CSP Semiconductor Pad Electrode Corrosion Protection
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Solution Overview
Problem
Conventional BGA type semiconductor devices have reliability issues due to corrosion caused by substances like moisture, chemicals, and metal ions infiltrating through exposed portions between the passivation film and plating layer, leading to reduced device reliability.
Innovation Solution
A semiconductor device with a two-step passivation film structure and a larger plating layer coverage, where the second passivation film covers the edge portion of the plating layer and the first passivation film, preventing corrosion by filling gaps and covering exposed portions of the pad electrode, and a conductive terminal is formed on the plating layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single passivation film structure is used, then the manufacturing process is simple, but corrosion resistance is poor due to exposed portions between the passivation film and plating layer
Solution Approach 1:
The passivation film is divided into two separate layers: a first passivation film formed over the pad electrode, and a second passivation film formed over the plating layer. This segmentation ensures that each layer can be optimized for its specific function, with the first layer providing initial protection and the second layer providing additional corrosion resistance, thereby eliminating exposed portions and improving overall reliability without requiring a single complex multi-functional layer
Solution Approach 2:
The first passivation film is formed in advance before the plating layer is deposited. This preliminary action ensures that the pad electrode is already protected before plating begins, and the subsequent formation of the second passivation film completes the protection system. This sequence of actions prevents corrosion from the outset rather than attempting to address exposed portions after the fact
2Reliability
If the plating layer coverage is increased to cover exposed portions, then corrosion resistance improves, but manufacturing precision requirements increase
Solution Approach 1:
Instead of requiring the plating layer to extend beyond the pad electrode boundaries with high precision, the protection function is segmented between the first passivation film (which covers the pad electrode) and the second passivation film (which covers the plating layer). This segmentation relaxes the precision requirements for plating layer alignment while still achieving complete corrosion protection
Solution Approach 2:
The first passivation film acts as an intermediary layer between the pad electrode and the plating layer, providing a buffer zone that eliminates the need for precise plating layer extension. This intermediary structure allows for more tolerant manufacturing tolerances while maintaining complete coverage and corrosion resistance
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
Enhances the reliability of the semiconductor device by preventing corrosion and improving resistance to environmental factors, ensuring the longevity and performance of the semiconductor device.
Implementation Method 1
a plating layer 106 having a layered structure of nickel (Ni) and gold (Au) is formed on the pad electrode 103 exposed in the opening 105 by an electrolytic plating method or an electroless plating method
Implementation Method 2
a plating layer 106 having a layered structure of nickel (Ni) and gold (Au) is formed on the pad electrode 103 exposed in the opening 105 by an electrolytic plating method or an electroless plating method
Implementation Method 3
a solder ball is fixed to a predetermined region of the plating layer 106 by an electrolytic plating method or an electroless plating method, thereby forming a conductive terminal 108
Data Source
AI summary
The invention provides a CSP type semiconductor device with high reliability. The semiconductor device includes a pad electrode formed on a semiconductor substrate, a first passivation film covering an end portion of the pad electrode and having a first opening on the pad electrode, a plating layer formed on the pad electrode in the first opening, a second passivation film covering an exposed portion of the pad electrode between an end portion of the first passivation film and the plating layer, covering an end portion of the plating layer, and having a second opening on the plating layer, and a conductive terminal formed on the plating layer in the second opening.