Alignment Pillar for Semiconductor Package Redistribution Layer
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Solution Overview
Problem
Current semiconductor packages face challenges in accurately forming and aligning redistribution layers, particularly in Package-On-Package structures, which affects the stability and yield of semiconductor chip connections.
Innovation Solution
The semiconductor package design includes a conductive pillar with a connection pillar and an alignment pillar, where the alignment pillar serves as an alignment mark for the photomask, allowing for precise alignment and formation of the redistribution metal pattern, and a method that involves etching the conductive pillar to ensure stable contact with the redistribution metal pattern, thereby facilitating accurate alignment and stable electrical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional semiconductor package structure is used without dedicated alignment features, then the device complexity is reduced, but the manufacturing precision of the redistribution layer deteriorates
Solution Approach 1:
The conductive pillar is segmented into two distinct functional parts: a connection pillar for electrical connection and an alignment pillar for positioning. This segmentation allows each part to be optimized for its specific function, with the alignment pillar providing dedicated alignment features without compromising the electrical connection function of the connection pillar.
Solution Approach 2:
The conductive pillar structure serves multiple functions simultaneously: the connection pillar provides electrical connection while the alignment pillar provides alignment reference. This multi-functionality integrates alignment and connection functions into a single structural element, improving manufacturing precision without adding separate independent components.
2Manufacturing precision
If the conductive pillar is made to extend above the mold layer for better alignment, then the alignment precision improves, but the stability of electrical connection deteriorates
Solution Approach 1:
By separating the conductive pillar into connection pillar and alignment pillar segments, the alignment function is elevated above the mold layer for better visibility and positioning, while the connection pillar remains at the appropriate level for stable electrical connection. This segmentation resolves the conflict between alignment height and connection stability.
Solution Approach 2:
The alignment pillar acts as an intermediary element that provides alignment reference without directly participating in the electrical connection. It mediates between the mold layer and the redistribution layer by providing alignment marks for photomask positioning, while the connection pillar handles the electrical connection function separately.
3Ease of manufacture
If a single-layer conductive pillar is used, then the manufacturing process is simplified, but the alignment accuracy for redistribution layer formation deteriorates
Solution Approach 1:
The conductive pillar is divided into two functional segments (connection pillar and alignment pillar) that can be formed in sequence. The connection pillar is formed first for electrical connection, then the alignment pillar is formed on top for alignment purposes. This segmented approach maintains manufacturing simplicity while significantly improving alignment accuracy through dedicated alignment features.
Data Source
AI summary
A semiconductor package includes a bottom package and an upper redistribution layer disposed on the bottom package. The bottom package includes a substrate and a semiconductor chip disposed on the substrate. A conductive pillar extends upwardly from the substrate and is spaced apart from the semiconductor chip. A mold layer is disposed on the substrate and encloses the semiconductor chip and lateral side surfaces of the conductive pillar. The conductive pillar includes a connection pillar configured to electrically connect the substrate to the upper redistribution layer and an alignment pillar that is spaced apart from the connection pillar. The upper redistribution layer includes a redistribution metal pattern configured to be electrically connected to the connection pillar. A first insulating layer is in direct contact with a top surface of the redistribution metal pattern. A top surface of the alignment pillar is in direct contact with the first insulating layer.