Vertical Membrane Pressure Sensor Wafer Yield
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Solution Overview
Problem
The high cost and complexity of manufacturing pressure sensors due to the expensive silicon wafers and multiple processing steps result in high costs per functional die, necessitating a reduction in die size and improvement in manufacturing reliability to increase the number of functional dies per wafer.
Innovation Solution
The use of vertical membranes instead of conventional horizontal membranes, integrated circuit technologies for well-controlled manufacturing, and a two-wafer structure to form pressure sensors, reducing manufacturing costs and increasing yield, with components placed on the top and inside surfaces for enhanced sensitivity and protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If conventional horizontal membranes are used, then the membrane can be manufactured with standard processes, but the lateral dimensions are large resulting in fewer dies per wafer and higher cost
Solution Approach 1:
The patent transitions from a conventional horizontal membrane configuration to a vertical membrane configuration. This dimensional change allows the membrane to extend in the vertical direction rather than occupying large lateral space, thereby reducing the footprint on the wafer and enabling more dies to be manufactured per wafer while maintaining the same membrane area and functionality.
2Manufacturing precision
If multiple processing steps with expensive equipment and chemicals are used, then the pressure sensor can be manufactured with high precision, but the manufacturing cost increases
Solution Approach 1:
The patent modifies the geometric parameters of the membrane structure by changing from horizontal to vertical orientation. This parameter change enables the use of simplified manufacturing processes that require fewer processing steps and less expensive equipment and chemicals, while still achieving the required manufacturing precision through the inherent advantages of the vertical configuration.
3Productivity
If die size is reduced to increase dies per wafer, then the cost per die decreases, but the manufacturing reliability may be compromised
Solution Approach 1:
By changing the membrane orientation to vertical, the patent enables reduced die lateral dimensions without compromising manufacturing reliability. The vertical configuration maintains the essential membrane functionality while fitting into a smaller footprint, allowing more dies per wafer to be manufactured with the same reliable processes.
4Area of moving object
If vertical membranes are used, then the lateral dimensions are reduced allowing more dies per wafer, but the manufacturing process becomes more complex
Solution Approach 1:
The patent inverts the conventional horizontal membrane structure to a vertical orientation. This inversion simplifies the overall device structure by eliminating the need for large lateral extensions and complex support structures required by horizontal membranes, while the vertical configuration naturally provides structural stability and ease of integration with standard semiconductor fabrication processes.
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
This approach reduces the cost of each functional pressure sensor die, increases the number of functional dies per wafer, and enhances sensitivity and reliability, making pressure sensors more cost-effective and efficient to produce.
Implementation Method 1
When a pressure sensor in a pressure sensing device experiences a pressure, the membrane responds by changing shape
Implementation Method 2
As the membrane distorts under pressure, the resistance of the resistors also changes. This change results in an output of the Wheatstone bridge
Data Source
AI summary
Pressure sensors having vertical diaphragms or membranes. A vertical diaphragm may be located in a first silicon wafer between a first and second cavity, where the first and second cavities are covered by a second silicon wafer. One or more active or passive devices or components may be located on a top of the vertical diaphragm.