METHODS OF FORMING SEMICONDUCTOR STRUCTURES AND RESULTING SEMICONDUCTOR STRUCTURES
A method of forming a semiconductor structure includes forming an epitaxial semiconductor island having a first material characteristic on a base layer, and growing an epitaxial structure from the epitaxial semiconductor island and the base layer. The epitaxial structure has a second material characteristic that is different from the first material characteristic of the epitaxial semiconductor island. Related semiconductor device structures are also disclosed.
1 . A method of forming a semiconductor structure, comprising:
forming an epitaxial semiconductor island comprising a first material characteristic on a substrate; and
growing an epitaxial structure from the epitaxial semiconductor island and the substrate, wherein the epitaxial structure comprises a second material characteristic that is different from the first material characteristic of the epitaxial semiconductor island;
wherein the epitaxial semiconductor island extends to, contacts, or forms a part of, an active region of the semiconductor structure.
2 . The method of claim 1 , further comprising:
forming an ohmic contact on the epitaxial semiconductor island.
3 - 11 . (canceled)
12 . The method of claim 1 , wherein the epitaxial structure comprises a high electron mobility transistor device structure having a channel layer and a barrier layer on the channel layer, wherein the barrier layer has a higher bandgap than the channel layer, such that a two-dimensional electron gas, 2DEG, is formed at an interface between the channel layer and the barrier layer.
13 . The method of claim 12 , wherein the epitaxial semiconductor island comprises a mesa that extends above the substrate, and wherein the 2DEG has a curvature such that the 2DEG extends up a sidewall of the mesa.
14 . The method of claim 1 , wherein forming the epitaxial semiconductor islands comprises:
forming a mask on the substrate;
forming an opening in the mask to expose a region of the substrate, wherein the epitaxial semiconductor island is formed in the opening; and
removing the mask after forming the epitaxial semiconductor island.
15 . The method of claim 14 , further comprising, after forming the opening in the mask, etching the substrate through the opening in the mask to form a trench in the substrate, wherein the epitaxial semiconductor island is at least partially formed in the trench.
16 - 19 . (canceled)
20 . The method of claim 1 , further comprising:
selectively etching the epitaxial structure to expose the epitaxial semiconductor island; and
forming an ohmic contact on the exposed epitaxial semiconductor island.
21 . The method of claim 20 , wherein selectively etching the epitaxial structure to expose the epitaxial semiconductor island comprises:
forming an etch mask on the epitaxial structure having an opening therein above the epitaxial semiconductor island; and
etching the epitaxial structure through the opening in the etch mask.
22 - 25 . (canceled)
26 . The method of claim 1 , wherein the substrate comprises a bulk substrate wafer, the method further comprising:
forming a plurality of epitaxial semiconductor islands on the substrate;
epitaxially growing a plurality of epitaxial structures across the substrate, wherein the plurality of epitaxial structures correspond to different semiconductor devices;
forming a plurality of ohmic contacts to the plurality of epitaxial semiconductor islands; and
singulating the bulk substrate wafer to provide individual semiconductor devices.
27 . (canceled)
28 . A semiconductor device, comprising:
a substrate;
an epitaxial semiconductor island on the substrate comprising a first material characteristic; and
a semiconductor region comprising a second material characteristic different from the first material characteristic and grown from the substrate and from the epitaxial semiconductor island, wherein the epitaxial semiconductor island extends to, contacts, or forms a part of, an active region of the semiconductor device.
29 . The semiconductor device of claim 28 , further comprising:
an ohmic contact on the semiconductor region, wherein the ohmic contact is conductively coupled to the semiconductor region.
30 . The semiconductor device of claim 28 , wherein the semiconductor region extends above the substrate, and wherein the epitaxial structure has a curvature such that the epitaxial structure extends up a sidewall of the semiconductor region.
31 . The semiconductor device of claim 30 , wherein the semiconductor region comprises a first semiconductor region, the semiconductor device further comprising:
a second semiconductor region on the substrate adjacent the epitaxial structure, wherein the second semiconductor region extends above the substrate, and wherein the epitaxial structure has a curvature such that the epitaxial structure extends up a sidewall of the second semiconductor region.
32 . The semiconductor device of claim 28 , wherein the epitaxial semiconductor island is formed in a recess in an upper surface of the substrate and extends above the upper surface of the substrate.
33 - 35 . (canceled)
36 . The semiconductor device of claim 28 , wherein the substrate comprises a trench therein, wherein the epitaxial semiconductor island is at least partially formed in the trench.
37 - 40 . (canceled)
41 . The semiconductor device of claim 28 , wherein the epitaxial semiconductor island forms a part of an active region of the semiconductor device.
42 - 45 . (canceled)
46 . A semiconductor wafer comprising the semiconductor of claim 28 .
47 . A singulated semiconductor device comprising the semiconductor of claim 28 .
48 . A semiconductor wafer, comprising:
a plurality of epitaxial semiconductor islands on an upper surface of the semiconductor wafer and comprising a first material characteristic;
wherein the plurality of epitaxial semiconductor islands are laterally spaced from one another along the upper surface of the semiconductor wafer and are configured such that semiconductor devices are formed from epitaxial material with at least one second material characteristic different from the first material characteristic that is grown between the epitaxial semiconductor islands and on the semiconductor wafer and extend to, contact or form a part of active structures of the semiconductor devices.
49 . The semiconductor wafer of claim 48 , further comprising:
a plurality of recesses in the upper surface of the semiconductor wafer, wherein the plurality of epitaxial semiconductor islands are formed in respective ones of the plurality of recesses and extend above the upper surface of the semiconductor wafer.
50 - 51 . (canceled)