Oxide-to-Oxide Bonding for Detector Bump Stress Relief
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Solution Overview
Problem
Conventional indium-to-indium cold-welding processes for bonding detectors to integrated chips require high external pressure, which can cause breakage and mechanical damage due to indium's weakness and the high forces applied.
Innovation Solution
A method involving a wafer with detector elements and bumps, where a polymer layer is formed between bumps, an oxide layer is deposited, vias are created in the oxide layer, and the polymer is removed to form a floating oxide layer, enabling an oxide-to-oxide bond between the detector elements and integrated chip without mechanical stress, using a process that aligns bumps and forms a structural and electrical connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If indium-to-indium cold-welding process is used to bond detectors to integrated chips, then a structural bond is formed, but high external pressure and force are required which cause breakage and mechanical damage to the detectors
Solution Approach 1:
The patent replaces the mechanical indium-to-indium cold-welding process with a chemical oxide-to-oxide bonding process. Detectors and integrated chips are coated with oxide layers (such as silicon dioxide) that form strong chemical bonds when brought into contact, eliminating the need for high mechanical pressure and force that cause indium bump breakage and detector damage
Solution Approach 2:
The patent changes the bonding mechanism from mechanical (cold-welding) to chemical (oxide bonding). By modifying the surface properties of the bumps through oxide coating and changing the bonding process parameters from high-pressure mechanical contact to low-pressure chemical reaction, the harmful mechanical stresses are eliminated while maintaining strong bond strength
2Reliability
If high external pressure is applied during indium-to-indium cold-welding, then bonding is achieved, but the weak indium material is subject to breakage
Solution Approach 1:
The patent substitutes the mechanical cold-welding process with chemical oxide bonding. The oxide layers on the detector bumps and integrated chip bumps form reliable chemical bonds without requiring high pressure, preventing indium bump breakage while ensuring bonding reliability
Solution Approach 2:
The oxide layer acts as an intermediary substance that enables bonding between the detector bumps and integrated chip bumps. Instead of directly bonding the weak indium to indium under high pressure, the oxide layers serve as intermediate bonding agents that form strong chemical bonds at much lower pressures, protecting the indium bumps from mechanical damage
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 method eliminates mechanical stress and damage by forming an oxide-to-oxide bond at lower pressures, ensuring a robust and reliable connection between detector elements and integrated chips without the need for high external forces, improving yield and reducing breakage risks.
Implementation Method 1
depositing an oxide layer on a top portion of each of the bumps and the polymer layer
Implementation Method 2
depositing an oxide layer on a top portion of each of the bumps and the polymer layer
Implementation Method 3
an oxide-to-oxide bond between the floating oxide layer and the oxide layer of the integrated chip, the oxide-to-oxide bond providing a structural bond between the detector elements and the integrated chip
Data Source
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AI summary
In one embodiment, a method of preparing detectors (220) for oxide bonding to an integrated chip (900), e.g., a readout integrated chip, includes providing a wafer having a plurality of detector elements with bumps (230) thereon. A floating oxide layer (810) is formed surrounding each of the bumps (230) at a top portion thereof. An oxide-to-oxide bond is formed between the floating oxide layer (810) and an oxide layer (910) of the integrated chip which is provided in between corresponding bumps (930) of the integrated chip. The oxide-to-oxide bond enables the bumps on the detector elements and the bumps on the integrated chip to be intimately contacted with each other, and removes essentially all mechanical stresses on and between the bumps. In another embodiment, a device has an interconnect interface that includes the oxide-to-oxide bond and an electrical connection between the bumps on the detector elements and the bumps on the integrated chip.