Dynamic Scan Port Allocation for Test Resource Optimization
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Solution Overview
Problem
Current semiconductor device testing methods face challenges in efficiently utilizing test resources and reducing test time and cost, particularly due to differences in controllability and observability requirements between scan-in and scan-out operations, and insufficient drive strength of output ports, which can lead to suboptimal test cycles and resource utilization.
Innovation Solution
The method involves dynamically selecting input and output ports and scan channels based on control signals to perform scan-in and scan-out operations, allowing for flexible allocation of resources and internal comparison of scan outputs to overcome drive strength limitations, thereby optimizing test efficiency and reducing redundant operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If scan-in and scan-out operations use the same I/O ports for both operations, then the test structure is simple, but the drive strength of output ports is insufficient to drive the tester load, impairing shift speed and test time
Solution Approach 1:
The patent divides the I/O ports into two distinct sets: a first set of I/O ports dedicated to scan-in operations and a second set of I/O ports dedicated to scan-out operations. This segmentation allows each port type to be optimized for its specific function, with input ports receiving test patterns from the tester and output ports providing scan results back to the tester, thereby resolving the drive strength limitation while maintaining structural clarity
Solution Approach 2:
The patent implements a flexible port allocation mechanism where the first and second sets of I/O ports can be dynamically assigned to different scan channels based on test requirements. This multi-functional design allows the same physical ports to serve different purposes in different test scenarios, optimizing both drive strength utilization and test efficiency
2Productivity
If all I/O ports are used for scan operations, then resource utilization is maximized, but the difference between desired controllability and observability leads to suboptimal test cycles and wasted resources
Solution Approach 1:
The patent introduces dynamic control signals that enable flexible allocation of I/O ports to scan channels based on the specific test pattern requirements. The controller can adaptively assign ports to either scan-in, scan-out, or both operations depending on the controllability and observability needs of each scan channel, optimizing resource utilization while avoiding redundant operations that would waste test time
Solution Approach 2:
The patent applies different operational modes to different I/O ports based on local test requirements. Some ports are configured for scan-in only, others for scan-out only, and others for both operations, depending on the specific needs of the scan channels they serve. This localized optimization ensures that each port contributes maximally to the overall test efficiency
Data Source
AI summary
A method of testing devices under test (DUTs) and testing system are disclosed. The method comprises generating at least one control signal associated with a test pattern structure received from a testing system. The method further comprises selecting M1 number of ports from M number of I/O ports in the DUT to receive scan input corresponding to the test pattern structure based on the control signal, selecting M2 number of ports from the M number of I/O ports to provide scan output based on the control signal, wherein each of M1 and M2 is a number selected from 0 to M, and wherein a sum of M1 and M2 is less than or equal to M. Thereafter, the method comprises performing a scan testing of the DUT based on the scan input provided to the M1 number of ports and receiving the scan output from the M2 number of ports.