Near-Surface Work Function Tuning With Low-Temperature Doping
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Solution Overview
Problem
High-temperature bulk processing for work function alteration in semiconductor structures often damages surrounding devices and creates charge gradients, reducing performance and available area for other device layers.
Innovation Solution
The method involves growing an epitaxial layer and performing a dopant diffusion process at low temperatures (less than 450 degrees Celsius) to form a homogeneous passivation region with P-type or N-type dopants, creating an abrupt junction profile and adjusting the work function, while using a dry oxide process for controlled oxidation and selective removal to repair surface damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-temperature bulk processing is used to alter work function, then work function is modified, but surrounding devices are damaged and charge gradients are formed reducing performance
Solution Approach 1:
The patent changes the temperature parameter from high-temperature bulk processing to low-temperature (less than 450°C) near-surface processing. This parameter change enables work function modification while avoiding thermal damage to surrounding devices and preventing large charge gradients that reduce device performance.
Solution Approach 2:
The patent transitions from bulk processing to near-surface processing, concentrating the work function modification in a localized region (within approximately 5 nanometers of the surface). This local quality approach modifies the work function where needed while leaving the bulk material and surrounding devices unaffected, thereby maintaining device reliability.
2Manufacturing precision
If high-temperature bulk processing is used, then work function is altered, but large charge gradients are formed reducing available area for other device layers
Solution Approach 1:
By changing the temperature parameter to low-temperature processing (less than 450°C), the patent confines charge modification to a thin near-surface region rather than creating large charge gradients that extend through the bulk. This preserves more area for other device layers while still achieving the desired work function alteration.
Solution Approach 2:
The patent applies work function modification locally within approximately 5 nanometers of the surface, rather than creating extensive charge gradients throughout the bulk material. This localized approach maintains more available area for subsequent device layers while achieving the necessary work function change for device operation.
3Reliability
If low-temperature dopant diffusion is used, then thermal damage is prevented, but dopant embedding efficiency must be optimized
Solution Approach 1:
The patent optimizes dopant embedding at low temperatures (less than 450°C) by adjusting process parameters such as dopant concentration, diffusion time, and ambient conditions. This enables sufficient dopant embedding efficiency while maintaining the thermal advantages of low-temperature processing, preventing damage to surrounding devices and existing structures.
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 enhances charge manipulation capabilities, increases performance, and prevents thermal damage to existing structures, allowing for high-aspect-ratio trench processing without crystal damage, thereby improving semiconductor device efficiency.
Implementation Method 1
growing an epitaxial layer on surfaces of the structure to form a homogeneous passivation region
Implementation Method 2
performing a dopant diffusion process to further embed the dopants into surfaces of the structure
Implementation Method 3
forming an oxide layer on surfaces of the structure with a dry oxide process
Data Source
AI summary
Methods for adjusting a work function of a structure in a substrate leverage near surface doping. In some embodiments, a method for adjusting a work function of a structure in a substrate may include growing an epitaxial layer on surfaces of the structure to form a homogeneous passivation region as part of a substrate material of the substrate and performing a dopant diffusion process to further embed the dopants into surfaces of the structure to adjust a work function of the structure, wherein the dopant diffusion process is performed at less than approximately 450 degrees Celsius.