CN212135137U - Layout structure of dynamic random access memory - Google Patents

Abstract

The utility model discloses a domain structure of DRAM, including a plurality of word line patterns, a plurality of active area patterns and a plurality of contact pattern. The word line patterns extend in a first direction and are arranged in parallel in a second direction. The active region pattern intersects the two word line patterns to be divided into a middle portion and two end portions. The intermediate portion is shaped as a parallelogram including a pair of obtuse angles and a pair of acute angles. The contact pattern overlaps a middle portion of the active region pattern and includes a pair of first edges parallel to the first direction and a pair of second edges between the first edges, wherein the second edges include a step shape. An object of the utility model is to promote the margin of the cutting technology and/or the bit line contact plug technology in active area to promote the cutting degree of accuracy in active area and/or reduce the defect that takes place the short circuit between bit line (bit line) and the adjacent storage node contact plug (storage node contact), promote the product yield.

Description

Layout structure of dynamic random access memory

Technical Field

The utility model relates to the field of semiconductor technology, in particular to layout structure of dynamic random access memory.

Background

A Dynamic Random Access Memory (DRAM), which belongs to a volatile memory, includes an array area (array area) composed of a plurality of memory cells (memory cells) and a peripheral area (peripheral area) composed of a control circuit. Each memory cell includes a transistor (transistor) electrically connected to a capacitor (capacitor), and the transistor controls the storage or release of charge in the capacitor to achieve the purpose of storing data. The control circuit is positioned to each memory cell to control the data access thereof by a Word Line (WL) and a Bit Line (BL) crossing the array region and electrically connected to the memory cells.

In advanced semiconductor processes, the layout pattern of the memory is becoming more and more compact to achieve higher integration density per unit area, but this not only increases the difficulty of manufacturing, but also makes the memory device more and more tolerant to manufacturing process variations, which may cause device electrical anomalies in the process variations of the critical steps. For example, in an active region cut (active region cut) process, the size of the cut active region is often shifted due to the deformation of the opening pattern. In addition, in the current dram adopting the buried word line (buried word line) structure, the bit line (bit line) and the adjacent storage node contact (storage node contact) are often short-circuited due to insufficient recess of the active region of the bit line contact, which causes abnormal memory function.

SUMMERY OF THE UTILITY MODEL

An object of the utility model is to provide a layout structure of Dynamic Random Access Memory (DRAM) and a manufacturing method for the photomask of dynamic random access memory technology can promote the margin of the cutting technology and/or the bit line contact plug technology in active area to promote the cutting degree of accuracy in active area and/or reduce the defect that takes place the short circuit between bit line (bit line) and the adjacent storage node contact plug (storage node contact), promote the product yield.

To achieve the above objective, an embodiment of the present invention provides a layout structure of a dynamic random access memory, which includes a plurality of word line patterns, a plurality of active region patterns, and a plurality of contact patterns. The word line patterns extend in a first direction and are arranged in parallel in a second direction. Each active region pattern intersects with two word line patterns to be divided into a middle portion and two end portions, wherein the middle portion is in the shape of a parallelogram and comprises a pair of obtuse angles and a pair of acute angles. The contact pattern overlaps the middle portion of the active region pattern and includes a pair of first edges parallel to a first direction and a pair of second edges between the first edges, the second edges including a stepped shape.

To achieve the above objects, another embodiment of the present invention provides a method for fabricating a photomask for a dynamic random access memory process, comprising the following steps. First, a layout structure including a plurality of word line patterns, a plurality of active region patterns, and a plurality of first contact patterns is received. The word line patterns extend along a first direction and are arranged in parallel along a second direction, and the first direction is perpendicular to the second direction. The active region pattern intersects the two word line patterns to be divided into a middle portion and two end portions, and the shape of the middle portion includes a parallelogram and includes a pair of obtuse angles and a pair of acute angles. The first contact pattern overlaps the middle portion of the active region pattern and includes a pair of first edges parallel to a first direction and a pair of second edges between the first edges. Then, a reshaping process is performed on the plurality of first contact patterns to obtain a plurality of second contact patterns, wherein the reshaping process comprises arranging an extension auxiliary pattern at a position of the second edge adjacent to the acute angle. Then, the second contact patterns are transferred to a photomask.

