CMOS Micromechanical Sensor Integration via Structured Sacrificial Layer
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The integration of micromechanical systems, such as pressure sensors, into CMOS technology poses challenges due to the complexity of manufacturing processes and the need to preserve existing integration schemes with minimal development effort, especially when migrating to new technology nodes like the 130 nm node.
Innovation Solution
A method involving the formation of a structured sacrificial layer, followed by a functional layer that is partially covering the sacrificial layer, with a thermal treatment to activate doping atoms and restructure the atomic structure, creating a cavity and tension in the functional layer, which allows for the integration of micromechanical systems with reduced complexity and compatibility with CMOS processes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If micromechanical structures (lamellas, membranes) are integrated into CMOS substrate, then functional integration is improved, but manufacturing complexity increases
Solution Approach 1:
A sacrificial layer is deposited on the substrate before forming the functional layer. This preliminary structure enables subsequent cavity formation and micromechanical element creation without requiring complex post-processing steps, thus integrating micromechanical structures while maintaining manufacturing simplicity
Solution Approach 2:
The sacrificial layer acts as an intermediary element that facilitates the integration of micromechanical structures. It is temporarily introduced to define cavity regions, support functional layer formation, and then removed to create the final micromechanical structure, simplifying the overall manufacturing process
2Adaptability or versatility
If new integration schemes for micromechanical systems are developed, then integration capability is improved, but development effort increases
Solution Approach 1:
The method uses standard CMOS-compatible processes (sacrificial layer deposition, functional layer formation, etching, thermal treatment) that can be integrated into existing CMOS production lines. This universal approach enables micromechanical integration without requiring entirely new development schemes, reducing development effort while maintaining integration capability
3Strength
If thermal treatment is applied to create tension in functional layer, then mechanical properties are improved, but process temperature increases
Solution Approach 1:
Thermal treatment is applied to activate doping atoms and restructure the atomic structure of the functional layer, creating the necessary mechanical tension. By controlling temperature, time, and atmospheric parameters during thermal treatment, the desired mechanical properties are achieved while managing the temperature impact
4Manufacturing precision
If sacrificial layer is removed to create cavity, then micromechanical structure formation is improved, but manufacturing steps increase
Solution Approach 1:
The sacrificial layer is selectively removed through etch holes to create cavities and define micromechanical structures. This extraction approach allows precise cavity formation with clean boundaries while using a single removable sacrificial layer structure, minimizing the number of manufacturing steps required
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 enables efficient integration of micromechanical systems with reduced complexity and minimal impact on existing CMOS integration schemes, facilitating the integration of pressure sensors and other sensors with improved mechanical and electrical properties.
Implementation Method 1
a thermal treatment is conducted, wherein the thermal treatment may activate doping atoms of the functional layer and provides a restructuring of the atomic structure of the functional layer. The restructuring of the atomic structure further creates a tension in the functional layer
Implementation Method 2
The restructuring of the atomic structure further creates a tension in the functional layer
Data Source
AI summary
A method for manufacturing a micromechanical system includes forming in a Front-End-of-Line (FEOL) process transistors in a transistor region; after the FEOL-process, forming a sacrificial layer; structuring the sacrificial layer to form a structured sacrificial layer; forming a functional layer at least partially covering the structured sacrificial layer; and removing the sacrificial layer to create a cavity.