Laser terahertz emission microscope for inspecting electrical failures in integrated circuits
26 Jul 2004-pp 29-30
TL;DR: Experimental results on a biased 8-bit microprocessor, as well as unbiased MOSFETs embedded in a test element group (TEG) are reported.
Abstract: The inspection and fault analysis of semiconductor devices has become a critical issue with increasing demands for quality and reliability in circuits as stated in L. A. Krauss et al. (2001), K. Nikawa (2002) and K. Nikawa et al. (2003). Recently, we have developed a laser-terahertz (THz) emission microscope (LTEM) that can be applied for the noncontact and nondestructive inspection of the electrical faults in circuits presented in K. Nikawa et al. (2003). The LTEM can image the amplitude profile of the THz wave emitted by scanning the sample with femtosecond (fs) laser pulses. The amplitude of the THz emission generated by the transient photocurrent is proportional to the local electric field at the laser-irradiated area according to T. Kowa et al. (2003). Therefore, the LTEM image of the semiconductor device while it operates reflects the electric field distribution in the chip. By comparing the LTEM image of a damaged chip with that of a normal one, we can localize the electrical faults. In this work, we report experimental results on a biased 8-bit microprocessor, as well as unbiased MOSFETs embedded in a test element group (TEG).
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01 Oct 2007
TL;DR: While there are a number of challenges to be overcome there is little doubt that T-ray technology will play a significant role in the near future for advancement of security, public health, and defense.
Abstract: T-ray wavelengths are long enough to pass through dry, nonpolar objects opaque at visible wavelengths, but short enough to be manipulated by optical components to form an image. Sensing in this band potentially provides advantages in a number of areas of interest to security and defense such as screening of personnel for hidden objects and the retection of chemical and biological agents. Several private companies are developing smaller, reliable cheaper systems allowing for commercialization and this motivates us to review a number of promising applications within this paper. While there are a number of challenges to be overcome there is little doubt that T-ray technology will play a significant role in the near future for advancement of security, public health, and defense.
194 citations
TL;DR: The redesign and improved performance of the laser terahertz emission microscope (LTEM) is presented, which is a potential tool for locating electrical failures in integrated circuits and its application to examining of large-scale integration circuits is extended.
Abstract: We present the redesign and improved performance of the laser terahertz emission microscope (LTEM), which is a potential tool for locating electrical failures in integrated circuits. The LTEM produces an image of the THz waves emitted when the circuit is irradiated by a femtosecond laser; the amplitude of the THz emission is proportional to the local electric field. By redesigning the optical setup and improving the spatial resolution of the system to below 3 microm, we could extend its application to examining of large-scale integration circuits. As example we show the THz emission pattern of the electric field in an 8-bit microprocessor chip under bias voltage.
136 citations
TL;DR: In this paper, an overview of the field of terahertz-frequency electromagnetic waves, their properties and emerging applications is given; some widespread sources with their advantages and drawbacks are presented; an emphasis is placed on the parametric generation sources that we build and use in our research.
Abstract: An overview is given on the field of the terahertz-frequency electromagnetic waves, their properties and emerging applications. Some widespread sources with their advantages and drawbacks are presented; an emphasis is placed on the parametric generation sources that we build and use in our research. Several applications are then described: imaging techniques based on transmission, reflection and scattering, results in chemical imaging and electric field imaging, as well as linear scanning and the measurement of optical properties of highly-absorbing liquids.
107 citations
TL;DR: In this paper, a combination of a hemispherical solid immersion lens (SIL) and an LTEM with transmission-type detection mode was used for high-resolution imaging.
Abstract: A recently developed laser terahertz (THz) emission microscope (LTEM) is a new type of inspection tool for semiconductor integrated circuits by 2-D mapping of THz emission excited by femtosecond (fs) laser pulse. For high-resolution imaging, we demonstrate the combination of a hemispherical solid immersion lens (SIL) and an LTEM with transmission-type detection mode. Unlike reflective LTEM geometries, in which both the probing fs laser pulses and the generated THz emissions utilize the same optical components, the transmission system enables flexibility in the construction of both the fs laser and the THz detection optics: The optics on the incident side of the sample are used only to manipulate the fs pulses, while those on the transmission side are meant only for manipulating the THz emission. We could improve the spatial resolution by less than 1.5 mum by combining the objective lens with the hemispherical SIL with a refractive index n = 1.98 at 780 nm.
