Proc. SPIE. 9424, Metrology, Inspection, and Process Control for Microlithography XXIX
KEYWORDS: Metrology, Etching, Data processing, Process control, Critical dimension metrology, Reactive ion etching, Algorithm development, Data communications, Semiconducting wafers, Fin field effect transitor
Hybrid metrology (HM) is the practice of combining measurements from multiple toolset types in order to enable or improve metrology for advanced structures. HM is implemented in two phases: Phase-1 includes readiness of the infrastructure to transfer processed data from the first toolset to the second. Phase-2 infrastructure allows simultaneous transfer and optimization of raw data between toolsets such as spectra, images, traces – co-optimization. We discuss the extension of Phase-1 to include direct high-bandwidth communication between toolsets using a hybrid server, enabling seamless fab deployment and further laying the groundwork for Phase-2 high volume manufacturing (HVM) implementation. An example of the communication protocol shows the information that can be used by the hybrid server, differentiating its capabilities from that of a host-based approach. We demonstrate qualification and production implementation of the hybrid server approach using CD-SEM and OCD toolsets for complex 20nm and 14nm applications. Finally we discuss the roadmap for Phase-2 HM implementation through use of the hybrid server.
Metrology of line-edge roughness (LER) or line-width roughness (LWR) reduced less than a few nanometers in recent advanced-process is one of issues because measured LER is strongly dependent on measurement conditions such as magnification and beam dose. It may happen that different organizations measure different LERs on an identical sample. By using an ultra-low LER sample we demonstrate intolerable change of measured LER between with and without necessary key-points in the measurement conditions of critical-dimension secondary electron microscope (CD-SEM).
The accelerated pace of the semiconductor industry in recent years is putting a strain on existing dimensional metrology
equipments (such as CDSEM, AFM, Scatterometry) to keep up with ever-increasing metrology challenges. However, a
revolution appears to be forming with the recent advent of Hybrid Metrology (HM) - a practice of combining
measurements from multiple equipment types in order to enable or improve measurement performance. In this paper we
extend our previous work on HM to measure advanced 1X node layers - EUV and Negative Tone Develop (NTD) resist
as well as 3D etch structures such as FinFETs. We study the issue of data quality and matching between toolsets
involved in hybridization, and propose a unique optimization methodology to overcome these effects. We demonstrate
measurement improvement for these advanced structures using HM by verifying the data with reference tools (AFM,
XSEM, TEM). We also study enhanced OCD models for litho structures by modeling Line-edge roughness (LER) and
validate its impact on profile accuracy. Finally, we investigate hybrid calibration of CDSEM to measure in-die resist line
height by Pattern Top Roughness (PTR) methodology.
Measurement uncertainty requirement 0.37 nm has been set for the Critical Dimension (CD) metrology tool in 32 nm
technology generation, according to the ITRS. The continual development in the fundamental performance of Critical
Dimension Scanning Electron Microscope (CD-SEM) is essential, as in the past, and for this generation, a highly precise
tool management technology that monitors and corrects the tool-to-tool CD matching will also be indispensable.
The potential factor that strongly influences tool-to-tool matching is the slight difference in the electron beam
resolution, and its determination by visual confirmation is not possible from the SEM images. Thus, a method for
quantitative evaluation of the resolution variation was investigated and Profile Gradient (PG) method was developed. In
its development, considerations were given to its sensitivity against CD variation and its data sampling efficiency to
achieve a sufficient precision, speed and practicality for a monitoring function that would be applicable to mass
semiconductor production line. The evaluation of image sharpness difference was confirmed using this method.
Furthermore, regarding the CD matching management requirements, this method has high sensitivity against CD
variation and is anticipated as a realistic monitoring method that is more practical than monitoring the actual CD
variation in mass semiconductor production line.