Publicações / Publications


Full Texts:

  1. M.B. Pisani. Medidas elétricas de RF em reatores de processamento a plasma. [RF electrical measurements in plasma processing reactors]. São Paulo. 2001. 128p. Dissertation (Master of Science) – Escola Politécnica da Universidade de São Paulo – Departamento de Engenharia Elétrica [Polytechnic Scholl of the University of São Paulo - Electrical Engineering Department]. [  Abstract  ] [  Resumo ]

  2.  
  3. M.B. Pisani, P. Verdonck. RF electrical measurements in plasma processing reactors. In: INTERNATIONAL CONFERENCE ON MICROELECTRONICS AND PACKAGING, 15., Manaus (AM, Brazil), Sept. 2000. Proceedings. São Paulo, Sociedade Brasileira de Microeletrônica [Brazilian Microelectronics Society], 2000. p.348-351. [ Abstract ]

  4.  
  5. R.M. de Castro, P. Verdonck, M.B. Pisani, R.D. Mansano, G.A. Cirino, H.S. Maciel, M. Massi. End-point detection of polymer etching using Langmuir probes. IEEE Transactions on Plasma Science, v.28, n.3, p.1043-49, June 2000. [  Abstract ]

  6.  
  7. M. Massi, R.D. Mansano, P. Verdonck, H.S. Maciel, G.A. Cirino, R.M. de Castro, M.B. Pisani. Performance characterisation of an RIE reactor with built-in excitation antenna. Journal of Solid-State Devices and Circuits, v.8, n.1, p.1, February 2000. [  Abstract  ]

  8.  
  9. R.M. de Castro, P. Verdonck, M.B. Pisani, R.D. Mansano, G.A. Cirino, H.S. Maciel, M. Massi. The applicability of Langmuir probes for end point detection of polymer etching. In INTERNATIONAL CONFERENCE ON MICROELECTRONICS AND PACKAGING, 14., Campinas (SP, Brazil), Aug. 1999. Proceedings. São Paulo, Sociedade Brasileira de Microeletrônica [Brazilian Microelectronics Society], 1999. p.24-8. [  Abstract  ]

  10.  
  11. R.M. de Castro, G.A. Cirino, P. Verdonck, H.S. Maciel, M. Massi, M.B. Pisani, R.D. Mansano. A comparative study of single and double Langmuir probe techniques for RF plasma characterization. Contributions to Plasma Physics, v.39, n.3, p.235-246, 1999. [  Abstract  ]

  12.  
  13. R.M. de Castro, G.A. Cirino, P. Verdonck, H.S. Maciel, M. Massi, M.B. Pisani, R.D. Mansano. Comparison between single and double Langmuir probe techniques for analysis of inductively coupled plasmas. In INTERNATIONAL CONFERENCE ON MICROELECTRONICS AND PACKAGING, 13. Proceedings. Curitiba (PR, Brasil), Sociedade Brasileira de Microeletrônica [Brazilian Microelectronics Society], 1998. v.1 - p.508-14. /also published in Boletim Técnico da Escola Politécnica da USP [Technical Report of the Polytechnical School of the University of São Paulo], n. BT/PEE/9824, n.p., 1998./ [  Abstract  ]

Tecnical Comunications, Oral Presentations, Pannels:

  1. M.B. Pisani, P. Verdonck. RF electrical measurements in argon and SF6 discharges. In ENCONTRO BRASILEIRO DE FÍSICA DE PLASMAS – EBFP, 6., Campos do Jordão (SP, Brazil), Dec. 2001. [6th Brazilian Plasma Physics Meeting]. Abstracts. São Paulo, Sociedade Brasileira de Física [Brazilian Physical Society], s.d., n.p. (submited, not accepted/published yet). [ Abstract ]

  2.  
  3. M.B. Pisani, R.M. de Castro, G.A. Cirino, P. Verdonck. Single, double and floating Langmuir probe measurement system for RF discharge studies. In ENCONTRO BRASILEIRO DE FÍSICA DE PLASMAS – EBFP, 6., Campos do Jordão (SP, Brazil), Dec. 2001. [6th Brazilian Plasma Physics Meeting]. Abstracts. São Paulo, Sociedade Brasileira de Física [Brazilian Physical Society], s.d., n.p. (submited, not accepted/published yet). [ Abstract  ]

