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Solvent Atmosphere Coating Processes

IP.com Disclosure Number: IPCOM000075840D
Original Publication Date: 1971-Nov-01
Included in the Prior Art Database: 2005-Feb-24
Document File: 1 page(s) / 11K

Publishing Venue

IBM

Related People

Canty, RA: AUTHOR [+4]

Abstract

Spin coated disks as used in memory disk applications often exhibit a "ramp" effect, where the thickness of the coating at the I.D. of the disk is thinner than at the O.D. of the disk. The ramp is generally linearly increasing from ID to OD.

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Solvent Atmosphere Coating Processes

Spin coated disks as used in memory disk applications often exhibit a "ramp" effect, where the thickness of the coating at the I.D. of the disk is thinner than at the O.D. of the disk. The ramp is generally linearly increasing from ID to OD.

Control of the ramp effect is achieved by controlling the solvent atmosphere during the spin coat process, which normally is done in an air atmosphere. By controlling the amount of solvent in the atmosphere surrounding the disk, solvent evaporation from the spinning disk is controlled, affecting the time during which the coating is in the liquid state and hence the ramp gradient.

In one embodiment, solvent similar to that in the coating is introduced into a coating booth, having a controlled volume chamber, after initial disk coating occurs. By controlling saturation of the atmosphere during spin drying, ramp of gradient is controlled. In another example, air is injected into the booth after passing a solvent supply and blending with it by the venturi effect. By this means, no solvent droplets are introduced into the coating chamber.

In another embodiment, a second disk is placed immediately above but not in contact with the disk to be coated. After coating operations, both disks are spun together to dry the coating. The close proximity of the second disk to the first creates a built-in solvent atmosphere of the evaporating solvent from the first disk. Further atmosphere control is afforde...