Laser-Formed Wafer Division Layer With Tension-Assisted Slicing
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Solution Overview
Problem
Conventional methods for slicing semiconductor wafers from ingots, such as wire saws and complex laser-based techniques, result in material loss, distortion, and require intricate processes, especially for hard materials like SiC, which are difficult to cut and require extensive man-hours.
Innovation Solution
A dividing device that uses a laser beam to form a division layer within the ingot, with a tension mechanism applying a moment force to slice the wafer using one end of the division layer as a fulcrum, allowing for uniform wafer surface flatness and reduced division force, utilizing a simple structure and known means for moving the laser beam position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If wire saw is used to cut wafer from ingot, then cutting can be performed, but material loss occurs due to cutting margins and distortions and processing damages occur due to contact processing
Solution Approach 1:
The patent replaces the mechanical wire saw cutting system with a laser-based system. The laser beam forms a modified layer inside the ingot without mechanical contact, eliminating both material loss from cutting margins and processing damages from contact. The laser modifies the material structure internally, allowing separation without physical removal of material layers.
Solution Approach 2:
The laser beam预先 forms a modified layer inside the ingot at the desired division position before any separation occurs. This preliminary modification creates a predetermined separation plane that can be cleanly separated later, avoiding the need for material removal and preventing damage to the wafer surfaces.
2Ease of manufacture
If laser beam is used to form modified layer and groove at side wall, then wafer division is achieved, but complicated device and process is required with many man-hours
Solution Approach 1:
The patent extracts the essential function of laser modification while removing the unnecessary groove formation step. By forming the modified layer directly inside the ingot without creating surface grooves, the device complexity is reduced and the process is simplified, eliminating the need for additional v-shaped press-fit materials and associated manufacturing steps.
Solution Approach 2:
The modified layer is formed preliminarily inside the ingot at the exact division position before any separation or additional processing. This preliminary internal modification eliminates the need for subsequent groove formation and press-fit operations, significantly simplifying the overall device and process.
3Ease of manufacture
If heating is applied to upper end of ingot to cause warpage, then wafer division is achieved, but complicated process is required
Solution Approach 1:
The patent replaces the thermal heating method that causes warpage with a localized laser modification approach. Instead of heating the entire upper end of the ingot to induce warpage for separation, the laser precisely modifies the material structure at the division plane, achieving clean separation without complex thermal management or warpage control procedures.
Solution Approach 2:
The laser beam concentrates energy locally at the specific division position within the ingot, creating a modified layer only where needed. This localized modification avoids the need for global heating and warpage induction, simplifying the process while achieving precise wafer division at the desired location.
4Ease of manufacture
If conventional cutting methods are used on high hardness material like SiC, then cutting can be performed, but cutting itself is difficult requiring extensive time and resources
Solution Approach 1:
The patent replaces mechanical cutting methods with laser-based material modification, which is particularly effective for high hardness materials like SiC. The laser modifies the crystal structure or creates a softened layer without requiring mechanical force, dramatically increasing cutting speed and productivity while reducing tool wear and processing difficulty.
Solution Approach 2:
The laser changes the physical and chemical parameters of the SiC material at the division plane, creating a modified layer with different properties that is easier to separate. This parameter change approach allows rapid processing of hard materials without the limitations of mechanical cutting tools, significantly improving productivity.
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
Enables efficient and rapid wafer division with minimal material loss and processing damage, achieving uniform wafer surfaces and simplified manufacturing processes.
Implementation Method 1
a laser beam from a substrate surface (ingot end face) to form a modified layer inside the substrate while condensing the laser beam inside the substrate and relatively moving the condensed position of this laser beam on the substrate
Implementation Method 2
tension means that applies a tensile force to the ingot via the first fixing means and the second fixing means
Implementation Method 3
the tension means rotates one end of the division layer with another end of the division layer as a fulcrums as to generate a moment for slicing the ingot
Implementation Method 4
the wafer is sliced off such that a crack gradually propagates along the division layer by an opening direction (rotation direction) force that is applied to the other end of the division layer
Data Source
Figure 1A~1C
Figure 2
Figure 3A~3C
AI summary
A dividing device for a wafer divides a wafer (Pi) from an ingot (P0) by slicing the ingot by using, as a boundary, a dividing layer (DL) which is formed by relatively moving a laser beam that is condensed to a predetermined depth of the ingot from one of both end faces of the ingot, along the one of both end faces of the ingot. The dividing device for a wafer includes: first fixing means (14a) that fixes the other of the both end faces of the ingot; second fixing means (16a) that is arranged on a first central axis line (XI) of the ingot so as to face the first fixing means and fixes the one of the both end faces of the ingot; and tension means (20A, 20B, 20C) that apply a tensile force to the ingot via the first fixing means and the second fixing means. The tension means rotates one end (b) of the dividing layer with another end (a) of the dividing layer as a fulcrum so as to generate moments (M1, M2) for slicing the ingot with the dividing layer as a boundary.