Recursive least squares estimation for run-to-run control with metrology delay and its application to STI etch process

Author

Wang, Jin ; He, Q. Peter ; Qin, S.Joe ; Bode, Christopher A. ; Purdy, Matthew A.

Author_Institution

Adv. Micro Devices Inc., Austin, TX, USA

Volume

18

Issue

2

fYear

2005

fDate

5/1/2005 12:00:00 AM

Firstpage

309

Lastpage

319

Abstract

Run-to-run (RtR) control technology has received tremendous interest in semiconductor manufacturing. Exponentially weighted moving average (EWMA), double-EWMA, and internal model control (IMC) filters are recognized methods for online RtR estimation. In this paper, we consider recursive least squares (RLS) as an alternative for online estimation and RtR control. The relationship between EWMA-type and RLS-type estimates is analyzed and verified with simulations. Because measurement delay is almost inevitable in semiconductor manufacturing, we discuss and compare the performance of EWMA, RtR-IMC, and RLS controllers in handling measurement delay and measurement noise for processes with a deterministic drift. An ad hoc solution is proposed to handle measurement delay for processes with time-varying drifts. The results are illustrated through several simulations and a shallow trench isolation (STI) etch process as an industrial example.

Keywords

delays; etching; least squares approximations; manufacturing processes; moving average processes; process control; STI etch process; ad hoc solution; deterministic drift; double-EWMA; exponentially weighted moving average; internal model control; measurement delay; measurement noise; online RtR estimation; recursive least squares estimation; run-to-run control; semiconductor manufacturing; shallow trench isolation; time-varying drifts; Delay estimation; Etching; Filters; Least squares approximation; Metrology; Noise measurement; Process control; Recursive estimation; Resonance light scattering; Semiconductor device manufacture; Double exponentially weighted moving average (EWMA); EWMA; internal model control (IMC); measurement delay; recursive least squares (RLS); run-to-run (RtR) control; shallow trench isolation (STI);

fLanguage

English

Journal_Title

Semiconductor Manufacturing, IEEE Transactions on

Publisher

ieee

ISSN

0894-6507

Type

jour

DOI

10.1109/TSM.2005.846819

Filename

1427800