| abstract |
Solutions of choline base, (2-hydroxyethyl)trimethylammonium hydroxide, in water and/or lower alkanols may be stabilized by the addition of a stabilizing concentration of a formaldehyde source. The stabilized solutions may be used as cleaning solutions, etchants for semiconductors and metal layers, and developers and strippers for positive working photoresists, and for other uses where a metal ion-free base is desired. |