US 6,124,145 AGranted

Micromachined gas-filled chambers and method of microfabrication

AssigneeInstrumentarium Corp.

InventorsGoran Stemme, Edvard Kalvesten

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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.

Claims46

Dependent claims

A method of microfabricating a hermetically sealed gas-filled chamber which contains a gas having a preselected concentration such that the pressure within the chamber is equal to a preselected value P.sub.c when the temperature of the chamber is at a preselected temperature T.sub.0, the gas-filled chamber being microfabricated from a silicon substrate comprising one or more silicon wafers, and a glass wafer bonded to the silicon substrate such that a gas-filled cavity is located adjacent the interface between the silicon substrate and the glass wafer, the method of microfabricating the gas-filled chamber comprising:

etching a cavity in the silicon substrate, the cavity being adjacent and surrounded by an anodic bonding surface on the silicon substrate;
placing the silicon substrate with the etched cavity within a gas-filled anodic bonding environment, the gas-filled anodic bonding environment containing a concentration of gas substantially maintained at an anodic bonding temperature T.sub.ab and an anodic bonding pressure P.sub.ab, wherein said bonding pressure P.sub.ab is substantially equal to P.sub.ab =P.sub.c (T.sub.ab /T.sub.0) where T.sub.ab and T.sub.0 are absolute temperature values and P.sub.ab and P.sub.c are absolute pressure values and P.sub.c is the preselected pressure value within the chamber when the chamber is at the preselected temperature T.sub.0 ;
and
anodic bonding the glass wafer to the anodic bonding surface on the silicon substrate while the silicon substrate with the etched cavity is located within the gas-filled anodic bonding environment at temperature T.sub.ab and pressure P.sub.ab, the anodic bonding in the gas-filled anodic bonding environment being implemented by aligning the glass wafer with the bonding surface of the silicon substrate to form a bonding interface between the glass wafer and the silicon substrate and contemporaneously capturing gas from the gas-filled anodic bonding environment within the cavity, and thereafter applying a bonding voltage across the bonding interface between the glass wafer and the silicon substrate while the glass wafer and the silicon substrate are aligned for bonding within the gas-filled anodic bonding environment to bond the interface and hermetically seal the selected concentration of gas therein.

1 more element

A method of microfabricating a hermetically sealed gas-filled chamber which contains a gas having a preselected concentration such that the pressure within the chamber is equal to a preselected value P.sub.c when the temperature of the chamber is at a preselected temperature T.sub.0, the gas-filled chamber being microfabricated from a plurality of silicon and/or glass wafers such that a gas-filled cavity is located adjacent an interface between at least two of the wafers, the method of microfabricating the gas-filled chamber comprising:

etching a cavity in a first substrate made from one or more wafers, the cavity being adjacent and surrounded by an anodic bonding surface on the substrate;
placing the substrate with the etched cavity within a gas-filled anodic bonding environment, the gas-filled anodic bonding environment containing a concentration of gas substantially maintained at an anodic bonding temperature T.sub.ab and an anodic bonding pressure P.sub.ab wherein said bonding pressure P.sub.ab is substantially equal to P.sub.ab =P.sub.c (T.sub.ab /T.sub.0) where T.sub.ab and T.sub.0 are absolute temperature values and P.sub.ab and P.sub.c are absolute pressure values and P.sub.c is the preselected pressure value within the chamber when the chamber is at the preselected temperature T.sub.0 ;
and
anodic bonding an enclosing wafer to the anodic bonding surface on the substrate while the substrate with the etched cavity is located within the gas-filled anodic bonding environment at temperature T.sub.ab and pressure P.sub.ab, the anodic bonding in the gas-filled anodic bonding environment being implemented by aligning the enclosing wafer with the bonding surface of the substrate to form a bonding interface between the enclosing wafer and the substrate, contemporaneously capturing gas from the gas-filled anodic bonding environment within the cavity, and thereafter applying a bonding voltage across the bonding interface between the enclosing wafer and the substrate while the enclosing wafer and the substrate are aligned for bonding within the gas-filled anodic bonding environment to bond the interface and hermetically seal the selected concentration of gas therein.

1 more element

A method of microfabricating a hermetically sealed gas-filled chamber which contains a gas having a preselected concentration such that the pressure within the chamber is equal to a preselected value P.sub.c when the temperature of the chamber is at a preselected temperature T.sub.0, the gas-filled chamber being microfabricated from two or more silicon wafers such that a gas-filled cavity is located adjacent the interface between two of the silicon wafers, the method of microfabricating the gas-filled chamber comprising the steps of:

etching a cavity in at least one of the silicon wafers, the cavity being adjacent and surrounded by a fusion bonding surface on the etched silicon wafer;
preparing the surfaces of the silicon wafers for fusion bonding;
placing the silicon wafers within a gas-filled bonding environment, the gas-filled fusion bonding environment comprising a concentration of a selected gas at a selected pressure;
initially bonding the silicon wafers together while the silicon wafers are located in the gas-filled bonding environment by aligning and engaging the respective fusion bonding surfaces on the respective silicon wafers to form a bonding interface therebetween while contemporaneously capturing the gas from the gas-filled bonding environment within the cavity;
and
thereafter applying a sufficient amount of thermal energy for a sufficient amount of time to strengthen the initial bonds and hermetically seal the chamber with the selected concentration of gas therein.

3 more elements

Dependencies are inferred from the claim text.