Method and apparatus for performing metalization in an integrated circuit process
View Patent ↗A reverse fill pattern is used in an integrated circuit (IC) that comprises a metal layer having slots formed therein in the shape of rhombuses. The distribution of rhombic slots ensures that electrical current is evenly distributed in the conductor, even at the edge regions of the conductor. This even distribution of rhombic slots ensures that electrical current is evenly distributed at least in the central region, and in most if not all cases, across the entire region of the conductor including the edge regions. Thus, the reverse fill pattern prevents current crowding. By preventing current crowding, more stringent metal distribution targets can be met without creating or exacerbating problems associated with IR drop and EM, and without having to add any extra metal to avoid such problems.
1. An apparatus for designing a rhombic reverse fill pattern for a metal element of an integrated circuit (IC), the apparatus comprising:
a memory device; and
a processor, the processor being configured to perform a design algorithm of a rhombic reverse fill pattern design, the design algorithm generating a reverse fill pattern design for one or more metal elements of the IC that meets a target metal density, the reverse fill pattern design including a metal having slots formed therein, each slot being substantially rhombic in shape.
2. The apparatus of claim 1 , wherein each slot has a size, Y, where Y is a positive value, and wherein adjacent slots are separated by a spacing distance, 2X, where X is a positive value, the values for Y and 2X being selected to ensure that the metal layer comprising the rhombic reverse fill pattern meets the target metal density.
3. The apparatus of claim 2 , wherein the target metal density, Z, is related to X and Y as (Y) 2 /(2X+Y) 2 =1−Z/100, where Z is the target metal density stated in terms of a percentage.
4. The apparatus of claim 1 , wherein each rhombic slot has a first side and a second side that are substantially parallel to each other and at substantially 45° angles relative to a side of the metal element, the side of the element being substantially parallel to a direction of current flow through the metal element.
5. The apparatus of claim 4 , wherein said each rhombic slot has a third side and a fourth side that are substantially parallel to each other and substantially perpendicular to the first and second sides of said each rhombic slot, the third and fourth sides being at substantially 45° angles relative to the side of the metal element.
6. A metallization apparatus for forming a rhombic reverse fill pattern in a metal element of an integrated circuit (IC), the apparatus comprising:
a memory device;
a processor, the processor being configured to perform a metallization algorithm of a rhombic reverse fill pattern, the metallization algorithm generating control signals for controlling a metallization process;
a metallization machine, the metallization machine receiving the control signals generated by the processor and performing a metallization process that forms a reverse fill pattern in one or more metal layers of the IC, the reverse fill pattern including a layer of metal having slots formed therein, each slot being substantially rhombic in shape, and wherein the reverse fill pattern meets a target metal density.
7. The apparatus of claim 6 , wherein each slot has a size, Y, where Y, is a positive value, and wherein adjacent slots are separated by a spacing distance, 2X, where X is a positive value, the values for Y and 2X being selected prior to the rhombic reverse fill pattern being formed in a metal layer to ensure that a metal layer comprising the rhombic reverse fill pattern forming a metal element that meets the target metal density.
8. The apparatus of claim 7 , wherein the target metal density is related to X and Y as (Y) 2 /(2X+Y) 2 =1−Z/100, where Z is the target metal density stated in terms of a percentage.
9. The apparatus of claim 6 , wherein each rhombic slot has a first side and a second side that are substantially parallel to each other and at substantially 45° angles relative to a side of the metal element, the side of the metal element being substantially parallel to a direction of current flow through the metal element.
10. The apparatus of claim 9 , wherein each rhombic slot has a third side and a fourth side that are substantially parallel to each other and perpendicular to the first and second sides of said each rhombic slot, the third and fourth sides being at 45° angles relative to the side of the metal element.
11. A automated method for designing a rhombic reverse fill pattern for a metal layer of an integrated circuit (IC), the automated method comprising:
with at least one of software and hardware, selecting a size value and a spacing distance value for rhombic slots of a rhombic reverse fill pattern to meet a target metal density; and
with a computer aided design tool, generating a rhombic reverse fill pattern design for a metal element of the IC using the selected size and spacing distance values, the reverse fill pattern design including a layer of metal having the rhombic slots formed therein, each rhombic slot being substantially rhombic in shape and having a size corresponding substantially to the selected size value, and wherein adjacent rhombic slots are separated by substantially the selected spacing distance.
12. The automated method of claim 11 , wherein the target metal density is related to the size and spacing distance values as (Y) 2 /(2X+Y) 2 =1−Z/100, where Y is the size value, 2X is the spacing distance value and Z is the target metal density stated in terms of a percentage.
