BACKGROUND

A. Technical Field

The present invention relates to semiconductor wafers, and more particularly, to wafers having a diamond layer and a semiconductor layer including III-nitride semiconductor material and methods for fabricating the wafers and devices.

B. Background of the Invention

Gallium Nitride (GaN) or AlGaN or AlN has electrical and physical properties that make it highly suitable for radio frequency (RF) devices, such as high electron mobile transistors (HEMTs). In general, an RF device produces a large amount of heat energy during operation, requiring a mechanism to extract the heat energy from the device to avoid device failure. Diamond is known to have a good thermal conductivity and can be used as material for a substrate on which the AlGaN/GaN layer is formed.

One conventional approach to form an AlGaN/GaN HEMT layer on a diamond layer is depositing AlGaN/GaN HEMT layer directly on a silicon substrate, removing the silicon substrate and forming a diamond layer on the AlGaN/GaN HEMT layer. This approach is attractive for its low manufacturing cost. However, the conventional technique is not suitable for manufacturing AlGaN/GaN HEMT in a consistent manner. First, the thickness of the wafers is much less than 200 μm, where a typical semiconductor processing equipment has robot arms for carrying semiconductor wafers and the robot arms require that the thickness of each wafer be at least 500 μm. Second, as the conventional wafers are too thin, the wafers may not have sufficient mechanical strength to withstand the thermal and mechanical stresses during the subsequent processes for forming semiconductor devices in wafers. Thus, there is a need for a new technique for providing mechanical strength for the wafers and to meet the requirement for the robot arms used in the semiconductor processing.

SUMMARY OF THE DISCLOSURE

According to one aspect of the present invention, a method for fabricating a semiconductor wafer includes: disposing a nucleation layer on a substrate; disposing at least one semiconductor layer on the nucleation layer, the at least one semiconductor layer including a III-Nitride compound; disposing a protection layer on the at least one semiconductor layer; bonding a carrier wafer to the protection layer, the carrier wafer including a SiC substrate; removing the substrate, the nucleation layer and a portion of the at least one semiconductor layer; disposing a diamond layer on the at least one semiconductor layer; depositing a substrate wafer on the diamond layer; and removing the carrier wafer and the protection layer.

