A voltage uniformity study in large-area reactors for RF plasma deposition

Abstract

Non-uniform voltage distribution across the electrode area results in inhomogeneous thin-film RF plasma deposition in large-area reactors. In this work, a two-dimensional analytic model for the calculation of the voltage distribution across the electrode area is presented. The results of this model are in good agreement with measurements performed without plasma at 13.56 MHz and 70 MHz in a large-area reactor. The principal voltage inhomogeneities are caused by logarithmic singularities in the vicinity of RF connections and not by standing waves. These singularities are only described by a two-dimensional model and cannot be intuitively predicted by analogy to a one-dimensional case. Plasma light emission measurements and thickness homogeneity studies of a-Si:H deposited films show that the plasma reproduces these voltage inhomogeneities. Improvement of the voltage uniformity is investigated by changing the number and position of the RF connections.

Hot wire configuration for depositing device grade nano-crystalline silicon at high deposition rate

“…No plasma is used to generate the radicals. Thus, the homogeneity of the film is not affected by the standing waves effect, characteristic of the PE-CVD technique [13,14]. This makes it easier to scale up the HW-CVD technique to large area without any loss in the film's homogeneity [15,16].…”

Large-area low-damage plasma sources driven by multiple low-inductance-antenna modules for next-generation flat-panel display processes

“…The plasma sources developed so far for production of large-area plasmas include capacitively-coupled plasmas (CCP) [1][2][3][4], inductivelycoupled plasmas (ICP) [1,[5][6][7][8][9] and surface wave plasmas (SWP) [10][11][12][13].…”

Large area VHF plasma production using a ladder-shaped electrode

“…This method has drawn attention because it can produce relatively high-quality films at a high speed. However, in the VHF range, it is hard to obtain uniform films over a large area because of the electrical voltage distribution caused by the standing wave effects on the surface of the conventional parallel plates electrodes [9,10].…”