To achieve the above objective, another embodiment of the present invention provides a layout structure of a dynamic random access memory, which includes a plurality of word line patterns, a plurality of active region patterns, and a plurality of opening patterns. The word line patterns extend in a first direction and are arranged in parallel in a second direction. The word line pattern and the active region pattern include a plurality of overlapping regions having a shape of a parallelogram and including a pair of obtuse angles and a pair of acute angles. The opening patterns overlap some of the overlapping regions, each opening pattern including a pair of first edges parallel to the first direction and a pair of second edges between the first edges, the second edges including a stepped shape.

To achieve the above objects, another embodiment of the present invention provides a method for fabricating a photomask for a dynamic random access memory process, comprising the following steps. First, a layout structure including a plurality of word line patterns, a plurality of active region patterns, and a plurality of first opening patterns is received. The word line patterns extend in a first direction and are arranged in parallel in a second direction. The word line pattern and the active region pattern include a plurality of overlapping regions having a shape of a parallelogram and including a pair of obtuse angles and a pair of acute angles. The first pattern of openings overlaps some of the overlapping regions, each pattern of openings including a pair of first edges parallel to the first direction and a pair of second edges between the first edges. Then, a reshaping process is carried out on the plurality of first opening patterns to obtain a plurality of second opening patterns, wherein the reshaping process comprises the step of arranging an extension auxiliary pattern at the position, adjacent to the acute angle, of the second edge. Then, the second opening patterns are transferred to a photomask.

Drawings

To facilitate understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the figures, and it is contemplated that elements disclosed in one embodiment may be utilized in other embodiments without specific recitation. Unless specifically stated otherwise, the drawings herein are not to be understood as drawn to scale, and the drawings are generally simplified and omit details or elements for clarity of presentation and explanation, while the drawings herein and detailed description serve to explain the principles discussed below and to refer to like elements with similar reference numerals.

Fig. 1 is a flowchart illustrating a method for fabricating a photomask for a dram process according to an embodiment of the present invention.

Fig. 2, fig. 3 and fig. 4 are schematic partial plan views illustrating layout structures of a dram according to an embodiment of the present invention.

Fig. 5 is a partial schematic plan view of a photomask for a dram process according to an embodiment of the present invention.

Fig. 6 is a flowchart illustrating a method for fabricating a photomask for a dram process according to an embodiment of the present invention.

Fig. 7 is a partial plan view illustrating a layout structure of a dram according to an embodiment of the present invention.

Fig. 8 is a partial schematic plan view of a photomask for a dram process according to an embodiment of the present invention.

Fig. 9 and 10 are partial plan views illustrating layout structures of dram according to some embodiments of the present invention.

Fig. 11 is a flowchart illustrating a method of fabricating a photomask for a dram process according to an embodiment of the present invention.

Fig. 12, fig. 13 and fig. 14 are schematic partial plan views illustrating layout structures of a dram according to an embodiment of the present invention.

Fig. 15 is a partial schematic plan view of a photomask for a dram process according to an embodiment of the present invention.

Wherein the reference numerals are as follows:

10 layout structure

11 isolation region pattern

11' isolation region

12 word line pattern

14 active region pattern

14' active region pattern

14a intermediate part

14b end part

16 first contact pattern

16a first edge

16b second edge

20 second contact pattern

20a first edge

20b second edge

18 extended auxiliary pattern

22 concave auxiliary pattern

26 first opening pattern

26a first edge

26b second edge

28 second opening pattern

28a first edge

28b second edge

100 photo mask

120 photo mask pattern

500 photo mask

520 photo mask pattern

200 method for making

202 step

Step 204

206 step

300 method of manufacture

302 step

304 step

306 step

400 manufacturing method

402 step

404 step

406 step

D1 first direction

D2 second direction

Third direction D3

Acute angle of alpha

Beta obtuse angle

Detailed Description

The following detailed description and the accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. These embodiments are provided with sufficient detail to enable those skilled in the art to fully understand and practice the invention. The embodiments described below are capable of structural, logical, and electrical changes, such as substitutions, rearrangements, and combinations of features from several different embodiments, and may be employed in other embodiments without departing from the spirit of the disclosure.

