Thermopile Test Structure with Embedded Temperature-Sensitive Elements
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Solution Overview
Problem
Prior art thermopile characterization methods require back-etching to form a membrane portion, making wafer handling difficult, increasing the risk of damage and restricting thermopile geometries, leading to inaccurate early-stage characterization and increased waste and cost.
Innovation Solution
Integrated thermopile test structures with temperature-sensitive elements positioned below the thermopile, allowing characterization without back-etching, enabling robust monitoring and identification of defects at the wafer testing stage without impacting the desired thermopile layout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If back-etching is performed to form a membrane portion for thermopile characterization, then temperature difference measurement capability is improved, but wafer handling difficulty increases and risk of damage increases
Solution Approach 1:
Temperature-sensitive elements are embedded in the substrate during the fabrication process before the wafer is completed and before back-etching occurs. This preliminary action allows characterization capabilities to be established early, avoiding the need to perform back-etching specifically for characterization purposes.
Solution Approach 2:
Temperature-sensitive elements act as intermediary components that enable temperature difference measurement without requiring the membrane structure. These elements are positioned between the thermopile and the substrate, providing the measurement function while allowing the wafer to maintain its intact structure for safe handling.
2Measurement precision
If back-etching is performed to form a membrane portion, then thermopile characterization capability is improved, but manufacturing time and cost increase
Solution Approach 1:
The characterization functionality is merged into the main fabrication process by embedding temperature-sensitive elements during standard fabrication steps. This combines the characterization capability with the manufacturing process itself, eliminating the need for separate back-etching operations and additional processing time.
Solution Approach 2:
Temperature-sensitive elements are incorporated during the fabrication process before the wafer is completed. This preliminary action allows characterization capabilities to be established early in manufacturing, enabling early-stage characterization without requiring additional back-etching steps that would extend manufacturing time and increase costs.
3Measurement precision
If temperature-sensitive elements are positioned in upper conductive layers shared with thermopile, then characterization capability is improved, but thermopile geometry flexibility is restricted
Solution Approach 1:
Temperature-sensitive elements are positioned in the vertical dimension within the substrate, below the thermopile structure, rather than in the horizontal plane within the same conductive layers. This dimensional separation allows the thermopile to maintain its desired geometries in the upper layers while temperature-sensitive elements occupy space in the lower substrate region.
Solution Approach 2:
The device structure is segmented into distinct functional regions: the thermopile in the upper conductive layers for sensing functionality, and temperature-sensitive elements in the lower substrate for characterization functionality. This segmentation allows each component to be optimized independently without geometric constraints from shared layers.
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 efficient and accurate characterization of thermopile sensitivity and operation at the wafer testing stage, reducing time and cost by avoiding back-etching and allowing for earlier detection of defective thermopile fabrication, thus improving semiconductor foundry processes.
Implementation Method 1
The thermoelectric effect is the direct conversion of temperature gradients to electric voltage and vice versa. As such, a thermoelectric device, such as a thermocouple, generates voltage when there is a different temperature between the junction of the two different conductors and a region occupied by the two conductors away from the junction.
Implementation Method 2
In operation testing, a voltage is applied to the heater to increase the temperature of the membrane portion
Data Source
AI summary
A semiconductor product comprising: a semiconductor substrate and a test structure, the test structure comprising: a thermopile and at least one temperature sensitive element, the at least one temperature sensitive element being located in the substrate, or between the substrate and the thermopile.