13. The automated method of claim 11 , wherein each rhombic slot has a first side and a second side that are substantially parallel to each other and at 45° angles relative to a side of the metal element, the side of the metal element being substantially parallel to a direction of current flow through metal the element.
14. The automated method of claim 13 , wherein each rhombic slot has a third side and a fourth side that are substantially parallel to each other and substantially perpendicular to the first and second sides of said each rhombic slot, the third and fourth sides being at substantially 45° angles relative to the side of the metal element.
15. A automated method for forming a rhombic reverse fill pattern in a metal layer of an integrated circuit (IC), the automated method comprising:
receiving a rhombic reverse fill pattern design that meets a target metal density with one of a mask pattern creation system and a metallization system; and
forming a rhombic reverse fill pattern in a metal layer of the IC having the rhombic reverse fill pattern design with a metallization system, the rhombic reverse fill pattern including a layer of metal having slots formed therein, each slot being substantially rhombic in shape, the metal layer having the substantially rhombic slots formed therein comprising a metal element of the IC.
16. The automated method of claim 15 , wherein each slot has a particular size, Y, where Y is a positive value, and wherein adjacent slots are separated by a particular spacing distance, 2X, where X is a positive value, the values for Y and 2X being indicated in the received design.
17. The automated method of claim 16 , wherein the target metal density is related to X and Y as (Y) 2 /(2X+Y) 2 =1−Z/100, where Z is the target metal density stated in terms of a percentage.
18. The automated method of claim 15 , wherein each rhombic slot has a first side and a second side that are parallel to each other and at 45° angles relative to a side of the metal element, the side of the metal element being parallel to a direction of current flow through the metal element.
19. The automated method of claim 18 , wherein each rhombic slot has a third side and a fourth side that are parallel to each other and perpendicular to the first and second sides of said each rhombic slot, the third and fourth sides being at 45° angles relative to the side of the metal element.
20. A computer program for generating a rhombic reverse fill pattern design for a metal element of an integrated circuit, the rhombic reverse fill pattern design including a layer of metal having slots formed therein, the computer program comprising instructions for execution by a processor, the instructions being stored on a computer-readable medium, the computer program comprising:
instructions for receiving input that describes an integrated circuit design;
instructions for receiving user input including a size value corresponding to a size of each slot and a spacing distance value corresponding to a spacing distance between adjacent slots, wherein each slot is substantially rhombic in shape; and
instructions for generating a substantially rhombic reverse fill pattern design based on the received user input.
21. A computer program for controlling a metallization process to form a rhombic reverse fill pattern in one or more metal layers of an integrated circuit, the rhombic reverse fill pattern comprising a layer of metal having slots formed therein, the computer program comprising instructions for execution by a processor, the instructions being stored on a computer-readable medium, the computer program comprising:
instructions for receiving a rhombic reverse fill pattern design, the rhombic reverse fill pattern design including a size value corresponding to the size of each slot and a spacing distance value corresponding to a spacing distance between adjacent slots, wherein each slot is substantially rhombic in shape; and
instructions for generating control signals for controlling a metallization machine to cause the metallization machine to form a substantially rhombic reverse fill pattern having the received rhombic reverse fill pattern design in one or more metal layers of the integrated circuit.
22. An integrated circuit (IC) device having at least one metal element that has a substantially rhombic reverse fill pattern, the substantially rhombic reverse fill pattern including a layer of metal having slots formed therein, each slot being substantially rhombic in shape.
23. An integrated circuit (IC) device having at least one metal element that has a substantially rhombic reverse fill pattern, the substantially rhombic reverse fill pattern including a layer of metal having slots formed therein, each slot being substantially rhombic in shape, and wherein the substantially rhombic reverse fill pattern meets a target metal density.
24. An integrated circuit (IC) device having at least one metal element that has a substantially rhombic reverse fill pattern, the substantially rhombic reverse fill pattern including a layer of metal having slots formed therein, each slot being substantially rhombic in shape, and wherein the substantially rhombic reverse fill pattern meets a target metal density without increasing electromigration (EM) in the metal element.
25. An integrated circuit (IC) device having at least one metal element that has a substantially rhombic reverse fill pattern, the substantially rhombic reverse fill pattern including a layer of metal having slots formed therein, each slot being substantially rhombic in shape, and wherein the substantially rhombic reverse fill pattern meets a target metal density without increasing IR drop.