High-Ge SiGe Fin Formation via Shell Oxide Mediator
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Solution Overview
Problem
The challenge lies in forming high germanium content silicon germanium alloy fins on an insulator layer, as conventional methods face issues such as defectivity and non-uniform oxide removal, leading to fin detachment and excessive insulator layer recess, which complicates subsequent processing steps.
Innovation Solution
A method involving a first condensation process to form a silicon germanium alloy layer with a specific germanium content, followed by a nitride-containing hard mask layer formation, a second condensation process to create high germanium content fins and shell oxide structures, and controlled recessing of the shell oxide to maintain the insulator layer integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If condensation process is used to achieve high germanium content silicon germanium alloy fins, then germanium content is improved, but non-uniform oxide removal occurs leading to fin detachment and insulator layer recess
Solution Approach 1:
A shell oxide structure is formed as an intermediary protective layer on the sidewalls of the silicon germanium alloy fin during the condensation process. This shell oxide prevents direct exposure and potential detachment of the high germanium content fin, while allowing controlled recessing of the underlying insulator layer without causing fin detachment.
Solution Approach 2:
The shell oxide structure is formed preliminarily on the sidewalls of the silicon germanium alloy fin before the condensation process completes. This preliminary protective layer is then selectively recessed to the desired extent, preventing the harmful effects of non-uniform oxide removal while maintaining the high germanium content in the fin.
2Quantity of substance
If condensation process is used to achieve high germanium content silicon germanium alloy fins, then germanium content is improved, but excessive insulator layer recess occurs
Solution Approach 1:
The shell oxide structure serves as a mediator that controls the recessing process. By forming the shell oxide on the sidewalls and then selectively recessing it, the insulator layer recess is limited to a controlled amount, preventing excessive recess that would complicate subsequent processing steps.
Solution Approach 2:
The shell oxide structure provides localized protection only on the sidewalls of the fin, allowing differential treatment of different regions. The sidewalls receive protective coverage while the top and bottom regions can be processed differently, enabling precise control over the insulator layer recess depth.
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 effectively avoids unwanted recessing and fin detachment, enabling the formation of high germanium content silicon germanium alloy fins with improved structural integrity and process stability.
Implementation Method 1
a second condensation process is performed to convert a portion of the silicon germanium alloy layer into a silicon germanium alloy fin of a second germanium content that is greater than the first and other portions of the silicon germanium alloy layer into a shell oxide structure
Data Source
AI summary
A method of forming high germanium content silicon germanium alloy fins with controlled insulator layer recessing is provided. A silicon germanium alloy (SiGe) layer having a first germanium content is provided on a surface of an insulator layer using a first condensation process. Following the formation of a hard mask layer portion on the SiGe layer, a second condensation process is performed to convert a portion of the SiGe layer into a SiGe fin of a second germanium content that is greater than the first germanium content and other portions of the SiGe layer into a shell oxide structure located on sidewalls of the SiGe fin. After forming a fin placeholder material, a portion of each shell oxide structure is removed, while maintaining a lower portion of each shell oxide structure at the footprint of the SiGe fin.