size that requires strict finishing size accuracy in order to realize good device characteristics. In FIG. 8, the line pattern is taken as the pattern, the line width of the line pattern is taken as the pattern dimension, and a mask pattern of a large number of line patterns having a constant line width and different line pitches is transferred to the photoresist film. A graph showing the relationship between the line width of the obtained transfer pattern and the line pitch of the transfer pattern is shown. FIG. 8 shows the line pitch on the horizontal axis and the line line width of the transfer pattern at that line pitch on the vertical axis, and the pitch P ₀ is that the line pitch dimension is twice the line line width. Means that the line pitch (μm) on the horizontal axis represents the dimensional increment of the line pitch added to the line pitch. The line line width of the obtained transfer pattern varies depending on the line pitch size, as shown in FIG. 8, and the line line width is smaller than the desired line line width size. In this case, it is difficult to form a line pattern having a desired line width on the wafer.

Therefore, conventionally, based on the fluctuation of the line width shown in FIG. 8, as shown in FIG. 9, the fluctuation of the line width for each different pitch, that is, the decrease of the line width is compensated. As a mask pattern with a bias added in advance to the design line width of the line-shaped pattern is formed, and exposure is performed using this. The line width added as compensation is a multiple of the grid size (interval between grid points that can be used as a drawing position) of the mask-making electron beam drawing apparatus.

[0006]

However, with the miniaturization of the pattern corresponding to the miniaturization and high integration of the semiconductor device, in the conventional exposure using the bias-added mask pattern, the pattern dimension is as desired. It is difficult to form a transfer pattern. This is because it is difficult to create a mask pattern to which a bias with a delicate dimension is added, because the degree of freedom in adding the bias is restricted by the grid size of the electron beam drawing apparatus used to create the mask. For example, when a quadruple reticle is created by an electron beam drawing apparatus having a 20 nm grid size, a bias can be added only on the reticle in steps of 5 nm (transfer pattern size conversion). Furthermore, since the inclination of the mask linearity (the ratio of the resist finished dimension variation to the mask dimension variation) is about 2 to 3 in a fine pattern, the correction of the resist pattern dimension is about 10 n.
It can only be done in m steps. With the miniaturization of patterns, it is required that the dimensional error of the pattern dimensions be ± 5% or less. However, when the line width is 0.18 μm,
According to the conventional method, the dimensional error of the line width is 10% or more of the line width.

As described above, in the conventional correction of the mask pattern, the correction unit is limited by the grid size of the electron beam drawing apparatus, and it is not possible to cope with the miniaturization of the pattern. Therefore, it is desired to realize a technique capable of correcting the mask pattern in a finer unit than the conventional correction unit. Therefore, an object of the present invention is to provide a photomask capable of correcting a mask pattern of a photomask in minute units and transferring a pattern having a desired pattern size.

[0008]

In order to develop a mask having a mask pattern capable of forming a transfer pattern having a small dimensional error, the present inventor made various attempts to develop a target line width dimension of the transfer pattern. When forming a line-shaped pattern with S as a mask pattern,
As shown in (a), a mask pattern having minute protrusion patterns A having a protrusion height G and a protrusion width G provided on the side portions at a constant pitch P was formed and exposed on the photoresist film. Here, the protrusion height G and the protrusion width W are grid size dimensions of the mask drawing apparatus. As shown in FIG. 10B, the transfer pattern formed on the photoresist film had a line width of the target line width dimension S + d (where 0 ≦ d ≦ 2G).

Further, the projection height is 5 nm (converted pattern size conversion, 20 nm as a reticle on the mask pattern is 20 nm) and the projection width is 5 nm (transfer pattern size conversion, on both sides of the mask pattern of an isolated line having a target line width of 0.18 μm). Protrusions of 20 nm) are provided at a constant pitch on the mask pattern, and the predetermined pitch of the protrusion pattern is 10 nm to 20 nm.
When mask patterns having various values of 0 nm (converted pattern size conversion, a mask pattern has a size of 4 times as a reticle) were formed, and light intensity distribution was simulated, the results shown in FIG. 11 were obtained. The pitch shown on the abscissa of FIG. 11 is equivalent to the transfer pattern size, and is four times the pitch shown on FIG. 11 as a reticle on a mask pattern, and the pattern size shown on the ordinate of FIG. In terms of transfer pattern size conversion, the pattern size is four times as large as the pattern size shown in FIG. 11 as a reticle on a mask pattern.

