RDL Contact Alignment to TSVs Without Extra Passivation Layers

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Solution Overview

Problem

The semiconductor industry faces challenges in packaging semiconductor dies due to the need for smaller feature sizes and increased integration density, particularly in Package-on-Package (PoP) technology, where the formation of through silicon vias (TSVs) and through mold vias (TMVs) requires additional passivation layers to accommodate different critical dimensions, increasing manufacturing complexity and costs.

Innovation Solution

The proposed solution involves forming a passivation layer that can accommodate the smaller critical dimensions of TSVs without the need for additional layers, by using a process that recesses the top surface of the die and forms a patterned passivation layer to expose TSVs and TMVs, allowing for the formation of a re-distribution layer (RDL) with contact features that can be electrically and physically connected to the vias, thereby simplifying the manufacturing process and reducing costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If additional passivation layers are added to accommodate different critical dimensions of TSVs and TMVs, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:

Improvecritical dimension accommodationVSAvoidpassivation layer structure

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies local quality by creating different regions within the same passivation layer structure. The first passivation layer is selectively removed at via locations to expose TSVs, while the second passivation layer is selectively removed at pad locations to expose TMVs. This localized differentiation allows a single passivation layer structure to accommodate different critical dimensions for different via types, eliminating the need for additional separate passivation layers while maintaining manufacturing precision.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of adding more passivation layers to handle different critical dimensions (the conventional approach), the patent inverts the strategy by using a single passivation layer structure that is selectively removed in different patterns. The first passivation layer is removed to expose TSVs, and the second passivation layer is removed to expose TMVs, thereby solving the critical dimension accommodation problem through subtraction rather than addition.

Inventive Principle:

Principle #13The other way round (Inversion)

2Manufacturing precision

If additional passivation layers are added to accommodate different critical dimensions, then manufacturing precision is improved, but ease of manufacture deteriorates

Engineering Contradiction:

Improvecritical dimension accommodationVSAvoidmanufacturing process simplicity

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent merges the functions of multiple passivation layers into a single integrated passivation layer structure. Both the first and second passivation layers are formed as part of the same overall passivation structure, with selective removal patterns that accommodate different critical dimensions for TSVs and TMVs. This consolidation simplifies the manufacturing process by reducing the number of separate passivation layer formation steps while maintaining the precision needed for different via types.

Inventive Principle:

Principle #5Merging (Combining)

3Productivity

If feature sizes are reduced to increase integration density, then productivity is improved, but manufacturing precision requirements increase

Engineering Contradiction:

Improveintegration densityVSAvoidfeature size control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent employs parameter changes by varying the critical dimensions of the first and second passivation layers to match the different via sizes. The first passivation layer has a first critical dimension configured to match the first via size, while the second passivation layer has a second critical dimension configured to match the second via size. This parameter differentiation within a unified structure allows reduced feature sizes for higher integration density while maintaining appropriate precision control for each via type.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20230402429A1Methods of Forming Packages and Resulting Structures

Publication Date: 2023.12.14 TAIWAN SEMICONDUCTOR MANUFACTURING CO LTD

AI summary

Manufacturing flexibility and efficiency are obtained with a method, and resulting structure, in which RDL contact features can be formed and aligned to through silicon vias (TSV's) regardless of any potential mismatch in the respective critical dimensions (CD's) between the manufacturing process for forming the TSV's and the manufacturing process for forming the contact features. Various processes for a self-aligned exposure of the underlying TSV's, without the need for additional photolithography steps are provided.