IEC 60749-17 pdf download – Semiconductor devices – Mechanical and climatic test methods – Part 17: Neutron irradiation

IEC 60749-17 pdf download – Semiconductor devices – Mechanical and climatic test methods – Part 17: Neutron irradiation
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The neutron irradiation test is performed to determine the susceptibility of semiconductordevices to degradation in the neutron environment.The tests described herein are applicableto integrated circuits and discrete semiconductor devices. This test is intended for military-and space-related applications. It is a destructive test.
The objectives of the test are as follows:
a) to detect and measure the degradation of critical semiconductor device parameters as
a function of neutron fluence, and
b) to determine if specified semiconductor device parameters are within specified limits after
exposure to a specified level of neutron fluence (see Clause 4).
Test apparatus
2.1Test instruments
Test instrumentation to be used in the radiation test shall be standard laboratory electronictest instruments such as power supplies, digital voltmeters, and pico-ammeters, etc., capableof measuring the electrical parameters required.
2.2Radiation source
The radiation source used in the test shall be in a pulsed reactor.
2.3Dosimetry equipment
a) Fast-neutron threshold activation foils such as 32S, 54Fe, and 58Ni.b) CaF2 thermoluminescence dosimeters (TLDs).
c) Appropriate activation foil counting and TLD readout equipment.
2.4Dosimetry measurements
2.4.1Neutron fluences
The neutron fluence used for device irradiation shall be obtained by measuring the amount ofradioactivity induced in a fast-neutron threshold activation foil such as 32S, 54Fe, or 58Ni,
irradiated simultaneously with the device.
Astandard method for converting the measured radioactivity in the specific activation foilemployed into a neutron fluence shall be used.The conversion of the foil radioactivity into aneutron fluence requires a knowledge of the neutron spectrum incident on the foil. If thespectrum is not known, it shall be determined by use of a recognised national standard orequivalent.
Once the neutron energy spectrum has been determined and the equivalent monoenergetic fluence calculated, then an appropriate monitor foil (such as 32 S, 54 Fe, or 58 Ni) should be used in subsequent irradiations to determine the neutron fluence. Thus, the neutron fluence is described in terms of the equivalent monoenergetic neutron fluence per unit monitor response. Use of a monitor foil to predict the equivalent monoenergetic neutron fluence is valid only if the energy spectrum remains constant.
2.4.2 Dose measurements If absorbed dose measurements of the gamma-ray component during the device test irradiations are required, then such measurements shall be made with CaF2 thermo- luminescence dosimeters (TLDs), or their equivalent. These TLDs shall be used in accordance with the recommendations of recognised national standards or their equivalent.
3 3.1 Procedure Safety requirements Neutron irradiated devices may be radioactive. Handling and storage of test specimens or equipment subjected to radiation environments shall be governed by the procedures established by the local Radiation Safety Officer or Health Physicist.
3.2 Test samples A test sample shall be randomly selected and consist of a minimum of 1 0 devices, unless otherwise specified. All sample devices shall have met all the requirements of the relevant specification for that device. Each device shall be serialised to enable preand post-test identification and comparison.
3.3 3.3.1 Pre-exposure Electrical tests Pre-exposure electrical tests shall be performed on each device as required. Where delta parameter limits are specified, the pre-exposure data shall be recorded.
3.3.2 Exposure set-up Each device shall be mounted unbiased and have its terminal leads either all shorted or all open. For MOS devices or any microcircuit containing an MOS element, all leads shall be shorted. An appropriate mounting fixture which will accommodate both the sample and the required dosimeters (at least one actuation foil and one CaF2 TLD) shall be used. The configuration of the mounting fixture will depend on the type of reactor facility used and should be discussed with the reactor facility personnel. Test devices shall be mounted in such a way that the total variation of fluence over the entire sample does not exceed 20 percent. Reactor facility personnel shall determine both the position of the fixture and the appropriate pulse level required to achieve the specified neutron fluence level.