Patent Application
20150084057
This disclosure relates generally to methods and structures for reducing the propagation of cracks in epitaxial films for on semiconductor wafers and more particularly to methods for reducing the propagation of cracks in epitaxial films having a different crystallographic structure than the crystallographic structure of the semiconductor wafer.
As is known in the art, Group III-N epitaxial film growth on Si substrates tend to have high stress developed in the films, leading to crack formation at the edge of the epitaxial layers that may propagate further into interior regions of the epitaxial layer as a result of subsequent processing. During fabrication, the wafers with the epitaxial layers are exposed to subsequent mechanical stress, such as electrostatic chucks, backside vacuum, and robotic vacuum handling, and thermal stresses, such as during thin film deposition and anneal, which can cause the cracks in the edges of the epitaxial film to propagate and degrade the epitaxial film and/or cause wafer breakage.
In accordance with the present disclosure, a method is provided comprising: providing a semiconductor wafer with an epitaxial film thereon; inspecting the epitaxial film to determine outer peripheral edge regions of the epitaxial film having cracks therein; and selectively removing the determined outer peripheral edge regions of the epitaxial film while leaving portions of the semiconductor wafer underlying the removed determined outer peripheral regions of the epitaxial film.
In one embodiment, the epitaxial film has a different crystallographic structure than the crystallographic structure of the semiconductor wafer.
In one embodiment, the wafer is silicon and the epitaxial film is a compound of nitrogen.
In one embodiment, the wafer is silicon and the epitaxial film is a Group III-N material.
In one embodiment, the wafer is silicon and the epitaxial film is a Gallium Nitride.
In one embodiment, the silicon is <111> silicon.
In one embodiment a method is provided comprising: providing a semiconductor wafer with an epitaxial film thereon, the epitaxial film having outer peripheral regions with cracks therein; and selectively removing peripheral regions of the epitaxial film while leaving portions of the semiconductor wafer underlying the removed determined outer peripheral regions of the epitaxial film.
In one embodiment, a semiconductor structure is provided, comprising: a semiconductor wafer, the wafer having an outer peripheral edge; and an epitaxial film disposed on and in direct contact with a central portion of the semiconductor wafer and being displaced a predetermined distance from the peripheral edge of the wafer.
With such method, the cracked edges of III-N epitaxial films are removed from the Si substrates. As a result, the edge cracks are eliminated and no longer propagate through the epitaxial film during subsequent processing.
The details of one or more embodiments of the disclosure are set forth in the accompanying drawings and the description below. Other features, objects, and advantages of the disclosure will be apparent from the description and drawings, and from the claims.
Like reference symbols in the various drawings indicate like elements.
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A number of embodiments of the disclosure have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the disclosure. Accordingly, other embodiments are within the scope of the following claims.
