Spin Coating

Cee 100x spin coater

Manual Here

SOP here

 

The Cee Model 100 and 150 spinner module incorporates a stainless steel spin bowl. The spin bowl drain and

exhaust connect, through Teflon (PTFE) tubing, to the main utilities bracket on the rear of the machine. The

main drive spindle for the spin chuck is made of hardened, corrosion-resistant, alloy steel. The spindle is

driven by a toothed belt and a servo motor. An integral optical encoder provides feedback for the closed-loop,

digital, motor control system.



Spin Coating Process Theory  

Spin coating has been used for several decades for the application of thin films. A typical process involves

depositing a small puddle of a fluid resin onto the center of a substrate and then spinning the substrate at high

speed. Centripetal acceleration will cause the resin to spread to, and eventually off, the edge of the substrate.

Final film thickness and other properties will depend on the nature of the resin (viscosity, drying rate, percent

solids, surface tension, etc.) and the parameters chosen for the spin process. Factors such as final rotational

speed, acceleration, and fume exhaust contribute to how the properties of coated films are defined.

One of the most important factors in spin coating is repeatability. Subtle variations in the parameters that

define the spin process can result in drastic variations in the coated film. The following is an explanation of

some of the effects .of these variations.



Spin Coating Process Description

A typical spin process consists of a dispense step in which the resin fluid is deposited onto the substrate

surface, a high speed spin step to thin the fluid, and a drying step to eliminate excess solvents from the

resulting film. Two common methods of dispense are Static dispense, and Dynamic dispense



Static dispense is simply depositing a small puddle of fluid on or near the center of the substrate. This can

range from 1 to 10 cc depending on the viscosity of the fluid and the size of the substrate to be coated. Higher

viscosity and or larger substrates typically require a larger puddle to ensure full coverage of the substrate

during the high speed spin step.



Dynamic dispense is the process of dispensing while the substrate is turning at low speed. A speed of about

200 rpm is commonly used during this step of the process. This serves to spread the fluid over the substrate

and can result in less waste of resin material since it is usually not necessary to deposit as much to wet the

entire surface of the substrate. This is a particularly advantageous method when the fluid or substrate itself

has poor wetting abilities and can eliminate voids that may otherwise form.



After the dispense step it is common to accelerate to a relatively high speed to thin the fluid to near its final

desired thickness. Typical spin speeds for this step is 1000 to 2000 rpm, again depending on the properties of

the fluid as well as the substrate. This step can take from 10 seconds to several minutes. The combination of

spin speed and time selected for this step will generally define the final film thickness.



In general, higher spin speeds and longer spin times create thinner films. It is not recommended that the

parameters of this step be adjusted for spin times of less than 30 seconds. The spin coating process involves a

large number of variables that tend to cancel and average out during the spin process and it is best to allow

sufficient time for this to occur. It is common for very viscous films tu require several minutes to thin out and

to achieve a uniform coat thickness across the substrate.



Theory of Operation

A separate drying step is sometimes added after the high speed spin step to further dry the film without

substantially thinning it. This can be advantageous for thick films since long drying times may be necessary to

increase the physical stability of the film before handling. Without the drying step problems can occur during

handling, snch as pouring off the side of the substrate when removing it from the spin bowl. In this case a

moderate spin speed of about 25% of the high speed spin will generally suffice to aid in drying the film

without significantly changing the film thickness. Each program on a Cee spin coater may contain up to ten

separate process steps. While most spin processes require only two or three, this allows the maximum

amount of flexibility for complex spin coating requirements.