Magnetic Current Imaging of a TSV short in a 3D IC

2015 ◽  
Vol 2015 (DPC) ◽  
pp. 001408-001428
Author(s):  
Jan Gaudestad ◽  
Antonio Orozco
Keyword(s):  
Quantum Interference ◽  
Semiconductor Industry ◽  
Fault Isolation ◽  
Magnetic Current ◽  
Current Path ◽  
Fine Pitch ◽  
Dual Beam ◽  
Gmr Sensor ◽  
Test Chips ◽  
Chip Chip

In this paper we show Magnetic Field Imaging (MFI) is the best method for Electric Fault Isolation (EFI) of short failures in 2.5/3D Through Silicon Via (TSV) devices in a true non-destructive way by imaging the current path. To confirm the failing locations and to do Physical Failure Analysis (PFA), a Dual Beam-Plasma FIB (DB-PFIB) system was used for cross sectioning and volume analysis of the TSV structures and high resolution imaging of the identified defects. Magnetic Current Imaging (MCI) is a sub technique of MFI which has been used by the semiconductor industry for more than a decade to find electrical shorts and leakage paths and which has the capability to “look through” all materials typically used in the semiconductor industry, allowing global imaging without the need for physical de-processing [1, 2, 3]. MCI utilizes two types of sensors: a Superconducting Quantum Interference Device (SQUID) sensor for low current and large working distances and a Giant Magneto Resistance (GMR) sensor for sub micron resolution current imaging at wafer/die level [3]. The sample investigated in this work is a triple-layer stack, in which 2 layers of 50 μm thick test chip (Chip 1 and Chip 2 in Figure 1) were assembled on a 200 μm thick bottom chip (Chip 0 in Figure 1). The test chips were manufactured by imec's standard 65 nm CMOS Back End of Line (BEOL) process, 5×50 μm via-middle TSV technology [4], and fine pitch micro bumping process [6]. Further details of the test vehicle and assembly process can be found elsewhere [5]. The sample had a short between daisy chain a1 and a2, which were supposed to be electrically separated. The probe tests that was used for this experiment is shown in Table 1. The signal was injected into the respective daisy chains by probing V+ to V− on the bottom chip. To send a signal between daisy chain a1 and a2 one could probe V− to V− and V+ to V+. The MCI scans were done using the GMR sensor only. The sample was attached to a vacuum chuck and raster scanned. From Fig. 2 one can see that the current enters the top layer (Chip 2) at TSV 18 and goes back down again to Chip 1 at TSV 28. Since the sample clearly has multiple shorts, the short located at TSV pair 23 was chosen for PFA using the PFIB. A short is found between the 2 BEOL layers of Chip 1, causing the current to leak into Chip 2 (Fig. 3).

Advanced Non-Destructive Fault Isolation Techniques for PCB Substrates Using Magnetic Current Imaging and Terahertz Time Domain Reflectometry

2018 ◽  
Author(s):  
Daechul Choi ◽  
Yoonseong Kim ◽  
Jongyun Kim ◽  
Han Kim
Keyword(s):  
Time Domain ◽  
Quantum Interference ◽  
Flip Chip ◽  
Imaging System ◽  
Time Domain Reflectometry ◽  
Fault Isolation ◽  
Magnetic Current ◽  
Isolation Techniques ◽  
Super Conducting ◽  
Non Destructive

Abstract In this paper, we demonstrate cases for actual short and open failures in FCB (Flip Chip Bonding) substrates by using novel non-destructive techniques, known as SSM (Scanning Super-conducting Quantum Interference Device Microscopy) and Terahertz TDR (Time Domain Reflectometry) which is able to pinpoint failure locations. In addition, the defect location and accuracy is verified by a NIR (Near Infra-red) imaging system which is also one of the commonly used non-destructive failure analysis tools, and good agreement was made.

Magneto-Optical Frequency Mapping System for Very Low Resistance Short Circuit Failure Imaging

2015 ◽  
Author(s):  
Tomonori Nakamura
Keyword(s):  
Quantum Interference ◽  
Short Circuit ◽  
Ease Of Use ◽  
Lower Sensitivity ◽  
Imaging Method ◽  
Crystal Thickness ◽  
Low Resistance ◽  
Current Path ◽  
Gmr Sensor ◽  
Failure Localization

