Method for etching mesa isolation in antimony-based compound semiconductor structures
View Patent ↗Antimony-based semiconductor devices are formed over a substrate structure ( 10 ) that includes an antimony-based buffer layer ( 24 ) and an antimony-based buffer cap ( 26 ). Multiple epitaxial layers ( 30–42 ) formed over the substrate structure ( 10 ) are dry etched to form device mesas ( 12 ) and the buffer cap ( 26 ) provides a desirably smooth mesa floor and electrical isolation around the mesas.
1. A method for etching mesa isolation in antimony-based compound semiconductor structures, the method comprising the steps of:
forming an antimony-based buffer layer;
forming an antimony-based buffer cap over the buffer layer;
forming a plurality of epitaxial layers over the buffer cap, the plurality of epitaxial layers including at least one antimony-based layer; and
removing defined portions of the plurality of epitaxial layers by dry etching to define at least one mesa structure;
wherein the antimony-based buffer cap provides electrical isolation around the mesa and a smooth mesa floor area.
2. A method as defined in claim 1 , wherein the first recited forming step forms the antimony-based buffer layer on a substrate.
3. A method as defined in claim 2 , wherein the substrate is a semiconductor substrate.
4. A method as defined in claim 2 , wherein the substrate is of a material selected from the group consisting of gallium arsenide (GaAs), indium phosphide (InP), gallium antimonide (GaSb), indium arsenide (InAs), zinc telluride (ZnTe), and cadmium selenide (CdSe).
5. A method as defined in claim 1 , wherein the antimony-based buffer layer contains aluminum (Al) and antimony (Sb).
6. A method as defined in claim 5 , wherein the antimony-based buffer layer is aluminum antimonide (AlSb).
7. A method as defined in claim 1 , wherein the antimony-based buffer cap is aluminum gallium antimonide.
8. A method as defined in claim 7 wherein the antimony-based buffer cap material is Al 0.7 Ga 0.3 Sb.
9. A method as defined in claim 1 , wherein the step of removing defined portions of the plurality of epitaxial layers comprises:
protecting a desired mesa region of the plurality of epitaxial layers with a patterned protective layer; and
dry etching unprotected regions around the desired mesa using a plasma system.
10. A method as defined in claim 9 , wherein the dry etching step uses an inductively coupled plasma etching system.
11. A method as defined in claim 9 , wherein the dry etching step uses an etching medium comprising a mixture of chlorine (Cl 2 ) and boron trichloride (BCl 3 ).
12. A method for etching mesa isolation in antimony-based compound semiconductor structures, the method comprising the steps of:
forming an antimony-based buffer layer;
forming an antimony-based buffer cap over the buffer layer;
forming at least one antimony-based epitaxial layer over the buffer cap; and
removing defined portions of the epitaxial layer to define at least one mesa structure;
wherein the antimony-based buffer cap provides electrical isolation around the mesa and a smooth mesa floor area.
13. A method as defined in claim 12 , wherein the first recited forming step forms the antimony-based buffer layer on a semiconductor substrate.
14. A method as defined in claim 13 , wherein the substrate is of a material selected from the group consisting of gallium arsenide (GaAs), indium phosphide (InP), gallium antimonide (GaSb), indium arsenide (InAs), zinc telluride (ZnTe), and cadmium selenide (CdSe).
15. A method as defined in claim 12 , wherein the antimony-based buffer layer is of aluminum antimonide (AlSb).
16. A method as defined in claim 12 , wherein the antimony-based buffer cap is aluminum gallium antimonide.
17. A method as defined in claim 16 wherein the antimony-based buffer cap material is Al 0.7 Ga 0.3 Sb.
18. A method as defined in claim 12 , wherein the step of removing defined portions of the at least one epitaxial layer comprises:
protecting a desired mesa region of the at least one epitaxial layer with a patterned protective layer; and
dry etching unprotected regions around the desired mesa using a plasma system.
19. A method as defined in claim 18 , wherein the dry etching step uses an inductively coupled plasma etching system.
20. A method as defined in claim 18 , wherein the dry etching step uses an etching medium comprising a mixture of chlorine (Cl 2 ) and boron trichloride (BCl 3 ).