A Mathematical Model for a Parallel Plate Plasma Etching Reactor

Economou, Demetre J.; Alkire, Richard C.

doi:10.1149/1.2095434

Cited by 38 publications

(35 citation statements)

References 17 publications

(28 reference statements)

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“…[1][2][3][4][5][6][7][8][9][10][11][12] More detailed uniformity studies are needed, however, because industry requirements for Al etch uniformity are becoming more stringent. [1][2][3][4][5][6][7][8][9][10][11][12] More detailed uniformity studies are needed, however, because industry requirements for Al etch uniformity are becoming more stringent.…”

Section: Introductionmentioning

confidence: 99%

Trends in aluminum etch rate uniformity in a commercial inductively coupled plasma etch system

Beale

Siu

Patrick

1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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Characterization of an aluminum etching process in an inductively coupled discharge using measurements of discharge impedance and current and voltage sensors The effects of process conditions and chamber geometry on the uniformity of Al etched by Cl 2 were measured in a Lam TCP™ 9600 SE etch reactor. A computer simulation accurately predicted etch uniformity and aided in the explanation of uniformity trends. Parameters used in the experimental matrix included pressures between 6 and 24 mT, flow between 25 and 100 sccm, power supplied to the plasma between 0 and 350 W, and chamber heights ranging from 6 to 12 cm. The distinctive features of this study include the large number of input parameters studied in a commercial reactor and the accurate predictions obtained from a self-consistent simulation without free parameters. Reducing residence time in the experiments by adjusting chamber height or flow rate produces a more center-fast etch, as expected. The flow simulations were useful in corroborating intuitive arguments and in explaining anomalous results such as the effect of pressure on etch uniformity. More specifically, comparison of simulations and measurements demonstrated the quantitative connection between the Peclet number, the residence time, and the edge uniformity over a large range of process conditions. In addition to explaining general trends with residence time, Peclet number considerations also clarify the differing effects of pressure, flow rate, and chamber height change on uniformity. No attempt was made to impose plasma effects in the flow simulation because measurements of the neutral temperature and dissociation fraction were not available. Plasma power was observed experimentally to slightly improve uniformity without changing the average etch rate.

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Section: Introductionmentioning

confidence: 99%

Trends in aluminum etch rate uniformity in a commercial inductively coupled plasma etch system

Beale

Siu

Patrick

1998

Journal of Vacuum Science &Amp; Technology B: Microelectronics and Nanometer Structures Processing, Measurement, and Phenomena

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“…8 together with the experimentally measured etching rate under various SF6 flow rates. [7] ~p=-L2kine [14] Dj The Thiele modulus can be physically interpreted as the ratio between the rate of gas phase electron bombardment dissociation and the rate of diffusion. The minima move forward to the direction of gas entrance as the flow rate of SF6 is increased.…”

Section: Resultsmentioning

confidence: 99%

“…The electrical properties used in this model are obtained from impedance measurements and by comparison to other investigations (4,5,7). The mathematical model can be used to predict reactor behavior for achieving a desired etch rate and uniformity.…”

Section: Discussionmentioning

confidence: 99%

Plasma Etching of Silicon in SF 6 : Experimental and Reactor Modeling Studies

Lii

Jorné

Cadien

et al. 1990

J. Electrochem. Soc.

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A theoretical model is developed for plasma etching of silicon with SF6. The three-dimensional model developed includes diffusion and convection of molecular fragments in a duct geometry. Active species generation is described by electron impact dissociation reactions which are functions of the electric field and gas density. Dissociative chemisorption is also considered as a source of fluorine atom generation. Fundamental plasma parameters such as electron density and electric field are estimated from impedance measurements in a designed experiment. Good agreement is obtained between model predictions of silicon etching rate and experimental results obtained under various ranges of flow rate, pressure, power, and electrode gap.

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“…Both of these effects lead to a reduction in total chlorine flux arriving at the wafer surface. Economou et al 78 develop a model for a parallel plate reactor which demonstrates how reactant concentration can be reduced over a wafer at high values for the Thiele modulus, which describes the effect of chemical etching as compared to diffusion. We have added a reaction at the wafer surface which allows incident Cl 2 and Cl to stick and form etch product with a probability of 0.48 and 0.6, respectively.…”

Section: In a Lammentioning

confidence: 99%

Semiempirical profile simulation of aluminum etching in a Cl2/BCl3 plasma

Cooperberg

Vahedi

Gottscho

2002

Journal of Vacuum Science &Amp; Technology A: Vacuum, Surfaces, and Films

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Articles you may be interested inModel for photoresist trim etch in inductively coupled CF 4 / O 2 plasma Effect of Ar addition to an O 2 plasma in an inductively coupled, traveling wave driven, large area plasma source: O 2 /Ar mixture plasma modeling and photoresist etching J. Appl. Phys. 90, 3205 (2001); 10.1063/1.1398600Modeling and simulation of feature-size-dependent etching of metal stacks A semiempirical profile simulator to predict topographic evolution during Cl 2 /BCl 3 plasma etching of photoresist patterned Al lines has been developed. Given incident flux distributions, the profile simulator uses a combination of a particle based Monte Carlo algorithm and analytic ray-tracing algorithm for solving feature-scale ion and neutral flux transport, respectively. We use angular and energy distributions for reflected ions that are consistent with experimental observation and molecular dynamic simulations. Etch yields with energy and angular dependence are experimentally determined for physical sputtering and ion-enhanced etching. The spontaneous etch rate of A1 by chlorine and the spontaneous desorption rate of Cl from photoresist are estimated from experimental results. Sticking coefficients for etchant, chlorine, and depositor, CCl x , and depositing flux are determined by fitting simulated profiles to experimental data. A semiempirical site-balance model is developed to compute the surface coverage of etchant. The reaction probability of neutrals at surfaces is self-consistently determined from the surface coverage at incident location. Competition between etching and deposition on feature sidewalls is modeled. A shock-tracking method is used to advance the profile using computed etch/deposition rates. Simulation results are presented which demonstrate that facet formation, aspect ratio dependent etching, and critical dimension gain, are captured accurately by the calibrated profile simulator. In addition, the calibrated profile simulator along with results of a 2 3 design of experiments in which photoresist and Al etch rates were measured on open frame wafers have been used to create a plasma reactor model. The reactor model relates the operational parameters including inductively coupled power, rf bias and gas flow ratio to the flux variables, i.e., Cl flux, ion flux, ion energy, and depositor flux, that are used as inputs to the profile simulator. In this manner, calibration of the profile simulator requires a minimum of high resolution, expensive, patterned wafers. The reactor model so created is shown to be in quantitative agreement with results from the hybrid plasma equipment model ͑Ref. 1͒.

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A Mathematical Model for a Parallel Plate Plasma Etching Reactor

Cited by 38 publications

References 17 publications

Trends in aluminum etch rate uniformity in a commercial inductively coupled plasma etch system

Trends in aluminum etch rate uniformity in a commercial inductively coupled plasma etch system

Plasma Etching of Silicon in SF 6 : Experimental and Reactor Modeling Studies

Semiempirical profile simulation of aluminum etching in a Cl2/BCl3 plasma

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