In semiconductor manufacturing, the drying process after wafer cleaning directly impacts chip yield and performance. The Spin Dryer (semiconductor centrifugal dryer) efficiently removes residual liquids (such as deionized water or organic solvents) from the wafer surface through the centrifugal force generated by high-speed rotation, making it a core equipment for ensuring the quality of subsequent processes.
I. Core Function: Solving Key Issues in Wafer Drying
After cleaning, wafers are often covered with a large amount of liquid. If not thoroughly dried, the residual moisture may cause metal layer oxidation, particle contamination, or pattern defects due to uneven surface tension. Traditional hot air or infrared drying methods have issues such as temperature sensitivity (which can damage low-k dielectrics or photoresists), poor uniformity (insufficient drying at the edges of large-sized wafers), and secondary particle contamination. The Spin Dryer physically dries wafers through centrifugal force, quickly removing liquids under low-temperature and non-contact conditions, avoiding thermal stress and airflow interference. It has become an essential process for advanced process nodes (such as 7nm and below).
II. Working Principle: The "Microscopic Manipulation Art" of Centrifugal Force
The core design of the Spin Dryer is not complicated, but its requirements for precision and stability are extremely high. Its basic principle can be summarized as follows: the motor drives the wafer to rotate at a high speed (the typical rotational speed range is 1000 - 5000 RPM, which is adjusted according to the wafer size and process requirements), and the centrifugal force is used to throw the surface liquid towards the edge and detach it from the wafer.
III. Technological Evolution: Adapting to the Needs of Advanced Process Nodes
Early Spin Dryers only supported fixed rotational speeds and were suitable for mature process nodes above 180nm. As the process nodes shrink to 7nm, 5nm, and even 3nm, the wafer size increases (12 inches becoming the mainstream), the structure becomes miniaturized (line width in nanometers), and the materials become more sensitive (such as low-k dielectrics), driving the equipment upgrade:
Multi-stage Rotational Speed Control: Start at a low speed (such as 500 RPM) to avoid liquid splashing, gradually accelerate to the target speed (such as 3000 RPM) to ensure uniform drying, and stop at a slow speed to prevent residual liquid backflow.
Intelligent Parameter Adaptation: Integrated sensors (rotational speed, temperature, vibration) and control systems automatically adjust the rotational speed, time, and auxiliary gases (such as nitrogen purging) according to the wafer type (silicon-based/compound), cleaning solution composition (acid/alkali/organic solvent), and surface state (hydrophilic/hydrophobic).
Energy Conservation and Environmental Protection Optimization: Adopt high-efficiency motors, precise nitrogen control, and waste liquid recycling to reduce energy consumption and chemical consumption.
IV. Application Scenarios: Covering Key Nodes in Semiconductor Manufacturing
The application of the Spin Dryer is not limited to the drying after wafer cleaning. It is also widely used in the following scenarios:
Before the Photolithography Process: Dry the wafer before coating the photoresist (to ensure the perfect adhesion of the photoresist to the surface).
After Etching/Ion Implantation: Remove the residual etching gases or implantation by-products.
In the Packaging and Testing Process: Dry the substrate after chip cutting and perform surface treatment before wire bonding.
In the R & D Laboratory: Quickly dry small-batch samples and verify the process.
