Liquid Ejection Head Wafer Dicing via Backside Recessed Portions
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Solution Overview
Problem
Conventional methods for manufacturing liquid ejection heads face challenges with dimensional accuracy and chipping during the dicing process, leading to instability in the outer shape of element substrates and reduced production yield due to poor control over bending and tensile forces, as well as complications in forming recessed portions at the intersection of cutting lines.
Innovation Solution
A method involving the formation of recessed portions on the back surface of the wafer, where the recessed portion overlaps cutting lines except at the intersection, allowing for precise cutting and reducing the likelihood of chipping and cracking by ensuring accurate alignment and stress distribution during dicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If wet etching is used to form recessed portions at cutting lines, then chipping is reduced, but dimensional accuracy deteriorates at intersection portions
Solution Approach 1:
The recessed portion formation process is segmented into two distinct operations: first forming recessed portions at non-intersection cutting lines, then forming recessed portions at intersection cutting lines. This segmentation allows each operation to be optimized independently, preventing the dimensional accuracy deterioration that occurs when attempting to form all recessed portions in a single wet etching process.
Solution Approach 2:
Recessed portions at non-intersection cutting lines are formed in advance before the wafer is subjected to bending or tensile forces. This preliminary action ensures that these recessed portions are established with high dimensional accuracy before any forces that could cause deformation are applied, thereby preventing both chipping and dimensional inaccuracy.
2Ease of manufacture
If bending force or tensile force is applied to cut the wafer, then cutting is achieved, but dimensional accuracy and control become extremely poor
Solution Approach 1:
Recessed portions are formed in advance on the wafer surface before any bending or tensile forces are applied. This preliminary formation of recessed portions creates stress concentration points that guide the cracking process, allowing the wafer to be separated with much better dimensional accuracy and control than would be possible through force application alone.
Solution Approach 2:
The recessed portions act as intermediary structures that mediate between the applied bending/tensile forces and the final cut line. These recessed portions concentrate and direct the mechanical forces along the desired cutting path, transforming uncontrolled force application into precise cutting while maintaining dimensional accuracy.
3Object-affected harmful factors
If recessed portion is formed at intersection of cutting lines, then chipping is prevented, but shape control becomes extremely difficult
Solution Approach 1:
The formation of recessed portions at intersection cutting lines is segmented into a separate, subsequent process step after non-intersection recessed portions are formed. This allows the intersection recessed portions to be formed with optimized parameters specifically tailored for intersection geometry, achieving both chipping prevention and shape control that would be impossible in a unified process.
Solution Approach 2:
Different formation conditions and parameters are applied to recessed portions based on their location: non-intersection recessed portions use one set of formation parameters, while intersection recessed portions use different parameters optimized for their complex geometry. This local quality approach ensures each type of recessed portion achieves optimal chipping prevention and shape control appropriate to its specific location and function.
Data Source
AI summary
A method for manufacturing a liquid ejection head including an element substrate having an ejection port forming member including an ejection port and an energy generating element for supplying energy for ejecting liquid to the ejection port includes preparing a wafer having the energy generating element and the ejection port forming member on a first surface, forming a recessed portion in a second surface, and cutting the wafer. The wafer is cut along cutting lines provided on the first surface to form element substrates and including a first cutting line and a second cutting line intersecting the first cutting line. The recessed portion is formed at a position overlapping the cutting lines except in an intersection portion of the first and second cutting lines. In the intersection portion, the recessed portion is formed corresponding to only one of the first cutting line and the second cutting line.