Crystalline Semiconductor Layer via MgO Seed in BEOL Processing
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Solution Overview
Problem
Forming a crystalline semiconductor layer over an amorphous dielectric layer, such as silicon oxide, is challenging due to the lack of a crystalline lattice link and the unsuitability of high-temperature annealing in back-end-of-line processes.
Innovation Solution
A crystalline dielectric seed layer, like magnesium oxide, is formed over an amorphous inter-layer dielectric layer, followed by a nanosecond laser anneal process to crystallize an amorphous semiconductor layer, enabling the growth of a crystalline semiconductor layer at low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-temperature annealing is used to crystallize the semiconductor layer, then crystalline structure is achieved, but the process temperature is too high for back-end-of-line processes
Solution Approach 1:
The patent changes the temperature parameter from high-temperature annealing (>500°C) to low-temperature crystallization (<450°C) by introducing a crystalline seed layer that enables crystal growth at lower temperatures, making the process suitable for back-end-of-line integration
Solution Approach 2:
A crystalline dielectric seed layer is introduced as an intermediary between the amorphous inter-layer dielectric and the amorphous semiconductor layer. This seed layer provides a crystalline template that facilitates low-temperature crystallization of the semiconductor layer without requiring high-temperature annealing
2Reliability
If a crystalline semiconductor layer is formed over an amorphous dielectric layer, then device performance is improved, but the lack of crystalline lattice link prevents successful growth
Solution Approach 1:
The crystalline dielectric seed layer serves as a mediator that provides the missing crystalline lattice link between the amorphous inter-layer dielectric and the semiconductor layer, enabling successful epitaxial growth without requiring the substrate itself to be crystalline
Solution Approach 2:
The crystalline seed layer is formed in advance before depositing the semiconductor layer, preparing a ready-made crystalline template that will guide and facilitate the subsequent crystallization process when the semiconductor material is deposited
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 method allows for the successful formation of crystalline semiconductor layers in back-end-of-line processes, improving device integration and performance by providing a crystalline lattice link and maintaining low processing temperatures.
Implementation Method 1
a nanosecond laser anneal process to crystallize an amorphous semiconductor layer
Implementation Method 2
crystallize an amorphous semiconductor layer, enabling the growth of a crystalline semiconductor layer
Implementation Method 3
A crystalline semiconductor layer is then formed over the base layer
Data Source
AI summary
A crystalline channel layer of a semiconductor material is formed in a backend process over a crystalline dielectric seed layer. A crystalline magnesium oxide MgO is formed over an amorphous inter-layer dielectric layer. The crystalline MgO provides physical link to the formation of a crystalline semiconductor layer thereover.