Quartz Glass Built for the Fab Environment
Every wafer that leaves a modern semiconductor fab has passed through quartz glass at some point in its journey. FGQuartz has spent twenty years engineering the tubes, boats, injectors, and vessels that make that journey possible — manufacturing from Lianyungang, China and supplying fabs worldwide.
20 yrs Semiconductor Manufacturing
Extreme Thermal Stability
Survives repeated furnace ramp cycles · no dimensional creep at process temperatures
Chemical Inertness
Resistant to H₂SO₄, HNO₃, HCl, H₂O₂ · will not react with process gases
Contamination Control
High-purity SiO₂ prevents metallic contamination of the silicon lattice
Dimensional Precision
Low thermal expansion keeps wafer slot geometry consistent across thousands of cycles
Optical Transparency
Clear grade transmits UV through IR · enables in-situ pyrometry and UV processing
Thermal Shock Resistance
Near-zero CTE prevents crack propagation during rapid temperature transitions
Est. 2005
Lianyungang, Jiangsu, China
Americas · Europe · Asia-Pacific
Full Custom CNC
Prototype to production volume
In-house R&D
Process & material engineering team
Semiconductor Quartz Glass Components
FGQuartz manufactures the complete range of front-end quartzware required across thermal, CVD, and wet-cleaning process modules. Standard geometries ship from stock; custom components are produced to drawing from the same facility.
Process & Diffusion Tubes
The backbone of every thermal furnace stack. FGQuartz process tubes are produced in both horizontal and vertical configurations for oxidation, diffusion, annealing, and CVD applications. Available in clear fused silica for pyrometry-enabled furnaces and in opaque grade for insulating liner duty. Tube ends are supplied plain, flanged, or ground to sealing surfaces depending on the furnace interface required.
Wafer Boats & Carriers
Wafer boats must hold dozens of wafers at precise, repeatable slot positions through thousands of furnace cycles without warping, particle generation, or slot-edge chipping. FGQuartz boats are CNC-machined from solid quartz blocks rather than assembled from separate rods, giving superior structural rigidity and eliminating the weld joints that can become contamination or fracture points. Flat-slot, V-groove, and U-groove profiles are available across all standard wafer sizes.
Gas Injectors & Injector Rings
Gas uniformity across a furnace load directly affects film thickness uniformity and electrical yield. FGQuartz injector tubes and injector rings are drilled with diamond tooling to customer-specified hole patterns, enabling precise control of the local gas flow profile. Compatible with nitrogen, oxygen, HCl, TCA, SiH₄, and other standard process gases used in diffusion and CVD furnaces.
Flanges, Endcaps & Liners
Furnace peripherals that are often overlooked but just as critical as the process tube itself. FGQuartz manufactures tube flanges and endcap assemblies with polished sealing faces for O-ring or knife-edge vacuum interfaces. Furnace liners in opaque quartz provide thermal insulation and protect the inner tube. All hardware is dimensionally matched to the process tube grade it accompanies, ensuring compatible thermal expansion during cycling.
Quartz Tanks & Wet-Bench Vessels
Wet cleaning is the most chemically aggressive environment in the fab, and quartz tanks must survive repeated exposure to hot piranha, SC1, SC2, and HF-based cleaning sequences. FGQuartz tanks are fabricated by fusion welding — no adhesives, no gaskets, no metallic fittings that could leach contamination. Overflow weirs, drain spigots, and heater housings are integrated directly into the quartz body.
Custom CNC-Machined Quartzware
New tool generations regularly require quartzware geometries that do not exist as catalogue parts. FGQuartz operates a dedicated CNC machining centre equipped with diamond and CBN tooling capable of turning, milling, drilling, and grinding fused silica into complex three-dimensional parts. Customers supply drawings in DXF, STEP, or IGES format — or send physical sample parts for reverse engineering. Prototype quantities down to a single piece are accepted.
Quartz Glass Across Every Front-End Process Module
Select a process module to explore which quartz components are involved and why quartz glass is the material of choice for that specific environment.
Diffusion Furnaces & Tube Furnaces
Thermal diffusion is one of the oldest — and still most widely used — steps in semiconductor manufacturing. Boron, phosphorus, arsenic, and antimony are driven into the silicon crystal lattice at high temperatures to create the doped regions that define transistor behaviour. The quartz process tube is the vessel in which this chemistry takes place, and its purity is non-negotiable: any metallic impurities that leach from the tube wall at process temperature will introduce unintended dopant atoms that ruin the device.
