Electroplating

Technical staff 

David BOURRIER (IE-Area responsible)
Sylviane BASTER (AI)

The electroplating area has 2 components: Anisotropic wet etching, and electrolytic metal growth.
 

Anisotropic wet etching

The anisotropic chemical etching is to etch Silicon chemically on depths of a few microns to several hundred microns with an alkaline chemical solution. The redox reaction that occurs between silicon and the solution lead the dissolution of the preferential directions. The realization of a prior nitride or Silicon oxide mask can locate this etching and achieve grounds (membrane, cavities, and trenches).
 

Electroplating 

This technique is to turn the metal ions in a solution in metal deposits. The deposit can be full substrate or localized in thicknesses ranging from a few µm to several hundred µm.  The silicon substrate is immersed in a solution containing metal ions to be deposited. A current is imposed between the substrate is counter electrode. This current will allow the transformation of the ions in metal atoms. The composition of the bath, the density of the current, and the agitation influences the characteristics of the deposit.

 

Means of fabrication

Paillasses de gravure anisotrope

 

Paillasses pour la mise au point des bains électrolytiques

 

 

Equipement RENA fontaine pour le dépôt d'or sur substrats 4 pouces

 

 

Equipement RENA fontaine pour le dépôt de cuivre

 

 

Equipement RENA rack pour le dépôt de cobalt, fer, nickel

 

 

Equipement RENA fontaine pour le dépôt d'or sur substrats 6 
pouces

 

Titration

 

Stripping de résine (premier plan) 
Traitement de surface 
(deuxième plan)

 

 

CVS

 

 

AAS

 

 

Poste anodisation

 

Know how

Anisotropic wet etching

  • KOH: the rate for  the <100> plans rangs from 0.5 to 2.5 µm/min for concentrations of 20 to 50% by weight and temperatures of 50 to 90 °. This solution of attack requires a mask in Silicon nitride: 

La vitesse de gravure des plans 100 variant de 0.5 à 2.5 µm /min pour des concentrations de 20 à 50 % en poids et des températures de 50 à 90°. Cette solution d'attaque nécessite un masque en nitrure de silicium 
 

  • TMAH : the rate for the <100> plans rangs from 0.2 to 1 µm/min for concentrations of 20 to 50% by weight and temperatures of 50 to 90 °. This solution does not etch oxide and therefore allows membranes.


KOH etching

IPA influence on TMAH etching

TMAH 20% - 2 min

 

TMAH 20% + 17 % IPA - 2 min

 

 

Electroplating 

Gold :Continuous current full plate or in a resist mould  for thicknesses up to 10 µm. Can be deposited on 4 or 6 inches substrates. This deposit is with low mechanical stress< 10 MPa and homogeneous (inhomogeneity &LT; 5%)

  MEMS 

-    RF

 

  • Copper : Continuous or pulsed current,  full plate or in a resist mould for depths up to 100 µm 

 

 

Energy convertor

 

 

  • Co-Ni-Fe: Continuous current,  full plate or in a resist mould for depths up to a few tenth of µm

Micro converter for power device

 

  • Platinum : Continuous current,  in a resist or alumina mould for depths up to a few µm

 

Nanowires  

 

  • SAC : Continuous current,  in a resist mould for depths up to 100 of µm 

 SAC bumps before et after reflow 

 

  • Gold : By immersion for the protection of deposited copper.