Influence of reduced working frequencies on the floating‐zone growth of silicon single crystals

Menzel, Robert; Rost, Axel; Luedge, A.; Riemann, H.

doi:10.1002/crat.201100230

Cited by 5 publications

(4 citation statements)

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“…In FZ growth experiments arc discharges at the main slit reproducibly occurred without using a quartz plate in a pure Ar‐atmosphere during growth at cone diameters between 60 mm to 80 mm and frequencies of 2.8–3.0 MHz. These results agree with those found in previous experiments . Under equal process conditions, even under pure Ar‐atmosphere, a quartz plate allowed to increase the diameter of the crystal up to 125 mm, before arcing was observed.…”

Section: Resultsmentioning

confidence: 99%

“…A third option is a reduction of the frequency of the inductor current, as with lower frequency less voltage is required. Previously, it has been shown that reducing the frequency down to the range of 2 to 1.7 MHz prevents arcing for crystal diameters of 4–5 inch, at those experimental conditions were arcing occurred at higher frequencies between 2.8–3.0 MHz . Unfortunately, lower frequencies cause an inhomogeneous melting of the feed rod.…”

Section: Introductionmentioning

confidence: 99%

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Improvement of the growth stability for large diameter Si-float zone crystals by controlling the gas flow

Rost

Menzel

Riemann

et al. 2014

Phys. Status Solidi A

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For the growth of large float zone (FZ) silicon crystals, currently limited to 200 mm diameter, a high process stability is necessary. A major drawback are arc discharges at the inductor, when the increasing diameter of the growing crystal requires higher RF voltages. An arc discharge mostly interrupts the dislocation‐free growth of the crystal. Increasing the gas pressure or adding some nitrogen to the growth atmosphere increases its electrical strengths. For reduced working frequencies the inductor voltage is lowered, too. However, the usability of these measures is limited. The aim of this work was to investigate another concept to reduce the probability of arcing. Numerical calculations of the convective gas flow in a typical FZ puller revealed a high gas temperature, being close to the silicon melting point temperature in the vicinity of the melt surface. The gas temperature near the inductor and especially its influence on the risk of arcing, were investigated. Several experiments confirm a significantly higher breakdown voltage at lower temperature in comparable conditions by controlling the gas flow. This was performed using a thin quartz plate covering at least the whole lower inductor surface including the main slit where the electric field is strong. Therefore, the temperature will be lowered due to the separation of the hot gas flow from the critical slit region. It could been shown, that the risk of arcing could be noticeable reduced for 6 inch crystals grown under comparable conditions The results will be supported by global numerical simulations showing the flow field and the temperature distribution of the gas. The protection of the critical region by changing the gas flow appears as a new potent measure to prevent arcing and to enable larger crystals.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Improvement of the growth stability for large diameter Si-float zone crystals by controlling the gas flow

Rost

Menzel

Riemann

et al. 2014

Phys. Status Solidi A

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show abstract

“…Using the 4-point probe method, radial resistivity distributions were measured in the lateral direction, at a longitudinal cross-section of the cylindrical part of the grown crystals. Numerical simulations of the convection streams in the melt were made using the commercially available programs SINGULA and ANSYS [5]. To investigate the influence of reduced frequencies on the electrical breakthrough behavior (arcing), three crystals were grown at the corresponding frequencies using pure argon as growth atmosphere.…”

Section: Methodsmentioning

confidence: 99%

Float-Zone silicon crystal growth at reduced RF frequencies

Rost¹,

Menzel²,

Luedge³

et al. 2012

Journal of Crystal Growth

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“…Menzel [65] uses the measured interface shapes to calculate the 3D EM field of different frequencies using the commercial code SINGULA and applying these results for the calculation of 2D fluid flow using the commercial code ANSYS-CFX.…”

Section: Historical Overviewmentioning

confidence: 99%