TWI545391B - Mask and method of forming pattern by using the same - Google Patents

Description

Photomask and method of forming a pattern

The present invention relates to a reticle and a method of forming a pattern, and more particularly to a reticle having an auxiliary pattern and a method of forming a pattern using the reticle.

As electronic products and their peripheral products are developing in a light, thin and short direction, in the semiconductor manufacturing process, component shrinkage and accumulation are inevitable trends, and they are also important topics for active development. Among them, lithography determines component performance. The key technology.

The current semiconductor process first forms a design pattern of integrated circuits on a reticle, and then transfers the pattern on the reticle to the photoresist layer on the semiconductor wafer by a ratio of exposure and development steps. And further, in conjunction with the associated etching process, the components are gradually formed on the semiconductor wafer. As the integration of the integrated circuit increases, the component size shrinks and the distance between the component and the component decreases. However, due to factors such as optical proximity effect (OPE), the distance of the above components has reached its limit in the exposure process. For example, in order to obtain a small-sized component, the pitch of the light-transmitting region of the photomask will be reduced in accordance with the size of the device, but if the interval between the light-transmitting regions is reduced to a specific range (the exposure wavelength is 1/2) Or when the light passing through the reticle may be diffracted, interfered, etc., thereby affecting the resolution of the transferred pattern, causing deviations in the pattern on the photoresist, such as right-angled round-angled Corner rounded), line end shortened, and line width increase/decrease are all defects of the photoresist pattern caused by the common optical proximity effect. In addition, when there are different intervals between the light-transmitting regions of the reticle and different pattern distribution densities, light passing through the light-transmissive regions with smaller intervals may be affected by the light-transmitting regions having larger intervals, so that after the transfer The pattern is distorted or produces a micro-loading effect.

In order to solve the above problems, the prior art forms a dummy pattern on adjacent spaces between light-transmitting regions having different intervals, so that light caused by an optical proximity effect when the pattern is transferred onto the photoresist layer Resistive pattern defects are produced on the dummy pattern to ensure that the photoresist pattern actually used can be formed intact. Another method employed by the prior art is to form a plurality of scattering bars on adjacent spaces between the light-transmissive regions having different intervals, whereby the arrangement of the dispersion strips causes the pattern to be transferred to the photoresist On the layer, the photoresist pattern in the light-transmissive region with a small interval is not affected by the optical proximity effect. However, the dummy pattern is formed on the semiconductor wafer, causing the available area of the semiconductor wafer to decrease, and the arrangement of the dispersion strips also consumes the available area of the mask, increasing the layout budget of the mask. Therefore, when the light-transmitting regions of the reticle have different intervals, how to maintain the integrity of the photoresist pattern in the light-transmitting region with a small interval is a problem that the related art desires to improve.

It is an object of the present invention to provide a photomask having an auxiliary pattern and a method of forming a pattern using the photomask to improve the correctness of the formed pattern.

A preferred embodiment of the present invention provides a photomask including a substrate, at least a first strip pattern, at least a second strip pattern, and an auxiliary pattern. A width of the second strip pattern is substantially larger than a width of the first strip pattern, and the auxiliary pattern is disposed in the second strip pattern of the adjacent first strip pattern, wherein the auxiliary pattern does not overlap the second strip One of the centerlines of the pattern.

Another preferred embodiment of the present invention provides a method of forming a pattern comprising the following steps. First, a layout pattern is provided. The layout pattern includes at least one first strip pattern and at least one second strip pattern, and a width of the second strip pattern is substantially larger than a width of the first strip pattern. Next, the second strip pattern of the adjacent first strip pattern is defined as a selected pattern, and an auxiliary pattern is formed in the selected pattern, wherein the auxiliary pattern does not overlap one of the center lines of the selected pattern. Then, the layout pattern and the auxiliary pattern are output to a mask.

The present invention provides a reticle having an auxiliary pattern of at least one opening disposed in a second strip pattern of adjacent first strip patterns and a method of forming a pattern using the reticle, wherein the width of the second strip pattern is It is substantially larger than the width of the first strip pattern. The auxiliary pattern is used to homogenize the amount of light passing through both sides of the first strip pattern in the lithography process to improve the correctness of the pattern formed by the first strip pattern adjacent to the second strip pattern on the reticle.

The present invention will be further understood by those of ordinary skill in the art to which the present invention pertains. .

