Chemistry Reference
In-Depth Information
The etching rate depends not only on various process parameters, but also on
the loading of the materials in the reactor. The consumption of reactive radicals
increases with increasing loading and therefore the radical concentration and etching
rate decreases.
Important characteristic data for dry etching technology are [88]
•
Etching rate
•
Selectivity (etching rates for different materials)
•
Directionality (isotropic or anisotropic)
•
Sidewall angle
•
Etched surface quality
•
Material damage
•
Uniformity
•
Reproducibility
Besides these important parameters, the reactive gas phase must be free of dust
particles to avoid disturbances of the microstructures by deposited dust particles (see
also Section 8.4). In Table 8.5, etching gases are summarized for various materials.
TABLE 8.5
Etching Gases for Various Materials
Silicon
CF
4
/O
2
,CF
2
Cl
2
,CF
3
Cl, SF
6
/O
2
/Cl
2
,
Cl
2
/H
2
/C
2
F
2
/CCl
4
,C
2
ClF
5
/O
2
,SiF
4
/O
2
,NF
3
,
CCl
4
,C
2
ClF
5
/SF
6
,C
2
F
6
/CF
3
Cl, Br
2
,CF
3
Cl/Br
2
,HBr
SiO
2
CF
4
/H
2
,C
2
F
6
,C
3
F
8
,C
4
F
8
,C
4
F
6
,CHF
3
Si
3
N
4
CF
4
/O
2
/H
2
,C
2
F
6
,C
3
F
8
,CHF
3
,NF
3
,CHF
3
/O
2
,CH
3
F, SF
6
Organics, polymers
O
2
,CF
4
/O
2
,SF
6
/O
2
Silicides
CF
4
/O
2
,NF
3
,SF
6
/Cl
2
,CF
4
/Cl
2
Al
BCl
3
, BCl
3
/Cl
2
, CCl
4
/Cl
2
/BCl
3
,SiCl
4
/Cl
2
Cr
Cl
2
, CCl
4
/Cl
2
Cu
Cl
2
/Ar
Mo,Nb,Ta,Ti,W
CF
4
/O
2
,SF
6
/O
2
,NF
3
/H
2
Au
C
2
Cl
2
F
4
,Cl
2
, CClF
3
GaAs
BCl
3
/Ar, Cl
2
/O
2
/H
2
, CCl
2
F
2
/O
2
/Ar/He, CCl
4
,PCl
3
,HCl,Br
2
,COCl
2
,SiCl
4
InP
CH
4
/H
2
,C
2
H
6
/H
2
,Cl
2
/Ar, Cl
2
/O
2
,HBr,CF
3
Br, Br
2
,HI,CH
3
I, I
2
NiFeCo
Ar/Cl
2
,N
2
/Cl
2
,H
2
/Cl
2
Sources:
Shul, R.J. and Fleming, J.G., Bulk si micromachining for integrated microsystems and MEMS
processing, In Shul, R.J. and Pearton, S.J., eds.,
Handbook of Advanced Plasma Processing
Techniques
, Springer, Berlin, Germany, pp. 419-458, 2000; Grill, A.,
Cold Plasma in Mate-
rials Fabrication from Fundamentals to Applications
, IEEE, New York, 1994; Boening, H.V.,
FundamentalsofPlasmaChemistryandTechnology
, Technomic, Lancaster, PA, 1988; Richter,
H.H. et al., Plasma etching in microelectronics, in
Low Temperature Plasmas: Fundamentals,
Technologies and Techniques
, in Hippler R. et al., eds, pp. 655-674, Wiley-VCH, Weinheim,
Germany, 2008.
