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Sawatec Negative Resist Coater and Hotplate

Sawatec LSM-250 manual coater and HP-200 softbake station for negative tone photoresists HP-200 station for post-exposure bake of negative resists

 

Introduction

Access login and booking

Processing of thick negative resists can last long. Booking the equipment is recommended in advance. Logging in at the CAE terminal will enable the spinner and both of the hotplates simultaneously.

Material orders

Doses of various resin can be ordered using the standard reservation form: http://cmiaccess.epfl.ch/reservation/reserv.php
Place order at least 24 hour in advance. The material is delivered in CMi-1 behind Zone 01 on top of the metal cabinet labeled SU8. For users who sign up only for "Temporary Access to CMi Clean Room", send an e-mail to the photolithography section head to fix details of delivery.

Process Parameters

Sawatec coater line LSM250/HP-200 is dedicated to the processing of NEGATIVE TYPE SU8 photoresist. Modified SU8 based photoresist are admitted after approuval by the chemical safety board (see SOP procedure in general CMi BM+1 information page).

IMPORTANT:

Process recommendations download here: Runcard_SU8.xlsx.

Coater operation

The following display is visible during standby. Note the icons with gears on the right side: the one on the bottom is for automatic mode, and the top is used for editing recipes. In all cases, the 'Arm' button must be pressed in the bottom line of the display. If this is not activated, the arm will not cover the wafer during the spinning steps.

Standby display; check that the 'Arm' button is pressed. To start editing recipes, press the gear on the top. Next, click on the 'Mixer' icon on the bottom.

 

To enter the recipe editing menu, press on 'Train' button. The up and down arrows change the segments. For the last step, the 'End Seg.' button must be pressed. The door icon in the bottom right corner exits the editor menu.

Each segment consists of a time [s] and speed [RPM] steps. The end segment button must be turned on for the last step.

Hotplate operation

The gear icons on the right side set the main operating modes; the one on the bottom is for automatic mode, and the top one is to access the recipe editor menu. Please note that the 'Heating' and 'Cap' buttons must be always pressed, otherwise the heater and the cover accordingly will not operate during the process. The base temperature should always be set to 30 C.

Main display, with the 'Heating' and 'Cap' buttons always turned on. To start editing recipes, press the gear on the top. Next, click on the 'Mixer' icon on the bottom.

 

To enter the recipe editing menu, press on 'Train' button. Recipe editor page with time and temperature steps.

In the recipe editor menu, the VAC button should be pressed during the first segment; and the start/base temperature is defined in the first segment also. From the second segment, an end segment button is enabled which should be pressed for the last step.

Important: Loading sample on hotplate with protection foil

On this equipment no lift-pins are installed. To prevent permanent sticking of your sample to the protection plate always use a foil of cleanroom paper between hotplate and sample.

When ready, start the process by pressing the Start button on the main menu or on the machine. The cover will automatically open when the process is finished.

 

Important: Software bug workaround

The maximum step duration currently is 3276 sec. Any step with a longer time will result in maximum heating or cooling of the hotplate instead of the programmed ramp. If a longer duration is necessary, split into two steps.

Example: the PEB cooldown, 90C -> 30C in 5400 seconds, should be replaced with:

The SU8 Process Flow XLS file summary has been updated accordingly.