Epitaxial Source/Drain Formation Without Non-Crystalline Nodules
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Solution Overview
Problem
As semiconductor devices continue to shrink in size, challenges arise in forming epitaxial source/drain regions without damaging the crystalline structure, leading to non-crystalline nodules that affect device performance.
Innovation Solution
A method involving epitaxial growth of semiconductor materials followed by cleaning processes to remove nodules, ensuring the formation of crystalline source/drain regions without damaging the underlying structures, using techniques like chemical mechanical polishing and selective etching to maintain device integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If epitaxial source/drain regions are formed by depositing crystalline semiconductor material, then device integration density is improved, but non-crystalline nodules form and damage the crystalline structure
Solution Approach 1:
A liner layer is deposited over the gate structure before forming the epitaxial source/drain regions. This preliminary protective layer prevents non-crystalline nodules from forming on the gate structure during the epitaxial growth process, thereby maintaining crystalline structure integrity while enabling high integration density
Solution Approach 2:
The liner layer acts as an intermediary between the gate structure and the epitaxial semiconductor material. It provides a controlled interface that prevents unwanted nodule formation while allowing the epitaxial regions to grow with proper crystalline structure
2Reliability
If cleaning processes are performed to remove non-crystalline nodules, then device performance is improved, but the epitaxial regions may be damaged
Solution Approach 1:
The liner layer is deposited in advance to prevent nodule formation on the gate structure. This preliminary protective measure eliminates the need for aggressive cleaning processes that could damage the epitaxial regions, thereby maintaining both device performance and epitaxial region integrity
3Productivity
If minimum feature size is reduced to increase integration density, then more components can be integrated, but additional challenges arise in maintaining crystalline structure
Solution Approach 1:
The liner layer is deposited before epitaxial growth to pre-establish protective coverage. This preliminary action simplifies the overall process by preventing nodule formation upfront, reducing the need for complex cleaning steps and maintaining crystalline structure even as feature sizes are reduced for higher integration density
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
The method effectively forms high-quality epitaxial source/drain regions, enhancing device performance by preventing non-crystalline nodules and maintaining the integrity of the semiconductor layers.
Implementation Method 1
depositing a semiconductor material to form epitaxial source/drain regions
Implementation Method 2
cleaning processes to remove non-crystalline nodules, ensuring minimal damage to the epitaxial regions
Implementation Method 3
cleaning processes to remove non-crystalline nodules, ensuring minimal damage to the epitaxial regions and other features
Data Source
AI summary
In an embodiment, a method includes forming a first semiconductor fin and a second semiconductor fin over a front-side of a substrate; etching a first recess in the first semiconductor fin and a second recess in the second semiconductor fin; forming a first epitaxial region in the first recess and first epitaxial nodules along sidewalls of the first recess; forming a second epitaxial region in the second recess and second epitaxial nodules along sidewalls of the second recess; flowing first precursors to remove the first epitaxial nodules; depositing an interlayer dielectric over the first epitaxial region and the second epitaxial region; etching a first opening in the interlayer dielectric to expose the first epitaxial region; forming a first epitaxial cap on the first epitaxial region and third epitaxial nodules over the interlayer dielectric; and flowing second precursors to remove the third epitaxial nodules.