SOI Substrate Diode Implantation via Buried Layer Removal
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Solution Overview
Problem
The formation of substrate diodes in SOI devices for thermal sensing applications faces challenges due to high energy implantation processes, which result in reduced diode ideality and increased process variability, affecting the accuracy and reliability of thermal measurements.
Innovation Solution
The method involves removing material prior to the implantation process for forming a well region in the substrate diode, allowing for the use of reduced implantation energies and single-ionized dopant species, thereby reducing process variability and increasing throughput while maintaining compatibility with conventional process regimes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high energy implantation process is used to form substrate diode well region, then implantation depth and dopant concentration are achieved, but diode ideality is reduced and process variability increases
Solution Approach 1:
The patent applies preliminary action by removing the buried insulating layer before performing the implantation process. This preparatory step creates a direct path to the substrate semiconductor layer, allowing low-energy implantation to achieve the required dopant depth without requiring high energy. The layer removal is performed in advance to enable the subsequent low-energy implantation that preserves diode ideality.
Solution Approach 2:
The patent changes the implantation energy parameter from high to low by modifying the process conditions. Specifically, it uses implantation energies between 1 keV and 100 keV (preferably 10 keV to 50 keV) instead of conventional high energies. This parameter change, enabled by the preliminary layer removal, achieves the desired dopant distribution while maintaining diode ideality and reducing process variability.
2Productivity
If high energy implantation is used, then dopant distribution is achieved, but process variability and time are increased
Solution Approach 1:
By removing the buried insulating layer before implantation, the process enables low-energy implantation conditions that are more controllable and less variable. This preliminary action eliminates the need for high-energy processes that inherently introduce more variability and require longer processing times, thereby improving both reliability and productivity.
Solution Approach 2:
The patent changes the implantation energy parameter to a lower range (1-100 keV), which fundamentally alters the implantation dynamics. Lower energy implantation reduces scattering effects and process variability, while also decreasing the time required for achieving the desired dopant distribution, thus improving both process reliability and throughput.
3Manufacturing precision
If material is removed to enable reduced implantation energy, then diode characteristics are improved, but additional process steps are required
Solution Approach 1:
The patent merges the substrate diode formation process with the existing trench isolation process. Both processes require opening through the buried insulating layer, so these operations are combined into a single etching step that creates both the substrate diode opening and the trench isolation structures simultaneously. This integration reduces the total number of separate process steps while maintaining the benefits of low-energy implantation for improved diode characteristics.
Solution Approach 2:
The opening process through the buried insulating layer serves multiple functions: it creates access for the substrate diode implantation and simultaneously forms the trench isolation structures. This multi-functional approach eliminates the need for separate opening steps, reducing process complexity while enabling the low-energy implantation that improves diode characteristic accuracy.
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 diode stability and throughput, leading to more precise and reliable thermal measurement data by minimizing implantation-induced fluctuations and maintaining the integrity of the diode characteristics.
Implementation Method 1
implanting a dopant species through the first opening into the substrate semiconductor layer
Data Source
AI summary
By removing material during the formation of trench openings of isolation structures in an SOI device, the subsequent implantation process for defining the well region for a substrate diode may be performed on the basis of moderately low implantation energies, thereby increasing process uniformity and significantly reducing cycle time of the implantation process. Thus, enhanced reliability and stability of the substrate diode may be accomplished while also providing a high degree of compatibility with conventional manufacturing techniques.