The polycrystalline ingot is obtained by a Horizontal Gradient Freeze (HGF) which is the cooling of an InP Melt obtained by reaction between liquid indium and phosphorus vapour at 30 atmospheres. This method produces high purity, stoechiometric Indium Phosphide. The ingot is 300 mm long and the section is half of a 45 mm diameter. Each ingot weighs 1 250 g.

Two techniques: vapor pressure controlled Czochralski (pCZ) and vertical Bridgman.
pCZ in a pulling technique, the crystal being pulled up from the inP melt in the crucible within a tight inner chamber having an independently heated reservoir of condensed phase phosphorus to maintain a controlled phosphorus pressure and with optimized graphite heaters around the chamber.
Bridgman is a boat growth method by solifying the InP melt from a seed crystal placed at a bottom seeded crucible with a set of graphite resistance heaters regulated separately to guarantee the solidification sliding the thermal profile along the crucible.
In both cases the growth assembly and the heater system are enclosed in a water-cooled high pressure stainless steel vessel, boron oxide acts as an encapsulant suppressing phosphorus evaporation, the power is controllably ramped down until the entire charge is solidified with the surrounding insulation designed to produce a smooth thermal profile.
The InP single crystal is doped at this stage by introducing impurities in the bath such as iron, sulphur, tin or zinc.

The orientation is indicated on the wafers by two flats (long flat for orientation, small flat for identification). Usually the E.J. standard (European-Japanese) is used. The alternate flat configuration (U.S.) is mostly used for Ø 4" wafers.

Either exact (100) or misoriented wafers are offered.

In response to the needs of the optoelectronic industry, InPACT offers wafers with excellent accuracy of the OF orientation : < 0.02 degrees. This feature is an important benefit to customers making edge-emitting lasers and also to manufacturers who cleave to separate dies.

There are two common specs : chemical edge processing or mechanical edge processing (with an edge grinder).

Wafers are polished by means of a chemical-mechanical process resulting in a flat, damage-free surface. InPACT provides both double-side polished and single-side polished (with lapped and etched back side) wafers.

Wafers go through many chemical steps to remove the oxide produced during polishing and to create a clean surface with stable and uniform oxide layer that is ready for epitaxial growth - epiready surface and that reduces trace elements to extremely low levels (EPICLEAN ). After final inspection, the wafers are packaged in a way that maintains the surface cleanliness. InPACT guarantees the quality of the epiready for 6 months.
Specific instructions for oxide removal are available for all types of epitaxial technologies (MOCVD, MBE).

As part of our Statistical Process Control/Total Quality Management Program, extensive database recording the electrical and mechanical properties for every ingot as well as crystal quality and surface analysis of wafers are available. At each stage of fabrication, the product is inspected before passing to the next stage to maintain a high level of quality consistency from wafer to wafer and from boule to boule.