SiGe:B to Si:B Deposition Transition for Defect-Free Interfaces
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Solution Overview
Problem
In semiconductor device fabrication, the incorporation of constituents with different affinities during material layer deposition can lead to within-layer concentration variations, particularly at the interface between layers, due to their competitive incorporation into the growing material layer, affecting the desired properties and structural integrity of the semiconductor structure.
Innovation Solution
A method involving the sequential deposition of boron-doped silicon germanium (SiGe:B) and boron-doped silicon (Si:B) layers, where the flow of precursors is managed to control the incorporation rates, specifically by ceasing the boron-containing precursor flow during SiGe:B deposition, decreasing the germanium-containing precursor flow, and increasing the silicon-containing precursor flow, followed by resuming the boron-containing precursor flow, to achieve a defect-free interface and controlled boron concentration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If constituents with different incorporation affinities are deposited simultaneously, then deposition efficiency is improved, but within-layer concentration variation occurs at the interface
Solution Approach 1:
The deposition process is segmented into distinct stages: first depositing the SiGe:B layer with controlled precursor flows, then transitioning to the Si:B layer by adjusting precursor flows. This segmentation prevents constituent competition at the interface by separating the deposition timelines of different material compositions.
Solution Approach 2:
The SiGe:B layer is deposited first as a preliminary layer before transitioning to the Si:B layer. By establishing the SiGe:B layer with controlled boron incorporation beforehand, the subsequent Si:B layer deposition can proceed without interface concentration variations, as the preliminary layer provides a stable foundation.
2Productivity
If precursor flow rates are increased to improve deposition speed, then productivity is improved, but constituent competition for incorporation intensifies
Solution Approach 1:
The precursor flow rates are dynamically adjusted during the deposition process. The boron-containing precursor flow is ceased during SiGe:B deposition and then resumed for Si:B layer deposition. The germanium-containing precursor flow is decreased and then ceased. The silicon-containing precursor flow is increased. These dynamic adjustments maintain optimal deposition speed while preventing constituent competition.
Solution Approach 2:
The process utilizes parameter changes in precursor flow rates to control constituent incorporation. By changing the flow rates of boron-containing, germanium-containing, and silicon-containing precursors at specific transition points, the method achieves both high deposition speed and precise control over constituent incorporation at the layer interface.
3Reliability
If purging is performed between layers to remove residual precursors, then contamination is reduced, but processing time increases
Solution Approach 1:
The deposition process maintains continuity by avoiding purging between layers. Instead of stopping to purge residual precursors, the method continuously adjusts precursor flows to transition from SiGe:B to Si:B layer deposition. This continuous action eliminates idle purging time while still achieving layer purity through controlled precursor management.
Solution Approach 2:
The precursor flows are adjusted in advance during the transition phase, preparing the reactor atmosphere for the next layer before actual deposition begins. This preliminary adjustment of boron-containing, germanium-containing, and silicon-containing precursor flows ensures that when the Si:B layer deposition starts, the atmosphere is already optimized, eliminating the need for time-consuming purging.
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 ensures a defect-free interface and controlled boron concentration between the SiGe:B and Si:B layers, reducing the risk of crystallographic slip defects and improving the electrical properties of the semiconductor structure by managing the competitive incorporation of constituents, thus enhancing the semiconductor device's performance and reliability.
Implementation Method 1
Material layer deposition is generally accomplished by supporting a substrate within a reactor, providing one or more precursors to the reactor, and exposing the substrate to the one or more precursor under conditions selected to cause a desired material layer to deposit onto the surface of the substrate
Data Source
AI summary
A method of making a semiconductor structure includes seating a substrate within a chamber arrangement, depositing a boron-doped silicon germanium layer onto the substrate, and depositing a boron-doped silicon layer onto the boron-doped silicon germanium layer. Deposition of the boron-doped silicon layer includes ceasing flow of a boron-containing precursor to the chamber arrangement; decreasing flow of a germanium-containing precursor to the chamber arrangement; increasing flow of a silicon-containing precursor to the chamber arrangement; ceasing, after increasing flow of the silicon-containing precursor, flow of the germanium-containing precursor to the chamber arrangement; and resuming flow of the boron-containing precursor to the chamber arrangement. Semiconductor structures as well as semiconductor processing systems and computer program products for making semiconductor structures are also described.