Tystar Tytan horizontal diffusion and LPCVD furnace

Where the Tystar Tytan fits

Tystar, based in California, builds horizontal furnaces sold as the Tytan series (sometimes written Titan). Tytan stacks typically hold up to four tubes, on full-size and smaller Mini Tytan frames, and are a standard fit in North American university nanofabrication facilities, where one stack often holds dry oxide, wet oxide, LPCVD nitride and LPCVD polysilicon. A used Tystar Tytan furnace suits a lab that wants batch thermal films with established recipes and straightforward maintenance.

Compared with a vertical furnace, a horizontal stack has a smaller ceiling height requirement and lets you service each tube independently. It does load wafers horizontally into a hot tube, so particle control depends on the paddle and loading speed. For the whole range of thermal tools, see thermal processing equipment.

Common configurations

Used Tytan systems arrive with very different tube sets. We list:

• process per tube and the gases plumbed to it
• tube diameter, boat type and wafer capacity
• LPCVD pump type, pressure control and trap
• loading method: manual, cantilever or automated
• host software generation and recipe backup

Atmospheric tubes for oxidation and anneal are the simplest to restart. LPCVD tubes need more work: pumps, pressure gauges, heated door seals and traps all need checking.

Tube history matters as much as hardware. A tube that ran boron or phosphorus doping should stay a doping tube, and a nitride tube carries deposit on its walls that limits how it can be reused. Ask the seller what each tube ran, for how long and when the quartz was last cleaned or replaced. If you plan to change a tube's process, budget for new quartzware and a fresh gas line rather than adapting the old ones.

What we inspect

Each tube is heated to process temperature and profiled across its flat zone. We check element resistance, thermocouple agreement and controller tuning. Gas lines are leak tested and mass flow controllers checked for zero and span. On LPCVD tubes we record base pressure and leak-up rate and inspect the cold trap and pump. The quartz tube, end caps and boats are inspected under good light for devitrification and cracks.

Wear points are the usual furnace items: elements that have aged unevenly, thermocouple sheaths, quartz damaged by deposit build-up, flange O-rings and paddle drives.

Refurbishment, moving and upgrades

Furnaces are heavy, and quartzware is fragile, so the way a Tytan is de-installed affects whether it works on arrival. Our post on moving a semiconductor tool and our de-installation and crating service describe how we separate tubes, elements and electronics for transport.

Refurbishment covers new elements and thermocouples where needed, quartzware cleaning or replacement, leak testing and calibration. Upgrades include host software and controller updates, automated loaders and dry pumps for LPCVD.

Facilities you will need

• Three-phase power with high current per tube, depending on configuration
• Cooling water for the scavenger and LPCVD pumps
• Clean dry air
• Nitrogen for purge and idle
• Process gases per tube, with toxic gas detection for LPCVD
• Scavenger and process exhaust, with abatement for LPCVD and doping tubes

Buying advice

Decide which films you need and whether you can keep tubes dedicated. Ask for profile and thickness data from the last owner if it exists. Check that your facility can supply the power and exhaust; hook-up and facilities is usually the critical path for a furnace installation.