Investigation of the ion dose non-uniformity caused by sheath-lens focusing effect on silicon wafers

Holtzer, N.; Stamate, Eugen; Toyoda, Hirotaka; Sugai, Hideo

doi:10.1016/j.tsf.2006.10.099

Cited by 7 publications

(9 citation statements)

References 20 publications

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“…The analysis of the sheath structure also has interest in plasma diagnostics using Langmuir probes as well as plasma-sheath lens. [1][2][3] Negative ions in plasmas also have the positive effect of improving the performance of dry etching. 4 An example is the cancellation of positive charge accumulated on the wafer.…”

Section: Introductionmentioning

confidence: 99%

Structure of presheath-sheath in magnetized electronegative plasma

2009

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The structure of an electronegative discharge is investigated in the presence of an oblique, uniform, and constant magnetic field. For different magnetic field strengths, the densities of the positive ion, electron, as well as negative ion have been calculated. Furthermore, the profiles of positive ion's velocity and electric potential are obtained. Under high values of electronegativity and for sufficiently cold negative ions, different magnetic field values constitute three types of discharge structure. For a very small magnetic field strength, a uniform structure is formed; for an intermediate magnetic field, a stratified multiple layer structure emerges, which is followed by electric potential oscillations; while for an intense magnetic field, these oscillations disappear. The flux of the positive ion reaching the cathode as a function of the magnetic field strength is also obtained and the result is compared with the electropositive discharge.

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Section: Introductionmentioning

confidence: 99%

Structure of presheath-sheath in magnetized electronegative plasma

2009

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“…4,5) The insertion in Fig. 3 demonstrates an example of treated photograph of the wafer after 10-keV-40-ms oxygen ion implantation where R imp denotes the radius of the active area.…”

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confidence: 68%

“…1,3,4) In PIII, a negative high-voltage square-wave pulse is applied to a substrate immersed in a plasma where ions in the matrix sheath are extracted together with Bohm flux through a pre-sheath, and are accelerated by the strong sheath electric field toward the substrate. [5][6][7] Thus, the pulse amplitude V 0 and the pulse width T of applied voltage determine the incident ion energy and the total ion dose, for given plasma density and ion species, which in turn determine the depth profile of dopant concentration in the wafer surface.…”

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confidence: 99%

Using Transient Sheath Induced by Short High-voltage Pulse for Uniform Plasma Ion Implantation

Holtzer

Sugai

Saito

et al. 2007

jjap

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Plasma immersion ion implantation (PIII) is a useful technique for ultra-shallow doping in semiconductor processing. However, three-dimensional sheath-lens effect inevitably makes the ion dose distribution non-uniform. To minimize this nonuniformity, using a transient sheath induced by short pulse (< a few ms) is proposed and its usefulness is demonstrated in inductively coupled plasmas. Sheath expansion is measured after application of negative high voltage pulse with pulse width and voltage as parameters. Non-uniformity disappears with a decreasing pulse width from 40 to 0.3 ms. Comparison of N 2 þ with H 2 þ ion implantation showed that uniformity improves for heavier ion species. Implants depth profile secondary ion mass spectroscopy (SIMS) measurement revealed that short pulses realize shallow implantation for shorter process times.

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“…All data presented in this work refer to stationary sheaths (dc bias), and there was no need to take into account transient ion fluxes. However, we already reported some results on ion focusing in a pulsed sheath [31,39]. We hope that time dependent discrete and modal focusing features will attract interest form the scientific community, resulting in complex time dependent calculations.…”

Section: Discussionmentioning

confidence: 98%