Selective nucleation in silicon moulds for diamond MEMS fabrication

Abstract

We present a new and original approach for the fabrication of diamond MEMS using MPCVD. This process does not rely on diamond etching using conventional techniques such as e.g. RIE: here our MEMS structures are geometrically defined using silicon moulds in which diamond is grown selectively. The moulds can be prepared from silicon using DRIE and enabling a wide range of geometries. The critical point is the selectivity of diamond growth which dramatically depends on the nucleation process. Two nucleation methods for selective diamond growth inside silicon moulds were explored in parallel and compared, namely, the bias enhanced nucleation (BEN) and the nano-seeding technique. With both methods, MEMS structures were successfully fabricated and characterized, leading to values for the Young modulus above 830 GPa, thus comparing well with literature values. We believe our approach will ease the routine fabrication of large area diamond MEMS wafers for improved advanced device fabrication.

Toward surface‐friendly treatment of seeding layer and selected‐area diamond growth

“…Consequently, the growth of porous diamond structures was observed in those areas. Previously it was shown that metal mask allowed a prolonged plasma etching time up to 20 min, see the work of Bongrain et al [2]. In such case, the residual density of parasitic crystal decreased down to 5 Â 10 5 cm À2 .…”

“…Adequately, developing of a suitable structuring technique is needed for realization of any device [1,2]. However, diamond chemical inertness and mechanical hardness make conventional structuring methods less favorable.…”

“…A direct growth of diamond structures represents alternative solution. The direct growth, also known as selected-area deposition (SAD), is mostly realized by applying the treatment of seeding (i.e., nucleation) layer before the diamond growth [1,2].…”

“…The main advantages of all above described strategies are: (i) omitting any destructive treatment of substrate, e.g., its rinsing in acid to remove metal mask [1,2], (ii) easy applications on large-area substrates, (iii) suitability for diverse substrate materials, and (iv) compatibility with standard semiconductor processes.…”

Technological Aspects in Fabrication of Micro- and Nano-Sized Carbon Based Features: Nanorods, Periodical Arrays and Self-Standing Membranes

“…Various pre-or post growth techniques have been developed to fabricate surfaces of wished features. Only briefly, these techniques include reactive ion etching [7,8] involving EBL [9], ink-jet printing of diamond seeds [10], selective area deposition [11,12] including selective etching of substrate [13]. However, only a limited number of above mentioned techniques allows the fabrication of geometrically ordered arrays or templates.…”