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USE OF STREAK CAMERA FOR PICOSECOND EMISSION MICROSCOPY AND APPLICATIONS FOR FAILURE ANALYSIS OF INTEGRATED CIRCUITS

IP.com Disclosure Number: IPCOM000008906D
Original Publication Date: 1999-Jan-01
Included in the Prior Art Database: 2002-Jul-23
Document File: 2 page(s) / 128K

Publishing Venue

Motorola

Related People

Stefan Zollner: AUTHOR

Abstract

The testing of CMOS circuits with high spatial and timing resolution can be achieved using picosecond emission microscopy based on a microchannel plate photomultiplier tube with a posi- tion-sensitive anode and time-correlated photon counting, but the time resolution is limited to about 10 GHz. The time resolution can be improved to about 1000 GHz through the use of a streak camera. If an infrared-sensitive streak camera (Sl spectral response or equivalent) is used, this may also reduce the need for backthinning the substrate of the circuit.

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MO-LA Technical Developments

USE OF STREAK CAMERA FOR PlCOSECONb EMISSION MICROSCOPY AND APPLICATIONS FOR hAlLURE

ANALYSIS OF INTEGRATED ClRCUiTS

by Stefan Zollner

ABSTRACT

  The testing of CMOS circuits with high spatial and timing resolution can be achieved using picosecond emission microscopy based on a microchannel plate photomultiplier tube with a posi- tion-sensitive anode and time-correlated photon counting, but the time resolution is limited to about 10 GHz. The time resolution can be improved to about 1000 GHz through the use of a streak camera. If an infrared-sensitive streak camera (Sl spectral response or equivalent) is used, this may also reduce the need for backthinning the substrate of the circuit.

BACKGROUND

  In order to analyze the performance of integrat- ed circuits (particularly logic chips) and for failure analysis, a variety of techniques are currently used: Thermal liquid crystal imaging (or scanning thermal microscopy) can look for hot spots on the chips. Special circuitry (such as ZDDQ control inputs) is added primarily for failure analysis (without enhancing the performance of the device). One of the most powerful techniques is the detection of light emission from the circuit (emission microscopy). Each individual CMOS transistor emits light in the form of black-body radiation from the hot electrons in the channel, which can be detected using a high-magnification optical micro- scope. (The emission from hot holes in p-MOSFETs is weaker.) Until recently, timing issues could not be studied with emission microscopy, since CW detec- tion using a slow CCD camera was used. For timing issues, electron beam testers were used, but their use becomes increasingly difficult because of shrinking device length scales, flip-chip packaging, and many layers of metallization.

PROBLEM

  Recently, analysis using time-resolved emission microscopy through the use of a microchannel plate (MCP) photomultiplier tube (PMT) with position- sensitive anode (PSA), along with time-correlated photon counting (including a constant-fraction dis- criminator and a time-to-pulse height converter) and massive signal averaging has been demonstrated. The use of a MCP has the advantage of a fast response time because :'of the short transit time spread (TTS). The technique allows the compilation of "movies" displaying the switching of the individ- ual n-MOSFETs in the circuit with great magnifica- tion in both space and time. (The image is magnified by the microscope and the switching is slowed down by signal averaging with ,the MCP-PSA, each frame in the movie corresponding to about 100 ps.) By adding a beam splitter to the optical beam path in the microscope, both detectors (CCD and MCP- PSA) can be used simultaneously.

  This technique, although revolutionary, has the following disadvantages: (i) The limit in the time resolution is 100 ps, therefore the switching of tran- sistors at a rate faster than 10 GHz cannot be stud- ied. Since the technology...