Package for an electronic device
View Patent ↗A method of forming a device is provided. A substrate having a component is provided and a sacrificial layer is formed over the component. The sacrificial layer includes a cavity portion disposed about the component and a tunnel portion adjacent to the cavity portion. In addition, an encapsulation layer having a cover portion and a perimeter portion is formed over the sacrificial layer. The cover portion encapsulates the cavity portion such that the cavity portion forms a cavity within the cover portion. The perimeter portion is disposed over the tunnel portion. Moreover, an access hole is formed in the perimeter portion of the encapsulation layer.
1. A method of forming a device comprising:
providing a substrate having a component;
forming a sacrificial layer over the component, the sacrificial layer including a cavity portion at least partially surrounding the component and a tunnel portion adjacent the cavity portion;
forming an encapsulation layer having a cover portion and a perimeter portion over the sacrificial layer, wherein the cover portion encapsulates the cavity portion such that the cavity portion forms a cavity within the cover portion and the perimeter portion is disposed over the tunnel portion; and
forming an access hole in the perimeter portion of the encapsulation layer, wherein the tunnel portion is formed from a different material than the cavity portion.
2. The method of claim 1 , further comprising etching the tunnel portion via the access hole to form a tunnel extending to the cavity portion.
3. The method of claim 2 , wherein the cavity portion forms an etch stop, such that the etch stop prevents etching of the component during etching of the tunnel portion.
4. The method of claim 2 , wherein the tunnel portion comprises gold.
5. The method of claim 2 , further comprising etching the cavity portion via the access hole and the tunnel.
6. The method of claim 1 , further comprising etching the tunnel portion and the cavity portion via the access hole using a single etching process.
7. The method of claim 1 , further comprising:
etching the tunnel portion via the access hole with a first etchant during a first etching process to form a tunnel; and
etching the cavity portion via the access hole and the tunnel with a second etchant during a second etching process, thereby forming the cavity.
8. The method of claim 1 , wherein the cavity portion and the tunnel portion are formed from the same material, such that an etchant used to etch the tunnel portion also etches the cavity portion.
9. The method of claim 1 , wherein the access hole is formed over a portion of the tunnel portion.
10. The method of claim 1 , wherein the access hole has a slit, circular, oval, rectangular, or polygonal configuration.
11. The method of claim 1 , further comprising forming a second encapsulation layer over the encapsulation layer, wherein the second encapsulation layer seals the access hole.
12. The method of claim 1 , further comprising forming a first layer over the substrate, wherein a first portion of the first layer forms a portion of the component.
13. The method of claim 12 , wherein a second portion of the first layer forms the tunnel portion.
14. The method of claim 12 , further comprising forming a second layer over the substrate, wherein a portion of the second layer forms the tunnel portion.
15. The method of claim 12 , wherein the component is a Microelectromechanical Systems (MEMS) device and the first portion of the first layer forms a MEMS pad of the MEMS device.
16. The method of claim 12 , wherein the first portion of the first layer forms a contact pad of the component.
17. The method of claim 1 , wherein the tunnel portion includes a first layer and a second layer, where the first layer is etched to form a tunnel extending to the cavity portion.