Method of protecting microfabricated devices with protective caps
View Patent ↗A method of using protective caps ( 160 ) applied to a first side of a wafer ( 150 ) in the production of microfabricated devices ( 152 ), such as micro-electro-mechanical systems (MEMS) devices. One cap ( 160 ) covers each microfabricated device or group respectively, such that a gap remains between adjacent protective caps. One or more etches are applied to the gaps between the caps to remove material and separate the wafer into separate units.
1. A method including:
a) providing a wafer having a plurality of microfabricated devices and a plurality of bond pads formed thereon;
b) applying a plurality of substantially hollow caps to a first side of the wafer, the caps positioned such that, in plan view, each cap overlays part or all of at least one microfabricated device and such that said bond pads are exposed;
c) applying a plurality of hollow caps to a second side of the wafer, the caps positioned such that, in plan view, the caps provide a mask to said bond pads; and
d) applying one or more etches to the wafer from the second side toward the first side to etch away at least some of the material between the peripheries of said caps to separate the wafer into separate units.
2. The method of claim 1 wherein each cap is joined to any adjacent cap by a thin layer of material extending between the periphery of each of the caps.
3. The method of claim 2 wherein the one or more etches are applied such that the layer of material adjoining adjacent caps is removed.
4. The method of claim 3 wherein the layer of material adjoining adjacent caps is removed by an oxygen etch.
5. The method of claim 1 wherein in plan view, each of the first plurality of caps overlays all or part of one or more microfabricated devices; and, in plan view, each of the second plurality of caps cover the corresponding first cap.