This paper describes a novel flow using analog simulations for the failure analysis of digital, analog, and mixed signal devices. Although cell level diagnosis tools are available in the industry, it presents a solution through analog intra-cell simulation particularly advantageous when multiple defects give the same fault result at cell level. Details of case studies such as the one analog intracell simulation on digital device and the analog laser voltage probing are covered. The aim of the simulation solution proposed is to support the failure analyst to interpret emission images on analog devices. The presented analog simulation flow consists of computing the current (or current density) in MOS and bipolar transistors and simulating the internal waveforms in digital or analog cells. It enables failure analysts to interpret light emission and laser voltage probing results obtained on a physical device in a fast and efficient way.

By adding a transmission grating into the optical path of our photon emission system and after calibration, we have completed several failure analysis case studies. In some cases, additional information on the emission sites is provided, as well as understanding of the behavior of transistors that are associated to the fail site. The main application of the setup is used for finding and differentiating easily related emission spots without advance knowledge in light emission mechanisms in integrated circuits.

The Laser Voltage Imaging (LVI) technique, introduced in 2007 [1][2], has been demonstrated as a successful defect localization technique to address problems on advanced technologies. In this paper, several 28nm case studies are described on which the LVI technique and its derivatives provide a real added value to the defect localization part of the Failure Analysis flow. We will show that LVI images can be used as a great reference to improve the CAD alignment overlay accuracy which is critical for advanced technology debug. Then, we will introduce several case studies on 28nm technology on which Thermal Frequency Imaging (TFI) and Second Harmonic Detection (two LVI derivative techniques) allow efficient defect localization.

The Laser Voltage Imaging (LVI) technique [1], introduced in 2009, appears as a very promising approach for Failure Analysis application which allows mapping frequencies through the backside of integrated circuits. In this paper, we propose a new range of application based on the study of the LVI second harmonic for signal degradation analysis. After a theoretical study of the impact of signal degradation on the second harmonic, we will demonstrate the interest of this new approach on two case studies on ultimate technology (28nm). This technique is a new approach of failure analysis that maps timing degradation and duty cycle degradation. In order to confirm the degradations we will use the LVP Technique. The last part is two real case studies on which this LVI second harmonic technique was used to find the root cause of a 28nm process issue.

In semiconductor industries, development of new technologies and new products generally follows a phase of yield improvement where Failure Analysis expertise is used to locate and fix killer defects and for design debug. When process and design reach a certain level of maturity, a second phase of optimization, qualification and reliability is executed in which Failure Analysis expertise is used for internal timing characterization of integrated circuit and results are compared with design/process simulations. In order to reduce the cost of testing during manufacturing, circuits embed Built in Self Timing Characterizer (BISC) for timing measurements inside critical functional blocks. Thanks to advanced integration, the last CMOS technologies allow high performance in terms of speed. Arithmetic and Logical Units (ALU) are able to work at frequencies greater than few GHz and some memories’ access time is lower than hundreds picoseconds. In the CMOS 40nm analysis case study presented in this paper, a BISC measurement of memories’ access times gives different results than what was expected from simulation. Internal probing becomes mandatory to understand this critical timing issue. A complete comparison is done between the 3 contactless probing techniques available in our laboratory which are the E-Beam Testing (EBT), Time Resolved Emission (TRE) and the recent Laser Voltage Probing (LVP) to highlight strength and weakness of each probing techniques in front of this timing related defect. We demonstrate that the LVP is an inevitable technique to address the nanometer-scale technologies in terms of spatial resolution, low voltage measurements and timing performance.

For Very Deep submicron Technologies, techniques based on the analysis of reflected laser beam properties are widely used. The Laser Voltage Imaging (LVI) technique, introduced in 2009, allows mapping frequencies through the backside of integrated circuit. In this paper, we propose a new technique based on the LVI technique to debug a scan chain related issue. We describe the method to use LVI, usually dedicated to frequency mapping of digital active parts, in a way that enables localization of resistive leakage. Origin of this signal is investigated on a 40nm case study. This signal can be properly understood when two different effects, charge carrier density variations (LVI) and thermo reflectance effect (Thermal Frequency Imaging, TFI), are taken into account.