The present invention provides a photomask, please refer to FIG. FIG. 1 is a schematic view showing a photomask according to a first preferred embodiment of the present invention. As shown in FIG. 1, the photomask 100 includes a substrate 12, a plurality of strip patterns 14 and an auxiliary pattern 20. The substrate 12 comprises a transparent glass substrate, a quartz substrate, a transparent plastic substrate or a substrate formed of other suitable permeable materials. The plurality of strip patterns 14 are made of a material that is opaque, such as chromium (Cr), which is disposed on the substrate 12 and may include a plurality of printable features, and the transferable patterns are Any feature pattern for forming an integrated circuit (IC), such as a doped region pattern, an element pattern, a wiring pattern, or the like, may be included. In addition, the strip patterns 14 include at least one first strip pattern 16 and at least one second strip pattern 18, wherein a width of the second strip pattern 18 is substantially larger than a width of the first strip pattern 16 And the second strip pattern 18 has a center line L. The first strip pattern 16 and the second strip pattern 18 both extend along a first direction D1 and are arranged parallel to each other along a second direction D2, wherein the first direction D1 is perpendicular to the second direction D2. In addition, the center line L of the second strip pattern 18 is parallel to the first direction D1, and the first strip pattern 16 is parallel to the center line L of the second strip pattern 18, but is not limited thereto. The auxiliary patterns 20 are disposed in the second strip patterns 18 of the adjacent first strip patterns 16A, and do not overlap the center line L of the second strip patterns 18 and are preferably parallel to the center line L of the second strip patterns 18. In the preferred embodiment, the auxiliary pattern 20 is a light-transmissive opening disposed in the second strip-shaped pattern 18 that is opaque, wherein the width of the cross-section of the auxiliary pattern 20 along the second direction D2 is less than a specific value. That is, the maximum size of the pattern that is not exposed in the reticle 100, and greater than the exposure limit of the reticle forming machine, the minimum size of the pattern formed by the reticle forming machine, and more specifically, the feature size For a semiconductor process of 20 nanometers (nm), the maximum size of the pattern that is not exposed in the mask 100 is substantially about 32 nm, and the exposure limit of the mask manufacturing machine is substantially about 13 Nano, so the width of the cross section of the auxiliary pattern 20 in the second direction D2 is substantially between 13 nm and 32 nm. In other words, the auxiliary pattern 20 is a non-printable feature, that is, when the photomask 10 is used to perform a photosensitive layer (not shown) on one of the wafers. During the shadowing process, only the first strip pattern 16 that is opaque and the second strip pattern 18 that is opaque may correspond to a first pattern (not shown) and a second pattern (developed) after development. Not shown) is formed on the material layer, and in the second pattern formed corresponding to the development of the second strip pattern 18, the opening corresponding to the auxiliary pattern 20 does not occur. In addition, a plurality of first gaps (not shown) may be defined between the first pattern and the adjacent first pattern, that is, each first gap corresponds to two adjacent first strip patterns 16 on the reticle 100. Each of the first gaps SP1 and a second gap (not shown) may be defined between the first pattern and the adjacent second pattern, that is, each second gap corresponds to the first strip on the reticle 100. Each of the second gaps SP2 between the pattern 16 and the second strip pattern 18.

It should be noted that, since the width of the first strip pattern 16 is different from the width of the second strip pattern 18, in a subsequent lithography process, if a light source having the same energy is received, for example, 248 nm (nanometer, hereinafter referred to as For nm) KrF or 193 nm deep UV illumination, the maximum light intensity value received by each first gap on the material layer will be different from the maximum light intensity value received by the second gap, ie It is said that the light intensity value received by one side of the first pattern formed on the material layer by the first strip pattern 16A will also be different from the light intensity value received by the other side of the first pattern, therefore, The phenomenon that the first pattern will be offset. Accordingly, in the present embodiment, the light-transmissive auxiliary pattern 20 is completely disposed in the second strip-shaped pattern 18 of the adjacent first strip-shaped pattern 16A that is opaque, that is, the second strip-shaped pattern. The opaque material of 18 completely surrounds the auxiliary pattern 20, and the auxiliary pattern 20 is a non-transferable pattern, which is not developed on the material layer, and is used to adjust the maximum light intensity value received by the second gap, thereby reducing The first strip pattern 16A forms a difference in light intensity values received by one side of the first pattern on the material layer and the other side to avoid deformation of the first pattern.