Further, FIG. 12 is a graph showing the light intensity distribution at each surface position of the cross section of the transfer pattern obtained by transferring it onto the photoresist film using the mask pattern having the above-mentioned protrusion pattern. 6 is a graph showing the results of simulation calculation with various changes from 10 nm to 200 nm (converted to transfer pattern size) using the pitch of the protrusion pattern as a parameter. The horizontal cross section showing the light intensity distribution of the transfer pattern in FIG. 12 is a cross section corresponding to the cross section along the line I-I in FIG. 10. In FIG. 12, the abscissa axis represents the position of each surface of the transfer pattern obtained by transfer, and the longitudinal center line of the transfer pattern is a reference line in terms of distance in both line width directions. The light intensity reaching each surface position of the transfer pattern is shown by the specific light intensity with the light intensity to be 1.0 being set. FIG. 13 is a partially enlarged view of FIG. Further, when the same simulation calculation was performed for the cross section of the transfer pattern corresponding to the cross section along the line II-II in FIG. 10, the same result as the graphs shown in FIGS. 12 and 13 was obtained.

It means that the same light intensity distribution result is obtained in both the cross section of the transfer pattern corresponding to the cross section of line I-I and the cross section of the transfer pattern corresponding to the cross section of line II-II in FIG. It is shown that, when exposed by using the exposure device, the protrusion pattern below the resolution limit of light is not directly transferred onto the photoresist film.

From the above, irrespective of where the cross section of the mask pattern is taken, for example, in the cross section along the line I-I and the cross section along the line II-II in FIG. There is almost no difference in intensity distribution, and the pattern dimension of the transfer pattern can be corrected at the nm level by changing the setting of the pitch of the protrusion pattern, as shown in FIG. That is, the actual size of the pattern size of the isolated line transferred onto the wafer is measured to obtain the same relationship as that shown in FIG. Next, the difference between the actual pattern dimension and the target pattern dimension is calculated from the obtained relationship. Next, the required pitch dimension of the protrusions of 5 nm × 5 nm (converted to the transfer pattern dimension) capable of obtaining the pattern dimension in which the dimension difference of the pattern dimension is compensated is read from FIG. Then, by forming a mask pattern of an isolated line provided with a protrusion pattern at the read pitch dimension, the isolated line pattern of the target pattern dimension can be transferred onto the wafer.

In order to achieve the above object, based on the above findings, the photomask according to the present invention has a mask pattern similar to the transfer pattern to be transferred on the wafer on the mask surface, and reduction projection exposure is performed. In a photomask for reducing and projecting a mask pattern onto a wafer by an apparatus to form a transfer pattern, at least a part of a pattern boundary line of the mask pattern is a grid size of a pattern drawing apparatus or more, and a reduction projection type exposure apparatus A protrusion pattern having a protrusion height and a protrusion width of dimensions less than the resolution limit of
The feature is that they are provided at a predetermined pitch.

In the present invention, the predetermined pitch of the protrusions is not limited as long as it is at least twice the grid size of the pattern drawing apparatus, but is practically a multiple of the grid size. The projection height and the projection width are arbitrary as long as they are equal to or larger than the grid size of the pattern drawing apparatus and smaller than the resolution limit of the reduction projection exposure apparatus, but they are multiples of the grid size of the pattern drawing apparatus. The pattern boundary line is a boundary line that divides the pattern from a region other than the pattern, and for example, in the case of a line-shaped wiring pattern, both boundary lines extend at intervals of the wiring width. In the case of a wiring pattern, for example, a part of the pattern boundary line means one of the boundary lines extending at intervals of the wiring width, or a part of the one boundary line.

