Edit Structure for Logic Gate Input Mask Modification
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Solution Overview
Problem
Existing tie-in circuits in sub-micron logic circuits require modifying multiple masks to change the logic state of a logic gate, making the process expensive and time-consuming, as each tie-in circuit is associated with specific metal layers, necessitating changes to associated masks even if only one modification is needed.
Innovation Solution
The edit structure allows the input of a logic gate to be modified by changing any one of the metal or via masks used to form the metal interconnect structure, enabling the logic state to be changed without altering masks associated with other metal layers, thereby reducing the number of masks that need to be modified.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the tie-in circuit is implemented with specific metal layers, then the logic gate input can be permanently connected to power supply or ground, but modifying the logic state requires changing multiple masks which increases cost and time
Solution Approach 1:
The patent divides the tie-in circuit into separate functional components: a polysilicon resistor structure for the permanent connection and metal interconnect layers for signal routing. This segmentation allows the resistor to be formed once while enabling flexible modification of the metal layer connections through single-mask changes, resolving the contradiction between reliable permanent connection and ease of modification.
Solution Approach 2:
The polysilicon resistor structure acts as an intermediary element between the logic gate input and the power supply/ground lines. This intermediary allows the permanent connection function to be decoupled from the metal interconnect structure, enabling modification of logic states by changing only metal layer masks without affecting the underlying resistor structure.
2Adaptability or versatility
If multiple masks are modified to change logic state, then the tie-in circuit can be reconfigured, but the process becomes expensive and time-consuming
Solution Approach 1:
The polysilicon resistor structure is formed in advance during the standard fabrication process, establishing the permanent connection framework before metal interconnect layers are added. This preliminary action enables subsequent logic state changes to be achieved by modifying only the metal layer masks, rather than requiring multiple mask changes across different fabrication stages.
3Ease of operation
If the input is directly connected to power supply or ground line, then the logic gate input is permanently connected, but voltage and current spikes can permanently damage the logic gate
Solution Approach 1:
The polysilicon resistor structure serves as a protective intermediary between the logic gate input and the power supply/ground lines. This resistor limits current flow and attenuates voltage and current spikes from reaching the logic gate, while still maintaining the permanent connection function. The metal interconnect layers then provide the routing flexibility without direct exposure to harmful electrical transients.
Data Source
AI summary
An edit structure is disclosed that allows the input of a logic gate to be changed by modifying any one of the metal and via masks that are used to form the metal interconnect structure. As a result, a first permanent logic state provided by a tie-in circuit can be changed to a second permanent logic state by modifying any one of the metal and via masks that are used to form the metal interconnect structure.