Wafer Expanding Tape Sticking for Crack-Free Chip Separation
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Solution Overview
Problem
Existing methods for dividing wafers to form device chips often result in chipping or distortion, leading to reduced flexural strength, and the use of expanding tape can cause unintended cracking or failure in dividing and product defects.
Innovation Solution
A manufacturing method involving modified layer formation, grinding, and controlled application of expanding tape using a tape sticking apparatus with a pressing roller that operates multiple times to apply consistent pressure, ensuring proper tape adhesion and preventing excessive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the expanding tape is strongly pressed to ensure proper adhesion, then the tape sticking reliability is improved, but cracks may extend from modified layers causing product defects
Solution Approach 1:
The pressing roller performs multiple pressing operations (at least two times) before the expanding tape is fully expanded. This preliminary repeated pressing ensures thorough adhesion between the tape and wafer back surface before expansion forces are applied, preventing tape detachment while avoiding excessive single-instance pressure that could cause cracking
Solution Approach 2:
The pressing operation is executed periodically multiple times rather than as a single continuous action. This periodic pressing allows the adhesive to set progressively and ensures uniform adhesion across the tape surface, achieving reliable bonding without applying excessive force at any single moment
2Productivity
If the wafer is divided by cutting blade or laser ablation, then the dividing process is completed, but chipping or distortion occurs reducing flexural strength
Solution Approach 1:
Modified layers are formed inside the wafer along the planned dividing lines before the actual dividing process. These pre-formed modified layers serve as predetermined fracture paths that guide the division process, ensuring clean separation without chipping or distortion of the chip edges
Solution Approach 2:
The conventional mechanical cutting blade method is replaced with a laser-based modified layer formation process. The laser creates controlled modification zones within the wafer that act as stress concentration points, guiding fracture along precise paths without mechanical contact that could cause chipping
3Ease of manufacture
If the expanding tape is not properly stuck to the wafer, then the wafer can be divided, but the tape fails to provide sufficient tensile force for proper dividing
Solution Approach 1:
The expanding tape is thoroughly pressed onto the wafer back surface using the pressing roller multiple times before expansion. This preliminary adhesion ensures that when the tape is subsequently expanded, the tensile force is effectively transmitted to the wafer through the bonded interface, enabling proper dividing action
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 suppresses failures in dividing and product defects, achieving a 100% dividing rate with no defects, compared to 60-80% in previous methods, by ensuring proper tape adhesion and controlled pressure application.
Implementation Method 1
positioning the focal point of a laser beam with a wavelength having transmissibility with respect to the wafer to the inside of the wafer and executing irradiation to form modified layers that become points of origin of dividing
Implementation Method 2
grinding a back surface of the wafer by grinding means to thin the wafer into a finished thickness and dividing the wafer into the chips along the planned dividing lines
Implementation Method 3
sticking an expanding tape having elasticity to the back surface of the wafer for which grinding processing has been executed and an expanding step of expanding the expanding tape and widening an interval between the chips along the planned dividing lines
Data Source
AI summary
A manufacturing method of chips includes forming modified layers that become points of origin of dividing along planned dividing lines, grinding the back surface of the wafer by grinding abrasive stones to thin the wafer into a finished thickness, and dividing the wafer into the chips along the planned dividing lines using the modified layers as the points of origin. The manufacturing method also includes sticking an expanding tape having elasticity to the back surface of the wafer for which grinding processing has been executed, expanding the expanding tape and widening the interval between the respective chips along the planned dividing lines.