Reactive Plasma Jet High‐Rate Etching of SiC

Abstract

The material removal of SiC utilizing a 2.45 GHz microwave‐driven plasma jet source in comparison with a 13.56 MHz RF excited plasma jet source at atmospheric pressure has been investigated. A coaxial nozzle with a central tube for helium, CF4 and O2 feeding the plasma and the outer ring‐shaped nozzle for N2 to shield the plasma jet from the surrounding air is applied. Additionally an O2 gas flow is provided and its effect on the etching rate is discussed for varied [CF4]/[O2] ratios. By optimizing the ratio of CF4 and O2 gas flow an improvement in etching rates and a change in surface roughness have been found. An increase of the etching rate with a decrease of the CF4 ratio has been detected for both jets. The etching rate of the microwave excited jet has been improved additionally by heating the SiC sample up to 350 °C.

High-temperature etching of SiC in SF6/O2 inductively coupled plasma

“…on/in the silicon carbide substrate. As of today, there is a fairly large variety of techniques for the processing of silicon carbide that allow, to some extent, to solve the following problem: wet etching; etching in solvents, stimulated by femtosecond laser; plasma etching; etching in plasma atmospheric discharge; plasma jet processing, and etc [15][16][17][18][19][20][21][22][23][24][25] . The choice of silicon carbide processing method is determined by the specific target, but nevertheless any of the methods must meet a number of general requirements: minimal defect formation on the surface of the etched profile, high etching rates, and high directionality of the processed window during the etching process.…”

Etch Mechanism and Temperature Regimes of an Atmospheric Pressure Chlorine-Based Plasma Jet Process

“…One of the drawbacks of PJM is the limited choice of materials, since the material removal process is based on a purely chemical mechanism that converts the solid substrate surface to gaseous compounds. So far mostly etching processes for silicon and silicon‐based materials, such as fused silica, Si 3 N 4 , or SiC have been investigated using fluorine‐based chemistry (e.g., using CF 4 and SF 6 as precursor gases) . Extending the choice of reactive gas components opens up a whole new range of materials that can be plasma jet processed.…”

“…Optical surfaces of ultimate precision have become indispensable for a broad spectrum of applications ranging from high quality imaging optics, over custom shaped freeform optics for research applications, space applications, and synchrotron optics to extreme ultra-violet lithography for the latest generation of semiconductor devices. [1][2][3] Besides the ongoing improvement of traditional, mechanicalabrasive surface figuring methods like grinding or polishing, alternative technologies for deterministic optical manufacturing employing sub-aperture tools based on ion beams and plasma jets have been developed, circumventing limitations regarding the reachable form accuracy surfaces. Plasma Jet Machining (PJM) technology, which is addressed in this work, is capable to fabricate a wide range of complex optical surface shapes (e.g., aspheres, acylinders, toroids, freeforms) with form accuracy down to the nanometer, with the qualification of being measureable.…”

“…So far mostly etching processes for silicon and silicon-based materials, such as fused silica, Si 3 N 4 , or SiC have been investigated using fluorine-based chemistry (e.g., using CF 4 and SF 6 as precursor gases). [2,5] Extending the choice of reactive gas components opens up a whole new range of materials that can be plasma jet processed. It is well known from semiconductor processes that chlorine containing plasmas are suitable for etching metals, such as titanium or aluminum, or oxides like Al 2 O 3 .…”

Atmospheric Pressure Plasma Processing of Fused Silica in Different Discharge Modes

“…Schindler et al studied the relationship between the removal rate of quartz and the substrate temperature [13] . Eichentopf et al researched the dependence of the removal rate of SiC on the gas mixtures and sample temperature [14] . Takino et al studied the effect of the gap distance between the electrode and the workpiece surface on the removal rate of synthetic silica glass [15] .…”