Universal Spare Logic Gate Configured via Single Mask Layer
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Solution Overview
Problem
Conventional semiconductor integrated circuit manufacturing lacks a reliable method to modify logic circuit designs without requiring extensive changes to photolithographic masks, as spare logic gates often do not provide the necessary functionality and modifying masks is costly.
Innovation Solution
A universal two-input spare logic gate is designed using a 4-to-1 multiplexer circuit, where select inputs are used as logic gate inputs and the output is configured to perform any desired logic function by modifying a single photolithographic mask, allowing the gate to be connected to a target circuit with minimal mask changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional spare logic gates are used for circuit design modifications, then the gates are available for insertion, but they do not provide the particular logic functionality required
Solution Approach 1:
The patent implements a universal spare logic gate using a 4-to-1 multiplexer that can be configured to perform any of the 16 possible two-input logic functions (AND, OR, NAND, NOR, XOR, XNOR, and their inverted versions) by selectively connecting data inputs to logic high or logic low. This single gate structure replaces the need for multiple specialized spare gates, providing both versatility and reliability in matching required logic functionality.
2Ease of operation
If photolithographic masks are modified to insert a spare logic gate, then the gate can be connected to the target circuit, but the operation becomes relatively expensive
Solution Approach 1:
The patent designs the universal spare logic gate with all necessary interconnection structures预先 built into the circuit layout, including metal traces and vias that can be selectively activated. By preparing the gate structure in advance with all possible connection paths already present in the layout, the patent enables configuration through simple mask adjustments rather than requiring complex mask redesigns, significantly reducing manufacturing costs.
Solution Approach 2:
The universal spare logic gate is designed with segmented, modular interconnection structures where different metal layers and via layers can be independently configured. This segmentation allows selective activation of specific connection paths through mask adjustments, enabling flexible gate insertion and configuration without requiring comprehensive mask modifications across the entire circuit.
3Adaptability or versatility
If multiple photolithographic masks are modified to configure and connect a spare logic gate, then the desired logic function can be achieved, but the process becomes complex and costly
Solution Approach 1:
The patent combines the configuration and connection functions into a single mask layer modification process. By integrating the logic gate configuration (selecting which data inputs are active) and the circuit connection (routing signals to and from the gate) into one unified mask structure, the patent simultaneously achieves both goals with a single mask change, reducing complexity while maintaining full logic function configurability.
Data Source
AI summary
A spare logic circuit for implementing any one of a plurality of logic gates includes a multiplexer circuit whose select inputs are utilized as logic gate inputs, and whose output is utilized as a logic gate output. Each of a plurality of data inputs of the multiplexer circuit is configured to receive one of first and second logic voltage levels which define the desired logic function. By modifying a single photolithographic mask, the spare logic gate can be: configured to perform the desired logic function; connected into a target logic circuit; or both configured and connected into a target logic circuit.