Cyclic Epitaxial Deposition With Variable Wafer Rotation for Uniform Doping
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Solution Overview
Problem
Achieving uniform doping in epitaxial phosphorus-doped silicon deposition at low temperatures is challenging, leading to poor material uniformity, and existing processes compromise selectivity towards dielectrics during epitaxial growth.
Innovation Solution
A cyclical deposition process using a rotary actuator to rotate the substrate at different angular frequencies during deposition and etching steps, with a precursor and etchant exposure, to selectively form a layer on specific surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If epitaxial deposition is performed at lower temperatures to enable novel integration schemes, then device integration capability is improved, but within-wafer doping uniformity deteriorates
Solution Approach 1:
The patent employs a cyclical deposition process that alternates between deposition steps and etching steps. During deposition, material is deposited at low temperature; during etching, a portion of the deposited material is removed. This periodic cycling allows accumulation of uniformly doped material over multiple cycles while maintaining low deposition temperature for device integration compatibility.
Solution Approach 2:
The patent changes process parameters by varying the rotation speed of the substrate holder between deposition and etching steps. The substrate rotates at a first speed during deposition and a second speed during etching, optimizing material distribution and doping uniformity at each stage while maintaining overall low temperature operation.
2Manufacturing precision
If process conditions are adjusted to increase phosphorus incorporation uniformity, then doping uniformity is improved, but selectivity towards dielectrics deteriorates
Solution Approach 1:
The cyclical process alternates between deposition where phosphorus is incorporated and etching where non-selective deposition on dielectrics is removed. This periodic action allows phosphorus uniformity to be optimized during deposition while selectivity is restored through selective etching of dielectric surfaces between cycles.
Solution Approach 2:
The patent maintains continuous processing by cycling through deposition and etching steps without interrupting the overall process flow. This continuous cyclical action ensures phosphorus is consistently incorporated into the epitaxial layer while dielectric surfaces are continuously protected through the etching step that removes non-selective deposits.
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 cyclical process enhances within-wafer and process uniformity, improving selectivity and uniformity of epitaxial deposition.
Implementation Method 1
rotating the substrate support at a deposition angular frequency by means of the rotary actuator; wherein the etching step comprises providing etchant via the etchant line to the reaction chamber to expose the substrate to the etchant while rotating the substrate support at an etching angular frequency
Implementation Method 2
deposition step comprises providing precursor via the precursor line to the reaction chamber to expose the substrate to the precursor
Implementation Method 3
etching step comprises providing etchant via the etchant line to the reaction chamber to expose the substrate to the etchant
Implementation Method 4
epitaxial processes at temperatures less than 500° C. are required to enable various novel integration schemes
Data Source
AI summary
Material deposition apparatuses and related methods described. Presently described apparatuses and methods allow executing cyclical deposition-etch processes with varying substrate rotation speeds during deposition and etch steps. Thus, they allow depositing a material with excellent uniformity.