AlN Thin-Film Sputtering With Positive Bias for CMOS Integration
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Solution Overview
Problem
Existing methods for depositing aluminum nitride (AlN) thin films face challenges in achieving high piezo characteristics at low process temperatures compatible with CMOS processes, making it difficult to implement a one-chip type CMOS/AlN thin film manufacturing process.
Innovation Solution
A method involving the application of a bias positive voltage to the base substrate during the sputtering process allows for the deposition of an AlN thin film at CMOS-compatible temperatures, enabling adjustable thickness and vertical growth of the AlN(002) surface, which enhances piezo characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a negative voltage is applied to the substrate or Mo is used as a low substrate to obtain AlN(002) surface with high piezo characteristics, then piezo characteristics are improved, but the process temperature inevitably rises making it incompatible with CMOS processes
Solution Approach 1:
The patent changes the voltage parameter from negative to positive, and adjusts the voltage magnitude (5-50V) to achieve AlN(002) surface growth with excellent piezo characteristics at low temperatures (below CMOS-compatible process temperature), resolving the contradiction between piezo characteristics and process temperature
Solution Approach 2:
The patent introduces dynamic control of the substrate voltage during the sputtering process, allowing real-time adjustment of the voltage parameter to optimize both piezo characteristics and temperature compatibility, enabling flexible process control for CMOS integration
2Ease of manufacture
If separate fabrication of CMOS chip and AlN thin film-based sensor is performed (two-chip type), then manufacturing flexibility is maintained, but integration complexity and device complexity increase
Solution Approach 1:
The patent merges the CMOS chip fabrication process with the AlN thin film deposition process into a single integrated flow, allowing both components to be manufactured on the same substrate using compatible processes, thereby reducing device complexity while maintaining manufacturing flexibility
Solution Approach 2:
The patent develops a universal sputtering process that can fabricate both CMOS-compatible structures and high-quality AlN piezoelectric layers using the same equipment and process conditions, enabling multi-functionality in a single manufacturing line
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 the growth of an AlN surface with excellent piezo characteristics at low temperatures, facilitating the fabrication of one-chip sensor devices compatible with CMOS processes and allowing for horizontal sensor structures.
Implementation Method 1
depositing an AlN thin film on the insulating layer through a sputtering process
Implementation Method 2
applying a bias positive voltage to the base substrate such that the AlN thin film has an adjustable deposition thickness
Data Source
AI summary
A method of depositing an AlN thin film according to an embodiment of the disclosure comprises: a step of forming an insulating layer on a base substrate; and a step of depositing an AlN thin film on the insulating layer through a sputtering process, wherein the step of depositing the AlN thin film is performed through a continuous deposition type, at lower than a CMOS-compatible process temperature and in a state of applying a bias positive voltage to the base substrate such that the AlN thin film has an adjustable deposition thickness. Therefore, an embodiment of the disclosure is advantageous in that an AlN thin film having excellent piezo characteristics can be obtained at a low process temperature compatible with a CMOS process.