GaSb - Dry Etching

GaSb - Dry Etching

Material Name: GaSb
Recipe No.: 8512
Primary Chemical Element in Material: Ga
Sample Type: Substrate, bulk
Uses: Etching
Etchant Name: None
Etching Method: Dry etching
Etchant (Electrolyte) Composition:
Dry etching
Two techniques of dry etching were applied: - sputter etching (dc sputtering) in a Leybold Z-400 Sputtering System;
- reactive ion etching (RIE) in a commercial Secon Mark 4 reactor.
Sputter etching was performed in Ar+ plasma at pressure p = 8 x 10 exp(-3) mbar, frequency of plasma agitation f = 13.5 MHz and with positively biased substrate at the voltage UDC = 120 ÷ 500 V. RIE system with a diode configuration chamber, a 13.56 MHz power supply and 6 gas lines equipped with mass flow controllers were used. The process gas pressure was measured by a capacitance mano- meter. Dry etching of GaSb and related materials surface was carried out with CCl2F2 or CCl4 plasma as active gas and H2 or N2 as gas thinner. All gases (5N BOC) were used at flow rate of 6.6 ÷ 23.9 sccm and working pressure of 75 ÷ 162 µbar. A source of CCl4 was 99.8% liquid source (LAB-SCAN Analitical Sciences), while O2 and CF4 gases were applied for reactor cleaning.

Deposition of passivating coatings
Surface passivation was performed by dipping and electrochemical techniques.
The following sulphur sources were used:
- inorganic compounds: Na2S, 21%(NH4)2S,
- organic compound- (NH2)2CS (thiourea),
both in aqueous solution or in alcoholic solutions: C3H7OH or C2H4(OH)2.
Electrochemical sulphuration was performed at RT and with electric current density varied in the range from 1.6·10 exp(-2) to 35 mA/cm2.

Lithography
Two techniques were used to define pattern on surfaces of GaSb wafers and GaSb based hetero- structures:
. photolithography with the use of Carl Suss MJB 21 UV 400 alignment and exposure equipment for critical dimension (CD) above 1 µm and Carl Suss MJB UV 250/350/400 system for pattern with CD<1 µm;
. E-beam lithography with JEOL 6400 scanning microscope equipped with Raith pattern generator.
Spin coating and backing process of photo- and electron - resists were carried out using Brewer Model 100CB Hotplate/Spinner with computer control parameters: spin speed v = 0 ÷ 6000 rpm, spin time t = 0 ÷ 999 s and hot plate temperature T = = 50 ÷ 300 C.
Procedure (Condition): No data
Note: No data
Reference: E. PAPIS-POLAKOWSKA, SURFACE TREATMENTS OF GaSb AND RELATED MATERIALS FOR THE PROCESSING OF MID-INFRARED SEMICONDUCTOR DEVICES, Electron Technology - Internet Journal 37/38 (2005/2006), 4, p. 1-34.