With continued reference to FIG. 1, in the present embodiment, the auxiliary pattern 20 includes an opening, and the opening may include at least one geometric pattern, such as at least one rectangular pattern. The auxiliary pattern 20 is preferably parallel to the first strip pattern 16 and extends toward the first direction D1, and the light provided by the light source of the subsequent exposure process preferably passes through the mask 100 in a direction perpendicular to the plane of the paper. The preferred resolution of the pattern formed by the mask on the material layer is not limited thereto. The auxiliary pattern 20 is disposed in the second strip pattern 18, and further, the auxiliary pattern 20 is adjacent to one side S of the second strip pattern 18, and the side S is adjacent to the first strip pattern 16A. The auxiliary pattern 20 can be used to adjust the light received by the second gap such that the difference between the maximum light intensity value received by the second gap and the minimum light intensity value received by the first pattern is substantially close to the maximum light received by the first gap. a difference between the intensity value and the minimum light intensity value received by the first pattern to reduce the light intensity value received by one side of the first pattern corresponding to one side 16S1 of the first strip pattern 16A and corresponding to The difference in the light intensity values received by the other side of the first pattern of the other side 16S2 of the first strip pattern 16A helps to maintain the use of the material layer during the subsequent lithography process. The integrity of the first pattern formed by the adjacent first strip patterns 16A of the two strip patterns 18.

Since the sizes that can be imaged by different line widths and different optical settings cannot be defined in the same manner or formula, the size range of the auxiliary pattern 20 also varies depending on the line width and the optical setting. In addition, the size, shape, number and arrangement of the light-transmitting auxiliary patterns 20 disposed in the second strip-shaped pattern 18 that is opaque can be adjusted according to process requirements. The auxiliary pattern of the present invention is not limited to the above embodiment, and in other embodiments, the auxiliary pattern may also include openings or a plurality of openings having other geometric patterns. Other preferred embodiments of the present invention will be described in the following, and in order to facilitate the comparison of the various embodiments and the simplification of the description, the same elements are denoted by the same symbols in the following embodiments, and mainly for each implementation. The differences between the examples are explained, and the repeated parts are not described again.

Please refer to Figure 2. 2 is a schematic view of a photomask according to a second preferred embodiment of the present invention. As shown in FIG. 2, the photomask 200 includes a substrate 12, a first stripe pattern 16A between the first stripe pattern 16B and the second stripe pattern 18, and a second stripe pattern adjacent to the first stripe pattern 16A. The pattern 18 and the auxiliary pattern 22 disposed in the second strip pattern 18 are provided. The auxiliary pattern 22 does not overlap the center line L of the second strip pattern 18 and is preferably parallel to the center line L of the second strip pattern 18, which is different from the first preferred embodiment in that the auxiliary pattern 22 includes an opening. The upper side US and the lower side LS of the second strip pattern 18 are contacted, that is, the unclosed pattern can also be used to homogenize the light intensity values received by the sides of the first pattern.

Please refer to Figure 3. FIG. 3 is a schematic view showing a photomask according to a third preferred embodiment of the present invention. As shown in FIG. 3, the photomask 300 includes a substrate 12, a plurality of first strip patterns 16, a second strip pattern 18 adjacent to the first strip pattern 16A, and an auxiliary pattern disposed in the second strip pattern 18. twenty four. The difference from the first preferred embodiment is that the auxiliary pattern 24 includes a plurality of openings P, and each of the openings P respectively includes a geometric pattern, such as a circular shape. The openings P are disposed along the first direction D1 and are parallel to the center line L of the second strip pattern 18. In the present embodiment, the auxiliary pattern 24 is composed of a plurality of identical patterns, that is, the auxiliary pattern 24 includes a plurality of identical circular openings. In other embodiments, the openings of the auxiliary pattern may each have a different geometric pattern such as a triangle, a parallelogram, a diamond or a square.

