Silicon Carbide Wafer Splitting With Bowing Mitigation Layers
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Solution Overview
Problem
Wafer splitting from crystalline substrates like silicon carbide leads to bowing, complicating subsequent process integration steps.
Innovation Solution
Implant cleaving ions at one depth to create a separation layer and non-cleaving ions at another depth to form a mitigation layer, followed by thermal energy application to separate the wafer along the separation layer while the mitigation layer counters the bowing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wafer splitting is performed to increase device yield from a single substrate, then productivity is improved, but manufacturing precision deteriorates due to wafer bowing
Solution Approach 1:
The patent applies preliminary anti-action by implanting ions at a first depth to create a separation layer that will enable future wafer splitting, and simultaneously implanting ions at a second depth to create a bowing mitigation layer that pre-counters the bowing that will occur during splitting. This advance preparation allows the wafer to be split while maintaining flatness, resolving the contradiction between productivity improvement through splitting and manufacturing precision degradation from bowing.
2Loss of substance
If multiple wafers are split from a single crystalline substrate to reduce manufacturing cost, then loss of substance is reduced, but device complexity increases due to bowing complications in subsequent processing
Solution Approach 1:
The patent preemptively addresses the complexity issue by creating a bowing mitigation layer through ion implantation at a second depth before the wafer splitting process. This layer pre-counters the bowing that would otherwise complicate subsequent process integration steps, allowing multiple wafers to be successfully split from a single substrate without introducing excessive processing complexity.
3Ease of manufacture
If ion implantation is performed to create a separation layer for wafer splitting, then ease of manufacture is improved, but the crystalline substrate experiences bowing that reduces manufacturing precision
Solution Approach 1:
The patent applies local quality by performing differentiated ion implantation at two distinct depths: a first implantation at a first depth creates a separation layer with specific properties for easy wafer splitting, while a second implantation at a second depth creates a bowing mitigation layer with properties to counteract bowing. This localized differentiation of material properties at different depths enables both easy manufacture through splitting and maintenance of manufacturing precision.
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
Reduces wafer bowing significantly, enabling efficient and repeatable production of multiple wafers from a single substrate.
Implementation Method 1
The process may implant a cleaving ionic species into a crystalline substrate to a first depth from a substrate first surface
Implementation Method 2
the process may implant a non-cleaving ionic species into the crystalline substrate to a second depth from a substrate second surface
Implementation Method 3
followed by thermal energy application to separate the wafer along the separation layer
Data Source
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AI summary
Methods of forming a crystalline wafers such as silicon carbide wafers are disclosed. Such a method may include providing a crystalline substrate comprising a substrate first surface and a substrate second surface opposite the substrate first surface. The method may also include creating a separation layer at a first depth from the substrate first surface and creating a mitigation layer at a second depth from a substrate second surface. Creating the separation layer may cause the crystalline substrate to bow, and creating the mitigation layer may reduce the bow of the crystalline substrate. The method may further include separating the wafer from the crystalline substrate along the separation layer.