Fabrication of suspended GaN microstructures using GaN‐on‐patterned‐silicon (GPS) technique

Abstract

We demonstrate a technique for fabricating suspended gallium nitride (GaN) microstructures without direct etching of GaN. The process combines a selective area growth of GaN‐on‐patterned‐silicon substrate (GPS) and a subsequent sacrificial wet etching of the silicon under the GaN structures. Both anisotropic and isotropic wet etching techniques are used to carry out the sacrificial etching. The pattern‐dependent lateral growth property of GaN growth is also discussed. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Group III nitride and SiC based MEMS and NEMS: materials properties, technology and applications

“…The latter method was also proposed to simplify the MEMS technology. GaN [70,172,173] and SiC [174][175][176] were grown on a Si substrate, where the patterns of the final structure (cantilever and bridge) were implemented as raised features. After the growth, the Si was directly etched via the side walls without the need to pattern the GaN layer (see section 3.3) [70,172,173].…”

“…Functional layers on patterned substrates. Yang and workers proposed the growth of GaN on patterned Si substrates in order to avoid the patterning of the functional layers [70,172,173]. Consequently, only equipment for Si micromachining is necessary for the patterning of the structure.…”

“…Finally the Si mould is wet chemically etched from the SiC microdevice, taking advantage of the extremely high-etch selectivity between Si and SiC. This technique was used to form fuel atomizers [386], microengine structures [387] and microturbo machines (c) undercutting by isotropic etching [172]. [388].…”

Electrical Isolation of Dislocations in Ge Layers on Si(001) Substrates through CMOS Compatible Suspended Structures

“…In utilizing cheap wet etchants, active layers are mainly made upon sacrificial layers, generally dielectrics, that can be selectively removed [6] due to their high etch selectivity in wet isotropic etchants [9]. Anisotropic etchants, such as potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH), have also been used to create suspended structures by a 'brute-force' etch against the etch-resistive {111} planes in Si(001) substrates [10,11]. An alternative method has been to use a post-CMOS fabrication technique to create suspended micro-hotplates [12,13], exploiting the underetching rates of a Si(001) substrate in TMAH [14][15][16].…”

Integrated photonics on silicon with wide bandgap GaN semiconductor

“…When considering substrate under-etching techniques, SiC and Si are excellent candidates since sapphire etching remains very challenging. 19,20 SiC offers a lower lattice mismatch with GaN (e.g., 3.5% for 6H-SiC (0001)) compared to Si (17% for Si (111)), but its cost is considerably larger. In addition, using Si is crucial for the forthcoming integration of photonics and electronics by taking advantage of both its low cost and well-established technology and the unique optoelectronic properties of III-nitrides.…”