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Center of MicroNanoTechnology CMi

Idonus HF VPE-100

Idonus HF VPE-100

Attention Remarques préliminaires fondamentales:
  • SAFETY OPERATOR MANUAL (HERE) / PROCÉDURE DE SÉCURITÉ POUR OPÉRER SUR LES WETBENCH DU CMI A LIRE OBLIGATOIREMENT (ICI)

Table des matières: CMI

  1. Introduction
  2. Description
  3. Operating instructions

I. Introduction CMI

This installation is dedicated to realise HF vapour release of structures.

The hydrofluoric acid vapor phase etcher (HF VPE) consists of a reaction chamber and a waferholder. HF evaporates at room temperature and the etching process starts spontaneously. The etch rate is controlled by the wafer temperature that can be adjusted from 35C to 60 C.

The text below describes the equipment and the procedure to follow carefully.

II. Description CMI

The container is a system composed of a reaction chamber and a reservoir. The reservoir has the function to store HF acid when the HF VPE apparatus is not in operation and allows a simple and safe transfer of the acid in and out of the reaction chamber. The working principle of the reservoir and the container is called communicating vessels. When the reservoir is in high position, (i.e. the reservoir handle is pulled up) the liquid can flow into the reaction chamber (if the valve is open). If the reservoir is in low position, (i.e. reservoir handle is down) the liquid flows from the reaction chamber into the reservoir. The valve is open if the tap is vertical and closed if the tap is horizontal. The tap can be turned in both directions and does not have a stopper. Always cover the HF VPE apparatus with the lid if it is not in operation. The connecting cable is water proof if it is connected to the socket. The standard mechanical clamp ring is able to clamp 100 mm wafers as well as 4 wafers. The wafers are held by 6 clips. Three nuts fix the wafer mechanically to provide a good thermal contact to the heating plate. The electrostatic clamping is realized by an optional bipolar electrostatic chuck. The high voltage to drive the electrostatic chuck is created inside the wafer holder. Flat, conductive substrates can be clamped by the electrostatic chuck. Due to its design a wafer as well as multiple chips can be clamped. The chips have to be placed in order to cross two electrodes.

Idonus HF VPE-100

The front panel of the controller box is spray water resistant. The controller box should not come in contact with any liquid!

III. Operating instructions CMI

Mechanical clampingElectrostatic clamping
  • Place the mechanical clamping ring in front of you so that the bolts are facing upward.
  • Place your wafer on the ring so that the surface to be etched faces down.
  • Place the wafer holder over the clamping ring and fit the bolts into the holes of the wafer holder.
  • Use the three nuts to fix the clamping ring. Do not overturn the plastic screws. Overturning the screws may result in damage of the screws, the clamping ring or the wafer!
Electrostatic clamping can be used additionally to the clamping ring or alone. If wafers are clamped by electrostatic force only a minimal force is required. If a too high force is applied the removal of the wafer can become critical due to residual fixed charges present in the dielectric isolation of the electrostatic chuck. These fixed charges disappear slowly without any further action.
  • Place the wafer holder in front of you so that the electrostatic chuck is facing upward.
  • Place your wafer or chip on the electrostatic chuck so that the surface to be etched is facing you.
  • Switch the power for the electrostatic chuck to ON position.
  • Adjust the force by turning the potentiometer.
  • Make sure your wafer is fixed.
Mechanical clampingElectrostatic clamping
  • Loosen the three nuts.
  • Lift carefully the wafer holder from the clamping ring. The wafer may stick to the holder and release whole you are handling the holder. Usually, the wafer releases within several seconds from the wafer holder.
  • Take the wafer off the clamping ring. Do not touch the wafer! If the SiO2 is etched at too low temperatures HF may condense on the wafer surface. If any other material is present on the wafer, HF may diffuse in the material or react with it forming another dangerous chemical.
  • Place the wafer holder so that the wafer is facing you.
  • Switch OFF the electrostatic clamp.
  • Take the wafer off the heating plate. Do not touch the wafer holder; it may be contaminated with HF. Use soft tweezers which do not scratch the dielectric layer isolating the electrodes of the electrostatic chuck! Rinse the tweezers after usage.