Pump Line 11/11/99 7:58 AM Page 1
WATLOW
INCREASE TOOL UPTIME AND PROCESS YIELDS
PUMP AND
GAS LINE
HEATING SYSTEMS 2 | Pump and Gas Line Heating Systems Problem Condensation forms in gas lines when temperatures and/or Lines must be heated uniformly to prevent condensation in the gas pressure falls below the delivery line or particle clogging in vapor state. the pump line. Both gas and pump lines have unique thermal challenges due to many factors condensation including poor conductivity of stainless steel, different thermal mass of plumbing components, or ambient temperature changes between the cleanroom and subfloor.
Unheated pump lines have sublimation buildup due to poor and uneven heating.
Heat trace can produce a ribboning effect of sublimation in areas that are uncovered.
Insufficient heating of ports results in clogged valves. Pump and Gas Line Heating Systems | 3 Solution Vapor Pressure At low vapor pressures, 12,000 15.00 controlling the gas line 11,000 Uniform temperature coverage of 14.00 temperature above the 10,000 13.00 the gas and pump line systems, 12.00 9,000 vaporization point will prevent 11.00 including ports, flanges, valves, 8,000 10.00 condensation from occurring in etc., where particle buildup might 7,000 9.00 the line. Condensation occurs at 8.00 occur results in increased process 6,000 7.00 different temperatures for yields and a reduction in 5,000 6.00
5.00 Pressure (Bar) various gases. Pressure (Torr) 4,000 unscheduled downtime. 3,000 4.00 3.00 2,000 Application specific tests 2.00 Boron trichloride (BCl3) 1,000 1.00 concluded in a minimum increase Tungsten hexafluoride (WF6) 0 0.00 0 20 40 60 80 100 Dichlorosilane (SiH2CI2) of 10 percent in performance yield Temperature °C Chlorine trifloride (CIF3) improvement and a 60 percent reduction in maintenance cycles. However, actual results will vary Buildup is not present in a pipe with each application depending after being properly heated with on chemistry, tool design, Watlow’s pump line heaters. The plumbing design and process heaters were removed and variables. inspected on a normal preventative maintenance (PM) schedule.
LPCVD Nitride Wafer Surface Defects Particle generation defects (Data collected from field installations; decrease as pump line actual results may vary) 4.5 temperature uniformity increase.
m) 4.0 Pump Line µ 3.5 Heating System 3.0 Installed 2.5 2.0 1.5 1.0 0.5 per Square Inch (>0.3 0.0 Particle Related Surface Defects 0 20 40 60 80 100 120 140 Number of Runs (Pump Line Heating System Installed at 60 Runs)
Heater Jacket Temperature Guide Process by-products exit the For Specific Semiconductor Processes chamber in vapor phase, but 100 sublimate in the foreline and 10 vacuum pump when gas Solid Phase temperatures drop, forming 1 solids.
0.1 Vapor Phase 0.01 (Recommended internal temperature for Aluminum Etch (AICI3) Foreline Pressure (Torr) specified pressure) PECVD Nitride (NH4) 2 SiF6 0.001 LPCVD Nitride (NH4CI) 20 30 40 50 60 70 80 90 100 110 120 130140 150 160170 180 190 200 Temperature °C 4 | Pump and Gas Line Heating Systems Integrated System Solution
One supplier for From gas cabinet to scrubber, Features and Benefits Watlow’s standard gas and pump line thermal components; Even heating up to 200¡C (392¡F) heating systems combine thermal for uniform temperature profiles one supplier for components that optimize chemical over the entire heated line vapor deposition (CVD) and metal thermal systems • Eliminates cold spots that result in etch process performance. With condensation or particle buildup in The solution to achieving the optimum unsurpassed system performance and the line temperature uniformity, Watlow can performance is through an intelligently Precision electronic temperature help reduce condensation and particle designed heating system. Unlike other controllers and software; flexible to buildup, reduce maintenance related companies that just make heaters, changing process requirements downtime and improve process yields. sensors or controllers, Watlow designs • Electronic controllers with PID This complete system is constructed and manufactures all of these thermal temperature algorithms provide from Watlow’s heaters, sensors and system components into a complete <1°C control stability controllers that meet UL®, CE, NEC system. Cleanroom compatible silicone and SEMI S2-93 safety requirements. rubber construction Working with a partner whose