Browse Prior Art Database

Quartz Via Etch Process End Point Detection Control Software

IP.com Disclosure Number: IPCOM000088421D
Original Publication Date: 1977-Jun-01
Included in the Prior Art Database: 2005-Mar-04
Document File: 5 page(s) / 148K

Publishing Venue

IBM

Related People

Smith, EG: AUTHOR

Abstract

Shown below is control software to effect the end of etch for a first level quartz via etch process step. The process end-point detection (PEPD) algorithm presented hereunder enhances formation of (first metal to second metal contact) vias. Additionally, the Quartz Via Etch PEPD algorithm detailed below can be used for etching second and third quartz vias.

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Quartz Via Etch Process End Point Detection Control Software

Shown below is control software to effect the end of etch for a first level quartz via etch process step. The process end-point detection (PEPD) algorithm presented hereunder enhances formation of (first metal to second metal contact) vias. Additionally, the Quartz Via Etch PEPD algorithm detailed below can be used for etching second and third quartz vias.

In addition to signalling process end point time (t(E)), corresponding to a point of radical departure on the reflectivity waveform, the Quartz Via Etch PEPD algorithm supplies estimates of (1) quartz thickness removed and (2) quartz etch rate (which can vary during the quartz etch process). An alternate process shut- down scheme can be employed in place of that shown herein. Assume that (1) etch rate is modeled as

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R(t) = Square Root of a + bt + c, where a, b, and c denote least-squares fitting coefficients, or by R(t) = A + B exp Ct, where A, B, and C denote fitting coefficients based upon past values of etch rate, and assume that (2) maximum quartz peak height over vias (T(m)) is known. Using the latter mentioned etch rate model, the amount of planarized quartz removed from t = t(E) to t = t(E) + Delta t (Delta t denotes the over-etch time required to guarantee removal of quartz peaks) is calculated to be T(t+ Delta t) = ADelta t + (B/C) [exp C(t(E) + Delta t) - exp Ct(E)] from which Delta t can be found, say, by using the simple (and very efficient) Newton reiterative algorithm to minimi...