Non-contact Corona-Kelvin based Metrology for High-k Dielectric Characterization with an Extension to Micro-Scale Measur
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0917-E09-01
Non-contact Corona-Kelvin based Metrology for High-k Dielectric Characterization with an Extension to Micro-Scale Measurement Marshall Wilson, Dmitriy Marinskiy, Carlos Almeida, Joseph N. Kochey, Anton Byelyayev, Alexandre Savtchouk, John D'Amico, Andrew Findlay, Lubek Jastrzebski, and Jacek Lagowski Semiconductor Diagnostics Inc., 3650 Spectrum Boulevard, Suite 130, Tampa, FL, 33612
ABSTRACT In-line monitoring of the electrical properties of high-k dielectrics in logic or memory fab-lines has become increasingly important in the semiconductor industry. Non-contact coronaKelvin based metrology can be used to affectively monitor in-line key dielectric properties. Furthermore, we present an important extension of this metrology to the micro-scale that allows measurement of dielectric properties on test sites as small as 40µm x 70µm. This is achieved through miniaturization of the corona charging apparatus and of the Kelvin probe without a sacrifice in precision or repeatability. Corona-Kelvin micro-metrology allows for the monitoring of the critical dielectric properties directly on product wafers that can then be returned to the fabline for continued processing. Application examples are given for dielectric capacitance of advanced dielectrics and for the properties of an oxide-nitride-oxide (ONO) memory structure. In the latter case we demonstrate programming and erasing of the ONO structure realized by corona charging. We also use the measured flatband voltage and total charge to identify the location of the programmed charge at the first SiO2/Si3N4 interface in the ONO structure. INTRODUCTION There are two primary ways in which dielectrics are electrically characterized in a modern IC fab-line. The first way involves the use monitor wafers which are removed at various points in the line and measured. The monitor wafers are then recycled or discarded. The second approach involves measuring the actual patterned product wafer by probing in designated test sites typically located in the scribe lines. The product wafer can then be returned to the process at the point at which it was removed. In current technology nodes, these test sites could be as small as 40µm x 70µm. Non-contact electrical characterization techniques are routinely used to monitor dielectric charge, leakage and capacitance (among other properties) in fab-lines as a replacement for conventional MOS-type diagnostics [1-5]. Historically these techniques have used monitor wafers rather than product wafers due to an inability to measure on miniature test sites. For typical corona-Kelvin based non-contact electrical characterization techniques the probing diameter is on the order of a few millimeters, i.e. it exceeds by about two orders of magnitude the dimensions of the miniature test sites on product wafers. A recent breakthrough in the miniaturization of the corona-Kelvin metrology has enabled the non-contact electrical characterization of dielectrics in test sites on product wafers [6,7]. This transition to micro-scale measurements was ach
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