Method for fabricating package structures for optoelectronic devices
A package structure for an optoelectronic device. The package structure comprises a device chip reversely disposed on a first substrate, which comprises a second substrate and a first dielectric layer between the first and second substrates. The first dielectric layer comprises a pad formed in a corner of the first dielectric layer non-overlapping the second substrate, such that the surface and sidewall of the pad are exposed. A metal layer is formed directly on the exposed surface of the pad and covers the second substrate. A protective layer covers the metal layer, having an opening to expose a portion of the metal layer on the second substrate. A solder ball is disposed in the opening, electrically connecting to the metal layer. The invention also discloses a method for fabricating the same.
1. A method for fabricating package structures for optoelectronic devices, comprising:
reversely placing a device wafer on a first substrate, wherein the device wafer comprises:
a second substrate; and
a first dielectric layer between the first and second substrates, comprising at least one pair of pads formed in the first dielectric layer;
forming a first opening in the second substrate and the first dielectric layer to expose the surface and sidewall of the pair of pads;
forming a metal layer directly on the exposed surface of each pad and covering the second substrate;
forming a protective layer on the metal layer and filling the first opening in the first dielectric layer;
forming at least one second opening in the protective layer, corresponding to each pad and exposing a portion of the metal layer on the second substrate;
forming a solder ball in the second opening, electrically connecting to the metal layer; and
dicing the device wafer and the first substrate along the first opening in the first dielectric layer.
2. The method as claimed in claim 1 , further forming a second dielectric layer between the second substrate and the metal layer.
3. The method as claimed in claim 1 , further forming a dam between the first substrate and the first dielectric layer to form a cavity therebetween.
4. The method as claimed in claim 1 , further forming a glue layer between the first substrate and the first dielectric layer.
5. The method as claimed in claim 1 , wherein the first substrate comprises glass and the second substrate comprises silicon.
6. A method for fabricating package structures for optoelectronic devices, comprising:
placing a device wafer between first and second substrates, comprising:
a third substrate adjacent to the first substrate; and
a first dielectric layer between the second and third substrates, comprising at least one pair of pads formed in the first dielectric layer;
forming a first opening in the second substrate and the first dielectric layer to expose the surface and sidewall of the pair of pads;
forming a metal layer directly on the exposed surface of each pad and covering the second substrate;
forming a protective layer on the metal layer and filling the first opening in the first dielectric layer;
forming at least one second opening in the protective layer, corresponding to each pad and exposing a portion of the metal layer on the second substrate;
forming a solder ball in the second opening, electrically connecting to the metal layer; and
dicing the device wafer and the first substrate along the first opening in the first dielectric layer.
7. The method as claimed in claim 6 , further forming a second dielectric layer between the second substrate and the metal layer.
8. The method as claimed in claim 6 , further forming a dam between the first and third substrates to form a cavity therebetween.
9. The method as claimed in claim 6 , further forming a glue layer between the first and third substrates.
10. The method as claimed in claim 6 , wherein the first substrate comprises glass and the second and third substrates comprises silicon.