Method of manufacturing micro devices
A method of manufacturing micro devices includes: preparing a III-nitride epitaxial structure including a p-type III-nitride layer, an n-type III-nitride layer on the p-type III-nitride layer, a Al x III_others 1-x N layer on the n-type III-nitride layer, and an undoped III-nitride layer on the Al x III_others 1-x N layer; forming a photoresist layer on the III-nitride epitaxial structure to contact the undoped III-nitride layer; patterning the photoresist layer; performing a first plasma etching process to the III-nitride epitaxial structure through the patterned photoresist layer to form a trench in the etched III-nitride epitaxial structure, in which the trench extends from the etched photoresist layer at least to the Al x III_others 1-x N layer; and performing a second plasma etching process to the etched III-nitride epitaxial structure until the etched III-nitride epitaxial structure is cut into a plurality of micro devices and a top surface of the etched Al x III_others 1-x N layer is exposed.
1 . A method of manufacturing micro devices, comprising:
preparing a III-nitride epitaxial structure comprising a p-type III-nitride layer, an n-type III-nitride layer on the p-type III-nitride layer, a Al x III_others 1-x N layer on the n-type III-nitride layer, and an undoped III-nitride layer on the Al x III_others 1-x N layer, wherein x is greater than 0.05;
forming a photoresist layer on the III-nitride epitaxial structure with the undoped III-nitride layer contacting the photoresist layer;
patterning the photoresist layer;
performing a first plasma etching process to the III-nitride epitaxial structure through the patterned photoresist layer to form a trench in the etched III-nitride epitaxial structure, wherein the trench extends from the etched photoresist layer at least to the Al x III_others 1-x N layer; and
performing a second plasma etching process to the etched III-nitride epitaxial structure until the etched III-nitride epitaxial structure is cut into a plurality of micro devices and a top surface of the etched Al x III_others 1-x N layer is exposed, wherein a lateral length of the micro devices is smaller than about 100 μm.
2 . The method of claim 1 , wherein the performing the first plasma etching process extends the trench from the etched photoresist layer to the n-type III-nitride layer.
3 . The method of claim 1 , further comprising stripping the etched photoresist layer after the performing the first plasma etching process and before the performing the second plasma etching process.
4 . The method of claim 1 , wherein the Al x III_others 1-x N layer is an n-doped layer.
5 . The method of claim 1 , wherein the Al x III_others 1-x N layer comprises an n-doped area in contact with the n-type III-nitride layer.
6 . The method of claim 1 , wherein the undoped III-nitride layer and the Al x III_others 1-x N layer have a first etch selectivity relative to the first plasma etching process, the n-type III-nitride layer and the Al x III_others 1-x N layer have a second etch selectivity relative to the second plasma etching process, and the first etch selectivity is smaller than the second etch selectivity.
7 . The method of claim 1 , further comprising:
placing the III-nitride epitaxial structure on a metal layer with the p-type III-nitride layer contacting the metal layer before the forming the photoresist layer, wherein the performing the second plasma etching process exposes portions of the metal layer.
8 . The method of claim 7 , further comprising:
etching the metal layer into a plurality of metal pads respectively under the micro devices.