Seeded Epitaxial Source/Drain Recesses to Prevent Seams and Voids
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Solution Overview
Problem
As semiconductor integrated circuits (ICs) scale down to smaller geometries, challenges arise in maintaining device performance and reliability due to increased functional density and decreased component sizes.
Innovation Solution
The formation of strained features in gate stacks for semiconductor devices, specifically through the use of a seed layer on top of an insulating layer in source/drain recesses, allows for epitaxial growth without seams or voids, enhancing device performance and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If semiconductor devices are scaled down to smaller geometries to increase functional density, then production efficiency and cost are improved, but device performance and reliability deteriorate due to increased defects and manufacturing challenges
Solution Approach 1:
A seed layer is formed on the insulating layer before epitaxial growth to prepare the surface in advance. This preliminary action ensures that the epitaxial layer grows seamlessly without defects, thereby maintaining device reliability even as devices are scaled down to smaller geometries for increased production efficiency
Solution Approach 2:
The seed layer acts as an intermediary between the insulating layer and the epitaxial layer. This intermediate layer facilitates seamless epitaxial growth by providing a suitable surface for crystal formation, preventing defects that would otherwise compromise device reliability during scaling
2Area of moving object
If component sizes are decreased to increase functional density, then chip area utilization is improved, but manufacturing precision deteriorates due to difficulty in creating smaller features
Solution Approach 1:
The seed layer is deposited beforehand to prepare a controlled, defect-free surface for subsequent epitaxial growth. This preliminary preparation enables precise formation of small features by ensuring uniform crystal nucleation and growth, thereby maintaining manufacturing precision even as component sizes decrease
Solution Approach 2:
The epitaxial growth process utilizes controlled parameters (temperature, pressure, gas flow) to achieve precise atomic-layer deposition. By changing and controlling these parameters, the process can reliably create smaller features with high precision, enabling increased functional density without sacrificing manufacturing quality
3Device complexity
If epitaxial growth is performed without a seed layer to simplify the process, then device complexity is reduced, but manufacturing precision deteriorates due to seam formation and voids
Solution Approach 1:
The seed layer serves as an intermediary that enables seamless epitaxial growth by providing a suitable crystal template. This intermediate step prevents seam formation and voids that would otherwise occur during direct epitaxial growth on the insulating layer, thereby maintaining high manufacturing precision
Solution Approach 2:
Forming the seed layer as a preliminary step creates a controlled surface for epitaxial growth. This advance preparation ensures uniform crystal orientation and continuous growth, eliminating defects while adding only a single process step that is justified by the significant improvement in layer quality
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 improves device performance and reliability by ensuring seamless epitaxial growth, which is critical for maintaining efficiency and reducing defects in scaled-down semiconductor devices.
Implementation Method 1
an epitaxial layer is then grown by using the seed layer as a seed
Data Source
AI summary
A method of forming a semiconductor device includes the following operations. A substrate is provided with a recess therein. An insulating layer is formed on a bottom of the recess. A seed layer is formed on the insulating layer. An epitaxial layer is grown in the recess from the seed layer.