Germanium Oxide Pre-Clean Module for Substrate Surface Preparation
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Solution Overview
Problem
The presence of native oxide layers on substrate surfaces during integrated circuit fabrication can introduce defects and adversely affect the electrical performance of material layers, particularly in silicon-germanium substrates, due to exposure to oxygen and residual oxidizing agents.
Innovation Solution
A pre-cleaning method involving the deposition of halogen-containing materials on the substrate surface, followed by sublimation to remove oxide layers, and the application of a chlorine-containing passivation film to protect the exposed silicon, ensuring a high-quality oxide-free surface for subsequent material deposition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning methods are used to remove oxide layers, then oxide removal is achieved, but substrate etching and contamination occur
Solution Approach 1:
The patent utilizes the phase transition of halogen-containing pre-clean material from solid to vapor through sublimation. The material is deposited as a solid film on the substrate surface, then heated to sublime and vaporize, carrying oxide contaminants away without etching the substrate. This phase transition mechanism enables selective oxide removal while preserving the substrate integrity.
Solution Approach 2:
The patent changes the physical and chemical parameters of the cleaning process by using halogen-containing materials with specific sublimation temperatures. By controlling the heating temperature to match the sublimation point of the pre-clean material rather than exceeding it, the process achieves oxide removal at lower temperatures that prevent substrate damage and contamination.
2Manufacturing precision
If high temperature processing is used to remove oxide layers, then oxide removal is effective, but substrate damage and defects increase
Solution Approach 1:
The process employs sublimation of the halogen-containing pre-clean material at controlled temperatures. The substrate is heated to a temperature sufficient to sublime the pre-clean material (which has a lower sublimation temperature) but below the threshold that would cause substrate damage or generate defects. This phase transition-based cleaning occurs at moderate temperatures that preserve substrate reliability.
3Manufacturing precision
If multiple cleaning steps are performed to ensure oxide-free surface, then cleaning thoroughness is improved, but process complexity and time increase
Solution Approach 1:
The patent combines multiple functions into a single integrated process step. The halogen-containing pre-clean material simultaneously reacts with and removes oxide layers, then sublimes to carry contaminants away, and leaves a protective halogen layer that prevents re-oxidation. This merged process achieves thorough cleaning in one operation rather than requiring multiple separate cleaning, heating, and protection steps.
Solution Approach 2:
The halogen-containing pre-clean material serves multiple functions: it chemically reacts with oxide layers for removal, acts as a sacrificial carrier that sublimes to transport contaminants, and forms a protective layer that prevents re-oxidation. This multi-functional material enables comprehensive surface preparation in a single process sequence, reducing overall process complexity.
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 process effectively removes oxide layers while minimizing contamination and re-oxidation, resulting in high-quality material layers with reduced defects and improved electrical performance.
Implementation Method 1
sublimating a portion of the halogen-containing pre-clean material to expose the silicon on the surface
Implementation Method 2
A passivation material can be deposited on the exposed silicon
Data Source
AI summary
In some embodiments, a method for integrated circuit fabrication includes removing oxide material from a surface of a substrate, where the surface includes silicon and germanium. Removing the oxide material includes depositing a halogen-containing pre-clean material on a silicon oxide-containing surface and sublimating a portion of the halogen-containing pre-clean material to expose the silicon on the surface. A passivation film is deposited on the exposed silicon. The passivation film may include chlorine. The passivation film may prevent contamination of the silicon surface by chemical species from the later sublimation, which may be at a higher temperature than the earlier sublimation. Subsequently, a remaining portion of the halogen-containing pre-clean material and the passivation film are sublimated. A target material, such as a conductive material, may subsequently be deposited on the substrate surface.