Semiconductor Structure with Dummy Layer for MEMS
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Solution Overview
Problem
The surface roughness and abnormal grain formation in aluminum nitride and scandium-doped aluminum nitride layers during semiconductor manufacturing processes, such as lithography and etching, lead to poor c-axis orientation and increased energy loss in piezoelectric layers, affecting the performance of microelectromechanical systems (MEMS) devices.
Innovation Solution
Incorporating dummy layers with planarized surfaces to provide a smooth interface for subsequent piezoelectric layer formation, reducing surface roughness to less than 0.4 nm and preventing the amplification of undesired c-axis orientation, thereby enhancing the crystalline structure and piezoelectric properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If lithography and etching processes are performed on aluminum nitride and scandium-doped aluminum nitride layers, then MEMS device performance is improved, but surface roughness increases and abnormal grains form
Solution Approach 1:
A planarized dummy layer is formed over the piezoelectric layer before subsequent processing steps. This preliminary action creates a smooth surface that prevents abnormal grain formation and maintains low surface roughness during lithography and etching processes, resolving the contradiction between device performance and manufacturing precision
2Loss of energy
If scandium is doped into aluminum nitride to enhance piezoelectric properties, then energy density increases, but abnormal grain formation occurs
Solution Approach 1:
A dummy layer is introduced as an intermediary between the scandium-doped piezoelectric layer and the overlying structures. This intermediary layer isolates the piezoelectric layer from direct exposure to processing conditions that cause abnormal grain formation, allowing the benefits of scandium doping (high energy density) to be realized without the harmful compositional changes
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
The use of dummy layers results in highly oriented piezoelectric layers with reduced energy loss, improving the quality and performance of MEMS devices, sensors, and other applications by maintaining a smooth surface and preventing the formation of abnormal grains.
Implementation Method 1
Thin film piezoelectric materials may offer a number of advantages in microelectromechanical systems (MEMS), due to the large motions that can be generated
Implementation Method 2
a first piezoelectric layer is formed over the substrate
Data Source
AI summary
A semiconductor structure is provided. The semiconductor structure includes a substrate, a first piezoelectric layer, and a first dummy layer. The first piezoelectric layer is over the substrate, and the first piezoelectric layer has a first top surface. The first dummy layer is over the first piezoelectric layer, and the first dummy layer has a second top surface. And an average roughness of the first top surface is greater than an average roughness of the second top surface. A method for manufacturing the semiconductor structure is also provided.