The present invention discloses a layout structure of dynamic random access memory and a method for manufacturing a photomask, wherein one of the implementation modes can be applied to the manufacturing process of bit line contact recess (bit line contact access). Please refer to fig. 1 to 5. Fig. 1 is a flow chart illustrating a method 200 for fabricating a photomask for a dram process according to an embodiment of the present invention. Fig. 2, fig. 3 and fig. 4 are schematic partial plan views illustrating layout structures of a dram in the steps of the manufacturing method 200 according to an embodiment of the present invention. Fig. 5 is a partial schematic plan view of a photomask for a dram process according to an embodiment of the present invention. The method 200 includes using a computer system that receives a tape-out layout structure and modifies the pattern of the layout structure according to rules set by the characteristics of the semiconductor fabrication process, and then transfers the modified layout structure to a photomask fabrication system to fabricate a photomask for the semiconductor fabrication process.

As shown in FIG. 1, the method 200 begins with receiving a layout structure at step 202. As shown in fig. 2, the layout structure 10 includes a plurality of word line patterns 12, a plurality of active region patterns 14, and a plurality of first contact patterns 16. The word line pattern 12, the active area pattern 14 and the first contact pattern 16 belong to different pattern layers of the layout structure 10 to be transferred to different photomasks as photomask patterns, respectively used in different patterning steps of a dynamic random access memory process to form a dynamic random access memory structure on a semiconductor substrate. In particular, the portions other than the active region pattern 14 are the isolation region patterns 11, and are transferred onto the same photomask together with the active region pattern 14.

The word line patterns 12 extend in the first direction D1 and are arranged in parallel in the second direction D2. The active region patterns 14 extend in the third direction D3 and are arranged in parallel along the first direction D1, and adjacent active region patterns 14 are staggered in the first direction D1. In one embodiment, the first direction D1 and the second direction D2 are perpendicular to each other, and the third direction D3 is not parallel to the first direction D1 and the second direction D2. For example, the third direction D3 and the first direction D1 include an included angle therebetween that is less than 90 degrees.

Each active region pattern 14 intersects two adjacent word line patterns 12 to be divided into two end portions 14b and one middle portion 14a between the two end portions 14b by the word line patterns 12. When the active region pattern 14 is transferred onto a semiconductor substrate, the middle portion 14a is a region electrically connected to a bit line contact (bit line contact), and the end portion 14b is a region electrically connected to a storage node contact (storage node contact).

In the present embodiment, the shape of the intermediate portion 14a includes a parallelogram, and includes a pair of acute angles α and a pair of obtuse angles β. The acute angle alpha is smaller than the obtuse angle beta.

The first contact pattern 16 overlaps the middle portion 14a of the active region pattern 14, and includes a pair of first edges 16a parallel to the first direction D1 and a pair of second edges 16b between the first edges 16 a. In an embodiment, the first contact pattern 16 may include a rectangular plane shape, that is, the second edge 16b is parallel to the second direction D2, and the first edge 16a and the second edge 16b are perpendicular to each other. In one embodiment, the first contact pattern 16 may include a pair of corners that are coterminous with the acute angle α of the middle portion 14a of the active region pattern 14. In other embodiments, the first contact pattern may be a parallelogram, such as a parallelogram with a first edge parallel to the first direction D1 and a second edge parallel to the third direction D3.

In order to compensate for pattern distortions and/or to increase process tolerance caused by the patterning step, the dynamic random access memory fabrication process can be improved in terms of process window (process window) tolerance to process variations by individually modifying each pattern layer before transferring it to the photomask to obtain desirable imaging results on the semiconductor substrate.

