DFCCP sources SCCMTE TEL ExelanCFE Lam Enalber AMT

DF-CCP sources SCCM-TE (TEL) Exelan-CFE (Lam) Enalber (AMT) D 92 SAC Etcher D 92 Si. N mask Etcher - ~ 60 MHz ~ ~ 2 MHz ~ 13. 56 MHz ▶ Dual-CCP 4. 5 cm, 30 m. T ▶ Uniformity : - Dual cathode ▶ Narrow Dual-CCP : 2. 0 cm, 40 m. T ▶ PR Selectivity : Heated top electrode 162 MHz ▶ VHF Dual-CCP : Very High Freq. 3. 2 cm, 30 m. T ▶ High E/R & PR Sel. :

Typical operating conditions for dielectric etching on 200 -300 mm silicon wafers are: discharge radius: R~15 -25 cm plate separation l~1 -5 cm high frequency fh ~27. 1 -160 MHz low frequency fl ~ 2 -13. 6 MHz high-frequency voltage amplitude |Vh| ~250 -1000 V low-frequency voltage amplitude |Vl| ~500 -3000 V powers for both low- and high-frequency sources: 500 -3000 W discharge pressure p ~30 -300 m. Torr

Method for suppressing standing-wave nonuniformity Shaped lower electrode L. Sansonnens et al. , J. Vac. Sci. Techn. A 24, 1 425 (2006)

三、 描述DF-CCP物理过程的解析模型 Ion density is homogeneous Electron density is step-like distributions Jrf(t)=Jlcos(wlt)+ Jhcos(wht)

Influence of high-frequency power on the plasma density VL= 400 V，f. L=2 MHz, d=2 cm, p=5 m. Torr

Influence of low-frequency on IEDF VL= 400 V，f. H=60 MHz, VH=200 V, d=2 cm, p=5 m. Torr

Fluid models: Ar plasmas ionization Electron flux Electron energy loss

离子在鞘层中受鞘层电场的运动 E(x, t) xj, vj Ion positions xj(t) and velocities vj(t) between two contiguous collisions. Please notice: the ion trajectory is a beeline under the action of the electric field.

One-dimensional model When the chamber radius R is far larger than the distance d between two electrodes, we can use the 1 D model to simulate the discharge, i. e. , R>>d. x=d x=0 LF HF

Influence of HF-power frequency on plasma density P = 100 m. Torr, Vh = 200 V, Vl =400 V fl = 2 MHz, fh = 20, 30, 60 MHz,

Influence of LF-power frequency on plasma density P=50 m. Torr, Vh=50 V, Vl=100 V, fh =60 MHz, fl=2, 5, 10, 13. 56 MHz

Influence of HF-power frequency on sheath voltage drop 平均鞘层电位降： P = 100 m. Torr, Vh = 200 V, Vl =400 V fl = 2 MHz, fh = 20, 30, 60 MHz, 与解析模型的比较

离子入射到电极上的能量分布 fh = 30 MHz, P =50 m. Torr, Vh = 200 V, Vl = 400 V fl = 2 MHz P = 100 m. Torr, Vh = 200 V, Vl = 400 V

Two-dimensional model 2 R H D LF power H= 2. 45 cm 2 R=43. 18 cm HF power Schematic diagram of DF-CCP D=6. 35 cm

I. Influence of high frequency f. H averaged electron density: 27 MHz 40 MHz 60 MHz VHF=50 V, VLF=100 V, f. L =2 MHz, p=100 m. Torr The electron density increases significantly as increasing values of f. L.

averaged electron temperature: 27 MHz 40 MHz 60 MHz VHF=50 V, VLF=100 V, f. L =2 MHz, p=100 m. Torr The electron density increases slightly as increasing values of f. L.

II. influence of low frequency averaged electron density: 2 MHz 6 MHz 12 MHz VHF=50 V, VLF=100 V, f. H =60 MHz, p=100 m. Torr With the increase of low frequency, two sources become from decoupling to coupling, and the electron density increases significantly when two sources coupling.

Averaged electron temperature: 2 MHz 6 MHz 12 MHz VHF=50 V, VLF=100 V, f. H =60 MHz, p=100 m. Torr With the increase of low frequency, the temperature of electrons increases slightly.

Ez in a LF period: VHF = 50 V, VLF = 100 V, f. LF = 2 MHz, f. HF = 60 MHz, p = 100 m. Torr

Er in a LF period: VHF = 50 V, VLF = 100 V, f. LF = 2 MHz, f. HF = 60 MHz, p = 100 m. Torr

Fluid simulations for CF 4 plasmas (1 D) 1. Basic model 2. CF 4 plasma is an electronegative discharge, i. e. , there 3. are no negative ions in the discharge. The plasma is 4. composed of neutrals (atoms and molecules), electrons, 5. positive ions, and negative ions.

There are more than 30 reaction equations in the discharge.

For simplification, we consider only four reaction processes, i. e. , Ionization: CF 4+e CF 3+ +F+2 e Attachment: CF 4+e CF 3 +FRecombination: CF 3+ + e CF 3 Dissociation: CF 4+e CF 3 +F + e and four species of particles: electrons, CF 4, CF 3+, F-

Plasma Physics Model (electrons and ions): Ki –ionization rate Ka –attachment rate Krec –recombination rate

Numerical results Influence of the discharge pressure on charged particle densities f. L = 2 MHz, f. H = 60 MHz, VL = 2000 V, VH = 1000 V, Ddielectric=0. 5 mm

Influence of the HF voltage on charged particle densities f. L = 2 MHz, f. H = 60 MHz, VL = 1000 V, p=100 m. Torr, Ddielectric=0. 5 mm

五、直流偏压效应 Positive charged accumulated on dielectric Local electric field within micro trough Side etching E

1 D PIC/MC simulations for Ar discharges

Our recent publications about simulations of DF-CCP 1. Z. Q. Guan, Z. L. Dai and Y. N. Wang “Simulations of dual rf-biased sheaths and ion energy distributions arriving at a dual rf-biased electrode ”, PHYSICS OF PLASMAS 12, 123502 (2005) 2. Z. L. Dai, X. Xu and Y. N. Wang “A self-consistent hybrid model of a dual frequency sheath: Ion energy and angular distributions ’’ , Phys. Plasmas 14, 013507 (2007) 3. W. Jiang, M. Mao and Y. N. Wang “A time-dependent analytical sheath model for dual-frequency capacitively coupled plasma ”, Phys. Plasmas 13, 113502 (2006) 4. S. Wang, X. Xu and Y. N. Wang “Numerical investigation of ion energy distribution and ion angle distribution in a dual-frequency capacitively couple plasma with a hybrid model”, be published in Physics of Plasmas

Next plan for our simulations Improving hybrid simulations, including 1 D simulations for CF 4/Ar discharges 2 D simulations for CF 4/Ar discharges Interesting quantities: Energy distribution functions of different species ions ( such as Ar+, CF 3+) at substrates; Angle distribution functions of different species ions ( such as Ar+, CF 3+) at substrates; Energy and angle distributions of radicals at substrates. Radial variations

Self-consistent study for the standing-wave effects in HF-CCP 2 D fluid model 2 D Maxwell equations

DF-CCP装置

Thanks for your attention!