ALD Substrate Bias Control for Stable Precursor Impingement
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Solution Overview
Problem
In atomic layer deposition (ALD) processes, the impingement rate of precursors decreases due to surface area changes of solid precursors, leading to increased resistivity and impurity retention in thin films, which affects film quality and efficiency.
Innovation Solution
A deposition apparatus that applies electric field bias during the deposition process, utilizing a controller to manage precursor and reactant flows, and alternating positive and negative polarity sub-cycles to control precursor bonding and purging, thereby maintaining impingement rate and reducing activation energy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If solid precursor is used in ALD process, then the precursor can be supplied into the chamber, but the surface area of the solid precursor changes due to sublimation, causing the concentration of the precursor flowing into the chamber to change and the impingement rate to decrease
Solution Approach 1:
The patent applies electric field bias to the substrate, changing the electrical parameter of the substrate to enhance precursor attraction. By controlling the polarity of the electric field during different sub-cycles, the system maintains stable precursor impingement rate despite sublimation-induced concentration changes
Solution Approach 2:
The system pre-applies electric field bias to the substrate before precursor introduction. This preliminary action creates an electric field environment that prepares the substrate to attract and maintain stable precursor flux, compensating for upcoming concentration changes due to sublimation
2Productivity
If high activation energy is used in ALD process, then the deposition can proceed, but impurities contained in the precursor remain within the formed thin film, thus increasing the resistivity
Solution Approach 1:
The patent employs periodic alternation of electric field polarity between positive and negative sub-cycles. This periodic action enables systematic control of precursor deposition and byproduct removal, achieving thorough ligand exchange that reduces film resistivity while maintaining deposition productivity
Solution Approach 2:
The controller monitors and adjusts the electric field bias polarity based on the deposition cycle stage. This feedback control ensures optimal conditions for both deposition rate and impurity removal, achieving low resistivity films through controlled ligand exchange
Data Source
AI summary
An example deposition apparatus includes a chamber, a voltage generator, a precursor supplier, a reactant supplier, and a controller. The chamber is configured to accommodate a voltage applicator comprising a stage that accommodates a substrate. The voltage generator is electrically connected with the stage in order for bias voltage to be applied to the substrate. The precursor supplier is configured to supply precursor into the chamber. The reactant supplier is configured to supply reactant into the chamber. The controller is configured to control the bias voltage applied to the substrate, precursor flow, and reactant flow.