SiGe Epitaxial Layer Protection Against Germanium Migration
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Solution Overview
Problem
High germanium atom migration and agglomeration in silicon germanium epitaxial layers during high-temperature processes lead to surface unevenness and contamination from other atoms, affecting semiconductor device yield.
Innovation Solution
A pure silicon layer is formed on top of the silicon germanium epitaxial layer to prevent germanium atom migration and agglomeration, and a boron-doped silicon layer is added to protect the underlying epitaxial layer from further contamination, using specific temperature and gas process conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a silicon germanium epitaxial layer is formed with high germanium concentration to improve carrier mobility, then the transistor performance is enhanced, but germanium atoms migrate and agglomerate at high temperature causing surface unevenness
Solution Approach 1:
A pure silicon layer is introduced as an intermediary barrier between the silicon germanium epitaxial layer and the environment. This intermediate layer prevents germanium atoms from migrating and agglomerating on the surface, thereby maintaining surface uniformity while preserving the high germanium concentration needed for carrier mobility enhancement in the underlying SiGe layer.
2Ease of manufacture
If high-temperature processes are used to form contact structures on the epitaxial layer, then the contact structure is successfully formed, but atoms from the contact structure migrate into the epitaxial layer affecting device yield
Solution Approach 1:
The pure silicon layer serves as a protective intermediary that blocks atomic diffusion between the contact structure and the silicon germanium epitaxial layer during high-temperature processing. This prevents contamination and atom migration into the epitaxial layer, thereby maintaining device yield while allowing contact structure formation to proceed.
Solution Approach 2:
The pure silicon layer is formed in advance before the contact structure fabrication process. This preliminary protective layer is already in place to prevent atom migration during subsequent high-temperature steps, ensuring that the epitaxial layer remains uncontaminated throughout the manufacturing process.
3Manufacturing precision
If a pure silicon layer is added to prevent germanium atom migration, then surface uniformity is improved, but the process complexity increases
Solution Approach 1:
The pure silicon layer performs multiple functions simultaneously: it acts as a diffusion barrier to prevent germanium atom migration, provides surface protection during subsequent processing, and serves as a template for forming contact structures. By consolidating these multiple functions into a single layer, the added complexity is minimized while achieving multiple protective effects.
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
The method effectively blocks germanium and boron atom migration, reduces surface unevenness, and protects the silicon germanium epitaxial layer from damage, enhancing semiconductor device quality and yield.
Implementation Method 1
the pure silicon layer can avoid the agglomeration and migration of the germanium atoms in the silicon germanium epitaxial layer
Implementation Method 2
forming a silicon germanium epitaxial layer in the substrate, forming a first silicon layer on the silicon germanium epitaxial layer
Data Source
AI summary
The invention provides a semiconductor manufacturing method, which comprises providing a substrate, forming a silicon germanium epitaxial layer in the substrate, forming a first silicon layer on the silicon germanium epitaxial layer, wherein the first silicon layer is a pure silicon layer, and forming a second silicon layer on the first silicon layer, wherein the second silicon layer comprises a silicon layer doped with boron atoms.