Impedance Calibration Test Standards for Probe Systems
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Solution Overview
Problem
Current impedance calibration methods for probe systems are inadequate for accurately testing smaller semiconductor devices and integrated circuits, requiring improved test standards and methodologies to achieve higher precision and accuracy.
Innovation Solution
The introduction of test standards that include a plurality of test structures, such as thin film thru and offset test structures, which are designed to simultaneously contact multiple probe regions of a probe head, applying predetermined test conditions to each region, and methods for aligning the probe head with these standards to ensure accurate calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional calibration methods are used, then the calibration process is simple, but the measurement precision and accuracy decrease for smaller semiconductor devices
Solution Approach 1:
The test standard is segmented into multiple separate test structures (thru test structure, offset test structure, short test structure, open test structure) instead of using a single integrated calibration standard. Each test structure is positioned to contact a specific probe region, allowing independent calibration of each probe tip. This segmentation enables precise impedance calibration for each probe region while maintaining manageable complexity through modular design.
Solution Approach 2:
Each test structure is designed with specific local characteristics tailored to its function: the thru test structure provides a direct transmission path, the offset test structure provides a known impedance transformation, the short test structure provides a zero-impedance reference, and the open test structure provides an infinite-impedance reference. This local quality differentiation allows each probe region to be calibrated with the appropriate reference condition, improving overall measurement precision.
2Measurement precision
If multiple test structures are used to contact multiple probe regions, then the impedance calibration accuracy improves, but the alignment and positioning complexity increases
Solution Approach 1:
The test structures are pre-positioned on the test standard substrate at specific locations that correspond to the probe regions. The alignment marks are also pre-positioned to indicate the correct placement of the test standard relative to the probe head. This preliminary action of pre-positioning eliminates the need for complex real-time alignment adjustments during operation, as the operator only needs to place the test standard on the substrate and use the alignment marks to ensure proper orientation.
3Productivity
If the test standard includes multiple test structures for simultaneous contact, then the calibration efficiency improves, but the manufacturing complexity increases
Solution Approach 1:
The test standard substrate serves multiple functions: it supports multiple test structures, provides alignment marks for positioning, and acts as a stable mounting platform. The test structures themselves are designed to work with standard probe heads and can be used for various calibration operations (impedance calibration, gain calibration, phase calibration). This multi-functionality reduces the need for multiple separate calibration standards, simplifying the overall manufacturing process while maintaining high calibration throughput.
Data Source
AI summary
Test standards and methods for impedance calibration of a probe system and probe systems that include the test standards and/or utilize the methods are disclosed herein. The test standards include at least one test structure. In some embodiments, the test standard further includes an alignment structure that is associated with the test structure. In some embodiments, the test standards include a plurality of test structures. In some embodiments, the plurality of test structures includes a thin film thru test structure and a thin film offset test structure. In some embodiments, the plurality of test structures is positioned to simultaneously contact a plurality of probe regions of a probe head. The methods include methods of calibrating a probe system.