Making semiconductor devices with alignment bonding and substrate removal
View Patent ↗Embodiments include a manufacturing method of making a semiconductor device via multiple stages of alignment bonding and substrate removal. One example is an integrated full-color LED display panel, in which multiple wafers with different arrays of LEDs are integrated onto a host wafer with driver circuitry. The driver circuitry typically is an array of pixel drivers that drive individual LEDs on the display panel.
1. A method for fabricating an integrated LED display comprising:
fabricating a CMOS wafer comprising driver circuitry fabricated on a supporting substrate, the driver circuitry including an array of pixel drivers;
for each of two or more LED wafers, each LED wafer comprising an array of LEDs fabricated on a substrate, each LED having a first LED contact, wherein the two or more LED wafers comprise an LED wafer with red LEDs, an LED wafer with green LEDs and an LED wafer with blue LEDs:
bonding the LED wafer to the CMOS wafer, comprising aligning and bonding the first LED contacts to contacts for corresponding pixel drivers on the CMOS wafer; and
for all LED wafers except a last LED wafer, removing the substrate for the LED wafer before bonding the next LED wafer.
2. The method of claim 1 , wherein the integrated LED display is a multi-color LED display.
3. The method of claim 1 , wherein the integrated LED display is an RGB LED display; and the two or more LED wafers comprise a first LED wafer with LEDs used to produce red color pixels, a second LED wafer with LEDs used to produce green color pixels, and a third LED wafer with LEDs used to produce blue color pixels.
4. The method of claim 1 , wherein the substrates for the LED wafers are a different material than the supporting substrate.
5. The method of claim 1 , wherein the pixel drivers include driving transistors that drive the corresponding LEDs, and bonding the first LED contacts to contacts for corresponding pixel drivers on the CMOS wafer comprises bonding the first LED contacts to contacts for sources/drains of the driving transistors for the corresponding pixel drivers.
6. The method of claim 1 , wherein each LED has a second LED contact and bonding the LED wafer to the CMOS wafer further comprises bonding the second LED contacts to corresponding contacts on the CMOS wafer simultaneously with bonding the first LED contacts.
7. The method of claim 1 , wherein each LED has a second LED contact and the method further comprises:
after bonding of LED wafers to the CMOS wafer, making connections from the second LED contacts to corresponding contacts on the CMOS wafer.
8. The method of claim 1 , wherein removing the substrate for the LED wafer comprises removing the substrate via wet chemical etching.
9. The method of claim 1 , wherein removing the substrate for the LED wafer comprises removing the substrate via a laser lift off process.
10. The method of claim 1 , further comprising:
removing the substrate for the last LED wafer.
11. The method of claim 1 , wherein the substrate for the last LED wafer is not removed.
12. The method of claim 11 , wherein the substrate for the last LED wafer is transparent.
13. The method of claim 1 , further comprising:
after bonding of all LED wafers to the CMOS wafer, depositing a dielectric layer between the LEDs to electrically isolate the LEDs.
14. The method of claim 13 , further comprising:
planarizing the dielectric layer.
15. The method of claim 1 , wherein the pixel drivers comprise thin-film transistor pixel drivers.
16. The method of claim 1 , wherein the LED wafers are bonded to the CMOS wafer in the following order: first the red LED wafer, then the green LED wafer, and then the blue LED wafer.