SiGe Regeneration Layer Reduces PMOS External Resistance
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Solution Overview
Problem
High external resistance due to boron-deficient regions in PMOS semiconductor devices formed using embedded SiGe processes, which degrades device performance.
Innovation Solution
A method involving the formation of a SiGe regeneration layer with a higher boron concentration than the SiGe seed layer or bulk SiGe, achieved by etching a portion of the SiGe seed layer and boron-doped bulk SiGe in a Sigma-shaped recess and epitaxially growing a boron-doped SiGe regeneration layer using RPCVD, allowing easier boron diffusion and reducing external resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If high concentration of Ge is used in boron-doped bulk SiGe to achieve high carrier mobility, then carrier mobility is improved, but external resistance increases due to boron-deficient regions
Solution Approach 1:
The patent applies local quality by creating a boron-doped SiGe regeneration layer with higher boron concentration specifically in the recess region where boron deficiency occurs. This localized high-boron region compensates for the boron-deficient areas caused by high Ge concentration in the bulk SiGe, thereby reducing external resistance while maintaining high carrier mobility in the channel region.
Solution Approach 2:
The patent uses preliminary action by forming the boron-doped SiGe regeneration layer in advance before final device operation. The regeneration layer is created by etching the recess and filling it with boron-doped SiGe material, which pre-compensates for boron deficiency and prevents high external resistance from developing during device operation.
2Strength
If high Ge concentration is used in bulk SiGe, then compressive stress and carrier mobility are improved, but boron diffusion is impeded resulting in boron-deficient regions
Solution Approach 1:
The patent addresses boron distribution stability by creating a localized high-boron concentration region in the SiGe regeneration layer. This local quality enhancement ensures adequate boron supply in the recess area where high Ge concentration would otherwise impede boron diffusion, maintaining stable boron distribution throughout the device structure.
Solution Approach 2:
The patent uses composite materials by combining SiGe bulk layer with a boron-doped SiGe regeneration layer. This composite structure allows the bulk SiGe to provide high Ge concentration for compressive stress and carrier mobility, while the regeneration layer provides high boron concentration to ensure adequate boron distribution, thus resolving the contradiction between these two requirements.
3Strength
If boron-doped bulk SiGe fills the Sigma-shaped recess, then compressive stress is increased, but external resistance increases due to boron deficiency in SiGe seed layer
Solution Approach 1:
The patent applies local quality by forming a boron-doped SiGe regeneration layer specifically in the recess region where boron deficiency occurs. This localized high-boron concentration compensates for the boron-deficient SiGe seed layer areas, reducing external resistance while maintaining the high compressive stress provided by the bulk SiGe filling the Sigma-shaped recess.
Solution Approach 2:
The boron-doped SiGe regeneration layer acts as an intermediary between the boron-deficient SiGe seed layer and the boron-doped bulk SiGe. It serves as a boron reservoir that can supply boron to adjacent regions, thereby reducing external resistance while allowing the bulk SiGe to maintain high compressive stress.
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 reduces external resistance and improves semiconductor device performance by ensuring adequate boron distribution, regardless of Ge concentration in the SiGe seed and bulk layers.
Implementation Method 1
a high concentration of Ge in the boron-doped bulk SiGe 105 may be necessary. However, a high concentration of Ge can impede boron atoms in the boron-doped bulk SiGe 105 from diffusing
Implementation Method 2
epitaxially growing a boron-doped SiGe regeneration layer using RPCVD
Implementation Method 3
forming a first recess by etching a portion of the SiGe seed layer and the boron-doped bulk SiGe in the Sigma-shaped recess
Data Source
AI summary
A semiconductor device is disclosed. The device includes a plurality of gates formed on a surface of a substrate, a plurality of sidewalls formed on side surfaces of the gates, a Sigma-shaped recess formed in the substrate between adjacent gates, a SiGe seed layer formed on an inner surface of the Sigma-shaped recess, boron-doped bulk SiGe formed on a surface of the SiGe seed layer, with the boron-doped bulk SiGe filling the Sigma-shaped recess, and a boron-doped SiGe regeneration layer formed in a first recess beneath the surface of the substrate. The first recess is formed by etching a portion of the SiGe seed layer and the boron-doped bulk SiGe in the Sigma-shaped recess, and the boron-doped SiGe regeneration layer has a higher concentration of boron than the SiGe seed layer or the boron-doped bulk SiGe.