Test Structure Activated by Probe Needle for IC Trimming
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Solution Overview
Problem
Existing integrated circuit testing methods face challenges in accessing internal signals for debugging and trimming, especially after packaging, as the packaging process can alter results and make temperature testing difficult due to the need for an open window, and changes made with focused ion beams are not easily reversible.
Innovation Solution
Incorporating test structures with CMOS transmission gates that can be activated by a probe needle to switch between open and closed states, allowing for reversible trimming and evaluation of internal signals without requiring the packaging window to remain open, using normally-open and normally-closed switching circuits and measure structures that retain their state even after the probe needle is removed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a probe needle must remain in contact with a probe pad on the die during final testing, then internal signals can be accessed for testing and trimming, but the packaging window must remain open making temperature testing difficult
Solution Approach 1:
The patent applies preliminary action by pre-configuring test structures with switchable connections during the packaging process. The switches are set to specific states (open or closed) before final testing, allowing temperature testing to proceed with the window closed while still enabling access to internal signals when needed. This preparatory configuration eliminates the need to keep the window open during temperature testing.
Solution Approach 2:
The patent introduces an intermediary mechanism in the form of controllable switches within the test structures. These switches act as mediators between the internal circuit nodes and the external probe pads, allowing selective connection or disconnection. This intermediary layer enables temperature testing with the window closed while maintaining the capability to access internal signals through the probe needle when required.
2Manufacturing precision
If changes are made with a focused ion beam to implement trimming, then adjustments can be made to circuit parameters, but the changes cannot easily be reversed
Solution Approach 1:
The patent applies dynamics by implementing switchable test structures that can dynamically change their connection state. Instead of permanent FIB modifications, the circuit includes controllable switches that can be programmed to open or close connections as needed. This dynamic configuration allows trimming adjustments to be made and easily reversed by changing the switch states through programming, eliminating the irreversibility problem of FIB changes.
3Measurement precision
If the packaging window is kept open to allow probe needle access, then internal signals can be tested, but the testing is not robust under various environmental conditions
Solution Approach 1:
The patent applies preliminary action by pre-configuring the test structures with switchable connections during packaging. The switches are programmed to appropriate states before environmental testing begins, allowing the window to remain closed throughout testing while still enabling signal access when needed. This preliminary configuration ensures testing robustness under various environmental conditions including temperature, voltage, and mechanical stress.
Solution Approach 2:
The patent introduces controllable switches as intermediaries between internal circuit nodes and external probe pads. These switches enable selective access to internal signals without requiring the packaging window to be open. By acting as mediators, they allow the package to remain sealed during environmental testing while still providing the capability to probe internal signals when required, thus improving testing reliability.
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 robust evaluation of integrated circuits under various conditions, including temperature, voltage, and mechanical stress, with reduced cost and time, and allows for precise trimming and adjustment of parameters like frequency and voltage without the need for focused ion beam modifications.
Implementation Method 1
test structures with CMOS transmission gates that can be activated by a probe needle to switch between open and closed states
Data Source
AI summary
A test structure (200) in an integrated circuit (100) includes a probe pad (210) disposed at a surface of a die (102) of the integrated circuit, a transmission gate (202) for connecting portions of an electronic circuit within the integrated circuit in response to a momentary signal applied to the probe pad, a first inverter (221) having an input coupled to the probe pad and having an output coupled to a control input of the transmission gate, and a second inverter (222) having an input coupled to an output of the first inverter and having an output coupled to another control input of the transmission gate. The output of the second inverter is coupled to the input of the first inverter. Upon power-up, the transmission gate is open. After the momentary signal is applied to the probe pad, the transmission gate closes and remains closed until power is disconnected.