  4.  
  5. M.B. Pisani, P. Verdonck. Development of an RF electrical measurement system for a plasma etching tool. In WORKSHOP DO SISTEMA BRASILEIRO DE TECNOLOGIA DE INFORMAÇÃO (SIBRATI), 4., São Paulo, Mar. 2001. [4th Brazilian Information Technology System Workshop]. Abstracts. São Paulo, Escola Politécnica da USP, 2001, n.p. (http://www.lsi.usp.br/~dmi/workshop2001)

  6.  
  7. M.B. Pisani, P. Verdonck. Utilização de plasmas indutivos para corrosão de silício. [Using inductive plasmas for silicon etching]. In CONGRESSO BRASILEIRO DE APLICAÇÕES DE VÁCUO NA INDÚSTRIA E NA CIÊNCIA, 20. São Paulo, Jul. 1999. [20th Brazilian Congress of Vaccum Applications on Industry and Science]. Abstracts. Campinas, Sociedade Brasileira de Vácuo [Brazilian Vacuum Society], 1999, p.65 (ref. 068). [ Resumo ]

  8.  
  9. M.B. Pisani, R.D. Mansano, P. Verdonck. Aplicação de plasmas de baixa freqüência em processos de corrosão de silício e fotorresiste. [Application of low-frequency plasmas in silicon and photoresist etching]. In CONGRESSO BRASILEIRO DE APLICAÇÕES DE VÁCUO NA INDÚSTRIA E NA CIÊNCIA, 18., Petrópolis (RJ, Brazil), Jul. 1997. [18th Brazilian Congress of Vaccum Applications on Industry and Science]. Abstracts. Campinas, Sociedade Brasileira de Vácuo [Brazilian Vacuum Society], 1997. n.p. (ref. 051) [ Resumo ]

  10.  
  11. M. Massi, R.D. Mansano, P. Verdonck, H.S. Maciel, M.B. Pisani, G.A. Cirino. Performance characterisation of an RIE reactor with a built-in RF excitation coil. In NATIONAL SYMPOSIUM OF THE AMERICAN VACUUM SOCIETY, 44., San Jose (CA, USA), Oct. 1997. Abstracts. San Jose, American Vacuum Society, 1997, p.46. [Abstract ]

  12.  
  13. M.B. Pisani, R.D. Mansano, P. Verdonck. Projeto e caracterização de um gerador de baixas freqüências aplicado à corrosão por plasma. [Design and characterization of a low-frequency generator applied to plasma etching]. In CONGRESSO BRASILEIRO DE APLICAÇÕES DE VÁCUO NA INDÚSTRIA E NA CIÊNCIA, 16. Brasília (DF, Brasil), Jul. 1995. [16th Brazilian Congress of Vaccum Applications on Industry and Science]. Abstracts. Campinas, Sociedade Brasileira de Vácuo [Brazilian Vacuum Society], 1995, n.p. (ref. 064) [  Resumo  ]

  14.  
  15. R.M. Franzin, P. Verdonck, R.D. Mansano. N. Ordonez, M.B. Pisani. Projeto e construção de um equipamento de corrosão de alumínio por plasma. [Design and construction of an aluminum plasma etching equipment]. In CONGRESSO BRASILEIRO DE APLICAÇÕES DE VÁCUO NA INDÚSTRIA E NA CIÊNCIA, 13., Campinas, Jul. 1992. [13th Brazilian Congress of Vaccum Applications on Industry and Science]. Abstracts. Campinas, Sociedade Brasileira de Vácuo [Brazilian Vacuum Society], 1992, n.p. (referência 060) [ Resumo ]


 

1. Full Texts Abstracts


Dissertação de Mestrado

MEDIDAS ELÉTRICAS DE RF EM REATORES DE PROCESSAMENTO A PLASMA

Marcelo B. Pisani, Patrick Verdonck (orientador)

Resumo

Este trabalho mostra a construção de um sistema de medidas elétricas de RF aplicado à caracterização elétrica de reatores de processamento a plasma trabalhando em 13,56 MHz. O sistema é baseado em duas pontas sensoras de tensão e de corrente conectadas o mais próximo possível ao eletrodo de processo para se evitar efeitos indesejados devido a capacitâncias e indutâncias parasitárias.

As formas de onda de tensão e de corrente são digitalizadas por um osciloscópio e tratadas por um programa de computador. Foi desenvolvido um esquema de calibração realizado em três etapas: utilizando referências de fase, referências de amplitude e um método baseado em impedâncias complexas de valores bem conhecidos para o cálculo de uma matriz de transferência ABCD para a rede de impedâncias parasitárias que compõem o sistema de medidas.

