MEMS Manufacturing Using Amorphous Carbon Polishing Stop
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Solution Overview
Problem
Current MEMS device manufacturing techniques face challenges with low polishing speed and precision issues during chemical mechanical polishing (CMP) of sacrificial material layers, leading to prolonged processing times and potential loss of semiconductor dielectric layer thickness due to the inert nature of materials like amorphous carbon.
Innovation Solution
The method involves forming and patterning sacrificial layers prior to dielectric layers, allowing for direct exposure and removal without the need for CMP on the sacrificial material, thereby reducing production cycle and improving efficiency by using amorphous carbon as a polishing stop layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If chemical mechanical polishing (CMP) is used to polish sacrificial material layer, then the sacrificial material can be removed, but the polishing speed is unacceptably low and the polishing process cannot be stopped precisely
Solution Approach 1:
The patent changes the material parameter of the sacrificial layer from amorphous carbon to silicon oxide, which has fundamentally different polishing characteristics. Silicon oxide can be polished at high speed with good controllability using CMP, while amorphous carbon exhibits unacceptably low polishing speed and cannot be stopped precisely. This material substitution resolves both the low polishing speed and the inability to stop polishing precisely.
Solution Approach 2:
The patent applies different material properties to different functional layers: the sacrificial layer uses silicon oxide for easy polishing, while the semiconductor dielectric layer maintains its original material properties. This local differentiation allows the sacrificial layer to be polished selectively with high speed and precision without affecting other layers.
2Productivity
If sacrificial material layer is polished using CMP process, then the sacrificial material is removed, but the polishing period is prolonged
Solution Approach 1:
By changing the sacrificial material from amorphous carbon to silicon oxide, the polishing time is dramatically reduced. Silicon oxide exhibits high polishing speed with CMP process, transforming a prolonged polishing period into a short, efficient process step that enhances overall production efficiency.
3Productivity
If sacrificial material layer is polished using CMP process, then the sacrificial material is removed, but loss on semiconductor dielectric layer thickness occurs
Solution Approach 1:
The patent creates local differentiation in material properties where the sacrificial layer (silicon oxide) has high polishability while the semiconductor dielectric layer maintains its structural integrity. This allows the polishing process to selectively remove the sacrificial material with high efficiency while preserving the dielectric layer thickness through precise stopping capability.
Solution Approach 2:
The silicon oxide sacrificial layer acts as an intermediary that facilitates the polishing process. It provides a removable layer that can be polished away to expose the underlying structure without causing excessive loss to the semiconductor dielectric layer, enabling precise process control.
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 enhances the polishing speed of sacrificial materials and avoids over-polishing, reducing production time and maintaining semiconductor dielectric layer thickness, thus improving the overall efficiency of MEMS device manufacturing.
Implementation Method 1
polishing the first dielectric layer until the first sacrificial layer is exposed by using a chemical mechanical polishing process
Implementation Method 2
Sacrificial materials commonly used in the art include amorphous carbon, some organic polymeric materials, and the like, which may be easily removed as gas using an ashing process
Data Source
AI summary
A method for manufacturing a micro-electro-mechanical system (MEMS) device is provided. The method comprises: providing a semiconductor substrate, the semiconductor substrate having a metal interconnection structure (100) formed therein; forming a first sacrificial layer (201) on the surface of the semiconductor substrate, the material of the first sacrificial layer is amorphous carbon; etching the first sacrificial layer to form a first recess (301); covering and forming a first dielectric layer (401) on the surface of the first sacrificial layer; thinning the first dielectric layer by a chemical mechanical polishing (CMP) process, until exposing the first sacrificial layer; forming a micromechanical structure layer (500) on the surface of the first sacrificial layer and exposing the first sacrificial layer, wherein a part of the micromechanical structure layer is connected to the first dielectric layer. The method avoids polishing the amorphous carbon, shortens the period of production, and improves the production efficiency.