SOI Layer Transfer Edge Uniformity via Peripheral Bonding Control
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Solution Overview
Problem
The existing methods for producing silicon-on-insulator (SOI) structures using the SmartCut™ technique often result in an uneven crown width due to excessive bonding strength, leading to a 'jagged edge' phenomenon where small isolated zones of the transferred layer are included in the peripheral crown, causing unevenness in the final product.
Innovation Solution
A method is developed to control the bonding strength between the donor and receiver substrates by ensuring a lower bonding strength in the peripheral area compared to the central area, achieved through controlled plasma activation or cleaning, where the peripheral area is either not exposed to plasma or is locally deactivated, maintaining a width greater than or equal to the initial crown width but less than 10 mm, thereby preventing the jagged edge phenomenon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plasma activation or cleaning is performed to increase bonding strength between substrates, then bonding strength is improved, but the crown width becomes uneven with local enlargement of transferred zones
Solution Approach 1:
The patent applies local quality by differentiating the treatment between central and peripheral areas of the substrate. The peripheral area is either excluded from plasma activation or subjected to a different cleaning protocol compared to the central area, creating spatially varying surface properties that prevent excessive bonding at edges while maintaining strong bonding in the center, thus ensuring uniform crown width
Solution Approach 2:
The substrate surface is segmented into distinct zones (central area and peripheral area) with different treatment protocols. This segmentation allows independent optimization of bonding strength in each zone, preventing the jagged edge phenomenon by ensuring that the peripheral crown area maintains appropriate bonding characteristics separate from the central bonded region
2Reliability
If bonding strength is increased through plasma activation, then bonding reliability is improved, but transferred zones are randomly enlarged towards the edge causing jagged edges
Solution Approach 1:
The invention implements local quality by applying different plasma activation conditions to different regions of the substrate. The peripheral area is either not exposed to plasma or receives reduced plasma treatment compared to the central area, creating a gradient or discontinuity in surface activation that prevents random enlargement of transferred zones at edges while maintaining reliable bonding in the central region
3Area of stationary object
If the peripheral area width is reduced, then the crown becomes narrower, but the risk of transferred zones in the peripheral area increases
Solution Approach 1:
The patent applies local quality by treating the peripheral area differently from the central area through selective plasma activation or cleaning. This creates distinct surface properties in the peripheral zone that prevent transferred zone intrusion regardless of the absolute crown width, ensuring edge evenness is maintained through local surface characteristics rather than solely through geometric dimensions
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 ensures an even edge of the transferred layer without local enlargement, maintaining the width of the crown and reducing the risk of transferred zones in the peripheral area, resulting in a more uniform SOI structure.
Implementation Method 1
Prior to direct wafer bonding, it is possible to bring about plasma activation of the surface of at least one of the substrates. This activation enables the bonding strength to be improved significantly.
Implementation Method 2
a) Implantation of atomic species within the donor substrate, in order to create an embrittlement zone of the same depth as the thickness of the fine layer to be transferred.
Implementation Method 3
b) Bringing into contact of the substrates and direct wafer bonding. The entire surface of the substrates is bonded, except for the periphery
Data Source
AI summary
The invention relates to a method of producing a semiconductor structure by transferring a layer of a donor substrate to a receiver substrate, with the creation of an embrittlement zone in the donor substrate to define the transfer layer, and the treatment of the surface of one of the substrates to increase the bonding strength between them, followed by the direct wafer bonding of the substrates and the detachment of the donor substrate at the embrittlement zone to form the semiconductor structure, in which the surface of the receiver substrate, except for a peripheral crown, is covered with the transferred layer. The treatment of the substrate surface is controlled so that the bonding strength between the substrates is lower in a peripheral area than in a central area. The peripheral area has a width at least equal to the that of the crown and less than 10 mm.