Granted Patent B2

US 8,183,639 · App. 12/899,663 · Granted May 22, 2012

Abstract

Claims (74)

1. A dual port static random access memory cell having pull-down transistors, pull-up transistors, and pass transistors, comprising:

a first active region having a first pull-down transistor coupled to a first data node, a second pull-down transistor coupled to a complementary data node that is complementary to the first data node;

a first pass transistor coupled to the first data node, the first pass transistor having a current electrode coupled to a contact for contacting a first bit line, and a second pass transistor coupled to the complementary data node, the second pass transistor having a current electrode coupled to a contact for contacting a first complementary bit line for carrying data complementary to data carried by the first bit line;

a second active region having the same size and shape as the first active region having a third pull-down transistor coupled in parallel to the first-pull down transistor, a fourth pull-down transistor coupled in parallel to the second pull-down transistor; a third pass transistor coupled to the first data node, the third pass transistor having a current electrode coupled to a contact for contacting a second bit line, and a fourth pass transistor coupled to the complementary data node, the fourth transistor having a current electrode coupled to a contact for contacting a second complementary bit line for carrying data complementary to data carried by the second bit line; and

a first pull-up transistor and a second pull-up transistor located between the first and second active regions.

2. The dual port static random access memory cell of claim 1 , wherein:

the first pull-up transistor is located in a third active region and the second pull-up transistor is located in a fourth active region.

3. The dual port static random access memory cell of claim 1 , wherein the first data node comprises a first metal layer and a second data node comprises a second metal layer, wherein the first metal layer and the second metal layer have the same size and shape.

4. The dual port static random access memory cell of claim 1 , wherein:

the first pass transistor has a gate having a first extension to a first contact for contacting a first word line;

the second pass transistor has a gate having a second extension to a second contact for contacting the first word line; and

the first extension and the second extension have the same size and shape.

5. The dual port static random access memory cell of claim 1 , wherein:

the third pass transistor has a gate having a third extension to a third contact for contacting a second word line;

the fourth pass transistor has a gate having a fourth extension to a fourth contact for contacting the second word line; and

the third extension and the fourth extension have the same size and shape as the first extension and the second extension.

6. The dual port static random access memory cell of claim 1 , wherein:

the first pull-down transistor and the second pull-down transistor are located between the first pass transistor and the second pass transistor; and

the third pull-down transistor and the fourth pull-down transistor are located between the third pass transistor and the fourth pass transistor.

7. The dual port static random access memory cell of claim 2 wherein the third and fourth active regions have the same size and shape.

8. The dual port static random access memory cell of claim 7 , wherein the third active region comprises a first N well.

9. The dual port static random access memory cell of claim 8 , wherein the first active region comprises a first P well and the second active region comprises a second P well.

10. The dual port static random access memory cell of claim 3 , wherein the first data node further comprises a first polysilicon layer contacting the first metal layer and the second data node further comprises a second polysilicon layer contacting the second metal layer, wherein the first polysilicon layer and the second polysilicon layer have the same size and shape.

11. A method of making a dual port static random access memory cell, comprising:

forming a first active region having a first shape and size;

forming a second active region having the first shape and size;

forming a first pass transistor in the first active region contacting a first bit line contact and a first word line contact;

forming a second pass transistor in the first active region contacting a second bit line contact and a second word line contact, wherein:

the first word line contact and the second word line contact are for contacting a first word line,

the first bit line contact is for contacting a first bit line; and

the second bit line contact is for contacting a bit line complementary to the first bit line;

forming a first pull-down transistor and a second pull-down transistor in the first active region;

forming a third pass transistor in the second active region contacting a third bit line contact and a third word line contact;

forming a fourth pass transistor in the second active region contacting a fourth bit line contact and a fourth word line contact, wherein:

the third word line contact and the fourth word line contact are for contacting a second word line;

the third bit line contact is for contacting a second bit line; and

the fourth bit line contact is for contacting a bit line complementary to the second bit line;

forming a third pull-down transistor and a fourth pull-down transistor in the second active region;

coupling the first pull-down transistor in parallel with the third pull-down transistor;

coupling the second pull-down transistor in parallel with the fourth pull-down transistor; and

forming a first pull-up transistor and a second pull-up transistor between the first active region and the second active region.