O sistema calibrado foi utilizado na medida de propriedades elétricas de plasmas num reator tipo RIE de lâmina única, utilizando como gases de processo argônio e hexafluoreto de enxofre, trabalhando em pressões entre 3 e 27 Pa e potências de RF entre 10 e 100 W. Foi proposto um modelo para a correção das medidas em função dos parâmetros parasitários do eletrodo de plasma, cujo elemento principal é a capacitância entre eletrodos, em torno de 100 pF. As resistências de plasma observadas ficaram entre 50 ohms e 1 quiloohm para hexafluoreto de enxofre e entre 50 e 300 ohms para argônio. As capacitâncias de bainha ficaram entre 20 e 200 pF para hexafluoreto de enxofre e entre 15 e 50 pF para argônio. O ângulo de fase da impedância ficou entre -87 e -60 graus para todas as medidas. Mostrou-se que ângulos acima da faixa de 70 a 80 graus em módulo tornam muito alta a incerteza no cálculo da potência de plasma.

[  Back ]    [  Main  ]


Master of Science Dissertation

RF ELECTRICAL MEASUREMENTS IN PLASMA PROCESSING REACTORS

Marcelo B. Pisani, Patrick Verdonck (advisor)

Abstract

This work shows the construction of an RF electrical measurement system applied to the electrical characterization of plasma processing reactors working at 13.56 MHz. The system is based on two probes, one for sensing voltage and another for current which are placed as close as possible to the process electrode to avoid parasitic circuit effects.

Voltage and current waveforms are digitized by an oscilloscope and processed by a computer program. The measurement system must be calibrated in order to provide significant results. A three step calibration procedure was established. A first step takes into account the phase (delay) between measured current and measured voltage. The second step calibrates the moduli of the measured current and voltage. The third step generates a transfer matrix which takes into account the reactive parasitic elements of the system.

The calibrated system was used for measuring electrical properties of a single wafer RIE reactor, using argon and sulfur hexafluoride as gases. The pressure was varied from 3 to 27 Pa, with power levels from 10 to 100 W. We proposed a model to correct the measurements for the plasma electrode parasitics, whose most important value is the inter-electrode capacitance, of about 100 pF. The plasma bulk resistance values observed were in the 50 ohm – 1 kiloohm range for sulfur hexafluoride and in the 50 – 300 ohm range for argon. The sheath capacitances are in the range of 20 – 200 pF for sulfur hexafluoride and between 15 and 50 pF for argon. The impedance phase angle is between -87 and -60 degrees for all the measures. We showed that angles higher than 70 – 80 degrees in modulus induce an exaggerated uncertainty in the power calculation.

[  Back ]    [  Main  ]




15th ICMP, Sept. 2000, p.348-351

RF ELECTRICAL MEASUREMENTS IN PLASMA PROCESSING REACTORS

Marcelo B. Pisani and Patrick Verdonck

Abstract

An integrated hardware-software tool was developed to determine accurately the applied voltage, current and phase angle near the powered electrode of a RIE plasma etching reactor.  This allows to evaluate the non-linearity of the plasma impedance and to characterise the harmonic distortions in the electrical signals. This work allows the use of RF electrical measurements as a method for improving control, reproducibility and correct characterisation of plasma processing reactors.

[  Back ]    [  Main  ]


IEEE Transactions on Plasma Science, v.28, n.3, p.1043-9, Jun. 2000.

END-POINT DETECTION OF POLYMER ETCHING USING LANGMUIR PROBES

Raul M. de Castro, Patrick Verdonck, Marcelo B. Pisani, Ronaldo Dominges Mansano, Giuseppe Antonio Cirino, Homero Santiago Maciel and Marcos Massi.

Abstract

The adequate determination of the end-point of a plasma-etching process is very important for integrated circuit fabrication. In this paper, the authors propose a new method, making use of the floating potential, as determined by a single Langmuir probe with a radio frequency (RF) choke. For the etching of polymer film with an oxygen plasma using a reactive ion-etching system, this method yields a reproducible and reliable signal, which was successfully used to detect the end-point for several wafers. It is better than the method using the dc self-bias voltage as the end-point detection signal, and approximately as good as when using emission spectrometry – at least when the resist area is larger than 4.4 cm2 – whereas it uses a much cheaper equipment set. Langmuir probe measurements indicate that the floating potential changes are caused by several mechanisms: the temperature, and the electron energy distribution all change after the end-point of the etching.

