Inattentive HF concentration vapors phase release of micro-electro-mechanical systems and optical systems
A low-cost, conventional release using low concentrations of HF to overcome the stiction of MEMS structure.
1 . A method to release micro-electro-mechanical structure (MEMS) from a sacrificial substrate comprising the steps of: providing an aqueous solution of hydrofluoric acid; locating said substrate a distance from said aqueous solution of hydrofluoric acid; exposing said substrate to vapors released from said aqueous solution of hydrofluoric acid until said MEMS structure is released from said substrate; and
said aqueous solution of hydrofluoric acid has a concentration of 1% or less.
2 . The method of claim 1 wherein said distance is around 5 cm.
3 . The method of claim 1 wherein said time is around 10 minutes.
4 . The method of claim 1 wherein said time is around 16 minutes.
5 . The method of claim 1 wherein said time is around 25 minutes.
6 . The method of claim 1 wherein said time is around 35 minutes.
7 . The method of claim 1 wherein said sacrificial substrate is SiO 2 or an insulating material that can be chemically etched by hydrofluoric acid.
8 . The method of claim 1 wherein said sacrificial substrate is a metal.
9 . The method of claim 1 wherein said sacrificial substrate is Titanium, Aluminum, Copper, or a metal that is chemically etched by hydrofluoric acid.
10 . The method of claim 1 wherein said sacrificial substrate is Titanium, Aluminum, Copper or a metal that is chemically etched by hydrofluoric acid.
11 . The method of claim 1 wherein said substrate is a wafer having a diameter of 8 inches or less.
12 . The method of claim 1 wherein said hydrofluoric acid concentration is maintained.
13 . The method of claim 1 wherein no catalyst is used.
14 . The method of claim 1 wherein water is used as a dilutant.
15 . The method of claim 1 wherein a chamber temperature below 30° C. allows Hf vapor etching.