Mask Fingerprinting via SRAM Bit Correlation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The challenge in semiconductor device security lies in verifying that microprocessors and other semiconductor devices have been fabricated according to design data without alteration, especially when design data is sent to a third party for fabrication, as traditional visual wafer inspection is not feasible due to cost and time-intensive expenses.
Innovation Solution
A method involving measuring the initial state of SRAM bits on a wafer, identifying signature SRAM bits with consistent initial states, and physically measuring their dimensions to create a mask fingerprint, which can be used to verify if additional chips were manufactured using the same original design mask without alteration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If visual wafer inspection is performed on every wafer, then manufacturing quality verification is improved, but cost and time consumption increase significantly
Solution Approach 1:
The patent creates a digital copy or fingerprint of the mask design data and compares it against the actual manufactured wafer. Instead of performing full visual inspection, a representative fingerprint is extracted and matched, significantly reducing inspection time while maintaining verification reliability.
Solution Approach 2:
The patent extracts key distinctive features or fingerprints from the mask design data and wafer images. By taking out only the essential identifying characteristics rather than analyzing the entire wafer, the inspection process becomes much faster while still ensuring quality verification.
2Reliability
If visual wafer inspection is performed on every wafer, then manufacturing quality verification is improved, but equipment cost increases
Solution Approach 1:
The patent uses digital fingerprinting and data comparison methods that can be implemented with standard equipment, avoiding the need for expensive specialized visual inspection equipment. The approach relies on processing digital representations rather than requiring complex optical inspection systems.
Solution Approach 2:
The patent replaces the mechanical/optical visual inspection system with a digital data processing and comparison system. By substituting physical inspection mechanisms with computational methods, equipment costs are reduced while maintaining verification capability.
3Adaptability or versatility
If mask data is sent to third party for fabrication, then manufacturing capability is improved, but security risk increases
Solution Approach 1:
The patent implements a feedback mechanism where the fingerprint extracted from the manufactured wafer is compared against the original mask design data. This closed-loop verification provides confidence that the third party fabrication process has not altered the design, mitigating security risks while enabling external manufacturing.
Solution Approach 2:
The patent performs preliminary fingerprint extraction and verification steps during the fabrication process or immediately afterward. By establishing verification protocols in advance and performing checks at critical stages, the system prevents undetected alterations before they can cause security issues.
Data Source
AI summary
According to a first aspect of the present invention, there is provided a method, a computer system and a computer program product. The method, computer system and computer program product including measuring an initial state of a set of SRAM bits on the wafer, identifying a first set of signature SRAM bits on the wafer, of the set of SRAM bits on the wafer, where the first set of SRAM bits comprise a consistent initial state greater than a first threshold percentage of times, measuring physically dimensions of features of the first set of SRAM bits on the wafer; and identifying a set of signature SRAM bits of the first set of SRAM bits on the wafer, wherein the set of signature SRAM bits comprise physical dimensions of features which correlate to the initial state of each correlated SRAM bit.