Ceramics and glasses · Workhorse
Silicon carbide (CVD)
SiCvalues describe: CVD β-SiC
Why it wins
Showerheads, focus rings, susceptors: erosion products are process-native, so wafers see no foreign metal.
Why not the alternative
Metals contaminate; quartz is consumed and silicon-contaminates non-Si layers.
Properties
The values below are candidate: compiled from the sources named, not yet individually validated. Provisional provenance: Semiconductor chamber materials and plasma-resistant coating literature; CoorsTek, CeramTec, Kyocera technical ceramic data.
Wet cleaning
| Recipe | solvent, then SC-1 / SC-2 wet bench for fab parts, ultrapure rinse, spin dry |
|---|---|
| Forbidden | HF on SiSiC: it attacks the free silicon phase |
| Limit | the free-silicon content of the grade decides which chemistry is safe |
Vacuum and outgassing
| Outgassing, unbaked (10 h) | 5e-10 mbar·L/s/cm² |
|---|---|
| Outgassing, baked | 5e-13 mbar·L/s/cm² |
| Vapour pressure | none |
Temperature
| Bake, assembled | 450 °C |
|---|---|
| Vacuum degas | 1200 °C |
| Braze / H2 firing | 1400 °C |
| Metallurgical limit | service to 1600 °C inert; protective oxide above 1200 °C in air |
Thermal
| CTE | 4.2 ppm/K |
|---|---|
| Thermal conductivity | 120–200 sintered, 250–300 CVD W/m·K |
| Specific heat | 690 J/kg·K |
| Emissivity | 0.8–0.9 |
| Melting / softening | 2730 dec. °C |
Mechanical
| Strength | 400–550 flex MPa |
|---|---|
| Elongation | nil |
| Young's modulus | 410 GPa |
| Hardness | 2500–2800 HV |
| Density | 3.21 g/cm3 |
Electrical and magnetic
| Relative permeability | 1.0 |
|---|---|
| Resistivity | 1e2–1e6 Ω·cm, doping dependent |
Engineering
| Corrosion | outstanding in halogen plasma; the reason it displaced quartz |
|---|---|
| Joining | diffusion bonded or brazed; CVD grades coat graphite |
| Process notes | CVD grade is pore-free and takes an optical polish |
| Availability and cost | CVD long lead, sintered in stock |
Brazing
Sourced pairings
| With | Filler | Atmosphere | Expansion gap at set |
|---|---|---|---|
| Oxygen-free copper C10100 / C10200 / Kovar (FeNiCo) / Nickel and nickel plating / Austenitic stainless 304L / 316L / 316LN ESR / Titanium Gr 2 / Ti-6Al-4V / refractories (unspecified) | Ticusil | vacuum 1e-5 mm Hg or inert gas | 1.04 % at 780 °C Oxygen-free copper C10100 / C10200 on the outside over budget |
Preparation
- none
Compatibility
What documents state about this material faced with a filler metal, without the other member of the joint. A statement that names the exact filler comes first. A statement about a whole AWS class comes after it: a class covers dozens of alloys, so it is the weaker of the two, and the corpus never turns one into the other.
- listedCusilSchwartz names Cusil among the silver-base filler metals that are ductile and adaptable to brazing metals to silicon carbide.
Conditions and source
Book page 151, prose, section on new ceramic-metal and filler-metal combinations. The sentence names Cusil and Incusil together and lists four ceramics: Si3N4, PSZ, transformation-toughened Al2O3 and SiC. Only SiC and Cusil have an identifier at the corpus. Incusil is not written because the corpus carries three products under that name, Incusil 10, Incusil 15 and Incusil-ABA, and the sentence does not say which. Transformation-toughened Al2O3 is not written because it is a distinct engineered ceramic and the corpus alumina entry covers technical alumina 94 to 99.8 percent. The sentence says brazing metals to these materials without naming a metal, so no partner is recorded.
M. M. Schwartz, Brazing, 2nd edition, ASM International, 2003, chapter 4, Base Metals and Base-Metal Family Groups, DOI 10.1361/brse2003p063
Chapter 4 of the second edition, book pages 63 to 162 in the copy read, which treats base metals family by family and states metallurgical reactions, atmosphere limits and filler selection guides. It is a handbook chapter, not a qualification record. The page of each statement is carried by the entry that uses it, never by this registry line.
Chemical affinity
What documents state about a BINARY SYSTEM, one element of a filler metal faced with one element of this material. An affinity is not a verdict on a joint: a joint brings many binaries together at once, some helpful and some harmful, and what follows is the list of those the corpus can name. The count below is not written anywhere. It falls out of the crossing of this material's elements with the composition of every filler the corpus holds, so it grows on its own the day a binary enters the corpus.
Elements of this material: Si C, from the chemical name.
interfacial reaction that wets9 fillersTi against C1 source+1 statement
The two elements react at the interface and the product of that reaction is what the rest of the filler wets. This is the mechanism that makes active metal brazing work, and it is the only one of the six that a joint wants.
9 fillers: 35Au-62Cu-2Ti-1Ni, 48Ti-48Zr-4Be, 49Ti-49Cu-2Be, 56Zr-28V-16Ti, 71.5Ti-28.5Ni, Cusil-ABA, Cusin-1 ABA, Incusil-ABA, Ticusil
Conditions and verbatim
Printed page 862, closing paragraph on other nonoxide ceramics. The article states that titanium nitrides and carbides are known as the interfacial reaction products for titanium-containing active metal brazes. It immediately qualifies the reach of that statement, and the qualification is carried here rather than dropped: the wettability of such carbides and nitrides with metal liquids may be influenced by their stoichiometry, citing Ref 109. The article speaks of carbide ceramics. This corpus also holds two carbons, graphite and diamond, whose element is the same C, and the entry is served for them too because the reaction named is the one between titanium and carbon.
Source[A] Joining, in Engineered Materials Handbook Desk Edition, M. M. Gauthier editor, ASM International, 1995, pages 846 to 864, DOI 10.31399/asm.hb.emde.a0003056
Source conditionsHandbook article, consulted as a PDF whose printed page numbers run 846 to 864. The article is itself a digest of the Ceramics and Glasses volume 4 of the Engineered Materials Handbook, so its statements are second-hand summaries of the papers it cites by Ref number. The Ref numbers are kept in the conditions of each entry, because a reader who wants the primary measurement needs them.
Grades
| CVD SiC | wafer-adjacent purity: showerheads, focus rings |
|---|---|
| Sintered SSiC | structural parts away from the wafer |
| Reaction-bonded SiSiC | cheap and stiff, free Si limits plasma exposure |