Implant Isolation Region Alignment in Semiconductor Devices
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Solution Overview
Problem
The challenge in semiconductor manufacturing is the difficulty in accurately forming implant isolation regions, which can lead to misalignment of gate electrodes and the formation of parasitic transistors, affecting the performance of integrated circuit devices by increasing threshold voltage and power consumption.
Innovation Solution
The implementation of an end cap dielectric layer between the gate electrode and the implant isolation region, along with a self-aligned hardmask and implantation process, reduces the likelihood of forming a parasitic transistor by ensuring precise alignment and reducing the critical dimensions of the implant isolation region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If implant isolation regions are formed by well implantation, then damage to silicon surfaces is eliminated, but misalignment of gate electrodes with implant isolation regions occurs
Solution Approach 1:
The patent forms the implant isolation region before forming the gate electrode, establishing a self-aligned structure where the isolation region is created in advance to guide subsequent gate electrode formation. This preliminary action ensures that the gate electrode automatically aligns with the isolation region, eliminating misalignment issues while maintaining the benefit of reduced silicon surface damage.
Solution Approach 2:
The patent introduces an intermediary process step where the implant isolation region serves as a reference structure that mediates the alignment between different components. By forming the isolation region first and using it as a template, the gate electrode formation process automatically achieves precise alignment without requiring additional alignment steps, thus resolving the contradiction between eliminating surface damage and maintaining manufacturing precision.
2Reliability
If gate electrodes are misaligned to implant isolation regions, then leakage paths form between source and drain regions, but adding alignment steps increases process complexity
Solution Approach 1:
The patent implements a self-aligned fabrication process where the implant isolation region automatically serves as the alignment reference for gate electrode formation. The process is designed so that the gate electrode formation step inherently aligns with the isolation region without requiring external alignment adjustments or additional complex steps. This self-service mechanism ensures reliable device isolation while keeping the fabrication process simple and efficient.
3Manufacturing precision
If implant isolation regions are formed with larger dimensions, then alignment tolerance is increased, but parasitic transistor formation is more likely under high voltage
Solution Approach 1:
The patent optimizes the dimensional parameters of the implant isolation region to achieve a balance between alignment tolerance and parasitic transistor prevention. By carefully controlling the width and depth parameters of the isolation region during the implantation process, the design provides sufficient alignment tolerance for manufacturing variations while maintaining dimensions that prevent parasitic transistor formation under high voltage conditions. This parameter optimization resolves the contradiction between the two competing requirements.
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 the accuracy of implant isolation region formation, reduces parasitic transistor formation, and increases the effective channel width, thereby improving the performance and reducing power consumption of semiconductor devices.
Implementation Method 1
The implant isolation regions are formed by implanting an impurity to portions of a substrate
Data Source
AI summary
A device includes a semiconductor substrate and implant isolation region extending from a top surface of the semiconductor substrate into the semiconductor substrate surrounding an active region. A gate dielectric is disposed over an active region of the semiconductor substrate, wherein the gate dielectric extends over the implant isolation region. A gate electrode is disposed over the gate dielectric and an end cap dielectric layer is between the gate dielectric and the gate electrode over the implant isolation region.