Method of etching substrates

#1. Field of the Invention

#This invention relates to semiconductor fabrication. More specifically, the present invention relates to the use of reactive ion etching in semiconductor fabrication.

#2. Discussion of the Related Art

#The accompanying figures, in which like reference numerals refer to identical or functionally-similar elements throughout the separate views and which are incorporated in and form part of the specification, further illustrate the present invention and, together with the detailed description of the invention, serve to explain the principles of the present invention.

#FIG. 1 illustrates a substrate having multiple individual semiconductor devices.

#FIG. 2 illustrates the substrate of FIG. 1 after being thinned.

#The following generally describes a process for dicing substrates to separate individual semiconductor devices and a process for thinning substrates. The described processes are particularly advantageous when dicing and thinning hard substrates such as sapphires and SiC. Other substrates that can be used include Si, GaAs, InP, ZnSe, ZnO, and GaP. All semiconductor devices fabricated on a hard semiconductor substrate can be separated with ICP RIE scribing method. Furthermore, some metals can be etched using the described process. However, it should be understood that following describes only some of the many different embodiments that are in accord with the principles of the present invention. Therefore, the present invention is to be understood as encompassing all of the embodiments covered by the claims that follow and by their equivalents.

#The principles of the present invention make use of inductively coupled plasma reactive ion etching (ICP RIE) to separate individual semiconductor devices that were previously formed on a substrate. As a motivation for the present invention was separating GaN-based devices that were fabricated on sapphire, the illustrated embodiments are directed to dicing and thinning sapphire substrates. However, other materials can be similarly processed. Thus, a general process for dicing individual elements formed on a sapphire substrate will be described first, followed by more details about the ICP RIE process, in turn followed by a discussion of ICP RIE in substrate thinning and polishing.

#FIG. 1 illustrates a sapphire substrate 12 having multiple individual semiconductor devices 14. For example, the semiconductor devices might be GaN-based LEDs that are fabricated by depositing and processing epitaxial layers on the sapphire substrate 12. Such GaN-based LED devices could consist of multiple epitaxial layers of un-doped GaN, n-type GaN doped with Si, multiple quantum wells having InGaN/GaN layers, p-type AlGaN doped with Mg, and p-type GaN doped with Mg. Of course, other types of semiconductor devices, such as laser diodes and/or electronic devices, could be formed on the sapphire substrate 12.