Improved planarization process for producing carriers with low step height

Abstract

A process to reduce step heights in planarization of thin film carriers in an encapsulation system. The improvements include using an adhesive tape having a thinner adhesive thickness and a stiffer tape for the film sealing the encapsulant on the carrier to result in a low step height surface transition between the carrier and the cured encapsulant. The composition of the encapsulant is modified to reduce the shrinkage upon curing of the encapsulant. The encapsulant may include an absorbent that absorbs the irradiation and cause the top surface to harden first compared to the bulk of the encapsulant, and / or a gas-emitting additive that creates gaseous products that expand upon irradiation to thereby reduce the shrinkage of the encapsulant upon curing. Alternatively, irradiation at very low incidence angle relative to the top surface of the encapsulant causes the top surface to harden before the bulk of the encapsulant.

Description

RELATED APPLICATIONS [0001] This application is a divisional application of U.S. patent application Ser. No. 10 / 109,929, filed Mar. 29, 2002.BACKGROUND OF THE INVENTION [0002] 1. Field of the Invention [0003] This invention relates generally to preparing thin films for etch patterning. More specifically, the invention relates to preparing thin film substrates and encapsulating material for etch patterning to form the air-bearing surface of a slider. [0004] 2. Description of Related Art [0005] Conventional magnetic disk drives are information storage devices that utilize at least one rotatable magnetic media disk with concentric data tracks. They also utilize a read / write transducer for reading and writing data on the various tracks or separate read and write transducers as in the magnetoresistive and giant magnetoresistive heads that have become the trend in the data storage industry as a means of improving data storage density. Disk drives generally also have an air bearing slider ...

AI Technical Summary

Benefits of technology

[0019] The invention provides a different adhesive tape to be used during the planarization process. The contribution to the increase of step height as a result of the tape can be minimized when a tape having a thinner adhesive layer is used. Further, the invention replaces the compliant PVC backing the tapes used in existing processes with a stiffer material backing such as polyethylene terephthalate, or polyethylene or polyethylene copolymers.

[0020] Another cause for the creation of the step height is the shrinkage of the acrylic encapsulant during the irradiation process. The invention provides two approaches with respect to modifying the composition of the encapsulant in order to reduce the step height caused by the shrinkage. First, the preferred approach is to include absorbents in the formulation of the encapsulant. The absorbents absorb the irradiation, thus reducing the curing effect. The presence of the absorbents also causes the top surface, which is the first surface of the encapsulant to be exposed to the UV light, to harden first compared to the bulk of the encapsulant. When the top surface hardens first and thus is fixated in its position, the contribution to the increase in step height as a result of the further shrinkage in the bulk of the encapsulant below the top surface will be minimized. The absorbent can be a bleachable or unbleachable dye (such as Curcumin), or it can even be photo-initiators. The second approach is to add a gas-emitting additive into the encapsulant, which will be converted into gaseous products upon irradiation. During the radiation, the additive will expand and form bubbles within the encapsulant, thus reducing the shrinkage of the encapsulant in volume.

Problems solved by technology

Another cause for the creation of the step height is the shrinkage of the acrylic encapsulant during the irradiation process.

The absorbents absorb the irradiation, thus reducing the curing effect.

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