Abstract Magnetic field imaging (MFI) has been an excellent tool for a low resistance failure localization in LSI devices. A Superconducting Quantum Interference Device (SQUID) and a Giant Magneto Resistive (GMR) sensor are well known in this field. A SQUID has extremely high magnetic sensitivity (500 nA, <40 pT/ √Hz)[1], but the spatial resolution is somewhat problematic due to the clearance that is needed for cooling and vacuuming mechanism. A GMR sensor has higher resolution but lower sensitivity (50 uA, <10 nT/√Hz)[1] and, they have less flexibility because the sensor/stage has to be scanned during operation. In this paper, we present a new current imaging method called Magneto-Optical (MO) Frequency Mapping (MOFM). The imaging is based on a laser beam scanning, which allows flexibility and ease of use. The MO signal intensity is inversely proportional to the distance between the sensor and the current path to be detected. Since it can be 10 um or less, i.e., one half of the MO crystal thickness, it practically makes the MOFM’s system sensitivity is 10 uA, it only 20 times lower than a SQUID method, even though the intrinsic sensitivity may be about 250 times or so lower. It can also achieve high special resolution as with the GMR sensor because of the short distance or clearance needed to sense the current. These characteristics are verified with a TEG sample and we present a case in which it is applied for the short circuit failure localization.

Failure Analysis Work Flow for Electrical Shorts in Triple Stacked 3D TSV Daisy Chains

2015 ◽  
Vol 2015 (1) ◽  
pp. 000469-000473 ◽  
Author(s):  
J. Gaudestad ◽  
A. Orozco ◽  
I. De Wolf ◽  
T. Wang ◽  
T. Webers ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Fault Isolation ◽  
Root Cause ◽  
Current Path ◽  
Dual Beam ◽  
Resolution Imaging ◽  
Magnetic Field Imaging ◽  
Non Destructive

In this paper we show an efficient workflow that combines Magnetic Field Imaging (MFI) and Dual Beam Plasma Focused Ion Beam (DB-PFIB) for fast and efficient Fault Isolation and root cause analysis in 2.5/3D devices. The work proves MFI is the best method for Electric Fault Isolation (EFI) of short failures in 2.5/3D Through Silicon Via (TSV) triple stacked devices in a true non-destructive way by imaging the current path. To confirm the failing locations and to do Physical Failure Analysis (PFA), a DB-PFIB system was used for cross sectioning and volume analysis of the TSV structures and high resolution imaging of the identified defects. With a DB-PFIB, the fault is exposed and analyzed without any sample prep artifacts seen in mechanical polishing or laser preparation techniques and done in a considerably shorter amount of time than that required when using a traditional Gallium Focused Ion Beam (FIB).

Magnetic Field Imaging for 3D applications

2014 ◽  
Vol 2014 (DPC) ◽  
pp. 001937-001965
Author(s):  
Jan Gaudestad ◽  
Antonio Orozco
Keyword(s):  
Magnetic Field ◽  
Field Distribution ◽  
Quantum Interference ◽  
Device Fabrication ◽  
Fault Isolation ◽  
Current Path ◽  
Magnetic Field Imaging ◽  
The Magnetic Field ◽  
Field Imaging ◽  
A Current

The challenges that 3D integration present to Failure Analysis require the development of new Fault Isolation techniques that allows for non-destructive, true 3D failure localization. By injecting a current in the device under test (DUT), the current generates a magnetic field around it and this magnetic field is detected by a sensor above the device. Magnetic field imaging (MFI) is a natural candidate for 3D Fault Isolation of complex 3D interconnected devices. This is because the magnetic field generated by the currents in the DUT passes unaffected through all materials used in device fabrication; the presence of multiple metal layers, dies or other opaque layers do not have any impact on the magnetic field signal. The limitations of the technique are not affected by the number of layers in the stacked devise in samples such as wirebonded stacked memory, Through Silicon Via (TSV) stacked die or even package on package (PoP). The sample is raster scanned and magnetic field is acquired at determined steps providing a magnetic image of the field distribution. This magnetic field data is typically processed using a standard inversion technique to obtain a current density map of the device. The resulting current map can then be compared to a circuit diagram, an optical or infrared image, or a non-failing part to determine the fault location. Today, giant-magnetoresistive (GMR) sensors have been added to the Superconducting Quantum Interference Device (SQUID) sensor to allow higher resolution and Fault Isolation (FI) I at die level. Magnetic Field Imaging (MFI), using SQUID as the high sensitive magnetic sensor in combination with a high resolution GMR sensor. A solver algorithm capable of successfully reconstructing a 3D current path based on an acquired magnetic field image from both sensors has been developed. The generic 3D inverse problem has no unique solution. Given a particular 3D magnetic field distribution, there are an infinite number of current path distributions that will result in such magnetic field. This ill-posed problem has restricted, so far, the use of magnetic imaging to 2D. A different kind of 3D solver can be constructed, nevertheless capable of obtaining a single solution. The 3D solver algorithm is not only capable of extracting the 3D current path, but it also provides valuable geometrical information about the device. Accurately being able to position each current segment in a layer allows the FA engineer to follow the current as it vertically moves from one die (or layer) to another. [1,2,3]

