Development of ultrasonic-based canister to increase the efficiency of the iCVD thin film process

The demand for high-density semiconductors is increasing as smart electronics have become essential. Several studies have been conducted on increasing the production capacity of high-density semiconductors, including thin film processes. This article narrates how we developed a novel canister, a crucial element of deposition equipment, to enhance the deposition efficiency of advanced processes such as initiated Chemical Vapor Deposition (iCVD). An ultrasonic-based canister was devised using an ultrasonic transducer installed at the bottom of an aluminum canister, with a heating jacket wrapped around the outside wall. The design exploits ultrasonic atomization to generate fine droplets, increasing precursor delivery to the reaction chamber. First, the viscosities and surface tensions of various liquid precursors were determined to correlate with the atomization rate and physicochemical characteristics of the precursors. We used a built testbed to determine the atomization rate; this rate and the properties of the precursors were found inversely proportional to viscosity and directly proportional to surface tension. A comparison of the vaporization rate of Divinylbenzene (DVB) using the conventional heating method and the ultrasonic-based canister method showed an improvement of approximately 250 %. To evaluate the applicability of the ultrasonic-based canister in the deposition process, a customized iCVD reactor system was fabricated, and the deposition process was carried out using DVB as the monomer and Tert-butyl peroxide (TBPO) as the initiator for depositing thin films. To evaluate the formed poly(Divinylbenzene) (p(DVB)), we conducted contact angle measurements, Fourier-Transform Infrared Spectroscopy (FT-IR) analysis, and X-ray Photoelectron Spectroscopy (XPS) analysis, and confirmed that the thin films had been successfully deposited, reflecting the characteristics of each chemical structure. For an efficiency comparison, the film thickness was measured using an ellipsometer deposited under identical conditions, using both the conventional heating method and the ultrasonic-based canister method. We confirmed that the specimen deposition rate obtained using the ultrasonic-based canister method formed a film that was approximately 300 % faster than using the conventional method. This study successfully demonstrates that an ultrasonic-based canister significantly enhances the deposition rate and validates its practical applicability in deposition processes.