In detail, as shown in fig. 1, the manufacturing method 200 proceeds to step 204, where a reshaping process is performed on the plurality of first contact patterns to obtain a plurality of second contact patterns. In an embodiment, as shown in fig. 3 and 4, the reshaping process may include extending the second edges 16b of the first contact patterns 16 along the second direction D2, partially overlapping the first contact patterns 16 with the word line patterns 12 on both sides, and respectively disposing the extension assistance patterns 18 at positions where the two second edges 16b are adjacent to the acute angle α. The extended auxiliary pattern 18 and the first contact pattern 16 are coherent (tone), such as dark (dark) or clear (clear), and are combined to obtain the second contact pattern 20. It should be noted that the present invention is not limited to the order of the operation of extending the second edge 16b and the operation of setting the extension assistance pattern 18. For example, the second edge 16b may be extended and then the auxiliary stretching pattern 18 may be provided, or the auxiliary stretching pattern 18 may be provided and then the second edge 16b may be extended and the auxiliary stretching pattern 18 may be simultaneously extended.

As shown in fig. 4, the extension assistance pattern 18 may include a rectangular planar shape having a pair of edges parallel to the first direction D1 and another pair of edges parallel to the second direction D2. In one embodiment, one of the pair of edges parallel to the first direction D1 is aligned with the first edges 16a of the first contact patterns 16, and the other is interposed between the first edges 16a of the first contact patterns 16 and connected to the second edges 16b of the first contact patterns 16. The extension auxiliary pattern 18 is located between the first contact pattern 16 and the adjacent end portion 14b, and preferably, the extension auxiliary pattern 18 does not overlap the adjacent end portion 14 b.

The second contact pattern 20 composed of the first contact pattern 16 and the extension assistance pattern 18 includes a planar shape of a Z-shape. In detail, the second contact pattern 20 includes a pair of first edges 20a parallel to the first direction D1 and a pair of second edges 20b between the first edges 20 a. The first edge 20a includes an offset in the second direction D2. The second edge 20b includes a stepped shape formed by the second edge 16b of the first contact pattern 16 and the edge of the extension auxiliary pattern 18.

The second contact pattern 20 completely overlaps the middle portion 14a of the active region 14, partially overlaps the word line patterns 12 on both sides, and also partially overlaps the isolation region 11' between the middle portion 14a and the adjacent end portion 14 b. The area of the extension auxiliary pattern 18 may be adjusted to meet the overlapping area of the second contact pattern 20 and the isolation region 11'. For example, in some embodiments, the overlapping area of the second contact pattern 20 and the isolation region 11 'is approximately between 40% and 50% of the area of the isolation region 11'.

It should be particularly noted that, in another embodiment, the layout structure 10 received in step 202 may be, for example, as shown in fig. 3, wherein the first contact pattern 16 is already partially overlapped with the word line patterns 12 on both sides before the reshaping process in step 204. In this case, the reshaping process of step 204 may omit the operation of extending the second edge 16b of the first contact pattern 16.

Then, in step 206, the second contact patterns are transferred to a photomask to form a photomask pattern. The photomask may be fabricated using techniques known in the art. For example, the data of the second contact pattern 20 may be output to a laser exposure system and the photomask substrate may be patterned according to the second contact pattern 20, obtaining the photomask 100 as shown in FIG. 5, which includes the photomask pattern 120 transferred from the second contact pattern 20.

The photomask 100 is to be used in a process of manufacturing a bit line contact recess (bit line contact recess) of a Dynamic Random Access Memory (DRAM). For example, after defining the active area and word line of the dynamic random access memory in the semiconductor substrate, an insulating layer is formed on the semiconductor substrate, and then a mask layer, such as a photoresist, is formed on the insulating layer. Then, the mask layer is patterned by using the mask 100 to transfer the mask pattern 120 into the mask layer, so as to form an opening in the mask layer corresponding to the middle portion of the active region. Then, the semiconductor substrate exposed from the mask layer is etched by using the mask layer as an etching mask to form a bit line contact plug recess.

