Workpiece Division via Laser-Induced Brittleness and Expanding Sheet
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Solution Overview
Problem
Existing methods for dividing plate-shaped workpieces, such as wafers, face challenges in ensuring complete division without adjacent chips coming into contact and damaging each other, particularly when dealing with high hardness or thick workpieces with multiple planned dividing lines.
Innovation Solution
A method involving forming a starting point region along planned dividing lines using multiphoton absorption with a laser beam, followed by heating to extend cracks and make the region more brittle, and then applying a force using an expanding sheet to divide the workpiece, eliminating the need for a thin plate-shaped member to prevent chip contact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a thin plate-shaped member is used to pressurize the workpiece for division, then the workpiece can be divided along the planned dividing line, but adjacent chips may move and come into contact with each other causing damage
Solution Approach 1:
The patent replaces the mechanical pressurization method (thin plate-shaped member) with a thermal field method (laser heating). The laser heating creates thermal stress and modifies the material properties along the dividing line, enabling division without mechanical contact that could cause chip damage.
Solution Approach 2:
The patent changes the physical state and properties of the workpiece material through controlled heating. By raising the temperature locally along the dividing line, the material undergoes thermal expansion and property changes that facilitate clean separation without the need for mechanical force that could damage adjacent chips.
2Object-affected harmful factors
If an expanding sheet is used to apply force for division, then chips are prevented from contacting each other, but the force may be insufficient for high hardness or thick workpieces
Solution Approach 1:
The patent replaces the mechanical expanding sheet method with laser heating. The thermal energy from the laser creates internal thermal stress and modifies material properties, generating sufficient force for division in high hardness or thick workpieces without requiring external mechanical expansion that might be insufficient.
Solution Approach 2:
The laser heating is applied in a controlled, periodic manner along the dividing line, creating sequential thermal modification that propagates through the workpiece material, enabling progressive division without requiring excessive force all at once.
3Reliability
If the workpiece is heated to extend cracks and increase brittleness, then division becomes more reliable, but additional heating and cooling steps are required
Solution Approach 1:
The patent combines the crack extension function and the division function into a single laser heating step. The heating simultaneously extends existing cracks and creates new fracture paths, eliminating the need for separate mechanical expansion steps and reducing overall process complexity despite adding thermal 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 ensures more reliable and complete division of workpieces without adjacent chips contacting each other, effectively addressing the limitations of existing techniques by enhancing the brittleness of the starting point region and using a force that expands the sheet to separate the workpiece along planned lines.
Implementation Method 1
forming a starting point region serving as a starting point of division along a planned dividing line set on the workpiece; the starting point region forming step may form a plurality of fine holes reaching one surface from an inside of the workpiece along the planned dividing line by irradiating the workpiece with a laser beam
Implementation Method 2
heating the workpiece after performing the starting point region forming step; cracks are further extended from the starting point region of the workpiece, and the starting point region of the workpiece and the periphery thereof are made further brittle
Implementation Method 3
cooling the workpiece after performing the heating step
Implementation Method 4
dividing the workpiece along the starting point region by applying a force to the workpiece after performing the cooling step; the dividing step applying the force to the workpiece by expanding the expanding sheet
Data Source
AI summary
There is provided a dividing method for dividing a plate-shaped workpiece. The dividing method includes: a starting point region forming step of forming a starting point region serving as a starting point of division along a planned dividing line set on the workpiece; a heating step of heating the workpiece after performing the starting point region forming step; a cooling step of cooling the workpiece after performing the heating step; a dividing step of dividing the workpiece along the starting point region by applying a force to the workpiece after performing the cooling step; and a sheet affixing step of affixing an expanding sheet to the workpiece before performing the dividing step; the dividing step applying the force to the workpiece by expanding the expanding sheet.