Construction of a 3-D Current Path Using Magnetic Current Imaging

2007 ◽  
Author(s):  
Frederick Felt ◽  
Lee Knauss ◽  
Anders Gilbertson ◽  
Antonio Orozco
Keyword(s):  
Three Dimensional ◽  
Form Factors ◽  
Fault Isolation ◽  
Magnetic Sensors ◽  
Physical Analysis ◽  
Magnetic Current ◽  
Nasa Goddard Space ◽  
Current Path ◽  
Multiple Devices ◽  
Board Level

Abstract The need to miniaturize in the electronics industry is driving smaller form factors, and resulting in complex packaging innovations such as structures with multiple devices stacked inside a three dimensional package. These structures present a challenge for non-destructive fault isolation. Two such modules recently exhibited failures on the NASA Goddard Space Flight Center Solar Dynamic Observatory (SDO) during board-level testing. Each module consisted of eight vertically-stacked mini-boards, each mini-board with a single EEPROM microcircuit and capacitor, and connected by external gold metallization to module pins. Both failed modules exhibited low-resistance shorts between multiple pins. The orthogonal structure of the module prompted the use of magnetic current imaging (MCI) in three planes in order to construct an internal three-dimensional current path for each of the failed modules. Magnetic current imaging is able to “look through” non-magnetic, or de-gaussed packaging materials, allowing global imaging without physical deprocessing of the stacked EEPROM modules, in order to construct the internal current path and localize defects. To our knowledge, this is the first time that this has been done. Following global isolation of the defects, two types of magnetic sensors were used in parallel with limited deprocessing in order to more precisely characterize suspect failure locations before actually physically exposing the defects. This paper will show the process for using magnetic current imaging with both SQUID and magnetoresistive (GMR) sensors to isolate defects in two stacked EEPROM packages along with the final physical analysis of the defects. The failure analysis found that these devices were damaged by external heat, possibly during oven pre-conditioning or hot air soldering onto the board. The manufacturer, 3-D Plus, was not implicated in the failure.

Analysis of a Microcircuit Failure using SQUID and MR Current Imaging

2005 ◽  
Author(s):  
Frederick S. Felt
Keyword(s):  
Integrated Circuits ◽  
Thermal Emission ◽  
High Current Density ◽  
Fault Isolation ◽  
Magnetic Sensors ◽  
Nand Gate ◽  
Magnetic Current ◽  
Package Design ◽  
Low Resistance ◽  
Current Path

Abstract SQUID and MR magnetic sensors have separately been used for fault isolation of shorts and resistive opens in integrated circuits and packages. These two technologies were once considered to be mutually exclusive, although recent studies [1] rather pointed to their complementary character. This paper shows, for the first time, the use of these two sensors together to isolate a low resistance short in a Quad-NAND gate microcircuit. Electrical test confirmed low resistance shorts between three of the device pins. However, internal optical inspection found no evidence of failure. The low resistance of the shorts was deemed insufficient for liquid crystal analysis. Magnetic current imaging with a SQUID sensor confirmed current flow through the package lead frame and isolated the defect to the microcircuit. Due to package design and the resulting distance of the scan plane, the SQUID was unable to resolve the current path on the microcircuit. In parallel with the SQUID, a magnetoresistive (MR) probe was employed to fit inside the device cavity, make direct contact with the microcircuit, and map high-resolution current images. Two sites with high-current density were accurately identified by MCI in input transistors. Subsequent deprocessing revealed that the defects were located under a broad sheet of aluminum metallization which blocked optical detection, and rendered detection by thermal emission difficult.

Open Failure Localization by Using MOFM—Magneto-Optical Frequency Mapping System with 532 nm Light Source

2017 ◽  
Author(s):  
Tomonori Nakamura ◽  
Akihiro Otaka
Keyword(s):  
Magnetic Field ◽  
Light Source ◽  
Quantum Interference ◽  
Modulation Frequency ◽  
Optical Frequency ◽  
Weak Current ◽  
Magnetic Current ◽  
Current Path ◽  
Ac Current ◽  
The Magnetic Field