Please refer to fig. 6, fig. 2, fig. 3, fig. 7 and fig. 8. Fig. 6 is a flowchart illustrating a method 300 for fabricating a photomask for a dram process according to another embodiment of the present invention. Fig. 2, fig. 3 and fig. 7 are schematic partial plan views illustrating layout structures of a dram in the steps of the manufacturing method 300 according to an embodiment of the present invention. Fig. 8 is a partial schematic plan view of a photomask for a dram process according to an embodiment of the present invention. Specifically, the main difference between the fabrication method 300 of fig. 6 and the fabrication method 200 of fig. 1 is that the reshaping process (step 304) of the fabrication method 300 further includes providing a concave auxiliary pattern at a position where the second edge is adjacent to the obtuse angle of the middle portion of the active region.

As shown in FIG. 6, the method 300 begins with receiving a layout structure at step 302. Referring to fig. 2, the layout structure 10 includes a plurality of word line patterns 12, a plurality of active region patterns 14, and a plurality of first contact patterns 16. The word line patterns 12 extend in the first direction D1 and are arranged in parallel in the second direction D2. The active region patterns 14 extend in the third direction D3 and are arranged in parallel along the first direction D1, and adjacent active region patterns 14 are staggered in the first direction D1. Each active region pattern 14 intersects two adjacent word line patterns 12 to be divided by the word line patterns 12 into two end portions 14b and one intermediate portion 14a located between the two end portions 14b, wherein the shape of the intermediate portion 14a includes a parallelogram and includes a pair of acute angles α and a pair of obtuse angles β. The first contact pattern 16 overlaps the middle portion 14a of the active region pattern 14, and includes a pair of first edges 16a parallel to the first direction D1 and a pair of second edges 16b between the first edges 16 a.

Then, in step 304, a reshaping process is performed on the plurality of first contact patterns to obtain a plurality of second contact patterns. In one embodiment, as shown in fig. 3 and 7, the reshaping process of step 304 includes extending the second edges 16b of the first contact patterns 16 along the second direction D2, making the first contact patterns 16 partially overlap the word line patterns 12 on both sides, and respectively providing the extension auxiliary patterns 18 at positions where the two second edges 16b are adjacent to the acute angle α, and providing the recess auxiliary patterns 22 at positions where the second edges 16b are adjacent to the obtuse angle β. The extended auxiliary patterns 18 and the first contact patterns 16 are in-tone (tone), and the recessed auxiliary patterns 22 and the first contact patterns 16 are in-tone (reverse tone). For example, the extended auxiliary pattern 18 and the first contact pattern 16 are dark regions (dark), and the recessed auxiliary pattern 22 is a bright region (clear). Alternatively, the extended auxiliary pattern 18 and the first contact pattern 16 are bright areas (clear), and the recessed auxiliary pattern 22 is dark areas (dark). The extension auxiliary patterns 18, the recess auxiliary patterns 22 are combined with the first contact patterns 16 to obtain the second contact patterns 20.

The present invention does not limit the order of the operation of extending the second edge 16b and the operation of providing the extension auxiliary pattern 18 and the operation of providing the recess auxiliary pattern 22. For example, the second edge 16b may be extended and then the protrusion auxiliary patterns 18 and the depression auxiliary patterns 22 may be simultaneously disposed, or the protrusion auxiliary patterns 18 and the depression auxiliary patterns 22 may be disposed first and then the second edge 16b may be extended and the auxiliary patterns 18 and the depression auxiliary patterns 22 may be simultaneously extended. In another embodiment, when the layout structure 10 received in step 302 is the layout structure 10 shown in fig. 3 in which the first contact pattern 16 has been partially overlapped with the word line patterns 12 on both sides before the reshaping process in step 304, the reshaping process in step 304 may omit the operation of extending the second edge 16b of the first contact pattern 16.

As shown in fig. 7, the extended auxiliary patterns 18 and the recessed auxiliary patterns 22 may have a rectangular planar shape, respectively, having a pair of edges parallel to the first direction D1 and another pair of edges parallel to the second direction D2. In one embodiment, one of the pair of edges of the extended auxiliary pattern 18 parallel to the first direction D1 is aligned with the first edges 16a of the first contact patterns 16, and the other is interposed between the first edges 16a of the first contact patterns 16 and connected to the second edges 16b of the first contact patterns 16. One of the pair of edges of the concave auxiliary pattern 22 parallel to the first direction D1 is aligned with the other first edge 16a of the first contact pattern 16, and the other is interposed between the first edges 16a of the first contact patterns 16 and connected to the second edges 16b of the first contact patterns 16. The extension auxiliary pattern 18 is located between the first contact pattern 16 and the adjacent end portion 14b, and preferably, the extension auxiliary pattern 18 does not overlap the adjacent end portion 14b, and the recess auxiliary pattern 22 does not overlap the middle portion 14 a.

