SiGe Epitaxial Growth on Oxide-Containing Substrates
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Solution Overview
Problem
Existing methods for epitaxially growing SiGe crystals on Si-based substrates often result in uneven crystal surfaces and poor crystal quality due to oxygen impurities from oxide films, especially when the area covered by the oxide film exceeds 50%, affecting the lattice matching and defect formation in the crystal films.
Innovation Solution
A method involving a halogen-containing gas flowing step followed by a source gas flowing step to grow Si-containing or Ge-containing crystal films, where the halogen-containing gas, such as dichlorosilane, is used to expose the substrate and prevent oxygen impurities from mixing with the growing crystal film, ensuring a smooth surface and improved crystal quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a SiGe crystal is epitaxially grown on a Si-based substrate with an oxide film, then carrier mobility is improved through compressive stress, but oxygen impurities from the oxide film contaminate the crystal and cause surface unevenness and poor crystal quality
Solution Approach 1:
The patent applies preliminary action by performing a halogen gas treatment step before the actual SiGe epitaxial growth. This pre-treatment modifies the oxide film surface to reduce oxygen outgassing during subsequent growth, thereby preventing oxygen contamination while maintaining the compressive stress effect for carrier mobility enhancement
Solution Approach 2:
The patent introduces a halogen gas (such as HCl or Cl2) as an intermediary substance that mediates between the oxide film and the SiGe crystal growth process. The halogen gas reacts with the oxide film to form volatile halide compounds, effectively removing oxygen sources before crystal growth begins, thus preventing oxygen incorporation into the crystal lattice
2Reliability
If the area covered by the oxide film exceeds 50%, then more compressive stress is generated to improve carrier mobility, but oxygen impurity contamination and crystal surface unevenness increase significantly
Solution Approach 1:
The patent performs halogen gas treatment before SiGe growth to pre-modify the oxide film surface. This preliminary action reduces oxygen outgassing during subsequent growth, enabling the process to handle large oxide film areas (exceeding 50% coverage) without significant oxygen contamination or surface unevenness
Solution Approach 2:
The patent changes the chemical state of the oxide film surface through halogen gas treatment, transforming it from an oxygen-rich surface that outgasses during growth to a halogen-modified surface that is more stable and less prone to oxygen release. This parameter change enables processing of large oxide coverage areas while maintaining crystal quality
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 enables the formation of Si-containing or Ge-containing crystal films with smooth surfaces and excellent crystal quality, even at lower temperatures, while reducing oxygen contamination and metal impurities, thereby enhancing deposition rates and film quality.
Implementation Method 1
exposing a surface of a semiconductor substrate to a halogen-containing gas that contains at least one of Si and Ge... thereby epitaxially growing a crystal film containing at least one of Si and Ge on the surface
Implementation Method 2
epitaxially growing a crystal film containing at least one of Si and Ge on the surface
Data Source
AI summary
A method of fabricating a semiconductor device according to one embodiment includes: exposing a surface of a semiconductor substrate to a halogen-containing gas that contains at least one of Si and Ge, the semiconductor substrate being provided with a member comprising an oxide and consisting mainly of Si; and exposing the surface of the semiconductor substrate to an atmosphere containing at least one of a Si-containing gas not containing halogen and a Ge-containing gas not containing halogen after starting exposure of the surface of the semiconductor substrate to the halogen-containing gas, thereby epitaxially growing a crystal film containing at least one of Si and Ge on the surface.