CMOS Sensor Redundancy for Metal Short Isolation
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Solution Overview
Problem
CMOS sensor arrays face significant yield losses due to metal interconnect shorts, particularly in larger devices, leading to dead columns and rows, which are not effectively addressed by existing technologies.
Innovation Solution
Incorporating in-cell redundancy and external control mechanisms to selectively activate redundant elements, allowing for field-repair and addressing various fault types, including metal-to-metal and poly shorts, by using cell-wise redundant output stages and control facilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the sensor array size is increased to reduce pixel size, then the number of column defects increases due to metal interconnect shorts, but this leads to severe yield losses and dead columns/rows
Solution Approach 1:
The patent implements preliminary action by pre-configuring redundant column circuits and control logic before manufacturing defects occur. The redundant columns are prepared in advance and can be rapidly activated through control signals to replace defective columns, preventing yield loss without requiring physical repair interventions.
Solution Approach 2:
The patent changes the operational parameter of the sensor array by dynamically reconfiguring which columns are active through control logic. When a defect is detected, the system changes the state of column selection to activate redundant columns, effectively transforming the array's operational parameters to maintain functionality despite physical defects.
2Object-affected harmful factors
If metal interconnect distance is increased to reduce shorts, then the pixel size must be reduced, but this increases the number of columns and potential defect points
Solution Approach 1:
The patent applies copying by creating redundant copies of column circuits that can replace defective ones. Instead of modifying the physical metal interconnect structure, the system creates functional copies of the column logic that can be activated to substitute for columns affected by metal shorts, thereby addressing the harmful factor without changing pixel dimensions.
3Reliability
If redundancy is implemented within the cell by doubling parts, then robustness against defects improves, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the sensor array into independently controllable column segments with associated redundant logic. Rather than duplicating entire pixel cells, the system segments the column structure and implements redundancy at the column level with control facilities that can selectively activate redundant segments, reducing overall complexity compared to full cell-level redundancy.
4Ease of repair
If field-repair capability is added to remediate faults, then the sensor array becomes permanently repairable, but the control mechanism complexity increases
Solution Approach 1:
The patent implements self-service by incorporating control logic directly within the sensor array that enables automatic detection and activation of redundant columns without external intervention. The control facility monitors column health and autonomously switches to redundant columns when defects are detected, providing field-repair capability while minimizing the complexity of external control mechanisms.
Data Source
AI summary
A CMOS-based sensor apparatus comprises an array of sensor cells that are interconnected by a first set of vertical driver lines to a selective driver facility and by a second set of horizontal sensing lines to a sensing facility for sensing respectively sensed amounts of radiation.In particular, the sensor cells through being appropriately spaced in at least either row or column direction, comprise a redundancy facility that is selectively activatable for isolating an interconnect short on the basis of externally applied control actuation.