Optical Semiconductor Sealing via Two-Step Gas Exchange
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Solution Overview
Problem
The use of gold-tin as a sealing member in optical semiconductor devices can lead to oxidation when heated, reducing the reliability of the sealing process, while a gas atmosphere without oxygen may degrade the device, compromising its reliability.
Innovation Solution
A method involving a two-step gas exchange process where the optical semiconductor device is initially sealed in an atmosphere with high oxygen content, followed by a reduction in oxygen concentration to inhibit leakage and allow eutectic bonding of the gold-tin bonding member at a low oxygen concentration, preventing oxidation and ensuring reliable sealing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gold-tin is used as a sealing member and the atmosphere gas for sealing contains oxygen, then the sealing process can be performed, but the gold-tin alloy is oxidized when heated and melted, preventing reliable sealing
Solution Approach 1:
The patent applies preliminary action by placing the lid body on the package substrate in an oxygen-containing atmosphere before the bonding process, allowing oxygen to be trapped inside the sealed space. Then the atmosphere is exchanged to remove oxygen from outside before heating. This preliminary arrangement of oxygen distribution resolves the contradiction by ensuring oxygen is present where needed (inside the package) but absent where harmful (during bonding).
Solution Approach 2:
The patent implements local quality by creating different oxygen concentration zones: high oxygen concentration inside the package (to protect the semiconductor device) and low oxygen concentration outside the package (to prevent oxidation during bonding). This spatial differentiation of oxygen concentration allows both requirements to be satisfied simultaneously in different locations.
2Reliability
If the sealing gas does not contain oxygen, then oxidation of the bonding member is prevented, but the optical semiconductor device is likely to be degraded and reliability is lowered
Solution Approach 1:
The patent uses preliminary action by pre-placing the lid body in an oxygen-containing atmosphere before sealing, ensuring oxygen is trapped inside the package. This preliminary step guarantees the semiconductor device is exposed to oxygen before the atmosphere exchange occurs, protecting it from degradation while allowing subsequent oxidation-free bonding.
Solution Approach 2:
The patent applies local quality by maintaining high oxygen concentration inside the package (where the semiconductor device is located) and low oxygen concentration outside the package (where the bonding occurs). This localized oxygen distribution protects the device from degradation while preventing bonding member oxidation.
3Reliability
If oxygen concentration is reduced in the atmosphere during heating, then oxidation of the bonding member is prevented, but oxygen may leak outside the package reducing the oxygen environment needed for device protection
Solution Approach 1:
The patent applies preliminary action by placing the lid body on the substrate in an oxygen-containing atmosphere before bonding, pre-loading oxygen into the sealed space. This ensures sufficient oxygen is trapped inside before the atmosphere exchange and heating process begins, maintaining oxygen concentration despite the subsequent atmosphere change.
Solution Approach 2:
The patent implements local quality by creating a localized high-oxygen environment inside the package while maintaining low oxygen concentration outside. The temporary sealing structure confines oxygen to the internal space, allowing different oxygen concentrations in different locations without mutual interference.
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
This approach enhances the reliability of the optical semiconductor apparatus by preventing oxidation of the gold-tin bonding member and maintaining a suitable oxygen environment within the package, thereby extending the device's lifespan and improving sealing quality.
Implementation Method 1
heating and melting the bonding member after an exchange for the second gas is started so as to bond the package substrate and the lid body
Implementation Method 2
the gold-sin is oxidized when the gold-tin alloy is heated and melted
Data Source
Figure 1~2
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Figure 4
AI summary
A method of manufacturing an optical semiconductor apparatus 10 includes: placing a light transmissive lid body 40 on a package substrate 30 adapted to house an optical semiconductor device 20 in an atmosphere of a first gas containing oxygen (O2), sandwiching a bonding member 56 containing gold-tin (AuSn); exchanging an atmosphere gas for a second gas so as to reduce an oxygen concentration in the atmosphere while a load is exerted from above the lid body 40 placed on the package substrate 30 for temporary sealing; and heating and melting the bonding member 56 after an exchange for the second gas is started so as to bond the package substrate 30 and the lid body 40.