Strip-Shaped UBM Structure for InFO IPD ESR Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The semiconductor industry faces challenges in achieving high performance and reliability in integrated fan-out (InFO) packages due to limitations in under-bump metallization (UBM) structures, particularly in integrating passive devices (IPDs) with high density and reduced equivalent series resistance (ESR) and equivalent series inductance (ESL), while also addressing manufacturing issues like solder bridging and pre-fill voids.
Innovation Solution
The design incorporates strip-shaped and comb-shaped conductive patterns in the UBM structure of IPDs, which are parallel or perpendicular to the top metallization layer, providing high coverage ratios and interleaved power/ground patterns to reduce ESR and ESL, and modified conductive patterns in the InFO package to prevent solder bridging and pre-fill voids.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional UBM structures are used in InFO packages, then manufacturing is simpler, but ESR and ESL are higher and reliability is reduced
Solution Approach 1:
The UBM structure is segmented into multiple conductive patterns (strip-shaped and comb-shaped) with different orientations. These segmented patterns are interleaved to create multiple parallel current paths, which reduces ESR and ESL while maintaining manufacturing feasibility through standardized fabrication processes.
Solution Approach 2:
The invention transitions from conventional planar UBM patterns to three-dimensional interleaved structures with conductive patterns extending in multiple dimensions. The strip-shaped and comb-shaped patterns are positioned at different heights and orientations, creating a multi-dimensional conductive network that reduces electrical resistance and inductance.
2Reliability
If conductive patterns are added to reduce ESR and ESL, then IPD performance improves, but manufacturing complexity increases
Solution Approach 1:
The strip-shaped and comb-shaped conductive patterns are merged into a single integrated UBM structure that is formed in one fabrication process. This combined structure achieves ESR and ESL reduction while avoiding the need for separate manufacturing steps, thereby maintaining ease of manufacture.
Solution Approach 2:
The invention changes the geometric parameters of the conductive patterns (shape, orientation, spacing) to optimize electrical performance. By carefully controlling these parameters during a single fabrication process, the structure achieves low ESR and ESL without increasing manufacturing complexity.
3Productivity
If modified conductive patterns are used to prevent solder bridging, then manufacturing yield improves, but ESR may increase
Solution Approach 1:
The UBM structure employs local quality variations where conductive patterns are strategically positioned and dimensioned to provide different functions in different regions. Areas with tighter spacing prevent solder bridging, while interleaved patterns in other regions maintain low ESR and ESL, achieving both manufacturing yield and electrical performance.
Data Source
AI summary
A semiconductor package includes an integrated passive device (IPD) including one or more passive devices over a first substrate; and metallization layers over and electrically coupled to the one or more passive devices, where a topmost metallization layer of the metallization layers includes a first plurality of conductive patterns; and a second plurality of conductive patterns interleaved with the first plurality of conductive patterns. The IPD also includes a first under bump metallization (UBM) structure over the topmost metallization layer, where the first UBM structure includes a first plurality of conductive strips, each of the first plurality of conductive strips electrically coupled to a respective one of the first plurality of conductive patterns; and a second plurality of conductive strips interleaved with the first plurality of conductive strips, each of the second plurality of conductive strips electrically coupled to a respective one of the second plurality of conductive patterns.