Epitaxial Layer Shape Control via Inert Gas Thermal Treatment
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Solution Overview
Problem
In semiconductor fabrication, the rounding of epitaxial layers during the epitaxial growth process leads to an increased gate channel length and reduced stress effect, compromising the performance of MOS transistors, particularly at advanced nodes like 65-nm and beyond.
Innovation Solution
A method involving a thermal treatment in an inert gas atmosphere at a high temperature is performed after recess formation to alter hydrogen bonding with the silicon substrate, preventing hydrogen-induced silicon migration and allowing the epitaxial layer to maintain a desired shape during subsequent growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If selective epitaxial growth is performed directly after recess formation, then the epitaxial growth process can be completed efficiently, but the epitaxial layer rounds off and deviates from the original recess shape
Solution Approach 1:
A thermal treatment process is performed as a preliminary step before the epitaxial growth process. This thermal treatment modifies the bonding or adsorption relation of hydrogen to the silicon substrate, preparing the surface in advance to prevent hydrogen-induced silicon migration during subsequent epitaxial growth, thereby maintaining the recess shape precision while enabling efficient epitaxial growth.
2Manufacturing precision
If thermal treatment is performed in inert gas atmosphere, then hydrogen bonding is altered to prevent silicon migration, but an additional process step is required
Solution Approach 1:
The thermal treatment process is conducted in an inert gas atmosphere (such as nitrogen or argon), which prevents unwanted chemical reactions while allowing the thermal energy to modify hydrogen bonding. This inert environment enables precise control of the thermal treatment to alter hydrogen-silicon bonding relations without introducing contaminants, thereby maintaining epitaxial layer shape control while integrating smoothly into existing fabrication processes.
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 ensures the epitaxial layer retains a designed shape, enhancing the stress effect on the gate channel and improving transistor performance by maintaining the intended recess geometry.
Implementation Method 1
a thermal treatment process is performed on the recess in a gas atmosphere including an inert gas at a first temperature
Implementation Method 2
thermal treatment process is performed on the recess in a gas atmosphere including an inert gas at a first temperature to alter or modify the bonding or adsorption relation of hydrogen
Implementation Method 3
a thermal treatment process is performed on the recess in a gas atmosphere including an inert gas
Implementation Method 4
an epitaxy growth process is performed at a second temperature to form a silicon-containing epitaxial layer in the recess
Data Source
AI summary
A method of fabricating a semiconductor structure, in which after an etching process is performed to form at least one recess within a semiconductor beside a gate structure, a thermal treatment is performed on the recess in a gas atmosphere including an inert gas before a silicon-containing epitaxial layer is formed in the recess through an epitaxy growth process.