Interconnect Structure for Improving Memory Performance and/or Logic Performance

Abstract

Configurations of metal layers of interconnect structures, and methods of fabrication thereof, are disclosed for memories, such as a static random-access memory (SRAM). For example, bit lines are placed in a metal one (M1) layer, which is a lowest metallization level of an interconnect structure of a memory cell, to minimize bit line capacitance, and configure bit lines as the widest metal lines of the metal one layer to minimize bit line resistance. In some embodiments, the interconnect structure has a double word line structure to reduce word line resistance. In some embodiments, the interconnect structure has a double voltage line structure to reduce voltage line resistance. In some embodiments, jogs are added to a word line and/or a voltage line to reduce its respective resistance. In some embodiments, via shapes of the interconnect structure are configured to reduce resistance of the interconnect structure.

What is claimed is: 
     
         1 . A method comprising:
 forming a memory cell; and   forming an interconnect structure over and connected to the memory cell, wherein the forming the interconnect structure includes:
 forming a bottommost metal layer of the interconnect structure, wherein the bottommost metal layer has metal lines connected to the memory cell, wherein the metal lines include a bit line, a first voltage line for receiving a first voltage, a voltage line landing pad, and a word line landing pad, wherein a width of the bit line is a widest width of the metal lines, 
 forming a bit line bar, a word line, and a second voltage line for receiving a second voltage that is different than the first voltage, wherein the second voltage line is connected to the voltage line landing pad and the word line is connected to the word line landing pad, 
 wherein the bit line, the bit line bar, the first voltage line, and the second voltage line extend along a first lengthwise direction, and 
 wherein the word line extends along a second lengthwise direction that is different than the first lengthwise direction. 
   
     
     
         2 . The method of  claim 1 , wherein the width of the bit line is a first width, the first voltage line has a second width, and a ratio of the first width to the second width is about 1.1 to about 2. 
     
     
         3 . The method of  claim 1 , wherein the width of the bit line is a first width, the voltage line landing pad has a second width, and a ratio of the first width to the second width is about 1.1 to about 2. 
     
     
         4 . The method of  claim 1 , wherein the width of the bit line is a first width, the word line landing pad has a second width, and a ratio of the first width to the second width is about 1.1 to about 2. 
     
     
         5 . The method of  claim 1 , wherein the width of the bit line is a first width, the metal lines further include the bit line bar, the bit line bar has a second width, and the second width is the same as the first width. 
     
     
         6 . The method of  claim 1 , wherein the first voltage line has a first portion having a first width and a second portion having a second width that is greater than the first width, wherein the second portion having the second width is an interconnection region of the first voltage line. 
     
     
         7 . The method of  claim 1 , wherein the bottommost metal layer is a first metal layer, the metal lines are first metal lines, and the forming the interconnect structure further includes:
 forming a second metal layer over the first metal layer, wherein the second metal layer has second metal lines that include the word line; and   forming a third metal layer over the second metal layer, wherein the third metal layer has third metal lines that include the second voltage line.   
     
     
         8 . The method of  claim 7 , wherein the word line is a first word line, the word line landing pad is a first word line landing pad, the third metal lines of the third metal layer further include a second word line landing pad connected to the first word line, and the forming the interconnect structure further includes:
 forming a fourth metal layer over the third metal layer, wherein the fourth metal layer has fourth metal lines that include a second word line, wherein the second word line is connected to the second word line landing pad.   
     
     
         9 . The method of  claim 7 , wherein the memory cell further includes a third voltage line for receiving the second voltage and the forming the interconnect structure further includes:
 forming a fourth metal layer over the third metal layer, wherein the fourth metal layer has fourth metal lines that include the third voltage line and the third voltage line is connected to the second voltage line.   
     
     
         10 . The method of  claim 1 , further comprising:
 forming a logic cell connected to a third voltage line for receiving a third voltage; and   wherein the interconnect structure includes the third voltage line extending along the first lengthwise direction, the metal lines of the bottommost metal layer include the third voltage line, and a first thickness of the bit line is the same as a second thickness of the third voltage line.   
     
     
         11 . A method comprising:
 forming a memory cell; and   forming an interconnect structure electrically coupled to the memory cell, wherein the forming the interconnect structure includes:
 forming a first metal layer electrically coupled to the memory cell, wherein the first metal layer includes a bit line, a first voltage line configured to receive a first voltage, a first voltage line landing pad, and a first word line landing pad, 
 forming a second metal layer over the first metal layer, wherein the second metal layer includes a first word line electrically coupled to the first word line landing pad and a second voltage line landing pad electrically coupled to the first voltage line landing pad, 
 forming a third metal layer over the second metal layer, wherein the third metal layer includes a second voltage line electrically coupled to the second voltage line landing pad and the second voltage line is configured to receive a second voltage, 
 forming a fourth metal layer over the third metal layer, wherein the fourth metal layer includes a second word line, and 
 wherein the bit line, the first voltage line, and the second voltage line extend along a first lengthwise direction, the first word line and the second word line extend along a second lengthwise direction that is different than the first lengthwise direction, and a first width of the bit line is greater than a second width of the first voltage line. 
   
     
     
         12 . The method of  claim 11 , wherein the first width of the bit line is greater than a third width of the first voltage line landing pad and a fourth width of the first word line landing pad. 
     
     
         13 . The method of  claim 11 , wherein the first metal layer further includes a bit line bar that extends along the first lengthwise direction, wherein a third width of the bit line bar is greater than the second width of the first voltage line. 
     
     
         14 . The method of  claim 13 , wherein the third width of the bit line bar is the same as the first width of the bit line. 
     
     
         15 . The method of  claim 11 , wherein the second word line is electrically coupled to the first word line. 
     
     
         16 . The method of  claim 15 , further comprising forming an edge cell, wherein the second word line is electrically coupled to the first word line by a first connection in the memory cell and a second connection in the edge cell. 
     
     
         17 . The method of  claim 11 , wherein the fourth metal layer further includes a third voltage line configured to receive the second voltage. 
     
     
         18 . The method of  claim 17 , wherein the third voltage line is electrically coupled to the second voltage line. 
     
     
         19 . A multilayer interconnect structure of a memory comprising:
 a first metallization layer that includes a bit line, a bit line bar, and a first voltage line configured to receive a first voltage, wherein the bit line, the bit line bar, and the first voltage line extend along a first routing direction, the first metallization layer is a bottommost metallization layer of the multilayer interconnect structure, and a bit line width of the bit line has a widest width of metal lines of the first metallization layer;   a second metallization layer disposed over the first metallization layer, wherein the second metallization layer includes a first word line that extends along a second routing direction that is different than the first routing direction;   a third metallization layer disposed over the second metallization layer, wherein the third metallization layer includes a second voltage line and a third voltage line configured to receive a second voltage that is different than the first voltage and the second voltage line and the third voltage line extend along the first routing direction; and   a fourth metallization layer disposed over the third metallization layer, wherein the fourth metallization layer includes a second word line that extends along the second routing direction.   
     
     
         20 . The multilayer interconnect structure of the memory of  claim 19 , wherein a ratio of the bit line width to a width of any one of the metal lines of the first metallization layer is about 1.1 to about 2.