Selective Boron-Doped Germanium Formation on Silicon-Germanium
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for forming doped germanium on silicon-containing surfaces face challenges in achieving high mobility and selectivity, particularly as device geometries shrink, requiring improved techniques for boron or gallium doping to enhance transistor performance.
Innovation Solution
The method involves a pre-treatment process to clean the silicon-germanium surface, followed by selective deposition of a boron or gallium-doped layer using co-flowed germanium and boron source gases, and a post-treatment process to remove native oxides and contaminants, optimizing the doping process without high-temperature baking, which can lead to defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If high-temperature baking is used to form doped germanium, then dopant incorporation is enhanced, but Ge segregation and defects increase
Solution Approach 1:
The patent changes the temperature parameter from high-temperature baking to low-temperature processing (below 450°C), and modifies the deposition method from conventional CVD to selective epitaxial growth with co-flowed gases. This parameter change enables dopant incorporation without causing Ge segregation and defects
Solution Approach 2:
The patent introduces a sacrificial silicon-germanium layer as an intermediary between the silicon-containing surface and the doped germanium layer. This intermediary enables selective deposition on the silicon-germanium surface while preventing direct interaction that would cause defects, and is subsequently removed to reveal the doped germanium layer
2Area of stationary object
If conventional deposition methods are used, then coverage is achieved, but selectivity on silicon-containing surfaces is poor
Solution Approach 1:
The patent applies local quality by making the deposition process selective to specific surface regions. The sacrificial silicon-germanium layer is deposited only on silicon-containing surfaces, and subsequent etching removes it selectively, enabling doped germanium formation only where needed while leaving other areas unaffected
Solution Approach 2:
The patent performs preliminary action by depositing the sacrificial silicon-germanium layer before forming the doped germanium layer. This preliminary layer serves as a template that guides selective deposition and is later removed, ensuring precise spatial control over where doped germanium forms
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 results in high dopant incorporation and selectivity, improving the formation of doped germanium with reduced defects, enhancing the performance of p-type contact materials in advanced MOSFETs by maintaining a clean surface and avoiding Ge segregation.
Implementation Method 1
selectively depositing a boron-doped or a gallium-doped layer on the exposed silicon-germanium surface... co-flowing a germanium source gas and a boron source gas
Data Source
AI summary
Implementations described herein generally relate to methods and systems for depositing layer on substrates, and more specifically, to methods for forming boron or gallium-doped germanium on silicon-containing surfaces. In one implementation, a method of processing a substrate is provided. The method comprises exposing a substrate having an exposed silicon-germanium surface and an exposed dielectric surface to a pre-treatment process, selectively depositing a boron-doped or a gallium-doped layer on the exposed silicon-germanium surface and exposing the substrate to a post-treatment process.