MOSCAP STI Etching Layout for Thermal-Stable Capacitance Tuning
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Solution Overview
Problem
The thermal anneal process used in fabricating metal-oxide-semiconductor capacitors (MOSCAPs) can cause chemical degeneration or physical embrittlement in layers other than the binary metal layer, and induces poor thermal stability in the binary metal layer, necessitating strict control of temperature, duration, and atmosphere, increasing process difficulty and cost.
Innovation Solution
A method for fabricating a semiconductor device that includes forming a fin-shaped structure on a MOSCAP region, creating a shallow trench isolation around the substrate and fin-shaped structures, and performing etching processes to adjust the height of the trench isolation on both the non-MOSCAP and MOSCAP regions, allowing for the adjustment of the overall area and capacitance of the MOSCAP device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal anneal process is conducted on the binary metal layer to achieve adequate work function, then the work function of the metal layer is improved, but chemical degeneration or physical embrittlement occurs in other layers and thermal instability is induced in the binary metal layer
Solution Approach 1:
The patent changes the material parameter from binary metal to ternary metal alloy (e.g., Pt-Pd-Ag, Pt-Pd-Au), which fundamentally alters the thermal stability characteristics while maintaining adequate work function. This compositional parameter change resolves the contradiction by providing both the required electrical property (work function) and improved thermal stability simultaneously.
Solution Approach 2:
The patent employs composite material structure by using ternary metal alloys combining multiple elements (Pt, Pd, Ag, Au) with complementary properties. The composite nature of the alloy provides both the necessary work function for MOSCAP operation and enhanced thermal stability, eliminating the need for post-deposition thermal annealing that causes damage to other layers.
2Reliability
If strict control of temperature, duration, and atmosphere is implemented during thermal anneal process, then the work function is maintained, but process difficulty and cost increase
Solution Approach 1:
The patent performs preliminary action by incorporating the desired work function and thermal stability properties directly into the metal layer composition during the deposition process. The ternary alloy is designed beforehand to eliminate the need for subsequent thermal annealing, thereby simplifying the manufacturing process and reducing both process complexity and cost while maintaining reliable electrical characteristics.
Data Source
AI summary
A method for fabricating a semiconductor device includes the steps of first providing a substrate having a non-metal-oxide semiconductor capacitor (non-MOSCAP) region and a MOSCAP region, forming a fin-shaped structure on the MOSCAP region, forming a shallow trench isolation (STI) around the substrate and the fin-shaped structure, performing a first etching process to remove part of the STI on the MOSCAP region, and then performing a second etching process to remove part of the STI on the non-MOSCAP region and the MOSCAP region.