We developed a new molecular beam deposition apparatus using a spray-jet technique for high-quality thin film preparation of nonsublimable molecules. The apparatus was used to deposit chloro[tri-tert-butyl-subphthalocyaninato]boront(III) (TBSubPc) molecules on an Au(111) surface for analysis by low-temperature scanning tunneling microscopy (STM). Highly resolved images, in which tert-butyl groups in a TBSubPc molecule were clearly identifiable, were obtained. The image quality and the resolution of these images compared favorably well to STM images taken on reference samples which were sublimed onto Au (111) from a heated crucible.