Shared-Pad Four-Terminal Resistance Layout for Wafer Area Savings
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Solution Overview
Problem
Existing four-terminal resistance testing structures in semiconductor manufacturing require multiple pads, consuming significant wafer area and increasing costs due to the need for four separate pads per resistor, while two-terminal methods suffer from inaccurate resistance measurements due to parasitic series resistance.
Innovation Solution
A four-terminal resistance testing structure where tested resistors are connected in series, sharing at least one pad between adjacent resistors, allowing each resistor to have four test terminals, with shared sense terminals having zero current, thereby reducing the number of pads required.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If four separate pads are used for each resistor in four-terminal resistance testing, then measurement accuracy is improved by eliminating parasitic series resistance influence, but wafer area consumption increases significantly
Solution Approach 1:
The patent merges the sense terminals of adjacent resistors by connecting them together, forming shared sense terminals. This allows multiple resistors to share common pads for sensing, reducing the total pad count from 4N to approximately 2N where N is the number of resistors. The force terminals remain separate for each resistor to maintain measurement accuracy while the shared sense terminals eliminate the need for dedicated sense pads for each resistor.
Solution Approach 2:
The shared sense terminals serve multiple functions by being connected to multiple resistors simultaneously. A single pad structure performs the sensing function for multiple adjacent resistors, making it a multi-functional element that reduces overall structure complexity and area consumption while maintaining the four-terminal measurement capability.
2Measurement precision
If four pads are allocated per resistor structure, then accurate resistance measurement is achieved through four-terminal method, but the number of pads and test keys increases
Solution Approach 1:
Adjacent resistors share common sense terminals by connecting their sense pads together. This merging reduces the total number of discrete pad structures required while maintaining the four-terminal measurement configuration for each resistor. The force terminals remain individually connected to each resistor to preserve measurement independence and accuracy.
3Area of stationary object
If two-terminal resistance testing is used, then wafer area is reduced by using fewer pads, but measurement accuracy deteriorates due to parasitic series resistance
Solution Approach 1:
The measurement function is segmented into two distinct terminal pairs: force terminals for current injection and sense terminals for voltage measurement. This segmentation allows the sense terminals to be shared among multiple resistors without affecting measurement accuracy, as the sense function is separated from the force function. The shared sense terminals reduce area while the dedicated force terminals maintain measurement precision.
Data Source
AI summary
The present application discloses a four-terminal resistance testing structure. A test key includes a resistor string formed by connecting two or more tested resistors in series. Two ends of each tested resistor are respectively provided with one first pad. At least one of the two first pads of each tested resistor is shared as the first pad of an adjacent tested resistor. Each tested resistor includes two force terminals and two sense terminals. The two force terminals are formed by the first pads at the two ends of the tested resistor, and each of the two sense terminals is composed of a pad located at a position adjacent to the corresponding force terminal. The present application can reduce the number of pads and thus save the area on the premise of ensuring the measurement accuracy.