Working Principle, Characteristics and Application of Spin Coaters
Glue dispenser, also known as glue spinner, spin coater, and is mainly used as a film coating equipment for coating photoresist on wafers or in sol-gel experiments. The basic principle of a spin coater is to drip various adhesives on a high-speed rotating substrate, and use centrifugal force to make the adhesive coat evenly on the substrate. The thickness of the film is related to the viscosity of the adhesive, the viscosity coefficient between the adhesive liquid and the substrate, rotation speed, and spin coating time[1]. Generally, when the speed is above 2000rpm, most of the adhesive can be evenly distributed, and the stability and repeatability of the spindle speed are the key to determining the uniformity and consistency of film thickness.
Spin coaters are mainly used in the fields of micro-processing of micro-electromechanical systems, biology, materials, semiconductors, plate making, new energy, thin films, optics and surface coating, as well as coating of samples, whose substrate can not be coated through dip coating or film scraping. There are usually two ways to fix samples: vacuum chuck and grooved sample plate. A vacuum device is required to fix the sample with a vacuum chuck, which is suitable for fixing substrates with smooth surface, good flatness, and no deformation under vacuum suction. The grooved sample plate is used for fixing soft, larger sized, irregular shaped substrates.
Models and features of spin coaters:
VTC-50A spin coater is controlled by a single chip computer with high anti-interference, and the rotation speed is very stable in the range of up to 1000 to 8000RPM. There are two working stages for coating --- in T1 low speed stage, the film liquid is gradually disperse and the process of adhesive injection is completed, while in T2 high speed stage, the film liquid is evenly spread on the surface of the substrate to form a film with uniform thickness, and the adhesive uniformity process is completed. A grooved PP sample plate is used to fix the substrate. Grooves of different shapes and sizes can be opened on the template (delivered together with the spin coater) according to the shape and size of substrates. It is easy to use and simple to operate, and does not damage the substrate. The maximum size of samples that can be fixed is 55mm×55mm.
VTC-100 vacuum spin coater comes standard with 3 vacuum chucks of different sizes. The substrate is fixed by means of vacuum chuck adsorption, and the equipment uses two-stage program to control the speed. There are two working stages for coating --- T1 low-speed stage for adhesive injection, and T2 high-speed stage for adhesive leveling. After film leveling, the vacuum pump continues to work for a period of time until the machine completely stops running, and the whole process of film coating ends. Speed range: 500-8000rpm, the maximum size of samples that can be adsorbed is φ100mm.
VTC-200 Vacuum spin coater uses vacuum chuck adsorption to fix samples. The equipment uses two-stage program to control the speed --- T1 low-speed stage for adhesive injection, and T2 high-speed stage for adhesive leveling. After film leveling, the vacuum pump continues to work for a period of time until the machine completely stops running, and the whole process of film coating ends. Speed range: 500-8000rpm, the maximum size of samples that can be adsorbed is φ200mm.
VTC-100PA vacuum spin coater can be used for the preparation of coating films of strong acid and strong alkaline coating solutions. The equipment is equipped with two vacuum chucks of different sizes as standard to fix samples. The equipment can store 12 sets of programs, and each set of programs contains 6 running stages. The rotation speed of the equipment differs in different operation stages, and is slowly raised to the limit speed, which is conducive to the uniformity of film on the sample surface, saving coating materials. Speed range: 500rpm-10000rpm, the maximum size of samples that can be adsorbed is φ100mm. (Top cover heating spin coater can be customized. )
The chamber of VTC-100PA-UV UV spin coater is made of PP, which can be used for strong acid and strong alkali solutions. The upper cover of this machine has the function of UV light radiation, which is suitable for adhesives sensitive to UV light. The chamber is equipped with air inlet holes, which can be used to input protective gas during the adhesive leveling process. The samples are fixed by means of vacuum adsorption. Equipped with a special centering tool, the sample can be easily placed in the center of the vacuum chuck to reduce vibration caused by eccentricity and avoid being thrown off. Speed range: 500rpm-10000rpm, the maximum size of samples that can be adsorbed is φ100mm.
VTC-200P vacuum spin coater is made of PP, which can be used for coating film preparation of strong acid and strong alkaline coating solutions. The sample is fixed by means of vacuum chuck adsorption. The equipment can store 12 sets of programs, and each program contains 6 running stages. The setting range of speed increase and decrease rate of each stage: 100 - 2000 rpm/s, the time range of each stage: 0 - 60s. The rotation speed of the equipment differs in different operation stages, and is slowly raised to the limit speed, which is conducive to the uniformity of film on the sample surface, saving coating materials. The upper cover of the chamber can be optionally equipped with a heating function, which is beneficial to the coating process of film materials with high viscosity. Speed range: 500-6000rpm, the maximum size of samples that can be adsorbed is φ200mm.
VTC-200PV vacuum spin coater can be used for coating film preparation of strong acid and strong alkaline coating solutions. This equipment can evacuate its chamber, so that the sample can be coated in a completely vacuum state, which is suitable for materials that are easily oxidized and deteriorated in the air. The equipment can store 12 groups of programs, each group of programs contains 6 running stages. The setting range of speed increase and decrease rate of each stage: 100 - 2000 rpm/s, and the time range of each stage: 0-60s. The rotation speed of the equipment differs in different operation stages, and is slowly raised to the limit speed, which is conducive to the uniformity of film on the sample surface, saving coating materials. Speed range: 500-6000rpm, the maximum size of samples that can be adsorbed is φ200mm.
Corresponding spin coaters can also be customized according to customer needs.
References:
[1] Shi Donglu, Zhou Wuzong, Liang Weiyao, editor-in-chief, Applied Research on High Temperature Superconductivity, Shanghai Science and Technology Press, 2008.10, p. 266