Semiconductor Substrate Planarization via Multi-Angle Ion Implantation
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Solution Overview
Problem
Conventional polishing processes for semiconductor substrates, such as chemical mechanical polishing (CMP) and ion bombardment, are inadequate in effectively reducing surface roughness and structuring, particularly for applications like Smart-Cut processes where surface roughness from fracturing needs to be minimized.
Innovation Solution
A process involving multiple ion implantations at varying orientations and energies to modify the upper substrate layer, followed by selective removal through thermal etching, which can amorphize or dope the substrate while retaining its single-crystal structure, thereby reducing surface roughness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional polishing processes (CMP or ion bombardment) are used to reduce surface roughness, then surface structures can be eliminated, but the processes are inadequate in effectively reducing surface roughness and structuring
Solution Approach 1:
The patent changes the fundamental parameters of the polishing process by using multiple ion implantations with varying orientations and energies, followed by selective removal. This transforms the conventional single-step mechanical/chemical polishing into a multi-step physical-chemical process that achieves superior surface roughness reduction and structuring control
Solution Approach 2:
The polishing process is segmented into distinct steps: multiple ion implantations with different orientations, modification of the upper substrate layer, and selective removal. This segmentation allows each step to be optimized independently, achieving cumulative improvement in surface quality that conventional single-step processes cannot attain
2Manufacturing precision
If multiple ion implantations are performed to modify the upper substrate layer, then surface roughness is reduced, but the process complexity increases
Solution Approach 1:
The multiple ion implantation process serves multiple functions simultaneously: it modifies the upper substrate layer, creates controlled damage patterns, and prepares the surface for selective removal. This multi-functionality consolidates what would otherwise require separate process steps into a unified implantation-modification-removal sequence
Solution Approach 2:
By systematically varying implantation parameters (orientation, energy, dose) across multiple steps, the process achieves complex surface modification through controlled parameter changes rather than complex equipment. The parameter variation creates the necessary structural differences for selective removal while maintaining process manageability
3Manufacturing precision
If selective removal is performed to eliminate the upper part, then surface structures are reduced, but control over remaining surface quality becomes critical
Solution Approach 1:
The ion implantation and material modification steps are performed as preliminary actions before selective removal. This preliminary modification creates distinct physical and chemical properties in the upper substrate layer, enabling selective removal while ensuring the remaining surface has the desired quality. The preliminary action prepares the surface for controlled removal rather than attempting to control removal in real-time
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 process effectively reduces the height, width, and pitch of surface structures, achieving smoother surfaces by replicating the upper face patterns conformally within the substrate material, allowing for precise control of implantation depth and angle to minimize roughness and maintain structural integrity.
Implementation Method 1
a) a step of multiple implantations of ions from an upper face of the substrate, so as to modify the material of an upper part of the substrate
Implementation Method 2
the method further comprises, after step a), a step of solid phase recrystallization of a lower part of said upper part of the substrate
Implementation Method 3
in step b), the selective removal of the upper part of the substrate is carried out by a thermal etching process using a gas mixture
Data Source
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AI summary
This description relates to a method for polishing a semiconductor substrate (100), comprising: a) a step of multiple ion implantation from an upper face (100U) of the substrate, so as to modify the material of an upper portion (100A) of the substrate, the multiple implantation step comprising several successive implantations under different respective implantation orientations; and b) a step of selective removal of the upper portion (100A) of the substrate.