Polymide Processing

S-Cubed’s coat and develop systems are designed to exceed the uniformity requirements of fabs that use viscous chemistries.

Polyimide Film Processing

Polyimides are one of the most difficult resist materials to process, because of their high viscosities and the use of strong solvents. Accordingly, tools used to coat Polyimides should have a simple and robust design. This design should keep the tool operational and clean despite the difficulties implicit in handling and processing this material.

Polyimide spin coating requires an enhanced solvent ambient during ramp up. The dispense arm should be positioned radially and in height with the spinning wafer. Process control is dependent on the spin speed and timing.

Soft baking of Polyimides requires ramping in a hotplate oven that does not reflux solvent effluent on the wafer and does not require hotplate oven cleaning. Finally, a means of controlling the develop process is required to ensure control of the final CDs.  S-Cubed’s systems, Figure 1, meet these requirements like no others. 

The Spin Bowl

Controlling solvent concentration in the ambient is essential to ensure a uniform coating while minimizing polymer consumption. Exhaust is minimized during the ramp up of Polyimide to create the required solvent rich ambient. Subsequently, exhaust is maximized while casting the material to create a solvent poor environment. S-Cubed’s programmable exhaust control allows the exhaust to be drawn directly from the bowl or from the module during the

coating process. S-Cubed’s techniques have proven to outperform conventional spinning cups/tops on resist bowls by reducing polymer consumption and keeping the process chamber cleaner.

During the high-speed spin coating of polyimides, a polyimide aerosol will form. The bulk of the aerosol is exhausted, but a tiny amount can deposit on the back of the wafer. Unlike with photoresist these polyimide deposits are very difficult to remove using solvents. Without post processing to remove this residue material the resultant device can have “hot spots”. S-Cubed has invented a process where the back of the wafer is completely protected from aerosol contamination. This process uses the combination of a physical barrier, liquid seals, and pressurized gas. *   

Unparalleled process flexibility and control is achieved by simultaneously controlling the radial position and height of the dispense with respect to the wafer. S-Cubed’s proprietary polyimide dual needle develop system, Figure 2, creates exceptional uniformity and increased throughput.

When polyimides dry they are very difficult to remove, complicating spin bowl cleaning. S-Cubed’s new self-cleaning spin bowl technology accounts for these difficulties. This new technology includes a programmable chuck height during handling and processing which minimizes cleaning costs and time, while ensuring a defect free process.

*Patent applied for

Thermal Modules

Our proprietary design ensures the hotplate chamber remains clean by prohibiting effluent to condense in the chamber. Servo motor-controlled hotplate pins have programable heights and speeds allowing for a myriad of temperature profiles. The hotplate pin height precision, 8 um total range, ensures the same programmable thermal profile wafer to wafer and lot to lot.

Some polymers, especially when spin-cast very thick, require long Post Apply Bake (PAB) times. S-Cubed has invented the first 8 wafer convection oven that offers a higher throughput, lower cost, and smaller tool footprint for long PAB times. *

These features and capabilities are available in both Flexi and Scene, Figure 3, systems. The decision between the Scene and Flexi systems should be based on wafer size, footprint, and throughput considerations. Do not hesitate to contact your local S-Cubed representative for more information.

^*Patent applied for

 

*1: Modules can have multiple process zones, spin modules can have 2 bowls, hotplate module 4 plates etc.

Document # 0-00086-10