JPH073454B2 - Semiconductor device testing equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a testing device for a semiconductor device testing device, and more particularly to a device for generating a soft error when a semiconductor device is irradiated with radiation.

[Conventional technology]

One of the malfunctions of a semiconductor device is a phenomenon called a soft error. The radiation that causes this is α rays, and its source is a minute amount in Si chips, Al wiring, glass protective film materials and the plastics, ceramics and other materials for packaging these which constitute the semiconductor device. Natural radioactive substances such as U (uranium) and Th (thorium) are included. Then, U, Th, and the like emit α particles (nuclei of He) by spontaneous decay, and when these α particles enter the semiconductor device, electron-hole pairs are generated along this range. MO
In the S dynamic memory, a soft error occurs when these generated electrons accumulate in the empty potential well portion of the memory cell for a certain amount or more. Further, in the high speed bipolar static memory, the generated electrons flow as a noise current to cause a soft error. The problem of such soft error tends to increase as the integration and speed of semiconductor devices increase.

Therefore, it is necessary to evaluate the soft error of the semiconductor device by α rays. When this evaluation is performed, it takes a long time for the test because only the α particles naturally emitted from the packaging material have a very small radiation density. Therefore, generally, an accelerated evaluation test is performed using a natural radioactive material or an artificial radioactive material having a large α particle radiation density.

The soft error characteristics are evaluated by irradiating the semiconductor device under test with α particles emitted from the α-ray source, measuring the time until a soft error occurs and the number of error occurrences within a fixed irradiation time, and measuring the α-ray tolerance. Evaluate. The test methods are as follows: 1) When performing performance checks (100% inspection, sampling inspection, etc.) and prediction of market failure rate in mass-produced products, the radiation similar to the α-ray energy distribution radiated from the packaging material is used. Accelerated life evaluation test for irradiating semiconductor device to measure α-ray tolerance, 2) Improvement and development effect of semiconductor device, level comparison between products, unique bit (defective bit)
When detecting the
Since the α-ray resistance depends on the irradiation α-particle energy and the incident angle, there is a test for detailed characterization of these parameters.

The applicant previously changed the distance between the α-ray source in air and the semiconductor device under test (distance in which α particles fly in air: air layer thickness) in Japanese Patent Application No. 61-121024. By controlling the α-ray energy deceleration amount by changing the α-ray energy irradiated to the semiconductor device to measure the α-ray resistance of the semiconductor device for each irradiation α-particle energy, further, intermittently the air layer thickness or It proposes a test method for performing accelerated life evaluation test by irradiating the semiconductor device with α-rays while continuously changing it and irradiating the semiconductor device with α-rays having a continuous and wide energy distribution.

[Problems to be Solved by the Invention]

The conventional technique according to the above proposal can perform an accelerated life test and an energy-dependent characteristic evaluation more accurately than before, but has a problem that the test takes time due to the following reasons.

When evaluating the α-particle energy dependence characteristic of the semiconductor device under test, the air layer thickness over which the α-particles fly is controlled in order to change the α-particle energy with which the semiconductor device under test is irradiated. However, the α-particle energy-dependent characteristic shows a parabolic characteristic curve that curves downward as shown in FIG.
Moreover, even if the same type of semiconductor device is used, the characteristic curve
As shown by 0 and 11, the α-ray tolerance (MT
BF: Mean Time Between Failure) is very different.
That is, the α-particle energy value E _{0 at} which the MTBF exhibits a minimum value differs for each semiconductor device. This energy value E ₀ is an energy value that reduces the α-ray resistance of the semiconductor device under test.
Therefore, in order to obtain the energy value E ₀ , it is necessary to set a wide range of measurement energy to be applied to the semiconductor device. As a result, the number of measurement energy points (the number of tests) increases, and it takes a long time to measure the α-ray tolerance. Is needed.

The object of the present invention is to eliminate the above-mentioned problems of the prior art,
It is an object of the present invention to provide a semiconductor device testing apparatus for evaluating the α-ray resistance of a semiconductor device in a short time.

[Means for Solving the Problems]

The above-mentioned object is to arrange a radiation source and a semiconductor device under test in the air, to arbitrarily variably set an air layer thickness between the two, to attenuate the radiation energy in the air, and to make it enter the semiconductor device under test. In a semiconductor device testing apparatus for testing malfunction of a semiconductor device, means for detecting an air layer thickness through which radiation passes when a malfunction of the semiconductor device occurs, and incident radiation energy at that time are converted into an air layer thickness. It is achieved by providing means.

