Wafer Etching Process
The manufacture of semiconductor components such as integrated circuits and MEMs relies on the use of various wafer etching process methods to produce the required structures and connections. The most commonly used wet etching processes used in industry include KOH, BOE, Silicon Nitride, and Piranha etch. Etching processes can be done on silicon and gallium arsenide (GaAs) as well as with metals that include aluminum, copper, and gold. Modutek provides wet bench technology and equipment to support a wide variety of wet etching applications. Process engineers working at semiconductor manufacturing facilities and research centers use wet bench stations and other equipment from Modutek to meet the requirements of their wafer processing applications.
The etching silicon wafers with potassium hydroxide (KOH) creates microscopic structures in the silicon. The etching rate is controlled by the temperature of the etching bath, the concentration of KOH and the crystalline structure along with any impurities in the silicon wafer. KOH etching provides a low cost and repeatable etching process that etches quickly. Modutek supports KOH etching applications using either the TFa or TT series of PFA Teflon tanks.
Buffered Oxide Etch (BOE)
BOE is also known as buffered HF or BHF and is primarily used in etching thin films of silicon nitride or silicon dioxide. It consists of hydrofluoric acid and a buffering agent such as ammonium fluoride. BOE provides a consistent repeatable process, does not undercut masked oxide, does not contaminate or stain diffused silicon surfaces, and is compatible with photoresist. Modutek supports the BOE process specifically with the F SERIES sub-ambient filtered etch bath.
Silicon Nitride Etching
Silicon nitride is used as a masking material in semiconductor manufacturing. It is deposited on the silicon wafer as a thin film and is etched with hot phosphoric acid. Hot phosphoric acid strip is performed at 180 degrees C in a nitride etch bath. Nitride etch baths provide precise temperature control by regulating the de-ionized water to phosphoric acid ratio. Modutek’s silicon nitride etch baths provide accurate process control with consistent repeatability and a high level of safety.
The piranha solution is made up of a mixture of hydrogen peroxide and sulfuric acid and is used to clean silicon wafers during various stages of the semiconductor manufacturing process. It typically consists of 3 parts concentrated sulfuric acid to one part of 30 percent hydrogen peroxide. The solution cleans organic compounds from silicon substrates and will oxidize most metals. It is frequently used to clean photoresist from the surface of silicon wafers. Modutek can evaluate the silicon wafer cleaning requirements that a customer requires and provide suitable recommendations from its full line of wet processing equipment.
Copper, Gold and Aluminum Etching
Microelectronic devices developed on silicon wafers must use metallic connections to conduct electric signals. Metals that are used for this purpose include aluminum, copper or gold which are deposited on the silicon wafer. During the silicon wafer fabrication process some of the metals will need to be etched. Etching metals can be challenging and effective etching relies on selecting the appropriate chemicals and process. In these cases the use of Modutek’s Vacuum Metal Etcher provides a precise process for etching metal layers. Wafers are etched within a vacuum so that hydrogen bubbles, an etching reaction which causes “snow” and “bridging”, are immediately removed from the surface of the wafer. The hydrogen bubbles are then immediately exhausted by an evacuating pump in the Vacuum Metal Etcher. Modutek’s equipment can be use a variety of etchant solutions to etch different metals.
Modutek Support for Wafer Etching Process Applications
Modutek has been a premier supplier of semiconductor manufacturing equipment for over 35 years, and has a full line of wet processing equipment to support a wide variety of wafer etching process applications. Modutek’s equipment delivers reliable and repeatable results safely and accurately. For a free quote or consultation on selecting the right equipment for your wafer etching process, contact Modutek today.