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Silicon Trench Formation Using Alternating Reactive Ion Etch And Oxidation

IP.com Disclosure Number: IPCOM000101277D
Original Publication Date: 1990-Jul-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 1 page(s) / 31K

Publishing Venue

IBM

Related People

Callan, CA: AUTHOR [+3]

Abstract

By alternating reactive ion etching (RIE) using a chlorine (Cl2) and oxygen (O2) gas blend followed by plasma oxidation, highly anisotropic etching of silicon (Si) at a rate of more than 500 nm/min is achieved. An etch rate ratio (ERR) of Si to silicon dioxide (SiO2) masking material is higher than 50:1 with this process.

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Silicon Trench Formation Using Alternating Reactive Ion Etch And Oxidation

       By alternating reactive ion etching (RIE) using a
chlorine (Cl2) and oxygen (O2) gas blend followed by plasma
oxidation, highly anisotropic etching of silicon (Si) at a rate of
more than 500 nm/min is achieved.  An etch rate ratio (ERR) of Si to
silicon dioxide (SiO2) masking material is higher than 50:1 with this
process.

      RIE of Si using etch gas mixtures of Cl2 and O2 attacks the Si
at a high rate but has a high degree of isotropic etching, thus
undercutting an etch mask.  By alternating RIE using Cl2/O2 gas
mixtures with plasma oxidation several times during a process to cut
features, e.g., trenches, the high etch rate and ERR for Si over SiO2
is retained while eliminating sidewall attack.  Thus, vertical
sidewalls may be achieved in features formed in Si.  However, varying
time duration of etching steps relative to time duration of oxidation
steps can be used to vary degree of anisotropy of etching.

      The change from RIE to plasma treatment is achieved simply by
cutting off Cl2 flow and adjusting O2 flow rate to achieve constant
system pressure.  Programming several changes from etching to
oxidation and back is quite simply done in commercially available
equipment.