[Action]

By utilizing the energy attenuation characteristic of air as the α-ray energy attenuating 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 α particles and their range in air. Therefore, by controlling the thickness of the air layer that blows the α particles to generate α rays with a continuous energy distribution, irradiating this to the semiconductor device under test, and detecting the thickness of the air layer through which the α particles pass when a malfunction occurs. From the thickness of the air layer, the α-particle energy when entering the semiconductor device under test can be determined. Then, the α-particle energy value E ₀ (energy dependence characteristic) at which the α-ray resistance has a minimum value can be obtained from the obtained relationship between the α-particle energy value at the time of malfunction occurrence and the malfunction occurrence frequency.

As described above, by obtaining the α-particle energy when a malfunction occurs during the accelerated life evaluation test, the α-particle energy dependence characteristic can be measured at the same time, and the 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 block 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 taking out a signal 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.
Is a photoelectric switch for detecting the position of the α-ray source, and 5 is an α-ray source movement control device for moving the α-ray source 3 up and down and holding it for a required time, 6
Is a malfunction check device for comparing the information read from the semiconductor device under test 1 with normal data to check whether or not there is a malfunction, and 7 receives a signal from the malfunction check device 6 when a malfunction occurs, and outputs from the α ray source movement control device 5 α Means for detecting the current position of the radiation source 3 (l: air layer thickness), 8 is provided with incident radiation energy conversion means for converting the air layer thickness at the time of malfunction to α particle energy value, malfunction frequency and α particle energy value Also, a tester means for recording the time from the irradiation of α rays to the occurrence of a malfunction and the like, and 9 is a dark box for shielding the semiconductor device 1 under test from the light entering from the outside.

Figure 3 shows α particle energy and range in air (α
It is a characteristic graph which shows the relationship of the distance which the particle flew in the air before it lost energy. As can be seen from this graph, by controlling the distance (air layer thickness) that the α particles fly in the air, the α particle energy with which the semiconductor device under test is irradiated can be changed.

Next, the operation of the test apparatus having the above-mentioned configuration will be described.

First, the α-ray source movement control device 5 moves the α-ray source 3 to the position of the photoelectric switch 4 (reference position). Then, the α-ray source movement control device 5 controls the moving distance (l: air layer thickness) and the holding time according to the predetermined moving 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. When a pulse motor is used, the moving distance is proportional to the number of pulses because the moving distance of the α-ray source 3 per pulse is already set. By the above method, the α-ray source 3 is intermittently and continuously moved to obtain α having a continuous energy distribution.
Can be generated, and the semiconductor device under test 1 is irradiated with this. If the malfunction check device 6 detects a malfunction of the semiconductor device under test 1 during irradiation, a malfunction occurrence signal is sent to the air layer thickness detecting means 7. Upon receiving this signal, the air layer thickness detecting means 7 receives from the α-ray source movement control device 5 how many pulses the pulse motor has been applied to the reference position and the pulse number signal, and from this value the air layer thickness is detected. 1 is calculated and sent to the tester means 8. The tester means 8 obtains the air layer thickness 1 from the pulse number, calculates the attenuation amount of the α particle energy from this air layer thickness, converts it into the α particle energy value incident on the semiconductor device under test 1, and tests the malfunction. I do.

As described above, according to the present embodiment, the α-particle energy dependence characteristic can be measured at the same time by determining the α-particle energy value that is incident when the accelerated life evaluation test malfunction occurs, and the α-ray resistance measurement time Can be shortened.

In this embodiment, the photoelectric switch 4 is used to detect the reference position of the α-ray source 3, but it is also possible to detect mechanically (for example, a limit switch) other than this, and needless to say, the method is not limited to the above. Yes.

〔The invention's effect〕

According to the present invention, the accelerated life evaluation test for malfunction and the α-particle energy dependence characteristic can be simultaneously measured by a simpler method than before, and the characteristic evaluation time of the semiconductor device under test is significantly shortened as compared with the conventional method. be able to.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a test apparatus according to an embodiment of the present invention, FIG. 2 is a graph of α-particle energy dependence characteristics of a semiconductor device under test, and FIG. 3 is a relationship between α-particle energy in air and range. It is a characteristic graph shown. 1 ... Semiconductor device under test, 3 ... α-ray source, 4 ... Photoelectric switch, 5 ... α-ray source movement control device, 7 ... Air layer thickness detecting means, 8 ... Tester means (incident radiation energy conversion) Means are included.)

Claims (1)

[Claims] 1. A semiconductor device to be tested by arranging a radiation source and a semiconductor device to be tested in air, and variably setting an air layer thickness (distance) between them to attenuate radiation energy in the air. In a semiconductor device test apparatus for injecting a semiconductor device into a malfunction test of the semiconductor device, a means for detecting a thickness of an air layer through which radiation passes when the malfunction of the semiconductor device occurs, and an incident radiation energy at that time A device for testing a semiconductor device, which is provided with means for converting the thickness.