US 6,548,322 B1Granted

Micromachined gas-filled chambers and method of microfabrication

AssigneeInstrumentarium Corp.

InventorsGöran Stemme, Edvard Kälvesten

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Abstract

Micromachining, etching and bonding techniques are employed to fabricate hermetically sealed gas-filled chambers from silicon and/or glass wafers. The hermetically sealed gas-filled chambers have precise dimensions and are filled with a preselected concentration of gas, thus rendering exceptional performance for use as an optical gas filter. The first step involves etching one or more cavities or holes in one or more glass or silicon wafers. These wafers eventually become part of a chip assembly having one or more hermetically sealed gas-filled chambers after appropriate bonding procedures. Interfaces between aligned silicon wafers are bonded using fusion bonding techniques whereas interfaces between silicon and glass wafers are bonded using anodic bonding techniques. Bonding is accomplished in an over-pressured gas-filled bonding environment that contains a selected concentration of gas which is maintained at the bonding temperature in order to encapsulate a precise concentration of the gas within the micromachined cavity.

Claims35

Dependent claims

A single-chip, microfabricated assembly for presenting preselected optical transmission properties to electromagnetic radiation, said assembly comprising:

a substrate having a plurality of cavities etched therein such that a respective anodic bonding surface surrounds each cavity, said substrate being transmissive to electromagnetic radiation;
at least one cover bonded to the respective anodic bonding surfaces on the substrate to form a plurality of hermetically sealed gas-filled chambers in the assembly, said at least one cover being transmissive to electromagnetic radiation;
wherein each respective cover is bonded to the respective anodic bonding surface on the substrate by anodic bonding an enclosing wafer to the respective bonding surfaces on the substrate while the substrate with the plurality of etched cavities is located in a gas-filled anodic bonding environment containing a selected concentration of gas at an anodic bonding temperature Tab and pressure Pab, the gas being selected to have optical transmission characteristics suitable for providing the preselected optical transmission properties for electromagnetic radiation, each respective anodic bond being implemented by aligning the enclosing wafer against the anodic bonding surfaces for the respective cavities in the substrate to form a bonding interface between the enclosing wafer and the respective bonding surface on the substrate, contemporaneously capturing the selected concentration of gas within the respective cavity to establish, from the optical transmission characteristics of the gas, the preselected optical transmission properties for electromagnetic radiation passing through the respective cavity, and thereafter applying an anodic bonding voltage across the respective bonding interface while the enclosing wafer and the substrate are located in the gas-filed environment at the anodic bonding temperature Tab and pressure Pab to bond the respective interface and hermetically seal the respective cavities with the selected concentration of gas therein.

A single-chip, microfabricated assembly for presenting preselected optical transmission properties to electromagnetic radiation, said assembly comprising:

a silicon substrate having a plurality of cavities etched therein such that a respective bonding surface surrounds each cavity, said substrate being transmissive to electromagnetic radiation;
at least one silicon cover bonded to the respective bonding surfaces on the silicon substrate to form a plurality of hermetically sealed gas-filled chambers in the assembly, said at least one cover being transmissive to electromagnetic radiation;
wherein each respective silicon cover is bonded to the respective bonding surface on the silicon substrate in the following manner:
the silicon surfaces are prepared for fusion bonding;
the silicon substrate and silicon cover are placed within a gas-filled bonding environment, the gas-filled bonding environment containing a selected concentration of gas at a selected pressure, the gas being selected to have optical transmission characteristics suitable for providing the preselected optical transmission properties for electromagnetic radiation;
the silicon substrate and silicon cover are initially bonded together while the silicon substrate and cover are located in the gas-filled bonding environment by aligning and engaging the respective bonding surfaces on the respective silicon substrate and cover to form a bonding interface therebetween while contemporaneously capturing the selected concentration of the gas from the gas-filled bonding environment within the respective cavities to establish, from the optical characteristics of the gas, the preselected optical transmission properties for electromagnetic radiation;
and
a sufficient amount of thermal energy is thereafter applied for a sufficient amount of time to strengthen the initial bonds and hermetically seal the respective chambers with the selected concentration of gas therein.

5 more elements

Dependencies are inferred from the claim text.