Differential Heating of Nanostructures via Polarized Light
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Solution Overview
Problem
Challenges arise in semiconductor processing, particularly in heating steps for nano-scaled structures, as different materials like Si and Ge require distinct temperatures for dopant activation and recrystallization, making it difficult to use CMOS processes for substrates with both Si and Ge devices without compromising the integrity of one material by using the temperature required for the other.
Innovation Solution
A method involving the simultaneous exposure of non-parallel elongate nanostructures to polarized light of specific wavelength and polarization, allowing for differential heating of structures made from different materials, such as Si and Ge, by optimizing light absorption based on material and orientation, enabling separate temperature control for each structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If higher temperature is applied for Si dopant activation, then Si junction activation is improved, but Ge junction integrity deteriorates
Solution Approach 1:
The patent divides the heating process into separate spatial zones using a mask structure, allowing different temperatures to be applied to Si and Ge junctions simultaneously on the same wafer. The mask segments the light exposure so that Si regions receive higher temperature for activation while Ge regions receive lower temperature to preserve junction integrity.
Solution Approach 2:
The patent applies different thermal conditions to different locations on the wafer by using a mask with varying light transmission properties. Si-based junctions are exposed to higher temperatures while Ge-based junctions are exposed to lower temperatures, allowing each material type to receive locally optimized processing conditions.
2Reliability
If lower temperature is applied for Ge dopant activation, then Ge junction integrity is maintained, but Si junction activation deteriorates
Solution Approach 1:
The mask structure segments the wafer surface into regions with different light exposure, enabling Si junctions to receive sufficient temperature for proper dopant activation while Ge junctions receive limited exposure to maintain their structural integrity.
Solution Approach 2:
Different regions of the wafer are subjected to different thermal conditions through the mask, ensuring that Si-based structures receive the higher temperatures needed for activation while Ge-based structures are protected from excessive heating.
3Ease of manufacture
If single temperature heating is applied to accommodate one material, then that material's processing is optimized, but the other material's processing deteriorates
Solution Approach 1:
The patent uses a mask to segment the heating field, allowing a single heating step to simultaneously provide different effective temperatures to different material regions. This enables CMOS process compatibility by treating multiple material types in one step while maintaining the reliability of each device type through localized temperature 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
This method effectively activates dopants and recrystallizes nanostructures while maintaining the structural integrity of both Si and Ge junctions, allowing for the use of CMOS processes on substrates with both materials by achieving precise temperature control through differential light absorption.
Implementation Method 1
heating the elongate nanostructures, wherein the structures are heated to different temperatures by applying light having a wavelength and having a polarization such that a difference in absorption of light occurs in the first and second nanostructure
Data Source
AI summary
The present disclosure is related to a method of fabricating a semiconductor device involving the production of at least two non-parallel nano-scaled structures on a substrate. These structures are heated to different temperatures by exposing them simultaneously to polarized light having a wavelength and polarization such that a difference in absorption of light occurs in the first and second nanostructure. In some cases the light is polarized in a plane that is parallel to one of the structures. The present disclosure may provide differential heating of semiconductor structures of different materials, such as Ge and Si fins.