JP2009271261A - Circuit structure and photomask for defining the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a circuit structure and a photomask for the circuit structure, the photomask pattern including lines and pickup pads that can be more easily corrected by OPC (optical proximity correction) than by conventional techniques. <P>SOLUTION: A circuit structure and a photomask for defining the circuit structure are provided. The circuit structure includes a plurality of pickup pads 320 and a plurality of lines 310 in parallel, in which a part of the lines contiguously arranged are each disposed with a pickup pad. The pickup pad of any line disposed with a pickup pad is connected, through a discontinuity point 330 of a neighboring line at one side of the line, to a next line. The photomask has thereon a plurality of line patterns for defining the above lines and a plurality of pickup pad defining patterns for defining the above pickup pads. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates generally to integrated circuit (IC) designs, and more particularly, to circuit structures applied to integrated circuit (IC) areas and optical proximity correction of patterns (OPC). The present invention relates to a photomask for defining a circuit structure that can be easily corrected by “correction”.

  In the current semiconductor process, a dog-bone pattern is usually employed as a photomask pattern for a line pickup region. In the circuit design of FIG. 1, the position of the pick-up pad pattern 120 for the line pattern 110 is between the dense region 12 and the isolated region 14. Due to the significant pattern density difference, it is difficult to control the optical proximity effect, and the optical proximity correction (OPC) process is complicated, as shown in FIG. Numerals 210 and 220 indicate a line pattern and a pickup pattern, respectively. Therefore, OPC usually has to be aided by a computer, thereby achieving a better correction effect.

  As the line width of the lithographic process has been reduced, the optical proximity effect becomes more severe with the development of lithographic techniques (eg shorter wavelengths of exposed light or higher numerical aperture). Therefore, the difficulty in OPC with a dogbone design is further increased, making it difficult to create a sufficiently large process window.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a circuit structure including a line and a pickup pad in which a corresponding photomask pattern can be more easily corrected by OPC as compared with the prior art.

  Another object of the present invention is to provide a photomask suitable for defining the circuit structure of the present invention. The OPC of the line pattern and pad definition pattern on the photomask is more easily applied compared to the prior art.

  The circuit structure of the present invention includes a plurality of parallel lines and a plurality of pickup pads. One pickup pad is arranged on each of a part of the continuously arranged lines. A pickup pad of an arbitrary line in which one pickup pad is arranged passes through a discontinuous point of an adjacent line on one side of the line and is connected to the next line. A local structure including such a pickup pad is specifically called an H-cut structure.

  The photomask of the present invention is for defining the circuit structure, and has a plurality of parallel line patterns and a plurality of pickup pad definition patterns. One pickup pad definition pattern is arranged in each of part of the line patterns arranged continuously. A pickup pad definition pattern of an arbitrary line pattern in which one pickup pad definition pattern is arranged passes through a discontinuous point of an adjacent line pattern on one side of the line pattern and is arranged between the next line pattern and the line pattern. Is done.

  In some embodiments, the line pattern and the pickup pad definition pattern are further corrected through OPC, especially in the context of smaller line widths. OPC is a simple symmetric OPC. In one embodiment, the pickup pad definition pattern is connected to the next line pattern and line pattern. The related OPC is, for example, reducing the size of the pickup pad definition pattern in the extending direction of the line pattern, the next line pattern located on both sides of the pickup pad definition pattern, and the inner boundary of the two parts of the line pattern, and Each of the outer boundaries protrudes outward, shrinks inward, and the next line pattern located on both sides of the pickup pad definition pattern, and two lines outside the two line patterns outside the line pattern, respectively. Including reducing the two inner boundaries of the two portions of the line pattern as well as the two outer boundaries together inward.

  In the H-cut structure of the present invention, since the pattern density around the pickup pad defining pattern is close to that of the dense region, the optical proximity effect is easier to control compared to the conventional dogbone design. Furthermore, since the H-cut structure has good symmetry, OPC can be performed more easily. Through computer simulation and experimentation, the same H-cut design process window of the present invention is made larger than that produced by dogbone pattern design under the same lithography conditions.

  That is, in the H-cut structure of the present invention, since the pattern density around the pickup pad is close to that of the dense region, the optical proximity effect is easier to control compared to the conventional dogbone design. Furthermore, since the H-cut structure has good symmetry, OPC is easy to execute. Through computer simulation and experimentation, it can be seen that, under the same conditions of the lithography process, the H-cut pattern design of the present invention can make the process window larger than that produced by the dogbone pattern design.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
FIG. 3 is a plan view showing a structure and design process of a plurality of line patterns in which pickup pad patterns are arranged according to an embodiment of the present invention.

  In FIG. 3, the pattern is designed as follows. First, a plurality of parallel line patterns 310 are defined, and a linear pattern serving as a photomask pattern of a line where a pickup pad needs to be arranged, and a dummy pattern (dummy patterns) where no pickup pad needs to be arranged, that is, , The rightmost three linear patterns in the figure are included. Since the dummy pattern provides a symmetrical pattern arrangement, OPC is further facilitated.

  Next, the pickup pad pattern 320 is arranged in each line pattern 310 where the pickup pad needs to be arranged, and the discontinuity 330 is located at the position of the adjacent line pattern 310 corresponding to the pickup pad pattern 320. Be placed. As an example, when the line pattern 310a requiring the arrangement of the pickup pad is given, the pickup pad pattern 320 passes through the discontinuous point 330 of the adjacent line pattern 310b on one side of the line pattern 310a, and the next line pattern Connected to 310c, an H-cut structure is formed. It should be noted that the adjacent line pattern 310b is not connected to the pickup pad pattern 320 of the line pattern 310a.

