UV-blocking layer for reducing UV-induced charging of SONOS dual-bit flash memory devices in BEOL processing
View Patent ↗A method of protecting a SONOS flash memory cell from UV-induced charging, including fabricating a SONOS flash memory cell in a semiconductor device; and depositing over the SONOS flash memory cell at least one UV-protective layer, the UV-protective layer including a substantially UV-opaque material. In one embodiment, the device includes a substantially UV-opaque sub-layer of a contact cap layer or a substantially UV-opaque contact cap layer.
1. A method of protecting a SONOS flash memory cell from UV-induced charging, comprising:
fabricating a SONOS flash memory cell in a semiconductor device; and
depositing over the SONOS flash memory cell at least one UV-protective layer, wherein the UV-protective layer comprises a substantially UV-opaque material,
wherein the UV-opaque material comprises one or more of silicon-rich silicon dioxide, silicon-rich silicon carbide or silicon-rich SiCN.
2. The method of claim 1 , wherein the UV-protective layer comprises either a sub-layer of a contact cap layer or a contact cap layer, disposed over the SONOS flash memory cell.
3. The method of claim 1 , wherein during BEOL processing in fabrication of the SONOS flash memory device, the device is exposed to UV radiation, and the UV-protective layer substantially protects the SONOS flash memory cell from damage resulting from the exposure to UV radiation.
4. The method of claim 1 , wherein the UV-opaque material further comprises silicon-rich silicon nitride.
5. The method of claim 1 , further comprising depositing at least one additional UV-protective layer, the at least one additional UV-protective layer comprising at least a sub-layer of a UV-opaque material.
6. The method of claim 5 , wherein the at least one additional UV-protective layer is a component of one or more of an interlayer dielectric layer 1 , interlayer dielectric layer 2 , or a top oxide layer.
7. The method of claim 1 , wherein the UV-opaque material comprises a refractive index greater than about 1.5.
8. The method of claim 7 , wherein the refractive index is in the range from about 1.55 to about 1.8.
9. The method of claim 1 , wherein the UV-protective layer is deposited by CVD, LPCVD or APCVD.
10. The method of claim 1 , further comprising depositing at least second and third UV-protective layers, each UV-protective layer comprising at least a sub-layer of a substantially UV-opaque material.
11. A method of protecting a SONOS flash memory cell from UV-induced charging, comprising:
fabricating a SONOS flash memory cell in a semiconductor device; and
depositing over the SONOS flash memory cell at least one UV-protective layer, wherein the UV-protective layer comprises a substantially UV-opaque material and either a sub-layer of a contact cap layer or a contact cap layer, disposed over the SONOS flash memory cell, and wherein the UV-opaque material comprises one or more of silicon-rich silicon dioxide, silicon-rich silicon carbide or silicon-rich SiCN.
12. The method of claim 11 , wherein during BEOL processing in fabrication of the SONOS flash memory device, the device is exposed to UV radiation, and the UV-protective layer substantially protects the SONOS flash memory cell from damage resulting from the exposure to UV radiation.
13. The method of claim 11 , wherein the UV-opaque material comprises a refractive index in the range from about 1.55 to about 1.8.
14. A method of protecting a SONOS flash memory cell from UV-induced charging, comprising:
fabricating a SONOS flash memory cell in a semiconductor device;
depositing over the SONOS flash memory cell at least one UV-protective layer, wherein the UV-protective layer comprises a substantially UV-opaque material and either a sub-layer of a contact cap layer or a contact cap layer, disposed over the SONOS flash memory cell; and
depositing at least one additional UV-protective layer, the at least one additional UV-protective layer comprising at least a sub-layer of a UV-opaque material,
wherein the UV-opaque material comprises one or more of silicon-rich silicon dioxide, silicon-rich silicon carbide or silicon-rich SiCN.
15. The method of claim 14 , wherein the at least one additional UV-protective layer is a component of one or more of an interlayer dielectric layer 1 , interlayer dielectric layer 2 , or a top oxide layer.
16. The method of claim 14 , further comprising depositing a third UV-protective layers, the third UV-protective layer comprising at least a sub-layer of a substantially UV-opaque material.
17. The method of claim 16 , wherein each additional UV-protective layer is a component of one or more of an interlayer dielectric layer 1 , interlayer dielectric layer 2 , or a top oxide layer.
18. The method of claim 14 , wherein during BEOL processing in fabrication of the SONOS flash memory device, the device is exposed to UV radiation, and the UV-protective layer substantially protects the SONOS flash memory cell from damage resulting from the exposure to UV radiation.
19. The method of claim 14 , wherein the UV-opaque material further comprises silicon-rich silicon nitride.
20. The method of claim 14 , wherein the UV-opaque material comprises a refractive index in the range from about 1.55 to about 1.8.