Semiconductor Annealing for Shallow Diffused Layers
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Solution Overview
Problem
Conventional rapid thermal annealing methods, such as halogen lamp RTA, struggle to form low-resistant, shallow impurity diffused layers due to impurity ion diffusion, and ultra-short time annealing methods like flash lamp and laser annealing may not adequately fix crystal defects, leading to junction leakage issues.
Innovation Solution
A method combining microwave annealing to fix crystal defects at lower temperatures (up to 600°C) followed by flash lamp or laser annealing to activate impurity ions, thereby forming low-resistant, shallow impurity diffused layers while restraining impurity diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional RTA using halogen lamp is used, then annealing can be performed, but impurity ions diffuse significantly making it difficult to form shallow diffused layers
Solution Approach 1:
The annealing process is segmented into two distinct stages: first, flash lamp annealing for ultra-short duration (10-1000 μs) to activate impurity ions with minimal diffusion, then Spike RTA for longer duration to repair crystal defects. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The flash lamp annealing is performed as a preliminary action before Spike RTA. This preliminary ultra-short annealing activates the impurity ions and establishes the shallow diffused layer profile, which is then preserved during the subsequent Spike RTA that focuses on defect repair rather than further impurity activation.
2Manufacturing precision
If annealing temperature is lowered to restrain impurity ion diffusion, then shallow diffused layer can be formed, but impurity activation is insufficient increasing electrical resistance
Solution Approach 1:
The invention uses dynamic control of annealing temperature over time, employing an ultra-short high-temperature pulse from the flash lamp to achieve sufficient impurity activation, followed by a lower temperature Spike RTA phase. This dynamic temperature profile allows the system to achieve both shallow depth control and adequate impurity activation that would be impossible at any single fixed temperature.
3Manufacturing precision
If ultra-short time annealing (MSA) is used, then impurity ion diffusion is restrained and activation is improved, but crystal defects are not sufficiently fixed causing junction leakage
Solution Approach 1:
The annealing process is segmented into two distinct stages: first, flash lamp annealing for ultra-short duration (10-1000 μs) to activate impurity ions with minimal diffusion, then Spike RTA for longer duration to repair crystal defects. This segmentation allows each stage to optimize for its specific function without compromising the other.
Solution Approach 2:
The invention changes the time parameter of the annealing process, using ultra-short duration (10-1000 μs) for the flash lamp annealing to achieve impurity activation with minimal diffusion, then transitions to longer duration Spike RTA for defect repair. This parameter change in time allows the system to achieve both shallow depth control and adequate defect repair.
4Reliability
If Spike RTA is used to fix crystal defects, then defects are repaired, but high temperature causes significant impurity ion diffusion
Solution Approach 1:
The flash lamp annealing is performed as a preliminary action before Spike RTA. This preliminary ultra-short annealing activates the impurity ions and establishes the shallow diffused layer profile, which is then preserved during the subsequent Spike RTA that focuses on defect repair rather than further impurity activation.
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 effectively fixes crystal defects and activates impurity ions without significant diffusion, enabling the formation of low-resistant, shallow impurity diffused layers with improved semiconductor device performance and reduced junction leakage.
Implementation Method 1
a method using microwave irradiation to heat a semiconductor substrate
Implementation Method 2
an annealing method using a flash lamp filled with a noble gas, such as xenon (Xe) (hereafter, the method will be referred to as the flash lamp annealing)
Implementation Method 3
an annealing method using a CO2 laser or the like (hereafter, the method will be referred to as the laser annealing)
Implementation Method 4
impurity ions (e.g., boron (B) ions, phosphorus (P) ions, arsenic (As) ions, or the like) implanted into a semiconductor substrate
Data Source
AI summary
An ion implantation is performed to implant ions into a silicon substrate, and a microwave irradiation is performed to irradiate the silicon substrate with microwaves after the ion implantation. After the microwave irradiation, the silicon substrate is transferred to a heat-treatment apparatus, where the silicon substrate is treated with heat by being irradiated with light having a pulse width ranging from 0.1 milliseconds to 100 milliseconds, both inclusive.