ELEC7730. Reactive Ion Etching. Instructed by Dr. Tzeng Tan Zhang ECE--AU Feb. 28, 2001. Outline. Introduction RIE Apparatus and Reaction Steps Contamination and Damage Current Application and Trend Summary. Introduction. What is RIE?
RIE Apparatus and Reaction Steps
Contamination and Damage
Current Application and Trend
What is RIE?
RIE is plasma-based dry etching technique characterized by a combination of physical sputtering with the chemical activity of reactive species. It enables the anisotropy in the etching.
Plasma based dry etching processes are superior to wet etching because of the etching directionality, cleanliness, compatibility with automation and vacuum processing technologies.
(Up) Schematic diagram of apparatus used for RIE in semiconductor processing.
(Right) RIE system from Eidgenossische Technishe Hochschule Suiss Federal Institute of Technology
Since both the electrodes and the walls of the reactor can become sources of sputtered material which may deposit on the wafer being etched, the choice of the wall/electrode materials is of critical importance.The electrode effects can significantly alter the plasma chemistry.Micromasking and surface roughening can be avoided by using electrode materials which form volatile products with the etching gas.
Transport of plasma-generated reactive intermediates
Formation of a DC bias for ion acceleration
Active species generation
Desorption of volatile reaction product
Pumpout of volatile reaction product
Deep RIE process of Pyrex glass using SF6 plasma
Etch rates as a function of process,self-bias voltage -390 V, etching time 1 h).
SEM images (self-bias voltage -390 V, etching time 1 h).
Etch rates as a function of self-bias voltage and the SEM images, pressure 0.2 Pa, etching time 1 h.
SEM images: Etch rates as a function of self-bias voltage, pressure 0.2 Pa, etching time 1 h.
The schematic illustration of the scoop-out etching method
Honeycomb structure fabricated by the scoop-out etching method: (A) before etching; (B) after etching. The wafer thickness is 200 micrometer and the etching time is 10 h.
Micropump structure with SMA actuator: (a) pressurization type and (b) evacuation type.
After bonding the Pyrex glass cap to the TiNi thin film, the remaining Si layer beneath the TiNi thin film was removed by reactive ion etching (RIE) in SF6 gas. In this etching process, only the remaining Si layer has to be etched, without etching of the TiNi thin film. In order to achieve this, we need to measure the etch rates of Si and TiNi thin film, as well as those of SiO2, Cr and positive photoresist layers as a mask material.
(Up) Schematic diagram of the process flow steps to fabricate CVD diamond membrane.
(Right) SEM (a) backside of diamond membrane and (b) typical morphology of the backside of the fabricated diamond membrane using the RIE etching process
Schematic illustration of idea of one-chip multichannel QCM sensor
Process steps of the multichannel sensor
Representation of the parameter space in plasma etching. The key internal plasma properties (middle) are the bridge between externally controlled variables (top) and the figures of merit (bottom).