  In FIG. 3, if the process line width is sufficiently large, a circuit structure having a similar shape with a photomask pattern as shown in the figure can be defined, and a plurality of parallel structures corresponding to the line pattern 310 can be defined. A plurality of pickup pads corresponding to the line and pickup pad pattern 320 are included. Pickup pads are respectively arranged in a part of the continuously arranged lines, and the pickup pads of any line where the pickup pads are arranged pass through the discontinuous points of the lines connected on one side of the line, Connected to the next line, an H-cut structure corresponding to the H-cut structure 340 on the photomask is formed.

  However, when the line width is smaller, the line pattern 310 and the pickup pad pattern 320 are further corrected through OPC. Compared to the dogbone structure, the H-cut structure on the photomask has a good symmetry and a more uniform surrounding pattern density, so that the OPC can be a symmetric OPC that is easier to perform. As can be seen from the computer simulation, the desired effect is obtained only by performing manual OPC without computer aided correction.

  Specifically, the H-cut structure on the photomask can be corrected by partial cutting and / or other pattern correction methods, so that the image of the H-cut pattern has accurate focus / exposure conditions and reliable condition changes. And satisfy the standard, and ensure a sufficiently large process window.

  FIG. 4 shows an example (a) of OPC for forming a photomask pattern having an H-cut structure according to the present invention and a computer simulation (b) of a circuit structure defined by the photomask pattern corrected through OPC. It is a plane explanatory view.

  In FIG. 4A, a pickup pad definition pattern 412 is for defining a pickup pad of a line defined by the line pattern 410a, and passes through discontinuous points of the adjacent line pattern 410b, It is connected to the next line pattern 410c. The OPC process includes the following steps: The size of the pickup pad definition pattern 412 in the extending direction of the line pattern is reduced, and the next line pattern 410c and 2 of the line pattern 410a located on both sides of the pickup pad definition pattern 412 respectively. The two inner boundaries 414 and the two outer boundaries 416 of one part respectively project outward and shrink inward. In addition, two inner boundaries 418 of two portions of the two line patterns 410e outside the next line pattern 410c and two line patterns 410d outside the next line pattern 410c and two outside the line pattern 410a located on both sides of the pickup pad definition pattern 412, respectively. The two outer boundaries 420 are both reduced inward. The pattern transition result of the post OPC pattern obtained through computer simulation is shown in FIG. 4B, the line width is set to 0.25 μm, and the wavelength of the exposure light beam is 193 nm. .

  As described above, the present invention has been disclosed according to the best embodiment. However, this is not intended to limit the present invention and is within the scope of the technical idea of the present invention so that those skilled in the art can easily understand. Accordingly, appropriate changes and modifications can be naturally made, so that the scope of protection of the present invention is defined on the basis of the scope of claims and an area equivalent thereto.

It is a top view which shows the structure of the several line pattern which has arrange | positioned the pick-up pad in the conventional dogbone design. It is a top view which shows the result after the pick-up pad pattern in the conventional dogbone design and the near line pattern were correct | amended through OPC. It is a top view which shows the structure and design process of the several line pattern which has arrange | positioned the pick-up pad concerning embodiment of this invention. It is a top view which shows one example (a) which shows formation of the photomask pattern provided with the H cut structure of this invention, and computer simulation (b) of the circuit structure defined by the photomask pattern corrected through OPC.

Explanation of symbols

12 Dense area 14 Isolated area 110, 210, 310, 410 (a / b / c / d / e) Line pattern 120, 220, 320 Pickup pad pattern 330 Discontinuous point 340 H cut structure 412 Pickup pad definition pattern 414, 416 , 418, 420 Line pattern boundaries

Claims (6)

A circuit structure including a plurality of parallel lines and a plurality of pickup pads,
One pick-up pad is arranged on each part of the line arranged continuously;
A circuit structure in which the pickup pad of an arbitrary line on which one pickup pad is arranged passes through a discontinuous point of a line adjacent to one side of the line and is connected to the next line. A photomask comprising a plurality of parallel line patterns and a plurality of pickup pad definition patterns,
One pickup pad definition pattern is disposed in each of part of the line pattern arranged continuously;
Arbitrary pickup pad definition pattern in which one pickup pad definition pattern is arranged passes through a discontinuous point of the line pattern adjacent to one side of the line pattern, and is arranged between the next line pattern and the line pattern. Photomask that is what is to be done.   The photomask according to claim 2, wherein the line pattern and the pickup pad definition pattern are corrected through optical proximity correction (OPC).   The photomask according to claim 3, wherein the OPC is symmetric OPC.   The photomask according to claim 4, wherein the pickup pad definition pattern is connected to the next line pattern and the line pattern. The OPC associated with the pickup pad definition pattern is:
Reducing the size of the pickup pad defining pattern in the direction of extension of the line pattern;
An inner boundary and an outer boundary of the next line pattern and the two portions of the line pattern respectively located on both sides of the pickup pad defining pattern are projected outward and reduced inward;
Two inner boundaries and two outer boundaries of two portions of the two line patterns are both outside the next line pattern and the two line patterns outside the line pattern respectively located on both sides of the pickup pad definition pattern. The photomask according to claim 5, wherein the photomask is reduced inward.