In recent years, Oxford Instruments Plasma Technology (OIPT) has received several requests to process multiple compound semiconductor wafers to help customer systems achieve increased throughput and reduced cost of ownership.
Consequently, the Applications Team has initiated an internal program to tackle this market, utilizing the PlasmaPro100 ICP180 and 380 systems at different batch sizes. It is necessary to have a substrate carrier to get the wafers into the chamber, so the company developed a substrate carrier from the carrier technology designed for use in the HBLED production.
Solution from OIPT
Good uniformity can be achieved across a batch of wafers if the plasma over the chosen etching area is homogenous. The selection of the appropriate plasma source to be used is based on the size of the batches and wafers requested by the customers. Recently, OIPT together with Fraunhofer Heinrich Hertz Institute (FhG HHI) has been working on a 3 x 3" batch size utilizing a PlasmaPro100 ICP380 to etch InP based devices by means of a CH4/H2 type chemistry, as shown in Figure 1.
Figure 1. Etching InP based devices by means of a CH4/H2 type chemistry (Courtesy of FhG HHI)
Typically, etching a single 3" wafer using this type of chemistry achieves a etch rate of 100 nm/min, with a profile of more than 80° and uniformity of ±2%. Together with FhG HHI, OIPT has devised a batch process over three 3" wafers. The new process delivers an etch rate of 100 nm/min, with a profile of more than 80° and uniformity of ±3% across the batch. The SEM images of profiles taken at the center and edge of the wafer/carrier are shown in Figures 2 and 3.
Figure 2. Center of Wafer (Courtesy of FhG HHI)
Figure 3. Edge of Wafer (Courtesy of FhG HHI)
The SEM images clearly demonstrate the outstanding process homogeneity and etch rate over a three wafer batch process utilizing the CH4/H2 type chemistry.
In the coming months, OIPT’s Applications Team will be working on various materials for etching, so as to further improve the yield of the batch process that can be achieved on Oxford Instruments systems.
This information has been sourced, reviewed and adapted from materials provided by Oxford Instruments Plasma Technology.
For more information on this source, please visit Oxford Instruments Plasma Technology.