In a preferred embodiment of the present invention, the protrusion pattern is provided along the pattern boundary lines of the mask pattern which face each other. Further, the protrusion pattern is provided on the first pattern boundary line facing each other of the mask pattern and the second pattern boundary line facing each other in the direction intersecting with the first pattern boundary line. Further, the predetermined pitch of the protrusion patterns provided on the first boundary line and the predetermined pitch of the protrusion patterns provided on the second boundary line may be different from each other. Preferably, in the present invention, the predetermined pitch is set so that the pattern size of the transfer pattern becomes the target pattern size.

In order to produce a photomask having a protrusion pattern according to the present invention, a first test mask pattern having mask patterns similar to the target transfer pattern at various different pattern sparse densities is used as a wafer photomask. Based on the first step of obtaining the relation between the pattern size and the pattern sparse density of the first resist pattern transferred onto the resist film and the target pattern size and the pattern sparse density of the target transfer pattern, According to the relationship between the pattern size and the pattern sparse density obtained in step 1,
The second step of obtaining a required correction dimension of the pattern dimension of the mask pattern similar to the target transfer pattern, and at least a part of the pattern boundary line of the mask pattern similar to the target transfer pattern, which is equal to or larger than the grid size of the pattern drawing apparatus. And a plurality of second test patterns in which protrusion patterns having protrusion heights and protrusion widths that are smaller than the resolution limit of the reduction projection type exposure apparatus are provided at different pitches from each other.
A third step of forming a test photomask having a mask pattern, and a second step obtained by transferring a plurality of second test mask patterns onto the photomask film using the test photomask. In the second step from the fourth step of obtaining the relationship between the pattern dimension of the resist pattern and the predetermined pitch of the protrusion pattern, and from the relationship between the pattern dimension of the fourth step and the predetermined pitch of the protrusion pattern. A fifth step of obtaining a predetermined pitch of the projection patterns that realizes the required correction dimension of the pattern dimensions, and a sixth step of creating a photomask having a mask pattern having the predetermined pitch of the projection patterns obtained in the fifth step. And the steps of.

In the photomask according to the present invention, instead of the projection pattern, a recess pattern having a recess depth and a recess width which is equal to or larger than the grid size of the pattern drawing apparatus and less than the resolution limit of the reduction projection exposure apparatus is used. You may make it provide at a predetermined pitch. Further, in order to form a photomask having a concave pattern according to the present invention, a first test mask pattern having various mask sparse patterns similar to the target transfer pattern at different pattern sparse densities is used as a photoresist film on a wafer. Transferred on, the first obtained by transfer
Of the pattern dimension of the resist pattern and the pattern sparse density, and the pattern dimension and the pattern sparse density obtained in the first step based on the target pattern dimension and the pattern sparse density of the target transfer pattern. The second step of obtaining the required correction dimension of the pattern dimension of the mask pattern similar to the target transfer pattern according to the relationship, and the grid size of the pattern drawing device on at least a part of the pattern boundary line of the mask pattern similar to the target transfer pattern. As described above, a plurality of second recesses having recess heights and recess widths having dimensions less than the resolution limit of the reduction projection type exposure apparatus are provided at various mutually different pitches.
And a third step of forming a test photomask having a test mask pattern of 1), and transferring a plurality of second test mask patterns onto the photomask film using the test photomask, In the second step, the fourth step of obtaining the relationship between the pattern dimension of the second resist pattern and the predetermined pitch of the recess pattern and the second step from the relationship of the pattern dimension of the fourth step and the predetermined pitch of the recess pattern The fifth step of obtaining a predetermined pitch of the recess pattern that realizes the required correction dimension of the pattern dimension and the sixth step of producing a photomask having a mask pattern having the predetermined pitch of the recess pattern obtained in the fifth step. And a step.

In the method for producing a photomask according to the present invention,
The pattern sparse density means sparse / dense spacing between patterns, and in the case of a line-shaped pattern such as a wiring pattern, it means a line pitch of the line-shaped pattern.

In place of the third step and the fourth step, a photomask characterized in that the relationship between the pattern size of the second resist pattern and the predetermined pitch of the protrusion pattern or the recess pattern is obtained by simulation. Method.

