Integrated Humidity Sensor Structure for Small-Footprint Chips
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Solution Overview
Problem
Conventional humidity sensors have a large footprint on semiconductor wafers, limiting their integration into other devices without increasing chip size, necessitating separate chips and processing steps, and requiring special packaging.
Innovation Solution
A method of forming a semiconductor device with electrodes and a bond pad in a dielectric region, where a moisture-sensitive dielectric layer fills trenches to create projections between electrodes, allowing for simultaneous formation and integration of a humidity sensor within the same dielectric region as the bond pad, using a barrier layer to prevent moisture ingress and corrosion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional humidity sensors are fabricated on a processed wafer surface, then the sensor can measure humidity using capacitance change, but the sensor occupies a large footprint area that limits integration into other devices
Solution Approach 1:
The patent combines the humidity sensor fabrication process with the IC chip fabrication process by forming both the sensor electrodes and the bond pad in the same dielectric region during the same processing steps. This merging of functions allows the sensor to be integrated into the chip without requiring additional wafer area or separate processing, thereby reducing the footprint while maintaining measurement capability.
Solution Approach 2:
The dielectric region is designed to serve multiple functions: it contains both the humidity sensor electrodes and the bond pad structure. The same dielectric layer and processing steps are used to form both sensing elements and interconnect elements, making the structure universal and eliminating the need for separate dedicated sensor areas on the wafer.
2Ease of manufacture
If separate chips are used for humidity sensing, then the sensor can be fabricated independently, but additional processing steps and special packaging are required
Solution Approach 1:
The patent merges the humidity sensor fabrication with the IC chip fabrication by forming both structures simultaneously in the same dielectric region using the same processing steps. This eliminates the need for separate sensor chips and their associated packaging, reducing device complexity while maintaining ease of manufacture through standard IC processes.
3Measurement precision
If the moisture sensitive dielectric layer is formed to fill trenches between electrodes, then the sensitivity is enhanced through increased fringe capacitance, but the manufacturing process becomes more complex
Solution Approach 1:
The formation of the moisture-sensitive dielectric layer in the trenches is integrated into the standard IC fabrication process flow. The dielectric layer is deposited conformally to fill the trenches between electrodes, creating projections that enhance fringe capacitance and sensitivity. This approach achieves enhanced sensitivity without adding significant manufacturing complexity because it uses standard deposition and patterning techniques already employed in IC fabrication.
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 the integration of humidity sensors into semiconductor devices without increasing chip size, reducing manufacturing costs by allowing simultaneous fabrication during back-end-of-line processing and enhancing sensitivity through fringe capacitance increases.
Implementation Method 1
The dielectric layer may be formed of a material configured to absorb and retain water molecules at concentrations that are proportional to the ambient humidity
Implementation Method 2
forming a barrier layer over the electrodes
Data Source
AI summary
The disclosed subject matter relates generally to methods of forming a semiconductor device, such as a moisture sensor. A plurality of electrodes and a bond pad are formed in a dielectric region. A passivation layer is formed on each electrode in the plurality of electrodes and the bond pad. A barrier layer is formed on the passivation layer. A plurality of trenches are formed to extend through the barrier layer and into the dielectric region. Formation of the trenches simultaneously exposes an upper surface of the bond pad. A moisture sensitive dielectric layer is formed on the barrier layer. Formation of the moisture sensitive dielectric layer also fills the trenches to form a plurality of projections, each projection being formed between two electrodes in the plurality of electrodes.