Endpoint detection method for time division multiplex etch processes

Russ Westerman; Dave Johnson; Shouliang Lai; Mike Teixeira

doi:10.1117/12.646498

23 January 2006 Endpoint detection methods for time division multiplex etch processes

Russ Westerman, Dave Johnson, Shouliang Lai, Mike Teixeira

Proceedings Volume 6109, Micromachining and Microfabrication Process Technology XI; 61090I (2006) https://doi.org/10.1117/12.646498
Event: MOEMS-MEMS 2006 Micro and Nanofabrication, 2006, San Jose, California, United States

Abstract

During the fabrication of many MEMs devices it is required to etch a layer of material to completion stopping on the layer below (e.g. Silicon on Insulator (SOI) - clearing a Si layer stopping on an underlying silicon dioxide layer). Allowing the etch process to proceed beyond the time when the first layer has been removed can result in reduced thickness of the underlying stop layer, or feature profile degradation (known as "notching" for SOI applications). One method commonly used to detect plasma process termination times is optical emission spectrometry (OES). OES analyzes the light emitted from a plasma source to draw inferences about the chemical and physical state of the plasma process. In semiconductor processing this technique is commonly used to detect material interfaces during plasma etch processes. While this approach works well for single step processes or process with a limited number of discrete etch steps (such as an etch initiation followed by a main etch) it is difficult to apply OES techniques to plasma processes with rapid and periodic plasma perturbations such as time division multiplex (TDM) plasma etching processes for Si etching. At Unaxis USA, we have developed a proprietary optical emission end point algorithm in conjunction with OES to detect material transitions in TDM processes. This technique requires no synchronization of the algorithm to the TDM process and has been applied to silicon on insulator (SOI) structures. The mechanism and performance of the algorithm will be discussed. The sensitivity of the technique has been evaluated over a range of silicon etch loads. Signal to Noise (SNR) ratios of greater than 15:1 have been achieved for samples with less than 10% exposed silicon.

Citation Download Citation

Russ Westerman, Dave Johnson, Shouliang Lai, and Mike Teixeira "Endpoint detection methods for time division multiplex etch processes", Proc. SPIE 6109, Micromachining and Microfabrication Process Technology XI, 61090I (23 January 2006); https://doi.org/10.1117/12.646498

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available