Parallel Test Structure for Defect DUT Detection via Resistance Measurement
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Solution Overview
Problem
Current test structures for integrated circuits require sequential testing of multiple devices under test (DUTs), which is time-consuming and inefficient, and are limited in detecting various defect states beyond open contacts, such as shorts, which can be destructive and pose safety risks.
Innovation Solution
A test structure where DUTs are connected in parallel to test contact pads via conducting lines with series test resistors of known resistances, allowing for a single measurement to indicate the number of DUTs in a defect state, thereby simplifying the detection of defects like shorts and improving process window determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sequential testing of multiple DUTs is performed using individual test contact pads, then each device can be tested separately, but the testing time increases and substrate area consumption increases
Solution Approach 1:
Multiple DUTs are connected in parallel between a common first test contact pad and a common second test contact pad, allowing simultaneous testing of multiple devices through a single measurement configuration. This merging approach enables parallel testing without requiring individual test contact pads for each DUT, thereby reducing both testing time and substrate area consumption while maintaining defect detection capability.
Solution Approach 2:
The common test contact pads serve multiple functions by being shared across all DUTs in the parallel configuration. The first test contact pad and second test contact pad collectively test multiple devices, making the testing system universal rather than device-specific. This multi-functionality reduces the number of required test contact pads and enables efficient batch testing.
2Measurement precision
If sequential testing of multiple DUTs is performed using individual test contact pads, then each device can be tested separately, but the substrate area consumption increases
Solution Approach 1:
Multiple DUTs share common test contact pads through parallel connection, merging the testing function into a compact configuration. This reduces the substrate area required compared to having individual test contact pads for each DUT, as the common pads are positioned at the ends of parallel conducting lines rather than requiring separate pad areas for each device.
Solution Approach 2:
The test structure utilizes spatial arrangement by connecting DUTs in parallel between common contact pads, effectively organizing devices along conducting lines rather than requiring discrete two-dimensional pad placement for each device. This dimensional reorganization optimizes substrate area utilization.
3Measurement precision
If complex control circuitry is used for precise movement of probe contact needles, then sequential testing can be performed, but the device complexity increases
Solution Approach 1:
The invention extracts and eliminates the complex control circuitry requirement by changing the test structure configuration. Instead of moving probe contact needles with precision control systems, the solution uses fixed common test contact pads with DUTs connected in parallel, removing the need for complex movement control while maintaining measurement capability through the parallel connection architecture.
4Measurement precision
If traditional test structures are used for detecting open contacts, then via defects can be identified, but other defect states like shorts cannot be detected
Solution Approach 1:
The parallel connection configuration with common test contact pads creates a universal testing structure that can detect multiple defect states including open contacts, shorts, and resistance variations. By measuring the equivalent resistance of the parallel network, the system can identify different defect conditions in DUTs, making the test structure versatile rather than limited to single defect type detection.
Solution Approach 2:
The invention utilizes changes in electrical resistance parameters to detect different defect states. By measuring the equivalent resistance of the parallel-connected DUTs and comparing it against expected values, the system can identify opens (infinite resistance), shorts (zero or near-zero resistance), and partial defects (intermediate resistance values), enabling broad defect detection through parameter analysis.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables fast and simple detection of defect DUTs, reducing testing time and substrate area consumption, and providing a broader application range beyond just identifying open contacts, including the detection of electrical shorts that can cause malfunctions and safety hazards.
Implementation Method 1
respective first test resistors are connected in series between the respective DUTs and either the first or second conducting line, the first test resistors having known respective electrical test resistances, such that a total electrical resistance between the first an second test contact pads is indicative of the number of DUTs, which have the second electrical device resistance
Data Source
AI summary
The present invention relates to a test structure that comprises at least two devices under test DUT, which respectively have a first electrical device resistance in a non-defect state and a second electrical device resistance in defect state, the first being higher than the second electrical device resistance. In the test structure the DUTs are connected in parallel to a first test contact pad via a first conducting line and connected in parallel to a second test contact pad via a second conducting line, and respectively connected to the first conducting line via respective first test resistors, which have known respective electrical test resistances, such that a total electrical resistance between the first an second test contact pads is indicative of the number of DUTs, which have the second electrical device resistance. The test structure allows testing a larger number of DUTs in parallel in a single measurement.