RASIRC BRUTE® Hydrazine
Ultra-Dry Hydrazine Gas for Low Temperature, Low Resistivity
Next generation semiconductor materials and architectures require new precursors and nitride sources for atomic layer deposition (ALD) processes. Low thermal budgets and high aspect ratio (HAR) structures create challenges for nitride deposition. Hydrazine gas is a strong nitridation designed specifically for low temperature ALD.
Ammonia and NH3 plasma do not yield high quality films at temperatures below 400°C. BRUTE Hydrazine enables low temperature ALD (sub-350°C) and low resistivity. Commonly available liquid hydrazine has safety issues and water contamination that leads to defects. In contrast, BRUTE Hydrazine gas is virtually water free. Highly reactive, BRUTE Hydrazine creates uniform nitride deposition for advanced materials.
Emerging Requirements for BRUTE Hydrazine
Nitride materials are used in many memory and logic device elements including contact barriers, sidewall spacers, contact etch stop layers, capacitor electrodes in DRAM, gate electrodes in CMOS, passivation layers, liners and caps. These various elements must all have low resistivity in order to minimize parasitic losses encountered as device size shrinks.
For gate stack optimization, researchers are investigating new high mobility channel materials such as SiGe, Ge, and InGaAs to meet market demands for faster, smaller, more power-efficient electronic devices. TiN electrodes and SiN side walls require low thermal budgets and low resistivity for very thin, defect free films.
Low thermal budgets help minimize problems including atomic diffusion, undesirable phase transitions, strain relaxation and defect formation. Current budgets for metal nitrides are limited to sub-400°C and rapidly moving to sub-300°C.
Innovative Hydrazine Vaporizer Design
BRUTE® Hydrazine provides a stable, reliable flow of anhydrous hydrazine gas from a liquid source in a sealed vaporizer. The liquid source combines hydrazine and a proprietary solvent for stability. Hydrazine diffuses across a proprietary membrane assembly, leaving the solvent behind. The resulting hydrazine gas is swept to process via the pressure gradient or by an optional carrier gas that flows through the membrane.
Hydrazine Gas Provides More Effective Reactivity vs NH3
Reaction thermodynamics for hydrazine are far more favorable for low temperature deposition compared to ammonia. Thermal ALD with ammonia gas (NH3) requires temperatures of 400°-600°C in order to achieve high quality, low resistivity films. In contrast, hydrazine gas has the highly reactive N-N bond for reaction with surface active sites.
Traditional plasma approaches can damage the substrate surface. Plasma requires a line of site, leading to uniformity problems in HAR structures used in memory applications. Nitrogen created by plasma methods cannot uniformly coat the internal side walls. Poor uniformity leads to high resistivity and unsatisfactory electrical characteristics in subsequent layers.
Low temperature, low pressure plasma methods have many problems. Long plasma exposure times and low growth per cycle limit throughput. These methods also have a tendency to incorporate oxygen into the film which is detrimental to obtaining low resistivity. Low temperature NH3 plasma methods lead to imcomplete dissociation, leaving residual hydrogen N-H bonds. This leads to very low growth per cycle and poor electrical properties. In some cases, these problems can be minimized by raising plasma power, however this approach can cause physical damage to HAR structures as well as other very thin films.
Researchers at University of California San Diego (UCSD) have recently reported low temperature growth of SiNx at 285C with hydrazine gas. In studies with hydrazine and (tert-butylimido)tris(diethylamido)tantalum (TBTDET), University of Colorado researchers found higher growth rates, higher density films, and improved resistivity for films grown with hydrazine versus ammonia under similar low temperature conditions 150°-250°C. University of Texas(Dallas) researchers have reported similar effective results for hydrazine in low temperature deposition of tungsten nitride at 200°-300°C.
Hydrazine Gas Superior to Standard Hydrazine
Hydrazine has been available commercially for many years, however it has not been available in a practical form needed for semiconductor manufacturing. Standard hydrazine has been problematic in several hydrazine thermal ALD studies due to the high concentration of oxygen found in the resulting Metal-Nitride films. Values ranging from 4-15% were reported SiNx and TiNx. This has been attributed to the low purity of commercially available 'Anhydrous' Hydrazine, which has water concentration ranging from 0.2-2.0%.
BRUTE Hydrazine delivers high purity anhydrous hydrazine gas. Water content in the liquid source formulation has reached purity levels of less than 50ppm, or <1.0ppm in the gas phase. BRUTE Hydrazine delivers gas phase hydrazine with purity levels comparable to semiconductor grade ammonia.
Hydrazine Gas for Titanium-Nitide ALD
BRUTE Hydrazine is an excellent nitride source for low temperature ALD for titanium-nitride formation. Titanium-nitride is used as both contact barriers and liner material.
Read More about Titanium-Nitride ALD
Hydrazine Gas for Low Temperature Nitridation
BRUTE Hydrazine is an excellent source for nitrides in in low temperature ALD applications. Advanced materials for semiconductor manufacturing require both low temperature and low resistivity. BRUTE Hydrazine is highly reactive at the temperatures required for these new advanced materials.
Read More about Low Temperature ALD
More Information on BRUTE Hydrazine
For more information about BRUTE Hydrazine, fill out an information request form or contact RASIRC directly.