JPH01248070A - Semiconductor device testing equipment - Google Patents

Abstract

PURPOSE:To effect simultaneously acceleration life estimation examination and measurement of dependence of alpha-particle energy by a method wherein a radiation source and a semiconductor device to be examined are located in the air with thickness of the air layer between the two optionally set, and energy of entering radioactive rays is converted into thickness of the air layer when malfunction occurs in the semiconductor device. CONSTITUTION:A control device of alpha-ray source movement is used to move an alpha-ray source 3 to the position of a photoelectric switch 4 which is the reference position, and movement amount that is thickness (l) of the air layer and duration time are controlled according to preset movement amount of the alpha-ray source 3. A pulse motor is used for movement so that movement of the alpha-ray source 3 is intermittent and continuous to irradiate alpha-rays having a continuous energy distribution to a semiconductor device 1. When a malfunction check unit 6 detects malfunction during irradiation, a malfunction signal from this unit is transmitted to an air layer thickness detection unit 7, where a signal of the number of pulses is received and thickness (l) is calculated. By adding it to a tester unit 8, attenuation amount of the energy from thickness (l) is calculated and converted into an energy value to show a malfunction state.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a testing device for semiconductor devices, and relates to a test device for semiconductor devices.

The present invention relates to an apparatus for testing the occurrence of soft errors when a semiconductor device is irradiated with radiation.

[Conventional technology]

One of the malfunctions of semiconductor devices is a phenomenon called soft error. The radiation that causes this is alpha rays, whose sources are the Si chips, Al wiring, etc. that make up the semiconductor device.
U (uranium) is contained in trace amounts in glass protective film materials and plastics, ceramics, and other materials for back-caging these materials.

It is a natural radioactive substance such as Th (thorium). and,
U, Th, etc. emit α particles (He atomic nuclei) by natural decay, and when these α particles are pressed into a semiconductor device, electron-hole pairs are generated over a range KG. M.O.S.
In a dynamic memory, if these generated electrons accumulate in an empty potential well portion of a memory cell beyond a certain level, a soft error occurs. Furthermore, in high-speed bipolar static memory, the generated electrons flow as a noise current and cause soft errors. Such soft error problems tend to increase as semiconductor devices become more highly integrated and operate faster.

Therefore, it is necessary to evaluate soft errors of semiconductor devices using alpha rays. When making this assessment, alpha particles naturally emitted from packaging materials alone are not sufficient.

The test takes a long time because the radiation density of alpha particles is extremely low. Therefore, in general, accelerated evaluation tests using natural radioactive materials or artificial radioactive materials are conducted to determine the radiation density of alpha particles.

To evaluate the characteristics of soft errors, the semiconductor device under test is irradiated with α particles emitted from an α-ray source, and the time until a soft error occurs and the number of errors occurring within a certain irradiation time are measured, and the α-ray tolerance is measured. Evaluate. The testing methods include performance checks on mass-produced products (100% inspection,
(sampling inspections, etc.) and market failure rate predictions, etc.
Accelerated life evaluation tests that measure alpha-ray resistance by irradiating semiconductor devices with radiation similar to the alpha-ray energy distribution emitted from package materials, etc., and 2) improvement and development effects of semiconductor devices, level comparisons between products, When detecting singular bits (defective bits) or evaluating problems in the manufacturing process, α
The radiation tolerance is the irradiated α particle energy.

Since it depends on the angle of incidence, there are tests to evaluate the characteristics of these parameters in detail.

The present applicant previously applied for 1%. -121024, the α-ray energy attenuation amount is controlled by changing the distance between the α-ray source in the air and the semiconductor device under test (the distance that α particles fly in the air: air layer thickness), Each irradiation α is performed by changing the α-ray energy irradiated to the semiconductor device.
Measure the alpha ray resistance of semiconductor devices for each particle energy,
Furthermore, there is a test method that performs an accelerated life evaluation test by irradiating the semiconductor device with alpha rays while changing the air layer thickness intermittently or continuously, and irradiating the semiconductor device with alpha rays that have a continuous and wide energy distribution. is proposed.

[Problem to be solved by the invention]

Although the conventional technology proposed above can perform accelerated life tests and energy-dependent characteristic evaluations more accurately than before, it still has the problem that the tests take a long time due to the first reason.

When evaluating the α-particle energy dependence characteristics of a semiconductor device under test, the thickness of the air layer through which the α-particles fly is controlled in order to change the α-particle energy applied to the semiconductor device under test. However, the α-particle energy-dependent characteristics exhibit a parabolic characteristic curve curving downward, as shown in Figure 2.
Moreover, even if the semiconductor device is of the same type, the characteristic curve 9
, 10, 11, the α of each semiconductor device is
Line tolerance (MTBF: Mean Time Be
tween Failure ) are significantly different. That is, the α particle energy value E at which the MTBF has a minimum value differs from semiconductor device to semiconductor device. This energy value Eo is the energy value that reduces the alpha ray tolerance of the semiconductor device under test. Therefore, in order to obtain the above energy value EO, press the button.
It is necessary to cover a wide measurement energy range for irradiating semiconductor devices, resulting in a large number of measurement energy points (number of tests), and it takes a long time to measure alpha ray tolerance.

An object of the present invention is to solve the problems of the prior art described above.
An object of the present invention is to provide a semiconductor device testing device for evaluating the alpha ray resistance of a semiconductor device in a short time.

[Means to solve the problem]

The above purpose is to place a radiation source in the air and a semiconductor device under test 1f'.
& arrangement, and arbitrarily set the thickness of the air layer between the two to attenuate the radiation energy in the air and make it incident on the semiconductor device under test to test the malfunction of the semiconductor device. means for detecting the thickness of an air layer through which radiation passes when a malfunction occurs in the semiconductor device;

This can be achieved by providing a means for converting the incident radiation energy at that time by the air layer thickness.

