Electrode Pad Rewiring Layer for Wafer Level Package Corrosion
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Solution Overview
Problem
In semiconductor device fabrication, especially for wafer level chip size packages, the formation of probe marks on electrode pads during testing can lead to adhesion issues and corrosion when moisture enters, particularly when the probe marks are tall and the rewiring layer coverage is incomplete, affecting the reliability of the device.
Innovation Solution
A method and structure where the insulating film and rewiring layer are formed to cover the test region of the electrode pad, with the rewiring layer extending to cover the upper part of the probe mark projection, preventing direct contact with the encapsulation resin and ensuring reliable coverage even with tall probe marks, using a sequence of barrier and plating seed layers for electrolytic plating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the electrode pad for test is covered with the rewiring layer, then the adhesion between insulating film and electrode pad is improved, but the manufacturing complexity increases due to additional plating seed layer formation
Solution Approach 1:
The patent applies preliminary action by forming the plating seed layer in advance before the rewiring layer. This seed layer is deposited on the electrode pad surface (including probe mark regions) prior to the main rewiring layer formation, ensuring that even areas with tall probe marks will have proper adhesion and plating foundation. This preliminary preparation resolves the adhesion issue without requiring complex post-processing.
Solution Approach 2:
The patent segments the electrode pad into two functional regions: a test region that receives probe marks and a connection region for rewiring. By spatially separating these functions and applying different treatment strategies to each region, the patent manages the complexity-adhesion tradeoff effectively. The test region gets the plating seed layer for adhesion, while the connection region receives the full rewiring structure.
2Reliability
If the rewiring layer is formed to cover the probe mark, then the corrosion resistance is improved, but the manufacturing precision requirement increases due to incomplete coverage of tall probe marks
Solution Approach 1:
The plating seed layer is formed as a preliminary action before the main rewiring layer. This seed layer completely covers the electrode pad surface including tall probe marks, creating a uniform base that eliminates coverage gaps. The subsequent rewiring layer then deposits uniformly on this prepared surface, ensuring complete corrosion protection without requiring extremely precise alignment.
Solution Approach 2:
The plating seed layer acts as an intermediary between the electrode pad (with probe marks) and the main rewiring layer. This intermediate layer fills in the gaps caused by tall probe marks and provides a continuous, uniform surface for the rewiring layer, mediating the transition from an uneven substrate to a smooth, fully covered conductive layer.
3Reliability
If a thick insulating film is formed to cover the probe mark, then the corrosion protection is improved, but the ease of manufacture deteriorates due to difficulty in forming contact holes
Solution Approach 1:
The patent extracts the corrosion protection function from the insulating film and assigns it to the rewiring layer instead. By removing the insulating film from the electrode pad surface (forming an opening) and allowing the conductive rewiring layer to provide the protective coverage, the patent eliminates the need for thick insulating films while maintaining corrosion protection. Contact holes can then be formed easily through the thinner insulating film.
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 prevents corrosion and ensures high reliability by covering the probe mark tip with the rewiring layer, maintaining device integrity under humidity tests and ensuring consistent operational characteristics.
Implementation Method 1
The plating seed layer can be formed by sputtering.
Implementation Method 2
the rewiring layer is made of Cu or the like and formed by electrolytic plating
Data Source
AI summary
There is provided a semiconductor device including a semiconductor substrate on which at least one electrode pad is formed, a rewiring layer connected to the electrode pad, and an encapsulation part which encapsulates the semiconductor substrate, the electrode pad being formed of a first region including a connection part connected to the rewiring layer and a second region other than the first region, the device including: an insulating film provided on the semiconductor substrate, having an opening at which the first region in the electrode pad is exposed, and covering the second region of the electrode pad, wherein the rewiring layer is connected to the first region of the electrode pad exposed at the opening, and extends across the insulating film so as to cover the second region of the electrode pad from above.