Selective Atomic Layer Etching for Substrate Planarity
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Solution Overview
Problem
Current planarization techniques for substrates, such as CMP, can cause physical damage and are not effective in reducing height differentials between higher and lower regions of features on patterned substrates during IC fabrication.
Innovation Solution
A selective atomic layer etching (ALE) process in a spatial atomic layer processing system, where a patterned substrate is exposed to a precursor gas while rotating, preferentially forming a modified layer on higher regions, which is then removed to etch these regions, thereby reducing height differentials without physical damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If chemical mechanical polishing (CMP) is used for planarization, then substrate planarity is improved, but physical damage occurs to the substrate features
Solution Approach 1:
The patent replaces the mechanical CMP process with a chemical ALE process. Instead of using mechanical abrasion to remove material, the invention uses sequential chemical reactions: a precursor gas reacts with the oxide surface to form a modified layer, which is then removed by a second gas. This chemical approach achieves planarization without the physical damage inherent in mechanical polishing.
Solution Approach 2:
The patent changes the fundamental parameter of the planarization process from mechanical force to chemical reactivity. By controlling the chemical reactions in ALE cycles, the process selectively removes material based on chemical properties rather than mechanical contact, eliminating the harmful mechanical damage while maintaining planarity improvement.
2Length of stationary object
If conventional etching is used to reduce height differentials, then feature height is reduced, but lateral etching occurs reducing manufacturing precision
Solution Approach 1:
The patent segments the etching process into distinct sequential steps (ALE cycles) rather than using a single continuous etch. Each cycle consists of a modification step followed by a removal step, allowing precise control over which material is removed. This segmentation enables vertical selectivity while preventing lateral etching that would compromise feature dimensions.
Solution Approach 2:
The patent employs periodic ALE cycles where the substrate is repeatedly exposed to precursor gas and then etch gas in alternating sequences. This periodic action allows controlled, incremental removal of material from higher regions while maintaining the integrity of lower regions, achieving height differential reduction without lateral etching.
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 ALE process effectively reduces height differentials by up to 50% or more, achieving planarization without the damaging effects of conventional methods, and can be used as an alternative or in conjunction with CMP to improve substrate planarity.
Implementation Method 1
a surface of the substrate may be exposed to a reactive precursor, which adsorbs on and reacts with the surface material to produce a modified surface layer
Implementation Method 2
a surface of the substrate may be exposed to a reactive precursor, which adsorbs on and reacts with the surface material to produce a modified surface layer
Implementation Method 3
During the etch step, the surface of the substrate may be bombarded with ions to remove or etch the modified surface layer
Data Source
AI summary
Atomic layer processing systems are provided for planarizing a patterned substrate utilizing a rotating platen. An atomic layer processing system may include a spatial atomic layer processing chamber with the rotating platen, a sensor that provides sensor data related to a property of the patterned substrate and/or a reaction in the spatial atomic layer processing chamber, and a controller. The controller may be coupled to the sensor to receive the sensor data and utilize such data to adjust at least one operating parameter of the atomic layer processing system so as to achieve a desired amount of planarization of the patterned substrate.