Sains Malaysiana 38(4)(2009): 553–557 

Statistical Design of Ultra-Thin SiO₂ for Nanodevices

(Reka bentuk Statistik SiO₂ Ultranipis untuk Nanoperanti)

U. Hashim*

Institute of Nano Electronic Engineering (INEE)

Universiti Malaysia Perlis, 01000 Kangar, Perlis, Malaysia

M.F.A. Abdul Fatah, I. Ahmad & B.Y. Majlis

Department of Electrical, Electronics and System Engineering

Faculty of Engineering, Universiti Kebangsaan Malaysia

43600 Bangi, Selangor D.E., Malaysia

Diserahkan: 2 Mei 2008/ Diterima: 4 Disember 2008

ABSTRACT

A study was performed on a series of ultra thin SiO₂ films in order to determine the factors affecting the oxide growth and also the effect of temperature to the film surface roughness. The samples of ultra thin SiO₂ were prepared through a dry oxidation method using a high temperature furnace. There are three levels of temperature used, that is 900, 950 and 1000°C and the samples were grown at 0.333 litre/min, 0.667 liter/min and 1 liter/min oxygen flow rate and different oxidation times of 1, 2 and 3 minutes. The thickness was determined using an elipsometer and the micro morphology of the oxide surface was obtained by using an atomic force microscope (AFM). The thickness of the oxide ranged from 1 to 5 nm. All the data has been interpreted using Taguchi’s method to analyze the most affecting factors in producing an ultra thin silicon dioxide. The optimum parameters are 900°C, 0.333 litre/min and at 1 minute time. The most influencial parameter is temperature. The temperature also affects the surface roughness. The AFM result of 950°C with RMS value of 0.1088 nm is better than the 900°C oxide with RMS value 0.4553 nm. This shows that oxides need to be grown at a higher temperature to provide better surface roughness which is also important in ultra thin gate oxide characteristics.

Keywords: Atomic force microscopy (AFM); CMOS; gate dielectrics; silicon dioxide; Taguchi’s method; ultra-thin gate oxide

ABSTRAK

Kajian telah dijalankan ke atas beberapa siri lapisan SiO₂ ultranipis untuk menentukan faktor-faktor yang mempengaruhi pertumbuhan oksida dan juga kesan suhu terhadap kekasaran permukaan lapisan. Sampel SiO₂ lampau nipis telah disediakan melalui kaedah pengoksidaan kering menggunakan relau bersuhu tinggi. Terdapat tiga peringkat suhu yang digunakan iaitu 900, 950 dan 1000°C dan sampel telah ditumbuhkan dalam 0.333 liter/min, 0.667 liter/min dan 1 liter/ min dan perbezaan masa pengoksidaan, 1, 2 dan aliran oksigen pada kadar 3 minit. Pencirian ketebalan dilakukan dengan menggunakan elipsometer dan mikromorfologi bagi permukaan oksida diperolehi menggunakan mikroskop daya atom (AFM). Ketebalan oksida yang diperolehi adalah dalam julat 1 hingga 5 nm. Semua data yang diperolehi dianalisis menggunakan kaedah Taguchi untuk menganalisis faktor-faktor yang paling mempengaruhi penghasilan SiO₂ ultranipis. Parameter yang paling optimum ialah 900°C, 0.333 liter/min pada masa 1 minit. Faktor yang paling mempengaruhi prosess ini ialah suhu tetapi suhu juga mempengaruhi kekasaran permukaan. Keputusan AFM pada 950°C dengan nilai RMS 0.1088 nm adalah yang paling baik berbanding pada 900°C dengan nilai RMS 0.4553 nm. Kajian ini membuktikan bahawa pertumbuhan oksida perlu dilakukan pada suhu tinggi untuk menghasilkan kekasaran permukaan yang lebih baik yang juga amat penting bagi ciri get oksida ultranipis.

Kata kunci: CMOS; get oksida ultranipis; get dielektrik; kaedah Taguchi; mikroskop daya atom (AFM); silikon dioksida

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*Pengarang untuk surat-menyurat; email: uda@unimap.edu.my