ALD Method Using UV Irradiation for Semiconductor Interface Quality
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Solution Overview
Problem
Atomic Layer Deposition (ALD) processes face challenges in achieving high interface quality between semiconductor substrates and deposited layers due to temperature sensitivity, particularly at conventional deposition temperatures where surface hydroxyl concentrations are limited, leading to poor electrical characteristics.
Innovation Solution
The method involves exposing a semiconductor substrate to ultraviolet (UV) irradiation during the ALD process, using precursor gases like hafnium chloride and water, and maintaining an inert atmosphere to enhance hydroxyl formation and improve layer deposition, especially at lower temperatures where surface hydroxyl concentrations are higher.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional ALD deposition is performed at 300°C, then the ALD reaction cycle can be driven to completion, but the surface hydroxyl concentration is limited leading to poor interface quality
Solution Approach 1:
The patent applies preliminary action by exposing the semiconductor substrate to UV irradiation before the ALD deposition step. This pre-treatment generates additional surface hydroxyl groups on the silicon substrate, ensuring high [OH] concentration is available when the deposition begins, thereby improving interface quality without compromising the completeness of the ALD reaction cycle
Solution Approach 2:
The patent changes the physical-chemical state of the substrate surface by introducing UV irradiation as an additional parameter. This energy input modifies the surface chemistry to increase hydroxyl concentration, allowing the process to maintain both high interface quality and complete reaction cycling at conventional temperatures
2Reliability
If lower temperature is used to increase surface hydroxyl concentration, then interface quality improves, but the ALD reaction cycle is not driven to completion
Solution Approach 1:
The UV irradiation step performed before deposition serves as preliminary action that pre-generates surface hydroxyls. This allows the subsequent deposition to proceed at lower temperatures while still having sufficient reactive sites, maintaining both interface quality and reaction completeness
Solution Approach 2:
UV irradiation acts as an intermediary that mediates between the conflicting requirements of low temperature (for high [OH]) and reaction completion. The UV energy input compensates for the lower thermal energy, enabling the ALD cycle to complete successfully while maintaining the benefits of low-temperature deposition
3Quantity of substance
If UV irradiation is applied during inert atmosphere step, then surface hydroxyl concentration increases, but process complexity increases
Solution Approach 1:
The patent merges the UV irradiation step with the existing inert atmosphere purging step. By combining these two operations into a single process stage, the patent avoids adding separate equipment or steps, thereby minimizing process complexity while still achieving the beneficial increase in surface hydroxyl concentration
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 significantly improves the chemical and electrical properties of the deposited layers by increasing density and reducing defects at the interface, resulting in superior electrical characteristics and reduced leakage performance.
Implementation Method 1
the semiconductor substrate is exposed to ultraviolet (UV) irradiation at least once during a step (d)
Implementation Method 2
providing a pulse of a first precursor gas into the reactor, providing a pulse of a second precursor gas into the reactor
Data Source
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AI summary
The invention is related to an ALD method for depositing a layer comprising the steps of: a) providing a semiconductor substrate in a reactor, b) providing a pulse of a first precursor gas into the reactor, c) providing a pulse of a second precursor gas into the reactor, d) providing an inert atmosphere in the reactor, e) repeating step b) through step d), wherein at least once during step d) the semiconductor substrate is exposed to UV irradiation.