Gas-phase ion chemistry of silyl cations obtained from hexamethyldisilazane

Abstract

The gas-phase ion-molecule reactions of the Me3SiN(H)SiMe2+ ion, obtained by electron ionization from Me3SiN(H)SiMe3, have been studied in a Fourier transform ion cyclotron resonance spectrometer in order to understand the mechanistic details of an important chemical system presently used in film formation. This silyl cation has been observed to undergo addition reactions at electron rich centers to form stable adducts that may undergo further methane elimination in the case of alcohols and amines. The most important feature of these reactions is the fact that a metathesis type reaction can be observed in the presence of H2O, and other hydrogen labile substrates like alcohols, leading to the formation of the corresponding oxygen-containing ion, i.e. Me3SiOSiMe2+. For alcohols (ROH), facile formation of a tertiary product ion, presumably corresponding to an Me3Si-O-Si(Me)=O+-R structure with elimination of an amine reveals the strong tendency of these nitrogen-containing ions to undergo metathesis type reactions with oxygen containing substrates

Large Surface Area of HMDS Plasma Polymerized Thin Film Used for Production of Miniaturized Structures

“…If the plasma column reaches the cathode due to a powered auxiliary electrode, the bombardment increases and a rough film can be produced. Furthermore, silicon compounds deposition is mainly dependent on ion/molecule reactions [8]. Therefore with a second injection system near the cathode, not only neutral species become available to the impingent ions in the plasma region but also these species can adsorb on the surface and be hit by ions.…”

Comparative study on the deposition of silicon oxide permeation barrier coatings for polymers using hexamethyldisilazane (HMDSN) and hexamethyldisiloxane (HMDSO)

“…Under consideration of the mass dependent transmission function, figure 2 shows the MS detector signal of generic ion fragments of HMDSO and HMDSN, generated by electron impact in the ionizer, as a function of electron energy. Three exemplary ion fragments of HMDSO and HMDSN, that were produced by DEII and reported in literature, were chosen: (i) HMDSO and HMDSN molecules, which lost one methyl group ((CH 3 ) 3 SiOSi(CH 3 ) + 2 : 147 u; (CH 3 ) 3 SiNHSi(CH 3 ) + 2 : 146 u) [45,46], (ii) HMDSO and HMDSN molecules, which lost two methyl groups and one hydrogen atom ((CH 3 ) 3 SiOSi(CH 2 ) + : 131 u; (CH 3 ) 3 SiNSi(CH 3 ) + : 130 u) [46,55], (iii) HMDSO and HMDSN molecules that lost one Si containing group ((CH 3 ) 3 SiO + : 89 u; (CH 3 ) 3 SiNH + : 88 u) [45,59,60].…”

“…Dissociation and reaction pathways in plasma processes of HMDSO and HMDSN [10,[45][46][47][48][49][50] as well as SiO x film growth [14][15][16][17][18][22][23][24][25][26][27] have been stated in literature. However, only little work has been published containing a systematic comparison of HMDSO and HMDSN based coatings, applied as interlayers and SiO x barrier coatings on polymers, under the same conditions, within the same setup and on equal substrates [51].…”

Gas-phase solvolysis type reactions of SiCl3+ cations

“…2 The gas-phase ion chemistry of R 3 Si + ions has been studied in some detail 3 and they are known to be powerful electrophiles that can readily promote reactions by addition-elimination type mechanisms. 4 Our group has studied several aspects of the gas-phase ion/molecule reactions of the tetralkoxysilanes [5][6][7][8] because of the role that these substrates play as precursors of both, sol-gel processes relevant to functional materials, and CVD processes relevant to microelectronics. Silicon tetrahalides, and particularly the fluoro and chloro derivatives, are also known to be intimately related to CVD processes and SiCl 4 and the hydrolysis and ammonolysis of the neutral substrates have been characterized both experimentally 9 and theoretically.…”