products When used in conjunction with are found throughout the semicon- Watlow’s communications software, the • Clean heaters will not contribute to particle generation ductor manufacturing process offers system offers engineers an ideal a single responsible supplier that solution for improving and monitoring System components meet a ¨ understands how thermal systems system performance. combination of UL , CE, NEC and fit within the whole process. By SEMI S2-93 safety specifications integrating innovative heating, sensing, • Construction materials and controlling and communications electrical circuit comply to UL®, CE technologies, Watlow accepts (EMI) and FM safety standards responsibility for the total thermal Environmental safety system while meeting the growing • Reducing particle buildup expectations for tighter temperature decreases potential of employee tolerances. exposure to hazardous materials during normal cleaning cycles Optional 94-VO flame retardant materials • Fire-safe 94-HB or 94-VO material
UL® is a registered trademark of Underwriter’s Laboratories, Inc. Pump and Gas Line Heating Systems | 5
Typical Applications Optimum Line Watlow designs and manufactures all thermal system components, including Gas delivery lines Heating and Process software, to work together resulting in • Boron trichloride, BCl3 Performance optimum system performance. Watlow’s • Chlorine trifluoride, ClF3 Both gas and pump lines have unique expertise in providing thermal • Dichlorosilane, (DCS), SiH2Cl2 thermal challenges due to many factors solutions allows engineers to utilize one • Tetra ethyl orthosilicate, TEOS including: poor conductivity of stainless supplier for complete thermal system
• Tungsten hexafluoride, WF6 steel, different thermal mass of plumbing needs including: components, or ambient temperature • Process gas line qualification • Cleanroom compatible heaters that changes between cleanroom and the Fore line and exhaust lines for cover the entire line CVD and metal etch subfloor. • Heaters that fit tightly to line • Low Pressure Chemical Vapor The secret to achieving the optimum components, eliminating cold spots Deposition (LPCVD) — TEOS, performance is through an intelligently from loose-fitting heaters or Ti Nitride designed heating system. uncovered lines • Plasma Enhanced Chemical Vapor • Heaters can be customized with Deposition (PECVD) — TEOS, distributed watt densities, so lighter Ti Nitride, Tungsten, Oxynitride and heavier component parts are Plasma Etch Heated Delivery Lines heated uniformly • Aluminum etch Process • Electronic temperature controllers • Tungsten etch Tool and integral thermocouple sensors to provide stable temperature control • Safety limit controllers that meet Valve Manifold FM and SEMI S2-93 guidelines • Communications and software that can network with the tool or plant- wide LAN system
Remote Gas Delivery System
Heated Fore Line
Only Watlow supplies complete line heating solutions from gas cabinet to scrubber. Heated Transition Bellows
Heated Flange
Heated Exhaust Line
Heated Scrubber Isolation Valve
Temperature Control System Dry Pump 6 | Pump and Gas Line Heating Systems Modular Pump Line Heaters
The tight contact fit of Watlow’s pump line heaters provide superior, uniform heating of transfer lines. Agency Certification, • 120 and 208VÅ(ac) standard. Consult factory for other voltages Recognition • Power lead wires: 102 mm (4 in.) Compliance and #18 AWG UL® 1180/CSA Teflon® Approvals insulated, rated 10A, lead wire pair encapsulated in reinforced silicone (Contact factory for specific application and approvals.) rubber sleeving • Heaters interconnectable up to a • Complies with SEMI S2-93 standards 10A circuit • UL® recognized for U.S. and • New low watt density: Canadian safety standards 1-2 inch diameter, • CE 0.23 W/cm2 (1.5 W/in2) • NEC (National Electrical Code), 3-4 inch diameter, Article #427-23 0.19 W/cm2 (1.25 W/in2) General Specifications • Heater and jacket material: Sensor Pocket™ built-in to all reinforced silicone rubber fabric straight length heaters 76 mm • Color: (3 in.) long and greater; one per Insulation and outer jacket: gray heater. Heater: red-orange • Snap type fasteners: 13 mm (0.5 in.) nominal diameter metal construction with nylon cover; maximum Silicone Rubber operating temperature 200°C (392°F) Outer Jacket Snap Fastener • Velcro® fasteners available • See next page for available options