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Ion Implant Test Structure

IP.com Disclosure Number: IPCOM000040855D
Original Publication Date: 1987-Feb-01
Included in the Prior Art Database: 2005-Feb-02
Document File: 1 page(s) / 12K

Publishing Venue

IBM

Related People

Divalentin, AV: AUTHOR [+4]

Abstract

The ion implant test structure can be used to simulate photore sist mask charging effects on sheet resistance on a monitor wafer. The vertical structure is given in Fig. 1. Patterned photoresist 10 is one to two microns thick. The screen oxide 20 is a thermal oxide film 20-100 nanometers thick. Substrate 30 is a P-type polished wafer used for measuring sheet resistance of N-type implants. The top view of the test structure on the monitor wafer 30 is given in Fig. 2. The photoresist pattern consists of nine open square windows, each about one centimeter by one centimeter.

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Ion Implant Test Structure

The ion implant test structure can be used to simulate photore sist mask charging effects on sheet resistance on a monitor wafer. The vertical structure is given in Fig. 1. Patterned photoresist 10 is one to two microns thick. The screen oxide 20 is a thermal oxide film 20-100 nanometers thick. Substrate 30 is a P- type polished wafer used for measuring sheet resistance of N-type implants. The top view of the test structure on the monitor wafer 30 is given in Fig. 2. The photoresist pattern consists of nine open square windows, each about one centimeter by one centimeter.

The ion implant test structure is used as follows. The monitor wafer 30 is arsenic implanted. The photoresist pattern 10 (Fig. 1) is removed in an oxygen plasma. Screen oxide 20 is etched in a dilute HF solution. The monitor wafer 30 is then annealed in an inert environment for about an hour at roughly 1100 degrees C. Sheet resistance is measured within the previousl patterned and open areas 40 using a four point probe technique which takes into account edge effects.

Ion implantation is commonly performed using patterned photoresist as an implantation mask. The implanted species accumulates in the photoresist resulting in a charging effect which tends to repel ions in the incoming beam.

Patterned photoresist, however, is not typically used as part of an ion implant sheet resistance monitor but rather a screen oxide monitor is subject to a blanket implant. By using the...