High Density Cross-Point Cell in an Interleaved Sense Amplifier Layout
Original Publication Date: 1987-Oct-01
Included in the Prior Art Database: 2005-Feb-02
This article describes a high density cross point cell structure with segmented metal bit lines used in an interleaved sense amplifier layout. (Image Omitted) Many high density cross-point cells utilize a wide diffused bit line BL, as shown in Fig. 1, resulting in a cell area larger than necessary. Cell length along the word line (WL) axis is limited by the proximity of passing diffused bit lines. Also, the polysilicon (Poly) WL to diffused bit line (BL) overlap causes the WL to be lengthened, which impacts the word line RC time constant. By reducing the BL diffused area to a short segment between cell trenches and introducing a contact for a metal BL, as shown in Fig. 2, the cell area can be made smaller by shrinking the cell size along the WL axis.