Laser Gettering in Thin Laminated Semiconductor Substrates
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Solution Overview
Problem
It is challenging to form an appropriate gettering region in laminated semiconductor elements as the thickness of the semiconductor substrate is reduced in each layer, making it difficult to achieve both thinning and effective gettering in laminated elements, particularly in semiconductor memory devices like DRAM.
Innovation Solution
A laminated element manufacturing method involving multiple steps of forming and grinding semiconductor wafers with laser-irradiated gettering and modified regions, allowing for precise thinning and accurate cutting while suppressing chipping at the bonding interface, thereby enabling both thinning and appropriate gettering region formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of the semiconductor substrate is reduced to achieve thinning of laminated elements, then the element size is reduced, but it becomes difficult to form an appropriate gettering region
Solution Approach 1:
The patent divides the manufacturing process into multiple sequential stages: forming the gettering region first in the thick substrate, then performing thinning operations, and finally forming cutting grooves. This segmentation allows each step to be optimized independently, ensuring the gettering region is properly formed before thickness reduction occurs.
Solution Approach 2:
The gettering region is formed in advance during the initial manufacturing stage when the substrate is still thick and easier to work with. This preliminary action ensures the gettering structure is established before any thinning or cutting operations that might compromise its integrity.
2Productivity
If blade dicing is used to cut the laminated body, then cutting is performed, but chipping occurs at the bonding interface which significantly reduces yield
Solution Approach 1:
Cutting grooves are formed in advance using laser processing before the actual cutting operation. This preliminary groove formation creates a predetermined fracture path that guides the cutting process and prevents uncontrolled chipping at the bonding interface during blade dicing.
Solution Approach 2:
The patent replaces purely mechanical blade dicing with a hybrid approach that uses laser processing to create cutting grooves first. This substitution of mechanical cutting with laser-assisted groove formation eliminates the chipping problem associated with direct blade contact at bonding interfaces.
3Productivity
If multiple wafers are laminated and processed together, then productivity is improved, but it becomes difficult to maintain appropriate gettering regions in each thin layer
Solution Approach 1:
The patent segments the manufacturing process into wafer-level operations (forming gettering regions in each wafer individually before lamination) and batch-level operations (laminating multiple wafers and performing final cutting together). This allows gettering regions to be properly formed in each layer while maintaining the productivity benefits of processing multiple wafers simultaneously in later stages.
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 allows for the successful thinning of laminated elements while forming an appropriate gettering region, improving yield and reducing flexural strength degradation, and enabling high-efficiency production of laminated elements with precise cutting accuracy.
Implementation Method 1
the semiconductor substrate is irradiated with a laser light in a manufacturing process of a semiconductor device, and a portion of the semiconductor substrate is reformed
Implementation Method 2
a first modified region is formed along a line to cut by irradiating the semiconductor substrate of the first wafer with a laser light along the line to cut
Data Source
AI summary
A laminated element manufacturing method includes a first forming step of forming a first gettering region for each of functional elements by irradiating a semiconductor substrate of a first wafer with a laser light, a first grindsing step of grinding the semiconductor substrate of the first wafer and removing a portion of the first gettering region, a bonding step of bonding a circuit layer of a second wafer to the semiconductor substrate of the first wafer, a second forming step of forming a second gettering region for each of the functional elements by irradiating the semiconductor substrate of the second wafer with a laser light, and a second grinding step of grinding the semiconductor substrate of the second wafer and removing a portion of the second gettering region.