Gate oxide growth by thermal oxidation places even higher demands on tube cleanliness. The silicon–silicon dioxide interface quality is exquisitely sensitive to trace sodium, iron, and other transition metals. Fabs typically maintain dedicated tube sets for oxidation, diffusion, and annealing to prevent cross-contamination between processes.
FGQuartz diffusion tubes are produced in diameter ranges compatible with 150 mm, 200 mm, and 300 mm wafer batches. Matching endcap and flange hardware is supplied from the same quartz grade to ensure thermally compatible behaviour during furnace cycling.
Chemical Vapour Deposition Furnaces
CVD processes deposit thin films of polysilicon, silicon nitride, silicon dioxide, and tungsten onto wafer surfaces by decomposing reactive gas species at elevated temperatures. Low-pressure CVD (LPCVD) is carried out in the same horizontal tube furnace geometry as diffusion, but at sub-atmospheric pressures that improve film uniformity across the wafer batch.
The gas injector is the most geometry-sensitive component in an LPCVD system. Because the reactive gas is consumed as it flows through the tube, a simple end-feed design results in thicker films at the gas inlet end and thinner films at the exhaust end. Injector tubes with carefully positioned holes distribute the gas source uniformly along the tube length, compensating for depletion and producing within-batch film thickness uniformity acceptable for production. FGQuartz manufactures injector tubes and rings to customer-specified hole patterns, which are typically derived from computational fluid dynamics modelling of the specific tool.
For PECVD and atmospheric CVD, quartz plays a secondary but important role as the material for process chamber liners, showerhead bodies, and handling hardware that must survive the combination of reactive chemistry and elevated temperature.
Annealing & Thermal Treatment
After ion implantation, the silicon crystal is heavily damaged and the implanted dopant atoms are mostly sitting in interstitial sites rather than substituting into the lattice. Annealing drives atomic rearrangement that heals crystal damage and activates the dopant electrically. Rapid thermal annealing achieves this in seconds; furnace annealing takes minutes to hours but treats larger batches simultaneously.
In furnace annealing, opaque quartz liners surrounding the process tube act as thermal baffles, reducing the temperature gradient along the tube length and improving wafer-to-wafer thermal uniformity. The closed-cell foam structure of opaque quartz absorbs and re-emits thermal radiation rather than transmitting it, making it an effective insulating barrier between the heating elements and the process zone.
For RTP systems, quartz acts as the window between the lamp array and the wafer, transmitting the intense near-infrared radiation of halogen or arc lamps to the silicon surface. The optical quality of the quartz window affects the uniformity of the radiant flux pattern and therefore the uniformity of temperature across the wafer.
Wet Chemical Cleaning
Wet cleaning is performed at multiple points in the wafer flow — before and after deposition, after photolithography, and as final cleaning before thermal steps — because particle contamination and surface chemical states directly affect yield. The RCA clean sequence removes organic, metallic, and oxide contaminants using hydrogen peroxide with ammonia or hydrochloric acid at elevated temperatures. Piranha strips heavy organics. HF removes native oxide.
Quartz tanks are the industry-standard vessel for all of these chemistries because fused silica is inert to all of them except HF. Where HF cleaning is required, specially selected high-purity quartz grades with minimal subsurface micro-defects are used, as HF attacks grain boundaries and surface irregularities preferentially.
All FGQuartz wet-bench tanks are fusion-welded from flat quartz plate — no adhesive joints, no metal fittings inside the chemical zone. This construction eliminates the contamination and failure modes associated with PTFE-gasketed or epoxy-bonded assemblies.
Silicon Epitaxial Growth
Epitaxial silicon deposition grows a single-crystal silicon layer on the wafer surface with a precisely controlled dopant profile. The process demands an extremely clean thermal environment because any contamination of the growing surface at the atomic level manifests as electrically active defects that degrade device performance.
In barrel-type epitaxial reactors, a large quartz bell jar encloses the susceptor and wafer stack. The bell jar must be transparent to the near-infrared radiation from the surrounding lamp array, allowing the susceptor to be heated radiatively while the jar itself remains relatively cool. In situ HCl etching is used periodically to clean the reactor walls, so the quartz bell jar must withstand this treatment without generating particles.
FGQuartz supplies bell jars, liner tubes, and auxiliary quartz hardware for both atmospheric and reduced-pressure epitaxial reactors, working to OEM replacement specifications or custom designs provided by the customer.