The second contact pattern 20, which is composed of the first contact pattern 16, the extension auxiliary pattern 18, and the depression auxiliary pattern 22, includes a planar shape of a Z-shape. In detail, the second contact pattern 20 includes a pair of first edges 20a parallel to the first direction D1 and a pair of second edges 20b between the first edges 20 a. The first edge 20a includes an offset in the second direction D2. The second edge 20b includes a stepped shape formed by the second edge 16b of the first contact pattern 16, the edge of the extension auxiliary pattern 18, and the edge of the depression auxiliary pattern 22. Similarly, the areas of the extension auxiliary patterns 18 and the recess auxiliary patterns 22 may be adjusted to meet the overlapping area of the second contact patterns 20 and the isolation regions 11'.

Next, in step 306, the second contact patterns are transferred to a photomask to form a photomask pattern. As shown in fig. 8, the photomask 100 including the photomask pattern 120 transferred from the second contact pattern 20 is to be used in a process of manufacturing a bit line contact recess (bit line contact recess) of a Dynamic Random Access Memory (DRAM).

Referring to fig. 9 and 10, schematic partial plan views of layout structures of dynamic random access memories according to some embodiments of the present invention are shown, wherein the same or corresponding elements as in the previous embodiments are indicated by the same reference numerals. The shapes of the extension auxiliary patterns 18 and the recess auxiliary patterns 22 of the present invention are not limited to the rectangular shapes shown in fig. 4 and 7, but may include other shapes, for example, the planar shapes shown in fig. 9 may include stepped shapes, or the planar shapes shown in fig. 10 may include triangular shapes, but are not limited thereto.

In the present embodiment, the extension auxiliary patterns 18 are disposed at positions of the first contact patterns 16 corresponding to acute angles α of the middle portion 14a of the active region 14, and the recess auxiliary patterns 22 are selectively disposed at positions corresponding to obtuse angles β of the middle portion 14a of the active region 14, so that the second contact patterns 20 can compensate for the rounding of the opening pattern caused by the optical effect in the process of forming the recess of the line contact plug of the dram, thereby ensuring that the recess of the bit line contact plug can recess the middle portion 14a of the active region 14 to a sufficient depth, and reducing the problem of short circuit between the bit line and the adjacent storage node contact plug due to insufficient recess of the bit line contact plug.

One embodiment of the layout structure of the dynamic random access memory and the method for manufacturing the photo mask of the present invention can be applied to an active region cut (active region cut) process. Please refer to fig. 11 to fig. 15. Fig. 11 is a flowchart illustrating a method 400 for fabricating a photomask for a dram process according to an embodiment of the present invention. Fig. 12, fig. 13 and fig. 14 are partial schematic plan views illustrating layout structures of a dram in the steps of the manufacturing method 400 according to an embodiment of the present invention. Fig. 15 is a partial schematic plan view of a photomask for a dram process according to an embodiment of the present invention. The fabrication method 400 includes using a computer system that receives a tape-out layout structure and modifies the pattern of the layout structure according to rules set by the characteristics of the semiconductor fabrication process, and then transfers the modified layout structure to a photomask fabrication system to fabricate a photomask for the semiconductor fabrication process.

As shown in FIG. 11, the method 400 begins with receiving a layout structure at step 402. As shown in fig. 12, the layout structure 10 includes a plurality of word line patterns 12, a plurality of active region patterns 14', and a plurality of first opening patterns 26. It is noted that the active area pattern 14 'of the present embodiment has been adjusted to a continuous pattern extending along the third direction D3 according to the requirements of the active area cutting (active area cut) process, and the opening pattern 26 defines the cutting area of the active area pattern 14'. The word line pattern 12, the active area pattern 14' and the first opening pattern 26 belong to different pattern layers of the layout structure 10 and are to be transferred to different photomasks as photomask patterns, which are respectively used in different patterning steps of the dram process.

