Cleaning processes using ultra high purity chemistries require adequate pure equipment solutions with advanced surface and structural interaction. The hardware design focus is on the cleaning efficiency in variable structures at different aspect ratios. The effective removal of trace contaminants and particulates down into the Nano-meter scale can be achieved.
Etch processes for the different SC- materials require hardware optimized to the used high purity etch-chemistries. Low sigma variations of the etched structural dimensions from across chip, across wafer and wafer to wafer are the main target for wafer sizes up to 300mm. The effective removal of the etched materials in the structure is achieved by the optimized hydro-dynamic flow conditions in the equipment and the AP&S dryer concepts contribute to low particulate levels.
After etching, the pattern is a permanent part of the top layer of the wafer. The resist that has acted as an etch barrier is removed from the surface. Various chemistries (pending resist type) are in use to remove the different resists, while the hardware is optimized to achieve clean surface conditions and support low defect density targets post stripping.
The pattern of the resist is developed by the chemical dissolution of the unpolymerized resist region. Development will form in the resist layer a pattern with the exact dimensions designated during the circuit design process. Hardware features are optimized to the chemistries used as different chemical are needed for positive and/or negative tone resists.
Metal pattern etch technologies for Al, Ti, W and others. Complete removal of metals processes from device- or monitor- wafers for wafers up to 300mm diameter, using hardware tailored to the specific chemistries needed for each metal composite.
Flip chip bonding is of increasing importance to further device miniaturization. Under-bump metallization is deposited in electro-less deposition technology on Al-alloy and Cu- substrates. The UBM act as a electrical connection, have a barrier function and is a mechanical interconnection between substrate and solder ball. Batch and single wafer processes are capable to meet device requirements and process stability needed for volume production.
Metal-Lift-Off is a pattering process that eliminates the etch variation component. Wafers are processed through the development step, leaving a hole in the resist layer where a deposited layer is to be located on top of the resist and into the opening. Using ultra-sonic support the deposited layers are removed with the resist and the desired pattern is left on the wafer surface.
Water surface tension creates a unique condition when wafers are pulled slowly through a water surface. The tension draws the water away from the surface, leaving it dry. Using additional IPA and N2 this effect is enhanced at the water to water interface by the creation of a strong surface tension gradient (Marangoni drying).
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