Semiconductor Junction Leakage Reduction via Segmented SPER
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Solution Overview
Problem
Semiconductor devices produced using solid phase epitaxial regrowth techniques suffer from higher leakage current due to incomplete removal of post-implantation damage and increased band-to-band leakage current, especially at low temperatures.
Innovation Solution
A method involving the creation of a semiconductor substrate with two shallow areas: a surface area with a higher doping level and a second area with a lower doping level, achieved by partial solid phase epitaxial regrowth of an amorphous layer with specific dopant implantations and regrowth processes, reducing leakage current through controlled dopant activation and conductivity profiles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If solid phase epitaxial regrowth is used to form shallow junctions with good dopant activation and abruptness, then junction abruptness and dopant activation are improved, but leakage current increases due to incomplete damage removal and band-to-band leakage
Solution Approach 1:
The patent divides the doped region into two distinct areas: a first area (6-12 nm thick) adjacent to the surface with lower doping concentration, and a second area (2-4 nm thick) adjacent to the first area with higher doping concentration. This segmentation creates a graded junction structure that reduces band-to-band leakage while maintaining the abruptness benefits of SPER through the high-doping second area.
Solution Approach 2:
The patent applies different doping concentrations to different regions: the first area near the surface has lower doping to reduce leakage, while the second area deeper in the substrate has higher doping for strong activation and abruptness. This local quality variation optimizes both leakage reduction and junction characteristics in their respective regions.
2Temperature
If low temperature processing is used for metal gate and junction formation, then thermal budget is reduced, but post-implantation damage is not completely removed leading to higher leakage
Solution Approach 1:
The patent performs dopant implantation into the amorphous layer before regrowth, creating a doping profile that will be activated during the subsequent solid phase epitaxial regrowth process. This preliminary doping action allows for controlled dopant placement and activation at low temperatures, achieving good activation without requiring high temperature annealing that would remove damage.
Solution Approach 2:
The patent changes the physical state of the silicon layer from amorphous to crystalline through solid phase epitaxial regrowth at low temperatures (550-750°C). This phase change activates the dopants and repairs the amorphous structure without requiring high temperature processing, thereby reducing thermal budget while maintaining junction quality.
3Device complexity
If a single doping profile is used in shallow junctions, then process complexity is reduced, but leakage current cannot be efficiently controlled
Solution Approach 1:
The patent segments the doped region into two areas with different doping concentrations. The first area (6-12 nm) has lower doping profile and the second area (2-4 nm) has higher doping profile. This segmentation is achieved through sequential implantation steps: first implanting dopant to create the first amorphous layer with first doping profile, then implanting additional dopant to create the second amorphous layer with higher second doping profile, followed by selective regrowth.
Solution Approach 2:
The patent applies partial solid phase epitaxial regrowth to the first amorphous layer to form the second amorphous layer with higher doping concentration at a shallower depth. This partial regrowth action creates the graded structure needed for leakage reduction without requiring complete regrowth of all damaged regions, optimizing the balance between damage removal and leakage control.
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 leakage current by creating a semiconductor device with optimized dopant profiles and conductivity, allowing for better control over transistor performance and reduced leakage across junctions.
Implementation Method 1
heavy ions are implanted into a silicon substrate. The implanted heavy ions create an amorphous layer at the top surface of the substrate
Implementation Method 2
applying a first solid phase epitaxial regrowth action to partially regrow the first amorphous layer
Implementation Method 3
applying a first solid phase epitaxial regrowth action to partially regrow the first amorphous layer and form a second amorphous layer
Implementation Method 4
a silicon implanting step is performed to create an excess of vacancies compared to interstitials within a top layer of the substrate
Data Source
AI summary
Method of producing a semiconductor device, comprising: a) providing a semiconductor substrate, b) making a first amorphous layer in a top layer of the semiconductor substrate by a suitable implant, the first amorphous layer having a first depth, c) implanting a first dopant into the semiconductor substrate to provide the first amorphous layer with a first doping profile, d) applying a first solid phase epitaxial regrowth action to partially regrow the first amorphous layer and form a second amorphous layer having a second depth that is less than the first depth and activate the first dopant, e) implanting a second dopant into the semiconductor substrate to provide the second amorphous layer with a second doping profile with a higher doping concentration than the first doping profile, f) applying a second solid phase epitaxial regrowth action to regrow the second amorphous layer and activate the second dopant.