The word line patterns 12 extend in the first direction D1 and are arranged in parallel in the second direction D2. The active region patterns 14' extend along the third direction D3 and are arranged in parallel along the first direction D1. In one embodiment, the first direction D1 and the second direction D2 are perpendicular to each other, and the third direction D3 is not parallel to the first direction D1 and the second direction D2. For example, the third direction D3 and the first direction D1 include an included angle therebetween that is less than 90 degrees.

The word line pattern 12 and the active region pattern 14' will intersect and include a plurality of overlapping regions that are shaped as parallelograms and include a pair of acute angles alpha and a pair of obtuse angles beta. The first opening patterns 26 overlap some of the overlapping regions of the word line patterns 12 and the active region patterns 14'. In detail, the active area pattern 14 'is divided into end portions 14b and a middle portion 14a between the end portions 14b by the word line pattern 12, and the first opening pattern 26 overlaps with an overlapping area of the word line pattern 12 and the active area pattern 14' between the end portions 14 b.

The first opening pattern 26 includes a pair of first edges 26a parallel to the first direction D1 and a pair of second edges 26b between the first edges 26 a. In one embodiment, the first opening pattern 26 may include a rectangular planar shape, that is, the second edge 26b is parallel to the second direction D2, and the first edge 16a and the second edge 16b are perpendicular to each other. In one embodiment, the first opening pattern 26 may include a diagonal line that is coterminous with the acute angle α of the overlapping region of the word line pattern 12 and the active region pattern 14'. In other embodiments, the first contact pattern may be a parallelogram, such as a parallelogram with a first edge parallel to the first direction D1 and a second edge parallel to the third direction D3.

The method 400 then proceeds to step 404, where a reshaping process is performed on the plurality of first opening patterns to obtain a plurality of second opening patterns. In an embodiment, as shown in fig. 13 and 14, the reshaping process may include extending the first edges 26a of the first opening patterns 26 along the first direction D1, and respectively disposing the extension assistance patterns 18 at positions where the two second edges 26b are adjacent to the acute angle α, and optionally respectively disposing the recess assistance patterns 22 at positions where the two second edges 26b are adjacent to the obtuse angle β. The extension auxiliary patterns 18 and the first opening patterns 26 are in the same tone (tone), and the recess auxiliary patterns 22 and the first opening patterns 26 are in the opposite tone (reverse tone). For example, in one embodiment, the extension auxiliary pattern 18 and the first opening pattern 26 are dark regions (dark), and the recess auxiliary pattern 22 is clear regions (clear). In another embodiment, the extended auxiliary pattern 18 and the first opening pattern 26 are clear areas (clear), and the recessed auxiliary pattern 22 is dark areas (dark). The extension auxiliary pattern 18, the recess auxiliary pattern 22, and the first opening pattern 26 are combined to obtain a second opening pattern 28. It should be noted that the present invention is not limited to the order of the operation of extending the first edge 26a and the operation of disposing the extension auxiliary pattern 18 and the recess auxiliary pattern 22. For example, the first edge 26a may be extended and then the protruding auxiliary patterns 18 and the recessed auxiliary patterns 22 may be disposed, or the protruding auxiliary patterns 18 and the recessed auxiliary patterns 22 may be disposed and then the first edge 26a may be extended and the auxiliary patterns 18 may be simultaneously extended.