36 citations
Cites background or methods from "Laser terahertz emission microscope..."
...In the prototype LTEM [14], the spatial resolution was about 20 μm because a parabolic mirror with a hole between the objective lens and sample was used, as shown in Fig....
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...Recently, as a unique application, it demonstrated a new possibility for inspecting electrical faults in semiconductor integrated circuits and is, therefore, called the LTEM [14]....
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01 Jan 2008
TL;DR: The details of the LTEM systems and example applications for the evaluation of electric field distribution in integrated circuits and supercurrent distribution in high-temperature superconductors are introduced.
Abstract: Developments of laser terahertz (THz) emission microscope (LTEM) systems are reviewed. Femtosecond lasers can excite the THz wave emission from various electronic materials, such as semiconductors, high-temperature superconductors, manganites, multiferroic oxides, etc., due to ultrafast current modulation. Limiting the topic to semiconductors, the current modulation is realized by acceleration or deceleration of photoexcited carriers due to the local electric field extrinsically or intrinsically induced at the laser illumination spot. Thus, LTEM has a potential to visualize the local electric field distribution and photoresponse without any contacts or damages. We have ever constructed prototype free-space type and scanning fiber-probe (SFP) type LTEM systems with transmission or reflection mode. The system performance of the SFP-LTEM has been greatly improved compared with that for the prototype one. The spatial resolution of the SFP-LTEM system has a minimum spatial resolution less than 3 mum , which is defined by the laser beam diameter. The compact SFP-LTEM system, in particular the reflection system, has the potential to be utilized for wide applications as well as various materials. In this review paper, we introduce the details of the LTEM systems and example applications for the evaluation of electric field distribution in integrated circuits and supercurrent distribution in high-temperature superconductors.
31 citations
Cites background or methods from "Laser terahertz emission microscope..."
...94 tor) as the demonstration sample [ 29 ]. In the measure-...
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...After [ 29 ]. Fig. 3. LTEM images of the biased IC chip superimposed on optical...
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...This result shows 257 the possibility that LTEM can be utilized for the evaluation 258 of electronic circuits fabricated on semiconductor without 259 any contacts and damages [ 29 ]....
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...beam and (b) the voltage signal applied to Vin .A fter [ 29 ]....
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References
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Abstract: A laser terahertz-emission microscope (LTEM) system is proposed and developed for inspecting electrical faults in integrated circuits (IC). We test a commercial operational amplifier while the system is operating. Two-dimensional terahertz-emission images of the IC chip are clearly observed while the chip is scanned with a femtosecond laser. When one of the interconnection lines is cut, the damaged chip has a LTEM image different from that of normal chips. The results indicate that the LTEM system is a potential tool for IC inspection.
189 citations
TL;DR: The redesign and improved performance of the laser terahertz emission microscope (LTEM) is presented, which is a potential tool for locating electrical failures in integrated circuits and its application to examining of large-scale integration circuits is extended.
Abstract: We present the redesign and improved performance of the laser terahertz emission microscope (LTEM), which is a potential tool for locating electrical failures in integrated circuits. The LTEM produces an image of the THz waves emitted when the circuit is irradiated by a femtosecond laser; the amplitude of the THz emission is proportional to the local electric field. By redesigning the optical setup and improving the spatial resolution of the system to below 3 microm, we could extend its application to examining of large-scale integration circuits. As example we show the THz emission pattern of the electric field in an 8-bit microprocessor chip under bias voltage.
136 citations
02 Jun 1996
TL;DR: This work uses electric field singularities in metal-semiconductor microstructures to generate efficient THz radiation and electrical transients and reports on the generation process in a number of material systems.
Abstract: Summary form only given. Fast electrical transients and terahertz (THz) radiation are generated when biased coplanar striplines are excited within the gap by short laser pulses. This generation process is particularly efficient when the excitation is carried out close to the anode and has been observed in a number of material systems. In this work we go one step further and use electric field singularities in metal-semiconductor microstructures to generate efficient THz radiation and electrical transients.
102 citations
TL;DR: Recent developments in magnetic field imaging provide failure analysts with a tool to help overcome some of the hurdles involved in fault isolation of present and next generation semiconductor devices.
45 citations
TL;DR: In this paper, three new applications of a focused laser beam to VLSI interconnect diagnosis have been reported, in which interconnect heating by a laser beam and current change measurement are used.
22 citations