Process of forming an electronic device including an access region

1. A process of forming an electronic device comprising:

forming a channel layer overlying a substrate;

forming a barrier layer overlying the channel layer;

forming a p-type semiconductor layer over the barrier layer;

patterning the p-type semiconductor layer to define at least part of a gate electrode of a transistor structure;

forming an access region layer over the barrier layer after patterning the p-type semiconductor layer, wherein the access region layer includes Al f In g Ga (1-f-g) N, wherein 0<f≤1 and 0≤g≤0.3;

forming a drain electrode such that, within the transistor structure, a bottommost surface of the drain electrode is spaced apart from the barrier layer by at least the access region layer; and

forming a source electrode such that, within the transistor structure, a bottommost surface of the source electrode is spaced apart from the barrier layer by at least the access region layer.

2. The process of claim 1 , wherein forming the access region layer comprises selectively growing the access region layer to form a first access region and a second access region, wherein:

forming the drain electrode is performed such that the drain electrode contacts the first access region, and

forming the source electrode is performed such that the source electrode contacts the second access region.

3. The process of claim 1 , wherein forming the access region layer comprises depositing the access region layer over gate electrode.

4. The process of claim 3 , further comprising removing a portion of the access region layer overlying the gate electrode.

5. The process of claim 1 , wherein forming the barrier layer comprises forming the barrier layer including Al b In c Ga (1-b-c) N, wherein 0<b≤0.1 and 0≤c≤0.1.

6. The process of claim 1 , further comprising forming a semiconductor layer over the gate electrode, wherein the channel and semiconductor layers have a same semiconductor base material.

7. The process of claim 1 , further comprising removing an exposed portion of the barrier layer that is adjacent to the gate electrode.

8. The process of claim 7 , further comprising recessing a portion of the channel layer adjacent to the gate electrode.

9. The process of claim 1 , further comprising:

forming an insulating layer over the access region layer;

patterning the insulating and access region layers to define a contact opening over the gate electrode; and

forming a gate interconnect within the contact opening.

10. The process of claim 1 , wherein:

forming the drain electrode is performed such that the drain electrode contacts the access region layer,

forming the source electrode is performed such that the drain electrode contacts the access region layer, and

the process further comprises forming a gate interconnect coupled to the gate electrode.

11. The process of claim 10 , wherein:

forming the channel layer comprises depositing the channel layer including a GaN layer,

forming the barrier layer comprises depositing the barrier layer including Al b In c Ga (1-b-c) N, wherein 0<b≤1 and 0≤c≤0.3,

forming the p-type semiconductor layer comprises depositing a p-type GaN layer,

forming the access region layer is performed such that the access region layer has a same or higher Al content as compared to the barrier layer,

the process further comprises:

forming an insulating layer over the access region layer; and

patterning the insulating and access region layers to define a contact opening over the gate electrode;

forming the gate interconnect comprises forming the gate interconnect within the contact opening, and

the electronic device includes a high electron mobility transistor.

12. A process of forming an electronic device comprising:

forming a channel layer overlying a substrate;

forming a spacer layer overlying a substrate;

forming a barrier layer overlying the channel layer;

forming a p-type semiconductor layer over the barrier layer;

patterning the p-type semiconductor layer to define at least part of a gate electrode of a transistor structure;

forming an access region layer over the barrier layer after patterning the p-type semiconductor layer, wherein the access region layer includes Al f In g Ga (1-f-g) N, wherein 0<f≤1 and 0≤g≤0.3;

forming a drain electrode spaced apart from the barrier layer by at least the access region layer; and

forming a source electrode spaced apart from the barrier layer by at least the access region layer,

wherein the spacer layer is disposed between the channel layer and the barrier layer or between the barrier layer and the gate electrode.

13. A process of forming an electronic device comprising:

forming a channel layer overlying a substrate;

forming a barrier layer overlying the channel layer;

forming an etch-stop layer over the barrier layer;

forming a sacrificial layer over the etch-stop layer;

patterning the etch-stop and sacrificial layers to define a gate region;

forming an access region layer over the barrier layer after patterning the etch-stop and sacrificial layers;

removing remaining portions of the etch-stop and sacrificial layers within the gate region after forming the access region layer; and

forming a p-type semiconductor layer within the gate region.

14. The process of claim 13 , wherein forming the access region layer comprises selectively growing the access region layer after patterning the etch-stop and sacrificial layers.

15. The process of claim 13 , wherein:

forming the access region layer comprises blanket depositing the access region layer, and

the process further comprises removing a portion of the access region layer that is within the gate region before removing remaining portions of the etch-stop and sacrificial layers.

16. The process of claim 13 , wherein forming the p-type semiconductor layer comprises depositing the p-type semiconductor layer within the gate region.

17. The process of claim 16 , wherein:

depositing the p-type semiconductor layer is performed as a blanket deposition, and

the process further comprises removing a portion of the p-type semiconductor layer outside the gate region.

18. The process of claim 13 , wherein:

forming the channel layer comprises depositing the channel layer including a first GaN layer,

forming the barrier layer comprises depositing the barrier layer including Al b In c Ga (1-b-c) N, wherein 0<b≤1 and 0≤c≤0.3,

forming the sacrificial layer comprises depositing a second GaN layer,

forming the etch-stop layer depositing the etch-stop layer including Al d In e Ga (1-d-e) N, wherein 0<d≤1 and 0≤e≤0.3, and the etch-stop layer has a higher Al content than the barrier layer,

forming the access region layer comprises blanket depositing the access region layer including Al f In g Ga (1-f-g) N, wherein 0<f≤1 and 0≤g≤0.3, wherein the access region layer has an Al content between the Al contents of the barrier and etch-stop layers,

the process further comprises removing a portion of the access region layer lying within the gate region,

forming the p-type semiconductor layer comprises blanket depositing a p-type GaN layer after removing the remaining portions of the etch-stop and sacrificial layers,

the process further comprises removing a portion of the p-type semiconductor layer outside the gate region, and

the electronic device includes a high electron mobility transistor.

19. The process of claim 13 , wherein the access region layer includes Al f In g Ga (1-f-g) N, wherein 0<f≤1 and 0≤g≤0.3.

20. The process of claim 13 , further comprising:

forming a drain electrode that contacts a first portion of the access region layer;

forming a source electrode that contacts a second portion of the access region layer, wherein the gate region is disposed between the first and second portions of the access region layer; and

forming a gate interconnect coupled to the gate electrode.