Low-Temperature Deposition of Silicon Oxide Films

Abstract

Silicon oxide films play an important role in semiconductor device technology. Surface passivation and diffusion masking are the most prominent applications for these amorphous films. There are several methods by which such oxide films may be obtained, but only the elevated temperature processes give satisfactory oxide films for the abovementioned applications.Decomposition of organic compounds on the absorption of energy is a well-known phenomenon. The necessary energy may be supplied as chemical energy, thermal energy or in the form of radiation (ultraviolet, gamma radiation, etc.). The composition of the decomposition products depends on the nature of the starting material, as well as on the experimental conditions. Consequently, it is difficult if not impossible to predict the nature and composition of all the products of such decomposition. Nevertheless, one can expect the formation of certain compounds from thermodynamic considerations. Thus, the thermal decomposition of aluminum isopropoxide is expected to give aluminum oxide under favorable conditions.The difficulties encountered in electron optical systems lead to the discovery (1, 2) that organic compounds decompose when subjected to an electron beam. The discovery was followed by the development of the method of forming thin polymeric and metallic films by electron bombardment of suitable chemical compounds (3-5).The well-known phenomenon of direct current glow discharge was used for preparation of thin films at the Electronics Laboratory of General Electric Company (6). The work reported here followed the same basic principle, except that R.F. induced gaseous plasma was used in order to eliminate the undesirable sDuttering observed with d-c glow discharge.We have developed a method by which a uniform and amorphous silicon oxide film may be deposited at nearly room temperature. In our process a suitable organo-silicon compound is decomposed in a low energy gaseous plasma to give a silicon oxide film and various other decomposition products which are prevented from depositing on the substrate by the continuous bombardment of the surface. Among the many organo-silicon compounds alkoxy-silanes were found to be most suitable. Due to the favorable silicon to oxygen ratio, these compounds may be used successfully with argon plasmas. It follows that oxygen must be added to the system if the silicon to oxygen ratio is too low.We propose the following tentative mechanism for the reaction. The excited or ionized gas atoms

Light-induced anodisation of silicon for solar cell passivation

“…Alternatively, the silicon dioxide films can be formed at low temperatures by rapid thermal oxidation (RTO), [14][15][16][17][18] plasma enhanced chemical vapour deposition (PECVD), [19][20][21][22] atomic-layer deposition (ALD), [23][24][25][26][27] atmospheric pressure chemical vapour deposition (APCVD), 22,28,29 nitric acid oxidation of silicon (NAOS), [30][31][32][33] and anodic oxidation. [34][35][36][37][38][39] The advantages and disadvantages of these different methods were discussed by Grant 40 who recently reported surface recombination velocities of less than 40 cm/s on silicon wafers passivated with silicon dioxide layers that were electrochemically grown in nitric acid at room temperature.…”

Plasma-Enhanced Chemical Vapor Deposition: Where we are and the Outlook for the Future

“…The initial experiments using plasma in the CVD process dates back to 1950s and 1960s when the decomposition of organic compounds in the presence of an electron beam was first observed [8][9][10]. In the electro-optical systems, when a surface was exposed to an electron beam, it was covered by a thin film.…”

“…Upon observing this effect, researchers reasoned that the formation of the thin film was due to the interactions between the electron beam and organic vapor present in the vacuum system. They concluded that the mechanism of formation of the thin layer was the free radical polymerization of the organic molecules, upon exposure to the electron beam followed by adherence to the target surface [8][9][10]. After roughly a decade, Buck et al suggested that the observed mechanism of film formation can be beneficial for applications where thin insulating films were required [11].…”

“…Among the initial reports on the use of PECVD, there was one in 1962, in the Electronics Laboratory of General Electric Company for the utilization of the direct current glow discharge system for the production of thin films [13]. Laendle et al reported the use of an organosilicon compound and its decomposition in a low-energy plasma to fabricate a silicon oxide film [10]. The decomposition reported was related to the collisions that occurred between the excited or ionized gas atoms with the organosilicon molecules, which in turn resulted in the formation of free radicals, followed by their attachment on the substrate and finally due to continuous bombardment, fabrication of stable Si-O-Si network and the resultant thin film.…”

From Carbon Nanostructures to New Photoluminescence Sources: An Overview of New Perspectives and Emerging Applications of Low‐Pressure PECVD

“…The early papers by S. W. Ing [1][2][3] and co-workers, published between 1963 and 1965 on low-temperature, plasmaenhanced CVD (or simply PECVD) deposition of silicon oxide films, could be considered as one of the first experimental reports on the possibility of using electric discharges in gases to produce plasmas that generate various types of reactive species for thin film deposition. These initial attempts were used for microelectronic applications and, in particular, for diffusion masks and passivation.…”