Process for the plasma etching of materials not containing silicon
View Patent ↗A process enables plasma etching of materials that do not contain silicon. The process is particularly suitable for the side wall passivation of chromium layers in masks for fabricating semiconductor components. The plasma contains oxygen and/or nitrogen, and at least one silicon-donating compound is introduced into the plasma. This allows efficient passivation of side walls.
1. A plasma-etching process for the fabrication of a mask used in the fabrication of a semiconductor component, which comprises:
providing a quartz substrate with a chromium layer;
generating an etching plasma containing at least one of oxygen and nitrogen;
introducing at least one silicon-donating compound into the plasma, the silicon-donating compound being a gaseous molecule selected from the group consisting of SiH 4 , SiF 4 , SiH 2 Cl 2 , SiCl 2 O;
etching a trench structure in the chromium layer with the etching plasma; and
during the etching step, and after the at least one silicon-donating compound has been added to the plasma, coating the side walls of the trench structure with an SiO 2 a layer, an SiO 2 -like layer, or a silicon nitride layer for the formation of passivation layers.
2. The process according to claim 1 , wherein the at least one silicon-donating compound is a gaseous molecule of the formula SiA x H y , where
x=0, . . . , 4;
y=0, . . . , 4; and
x+y=4 and
A=Cl or A=F.
3. The process according to claim 2 , which comprises substituting a pair of two hydrogen atoms with one oxygen atom in the at least one silicon-donating compound of the empirical formula SiA x H y , while maintaining the silicon-donating compound in gas form under operating conditions.
4. The process according to claim 4 , wherein at least one silicon-donating compound has the formula SiCl 2 O.
5. The process according to claim 1 , which comprises reacting the plasma with at least one silicon-donating compound to form compounds selected from the group consisting of uncharged SiO 2 compounds, uncharged SiO 2 -like compounds, and silicon nitride compounds.
6. The process according to claim 5 , which comprises removing layers of one of the group consisting of silicon nitride layers, SiO 2 -like layers, and SiO 2 layers, which have been deposited during the etching on a base of the trench structure in the chromium layer on the guartz substrate, by charged particles of the etching plasma.
7. The process according to claim 6 , which comprises removing layers selected from the group consisting of silicon nitride layers, SiO 2 -like layers, and SiO 2 layers during one of cleaning and resist stripping of the chromium layer on the quartz substrate.