SiN_x PECVD Process

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Material Properties and Applications of Silicon Nitride (SiN_x)

Silicon Nitride (SiN_x) is a chemical compound of the elements Silicon and Nitrogen.
SiN_x has unique chemical and mechanical properties including low moisture and oxygen permeation, good electrical insulation and low thermal expansion.

For device fabrication, this material is used for various purposes.
• Passivation
• Insulation layer
• Mask for dry etching and ion implantation

By adjusting process recipe (pressure, RF power and etc.), SiN_x film properties (wet etch rate, refractive index, film stress and etc.) can be controlled.
SAMCO offers both Anode PECVD and Cathode PECVD process solutions for SiN_x thin film deposition.
For more detail on Cathode PECVD technology, please visit our Featured Solutions Page.

Conformal SiN_x Passivation Film Deposition

SiH₄ based SiN_x film was deposited for passivation of organic light emitting diode (OLED) fabrication, using an anode-coupled PECVD system. The film showed excellent step coverage on a structure over 90° step.

Deposition Temperature : 100°C
Film Thickness : 1.16 µm
Deposition Rate : 23.3 nm/min

SiN Film Deposition with Excellent Step Coverage

Control of SiN_x Film Properties

SAMCO’s SiN_x PECVD technology shows a highly-controllable wide process window and reproducibility with adjustment of process recipe.
The deposition processes are suitable for R&D to satisfy various demands on device fabrication.

Film Stress

Process Pressure v.s. Film Stress
SiH₄ based SiN_x using an anode PECVD system

Refractive Index

$Refractive Index Control of SiN Film$

NH₃ Flow Rate v.s. Refractive Index
SiH₄ based SiN_x using an anode PECVD system

Wet Etch Rate

Stage Temperature v.s. Wet Etch Rate
SiH₄ based SiN_x using an anode PECVD system

Safe SiN_x Plasma Deposition without Using SiH₄

Challenge in SiH₄ Based SiN_x PECVD Process

Silane (SiH₄) is widely used for PECVD processes to obtain high quality films. One of the drawbacks of a SiH₄-based PECVD process is the safety issue. SiH₄ is a flammable gas and easily ignite on contact with air. Also, the gas has toxicity to the human body. Therefore, device manufacturers need to take care of the gas use in production lines in the aspect of environment, health and safety (EHS).

SN-2 Based SiN_x PECVD Process

SAMCO provides SiN_x PECVD process solutions using liquid source called SN-2. SN-2 is an inorganic material which is available as liquid at room temperature. This material is not pyrophoric in air compared to SiH₄, and there is no need to heat up a container to use for deposition processes. SAMCO offers SN-2 based SiN_x deposition processes of both Anode PECVD and Cathode PECVD, depending on customers’ process requirements.

SN-2 based SiN_x can be used for an alternative of SiH₄ based SiN_x at existing wafer fabs concerning the safety issue. SiN_x films from different precursors were deposited using an anode-coupled PECVD system to investigate chemical bonds of the films. The FTIR transmittance spectrum showed peaks of Si-H, N-H and Si-N on the SN-2 based film, and they are seen as well in the spectrum of the SiH₄ based film. This means that the SN-2 based film has quality as good as SiH₄ based SiN_x film.

FTIR spectrum of SiH4 based SiNx and SN-2 based SiNx

SN-2 Based SiN_x Film as Hard Mask for Plasma Etching

One of the common applications of SIN_x film in today’s micro-electronics fabrication process is hard mask for plasma etching and ion implantation. SN-2 based SiN_x film is a good option in hard mask deposition for R&D labs which have severe restriction in hazardous SiH₄ use. SN-2 based SiN_x film shows controllable BHF etch rate as good as SiH₄ based film. BHF etch rate can be lineally controlled with precursor flow rate adjustment.

BHF etch rate of SiH4 based SiNx and SN-2 based SiNx

BHF etch rate of SiH₄ based SiN_x and SN-2 based SiN_x (against thermal oxide)

Controllable SN-2 Based SiN_x Film Properties

The SN-2 based SiN_x film shows excellent film properties. Film stress is lineally controllable with adjustment of deposition recipe. Furthermore, the step coverage is remarkably good. The film deposited on Al lines showed conformal coating on vertical sidewalls.

In addition to Anode PECVD process, SAMCO’s unique Cathode PECVD Technology will offer high-rate deposition of dense SiN_x film, utilizing ion bombardment driven by the negative electric field of the cathode electrode.