[0020]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described specifically and in detail with reference to the accompanying drawings by way of example embodiments. Embodiment 1 This embodiment is an example of an embodiment of a photomask according to the present invention, and FIG. 1 is a plan view showing the configuration of the photomask of this embodiment. The photomask of the present embodiment is a 4 × photomask used when a wiring pattern is transferred onto a wafer by a reduction projection type exposure apparatus.
A large number of mask patterns 10 shown in FIG. 1 are provided in series and in parallel. As shown in FIG. 1, the mask pattern 10 includes a mask pattern body 12 that is similar to the transfer pattern, and protrusions that are provided on all lines of one of the longitudinal pattern boundary lines 14A and B of the mask pattern body 12 that face each other. And a partial pattern 16. Projection pattern 16
Are provided at a predetermined pitch P with a projection height H and a projection width W that are equal to or larger than the grid size of a pattern drawing apparatus, for example, an electron beam drawing apparatus, and less than the resolution limit of a reduction projection exposure apparatus. . In this embodiment, the photomask is four times larger, and the grid size of the electron beam drawing apparatus is 20 nm.
The protrusion height H of the protrusion pattern 16 is 20 nm,
The protrusion width W is 20 nm. The pitch P is a multiple of the protrusion width W and is, for example, 80 nm. Note that the mask magnification and the grid size of the electron beam drawing apparatus are the same in the following embodiments.

Embodiment 2 This embodiment is another example of the embodiment of the photomask according to the present invention, and FIG. 2 is a plan view showing the configuration of the photomask of this embodiment. The photomask of the present embodiment is a photomask used when a wiring pattern is transferred onto a wafer by a reduction projection type exposure apparatus.
A large number of mask patterns 20 shown in are provided in series and in parallel. As shown in FIG. 2, the mask pattern 20 is provided at a predetermined pitch P on both the mask pattern body 12 that is similar to the transfer pattern and the longitudinal pattern boundary lines 14A and 14B of the mask pattern body 12 that face each other. And the projected portion pattern 22 is formed. Projection pattern 22
Has a projection height H and a projection width W that are equal to or larger than the grid size of a pattern drawing apparatus, for example, an electron beam drawing apparatus, and less than the resolution limit of a reduction projection exposure apparatus. In the present embodiment, the protrusion height H of the protrusion pattern 22 is 20 nm and the protrusion width W is 20 nm. The pitch P is a multiple of the protrusion width W and is, for example, 80 nm.

Modification of Second Embodiment This modification is a modification of the second embodiment, and FIG. 3 is a plan view showing the configuration of the photomask of the modification. In the mask pattern 30 of the photomask of this modified example, as shown in FIG. 3, the protrusion patterns 22 provided on all the lines of the longitudinal pattern boundary lines 14A and 14B are aligned in the longitudinal direction of the mask pattern body 12. It is arranged in a staggered pattern.

Embodiment 3 This embodiment is another example of the embodiment of the photomask according to the present invention, and FIG. 4 is a plan view showing the structure of the photomask of this embodiment. The photomask of this embodiment is a photomask used when transferring a contact hole pattern onto a wafer by a reduction projection type exposure apparatus, and has a large number of mask patterns 40 shown in FIG. 4 in series and in parallel. . As shown in FIG. 4, the mask pattern 40 includes a mask pattern body 42 that is similar to a transfer pattern, first pattern boundary lines 44A and 44B that face each other in the mask pattern body 42, and a first pattern boundary line 44A. , B on the second pattern boundary lines 46A, B facing each other in a direction intersecting with B, B. The projection pattern 48 has a projection height H and a projection width W that are equal to or larger than the grid size of a pattern drawing apparatus, for example, an electron beam drawing apparatus, and are less than the resolution limit of the reduction projection type exposure apparatus. Then, the protrusion height H of the protrusion pattern 48 is 20 nm, and the protrusion width W is 20 nm. The pitch P is a multiple of the protrusion width W and is, for example, 80 nm.

Modification of Third Embodiment The present modification is a modification of the second embodiment, and FIG. 5 is a plan view showing the configuration of the photomask of the modification. In the mask pattern 50 of the photomask of this modified example, as shown in FIG. 5, the pitch P ₁ of the protrusion pattern 52 provided on the first pattern boundary lines 44A and B facing each other of the mask pattern body 42 , The first pattern boundary line 44
The pitch P ₂ of the protrusion patterns 48 provided on the second pattern boundary lines 46A and 46B facing each other in the direction intersecting with A and B is different from each other. The pitch P ₁ is three times the protrusion width W of the protrusion 48, and the pitch P ₂ is twice the protrusion width W of the protrusion 48.

