Low-Cost, High-Precision Method of Etching Semiconductors

Chip makers and semiconductor researchers need to precisely control the dimensions of their devices because they affect performance, speed, error rate, and time to failure. Semiconductors are commonly shaped by etching with chemicals but etching errors, such as residual layers, can affect the ability to further process and etch as well as hamper device performance. University of Illinois researchers have developed a low-cost method to carve delicate features onto semiconductor wafers using light. The new technique can monitor a semiconductor's surface as it is etched, in real time, with nanometer resolution. It uses a special type of microscope that uses two beams of light to very precisely measure topography. Because the new method is purely optical, there is no contact with the semiconductor surface and the researchers can monitor the whole wafer at once instead of point-by-point.

Transcript

00:00:12 there's growing need for tight dimensional control in the semiconductor manufacturing industry um so we developed a method that's capable of real-time monitoring of the height of semiconductor features as they're being etched um specifically we made a video where we can see the etching of gy maride uh in a wet etch solution we are actually able to sculpt the

00:00:34 three-dimensional nanoscale topography using a process known as photochemical etching we simply display the pattern that we want to etch on the sample using a computer projector image we use conventional photolithography to define the University of Illinois logo with silicon dioxide as a hard mask we place the sample into a water solution and then we drip acid the acid begins to

00:00:59 diffuse under the sample and begins to etch in the top left corner there is a diagonal line in the bottom left corner which is a scratch in the sample near the end of the video you can see that the etch depth is lower or not as deep in the regions that are narrow between the lines and especially near the curl of the eye with our method we can obtain such information about the

00:01:21 non-uniformities in the edge and be able to characterize them both over time and at all positions in space the instrumentation that we are developing will allow Engineers to thoroughly understand their fabrication processes and make adjustments to their conditions in real time we have begun to apply our methods to study the expansion and deformation of materials the rolling

00:01:47 of nanot tubes and the Dynamics of cell growth this work was sponsored by the National Science Foundation major research instrumentation program with matching funds from the University of Illinois