EP0180780A1
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Noncontact dynamic tester for integrated circuits
Assignee: International Business Machines Corp
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Filing: 1985-10-04
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Granted: —
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Expires: 2005-10-04
Abstract
Abstract Testing of integrated circuit process intermediates, such as wafers, dice or chips in various stages of production (test chip) is facilitated by a nonintrusive, noncontact dynamic testing technique, using a pulsed laser 7, with laser light modification 8 to increase photon energy through conversion to shorter wavelength. The high energy laser light excites electron emissions to pass to the detection system 13, 14 as a composite function of applied light energy and of dynamic operation of the circuit; detecting those emissions by an adjacent detector requires no ohmic contacts or special circuitry on the integrated circuit chip or wafer. Photoelectron energy 10 emitted from a test pad 3 on the test chip 1 is detected as a composite function of the instantaneous input voltage as processed on the test chip, in dynamic operation including improper operation due to fault. The pulse from the 'laser, as modified through light modification, the parameters of detection of bias voltages, and the distances involved in chip-grid-detector juxtaposition, provides emissions for detection of circuit voltages occuring on the test chip under dynamic conditions simulating actual or stressed operation, with high time resolution of the voltages and their changes on the circuit.
Inventors
- 👤 Johannes Georg Beha
- 👤 Russell Warren Dreyfus
- 👤 Gary Wayne Rubloff
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-29 21:43
CPC Classifications
G; G01; G01R; G01R31/00; G01R31/28; G01R31/302; G01R31/308
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
229 words
A system for dynamic testing of integrated circuit process intermediates characterized by (a) mounting means(2), including a vacuum chamber (4) with a test chip site for mounting a test chip (1) both electronically exercisable and accessible by radiation; (b) pulsed laser means (7), providing a sharply focussed, very short duration pulse of light, of controlled wavelength sufficiently short to cause emission of photoelectrons and resulting secondary electrons, to selected positions on a test chip mounted in said test chip site; and (c) laser modufication means (8), connected to said pulsed taser means, effective to modify laser light from said pulsed laser means to provide laser photon energy equal to or greater than 4.2 eV; (d) detector bias means (11, 12) and cooperating detection means (13, 14) juxtaposed to said mounting means adjacent said test chip site; whereby photoelectron energy emitted from a test pad on the test chip is detected as a composite function of the instantaneous input voltage as processed on the test chip, including proper operation and also including improper operation due to fault, the parameters of the pulse from said laser modification means (8), the parameters of bias voltages on said detector bias means and the distances involved in test chip-detector bias means-detection means juxtaposition, thus providing detection of circuit voltages occuring on the test chip under dynamic conditions simulating conditions of actual or stressed operation.
Claim 2
Independent Claim
229 words
A system for dynamic testing of integrated circuit process intermediates characterized by (a) mounting means(2), including a vacuum chamber (4) with a test chip site for mounting a test chip (1) both electronically exercisable and accessible by radiation; (b) pulsed laser means (7), providing a sharply focussed, very short duration pulse of light, of controlled wavelength sufficiently short to cause emission of photoelectrons and resulting secondary electrons, to selected positions on a test chip mounted in said test chip site; and (c) laser modufication means (8), connected to said pulsed taser means, effective to modify laser light from said pulsed laser means to provide laser photon energy equal to or greater than 4.2 eV; (d) detector bias means (11, 12) and cooperating detection means (13, 14) juxtaposed to said mounting means adjacent said test chip site; whereby photoelectron energy emitted from a test pad on the test chip is detected as a composite function of the instantaneous input voltage as processed on the test chip, including proper operation and also including improper operation due to fault, the parameters of the pulse from said laser modification means (8), the parameters of bias voltages on said detector bias means and the distances involved in test chip-detector bias means-detection means juxtaposition, thus providing detection of circuit voltages occuring on the test chip under dynamic conditions simulating conditions of actual or stressed operation.
Claim 3
Dependent Claim
58 words
A system for dynamic testing of integrated circuit process intermediates according to claim 1 characterized in that said laser modification means (8) comprises fundamental frequency generating means (16, 17), second harmonic generating means (22), and third harmonic generating means (23), all in tandem, or alternative means. effective to modify laser light to high electron energy at decreased wavelength.
Claim 4
Dependent Claim
40 words
A system for dynamic testing of integrated circuit process intermediates according to claim 1 characterized in that said detection means comprises a bandpass electron energy analyzer (13) to detect only electrons with energies lying within a limited range of values.
Claim 5
Dependent Claim
63 words
A system for dynamic testing of integrated circuit process intermediates according to claim 1 characterized in that said detector bias means provides a retarding electric field to said detection means, through which field pass electrons with energies above a critical value greater that the retarding voltage difference between detector system and chip test bias, reach the detection means (13, 14) and are measured.
Claim 6
Dependent Claim
39 words
A system for dynamic testing of integrated circuit process intermediates according to claim 1 characterized in that the energy of said laser means (7) is controlled close to the emission threshold for primary or secondary electrons for improved sensitivity.
Claim 7
Dependent Claim
33 words
A system for dynamic testing of integrated circuit process intermediates according to claim 1 characterized in that said detector bias means comprises a grid (11) of stainless steel mesh having high light transmittivity.
Claim 8
Dependent Claim
38 words
A system for dynamic testing of integrated circuit process intermediates according to claim 1 characterized in that the energy of said laser modification means (8) is controlled close to the emission threshold for secondary electrons for improved sensitivity.
References Cited (Backward Citations)
EP0129508A1
Cited
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