12. The method of claim 11 , wherein the step of forming the first pull-up transistor and the second pull-up transistor comprises:

forming a third active region between the first and second active regions having a second shape and size;

forming a fourth active region between the first and second active regions having the second shape and size;

forming the first pull-up transistor in the third active region; and

forming the second pull-up transistor in the fourth active region.

13. The method of claim 11 , wherein the step of coupling the first pull-down transistor in parallel with the third pull-down transistor comprises forming a first metal layer having a third size and shape, wherein a first end of the first metal layer electrically contacts a first current electrode of the first pull-down transistor and a second end of the first metal layer electrically contacts a first current electrode of the third pull-down transistor.

14. The method of claim 11 , wherein step of coupling the second pull-down transistor in parallel with the fourth pull-down transistor comprises forming a second metal layer having the third size and shape, wherein a first end of the second metal layer electrically contacts a first current electrode of the second pull-down transistor and a second end of the second metal layer electrically contacts a first current electrode of the fourth pull-down transistor.

15. The method of claim 11 , wherein the step of forming the first active region comprises forming an isolation region in a semiconductor substrate to define a surrounding boundary of the first active region and doping the substrate within the surrounding boundary to p-type.

16. The method of claim 11 , wherein:

the steps of forming the first pull-down transistor and second pull-down transistor are further characterized as forming the first and second pull-down transistors between the first and second pass transistors.

17. The method of claim 13 , wherein the step of coupling the first pull-down transistor in parallel with the third pull-down transistor comprises coupling a second current electrode of the first pull-down transistor to ground and coupling a second current electrode of the third pull-down transistor to ground.

18. A dual port static random access memory cell, comprising:

a first active region having a first size and shape;

a first pass transistor having a first current electrode and second current electrode in the first active region;

a first pull-down transistor having a first current electrode and a second current electrode in the first active region, wherein the first current electrode of the first pull-down transistor is in common with the second current electrode of the first pass transistor;

a second pass transistor having a first current electrode and second current electrode in the first active region;

a second pull-down transistor having a first current electrode and a second current electrode in the first active region, wherein the first current electrode of the second pull-down transistor is in common with the second current electrode of the second pass transistor and the second current electrode of the second pull-down transistor is in common with the second current electrode of the first pull-down transistor;

a second active region having the first size and shape;

a third pass transistor having a first current electrode and second current electrode in the second active region;

a third pull-down transistor having a first current electrode and a second current electrode in the second active region, wherein the first current electrode of the third pull-down transistor is in common with the second current electrode of the third pass transistor;

a fourth pass transistor having a first current electrode and second current electrode in the second active region;

a fourth pull-down transistor having a first current electrode and a second current electrode in the second active region, wherein the first current electrode of the fourth pull-down transistor is in common with the second current electrode of the fourth pass transistor and the second current electrode of the fourth pull-down transistor is in common with the second current electrode of the third pull-down transistor; and

a first pull-up transistor and a second pull-up transistor located between the first active region and the second active region.

19. The dual port static random access memory cell of claim 18 , wherein:

the first current electrode of the first pull-down transistor is coupled to the first current electrode of the third pull-down transistor through a first metal layer having a second shape and size;

the first current electrode of the second pull-down transistor is coupled to the first current electrode of the fourth pull-down transistor through a second metal layer having the second shape and size;

the second current electrodes of the first, second, third, and fourth pull-down transistors are coupled to a ground terminal;

a first continuous conductive layer having a third size and shape is used as a gate for the first pull-down transistor and a gate for the third pull-down transistor;

a second continuous conductive layer having the third size and shape is used as a gate for the second pull-down transistor and a gate for the fourth pull-down transistor;

the first current electrode of the first pass transistor is coupled to a first bit line;

the first current electrode of the second pass transistor is coupled to a bit line complementary to the first bit line;

the first current electrode of the third pass transistor is coupled to a second bit line; and

the first current electrode of the fourth pass transistor is coupled to a bit line complementary to the second bit line.

Assignments (18)