Integrated Circuit Sensor on Passivation Stack
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Integrating moisture-sensitive sensors into integrated circuits (ICs) poses a challenge as environmental sensors need to be in communicative contact with the environment, increasing the risk of moisture penetration and interfering with the correct operation of underlying circuit elements, while maintaining a moisture barrier is crucial to protect the IC.
Innovation Solution
A sensor is placed on the passivation stack with a via extending through it, connected to the metallization stack, ensuring the passivation stack remains moisture-impenetrable, and an electrode on the passivation stack is conductively coupled to the via, using tungsten vias and a high density plasma oxide and Si3N4 layers for protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If environmental sensors are integrated into the metallization stack, then sensor functionality is achieved, but moisture penetration risk increases
Solution Approach 1:
The patent divides the sensor structure into separate functional layers: the metallization stack contains the circuit elements, while the sensor is formed as a distinct structure on top of the passivation stack. This segmentation allows the sensor to access environmental moisture independently while the passivation stack protects the underlying metallization stack from moisture penetration.
Solution Approach 2:
The passivation stack serves as an intermediary barrier between the moisture-sensitive metallization stack and the environmental sensor. It selectively allows the sensor to detect environmental moisture while blocking moisture from reaching and damaging the circuit elements below.
2Object-affected harmful factors
If a moisture barrier layer is deposited over the metallization stack, then protection from moisture is achieved, but sensor access to environment is blocked
Solution Approach 1:
The structure is segmented into protected zones (metallization stack covered by passivation stack) and exposed zones (sensor on top of passivation stack). This allows simultaneous moisture protection for sensitive components and environmental access for the sensor through the via structure.
Solution Approach 2:
The sensor is positioned in a different spatial dimension (on top of the passivation stack rather than within the metallization stack), connected through a via. This dimensional arrangement allows the sensor to access the environment vertically while the passivation stack horizontally protects the underlying structures.
3Adaptability or versatility
If multiple sensors are integrated into the metallization layer, then multi-functionality is achieved, but partial removal of barrier layer is required
Solution Approach 1:
Each sensor is implemented as a separate structure on top of the passivation stack with its own via connection, rather than integrating sensors within the metallization layers. This segmentation maintains the integrity of the passivation stack's moisture barrier while allowing multiple independent sensors to access the environment.
Solution Approach 2:
Multiple sensors are arranged in the vertical dimension on top of the passivation stack rather than laterally within the metallization layers. This allows multiple sensors to be implemented without requiring lateral removal of the barrier layer, preserving its integrity.
Data Source
Figure 1
Figure 2(a)~2(c)
Figure 2(d)~2(f)
AI summary
Disclosed is an integrated circuit comprising a substrate (10) carrying a plurality of circuit elements; a metallization stack (12, 14, 16) interconnecting said circuit elements, said metallization stack comprising a patterned upper metallization layer comprising a first metal portion (20); a passivation stack (24, 26, 28) covering the metallization stack; and a sensor including a sensing material (40) on the passivation stack, said sensor being coupled to the first metal portion by a via (34) extending through the passivation stack. A method of manufacturing such an IC is also disclosed.