Index terms – Dissociation, ionization, plasma etching, plasma measurements, reactive plasmas.

[  Back ]    [  Main  ]



Journal of Solid-State Devices and Circuits, v.8, n.1, Feb. 2000.

PERFORMANCE CHARACTERIZATION OF AN RIE REACTOR WITH BUILT-IN RF EXCITATION ANTENNA.

Marcos Massi, Ronaldo D. Mansano, Patrick Verdonck, Homero S. Maciel *, Giuseppe A. Cirino, Raul M. de Castro, Marcelo B. Pisani.
LSI/PSI/EPUSP, * Departamento de Física – ITA.

Abstract

A conventional Reactive Ion Etching system was modified into an Inductively Coupled Plasma-like reactor by inserting a metal antenna into the reactor. In this way, RF power can be applied independently to this antenna an to the lower electrode.

Applying RF power to the antenna causes de floating and plasma potentials to increase and, as a consequence, the DC self-bias voltage also becomes more positive. The plasma density increases by up to a factor of 3, when 100 W is applied to the antenna.

Monocrystalline silicon was etched with SF6-based plasmas in the 10 to 25 mTorr pressure range. When applying RF power to the antenna, the etch rate increases by 10% to 30%, with the highest increase at lower pressure levels. At the same time, the anisotropy of the etching increases, probably because of an increased polymerization. In addition, the silicon surface roughness induced by the plasma decreases by up to a factor of 3 when RF power is applied to the antenna.

This small modification of the etching reactor improves the control of the plasma parameters and enhances the etching process performance.

[  Back ]    [  Main  ]


14th ICMP, 1999, p.24-8
 

THE APPLICABILITY OF LANGMUIR PROBES FOR END POINT DETECTION OF POLYMER ETCHING

R.M. de Castro, P. Verdonck, M.B. Pisani, R.D. Mansano, G.A. Cirino, H.S. Maciel, M. Massi

Abstract

The adequate determination of the endpoint of a plasma etching process is very important for integrated circuit fabrication. In this paper, the authors propose a new method, making use of the floating potential, as determined by a single Langmuir probe with a RF choke. For the etching of a polymer film with an oxygen plasma, this method yields a reproducible and reliable signal, which was successfully used to detect the endpoint for several wafers. It is better than the method using de DC self-bias voltage as the endpoint detection signal, and approximately as good as when using emission spectrometry, whereas it uses a much cheaper equipment set.

[  Back ]    [  Main  ]


Contributions to Plasma Physics, v.39, n.3, p.235-46, 1999.

A COMPARATIVE STUDY OF SINGLE AND DOUBLE LANGMUIR PROBE TECHNIQUES FOR RF PLASMA CHARACTERIZATION

R.M. Castro, G.A. Cirino, P. Verdonck, H.S. Maciel, M. Massi, M.B. Pisani, R.D. Mansano

Abstract

In this study, the plasma density and electrons temperature of radio frequency (RF) plasmas were determined by three types of Langmuir probes, namely a conventional double probe, a single probe with RF choke and a single probe with RF choke and compensating electrode. The same plasmas were characterized by the three probes, each performing three measurements per plasma condition, in order to determine the precision of the measurement results. After performing a comparative analysis, which looked at the precision and the accuracy of these results, the conclusion is that the double probe, which has already the advantage of the simplest construction, yields the most reliable results for both capacitively and inductively coupled RF plasmas. The single probe with RF choke and compensating electrode has a similar precision as the single probe without compensating electrode, but the accuracy is better.

[  Back ]    [  Main ]


13th ICMP, 1998, v.1, p.598-14

COMPARISON BETWEEN SINGLE AND DOUBLE LANGMUIR PROBE TECHNIQUES FOR ANALYSIS OF INDUCTIVELY COUPLED PLASMAS

R.M. Castro, G.A. Cirino, P. Verdonck, H.S. Maciel *, M. Massi *, M.B. Pisani, R.D. Mansano
LSI PEE EPUSP
* Departamento de Física, ITA

In this study, the plasma density and electron temperature of Inductively Coupled Plasmas were determined by three types of Langmuir probes: a double probe, a single probe with RF choke and a single probe with RF choke and compensating electrode. The results obtained by the double probe offered the most reliable results for both plasma parameters. The single probe with compensating electrode has a similar precision as the single probe with only a RF choke, but its accuracy is better. For the investigated argon plasmas, the electron temperature increases with coil power and decreases with pressure, while the cathode power does not influence very much. The plasma density increases mainly with coil power, and to a lesser extent also with pressure and cathode power.

