BACKGROUND

Embodiments of the present disclosure generally relate to a showerhead for processing chambers, and, more particularly, to a showerhead having a high aspect ratio of holes and a high hole density for processing chambers.

Description of the Related Art

In many conventional showerhead designs, the showerhead includes a gas distribution plate having a plurality of holes through which a processing gas may flow. However, the number of holes and the aspect ratio of those holes may be limited. Hence, the uniformity of the flow of the processing gas through the showerhead is limited. A major factor in limiting the number of holes within a gas distribution plate is the process in which the holes are generated. For example, mechanical drilling of holes may place high levels of stress on the gas distribution plate potentially damaging the gas distribution plate and/or may create burrs within the gas distribution plate. Further, mechanical drilling is time prohibitive and may be process limited. For example, in many instances, mechanical drilling utilizes a spindle coolant fed drills, which are available in the smallest diameter size of about 500 um, limiting the smallest possible hole that may be drilled. Other subtractive drilling methods include ultrasonic drilling or micro electrical discharge machining (EDM), which are both time prohibitive. A further example of subtractive drilling includes laser drilling which is typically limited to about a 10:1 aspect ratio and which is also time prohibitive. Accordingly, the conventional methods of generating holes limit the size of the holes and the aspect ratio of the holes, while increasing the manufacturing cost of the gas distribution plate. Further, the conventional methods of holes generation limit the hole density, which limits the uniformity of a process gas flowing through the gas distribution plate.

Therefore, in order to improve the uniformity of gas distribution, there is a need for improved fabrication methods to create a large number of small diameter holes in a gas distribution plate in a cost-effective way.

SUMMARY

In one embodiment, a gas distribution plate for a showerhead assembly includes a first plate and second plate. The first plate may comprise a first plurality holes each having a diameter of at least about 100 um. The second plate may comprise a second plurality of holes each having a diameter of at least about 100 um. Further, each of the first plurality of holes is aligned with a respective one of the second plurality of holes forming a plurality of interconnected holes. Each of the plurality of interconnected holes is isolated from each other of the plurality of interconnected holes.

In one embodiment, a method for forming a showerhead comprises generating a first plurality of holes in a first plate and generating a second plurality of holes in a second plate. Each of the first plurality of holes has a diameter of at least about 100 um and each of the second plurality of holes has a diameter of about 100 um. The method further comprises aligning each of the first plurality of holes with a respective one of the second plurality of holes to generate a plurality of interconnected holes, and bonding the first plate to the second plate. Each of the plurality of interconnected holes is isolated from each other of the plurality of interconnected holes.

In one embodiment, a processing chamber comprises a showerhead assembly, a substrate support configured to support a substrate and a gas supply fluidly coupled with the showerhead assembly and configured to provide a process gas to the showerhead assembly. The showerhead assembly comprises a gas distribution plate including a first plate and second plate. The first plate comprises a first plurality holes each having a diameter of at least about 100 um. The second plate comprises a second plurality of holes each having a diameter of at least about 100 um. Further, each of the first plurality of holes is aligned with a respective one of the second plurality of holes forming a plurality of interconnected holes, and each of the plurality of interconnected holes is isolated from each other of the plurality of interconnected holes.

