Method for enhancing field oxide and integrated circuit with enhanced field oxide

Abstract

A CMOS device with polysilicon protection tiles is shown in Figure 2. LOCOS regions (12.1) and (12.2) separate adjacent active regions (16.1) from (16) and (18.1) from (18), respectively. On the upper surface of the LOCOS regions (12.1, 12.2) are polysilicon tiles (14.1, 14.2), respectively. At the corner of the gate polysilicon (14.3) and the polysilicon tiles (14.1 and 14.2) are oxide spacers (60.1-60.6). The polysilicon tiles (14.1, 14.2) have silicide layers (50.1, 50.2). Other silicide layers (50.4-50.6) are on the tops of the source, drain and polysilicon gate. An insulation layer (32) covers the substrate and metal contacts (36, 34, 38) extend from the surface of the layer (32) to the silicide layers on the source, gate and drain, respectively. The polysilicon tiles are made from the same layer of polysilicon as the gate and they are formed simultaneously with the gates. The intention of the polysilicon tiles is to reduce erosion of the field oxide between closely spaced active regions. In addition, the poly tiles themselves increase the thickness of the isolation between active silicon regions when it must serve as a self-aligned blocking layer for an ion implantation step.

Description

[0001] Cross References to Related Applications [0002] This application claims priority to US Patent Application Serial No. 10 / 857,218, filed May 28,2004. technical field [0003] none Background technique [0004] Local oxidation of silicon (LOCOS) isolation methods are widely used in many processes in the manufacture of semiconductor integrated circuits. Using LOCOS, active silicon regions on the surface of a single crystal silicon substrate or silicon epitaxial layer can be electrically isolated by relatively thick insulating oxide regions. Deposited silicon nitride (Si 3 N 4 ) to suppress oxide growth selectively where active silicon is desired. Devices such as diodes, transistors, resistors, capacitors and other microelectronic structures are then built in these active silicon regions between the insulating oxide regions. This electrical isolation is necessary to prevent unwanted device-to-device electrical interactions. [0005] The LOCOS process begins with t...

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Problems solved by technology

But those trench techniques further increase the processing steps and thus the manufacturing cost of integrated circuits

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