External Getter Layout for Wafer-Level Vacuum Pressure Control
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Solution Overview
Problem
As die sizes shrink, the available space for getters in wafer level packages (WLPs) decreases, increasing the risk of contamination and reducing their effectiveness in maintaining vacuum pressure.
Innovation Solution
Depositing a layer of getter material on the external regions of the wafers, such as the saw-to-reveal (STR) regions, to compensate for the reduced internal space and enhance getter capacity, thereby reducing contamination and maintaining vacuum pressure during the bonding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If die sizes are shrunk to reduce package size, then productivity and device density are improved, but the available space for getters is reduced and contamination risk increases
Solution Approach 1:
The invention extends the getter material deposition from the traditional internal WLP region only to include the external STR region. This dimensional expansion of the getter coverage area compensates for the reduced internal space, providing sufficient getter capacity even as die sizes shrink and internal getter space is reduced.
Solution Approach 2:
The getter material is deposited on the external STR region before the wafer bonding process. This preliminary placement of getter material in the external region prepares the system to handle outgassing during bonding, preventing contamination of the internal getter and maintaining vacuum integrity from the outset.
2Volume of moving object
If internal getter space is reduced due to smaller die sizes, then package size is reduced, but getter capacity decreases and vacuum maintenance becomes difficult
Solution Approach 1:
The invention utilizes the external STR region as an additional dimension for getter material placement. This external region serves as an extension of the internal getter space, effectively increasing the total getter capacity without increasing the internal package volume, thus maintaining small package size while compensating for reduced internal getter space.
Solution Approach 2:
The external getter layer in the STR region acts as an outer container or supplement to the internal getter. The external getter nested in the STR region provides additional pumping capacity that supports the internal getter, creating a nested getter system where the external layer compensates for the reduced internal space.
3Area of stationary object
If getter size is reduced, then package area is reduced, but the risk of contamination during bonding increases
Solution Approach 1:
By depositing getter material on the external STR region before bonding, the system prepares additional getter capacity in advance. This preliminary external getter layer is positioned to handle outgassing during the bonding process, preventing contamination of the internal getter and maintaining vacuum integrity without requiring larger internal getter area.
Solution Approach 2:
The external getter material in the STR region acts as an intermediary between the bonding environment and the internal getter. It serves as a first line of defense that absorbs outgassed contaminants during bonding, protecting the internal getter from contamination while maintaining the compact package area.
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
The external getter material absorbs outgassed impurities, reducing the load on internal getters and extending the life of the packaged devices by preserving vacuum conditions and improving pixel response.
Implementation Method 1
The getter absorbs, adsorbs, and/or physically entraps oxygen and other molecules and impurities that are outgassed from the components packaged within the WLP
Implementation Method 2
The getter absorbs, adsorbs, and/or physically entraps oxygen and other molecules and impurities that are outgassed from the components packaged within the WLP
Implementation Method 3
The getter is typically made from materials that react with the impurities to form stable compounds, such as oxides, carbides, hydrides, and nitrides
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
A system and method for forming a wafer level package. In one example, a substrate used in the wafer level package includes a surface defined by a wafer level package (WLP) region and an external region, and a layer of getter material is disposed on at least a portion of the external region. According to one embodiment, the external region comprises a saw-to-reveal (STR) region of the wafer.