Semiconductor Test Unit for Post-Dicing Characteristic Measurement
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Solution Overview
Problem
Conventional semiconductor devices struggle to accurately measure characteristic variations of elements on a wafer without increasing chip area, especially after dicing, and fail to capture spatial variations due to limited Test Element Groups (TEGs) arrangement.
Innovation Solution
Incorporating a test unit within the semiconductor device that allows for measuring element characteristics by keeping the main circuit unit's power consumption at zero or constant, enabling accurate power consumption measurement linked to element characteristics, and using a characteristic management system to store measurement data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If TEGs are arranged on the scribe line of the wafer to measure characteristic variations, then the chip area does not increase, but the measurement cannot be performed after dicing
Solution Approach 1:
The test unit is merged with the main circuit unit and integrated into the chip after dicing. The test unit includes elements to be measured that are combined with the main circuit, allowing measurement to be performed on the finished chip rather than requiring separate TEGs on the scribe line. This integration enables post-dicing measurement while maintaining compact chip area.
2Measurement precision
If the number of TEGs is increased to capture spatial variations in the wafer plane, then measurement accuracy improves, but measurement time increases and jig complexity increases
Solution Approach 1:
The test unit is designed with multi-functionality to capture various spatial variations using a minimal number of elements. The controller selectively activates different elements within the test unit to measure characteristics at multiple locations and conditions, replacing the need for numerous separate TEGs. This universal design reduces measurement time while maintaining the ability to detect doughnut-shaped and other spatial variation patterns.
Solution Approach 2:
The controller dynamically selects and activates specific elements to be measured within the test unit based on the measurement requirements. Rather than having fixed, numerous TEGs, the system adaptively configures which elements are active during measurement, optimizing the measurement process for different spatial variation patterns and reducing overall measurement time.
3Reliability
If a dedicated measuring pad is provided for each chip to enable post-dicing measurement, then measurement after dicing becomes possible, but chip area increases considerably
Solution Approach 1:
The test unit is merged with the main circuit unit and shares the same chip substrate and power supply structure. The elements to be measured are integrated within the chip area alongside the main circuit, eliminating the need for separate dedicated measuring pads on each chip. This integration enables post-dicing measurement while avoiding considerable chip area increase.
4Device complexity
If power consumption of the main circuit unit is not controlled during measurement, then measurement setup is simpler, but accurate power consumption measurement of the element cannot be obtained
Solution Approach 1:
The controller periodically switches the main circuit unit between operational states and measurement states. During measurement, the controller stops or reduces operation of the main circuit unit to minimize its power consumption, then selectively activates elements to be measured in the test unit. This periodic control enables accurate power consumption measurement of individual elements by isolating their power draw from the main circuit.
Data Source
AI summary
A plurality of series circuits each consisting of a current-carrying element and an element to be measured are provided between a power supply potential VDD and a ground potential VSS. The current-carrying elements are supplied with a test signal commonly, and corresponding selection signals, respectively. After a mode is set so that power consumption of a main circuit unit included in a semiconductor device is substantially zero or almost constant, the elements to be measured are energized sequentially and, in this state, a power supply current that flows through the semiconductor device is measured sequentially. Accordingly, it is possible to accurately know the power consumption of the element to be measured and it is also possible to know the characteristics of the element to be measured based thereon.