Getter Material Detachment in Micromechanical Direct Bonding
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Solution Overview
Problem
Current getter materials used in micromechanical devices are not capable of withstanding the thermal treatments required for direct bonding, leading to loss of gas sorption ability and potential contamination of functional parts.
Innovation Solution
A process involving the formation of an intermediate vitreous, ceramic, or oxidic layer on the silicon support with a getter material layer containing zirconium and elements like molybdenum, niobium, or tungsten, where the getter material is deposited using sputtering techniques to prevent detachment during direct bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If getter material is deposited directly on silicon support, then manufacturing simplicity is improved, but thermal treatment during direct bonding causes loss of gas sorption ability
Solution Approach 1:
A thin protective layer of silicon oxide or silicon nitride is deposited as an intermediate barrier between the silicon wafer and the getter material. This adds one more deposition step but prevents the catastrophic loss of getter material functionality, making the overall process more reliable despite the slight increase in manufacturing complexity.
2Strength
If high temperature thermal treatment is applied for direct bonding, then bonding strength is improved, but getter material undergoes structural rearrangement and melting
Solution Approach 1:
The protective layer of silicon oxide or silicon nitride serves as a thermal barrier and physical separator during high-temperature direct bonding. It allows the bonding process to proceed at high temperatures to achieve strong bonding between silicon and the device structure, while the getter material remains protected from direct thermal exposure and structural degradation.
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
Prevents getter material detachment and maintains gas sorption ability, ensuring the reliability and durability of micromechanical devices by using specific getter materials and layer thicknesses in the direct bonding process.
Implementation Method 1
a getter material, that is, a material capable of removing most non-noble gases
Implementation Method 2
The preferred technique for the deposition of getter material layers in this application is cathodic deposition, commonly known as 'sputtering.' By applying a potential difference of the magnitude of thousands of volts (or lower, depending on the configuration used) between the target (held at cathodic potential) and an anode, the noble gas is ionized and the ions so produced are accelerated towards the target, thus eroding it by impact. The eroded material deposits on the available surfaces, including the support.
Implementation Method 3
the invention relates to a process for manufacturing the devices comprising a step of joining together two wafers by melting at the interface therebetween
Data Source
AI summary
A process is provided for manufacturing micromechanical devices formed by joining two parts together by direct bonding. One of the parts (12) is made of silicon and the other one is made of a material chosen between silicon and a semiconductor ceramic or oxidic material. The joint between the two parts forms a cavity (14) containing the functional elements of the device (11), possible auxiliary elements and a getter material deposit (13).