Method of adjusting signal to noise ratio of SRAM and invertor structure

A method of adjusting a signal-to-noise ratio (SNR) of a static random access memory (SRAM), comprising:

• providing a substrate, a first long fin structure and a second long fin structure disposed on the substrate, a first short fin structure and a second short fin structure disposed on the substrate and between the first long fin structure and the second long fin structure, a first gate line crossing the first long fin structure, the first short fin structure, and the second long fin structure, and a second gate line crossing the first long fin structure, the second short fin structure and the second long fin structure, wherein the first long fin structure comprises a first side and a second side, the second side faces the first short fin structure, the first side is opposite to the second side, the second long fin structure comprises a third side and a fourth side, the fourth side faces the second short fin structure, and the third side is opposite to the fourth side;
• and
• performing a gate line cutting step, comprising:
• removing the second gate line between the first long fin structure and the second short fin structure by a first length;
• removing the first gate line between the second long fin structure and the first short fin structure by the first length;
• removing the first gate line at the first side of the first long fin structure by a second length;
• and
• removing the second gate line at the third side of the second long fin structure by the second length;
• wherein an SNR of an SRAM having the first length greater than the second length is greater than an SNR of an SRAM having the first length equal to the second length.