As shown in fig. 14, the extended auxiliary patterns 18 and the recessed auxiliary patterns 22 may have a rectangular planar shape, respectively, having a pair of edges parallel to the first direction D1 and another pair of edges parallel to the second direction D2. In one embodiment, one of the pair of edges of the extension auxiliary pattern 18 parallel to the first direction D1 is aligned with the first edges 26a of the first opening patterns 26, and the other is interposed between the first edges 26a of the first opening patterns 26 and connected to the second edges 26b of the first opening patterns 26. One of the pair of edges of the concave auxiliary pattern 22 parallel to the first direction D1 is aligned with the other first edge 26a of the first opening pattern 26, and the other is interposed between the first edges 26a of the first opening pattern 26 and connected to the second edge 26b of the first opening pattern 26. The extension auxiliary pattern 18 is located between the first opening pattern 26 and the adjacent active region 14 ', preferably, the extension auxiliary pattern 18 does not overlap the adjacent active region 14 ', and the recess auxiliary pattern 22 does not overlap the overlapping region of the word line pattern 12 and the active region pattern 14 '. The areas of the extension auxiliary patterns 18 and the recess auxiliary patterns 22 may be adjusted to meet the overlapping area of the second opening patterns 28 and the isolation regions 11.

The second opening pattern 28 includes a planar shape of a Z-shape. In detail, the second opening pattern 28 includes a pair of first edges 28a parallel to the first direction D1 and a pair of second edges 28b between the first edges 28 a. The first edge 28a overlaps the active region pattern 14' and does not overlap the word line pattern 12. The second edge 28b does not overlap the active region pattern 14' and overlaps the word line pattern 12. The first edge 28a includes an offset in the second direction D2. The second edge 28b includes a stepped shape formed by the second edge 26b of the first opening pattern 26, an edge of the extension auxiliary pattern 18, and an edge of the depression auxiliary pattern 22.

The shapes of the extension auxiliary patterns 18 and the depression auxiliary patterns 22 are not limited to the rectangle shown in fig. 14, but may include other shapes such as a step shape or a triangle, but are not limited thereto.

Then, in step 406, the plurality of second opening patterns are transferred to a photomask to form a photomask pattern. As shown in fig. 15, the photomask 500 includes a photomask pattern 520 transferred from the second opening pattern 28.

The photomask 500 is to be used in an active region cut (active region cut) process of a Dynamic Random Access Memory (DRAM). For example, a mask layer may be formed on a semiconductor substrate, the active region pattern 14' may be transferred into the mask layer by a photolithography process to form a patterned mask layer including a continuously extending active region pattern, and the continuously extending active region pattern of the patterned mask layer may be cut into a discontinuous active region pattern by transferring the photomask pattern 520 of the photomask 500 into the patterned mask layer by another photolithography process. Then, the semiconductor substrate is etched by using the patterned mask layer comprising the discontinuous active region pattern as an etching mask, and the discontinuous active region is defined on the semiconductor substrate.

In the present embodiment, the second opening pattern 28 is obtained by disposing the extension auxiliary pattern 18 at a position corresponding to the acute angle α of the overlapping area of the word line pattern 12 and the active area pattern 14 'in the first opening pattern 26, and optionally disposing the recess auxiliary pattern 22 at a position corresponding to the obtuse angle β of the overlapping area of the word line pattern 12 and the active area pattern 14', so as to compensate for the rounding of the opening pattern due to the optical effect in the active area cutting process of the dram, thereby ensuring the cutting accuracy of the active area.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (6)

1. A layout structure of a dynamic random access memory, comprising:

a plurality of word line patterns extending in a first direction and arranged in parallel in a second direction;

a plurality of active region patterns, each of which intersects with two of the word line patterns to be divided into a middle portion and two end portions, wherein the middle portion has a parallelogram shape including a pair of obtuse angles and a pair of acute angles; and

a plurality of contact patterns overlapping the middle portion of the active region pattern and including a pair of first edges parallel to the first direction and a pair of second edges between the first edges, the second edges including a stepped shape.

2. The layout structure of claim 1, wherein the active region patterns extend in a third direction and are staggered in the first direction, the third direction being non-parallel to the first direction and the second direction.

3. The layout structure according to claim 1, wherein an isolation region is included between a middle portion of the active region pattern and the end portion of an adjacent active region pattern, and the contact pattern overlaps 40% to 50% of an area of the isolation region.

4. The layout structure according to claim 1, wherein the shape of the contact pattern comprises a zigzag shape.

5. The layout structure of claim 1, wherein the first edges of the contact patterns are misaligned in the second direction.

6. The layout structure according to claim 1, wherein said contact pattern partially overlaps with both of said word line patterns.

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