Semiconductor Bump Formation Control via Insulating Film
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Solution Overview
Problem
The formation of small bumps at the intersections of the light-shielding ring and regular-size bumps in semiconductor devices can cause adhesion issues during probe inspection, leading to malfunctions as these small bumps may stick to probe needles and come off from semiconductor chips.
Innovation Solution
The implementation of a bump-formation insulating film with specific openings over pad electrodes, along with the formation of dummy bumps in non-effective areas, prevents bump formation near the sealing member, ensuring that bumps are formed within a controlled distance from the sealing member and preventing adhesion to probe needles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a light-shielding ring is placed over the resist film to prevent bump formation near the sealing member, then bumps are prevented from forming within the restricted distance from the sealing member, but small bumps are formed at intersections of the light-shielding ring edge and bump formation areas
Solution Approach 1:
The patent applies local quality by making the bump formation insulating film transparent in specific local areas (where bumps should form) and opaque in other local areas (where bumps should not form). This spatial variation in optical properties allows precise control of bump formation locations, preventing small bumps at light-shielding ring intersections while enabling regular bump formation in effective areas.
Solution Approach 2:
The bump formation insulating film acts as an intermediary layer between the resist film and the electrode. It mediates the light exposure process by selectively transmitting or blocking light in different regions, thereby controlling where bumps form during electroplating without requiring direct light-shielding structures that cause intersection problems.
2Reliability
If the peripheral edge portion of the wafer is blocked from light during exposure, then bump formation is prevented near the sealing member, but small bumps still form at the edge intersections
Solution Approach 1:
The bump formation insulating film has spatially varying optical properties - transparent regions allow light transmission for bump formation in effective areas, while opaque regions block light to prevent bump formation in non-effective areas near the periphery. This eliminates the small bump formation problem at light-shielding ring intersections.
3Productivity
If regular electroplating is performed without special measures, then bumps form over the entire wafer surface, but bumps form too close to the sealing member causing adhesion issues
Solution Approach 1:
The bump formation insulating film creates local quality differences in light transmission, allowing efficient bump formation in effective areas while preventing bump formation in non-effective peripheral areas. This maintains productivity in useful regions while achieving precise bump positioning control by eliminating unwanted bumps near the sealing member.
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 approach effectively prevents bumps from sticking to probe needles during inspection, reducing the likelihood of malfunctions and ensuring reliable semiconductor chip inspection by controlling bump formation and size through the use of dummy bumps and strategic placement of the bump-formation insulating film.
Implementation Method 1
a photosensitive film is exposed to light and then is developed
Implementation Method 2
an electrode is coupled to the seed metal film positioned at an edge of the wafer to supply electric power and the wafer is immersed in a plating solution. Through these steps bumps grow in the openings of the resist pattern
Data Source
AI summary
The present invention prevents bumps on semiconductor chips from sticking to probe needles and coming off from the semiconductor chips. A wafer has effective areas where a plurality of bumps (first bumps) are formed. The bumps are formed on the side of an active surface of the semiconductor chips. The wafer further has non-effective areas where a plurality of dummy bumps are formed. Among the dummy bumps, some positioned at the outermost circumference are dummy bumps (second bumps) that are smaller than the other bumps. The dummy bumps (second bumps) intersect the inner peripheral edge of a shielding member as viewed in a plan view. The dummy bumps (second bumps) are formed over third pad electrodes. A bump-formation insulating film is removed from over the entire third pad electrodes.