Semiconductor Device Buffer Patterns Lattice Mismatch
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Solution Overview
Problem
As transistor size decreases, charge scattering in the channel increases, leading to a decrease in charge mobility, which impedes the improvement of transistor saturation current in semiconductor devices.
Innovation Solution
A semiconductor device is designed with a substrate having a compound semiconductor layer, including a first region with a germanium channel layer and a second region with a Group III-V semiconductor channel layer, utilizing buffer patterns and capping patterns to manage lattice mismatch and stress, thereby improving crystal quality and mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If transistor size is decreased to improve integration density, then device miniaturization is achieved, but charge mobility decreases due to increased scattering
Solution Approach 1:
The patent applies local quality by using different semiconductor materials for different regions: element semiconductor (e.g., Si, Ge) for P-type transistors and Group III-V semiconductor (e.g., GaAs, InP) for N-type transistors. This regional differentiation allows optimization of charge mobility for each transistor type while maintaining miniaturization benefits.
Solution Approach 2:
The patent employs composite material structures with multiple buffer layers containing different materials (element semiconductor and compound semiconductor layers) to manage lattice mismatch and stress. This composite approach enables the use of high-mobility Group III-V materials while maintaining crystal quality through carefully engineered buffer structures.
2Reliability
If Group III-V semiconductor material is used to improve charge mobility, then saturation current increases, but lattice mismatch with silicon substrate increases
Solution Approach 1:
The patent segments the buffer structure into multiple distinct layers: a first buffer layer with element semiconductor, a second buffer layer with compound semiconductor, and intermediate layers. This segmentation allows gradual transition from silicon substrate to Group III-V channel, managing lattice mismatch through staged composition changes.
Solution Approach 2:
The patent introduces intermediate buffer layers as mediators between the silicon substrate and Group III-V semiconductor channel. These intermediate layers (containing SiGe, SiSbC, or other compound semiconductors) gradually bridge the lattice constant difference, reducing dislocation density while enabling high-mobility channel formation.
3Manufacturing precision
If buffer patterns are added to manage lattice mismatch, then crystal quality improves, but device structure complexity increases
Solution Approach 1:
The buffer layer structure serves multiple functions simultaneously: it manages lattice mismatch, controls stress distribution, and provides a foundation for high-quality epitaxial growth. This multi-functionality reduces the need for additional separate structures, offsetting the apparent complexity increase with functional consolidation.
Data Source
AI summary
A semiconductor device includes a substrate, a compound semiconductor layer, and first and second semiconductor patterns. The substrate includes first and second regions. The first semiconductor pattern is on the compound semiconductor layer of the first region and includes an element semiconductor. The second semiconductor pattern is on the compound semiconductor layer of the second region and includes a Group III-V semiconductor material.