[  Back ]    [  Main  ]



 

2. Comunicações Técnicas, Apresentações Orais, Painéis / Technical Communications, Oral Presentations, Panels



6th Brazilian Plasma Physics Meeting (submitted, not accepted / published yet)

RF ELECTRICAL MEASUREMENTS IN RIE ARGON AND SF6 DISCHARGES

Marcelo B. Pisani, Patrick Verdonck – LSI-EPUSP

This work shows the development and the use of an RF electrical measurement system in an microelectronics RIE plasma etching tool in order to observe the electrical behavior of argon and SF6 plasmas.

Electrical measurements has proved to be an important diagnose tool in plasma processing, since the observed electrical properties are strongly related to the fundamental properties of the plasma and could be used to evaluate process characteristics and performance.

The studied process chamber has a volume of about 30 L and the powered electrode has 150 mm diameter (177 cm2 of area). RF power is provided by an Advanced Energy RFX-600 generator, working at 13.56 MHz fixed frequency and up to 600 W of power.

We developed an automatic data acquisition and calibration system to perform the measurements. We attached a Tektronix A6302 current probe and a P6007 high-voltage probe as near as possible to the powered electrode in order to avoid parasitic impedance's effect. We measured plasma current and voltage waveforms through a digital oscilloscope. A developed software in HP-VEE 4.01 calculates the chamber and plasma electrical parameters. To produce significant results, the system must be calibrated in phase, amplitude and compensated for the parasitics of electrical probes and process chamber.

The most important parasitic elements observed and the effects in the measurements were: the probes capacitance (of about 5.6 pF) and distance of placement to the plasma electrode (6 cm), witch makes the impedance moduli to be underestimated; the electrode connection inductance (makes observed voltage peak underestimated), and the inter-electrode large capacitance (of about 100 pF), witch makes the observed current highly overestimated.

We observed argon and SF6 pure discharges varying RF generator power (10 -- 100 W) and gas pressures (3 -- 27 Pa). The observed properties were the voltage and current peak, the complex impedance of the plasma (and then the plasma bulk resistance and sheath capacitance) and the true mean power delivered to the discharge.

Measurements in argon plasmas showed the strong capacitive behavior of this kind of discharge, and a poor precision in power calculation due to it. SF6 discharges exhibited more resistive impedance values mainly related to the high electronegativity of this kind of discharge and the power calculation gave better results. We showed that angles higher than 70 -- 800 in modulus induce an exaggerated uncertainty in the power calculation.

The plasma bulk resistance values observed were in the 50 -- 1 kohm; range for SF6 and in the 50 -- 300 ohm range for argon. The sheath capacitances are in the range of 20 -- 200 pF for SF6 and between 15 and 50 pF for argon. The impedance phase angle is between -87 and –600 for all the measures.

[  Back ]    [  Main  ]


6th Brazilian Plasma Physics Meeting (submitted, not accepted / published yet)

SINGLE, DOUBLE AND FLOATING LANGMUIR PROBE MEASUREMENT SYSTEM FOR RF DISCHARGE STUDIES

Marcelo B. Pisani, Raul M. de Castro, Giuseppe A. Cirino, Patrick Verdonck
LSI-EPUSP

This work shows a simple, versatile and low-cost system designed for single and double Langmuir probe data acquisition and processing. This apparatus is being applied to study microelectronics RF discharges.

The system is based on home-made cylindrical wire Langmuir probes, a DC variable source for probe excitation, a voltage and current measurement circuit, an analog-to-digital converter board that digitize the I--V data to a PC computer, and a computer program which controls instrument calibration, displays the curves in real time and documents the obtained voltage and current data. A second program written in Matlab displays and analyzes the curves, calculates the results for the electron temperature, ion current and ion density. The measurement system is electrically insulated from the discharge in order to avoid plasma disturbs and RF noise interference over the low measured currents.

