SiGe Deposition Using Multiple Precursors for Edge Uniformity
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Solution Overview
Problem
Existing gas-phase reactor systems face challenges in achieving uniform film thickness and composition, particularly at the edges of substrates, when forming silicon germanium layers, leading to variations in semiconductor devices.
Innovation Solution
The method involves providing multiple silicon precursors and a germanium precursor to the reaction chamber, with the option of a precoating layer on the chamber surfaces, allowing for controlled gas flow and deposition processes to enhance uniformity, using a system with a controller to manage precursor flow and deposition conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single silicon precursor is used in the deposition process, then the process is simple, but the uniformity of silicon germanium layer thickness and composition across the substrate is poor
Solution Approach 1:
The single silicon precursor is segmented into multiple precursors: a first silicon precursor (e.g., silane) and a second silicon precursor (e.g., dichlorosilane). Each precursor contributes differently to the deposition process, with the first precursor providing uniform baseline deposition and the second precursor enabling edge region control. This segmentation resolves the contradiction by improving uniformity through differentiated precursor functions while maintaining reasonable process complexity.
Solution Approach 2:
Different precursors are used to address different regions of the substrate: the first silicon precursor serves the central region with uniform deposition, while the second silicon precursor specifically targets the edge regions to correct thickness and composition variations. This local quality approach ensures that each region receives the appropriate precursor composition for optimal uniformity.
2Productivity
If gas flow rate is increased to improve deposition speed, then productivity increases, but uniformity of film properties across the substrate deteriorates
Solution Approach 1:
The gas flow rates of the first and second silicon precursors are dynamically adjusted during the deposition process. The first precursor flows at a higher rate for central region deposition, while the second precursor flow is modulated to provide enhanced silicon supply at edge regions. This dynamic flow control enables high overall deposition speed while maintaining uniformity across different substrate regions.
Solution Approach 2:
The deposition process uses periodic introduction of the first and second silicon precursors in a controlled sequence. The first precursor is introduced during phases requiring high deposition rate, while the second precursor is introduced during phases requiring uniformity control. This periodic action pattern allows the system to achieve both high productivity and uniform film properties.
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 significantly improved uniformity of silicon germanium layer thickness and composition across the substrate, including near the edges, reducing variability and enhancing die yield in semiconductor manufacturing.
Implementation Method 1
modifying the emission of thermal energy from surfaces within the reaction chamber
Implementation Method 2
Gas-phase reactors, such as chemical vapor deposition (CVD) reactors, can be used for a variety of applications, including depositing materials on a substrate surface
Data Source
AI summary
A method of forming a silicon germanium layer on a surface of a substrate and a system for forming a silicon germanium layer are disclosed. Examples of the disclosure provide a method that includes providing a plurality of growth precursors to control and/or promote parasitic gas-phase and surface reactions, such that greater control of the film (e.g., thickness and/or composition) uniformity can be realized.