Embodiment 4 This embodiment is another example of the embodiment of the photomask according to the present invention, and FIG. 6 is a plan view showing the configuration of the photomask of this embodiment. The photomask of this embodiment is a photomask used when a wiring pattern is transferred onto a wafer by a reduction projection type exposure apparatus.
A large number of mask patterns 60 shown in are provided in series and in parallel. As shown in FIG. 6, the mask pattern 60 has a concave pattern 66 on all lines of a mask pattern main body 62 similar to the transfer pattern and longitudinal pattern boundary lines 64A and B facing each other of the mask pattern main body 62. It is provided at a predetermined pitch P. The recess pattern 66 has a recess depth H and a recess width W that are equal to or larger than the grid size of a pattern drawing apparatus, for example, an electron beam drawing apparatus, and less than the resolution limit of a reduction projection exposure apparatus. The recess pattern pattern 66 has a recess depth H of 20 nm and a recess width W of 20 n.
m. The pitch P is a multiple of the recess width W and is, for example, 80 nm.

A sample photomask having the same structure as the photomasks of Embodiments 1 to 4 and the modified example was prototyped and transferred onto the photoresist film of the wafer using a reduction projection type exposure apparatus to form a resist pattern. When the dimensions of the formed resist pattern were measured, the pattern sparse density dependency was small and the pattern dimension was almost the desired dimension.

Embodiment 5 This embodiment is an example of the embodiment of the photomask making method according to the present invention, and FIG. 7 shows the flow of steps of the photomask making method of this embodiment. It is a flowchart. The present embodiment example is a method of forming a photomask according to the second embodiment. First, in the first step S ₁ , a first test including mask patterns similar to the line pattern to be transferred at various different line pitches.
The mask pattern is transferred onto the photoresist film on the wafer, and the relationship between the pattern size and the line pitch of the first resist pattern (line-shaped pattern) obtained by transfer is obtained. In the first step, for example, the relationship shown in FIG. 8 is obtained.

Then, in a second step S ₂ , according to the relationship between the line width and the line pitch obtained in the first step,
Based on the target line width and the line pitch of the target line-shaped pattern, the required correction dimension of the line width of the mask pattern similar to the target line-shaped pattern is obtained. For example, taking FIG. 8 as an example, when the line pitch of the target line-shaped pattern is P ₁ , the required correction dimension of the line width of the mask pattern is 4 × W ₁
Is.

In the third step S ₃ , on the pattern boundary lines 14A and 14B of the mask pattern main body 12 of FIG. 2, dimensions which are equal to or larger than the grid size of the pattern drawing apparatus and smaller than the resolution limit of the reduction projection type exposure apparatus. A test photomask having a plurality of second test mask patterns in which the protrusion patterns 22 having the protrusion height and the protrusion width are provided at various mutually different predetermined pitches is prepared. The projection pattern has a projection height H and a projection width W that are equal to or larger than the grid size of a pattern drawing apparatus, for example, an electron beam drawing apparatus, and less than the resolution limit of a reduction projection exposure apparatus. In this embodiment, the protrusion height H of the protrusion pattern is 20 nm and the protrusion width W is 20 nm. The pitch P is a multiple of the protrusion width W and is, for example, 80 nm.

In the fourth step S ₄ , a test photomask having a plurality of second test mask patterns respectively is used for transfer onto the photomask film, and the line width of the line-shaped pattern obtained by the transfer is transferred. The relationship between the dimension and the predetermined pitch of the protrusion pattern is obtained. For example, the relationship as shown in FIG. 11 is obtained.

In the fifth step S ₅ , the line width of the transferred linear pattern is set to the target line width + the required correction dimension of the line width of the mask pattern obtained in the second step.
The pitch of the protrusion pattern is obtained from the relationship obtained in the fourth step.

In the sixth step S ₆ , a photomask having the same structure as the mask pattern 20 shown in FIG. 2 and having the mask pattern having the pitch of the protrusion pattern obtained in the fifth step is prepared.

