United Microelectronics Corp.

Shih-Chieh Kao

Mu-Chun Wang

Shih-Chung Li

Shiang Huang-Lu

Yuan-Chang Liu

Yu-Yiu Lin

A gate dielectric breakdown test method is disclosed. The method includes performing a one step programmed VRDB test using Vcc voltage power source, gate current density for the corresponding ramped voltages are recorded. If the gate current density is found to be higher than a specified gate current density criterion, then the gate oxide is deemed to defective and is scrapped. And, if the gate current density (Jg) is found to be less than the specified gate current density criterion (Jc), then a differential gate current density ratio R&equals;&Dgr;Jg/Jg for the corresponding ramped voltages are calculated. If the R value is found to be less than a specified differential current density ratio criterion (Rc), then the gate dielectric is considered to be robust, and if the R value is greater than the Rc value, then the gate dielectric is considered to be inflected. Accordingly, the voltage Vg can be effectively used for justifying the integrity of the gate dielectric.

Method of determining integrity of a gate dielectric

A via plug layout structure for connecting different metallic layers. The structure includes a plurality of via plugs arranged in a fan-shaped pattern and a plurality of empty bars positioned between a single via plug and the fanned-out via plugs so that incoming current to the single via plug is equally distributed to every one of the fanned-out via plug and current stress in each fanned-out via plug is identical. Hence, via plugs having particularly serious electromigration problem can be discovered. In addition, single via plug having different critical dimension can be fabricated so that maximum critical dimension sustainable by the via plug is determined after an electromigration test.

Via plug layout structure for connecting different metallic layers

The present invention provides a method for preventing gate oxides on a semiconductor wafer from being damaged by electromagnetic waves or particles generated in a plasma-related process. The semiconductor wafer comprises a substrate, a plurality of gate oxides positioned separately on the substrate, a first dielectric layer positioned on the gate oxides for isolating the gate oxides, and a conducting layer positioned on the first dielectric layer having at least one testing slit with a predetermined test pattern installed above each of the gate oxides. The method first performs a predetermined plasma-related process on the surface of the semiconductor wafer. Next, an electrical test is performed to find damaged gate oxides out of the gate oxides on the substrate. Based on damages of the damaged gate oxides, the predetermined plasma-related process is adjusted to prevent gate oxides on other semiconductor wafers from being damaged in the predetermined plasma-related process.

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Hsinchu, Taiwan

Shih-Chieh Kao