Optical Fiber Preform Manufacturing
Optical fiber begins as a cylindrical preform — a solid glass rod with a precisely engineered refractive index profile — that is later drawn into fiber tens of kilometres long. The three dominant preform manufacturing methods all rely on quartz glass: MCVD deposits glass layers inside a rotating substrate tube; OVD builds the preform from the outside in; VAD grows the preform axially on a rotating target.
MCVD substrate tubes must meet tight diameter and wall thickness uniformity requirements because any geometric deviation in the substrate propagates into the deposited core-cladding structure and affects the fiber’s single-mode cut-off wavelength and chromatic dispersion profile. FGQuartz supplies MCVD substrate tubes in standard telecom and specialty fiber dimensions aligned to OEM lathe requirements.
Reaction tubes, mandrels, and handling hardware for OVD and VAD processes are also produced to customer specification, drawing on the same precision CNC capabilities used for semiconductor quartzware.
Understanding Quartz in the Semiconductor Process
Selecting the right quartz component is not only about dimensions. Grade selection, surface preparation, and handling all affect the cleanroom outcome.
Clear vs. Opaque Quartz: Choosing the Right Grade
Clear fused silica and opaque quartz are the same base material — silicon dioxide — but opaque quartz is processed to contain a uniform distribution of microscopic voids that scatter and absorb light rather than transmitting it. Clear quartz is used where light transmission matters: process tubes observed by pyrometry, UV lamp envelopes, and RTP windows. Opaque quartz is used where thermal insulation and low emissivity matter: furnace liners, baffles, and spacers that must shield surrounding components from radiant heat. Mixing grades incorrectly leads to unexpected heat leakage and temperature non-uniformity across the wafer batch.
Low-OH vs. Standard-OH Quartz: The Hydroxyl Question
Hydroxyl (OH) groups incorporated into the quartz network during synthesis affect the material’s optical behaviour in two important regions. High-OH (wet) quartz has superior UV transmission — relevant for deep-UV lithography, excimer laser optics, and UV sterilisation. Low-OH (dry) quartz is the right choice for LPCVD and high-temperature furnace applications where residual moisture release could affect film chemistry or introduce oxygen contamination. Specifying the wrong OH grade for a furnace application can result in subtly elevated moisture levels in the process ambient that affect film properties across the entire batch.
Quartz Tube Lifecycle and When to Replace
Quartz process tubes do not last indefinitely. Repeated thermal cycling causes stress accumulation, and exposure to HCl cleaning cycles, dopant source vapours, and deposition gases gradually modifies the inner surface. Devitrification — a crystallisation process that produces a milky, opaque surface layer on clear quartz — can occur when tubes are held at high temperatures for extended periods, particularly in the presence of alkali contamination. Devitrified quartz is structurally weaker and generates particles. Visual inspection for surface milkiness, cracking at flange joints, and slot-edge chipping on wafer boats are the key maintenance triggers. Proactive replacement is strongly preferable to running tubes to failure in a production environment.
Pre-use Cleaning and Qualification Protocols
New quartz components must be cleaned and thermally pre-conditioned before use in a production furnace. The standard protocol involves acid cleaning followed by DI water rinse and drying, then a high-temperature pre-bake in a dedicated qualification furnace before the component enters the production tool. This removes surface contamination from manufacturing and machining and allows the quartz to outgas adsorbed water and atmospheric contaminants before it is exposed to product wafers. FGQuartz can supply components pre-cleaned to incoming inspection standards, reducing the lab work required at the customer site.
Natural vs. Synthetic Fused Silica
Fused silica is produced by two fundamentally different routes. Natural fused silica is made by melting high-purity natural quartz crystals and achieves very low metallic impurity levels through careful raw material selection. Synthetic fused silica is produced by flame hydrolysis or chemical vapour deposition of silicon-containing precursors such as SiCl₄, achieving the highest purity levels achievable. Synthetic grades command a significant price premium and are used in the most demanding optical applications. For the majority of thermal furnace quartzware, natural high-purity fused silica provides the required contamination performance at a significantly more competitive cost. FGQuartz advises customers on grade selection based on the specific process node and contamination budget.
Handling and Storage Best Practices
Quartz glass components are fragile, and contamination from bare-hand contact — sodium and potassium from skin oils — can persist through cleaning and reintroduce contamination during high-temperature processing. All quartz components should be handled with clean nitrile or latex gloves in a cleanroom or clean-bench environment. Storage should be in sealed polyethylene bags away from HF vapour, humidity, and vibration. Tubes should be stored horizontally on padded supports to prevent long-term sag under their own weight. FGQuartz packages all outgoing components in cleanroom-grade materials and includes handling guidance with each shipment.