Please refer to Figure 4. 4 is a schematic view of a photomask according to a fourth preferred embodiment of the present invention. As shown in FIG. 4, the photomask 400 includes a substrate 12, a plurality of first strip patterns 16, a second strip pattern 18 between the first strip patterns 16A/16C, and a second strip pattern 18. Auxiliary pattern 26 in the middle. As described above, the second strip pattern 18 of the adjacent first strip patterns 16A/16C is liable to cause a difference in the amount of light on both sides of the first strip pattern 16A/16C adjacent thereto in the developing process. The light intensity values received by the sides of the first pattern formed by the first strip patterns 16A/16C are different, and the shapes are shifted. Therefore, the auxiliary patterns 26 are disposed in the second strip patterns 18, so that Each of the first strip patterns 16 can be completely transferred onto the material layer to form a first pattern. In the present embodiment, the auxiliary pattern 26 includes a plurality of openings P', and each of the openings P' includes a geometric pattern such as a rectangle, and the openings P' do not overlap the center line L of the second strip pattern 18. The difference from the third preferred embodiment is that the auxiliary patterns 26 can respectively define a plurality of sub-auxiliary patterns 26', wherein the sub-auxiliary patterns 26' are respectively composed of an opening P' and are arranged at an equal interval in the second direction D2. Further, each of the sub-auxiliary patterns 26' is preferably parallel to the center line L of the second strip-like pattern 18. The auxiliary pattern 26 can adjust the light received by the second gap between the developed first pattern and the developed second pattern, so that the maximum light intensity value of the second gap and the minimum light intensity value received by the first pattern The difference is substantially equal to the difference between the maximum light intensity value received by each first gap between the first pattern and the first pattern and the minimum light intensity value received by the first pattern to maintain by being adjacent to the second The pattern of the first pattern formed by the first stripe pattern 16A/16C of the strip pattern 18 is complete. It should be noted that the distance W1/W2 between the sub-auxiliary pattern 26' and the side S1/S2 of the second strip pattern 18 and the spacing W3/W4 between the sub-auxiliary pattern 26' and the sub-auxiliary pattern 26' can be adjusted. The maximum light intensity value to achieve the second gap is substantially equal to the maximum light intensity value of the first gap.

For the same theory, please refer to Figure 5. FIG. 5 is a schematic view showing a photomask according to a fifth preferred embodiment of the present invention. As shown in FIG. 5, the photomask 500 includes a substrate 12, a plurality of first strip patterns 16, a second strip pattern 18 between the first strip patterns 16A/16C, and a second strip pattern 18. Auxiliary pattern 28 in the middle. In the embodiment, the auxiliary pattern 28 includes a plurality of openings P, and each of the openings P respectively includes a geometric pattern such as a circle, and the openings P do not overlap the center line L of the second strip pattern 18. The auxiliary patterns 28 may define a plurality of sub-auxiliary patterns 28 ′ therein, and the sub-auxiliary patterns 28 ′ are disposed at non-equal intervals in the second direction. Further, the sub-auxiliary patterns 28 ′ are preferably parallel to the center line L of the second strip-shaped patterns 18 . . The difference from the fourth preferred embodiment is that each of the sub-auxiliary patterns 28' is composed of a plurality of openings P, and the openings P in the sub-auxiliary patterns 28' are disposed along the first direction D1.

The present invention also provides a method of forming a pattern, please refer to Figures 6 to 10. 6 to 8 are schematic views showing a method of forming a pattern according to a preferred embodiment of the present invention. As shown in Fig. 6, first, a layout pattern 30 is provided, for example, the layout pattern 30 is input to a computer system (not shown). The layout pattern 30 includes a plurality of printable features, and the transferability pattern may further comprise any feature pattern for forming an integrated circuit (IC), such as a doped region pattern, an element pattern. Any wiring pattern, such as a patterned pattern, an element pattern, a wiring pattern, or the like, for forming an integrated circuit (IC). In this embodiment, the layout pattern 30 includes at least one second strip pattern 34 and a plurality of first strip patterns 32 disposed on one side of the second strip pattern 34, and the second strip pattern 34 and the plurality of first patterns The strip patterns 32 are all transferable patterns and a width of the second strip pattern 34 is substantially larger than a width of the first strip pattern 32. Each of the first stripe pattern 32 and the second strip pattern 34 extends in a first direction D1 and is disposed in parallel along a second direction D2, wherein the first direction D1 is perpendicular to the second direction D2. In addition, the center line L1 of the second strip pattern 34 is parallel to the first direction D1, and each of the first strip patterns 32 is parallel to the center line L1 of the second strip pattern 34, but is not limited thereto.

