Selective ALE Planarization of Patterned Substrates Without CMP Damage
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Solution Overview
Problem
Current planarization techniques in the fabrication of integrated circuits, such as chemical mechanical polishing (CMP), often result in physical damage and are not effective in reducing height differentials between higher and lower regions of patterned substrates, necessitating a more precise method for achieving substrate planarity.
Innovation Solution
A selective atomic layer etching (ALE) process is employed in a spatial atomic layer processing system, where a patterned substrate is rotated at varying speeds to preferentially form and remove a modified layer on higher regions, thereby reducing the height differential between features without physical damage, using precursor gases like trimethylaluminum and BCl3, and subsequent plasma removal steps.
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 on the substrate surface
Solution Approach 1:
The patent replaces the mechanical CMP process with a chemical-based selective ALE process using precursor gases (trimethylaluminum and BCl3) to form and remove modified layers, eliminating mechanical contact and associated physical damage while achieving planarity through controlled chemical reactions
Solution Approach 2:
The patent changes the planarization mechanism from mechanical removal to controlled chemical deposition and removal cycles, using parameter control (rotation speed, gas flow, temperature) to achieve selective etching of higher regions without damaging the substrate
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 method effectively decreases height differentials by up to 50% or more, providing a planarized substrate with reduced physical damage compared to conventional CMP techniques, and can be used as an alternative or in conjunction with CMP to enhance planarity.
Implementation Method 1
a surface of the patterned 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 patterned 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
Methods are provided for planarizing a patterned substrate in a spatial atomic layer processing system comprising a rotating platen. The patterned substrate may generally include features having higher regions and lower regions. To planarize the patterned substrate, or reduce a height differential between the higher and lower regions, a selective atomic layer etching (ALE) process is disclosed to preferentially form a modified layer on the higher regions of the features by exposing a surface of the patterned substrate to a precursor gas while the rotating platen spins at a high rotational speed. By preferentially forming the modified layer on the higher regions of the features, and subsequently removing the modified layer, the selective ALE process described herein preferentially etches the higher regions of the features to lessen the height differential between the higher and lower regions until a desired planarization of the features is achieved.