Thermal isolation microstructure

Claim 2

A process for fabricating a thermal isolation microbridge used as an infrared radiation detection element, the steps comprising: providing a monocrystalline silicon substrate wafer having a planar surface; depositing a thin film silicon nitride layer on said surface; depositing and delineating a thin film layer of temperature-sensitive, electrically-resistive material for a sensor and electrode leadout on said silicon nitride layer; depositing a further thin film silicon nitride layer over said material and said first silicon nitride layer; depositing a thin absorber layer over the last deposited silicon nitride in the area of the sensor; depositing and delineating a thin film photo-lithographic mask; making a plurality of silicon nitride cuts outlining the elongated legs containing the electrode leadout and the support tabs for the microbridge; dry etching the legs and the support tabs to remove about 1/2 the thickness of silicon nitride; introducing anisotropic etchant through said cuts and anisotropically etching away silicon to form a pit beneath the microbridge sensor and legs; removing the thin film photolithographic mask with a liquid etch; etching with a plasma dry etch the exposed silicon nitride on said elongated legs to remove the Si 3 N 4 down to the electrode leadouts, which act as an etch stop to the dry etch, the plasma dry etch also removing the Si 3 N 4 of the leg extending laterally of the electrode.

Claim 3

The process according to claim 1 and directly following said step "depositing a thin absorber layer over the lest deposited silicon nitride in the area of the sensor", further comprising the step: covering said absorber layer with a thin film layer of silicon nitride.

Claim 4

The process according to claim 1 in which said temperature sensitive electrically-resistive material is nickel-iron.

Claim 5

The process according to claim 1 in which said absorber layer is a thin film layer of nickel-iron.

Claim 6

The process according to claim 1 in which said photolithographic mask is chrome metal.

Claim 7

A process for fabricating a thermal isolation microbridge used as an infrared radiation detection element, the steps comprising: providing a monocrystalline silicon substrate wafer having a planar surface depositing a thin film silicon nitride layer on said surface; depositing and delineating a thin film layer of nickel-iron for a sensor and leadout on said silicon nitride layer; depositing a further thin film silicon nitride layer over said material and said first silicon nitride layer; depositing a thin film absorber layer of nickel-iron over the last deposited silicon nitride in the area of the nickel-iron sensor; covering said absorber layer with a thin film layer of silicon nitride; depositing and delineating a thin film chrome metal mask; making a plurality of silicon nitride cuts outlining the elongated legs containing the nickel-iron leadout and the support tabs for the microbridge; dry etching the legs and the support tabs to remove about 1/2 the thickness of silicon nitride; introducing anisotropic etchant through said cuts and anisotropically etching away silicon to form a pit beneath the microbridge sensor and legs; removing the thin film chrome layer with a liquid etch; etching with a plasma dry etch the exposed silicon nitride on said elongated legs to remove the Si 3 N 4 down to the NiFe leadout, which NiFe acts as an etch stop to the dry etch, the plasma dry etch also removing the Si 3 N 4 of the leg extending laterally of the NiFe.

Claim 8

A process for fabricating a thermal isolation microbridge used as an infrared radiation detection element, the steps comprising: providing a monocrystalline silicon substrate wafer having a planar surface depositing a thin film silicon nitride layer on said surface; depositing and delineating a thin film layer of nickel-iron for a sensor and leadout on said silicon nitride layer; depositing a further thin film silicon nitride layer over said material and said first silicon nitride layer; depositing a thin film absorber layer of nickel-iron over the last deposited silicon nitride in the area of the nickel-iron sensor; covering said absorber layer with a thin film layer of silicon nitride; depositing and delineating a thin film chrome metal mask; making a plurality of silicon nitride cuts outlining the elongated legs containing the nickel-iron leadout and the support tabs for the microbridge; dry etching the legs and the support tabs to remove about 1/2 the thickness of silicon nitride; introducing anisotropic etchant through said cuts and anisotropically etching away silicon to form a pit beneath the microbridge sensor and legs; removing the thin film chrome layer with a liquid etch; etching with a plasma dry etch the exposed silicon nitride on said elongated legs to remove the Si 3 N 4 down to the NiFe leadout, which NiFe acts as an etch stop to the dry etch, the plasma dry etch also removing the Si 3 N 4 of the leg extending laterally of the NiFe.