Research departments

HF Vapor phase Etcher


HF Vapor Phase Etcher

Equipement Vapeur HF

Brand: Idonus
Equipment : HF VPE 100mm


Contact :


Laurent ROBERT
TEMIS Sciences Building – Office N1-21
03 81 66 66 47 (Office)
laurent.robert@femto-st.fr or tristan.faure@femto-st.fr


Location :


TEMIS cleanroom - Chemistry Area



Photo Paillasse Vapeur HF



Why ?



To release a fragile micro-device, which cannot be done in liquid phase, without using water rinsing or drying.

Principle :



A sacrificial layer of silica (Si02), positioned under the device to release, is chemically etched in dry phase by means of hydrofluoric acid vapor (HF). Generally, the SOI wafers are used in this technology.


Advantages: ease of implementation, one step, no bonding, no drying.
Two types of release can be usedby under-etching or by drilling.

Schéma Libération par Vapeur HF

Release by under-etching

Schéma perçage par Vapeur HF

Release by drilling



Chemical reactions involved :

Réaction chimique Vapeur HF

 

Water is both a reagent and a reaction product which may be responsible for bonding structures. For a totally dry etching, it is necessary to evaporate water as and when it is produced, so it explains why the sample must be heated.

Technical specifications :

- Heated wafer holder (35 to 60 °C)
- Electrostatic or mechanic clamping

Schéma sous-gravure max par Vapeur HF



- Maximal under-etching : 150 µm
- Under-etching rate : variable (typically 1 µm per minute for a silica layer of 2 µm)
- Used masks : Al, Au, Pt, photoresists


Use: safe because the operator did not enter contact with the HF liquid or vapor (devices placed in a bench with extraction). The wafer is first placed over the HF container (the wafer holder serving as a lid) and then the HF liquid is filled into the reaction chamberby the action of a valve.

Photo_Equipement Vapeur HF_1



Achieved results :

Application1_Vapeur HF

SOI membrane release : x-y « comb drive » table

Application2_Vapeur HF

Silica etching progress : 80 µm for 80 min (view through a 400nm thick Si layer)

Application3_Vapeur HF

Si walls release : etching of a 2µm thick silica layer during 1h30