Composite Substrate Void Prevention via Laser Curvature Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The manufacturing of semiconductor elements using composite substrates often results in voids at the joined interface due to surface shape irregularities, leading to reduced quality and increased costs, especially when only one surface is mirror polished or both surfaces are uniformly polished but include minute undulations.
Innovation Solution
A composite substrate manufacturing method that involves deforming at least one substrate to have a mirror surface warp outward, allowing for a protruding surface to join with another substrate, either flat or warped, to prevent voids at the interface, using techniques like laser irradiation to form heat denatured layers and adjust curvature within specific ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If only one surface of the first substrate is mirror polished, then the cost is reduced, but voids appear on the joined interface due to warpage
Solution Approach 1:
The patent applies preliminary action by forming a convex shape on the rough-polished surface before joining. This pre-shaping compensates for the warpage that would otherwise cause voids, allowing the use of only one mirror-polished surface while maintaining joined interface quality.
Solution Approach 2:
The patent introduces asymmetry by creating a convex shape on only the rough-polished surface, rather than making both surfaces symmetric. This asymmetric modification allows the rough surface to compensate for warpage without requiring mirror polishing of the second surface.
2Manufacturing precision
If both surfaces of the first substrate are mirror polished, then the joined interface quality is improved, but the cost significantly increases
Solution Approach 1:
The patent applies partial action by mirror polishing only one surface (the excessive side) and compensating with the convex shape on the rough surface. This partial approach achieves sufficient joined interface quality without the excessive cost of polishing both surfaces.
Solution Approach 2:
The patent uses asymmetry by making only one surface mirror-polished while creating a convex shape on the rough surface. This asymmetric combination achieves the needed interface quality at lower cost than symmetric double-polishing.
3Manufacturing precision
If both surfaces are uniformly mirror polished, then the surface flatness is improved, but minute undulations remain causing voids
Solution Approach 1:
The patent applies local quality by creating a convex shape specifically on the rough-polished surface where it is needed for warpage compensation. This localized modification addresses the void problem without requiring perfect flatness across the entire surface.
Solution Approach 2:
The patent uses preliminary anti-action by pre-forming the convex shape to counteract the warpage-induced voids. This pre-compensation prevents the harmful effect of voids before joining occurs, even when minute undulations are present on mirror-polished surfaces.
4Reliability
If the substrate is deformed to warp outward, then voids are prevented at the joined interface, but additional processing steps are required
Solution Approach 1:
The patent replaces complex mechanical warpage control systems with a simpler convex shaping process. Instead of using complex mechanical means to control substrate warpage, the invention uses direct convex shape formation on the rough surface, reducing processing complexity.
Solution Approach 2:
The patent changes the surface geometry parameter by forming a convex shape with a specific radius of curvature (5mm to 50mm). This parameter modification achieves warpage compensation and void prevention through a controlled geometric change rather than complex processing.
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 inhibits the appearance of voids at the joined interface, enhancing the quality and yield of semiconductor elements while reducing costs by ensuring proper contact and expulsion of air or fluid between the substrates during the joining process.
Implementation Method 1
irradiation of a laser to the first raw board focusing on, of two regions formed by dividing the first raw board into two in a thickness direction, an inside of a region of the first raw board on a side to be joined to the second substrate after the first raw board becomes the first substrate through the first raw board deforming step, thereby forming a heat denatured layer in the region
Data Source
AI summary
Provided is a composite substrate manufacturing method, including at least: a first raw board deforming step of preparing a first substrate by deforming a first raw board having at least one surface as a minor surface into a state in which the minor surface warps outward; and a joining step of joining, after the first raw board deforming step, a protruding surface of the first substrate and one surface of a second substrate to each other, thereby manufacturing a composite substrate including the first substrate and the second substrate, in which the second substrate is any one substrate selected from a substrate having both surfaces as substantially flat surfaces and a substrate that warps so that a surface thereof to be joined to the first substrate warps outward. Also provided are a semiconductor element manufacturing method, a composite substrate and a semiconductor element manufactured.