Photomask for eliminating antenna effects in an integrated circuit and integrated circuit manufacture with same

• US 6,978,437 B1
• Filed: 03/20/2003
• Issued: 12/20/2005
• Est. Priority Date: 10/10/2000
• Status: Expired due to Fees

• Current Assignee: Celerics Technologies Corporation
• Original Assignee: Toppan Photomasks Incorporated (TOPPAN Holdings, Inc.)
• Inventors: Rittman, Danny, Oren, Micha
• Primary Examiner(s): Smith, Matthew
• Assistant Examiner(s): Kik, Phallaka
• Application Number:
  US10/393,687
• Time in Patent Office: 1,006 Days
• Field of Search: 716/21, 716/10, 700/120, 700/121, 378/35, 430/5, 250/492.3, 382/144
• US Class Current: 257/659
• CPC Class Codes: G03F 1/36 Masks having proximity correction features; Preparation thereof, e.g. optical proximity correction [OPC] design processes
• CPC Class Codes: G06F 30/398 Design verification or optimisation, e.g. using design rule check [DRC], layout versus schematics [LVS] or finite element methods [FEM] optical proximity correction [OPC] design processes G03F1/36

Abstract

A photomask for eliminating antenna effects in an integrated circuit and integrated circuit manufactured with the photomask are disclosed. The photomask includes a substrate and a patterned layer formed on at least a portion of the substrate. The patterned layer may be formed using a mask pattern file created by analyzing a pattern in a mask layout file to identify a region including an antenna ratio less than a first design rule. A feature located in the identified region is moved based on a second design rule from a first position to a second position in the mask layout file to create a space in the identified region. A grounding feature is placed in the space and automatically connected to a gate feature in the mask layout file such that the antenna ratio is increased to greater than or approximately equal to the first design rule.

Claims

1. A photomask, comprising:

a substrate; and

a patterned layer formed on at least a portion of the substrate, the patterned layer formed using a mask pattern file created by;

analyzing a pattern in a mask layout file to identify a region including an antenna ratio less than a first design rule;

moving a feature located in the identified region from a first position to a second position in the mask layout file to create a space in the identified region for placing a grounding feature, the second position selected by using a second design rule to prevent a physical layout violation from being created when moving the feature from the identified region;

placing the grounding feature in the space; and

automatically connecting the grounding feature to a gate feature in the mask layout file such that the antenna ratio is increased to greater than or approximately equal to the first design rule.

2. The photomask of claim 1, wherein the antenna ratio comprises a ratio of a polysilicon over diffusion area to a polysilicon over field area.

3. The photomask of claim 1, wherein the antenna ratio comprises a ratio of a polysilicon over diffusion area to a metal over field area.

4. The photomask of claim 1, wherein connecting the grounding feature to the gate feature comprises:

creating a break in a polysilicon feature connected to the gate feature, the break separating the polysilicon feature and the gate feature; and

connecting the gate feature and the polysilicon feature with a metal feature.

5. The photomask of claim 1, wherein the grounding feature comprises a diffusion diode.

6. The photomask of claim 5, wherein connecting the grounding feature to the gate feature comprises connecting the diffusion diode to a metal feature connected to the gate feature.

7. The photomask of claim 1, wherein moving the feature comprises maintaining connectivity associated with the moved feature.

8. The photomask of claim 1, further comprising the patterned layer formed by compacting the pattern in the mask layout file in order to move the feature.

9. The photomask of claim 1, wherein moving the feature comprises moving the feature from a first layer to a second layer.

10. The photomask of claim 1, further comprising the patterned layer formed by:

placing the grounding feature outside of the identified region; and

creating an electrical connection from the grounding feature to the gate feature in order to maintain connectivity.

11. A photomask assembly, comprising:

a pellicle assembly defined in part by a pellicle frame and a pellicle film attached thereto; and

a photomask coupled to the pellicle assembly opposite from the pellicle film, the photomask including a patterned layer formed on a substrate, the patterned layer formed using a mask pattern file created by;

analyzing a pattern in a mask layout file to identify a region including an antenna ratio less than a first design rule;

moving a feature located in the identified region from a first position to a second position in the mask layout file to create a space in the identified region for placing a grounding feature, the second position selected by using a second design rule to prevent a physical layout violation from being created when moving the feature from the identified region;

placing the grounding feature in the space; and

automatically connecting the grounding feature to a gate feature in the mask layout file such that the antenna ratio is increased to greater than or approximately equal to the first design rule.

12. The photomask assembly of claim 11, wherein the antenna ratio comprises a ratio of a polysilicon over diffusion area to a polysilicon over field area.

13. The photomask assembly of claim 11, wherein the antenna ratio comprises a ratio of a polysilicon over diffusion area to a metal over field area.

14. The photomask assembly of claim 11, wherein the grounding feature comprises a diffusion diode.

15. The photomask assembly of claim 11, wherein moving the feature comprises maintaining connectivity associated with the moved feature.

16. The photomask assembly of claim 11, further comprising the patterned layer formed by compacting the pattern in the mask layout file in order to move the feature.

17. An integrated circuit formed on a semiconductor wafer, comprising:

a plurality of interconnect layers selected from a group consisting of n-well, p-well, diffusion, polysilicon and metal; and

a plurality of contact layers operable to provide electrical connections between the interconnect layers;

the interconnect and contact layers formed on a semiconductor wafer using a plurality of photomasks created by;

analyzing a pattern in a mask layout file to identify a region including an antenna ratio less than a first design rule;

moving a feature located in the identified region from a first position to a second position in the mask layout file to create a space in the identified region for placing a grounding feature, the second position selected by using a second design rule to prevent a physical layout violation from being created when moving the feature from the identified region;

placing the grounding feature in the space; and

automatically connecting the grounding feature to a gate feature in the mask layout file such that the antenna ratio is increased to greater than or approximately equal to the first design rule.

18. The integrated circuit of claim 17, wherein the antenna ratio comprises a ratio of a polysilicon over diffusion area to a polysilicon over field area.

19. The integrated circuit of claim 17, wherein the antenna ratio comprises a ratio of a polysilicon over diffusion area to a metal over field area.

20. The integrated circuit of claim 17, wherein moving the feature comprises maintaining connectivity associated with the moved feature.

21. The integrated circuit of claim 17, further comprising the interconnect and contact layers formed by compacting the pattern in the mask layout file in order to move the feature.

22. The integrated circuit of claim 17, further comprising the interconnect and contact layers formed by:

placing the grounding feature outside of the identified region; and

creating an electrical connection from the grounding feature to the gate feature in order to maintain connectivity.