The system works in three distinct ways. The first uses only one excited wire (single probe), with voltages from -60 to +60 V, measuring currents from -10 to 10 mA. The second runs in double probe mode, providing voltages from -200 to +200 V and measured currents from -200 to +200 microA. The –200 V polarization is also used to clean the probe surfaces from plasma contamination. In a third mode, no polarization is applied to the probe and only the plasma imposed potential is acquired. The floating measurement have shown to be an useful tool for plasma etching end-point detection.

[  Back ]    [  Main  ]


20th Cebravic, 1999, p.65, ref.068

UTILIZAÇÃO DE PLASMAS INDUTIVOS PARA CORROSÃO DE SILÍCIO

Marcelo B. Pisani, Patrick Verdonck
LSI/PEE/EPUSP – São Paulo – SP

Plasmas indutivos têm sido muito utilizados em aplicações de microeletrônica - para as quais se desejam em geral perfis verticais aliados a altas taxas de corrosão. Com estes plasmas, é possível se obter taxas da ordem de 1 micrometros/min em pressões abaixo de 1 Pa. Neste trabalho utilizamos uma configuração de reator tipo ICP ("inductively coupled plasma") construída em nosso laboratório a partir da adaptação de um reator RIE no qual se introduziu um indutor planar interno. A utilização de um indutor interno proporcionou taxas de corrosão maiores do que quando o mesmo é posicionado externamente, devido a uma maior eficiência de acoplamento de potência entre gerador e plasma. Foram estudadas características de transferência de potência de RF (13,56 MHz) entre gerador e plasma por espectrofotometria e pela medida da tensão de auto-polarização no eletrodo capacitivo em função dos parâmetros de processo (pressão e potência de plasma para uma vazão de SF6 mantida constante em 25 sccm). Foi estudado um processo de corrosão de silício de alta taxa e de perfil isotrópico utilizando-se SF6 puro e variando-se as condições de processo (pressão e potência de plasma). Os resultados mostram que a taxa de corrosão aumenta com a potência de plasma, e, com relação à pressão, atinge um máximo em torno de 20 Pa. Este processo terá aplicações como: isolação de dispositivos eletrônicos de potência, construção de microcanais arredondados de baixa rugosidade e construção de pilares ou pontas emissoras de campo em silício, entre outras.

[  Back ]    [  Main  ]


18th Cebravic, 1997, n.p., ref.051

APLICAÇÃO DE PLASMAS DE BAIXA FREQÜÊNCIA EM PROCESSOS DE CORROSÃO DE SILÍCIO E FOTORRESISTE

Marcelo B. Pisani, Ronaldo D. Mansano, Patrick Verdonck
LSI/PEE/EPUSP – São Paulo – SP

Neste trabalho são aplicados plasmas de 25 kHz em processos de corrosão para microeletrônica no lugar de plasmas de RF (realizados tipicamente a 13,56 MHz). A principal motivação em se utilizar baixas freqüências em substituição à RF é a obtenção de perfis mais anisotrópicos. Este fato está relacionado basicamente ao maior ataque iônico que é desfavorecido em regime de RF, dada a menor resposta dos íons a freqüência maiores. Foi utilizado um reator tipo RIE de lâmina única, onde a lâmina é diretamente ligada ao eletrodo. A corrosão de silício foi feita em ambiente de SF6 e a de fotorresiste em ambiente de O2, em pressões na faixa de 50 a 200 mTorr. Obteve-se taxas de corrosão da ordem de 1,2 micra/min para silício e 0,5 micron/min para fotorresiste, para potências aplicadas em torno de 50 W. Os resultados obtidos aponta para uma taxa de corrosão semelhante à conseguida em processos RF nas mesmas condições. A rugosidade relativa observada para alguns perfis de silício (em torno de 0,5 % da altura corroída) mostrou-se cerca de uma ordem de grandeza maior do que a obtida para processos RF, efeito que deve estar ligado à maior atividade iônica deste tipo de processo.

