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Post damascene laser ablation processing for personalization of cured polymers

IP.com Disclosure Number: IPCOM000238193D
Publication Date: 2014-Aug-07
Document File: 4 page(s) / 42K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for post damascene laser ablation processing for personalization of cured polymers. The method includes the fabrication of an in-polymer redistribution wiring layer using an open/plate/damascene process.

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Post damascene laser ablation processing for personalization of cured polymers

During the creation of a semiconductor device/chip/wafer, important features may be blocked, obscured, or prevented by the presence of a cured polymeric passivation film. This issue can be experienced when metal features are embedded into passivation films using damascene based processing, for example.

A variety of techniques can be applied to remove cured passivation materials. These have varied degrees of effectiveness depending on the chemistry of the polymer coating. A polymer coating can be opened using mechanical scraping techniques. The drawback is that this technique could easily cause mechanical damage to the electrical pad and other nearby features on the device. A polymer coating can be opened using ion bombardment. The drawback is that the device must be properly masked and, depending on the type of bombardment, damage can be caused to the underlying pads, or the process is slowed due to the buildup of non-organic components in the opening.

A polymer coating could be opened using chemical attack or a passivation dissolving chemistry. The drawback with this approach is that the device must be masked; chemistry may flow under the mask having a larger unintended impact on the polymer coating, and may corrode exposed features on the device.

Sharp electrical probes can be forced through the polymer coating. Some polymers are difficult to penetrate and the penetration of the polymer may cause unintended damage to the film. The probes might also damage the electrical pads or other features on the device. Lifetime of probes would likely be limited due to dulling of the probe tips.

Alignment marks can be obscured by cured polymer and metal fills applied to openings in the polymer. This solution presented herein enables the creation of new alignment marks in the cured polymer.

Crackstop features and/or moats created in the polymer can be filled by metals after polymer cure, thus the final passivation crackstop filled with copper (Cu) tends to corrode during transportation of the wafers between the fabricators and/or when subjected to thermal cycling during wafer finishing operations. This corroded Cu in the crackstop leads to alignment issues during the wafer test as well as dicing operations.

The novel solution includes the fabrication of an in-polymer redistribution wiring layer using an open/plate/damascene process. Any integration scheme that incorporates wiring within a polymer layer with a damascene process to remove a metal overburden from plating can benefit from the proposed process.

Further electrical diagnostics on the device may be prevented if needed electrical connective pads are blocked by a cured polymer. The novel method allows buried electrical pads on a device coated with a permanent passivation polymer to be selectively accessed using electrical testing probes.

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This novel method enables the creation of a moat or cra...