Next, as shown in FIG. 7, in the layout pattern 30, the second strip pattern 34 defining the adjacent first strip pattern 32A is a selected pattern 34', and an auxiliary pattern of the non-transferable pattern is formed. 36 is in the selection pattern 34'. The auxiliary patterns 36 are not overlapped and are preferably parallel to one of the center lines L1 of the pattern 34'. The auxiliary pattern 36 includes at least one opening, and the opening includes a geometric pattern such as a rectangle, a circle, a triangle, a parallelogram, a diamond or a square, and the like. For the configuration of the auxiliary pattern 36, please refer to the foregoing embodiment, that is, the auxiliary pattern may include a single opening (as described in the first preferred embodiment, the second preferred embodiment) or a plurality of openings (such as the third preferred embodiment). For example, and the width of the auxiliary pattern 36 in the second direction D2 is less than the minimum exposure limit of the lithography process, in other words, the auxiliary pattern 36 is a non-printable feature. In this embodiment, the auxiliary pattern 36 includes a rectangular opening. In other embodiments, the auxiliary pattern may also include a plurality of sub-auxiliary patterns 36 ′ that are parallel to each other and disposed at a non-equal interval in the selected pattern 34 ′, or toward the center line. L1 is decreasing in width, or decreasing in the distance from the center line L1 by I1/I2/I3 as shown in Fig. 8. Each sub-auxiliary pattern may comprise a single opening (as described in the fourth preferred embodiment) or a plurality of openings (as described in the fifth preferred embodiment). Finally, optical first correction (OPC) is performed on each of the first strip pattern 32 and the second strip pattern 34 as needed, as shown in FIG.

As shown in FIG. 10, the first strip pattern 32 and the second strip pattern 34 and the auxiliary pattern 36 of the layout pattern 30 are outputted to a mask 38. Further, the first gap SP1 may be defined as two adjacent firsts. Between the strip patterns 32 and the second gap SP2 may be defined between the first strip pattern 32 and the second strip pattern 34. Subsequently, a lithography process P1 is performed using the reticle 38 to form a layout pattern onto a material layer 40. The lithography process P1 can transfer the first strip pattern 32 and the second strip pattern 34 on the mask 38 onto the material layer 40 to form corresponding first patterns 42 and second patterns 44. The material layer 40 can be disposed on the semiconductor substrate 46, wherein the material layer 40 comprises a layer of photoresist material. In the reticle 38, the auxiliary pattern 36 is disposed in the selected pattern 34', that is, the auxiliary pattern 36 is disposed in the second strip pattern 34 of the adjacent first strip pattern 32A, and can be used in the lithography process P1. Adjusting the amount of light transmitted through the first gap SP1 and the second gap SP2 by one side of the first strip pattern 32A, that is, the amount of light transmitted through the second gap SP2, so that the first pattern on the material layer 40 is made The first gap SP1' between the 42A and the first pattern 42B and the maximum gap intensity value received by the second gap SP2' between the first pattern 42A and the second pattern 44 are equal, that is, the first pattern 42A is made The light intensity values received by the two sides S3/S4 are equal, reducing the effect of the microload effect to maintain the integrity of the first pattern 42A.

In summary, the present invention provides a reticle having an auxiliary pattern of at least one opening disposed in a second strip pattern of adjacent first strip patterns and a method of forming a pattern using the reticle, wherein the second The width of the pattern is substantially greater than the width of the first strip pattern. The auxiliary pattern is used to homogenize the amount of light passing through both sides of the first strip pattern in the lithography process to improve the correctness of the pattern formed by the first strip pattern adjacent to the second strip pattern.

The above are only the preferred embodiments of the present invention, and all changes and modifications made to the scope of the present invention should be within the scope of the present invention.

12. . . Substrate

14. . . Strip pattern

16,16A,16B,16C,32,32A. . . First strip pattern

16S1, 16S2. . . Side

18,34. . . Second strip pattern

20,22,24,26,28,36. . . Auxiliary pattern

26’, 28’, 36’. . . Sub-auxiliary pattern

30. . . Layout pattern

34’. . . Select pattern

38. . . Mask

40. . . Material layer

42,42A. . . First pattern

44. . . Second pattern

46. . . Semiconductor substrate

100,200,300,400,500. . . Mask

D1. . . First direction

D2. . . Second direction

I1, I2, I3. . . spacing

L, L1. . . Center line

P, P’. . . Opening

P1. . . Photolithography process

S, S1, S2, S3, S4. . . Side

SP1. . . First gap

SP2. . . Second gap

SP1’. . . First gap

SP2’. . . Second gap

US. . . Upper side

LS. . . Lower side

W1, W2, W3, W4. . . spacing

FIG. 1 is a schematic view showing a photomask according to a first preferred embodiment of the present invention.

