Silicon Interposer Trench Alignment via Mask Merging
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Solution Overview
Problem
The existing manufacturing methods for silicon interposers require at least three masks and multiple metal filling/planarization processes, resulting in a complex and costly process for forming Through-Silicon Via (TSV) structures and re-distribution layers.
Innovation Solution
A manufacturing method that uses fewer masks by forming shallow trenches with a first mask and using them as alignment marks for forming deep trenches with a second mask, followed by metal filling and planarization to create metal damascene structures in both shallow and deep trenches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If three masks and multiple metal filling/planarization processes are used to form TSV structures and RDL, then the manufacturing precision and reliability are improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent combines the formation of alignment marks and TSV trenches into a single lithography step using one mask. The mask simultaneously defines both the shallow trenches (alignment marks) and deep trenches (TSV structures), eliminating the need for separate mask steps and reducing process complexity while maintaining manufacturing precision
Solution Approach 2:
The patent performs preliminary formation of shallow trenches with metal filling to create alignment marks before forming the deep TSV trenches. This preliminary action establishes reference features that guide subsequent etching processes, ensuring precise TSV formation without requiring additional alignment masks
2Manufacturing precision
If three masks are used for forming TSV structures and RDL, then the manufacturing precision is improved, but the loss of time and productivity decrease
Solution Approach 1:
Multiple trench formations (alignment marks and TSV structures) are merged into a single lithography and etching cycle. One mask pattern simultaneously defines both shallow and deep trenches, eliminating sequential mask steps and significantly improving manufacturing throughput while preserving alignment precision
Solution Approach 2:
Alignment mark trenches are formed preliminarily in the same lithography step as TSV trenches. The shallow trenches serve as pre-formed references that enable precise alignment for subsequent metal filling and planarization processes without requiring additional mask alignment steps
3Manufacturing precision
If multiple metal filling and planarization processes are performed, then the manufacturing precision of TSV and RDL is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the formation of TSV structures and RDL trenches into a unified process flow. Both shallow and deep trenches are formed in the same lithography and etching steps, and metal filling is performed simultaneously for both trench types, reducing the number of discrete manufacturing steps and associated costs while maintaining precision
Data Source
AI summary
An interposer structure including a semiconductor substrate, a plurality of shallow trenches, a plurality of deep trenches and a plurality of metal damascene structures is provided. The semiconductor substrate has a first surface and a second surface opposite to each other. The shallow trenches are formed on the first surface in both of a first area and a second area of the semiconductor substrate and correspondingly a plurality of respective openings are formed on the first surface. The deep trenches extend from at least one of the shallow trenches toward the second surface in the second area and correspondingly a plurality of respective openings are formed on the second surface. The metal damascene structures are filled in both of the shallow trenches and the deep trenches. A manufacturing method for the aforementioned interposer structure is also provided.