| 摘要 |
A charge amplifying memory cell and its method of making based on trench technology. A trench is formed which reaches through an n-type well region (32) to a p<+>-type substrate (30). A triple layer (36, 38, 40) is formed on two sidewalls of the trench consisting of two capacitive insulating layers and a intermediate p<+> polysilicon layer. The trench is then at least partially filled with a conductor, such as polysilicon (42), facing the triple layer. Thereby, the intermediate polysilicon layer acts as a charge storage node with capacitance to both the substrate and the polysilicon filling the trench. The insulating layer facing the well is opened with a contact hole near its top so that a p<+> transistor drain (44) is formed in the adjacent well by diffusion from the polysilicon through the contact hole. A p<+> transistor source (50) is doped into the well with a gate region between it and the drain to provide a write transistor. A p+ region (46) is also formed adjacent a sidewall of the trench other than the one containing the contact hole so that a read transistor is vertically formed in the n-type well between it and the substrate. The intermediate p<+> polysilicon layer acts as the electrode of this read transistor, whereby stored charge is amplified by the read transistor. |
