Process methodology for two-sided fabrication of devices on thinned silicon

Claim 1

A method of forming a detector device having a thinned region from a semiconductor substrate of larger thickness defined by first and second major surfaces, said method comprising the steps of: (a) forming a cavity in the substrate substrate to provide a thinned region therein having a third surface generally parallel to the first surface; (b) implanting ions to form implanted layers of a given dopant concentration on the first, second and third surfaces; (c) annealing the substrate and implanted layers; (d) depositing metal onto the implanted layers of the first, second and third surfaces; (e) selectively removing metal and portions of the implanted layer to form a plurality of contacts on the first surface; (f) selectively removing metal from the third surface in areas opposite the contacts to form a light shield in the areas between the contacts; and (g) separating the thinned region from the substrate whereby the processing of the thinned region can easily be performed on two sides prior to mounting it to a readout device.

Claim 2

A method of forming a detector device having a thinned region from a semiconductor substrate of larger thickness defined by first and second major surfaces, said method comprising the steps of: (a) forming a cavity in the substrate substrate to provide a thinned region therein having a third surface generally parallel to the first surface; (b) implanting ions to form implanted layers of a given dopant concentration on the first, second and third surfaces; (c) annealing the substrate and implanted layers; (d) depositing metal onto the implanted layers of the first, second and third surfaces; (e) selectively removing metal and portions of the implanted layer to form a plurality of contacts on the first surface; (f) selectively removing metal from the third surface in areas opposite the contacts to form a light shield in the areas between the contacts; and (g) separating the thinned region from the substrate whereby the processing of the thinned region can easily be performed on two sides prior to mounting it to a readout device.

Claim 7

A method for two-sided fabrication of infrared detector devices on a silicon substrate, said method comprising the steps of: (a) growing an epitaxial layer on a first surface of the substrate, said epitaxial layer having a different dopant concentration than the substrate; (b) thermally oxidizing the substrate to form oxide layers on the first surface and an opposite second surface of the substrate; (c) coating the oxide layers with a maskant layer of silicon nitride; (d) photolithographically opening a window in the maskant on the second surface; (e) etching the substrate through the window to form a third surface parallel to the first surface and spaced therefrom by a given distance thereby forming a thinned region for use as the detector; (f) removing the maskant; (g) implanting ions to form implanted layers of a given dopant concentration on the first, second and third surfaces; (h) annealing the substrate and implanted layers; (i) depositing aluminum onto the implanted layers of the first, second and third surfaces; (j) selectively removing portions of the implanted layer and aluminum to form a plurality of contacts on the first surface opposite the third surface; (k) selectively removing aluminum from the third surface in areas opposite the contacts to form a light shield in the areas between the contacts; (k) applying adhesive into the cavity defined by the area between the second and third surfaces and onto the second surface; (l) attaching a backing wafer to the second surface; (m) forming indium bumps on the contacts; (n) separating the thinned region from its adjacent thicker substrate to form individual chips of the thinned region containing the contacts and light shield; (o) removing the adhesive and backing wafer; and (p) attaching the chip to a readout device whereby the processing of the thinned device can easily be performed on two sides prior to mounting it to the readout device.

Claim 8

A method for two-sided fabrication of infrared detector devices on a silicon substrate, said method comprising the steps of: (a) growing an epitaxial layer on a first surface of the substrate, said epitaxial layer having a different dopant concentration than the substrate; (b) thermally oxidizing the substrate to form oxide layers on the first surface and an opposite second surface of the substrate; (c) coating the oxide layers with a maskant layer of silicon nitride; (d) photolithographically opening a window in the maskant on the second surface; (e) etching the substrate through the window to form a third surface parallel to the first surface and spaced therefrom by a given distance thereby forming a thinned region for use as the detector; (f) removing the maskant; (g) implanting ions to form implanted layers of a given dopant concentration on the first, second and third surfaces; (h) annealing the substrate and implanted layers; (i) depositing aluminum onto the implanted layers of the first, second and third surfaces; (j) selectively removing portions of the implanted layer and aluminum to form a plurality of contacts on the first surface opposite the third surface; (k) selectively removing aluminum from the third surface in areas opposite the contacts to form a light shield in the areas between the contacts; (k) applying adhesive into the cavity defined by the area between the second and third surfaces and onto the second surface; (l) attaching a backing wafer to the second surface; (m) forming indium bumps on the contacts; (n) separating the thinned region from its adjacent thicker substrate to form individual chips of the thinned region containing the contacts and light shield; (o) removing the adhesive and backing wafer; and (p) attaching the chip to a readout device whereby the processing of the thinned device can easily be performed on two sides prior to mounting it to the readout device.