MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第117页

MIL-STD-883F METHOD 1019.6 7 March 2003 1 METHOD 1019.6 IONIZING RADI ATION (TOTAL DOSE) TEST PROCEDURE 1. PURPOSE . This test procedur e defines the requi rements for t esti ng packaged s emiconduc tor i ntegrat ed cir …

MIL-STD-883F

METHOD 1018.4

18 June 2004

This page intentionally left blank

MIL-STD-883F

METHOD 1019.6

7 March 2003

METHOD 1019.6

IONIZING RADIATION (TOTAL DOSE) TEST PROCEDURE

1. PURPOSE

. This test procedure defines the requirements for testing packaged semiconductor integrated circuits for

ionizing radiation (total dose) effects from a cobalt-60 (

Co) gamma ray source. The testing includes both standard room

temperature irradiation as well as irradiation at elevated temperature. In addition this procedure provides an accelerated

annealing test for estimating low dose rate ionizing radiation effects on devices. This annealing test is important for low

dose-rate or certain other applications in which devices may exhibit significant time-dependent effects. This procedure

addresses only steady state irradiations, and is not applicable to pulse type irradiations. This test may produce severe

degradation of the electrical properties of irradiated devices and thus should be considered a destructive test.

1.1 Definitions

. Definitions of terms used in this procedure are given below:

a. Ionizing radiation effects

. The changes in the electrical parameters of a device or integrated circuit resulting from

radiation-induced charge. These are also referred to as total dose effects.

b. In-flux test

. Electrical measurements made on devices during irradiation exposure.

c. Not in-flux test

. Electrical measurements made on devices at any time other than during irradiation.

d. Remote tests

. Electrical measurements made on devices which are physically removed from the radiation

location.

e. Time dependent effects

. Significant degradation in electrical parameters caused by the growth or annealing or

both of radiation-induced trapped charge after irradiation. Similar effects also take place during irradiation.

f. Accelerated annealing test. A procedure utilizing elevated temperature to accelerate time-dependent effects.

g. Enhanced Low Dose Rate Sensitivity (ELDRS). Used to refer to a part that shows enhanced radiation induced

damage at dose rates below 50 rad(Si)/s.

h. Overtest. A factor that is applied to the specification dose to determine the test dose level that the samples must

pass to be acceptable at the specification level. An ovetest factor of 1.5 means that the parts must be tested at 1.5

times the specification dose.

i. Parameter Delta Design Margin (PDDM). A design margin that is applied to te radiation induced change in an

electrical parameter. For a PDDM of 2 the change in a parameter at a specified dose from the pre-irradiation value

is multiplied by two and added to the post-irradiation value to see if the sample exceeds the post-irradiation

parameter limit. For example, if the pre-irradiation value of Ib is 30 nA and the post-irradiation value at 20 krad(Si)

is 70 nA (change in Ib is 40 nA), then for a PDDM of 2 the post-irradiation value would be 110 nA (30 nA + 2 X 40

nA). If the allowable post-irradiation limit is 100 nA the part would fail.

2. APPARATUS

. The apparatus shall consist of the radiation source, electrical test instrumentation, test circuit board(s),

cabling, interconnect board or switching system, an appropriate dosimetry measurement system, and an environmental

chamber (if required for time-dependent effects measurements or elevated temperature irradiation). Adequate precautions

shall be observed to obtain an electrical measurement system with sufficient insulation, ample shielding, satisfactory

grounding, and suitable low noise characteristics.

2.1 Radiation source

. The radiation source used in the test shall be the uniform field of a

Co gamma ray source.

Uniformity of the radiation field in the volume where devices are irradiated shall be within ±10 percent as measured by the

dosimetry system, unless otherwise specified. The intensity of the gamma ray field of the

Co source shall be known with

an uncertainty of no more than ±5 percent. Field uniformity and intensity can be affected by changes in the location of the

device with respect to the radiation source and the presence of radiation absorption and scattering materials.

MIL-STD-883F

METHOD 1019.6

7 March 2003

2.2 Dosimetry system

. An appropriate dosimetry system shall be provided which is capable of carrying out the

measurements called for in 3.2. The following American Society for Testing and Materials (ASTM) standards and guidelines

or other appropriate standards and guidelines shall be used:

ASTM E 666 - Standard Method for Calculation of Absorbed Dose from Gamma or X Radiation.

ASTM E 668 - Standard Practice for the Application of Thermoluminescence Dosimetry (TLD) Systems

for Determining Absorbed Dose in Radiation-Hardness Testing of Electronic Devices.

ASTM E 1249 - Minimizing Dosimetry Errors in Radiation Hardness Testing of Silicon Electronic Devices.

ASTM E 1250 - Standard Method for Application of Ionization Chambers to Assess the Low Energy Gamma

Component of Cobalt 60 Irradiators Used in Radiation Hardness Testing of Silicon Electronic

Devices.

ASTM E 1275 - Standard Practice for Use of a Radiochromic Film Dosimetry System.

ASTM F 1892 - Standard Guide for Ionizing Radiation (Total Dose) Effects Testing of Semiconductor Devices.

These industry standards address the conversion of absorbed dose from one material to another, and the proper use of

various dosimetry systems. 1

2.3 Electrical test instruments

. All instrumentation used for electrical measurements shall have the stability, accuracy,

and resolution required for accurate measurement of the electrical parameters. Any instrumentation required to operate in a

radiation environment shall be appropriately shielded.

2.4 Test circuit board(s)

. Devices to be irradiated shall either be mounted on or connected to circuit boards together with any

associated circuitry necessary for device biasing during irradiation or for in-situ measurements. Unless otherwise specified, all

device input terminals and any others which may affect the radiation response shall be electrically connected during irradiation,

i.e., not left floating. The geometry and materials of the completed board shall allow uniform irradiation of the devices under test.

Good design and construction practices shall be used to prevent oscillations, minimize leakage currents, prevent electrical

damage, and obtain accurate measurements. Only sockets which are radiation resistant and do not exhibit significant leakages

(relative to the devices under test) shall be used to mount devices and associated circuitry to the test board(s). All apparatus

used repeatedly in radiation fields shall be checked periodically for physical or electrical degradation. Components which are

placed on the test circuit board, other than devices under test, shall be insensitive to the accumulated radiation or they shall be

shielded from the radiation. Test fixtures shall be made such that materials will not perturb the uniformity of the radiation field

intensity at the devices under test. Leakage current shall be measured out of the radiation field. With no devices installed in the

sockets, the test circuit board shall be connected to the test system such that all expected sources of noise and interference are

operative. With the maximum specified bias for the test device applied, the leakage current between any two terminals shall not

exceed ten percent of the lowest current limit value in the pre-irradiation device specification. Test circuit boards used to bias

devices during accelerated annealing must be capable of withstanding the temperature requirements of the accelerated

annealing test and shall be checked before and after testing for physical and electrical degradation.

2.5 Cabling

. Cables connecting the test circuit boards in the radiation field to the test instrumentation shall be as short as

possible. If long cables are necessary, line drivers may be required. The cables shall have low capacitance and low

leakage to ground, and low leakage between wires.

2.6 Interconnect or switching system

. This system shall be located external to the radiation environment location, and

provides the interface between the test instrumentation and the devices under test. It is part of the entire test system and

subject to the limitation specified in 2.4 for leakage between terminals.

2.7 The environmental chamber

. The environmental chamber for time-dependent effects testing, if required, shall be

capable of maintaining the selected accelerated annealing temperature within ±5°C.

/ Copies may be obtained from the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.