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Air Cavity Silicide Block of Extended Drain MOS for High Voltage Application

IP.com Disclosure Number: IPCOM000200127D
Publication Date: 2010-Sep-29
Document File: 4 page(s) / 40K

Publishing Venue

The IP.com Prior Art Database

Abstract

For extended drain MOS strucutre used in High Voltage ICs, charge trapping within the OP nitride and along interface could cause device Vt degradation, therefore impacts device reliability and performance. Complete elimination of such OP nitride layer could benefit both device reliability and performance. In this article, a novel device structure and process method regarding creation an air cavity above LDD region as silicide block to replace convetional OP nitride is discussed. Introduction of such airgap above LDD could reduce device capacitive coupling and charging impact. Therefore it could result in significant device performance and reliability improments.

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Air Cavity Silicide Block of Extended Drain MOS for High Voltage Application

Disclosed is a method and system for fabricating an extended drain MOS structure with improved performance and reliability for high voltage applications. Figures 1-4 illustrates steps taken for fabricating the MOS with air cavity over extended Drain region.

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Figure 1

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Figure 2

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Figure 3

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Figure

As illustrated in Figure 1, thermally decomposed polymer layer is formed above the extended drain region of a MOS device by CVD or PVD deposition. Subsequently, a thin SiN layer is deposited on top of polymer layer using the same mask as shown in Figure 2. Thereafter, at step 2, a 250C-400C anneal of certain time is performed to thermally decompose polymer, and therefore to form air gap/cavity above extended Drain region as shown in Figure 3. Subsequently, silicide could be formed on top of silicon as shown in Figure 4 of pink boxes.

This air cavity OP process can avoid charging induced Vth shift during device operation, and also could reduce capacitive coupling between CA bar and LDD region to improve device performance. Polymer serves as a space holder to form air gap layer, and it is a low thermal process. Thus, the method an...