Specific Process Knowledge/Etch/Wet III-V Etches: Difference between revisions

This is a collection of III-V wet-etches; not all etches are currently used at DTU Danchip why the rates should be tested before use. Make sure you have the proper education in mixing of chemicals before use.

HCl(37%):H₃PO₄(85%) is a selective, anisotropic and slow etching of InP. Very slow rate in quarternaries. The etch rates depend on the orientation of the features and have not yet been calibrated at DTU Danchip.

See rates below for InP, PQ(1.n) and InGaAs lattice-matched to InP. '''The acronym PQ(1.n) denotes a lattice-matched InGaAsP with a band gap corresponding to a wavelength of 1.n mm.'''  

{| border="1" style="text-align: center; width: 400px; height: 100px;"

! colspan="4" style="text-align: center;" style="background: #efefef;" | HCl(37%):H₃PO₄(85%) etch rates, nm/min

H₂SO₄(10%):H₂O₂(35%):H₂O is a selective etch of InGaAsP with very low etch rate in InP. '''The acronym PQ(1.n) denotes a lattice-matched InGaAsP with a band gap corresponding to a wavelength of 1.n mm.'''  

{| border="1" style="text-align: center; width: 500px; height: 100px;"

! colspan="6" style="text-align: center;" style="background: #efefef;" | H₂SO₄(10%):H₂O₂(35%):H₂O etch rates, nm/min

! scope="row" width="20%" |Etchant

! width="20%" |InP

! width="20%" |PQ(1.1)

! width="20%" |PQ(1.3)

! width="20%" |PQ(1.5)

! width="20%" |InGaAs

|1:1

Concentrated H₂SO₄(96%) is a selective etch of InP with a very low etch rate in InGaAsP.

! colspan="6" style="text-align: center;" style="background: #efefef;" | H₃PO₄(90%) etch rates, nm/min

|H₂SO₄(96%)  

H₃PO₄(85%):H₂O₂(35%):H₂O is a GaAs/AlGaAs-etch which gives a better surface quality than H₂SO₄-based etches.

! colspan="4" style="text-align: center;" style="background: #efefef;" | H₃PO₄(85%):H₂O₂(35%):H₂O etch rates, nm/min

|'''2,3'''

'''(1)''' Temperature of mixture is ~22 C (no heating during etch). Data is obtained using magnetic stirring with sample on flat basket. '''(2)''' Refrigerated H2O used during mixture of etch, and mixture kept at 17 C during etch. '''(3)''' 10:2:30 gives smoother etch than 10:2:60.

==BHF etch==

BHF etches SiO₂ and removes native oxide on InGaAs. '''Do not use BHF unless you know the dangers involved with this chemical and always use 4H gloves!'''.

! colspan="4" style="text-align: center;" style="background: #efefef;" | BHF etch rates, nm/min

! scope="row" width="30%" |Etchant

! width="20%" |SiO₂ '''¹'''

! width="20%" |E-beam Ti '''²'''

|BHF 1:7

|202

|52

 

'''(1)''' Process '''SiO2thi1''' in PECVD2. '''(2)''' Ti from Titest.prg on Physimeca. It seems there is no measurable etchig during first 10 seconds.

 

Solid C₆H₈O₇ is mixed 1:1 by weight with H₂O using magnetic stirring. The solution C₆H₈O₇:H₂O is thereafter mixed 4:1 volume ratio with H₂O₂.

The above C₆H₈O₇:H₂O₂ solution has an etch-rate of ~360 nm/min in GaAs and < 0.5 nm/min in AlAs @ 25 C.