Silicon nitride

About: Silicon nitride is a research topic. Over the lifetime, 32678 publications have been published within this topic receiving 413599 citations. The topic is also known as: N₄Si₃.

Silicon nitride ceramic and cutting tool made thereof

Abstract: Provided is a silicon nitride based ceramic which is particularly useful for use as a cutting tool (10) in the high speed chip forming machining of metallic materials. The ceramic is preferably composed of at least 85 volume percent (v/o) beta silicon nitride phase and less than about 5 v/o intergranular phase. The ceramic has greater than 0.2 weight percent (w/o) magnesia, greater than 0.2 w/o yttria, where the sum of magnesia and yttria is less than 5 w/o. The ceramic has less than 0.2 v/o porosity. The tool (10) has a rake face (30) joined to flank faces (50) by cutting edges (70).

Oxidation resistance of titanium–aluminium–silicon nitride coatings

Abstract: The demands for cutting tools tend to still longer service life and higher speed in cutting processes. To fulfil these demands, hard and wear resistant thin coatings have to be deposited on cutting tools. The functionality of the coating must be ensured at the high temperatures reached at the cutting edge during machining. At these temperatures, oxidation of the coatings may lead to problems. Titanium–aluminium nitride coatings show an oxidation behaviour superior to the widely used titanium nitride coatings. To further enhance the oxidation resistance, the addition of silicon to titanium–aluminium nitride films is analysed in this work. The investigated coatings were deposited by reactive DC magnetron sputtering on high-speed steel. The composition of the coatings could be varied by the type of target used and the applied voltage to each target and was determined by glow discharge optical spectroscopy (GDOS). The coating thickness is derived from ball cratering and ranges between 3 and 6 μm. The adhesion of the coatings is analysed by the scratch test. The coated samples are subjected to an oxidation test, where they are exposed to a temperature of 800 or 1000 °C and an oxygen partial pressure ranging between 1 and 100 mPa for 1 h. The results of the TiAlSiN coatings are compared with TiAlN coatings to evaluate the influence of the silicon. Ultra-microhardness measurements are performed prior and after the oxidation tests. Changes in the composition due to diffusion processes are measured with GDOS over the whole coating thickness and the coating/substrate interface. X-ray photoelectron spectroscopy reveals changes of composition and binding energy in the near surface zone.

Ultrahigh-selectivity silicon nitride etch process using an inductively coupled plasma source

Abstract: A very high-selectivity silicon nitride etch process has been developed on an inductively coupled plasma etching system which uses a NF3/O2/NH3 (nonchlorine) chemistry. Etch selectivity of low-pressure chemical vapor deposition nitride to thermal oxide greater than 100:1 was achieved at a nitride etch rate of 500 A/min. A NF3/O2 chemistry was optimized for nitride to oxide selectivity of about 12:1, with a nitride etch rate of 1200 A/min. The addition of NH3 inhibits oxide etching thus enhancing selectivity. The net etch rate for oxide may be reduced to zero while maintaining a reasonably high etch rate for nitride thus resulting in essentially infinite selectivity. The process is stable, repeatable and creates no particles. A split lot test on device wafers against standard wet etch process demonstrates superior process and device performance.

Some Properties of Vapor Deposited Silicon Nitride Films Using the SiH4 ‐ NH 3 ‐ H 2 System

Abstract: The effects of process variables on the growth rate and properties of insulating films grown from a hydrogen‐silane‐ammonia mixture have been studied. Growth rate vs. 1/T is observed to have a break at 900°C, coincident with an observed amorphous‐polycrystalline transition. Hardness, growth rate, and refractive index are found to move toward values appropriate for silicon as the per cent ammonia is reduced. The thermal expansion coefficient can be varied from approximately that of silicon to appreciably more by increasing the per cent ammonia. A variety of other properties, such as breaking strength and Youngs' modulus were also measured and are discussed.