[Effect]

By utilizing the energy attenuation characteristic of air as an α-ray energy attenuation means and changing the air layer thickness intermittently or continuously, α-rays having a continuous and wide energy distribution can be generated. Here, there is a predetermined relationship between the energy of an α particle and its range in the air. Therefore, by controlling the thickness of the air layer through which α particles are emitted, generating α rays with a continuous energy distribution and irradiating the semiconductor device under test with this, the thickness of the air layer through which the α particles pass when a malfunction occurs is detected. From the thickness of the air layer, it is possible to determine the energy of α particles when they enter the semiconductor device under test. Then, from the obtained relationship between the α particle energy value at the time of malfunction occurrence and the frequency of malfunction occurrence, the α particle energy value Eo (energy dependent characteristic) that the α ray tolerance shows at the minimum value can be determined.

As described above, by determining the α particle energy at the time of malfunction during the accelerated life evaluation test, the α particle energy dependent characteristics can also be measured at the same time.

Measurement time can be shortened.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a configuration diagram of a semiconductor device testing apparatus according to an embodiment of the present invention. In FIG. 1, 1 is a semiconductor device under test, 2 is a socket for extracting signals from the semiconductor device under test 1, 3 is an α-ray source that emits α-particles, and 4 is an α-ray source 3.
5 is an α-ray source movement control device for moving the α-ray source 3 up and down and holding it for the required time;
6 is a malfunction check device that compares information read from the semiconductor device under test 1 with normal data to check whether a malfunction has occurred; 7 receives a signal from the malfunction check device 6 when a malfunction occurs, and receives a signal from the α-ray source movement control device 5; α source 3
means for detecting the current position (l: air layer thickness), and 8 includes an incident radiation energy conversion means for converting the air layer thickness at the time of malfunction into an α particle energy value. 9 is a dark box for shielding the semiconductor device under test 1 from light entering from the outside.

Figure 3 shows α particle energy and range in air (α
This is a characteristic graph showing the relationship between the distance a particle flies in the air before losing energy. As can be seen from this graph, by controlling the distance that the α particles fly in the air (air layer thickness), the energy of the α rays irradiated to the semiconductor device under test can be changed.

Next, the operation of the test apparatus configured as described above will be explained.

First, the α-ray source movement control device 5 moves the α-ray source 3 to the photoelectric switch 4 position (reference position).

Then, the α-ray source movement control device 5 controls the moving distance (l: air layer thickness) and holding time according to a predetermined movement amount of the α-ray source 3. In this embodiment, a pulse motor is used to drive the α-ray source 3 up and down. With a pulse motor,
Since the moving distance of the α-ray source 3 per pulse is a low value, the moving distance is proportional to the number of pulses. According to the above method, α-rays having a continuous energy distribution can be generated by moving the α-ray source 3 intermittently and continuously, and the semiconductor device under test t1 is irradiated with the α-rays. When the malfunction check device 6 detects a malfunction in the semiconductor device under test 1 during irradiation, a malfunction occurrence signal is sent to the air layer thickness detection means 7. Upon receiving this signal, the air layer thickness detecting means 7 receives a pulse number signal from the α-ray source movement control device 5 indicating how many pulses 'Y' are applied to the pulse motor relative to the reference position, and determines the air layer thickness from this value. l is calculated and sent to the tester means 8. In tester means 8.

The air layer thickness l is determined from the number of pulses, the attenuation amount of α particle energy is calculated from this air layer thickness, and the result is converted to the α particle energy value incident on the semiconductor device under test 1 to perform a malfunction test.

As described above, according to this embodiment, by determining the energy value of the incident α particle when a malfunction occurs in the accelerated life evaluation test, the α particle energy dependence characteristics can also be measured at the same time, and the α ray tolerance can be measured. It can save time.

In this embodiment, the photoelectric switch 4 was used to detect the reference position of the α-ray source 30, but it is also possible to detect it mechanically (for example, with a limit switch), and it goes without saying that the method is not limited to the above method. .

〔Effect of the invention〕

According to the present invention, it is possible to simultaneously measure the accelerated life evaluation test for malfunction and the α-particle energy dependence characteristics using a simpler method than before, and the time required to evaluate the characteristics of a semiconductor device under test can be significantly shortened compared to the conventional method. be able to.

[Brief explanation of the drawing]

Fig. 1 shows the configuration of a test device according to an embodiment of the invention, Fig. 2 shows a graph of α particle energy dependence characteristics of a semiconductor device under test, and Fig. 3 shows the relationship between α particle energy and range in air. It is a characteristic graph showing. 1... Semiconductor device under test, 3... α-ray source. 4...Photoelectric switch, 5...α-ray source movement control device. 7...Air layer thickness detection means. 8... Tester means (includes incident radiation energy conversion means) Fig. 1 Fig. 2 Fig. da + 1 ne > LA” - (fiaV) Rod 3 Fig.

Claims (1)

[Claims] 1. Place the radiation source and the semiconductor device under test in the air, and set the air layer thickness (distance) between them arbitrarily to attenuate the radiation energy before it enters the semiconductor device under test. In a semiconductor device testing apparatus for testing malfunction of the semiconductor device, there is provided means for detecting the thickness of an air layer through which radiation passes when a malfunction of the semiconductor device occurs, and means for detecting the incident radiation energy at that time by the air layer thickness. 1. A testing device for a semiconductor device, comprising: means for converting.