Passivation for wafer level—chip-scale package devices
Aspects of the disclosure are directed towards an efficient wafer level chip-scale package, and methods or producing the packages. Various aspects are directed to protecting against humidity, contamination, mechanical damage, and current leakage while maintaining isolation and manufacturability of the plastic package and a ratio of active die size to package size.
1. A method comprising:
connecting a silicon wafer to a sawing foil;
dicing the silicon wafer and producing therefrom a plurality of self-contained chip-scale device packages in which each device package is separated from other ones of the device packages by a gap defined by sidewalls of the device packages, is connected to the sawing foil, and has an active side and a non-active side between which the sidewalls extend; and
while the device packages are coupled to a common foil, concurrently depositing an electrically isolating coating on the sidewalls and at least a portion of the non-active side of all of the plurality of device packages.
2. The method of claim 1 , wherein dicing the silicon wafer and producing therefrom a plurality of self-contained chip-scale device packages includes forming chip-scale device packages of different sizes and geometries.
3. The method of claim 1 , wherein
dicing the silicon wafer includes using a plasma to remove portions of the silicon wafer to form the gaps, and
depositing an electrically isolating coating on the sidewalls and the non-active sides includes depositing the coating from a plasma.
4. The method of claim 1 , wherein
dicing the silicon wafer includes using a plasma to remove portions of the silicon wafer to form the gaps, and
depositing an electrically isolating coating on the sidewalls and the non-active sides includes depositing the coating from the same plasma used to remove portions of the silicon wafer.
5. The method of claim 1 ,
further including providing an etch mask and etching a portion of the non-active side of the device packages under the mask, and
wherein depositing an electrically isolating coating includes depositing the electrically isolating coating on the sidewalls and the etched portion of the non-active side of the device packages.
6. The method of claim 5 , further including removing the etch mask after dicing the silicon wafer and prior to depositing an electrically isolating coating on a portion of the sidewalls of the device packages.
7. The method of claim 1 , wherein depositing an electrically isolating coating includes depositing the coating on the entire non-active side of the device packages.
8. The method of claim 1 , wherein
dicing the silicon wafer includes producing device packages being separated from other device packages by a distance less than 20 μm, and
depositing an electrically isolating coating includes depositing the coating at a thickness less than 1 μm.
9. The method of claim 1 , further including
forming pads on the active side at a first pitch,
connecting the device packages via the pads to PCB connectors having a second pitch different than first pitch; and
using the electrically isolating coating to mitigate current leakage between one of the PCB connectors and at least one of the sidewalls.
10. The method of claim 1 , wherein depositing an electrically isolating coating on the sidewalls and at least a portion of the non-active side includes depositing the electrically isolating coating using a plasma.
11. The method of claim 1 , wherein dicing the silicon wafer includes using a plasma to form a plurality of self-contained chip-scale device packages with non-rectangular edges.
12. A method comprising:
providing a wafer having an active side and a non-active side, the active side including a plurality of independently-operable integrated circuits each being separated from one another by separation regions within the wafer;
connecting the wafer to a sawing foil;
dicing the wafer at the separation regions and producing therefrom a plurality of self-contained chip-scale device packages having sidewalls defined by the dicing and remaining connected to the sawing foil, each device package including one of the plurality of integrated circuits and each device package being separated from other ones of the device packages by a gap defined by the sidewalls;
depositing an electrically isolating coating on the sidewalls and the non-active side of each of the plurality of device packages; and
after depositing the electrically isolating coating, separating the sawing foil from the device packages and attaching each of the device packages to a printed circuit board (PCB) via a solder bump.
13. The method of claim 12 , wherein providing a plurality of independently-operable integrated circuits includes providing independently-operable integrated circuits of different sizes and geometries, and producing a plurality of self-contained chip-scale device packages includes producing self-contained chip-scale device packages of different sizes and geometries.
14. The method of claim 12 , wherein the wafer is silicon and dicing the silicon wafer includes using a plasma to remove portions of the silicon wafer to form the gaps, and depositing an electrically isolating coating on the sidewalls and the non-active sides includes depositing the coating from the same plasma used to removed portions of the silicon wafer.
15. The method of claim 12 , wherein the wafer is silicon and dicing the silicon wafer includes using a plasma to remove portions of the silicon wafer to form the gaps and produce the self-contained chip-scale device packages having non-rectangular edges.
16. The method of claim 12 , wherein
dicing the wafer includes dicing the wafer with a plasma to form the devices with the gaps defined by sidewalls of adjacent self-contained chip-scale device packages being less than about 20 μm, and
depositing an electrically isolating coating includes depositing the coating using a plasma at thickness between approximately 0.1 μm and 1.0 μm.
17. The method of claim 12 , further including
forming pads on the PCB at a first pitch,
connecting the device packages to PCB connectors having a second pitch different than first pitch and
using the electrically isolating coating to mitigate current leakage between one of the PCB connectors and at least one of the sidewalls.
18. The method of claim 12 , wherein dicing the wafer at the separation regions and producing therefrom a plurality of self-contained chip-scale device packages includes producing the self-contained chip-scale device packages having sidewalls that extend at between the active side and the non-active side at an acute angle relative to a surface of one of the active and non-active sides.
19. An apparatus comprising:
a printed circuit board (PCB) having a first conductive contact at a surface of the PCB; and
a chip-scale device package connected to the PCB, the package including
a silicon wafer with an active side having an integrated circuit, a non-active side having bulk silicon, sidewalls extending between the active side and the non-active side, and a second conductive contact at a surface of the active side and connected to the first conductive contact, the second conductive contact being configured and arranged to electrically connect the integrated circuit to the PCB via the first conductive contact, with at least one of the sidewalls extending at an acute angle relative to a surface of one of the active and non-active sides and at least one edge between a sidewall and at least one of the active and non-active sides being non-rectangular, and
an electrically isolating plasma coating extending continuously along and in contact with one of sidewalls and the non-active side, the plasma coating being configured and arranged to mitigate current leakage between the sidewalls and the first conductive contact.