Light emitting diodes (LEDs) with integrated CMOS circuits
Disclosed is a multi-color semiconductor LED display with integrated with CMOS circuit components, such as thin film transistors (TFTs). LEDs of the display are disposed on a first major surface of a substrate while CMOS circuit components which are configured as circuitry for operating the display are disposed on a second opposing major surface of the substrate. The CMOS components and LEDs are coupled by through silicon via (TSV) contacts through the substrate. Integrating CMOS components with LED on one substrate enhances compactness of the display. Other advantages include low power and low cost with high brightness and resolution desired for portable applications, including virtual reality and augmented reality applications.
1. A device comprising:
a substrate having first and second major substrate surfaces;
the first substrate surface comprises multiple quantum well (MQW) LEDs configured to form a multi-color LED display, wherein a MQW LED includes a first LED terminal and a second LED terminal;
complementary metal oxide semiconductor (CMOS) components disposed on the second substrate surface, wherein the CMOS components comprise low temperature CMOS components which avoid damaging the MQW LEDs on the first substrate surface;
CMOS back-end-of-line (BEOL) dielectric with a plurality of interlevel dielectric (ILD) layers to provide interconnections to the CMOS components; and
through silicon via (TSV) contacts which extend through the back surface of the substrate, wherein the TSV contacts
interconnect the CMOS components on the second substrate surface CMOS components to LED terminals on the first surface of the substrate, and
interconnect the external pad connections on the surface of the BEOL dielectric.
2. The device of claim 1 wherein the MQW LEDs comprise:
red (R) MQW LEDs;
green (G) MQW LEDs;
blue (B) MQW LEDs; and
wherein the R MQW LEDs, G MQW LEDs and B MQW LEDs are configured into a plurality of RGB pixels of the LED display.
3. The device of claim 2 wherein:
a MQW LED includes an LED body, the LED body serves as a first terminal of the MQW LED;
a MQW having alternating well and barrier layers, wherein a well layer comprises In x Ga 1-x N; and
a top LED layer, the top LED layer serving as the second terminal of the MQW LED;
wherein a RGB pixel includes a red (R) MQW LED, a green (G) MQW LED and a blue (B) MQW LED, wherein the MQW LED includes an anode terminal and a cathode terminal.
4. The device of claim 3 wherein
the R LEDs each includes a R MQW;
the G LEDs each includes a G MQW;
the B LEDs each includes a B MQW; and
wherein the R MQW, the G MQW and the B MQW comprise different bandgaps for emitting R, G and B light.
5. The device of claim 4 wherein the different bandgaps of the R MQW, the G MQW and B MQW are achieved by varying a percentage x of In in the well layers, wherein
the percentage x of In of the In x Ga 1-x N well layer of the R MQW is about 35-45%;
the percentage x of In of the In x Ga 1-x N well layer of the G MQW is about 25-30%; and
the percentage x of In of the In x Ga 1-x N well layer of the B MQW is about 15-20%.
6. The device of claim 3 wherein the MQW LEDs comprise fin-type MQW LEDs, wherein a fin-type LED comprises a fin LED body.
7. The device of claim 3 wherein the MQW LEDs comprise nanowire MQW LEDs, wherein a nanowire LED comprises a nanowire body.
8. The device of claim 1 wherein the low temperature CMOS components comprise thin film transistors.
9. The device of claim 1 wherein the CMOS components are configured to form circuitry to control the LEDs of the display.
10. The device of claim 1 wherein each TSV contact comprises a conductive contact surrounded by a dielectric collar.
11. The device of claim 1 wherein:
a first common terminal of the LEDs is disposed in an LED base layer above the first surface of the substrate;
second terminals of the LEDs are disposed in a metal level above the first common terminal of the LEDs; and
the TSV contacts comprise first and second TSV contacts, wherein
the first TSV contacts extend through the first substrate surface to the first common terminal of the LEDs, and
the second TSV contacts extend through the first substrate surface to the second terminals of the LEDs above the first common terminal.
12. A method of forming a device comprising:
providing a substrate, the substrate comprises first and second opposing major surfaces;
forming MQW LEDs on the first major surface of the substrate, the MQW LEDs are configured as a multi-color LED display;
forming CMOS components on the second major surface of the substrate using front-end-of-line (FEOL) processing;
forming back-end-of-line (BEOL) dielectric over the CMOS components using BEOL processing, the BEOL dielectric includes a plurality of interlevel dielectric (ILD) levels, wherein an ILD level comprises
a via dielectric layer with contacts,
a metal dielectric layer with metal lines, and wherein
the BEOL dielectric provides interconnections for the CMOS components;
forming through silicon via TSV contacts, the TSV contacts extend through the second substrate surface and connect to the LED terminals of the LED on the first substrate surface, wherein the TSV contacts provide interconnections between the CMOS components and LEDs.
13. The method of claim 12 wherein forming the MQW LEDs comprise:
forming red (R) MQW LEDs;
forming green (G) MQW LEDs;
forming blue (B) MQW LEDs; and
wherein the R MQW LEDs, G MQW LEDs and B MQW LEDs are configured into a plurality of RGB pixels of the LED display.
14. The method of claim 13 wherein:
a MQW LED includes an LED body, the LED body serves as a first terminal of the MQW LED;
a MQW having alternating well and barrier layers, wherein a well layer comprises In x Ga 1-x N ; and
a top LED layer, the top LED layer serving as the second terminal of the MQW LED. wherein a RGB pixel includes a red (R) MQW LED, a green (G) MQW LED and a blue (B) MQW LED, wherein the MQW LED includes an anode terminal and a cathode terminal.
15. The method of claim 14 wherein
the R LEDs each includes a R MQW;
the G LEDs each includes a G MQW;
the B LEDs each includes a B MQW; and
wherein the R MQW, the G MQW and the B MQW comprise different bandgaps for emitting R, G and B light.
16. The method of claim 15 wherein the different bandgaps of the R MQW, the G MQW and B MQW are achieved by varying a percentage x of In in the well layers, wherein
the percentage x of In of the In x Ga 1-x N well layer of the R MQW is about 35-45%;
the percentage x of In of the In x Ga 1-x N well layer of the G MQW is about 25-30%; and
the percentage x of In of the In x Ga 1-x N well layer of the B MQW is about 15-20%.
17. The method of claim 14 wherein forming the MQW LEDs comprises forming fin-type MQW LEDs, wherein a fin-type LED comprises a fin LED body.
18. The method of claim 14 wherein forming the MQW LEDs comprises forming nanowire MQW LEDs, wherein a nanowire LED comprises a nanowire body.
19. The method of claim 12 wherein forming the CMOS components comprises forming thin film transistors.
20. The method of claim 12 wherein each TSV contact comprises a conductive contact surrounded by a dielectric collar.