2 is a schematic view of a photomask according to a second preferred embodiment of the present invention.

FIG. 3 is a schematic view showing a photomask according to a third preferred embodiment of the present invention.

4 is a schematic view of a photomask according to a fourth preferred embodiment of the present invention.

FIG. 5 is a schematic view showing a photomask according to a fifth preferred embodiment of the present invention.

6 to 10 are schematic views showing a method of forming a pattern according to a preferred embodiment of the present invention.

12. . . Substrate

14. . . Strip pattern

16,16A. . . First strip pattern

16S1, 16S2. . . Side

18. . . Second strip pattern

20. . . Auxiliary pattern

100. . . Mask

D1. . . First direction

D2. . . Second direction

L. . . Center line

S. . . Side

SP1. . . First gap

SP2. . . Second gap

Claims (20)

A reticle comprising: a substrate; at least one first strip pattern and at least one second strip pattern, and a width of the second strip pattern is substantially greater than a width of the first strip pattern; An auxiliary pattern is disposed in the second strip pattern adjacent to the first strip pattern, and the auxiliary pattern does not overlap a center line of the second strip pattern and is completely surrounded by the second strip pattern. The reticle of claim 1, wherein the first strip pattern is parallel to the center line of the second strip pattern. The reticle of claim 1, wherein the auxiliary pattern is parallel to the center line of the second strip pattern. The reticle of claim 1, wherein the auxiliary pattern comprises at least one opening. The reticle of claim 4, wherein the at least one opening comprises a geometric pattern. The reticle of claim 1, wherein the first strip pattern and the second strip pattern both extend in a first direction and are disposed in parallel along a second direction, the center line of the second strip pattern The first direction is parallel, and the first direction is perpendicular to the second direction. The reticle of claim 6, wherein a width of a cross section of the auxiliary pattern along the second direction is less than a specific value, such that the auxiliary pattern is not exposed through the exposure process and the development process. A maximum size of the pattern on the reticle. The reticle of claim 7, wherein the specific value is substantially 32 nanometers (nm). The reticle of claim 6, wherein the auxiliary pattern comprises a plurality of openings, the openings being disposed at non-equal intervals along the second direction. The reticle of claim 9 wherein each of the openings comprises a geometric pattern. The reticle of claim 1, wherein when the reticle is used to perform a lithography process on a material layer, only the first strip pattern and the pattern of the second strip pattern are formed on the material layer. A method of forming a pattern, comprising: providing a layout pattern to a computer system, the layout pattern comprising at least a first strip pattern and at least a second strip pattern, and a width of the second strip pattern is substantially a width greater than the width of the first strip pattern; defining the second strip pattern adjacent to the first strip pattern as a selected pattern; forming an auxiliary pattern in the selected pattern, and the auxiliary pattern does not overlap the selection Figure One of the centerlines is completely surrounded by the second strip pattern; and the layout pattern and the auxiliary pattern are output by the computer system to a reticle. The method of forming a pattern as claimed in claim 12, further comprising performing a lithography process using the mask to form the layout pattern onto a layer of material. A method of forming a pattern as claimed in claim 12, wherein the first strip pattern is parallel to a centerline of the second strip pattern. A method of forming a pattern as claimed in claim 12, wherein the auxiliary pattern is parallel to the centerline of the selected pattern. A method of forming a pattern as claimed in claim 12, wherein the auxiliary pattern comprises at least one opening. The method of forming a pattern according to claim 12, wherein the first strip pattern and the second strip pattern both extend in a first direction and are disposed in parallel along a second direction, one of the second strip patterns The center line is parallel to the first direction, and the first direction is perpendicular to the second direction. The method of forming a pattern according to claim 17, wherein a width of a section of the auxiliary pattern along the second direction is less than a specific value, which is a maximum size of a pattern in the mask that is not exposed. . A method of forming a pattern as claimed in claim 18, wherein the specific value is substantially 32 nanometers (nm). The method of forming a pattern as claimed in claim 17, wherein the auxiliary pattern comprises a plurality of openings, and the openings are disposed at non-equal intervals along the second direction.