Abstract Magnetic current imaging (MCI) is an effective method for the isolation of individual integrated circuit (IC) current paths [1]. MCI is therefore useful in localizing open/short defects. In the case of a short, the failure current must be large enough to enable the detection of the magnetic field; however, in the case of the open failure, the current is very weak and detection can be limited by the wiring capacitance and modulation frequency. Often, magnetic sensor sensitivity is a function of the sensor size. Superconducting Quantum Interference Device (SQUID) sensors can detect weak current in an open failure, but the resolution is limited by the sensor size and can be difficult to utilize for IC applications. A Giant Magnetic Resistance (GMR) sensor has enough resolution [2], but cannot achieve enough sensitivity till now. This paper will present the use of Magneto-Optical Frequency Mapping (MOFM) using a 532nm light source. In addition, this paper will describe a specific IC application for an open failure measurement. For this technique, the MO crystal (sensor material) is placed directly on the DUT (a wiring test sample). This paper will demonstrate that the magnetic field modulation from AC current in open wirings can be detected. In addition, the details of the AC current path can be visualized using a Magneto-Optical based MCI measurement. Finally, the open point in the failing circuit will be shown to be isolated with an accuracy of a few tens of micrometers.

Failure Analysis Work Flow for Electrical Shorts in Triple Stacked 3D TSV Daisy Chains

2014 ◽  
Author(s):  
J. Gaudestad ◽  
A. Orozco ◽  
I. De Wolf ◽  
T. Wang ◽  
T. Webers ◽  
...  
Keyword(s):  
Failure Analysis ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Fault Isolation ◽  
Root Cause ◽  
Current Path ◽  
Dual Beam ◽  
Resolution Imaging ◽  
Magnetic Field Imaging ◽  
Non Destructive

Abstract In this paper we show an efficient workflow that combines Magnetic Field Imaging (MFI) and Dual Beam Plasma Focused Ion Beam (DB-PFIB) for fast and efficient Fault Isolation and root cause analysis in 2.5/3D devices. The work proves MFI is the best method for Electric Fault Isolation (EFI) of short failures in 2.5/3D Through Silicon Via (TSV) triple stacked devices in a true non-destructive way by imaging the current path. To confirm the failing locations and to do Physical Failure Analysis (PFA), a DB-PFIB system was used for cross sectioning and volume analysis of the TSV structures and high resolution imaging of the identified defects. With a DB-PFIB, the fault is exposed and analyzed without any sample prep artifacts seen in mechanical polishing or laser preparation techniques and done in a considerably shorter amount of time than that required when using a traditional Gallium Focused Ion Beam (FIB).

Thin-Die Flip Chip Physical-FA Process Flow

2002 ◽  
Author(s):  
Andrew J. Komrowski ◽  
N. S. Somcio ◽  
Daniel J. D. Sullivan ◽  
Charles R. Silvis ◽  
Luis Curiel ◽  
...  
Keyword(s):  
Sample Preparation ◽  
Failure Analysis ◽  
Flip Chip ◽  
Semiconductor Industry ◽  
Organic Substrate ◽  
Fault Isolation ◽  
Preparation Methods ◽  
Chip Technology ◽  
Isolation Test ◽  
Sample Preparation Methods

Abstract The use of flip chip technology inside component packaging, so called flip chip in package (FCIP), is an increasingly common package type in the semiconductor industry because of high pin-counts, performance and reliability. Sample preparation methods and flows which enable physical failure analysis (PFA) of FCIP are thus in demand to characterize defects in die with these package types. As interconnect metallization schemes become more dense and complex, access to the backside silicon of a functional device also becomes important for fault isolation test purposes. To address these requirements, a detailed PFA flow is described which chronicles the sample preparation methods necessary to isolate a physical defect in the die of an organic-substrate FCIP.

High-Resolution Backside GMR Magnetic Current Imaging on a Contour-Milled Globally Ultrathin Die

2014 ◽  
Author(s):  
D. Vallett ◽  
J. Gaudestad ◽  
C. Richardson
Keyword(s):  
Quantum Interference ◽  
Flip Chip ◽  
Milling Process ◽  
Dramatic Improvement ◽  
Superconducting Quantum Interference Device ◽  
Density Peak ◽  
Magnetic Current ◽  
Gmr Sensors ◽  
Silicon Thickness ◽  
A Current

Abstract Magnetic current imaging (MCI) using superconducting quantum interference device (SQUID) and giant-magnetoresistive (GMR) sensors is an effective method for localizing defects and current paths [1]. The spatial resolution (and sensitivity) of MCI is improved significantly when the sensor is as close as possible to the current paths and associated magnetic fields of interest. This is accomplished in part by nondestructive removal of any intervening passive layers (e.g. silicon) in the sample. This paper will present a die backside contour-milling process resulting in an edge-to-edge remaining silicon thickness (RST) of < 5 microns, followed by a backside GMR-based MCI measurement performed directly on the ultra-thin silicon surface. The dramatic improvement in resolving current paths in an ESD protect circuit is shown as is nanometer scale resolution of a current density peak due to a power supply shortcircuit defect at the edge of a flip-chip packaged die.

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