Method of housing an infrared radiation micro unit (120,121) to provide an infrared radiation micro device on wafer level, a housing comprising a cover and a substrate and a silicon distance frame, the method comprising the following steps - masking the cover with a pattern to form a surface texture (191,196) reducing an effective refractive index of the cover; - etching the cover to create an area (190,195) with the surface texture comprising elevations and/or depressions (191,196) that reduce the effective refractive index of the cover in the area (190,195); - providing the silicon distance frame on a substrate side of the cover, wherein the silicon distance frame is provided by -- depositing an unstructured TEOS (tetraethyl orthosilicate) layer on the complete cover comprising the surface texture (191,196) thus also covering the area (190,195) of reduced effective refractive index, -- depositing by CVD a silicon layer on the unstructured TEOS layer, -- masking the CVD deposited silicon layer with a pattern that defines the silicon distance frame, -- etching the CVD deposited silicon layer to provide the silicon distance frame, and -- removing, outside the silicon distance frame, the unstructured TEOS layer from the cover to expose the surface texture (191,196) having reduced effective refractive index; - bonding of substrate and cover (101,102) holding the silicon distance frame, whereby substrate, cover and intermediate distance frame form a cavity, housing the infrared radiation micro unit (120,121) on the substrate. - masking the cover with a pattern to form a surface texture (191,196) reducing an effective refractive index of the cover; - etching the cover to create an area (190,195) with the surface texture comprising elevations and/or depressions (191,196) that reduce the effective refractive index of the cover in the area (190,195); - providing the silicon distance frame on a substrate side of the cover, wherein the silicon distance frame is provided by -- depositing an unstructured TEOS (tetraethyl orthosilicate) layer on the complete cover comprising the surface texture (191,196) thus also covering the area (190,195) of reduced effective refractive index, -- depositing by CVD a silicon layer on the unstructured TEOS layer, -- masking the CVD deposited silicon layer with a pattern that defines the silicon distance frame, -- etching the CVD deposited silicon layer to provide the silicon distance frame, and -- removing, outside the silicon distance frame, the unstructured TEOS layer from the cover to expose the surface texture (191,196) having reduced effective refractive index; -- depositing an unstructured TEOS (tetraethyl orthosilicate) layer on the complete cover comprising the surface texture (191,196) thus also covering the area (190,195) of reduced effective refractive index, -- depositing by CVD a silicon layer on the unstructured TEOS layer, -- masking the CVD deposited silicon layer with a pattern that defines the silicon distance frame, -- etching the CVD deposited silicon layer to provide the silicon distance frame, and -- removing, outside the silicon distance frame, the unstructured TEOS layer from the cover to expose the surface texture (191,196) having reduced effective refractive index; - bonding of substrate and cover (101,102) holding the silicon distance frame, whereby substrate, cover and intermediate distance frame form a cavity, housing the infrared radiation micro unit (120,121) on the substrate.