CMOS process polysilicon strip loaded waveguides with a two layer core
First Claim
1. An optical waveguide on a substrate, where the optical waveguide is comprised of:
- a core comprised of;
a slab of monocrystalline silicon, where the slab and a silicon body of a transistor are formed from the same layer of monocrystalline silicon on the same substrate, anda strip of polysilicon disposed on the slab of monocrystalline silicon, where the strip and a polysilicon gate for a transistor are formed at the same time from the same polysilicon, anda cladding comprised of a plurality of dielectric materials,where at least one of the plurality of dielectric materials is comprised of a salicide block layer used during the fabrication of a transistor.
7 Assignments
0 Petitions
Accused Products
Abstract
A standard CMOS process is used to fabricate optical, optoelectronic and electronic devices at the same time on a monolithic integrated circuit. A polysilicon strip loaded waveguide is used as an example to illustrate the invention. The waveguide has a two layer core made of a polysilicon strip on a silicon slab. In a standard CMOS process, a layer of metallic salicide is deposited for metallic contacts for electronic components, such as transistors. In the present invention, prior to the deposition of the salicide, a salicide blocking layer is selectively deposited for protecting silicon waveguide against damages. The salicide blocking layer is used as one layer of the cladding of a silicon waveguide.
27 Citations
19 Claims
-
1. An optical waveguide on a substrate, where the optical waveguide is comprised of:
-
a core comprised of; a slab of monocrystalline silicon, where the slab and a silicon body of a transistor are formed from the same layer of monocrystalline silicon on the same substrate, and a strip of polysilicon disposed on the slab of monocrystalline silicon, where the strip and a polysilicon gate for a transistor are formed at the same time from the same polysilicon, and a cladding comprised of a plurality of dielectric materials, where at least one of the plurality of dielectric materials is comprised of a salicide block layer used during the fabrication of a transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
a first layer comprised of monocrystalline silicon, a second layer comprised of silicon dioxide disposed on the first layer, a third layer comprised of monocrystalline silicon disposed on the second layer and a fourth layer comprised of silicon dioxide disposed on the third layer.
-
-
6. The optical waveguide of claim 5, wherein the cladding includes a bottom layer comprised of the fourth layer of the substrate, where the fourth layer is used to electrically isolate the transistor formed on the substrate from the third layer.
-
7. The optical waveguide of claim 1, wherein the substrate is comprised of sapphire.
-
8. The optical waveguide of claim 1, wherein the substrate is comprised of silicon on nothing, and the waveguide core is formed from a top layer of silicon.
-
9. The optical waveguide of claim 1, wherein the cladding includes a bottom cladding comprised of a top layer of the substrate.
-
10. The optical waveguide of claim 1, wherein the cladding includes a layer of dielectric material formed at the same time as a sidewall passivation for the silicon body of a transistor.
-
11. The optical waveguide of claim 1, wherein the cladding includes a plurality of layers of dielectric material formed at the same time as a plurality of dielectric materials used as a gate spacer for a transistor.
-
12. The optical waveguide of claim 1, wherein the cladding includes a layer of dielectric material formed at the same time as a contact punch-through layer for a transistor.
-
13. The optical waveguide of claim 1, wherein the cladding includes a layer of dielectric material formed at the same time as an inter-level dielectric for a transistor.
-
14. The optical waveguide of claims 10, 11, 12 or 13, wherein the layer of dielectric material included in the cladding is selected from the group comprising:
- silicon dioxide, silicon oxynitride or silicon nitride.
-
15. The optical waveguide of claim 1, wherein at least one of the plurality of dielectric materials is selected from a group of dielectrics used at the same time to form a dielectric element of a transistor, where the group of dielectrics comprises:
- a contact punch-through layer, an inter-layer dielectric film, a gate spacer, a salicide block, a dielectric spacer, a sidewall passivation film, an isolation dielectric, an oxide spacer and a field oxide.
-
16. The optical waveguide of claim 15, wherein thermal oxidation is used to form a sidewall passivation film, where the sidewall passivation film is used as one of a plurality of dielectric materials for the optical waveguide and is formed at the same time as the sidewall passivation film for the body of a transistor.
-
17. The optical waveguide of claim 1, wherein at least one of the plurality of dielectric materials is selected from the group comprising:
- SiO2, SiCOH, SiCOF, Si3N4, SiON, BPSG and silicon-based materials including one or more of the following elements;
oxygen, carbon, nitrogen, hydrogen, boron, phosphorus, fluorine and arsenic.
- SiO2, SiCOH, SiCOF, Si3N4, SiON, BPSG and silicon-based materials including one or more of the following elements;
-
18. The optical waveguide of claim 1, wherein the transistor is selected from the group comprising:
- a CMOS transistor, a BiCMOS transistor, a bipolar junction transistor (BJT) and a junction FET (JFET) transistor.
-
19. The optical waveguide of claim 1, wherein the salicide block layer is used as a gate spacer during the fabrication of a transistor on the same substrate.
Specification