The Lam4520XL is an enhanced version of VTTs pre-existing Lam4520. With added gas chemistry, dual-frequency, capacitively coupled electrode configuration, and increased pumping capacity, the tool is ideally suited for advanced oxide etch applications like MEMS and photonic hard-mask patterning steps. In particular, the contact via gas chemistry provides the ideal control of polymer necessary to achieve vertical sidewalls, yet retain exceptional selectivity to photoresist. Standard etch processes have thus been developed for hard-mask patterning, a more general purpose etchback, contact vias, and even an in-situ resist strip.
Process conditions and specifications
Process gases: CF4, CHF3, O2 (restricted due to electrode lifetime considerations), C4F8, CO, Argon, N2 (restricted use due to excessive chamber sputtering)
Process pressure: recipe Setpoint pressures can be as low as 0 mTorr, the actual Wafer Area Pressure will always be in the range of 40 - 100 mTorr, depending upon gas flow. RF Power: in 6 inch mode, the maximum bottom or top RF power is 1000W at 2 MHz. In 8 inch mode, the maximum top or bottom RF power is 1500W at 27 MHz
Allowed materials: oxide, silicon nitride, poly-silicon, photo resist
Gases and chemicals: CF4, CHF3, O2 , C4F8, CO, Argon
Safety Special Requirements
This tool has an Electrostatic chuck so wafers must have a standard 56 mm primary flat. Secondary flats are not allowed. Aside from monitoring etch rate, the process control team should note He clamp flow is in spec, typically in the range of 22-24 sccm for a weekly monitor wafer during etching with the weekly XL735 recipe. Excessively high He leak rate probably indicates a dirty ESC.