Fast and accurate scatterometry metrology method for STI CMP step height process evaluation

Abstract

At the 28nm node using 300mm wafers, oxide step height in STI CMP transient gate after-etch inspection (TG AEI) wafers is a critical parameter that affects device performance and should be monitored and controlled. For production process control of this kind of structure, a metrology tool must utilize a non-destructive measurement technique, and have high sensitivity, precision and throughput [1]. This paper discusses a scatterometry-based measurement method for monitoring critical dimension step height in STI CMP instead of traditional measurement methods such as atomic force microscopy (AFM). The scatterometry tool we used for our investigations was the KLA-Tencor SpectraShape 8810, which is the most recent model of the spectroscopic critical dimension (SCD) metrology tools that have been implemented in production for process control of TG AEI structures. AFM was used as a reference metrology technique to assess the accuracy performance of the SpectraShape8810. The first objective of this paper is to discuss the best azimuth angle and floating parameters for scatterometry measurement of the step height feature in TG AEI wafers. Second, this paper describes the tool matching performance of SpectraShape 8810 and correlation to AFM determined using a DOE of TG AEI wafers.

Features of control of silicon nanostructures technology

“…I n t he pr ac t ice of mo der n microelectronics, optical scatterometry is used as a standard method for controlling the formation of three-dimensional structures. In particular, scatterometry is actively used to control critical dimensions in photolithographic [18] and etching processes [17,19]. This technique allows one to analyze diffraction patterns from periodic structures in order to restore their spatial profiles.…”

“…В мировой практике современной мик роэ ле к т р он и к и оп т и че с к а я с к ат т е р оме т ри я используется в качестве стандартного метода к он т р о л я п р оц е с с ов ф о рм и р ов а н и я т р е хмерных ст рукту р. В частности, скаттеромет ри я а к т и вно п ри ме н яе т с я д л я кон т р ол я the world practice, the scatterometry has become widely used in the transition to small design rules [19,21], since it allows the replacement of several traditional means of control, and also has high performance and accuracy [20]. The technique is successfully applied at technological levels up to 20 nm [20,21], and the effect of the roughness of the element boundaries on the result has been studied [18,22] and can be taken into account.…”

“…Further shift of the spectral range of optical scatterometers is problematic, since it will require vacuumation of the optical path, the use of ultrapure nitrogen for its constant purging, or other technical solutions that will lead to a sharp increase in the cost of the equipment and the cost of its operation. Therefore, leading world manufacturers of metrological equipment are developing критических размеров в фотолитографических процессах [18] и процессах травления [17,19]. Эта методика позволяет ана лизировать картины дифракции от периодических структур с целью восстановления их пространственных профилей.…”

“…При этом возможно не только измерение латеральных размеров периодических структур, но одновременно и глубины канавок травления, наклона их стенок. В мировой практике скаттерометрия получила широкое распространение при переходе на малые топологические нормы [19,21], так как позволяет заменить сразу несколько тра диционных средств контроля, а так же обла дает высокой производительностью и точностью [20]. Методика успешно применяется на технологических уровнях вплоть до 20 нм [20,21], причем влияние шероховатостей границ элементов на результат изучено [18,22] и может быть учтено.…”

Scatterometry measurement for SiGe AEI sigma-shaped gate structures of 28nm technology

“…Furthermore, scatterometry is an established, non-destructive metrology technique with proven performance for traditional gate process control. The development of additional optical technologies and modeling capabilities has extended scatterometry's measurement capability to today's more complex device structures on a broad range of process layers [2,3,4,5]. In particular, a newgeneration scatterometry tool, KLA-Tencor's SpectraShape 8810 using AcuShape2 modeling software, includes several enhanced and new optical technologies and advanced modeling capabilities [6,7] that provide the sensitivity required for production process control of complex structures for advanced design node devices.…”