Embedded Trace Substrate Protruding Bump Pads
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Solution Overview
Problem
Existing embedded trace substrate manufacturing processes result in recessed bump pads due to over-etching, leading to reliability issues such as inadequate bonding strength between semiconductor chips and bond pads, which can cause mechanical and electrical property deterioration.
Innovation Solution
The formation of bump pads that protrude outward from the dielectric film by a predetermined height, increasing the bonding area and enhancing interfacial bonding strength, achieved through processes like photo-mask etching and selective removal of conductive layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a blanket front etching process is used to globally remove portions of the metal bump pattern, then the etching process can be simplified and carried out uniformly, but the bump pads become recessed below the top surface of the dielectric film due to over-etching, leading to bonding problems and reliability issues
Solution Approach 1:
The patent applies local quality by introducing a sacrificial film only in specific regions where bump pads are to be formed, rather than uniformly treating the entire substrate. This localized approach allows selective protection of metal bump pattern portions, enabling precise control over bump pad depth while maintaining the simplicity of blanket etching elsewhere.
Solution Approach 2:
The sacrificial film is formed in advance before the blanket etching process, serving as a pre-prepared protective layer. This preliminary action ensures that the metal bump pattern portions requiring protection are already covered before etching begins, preventing over-etching and recessed bump pads while allowing the etching process to proceed uniformly.
2Productivity
If the bump pads are recessed approximately 5-7 micrometers or more below the top surface of the dielectric film, then the blanket front etching process can be completed, but the bonding area becomes too thin and small, causing bonding problems between semiconductor chip and bond pads
Solution Approach 1:
The sacrificial film provides localized protection only where bump pads are formed, creating a quality difference between protected and unprotected regions. This ensures that bump pads maintain adequate height and bonding area in critical regions while allowing the etching process to complete uniformly across the entire substrate.
Solution Approach 2:
The sacrificial film acts as an intermediary protective layer between the etching process and the metal bump pattern. It mediates the etching action by being selectively removed after etching, thereby protecting the bump pads from excessive etching while allowing the etching process to proceed to completion.
3Ease of manufacture
If over-etching occurs during the blanket front etching process, then the etching can be carried out uniformly across the substrate, but the mechanical and electrical properties of the packaged device deteriorate due to inadequate bonding area
Solution Approach 1:
The sacrificial film creates local quality differentiation by protecting specific regions (bump pad areas) from etching while allowing other regions to be etched uniformly. This localized protection prevents the harmful effect of over-etching in critical areas while maintaining the simplicity and uniformity of the blanket etching process overall.
Solution Approach 2:
The sacrificial film converts the potentially harmful blanket etching process into a beneficial selective etching process. By introducing this protective layer, the uniform etching action is transformed into a controlled process that protects critical structures, turning a harmful over-etching effect into a beneficial selective protection mechanism.
Data Source
AI summary
In one embodiment, a method for forming an embedded trace substrate includes forming a conductive layer on a carrier. A dielectric film is provided on the conductive layer. Vias are formed in the dielectric film and extend to portions of the conductive layer. A conductive pattern is formed on the dielectric layer and is electrically connected to the conductive layer through the vias. The carrier is removed and portions of the conductive layer are selectively removed to provide a plurality of bumps pads configured to protrude outwardly from the dielectric layer.