Further, instead of the third step S ₃ and the fourth step S ₄ , the relationship between the dimension of the line width of the line pattern corresponding to FIG. 11 and the predetermined pitch of the protrusion pattern is obtained by simulation. Is also good.

[0034]

According to the present invention, at least a part of the pattern boundary line of the mask pattern similar to the transfer pattern is larger than the grid size of the pattern drawing device,
By providing a projection pattern having a projection height and a projection width of dimensions less than the resolution limit of the reduction projection type exposure apparatus at a predetermined pitch, the mask pattern of the photomask is corrected in a minute unit which is much smaller than the conventional one, and a desired pattern is obtained. A pattern having a pattern size can be transferred onto the photoresist film. The method of the present invention implements a preferred method of making the photomask of the present invention.

[Brief description of drawings]

FIG. 1 is a plan view showing a configuration of a photomask according to a first exemplary embodiment.

FIG. 2 is a plan view showing a configuration of a photomask according to a second exemplary embodiment.

FIG. 3 is a plan view showing a configuration of a photomask of a modified example of the second embodiment.

FIG. 4 is a plan view showing the configuration of a photomask according to the third embodiment.

FIG. 5 is a plan view showing a configuration of a photomask of a modified example of the third embodiment.

FIG. 6 is a plan view showing the configuration of a photomask according to the fourth embodiment.

FIG. 7 is a flowchart showing a flow of a method for producing a photomask.

FIG. 8 is a graph showing the relationship between the measured value of the pattern dimension (line width) of the resist pattern (wiring pattern) and the pitch of the wiring pattern of the mask pattern.

FIG. 9 is a graph showing a relationship between a bias addition wiring pattern and a pitch.

10A is a plan view of a mask pattern having a protrusion pattern, and FIG. 10B is a plan view of a resist pattern obtained by transferring the mask pattern of FIG. 10A.

FIG. 11 is a graph showing the relationship between the pitch of the protrusion pattern and the pattern dimension of the resist pattern.

FIG. 12 is a graph showing the relationship between the surface position of the mask pattern cross section and the specific light intensity at that position.

13 is a partially enlarged view of FIG.

[Explanation of symbols]

10 Mask Pattern of Photomask of Embodiment 1 12 Mask Pattern Body 14 Longitudinal Pattern Boundary 16 Projection Pattern 20 Mask Pattern of Photomask of Embodiment 2 22 Projection Pattern 30 Photo of Modification of Embodiment 2 Mask pattern 40 of mask Mask pattern 42 of photomask of Embodiment 3 Mask pattern body 44 First pattern boundary line 46 Second pattern boundary line 48 Projection pattern 50 Mask of photomask of modified example of Embodiment 3 Pattern 60 Mask pattern 62 of the photomask of Embodiment 4 Mask pattern body 64 Longitudinal pattern boundary line 66 Recessed pattern

Claims (4)

(57) [Claims] 1. A photomask which has a mask pattern similar to a transfer pattern to be transferred onto a wafer on a mask surface, and reduces and projects the mask pattern onto the wafer by a reduction projection type exposure apparatus to form a transfer pattern, Except for the corners of the mask pattern, at least a part of the pattern boundary line of the mask pattern has a projection height and a projection width that are equal to or larger than the grid size of the pattern drawing apparatus and less than the resolution limit of the reduction projection exposure apparatus. A photomask, characterized in that the projection pattern having the following is provided at a predetermined pitch defined as a multiple of the projection width . 2. The protrusion patterns are provided at the same predetermined pitch or different predetermined pitches, except for the corners of the mask pattern, along both pattern boundary lines facing each other of the mask pattern. The photomask according to claim 1. 3. At least one of the first pattern boundary lines facing each other of the mask pattern and at least one of the second pattern boundary lines facing each other in a direction intersecting with the first pattern boundary line, The photomask according to claim 1, wherein the protrusion patterns are provided at a predetermined pitch except for the corners of the mask pattern. 4. The predetermined pitch of the projection patterns provided on the first boundary line and the predetermined pitch of the projection patterns provided on the second boundary line are different from each other. The described photo mask.