[  Back ]    [  Main  ]


44th National Symposium of AVS, Oct. 20-24, 1997, p.46, ref. PS-MoP19

PERFORMANCE CHARACTERISATION OF A RIE REACTOR WITH A BUILT-IN EXCITATION COIL

M. Massi, R.D. Mansano, P.B. Verdonck, H.S. Maciel *, M.B. Pisani, G.A. Cirino
University of São Paulo, Brazil
* ITA, Brazil

Into a home built plasma reactive ion etching system, an aluminum RF coil was inserted to induce an inductively coupled plasma. Using compensated Langmuir probes, the floating and plasma potentials, electron density and temperature and ion densities were measured at mid-distance between cathode and coil. For 10 mTorr Ar plasmas with 50 W power applied to the cathode, increasing power to the coil from 0 to 25 W, increases the electron density with a factor of 15 and decreases the electron temperature by approximately 20%. This 25 W inductive power also leads to an increase of +200 V and +20 V of the DC bias voltage and plasma potential respectively, in this way decreasing substantially the ion bombardment on the cathode. When no power is applied to the cathode, positive DC bias voltages can be obtained at this electrode, depending on the coil power. SF6 plasmas were applied to etch monocrystalline silicon and showed the following trends: at 25 mTorr pressure and for the 50 -- 150 W cathode power range, an increase of the etch rate of approximately 250 nm/min was observed, when 50 W power was applied to the coil (without coil power, the Si etch rate is 750 nm/min for 50 W cathode power). For increasing pressures, the influence of the coil power on the etch rate decreases, and is negligible for pressures higher than 100 mTorr. 5 sccm SF6-15 sccm Ar plasmas with 100 W cathode power and 25 W coil power result in a anisotropy of 0.85 at 34 mTorr, while without coil power nearly isotropic etchings are obtained. Metal contamination on a silicon wafer, exposed to a plasma induced by a stainless steel RF coil was measured by TRXF and showed a reduced density of metal atoms at the surface, compared with the contamination generated by a RIE plasma with a stainless steel electrode. Finally, one can conclude that the addition of independent RF power to a RIE system through an internal inductive coil can be used as a mean to improve the control of the plasma parameters and to enhance the etching process performance.

[  Back ]    [  Main  ]


16th Cebravic, 1995, n.p., ref.064

PROJETO E CARACTERIZAÇÃO DE UM GERADOR DE BAIXAS FREQÜÊNCIAS APLICADO À CORROSÃO POR PLASMA

Marcelo B. Pisani, Ronaldo D. Mansano, Patrick B. Verdonck
LSI/PEE/EPUSP – São Paulo – SP

Nos processos de corrosão por plasma um dos resultados mais importantes é a anisotropia dos perfis obtidos após a corrosão. Este resultado pode ser conseguido mais facilmente através de plasmas de baixa freqüência. Neste trabalho é apresentado o projeto e caracterização de um gerador de baixas freqüências de 25, 50 e 100 kHz, com potência máxima de 150 W. Este gerador foi acoplado a um sistema planar “single wafer” de corrosão por plasma. A caracterização deste equipamento foi feita através de medidas de transferência de potência, tensão DC e geração de plasmas em ambientes de N2 e O2. Uma primeira aplicação para este gerador é a corrosão da camada de resiste inferior num processo litográfico de 3 camadas.

[  Back ]    [  Main  ]


13th Cebravic, 1992, n.p., ref.060

PROJETO E CONSTRUÇÃO DE UM EQUIPAMENTO PARA CORROSÃO DE ALUMÍNIO POR PLASMA

Renato M. Franzin, Patrick Verdonck, Ronaldo Mansano, Nelson Ordonez, Marcelo B. Pisani
LSI-PEE/EPUSP

A corrosão de alumínio é uma das etapas mais críticas na obtenção de circuitos integrados. Além da problemática do controle das dimensões críticas dos circuitos, existem problemas relacionados à absorção de água pelos polímeros depositados nas paredes do equipamento e dessorção de produtos clorados tóxicos. Torna-se conveniente a utilização de equipamentos tipo “load-lock” onde existem várias câmaras, sen que apenas uma, a de entrada-saída, entre em contato direto com a atmosfera, as outras sempre ficam em vácuo. Baseado nessa filosofia foi projetado e construído um equipamento de corrosão por plasma tipo lâmina única, constituído por três câmaras: uma câmara para entrada-saída, uma câmara de transporte e a câmara para corrosão por plasma, tipo RIE. Futuramente será acoplada uma segunda câmara de corrosão por plasma para remoção de fotorresiste em seguida à corrosão do alumínio. A última abertura da câmara de transporte pode ser utilizada para acoplar outro equipamento. A câmara de corrosão conta com cinco controladores de fluxo de massa, controle de pressão automático, gerador de RF de 600 W a 13,56 MHz, malha de acoplamento automática, saídas para acoplamento de espectrômetro de emissão e de massa, sonda de Langmuir, etc.

[  Back ]    [  Main  ]