Method for producing electronic chips consisting of thinned silicon
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Abstract
The invention relates to the fabrication of color image sensors formed on a thinned silicon substrate.
The sensor is fabricated from a semiconductor wafer (10) comprising, on its front face, a thin active layer (12) of semiconductor material, and for this purpose etched layers are formed on the active layer, the wafer is bonded by its front face onto a support substrate (40), the semiconductor wafer is thinned down by its backside, then layers of material are deposited and etched on its backside thus thinned. Also provided are narrow vertical trenches (20, 22, 24, 26) that are etched into the wafer by its front face, before the bonding operation, these trenches extending into the wafer over a depth approximately equal to the residual semiconductor wafer thickness that will remain after the thinning operation, the trenches being filled with a conducting material isolated from the active layer and forming conducting vias (20′, 22′, 24′, 26′) between the front face and the backside of the thinned layer. The purpose of the trenches is to establish electrical connections between the front face and the backside of the thinned wafer. They can also serve as markers for alignment of the front-face features with those on the backside. Lastly, they can be used to electrically isolate regions of active layers from one another.
19 Citations
27 Claims
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1-15. -15. (canceled)
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16. A process for the fabrication of electronic chips from a semiconductor wafer comprising, on its front face, a thin active layer of semiconductor material, the process comprising steps of:
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formatting of etched layers on the active layer;
bonding the wafer by its front face onto a support substrate;
thinning down of the semiconductor wafer via its backside;
the depositing and etching of layers of material on its backside thus thinned, wherein narrow vertical trenches are etched into the wafer by its front face, before the bonding operation, these trenches extending into the wafer over a depth approximately equal to the residual semiconductor wafer thickness that will remain after the thinning operation, the trenches being filled with a conducting material isolated from the active layer and forming conducting vias between the front face and the backside of the thinned layer. - View Dependent Claims (17, 18, 19, 20, 21, 22, 24, 25)
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26. A color image sensor comprising
a support substrate, a thin silicon layer in which a matrix of photosensitive regions is formed, etched layers on a front face of this silicon layer, at least one metal layer and layers of color filters etched onto the other face, i.e. the backside, of the silicon layer, narrow vertical trenches traversing the whole of the silicon layer, having their sidewalls coated with an insulating layer and that are filled with a conducting material.
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27-1. The color image sensor as claimed in claim 27, comprising a series of parallel vertical trenches disposed under the same contact pad for the external connection of the image sensor and electrically connected to this pad.
Specification