MIL- STD-883F 2004 TEST METHOD STANDARD MICROCIRCUITS - 第139页

MIL-STD-883F METHOD 1021.2 15 November 1991 1 METHOD 1021.2 DOSE RATE UPSET TESTING OF DIGITAL MI CROCIRCUITS 1. PURPOSE . This test procedur e defines the requi rements for t esti ng the res ponse of pac kaged di gital …

MIL-STD-883F

METHOD 1020.1

15 November 1991

FIGURE 1020-2. Linear device latchup screen test photograph (50 µs/div)

MIL-STD-883F

METHOD 1021.2

15 November 1991

METHOD 1021.2

DOSE RATE UPSET TESTING OF DIGITAL MICROCIRCUITS

1. PURPOSE

. This test procedure defines the requirements for testing the response of packaged digital integrated

circuits to pulsed ionizing radiation. A flash x-ray or linear accelerator is used as a source of pulses of ionizing radiation.

The response may include transient output signals, changes in the state of internal storage elements, and transient current

surges at inputs, outputs, and power supply connections. The dose rate at which logic or change-of-state errors first occur

is of particular interest in many applications.

1.1 Definitions

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

a. Dose rate threshold for upset. The dose rate which causes either:

(1) A transient output upset for which the change in output voltage of an operating digital integrated circuit goes

either above or below (as appropriate) specified logic levels (see 3.2 on transient voltage criteria), and the

circuit spontaneously recovers to its preirradiation condition after the radiation pulse subsides, or

(2) A stored data or logic state upset for which there is a change in the state of one or more internal memory or

logic elements that does not

recover spontaneously after the radiation pulse. However, the circuit can be

restored to its preirradiation condition by applying the same sequence of logic signals to its inputs that were

previously used to establish the preirradiation condition, or

(3) A dynamic upset which results in a change in the expected output or stored test pattern of a device that is

functionally operating during the time it is irradiated. The upset response may depend on the precise time

relationship between the radiation pulse and the operating cycle of the device. For operations requiring

many clock signals, it may be necessary to use a wide radiation pulse.

b. Dose rate. Energy absorbed per unit time per unit mass by a given material from the radiation field to which it is

exposed.

c. Combinational logic circuit. A digital logic circuit with the property that its output state is solely determined by the

logic signals at its inputs. Combinational logic circuits contain no internal storage elements. Examples of

combinational circuits include gates, multiplexers, and decoders.

d. Sequential logic circuit. A digital logic circuit with the property that its output state at a given time depends on the

sequence and time relationship of logic signals that were previously applied to its inputs. Sequential logic circuits

contain internal storage elements. Examples of sequential logic circuits include memories, shift registers,

counters, and flip-flops.

e. State vector. A state vector completely specifies the logic condition of all elements within a logic circuit. For

combinational circuits the state vector includes the logic signals that are applied to all inputs; for sequential

circuits the state vector must also include the sequence and time relationship of all input signals (this may include

many clock cycles).

MIL-STD-883F

METHOD 1021.2

15 November 1991

1.2 Interferences

. There are several interferences that need to be considered when this test procedure is applied. These

include:

a. Total dose damage. Devices may be permanently damaged by total dose. This limits the number of radiation

pulses that can be applied during transient upset testing. The total dose sensitivity depends on fabrication

techniques and device technology. MOS devices are especially sensitive to total dose damage. Newer bipolar

devices with oxide-isolated sidewalls may also be affected by low levels of total dose. The maximum total dose to

which devices are exposed must not exceed 20 percent of the typical total dose failure level of the specific part

type.

b. Steps between successive radiation levels. The size of the steps between successive radiation levels limits the

accuracy with which the dose rate upset threshold is determined. Cost considerations and total dose damage

limit the number of radiation levels that can be used to test a particular device.

c. Latchup. Some types of integrated circuits may be driven into a latchup condition by transient radiation. If latchup

occurs, the device will not function properly until power is temporarily removed and reapplied. Permanent damage

may also occur, primarily due to the large amount of localized heating that results. Although latchup is an

important transient response mechanism, this procedure does not apply to devices in which latchup occurs.

Functional testing after irradiation is required to detect internal changes of state, and this will also detect latchup.

However, if latchup occurs it will usually not be possible to restore normal operation without first interrupting the

power supply.

d. Limited number of state vectors. Cost, testing time, and total dose damage usually make it necessary to restrict

upset testing to a small number of state vectors. These state vectors must include the most sensitive conditions

in order to avoid misleading results. An analysis is required to select the state vectors used for radiation testing to

make sure that circuit and geometrical factors that affect the upset response are taken into account (see 3.1).

2. APPARATUS

. Before testing can be done, the state vectors must be selected for radiation testing. This requires a

logic diagram of the test device. The apparatus used for testing shall consist of the radiation source, dosimetry equipment,

a test circuit board, line drivers, cables, and electrical test instrumentation to measure the transient response, provide bias,

and perform functional tests. Adequate precautions shall be observed to obtain an electrical measurement system with

ample shielding, satisfactory grounding, and low noise from electrical interference or from the radiation environment.

2.1 Radiation source

. The radiation source used in this test shall be either a flash x-ray machine (FXR) used in the

photon mode or a linear accelerator (LINAC) used in the electron beam mode. The LINAC beam energy shall be greater

than 10 MeV. The radiation source shall provide a uniform (within 20 percent) radiation level across the area where the

device and the dosimeter will be placed. The radiation pulse width for narrow pulse measurements shall be between 10 and

50 ns. For narrow pulse measurements either a LINAC or FXR may be used. Wide pulse measurements (typically 1 - 10

µs) shall be performed with a LINAC. The pulse width for LINAC irradiations shall be specified. The dose rate at the

location of the device under test shall be adjustable between 10

and 10

rads(Si)/s (or as required) for narrow pulse

measurements and between 10

and 10

rads(Si)/s (or as required) for wide pulse measurements. Unless otherwise

specified, a test device exposed to a total dose that exceeds 20 percent of the total dose failure level shall be considered as

destructively tested and shall be removed from the lot (see 1.2a).

2.2 Dosimetry equipment

. Dosimetry equipment must include a system for measuring total dose, such as a

thermoluminescent dosimeter (TLD) or calorimeter, a pulse shape monitor, and an active dosimeter that allows the dose rate

to be determined from electronic measurements, e.g., a p-i-n detector, Faraday cup, secondary emission monitor, or current

transformer.