JPH073453B2 - Semiconductor device testing equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device test apparatus, and more particularly to a semiconductor device test apparatus suitable for shortening a period between characteristic evaluations of a semiconductor device under test.

[Conventional technology]

Generally, one of the malfunctions of semiconductor devices is a phenomenon called a soft error. Radiation that causes this is α rays, and its source is contained in trace amounts in Si chips, Al wiring, glass protective film materials that compose semiconductor devices and plastics, ceramics and other materials for packaging these. It is a natural radioactive substance such as U (uranium) and Th (thorium). Then, the U, Th, etc. emit α particles (nuclei of He) by natural decay, and when these α particles enter the semiconductor device, electron-hole pairs are generated along the range.

In a MOS dynamic memory, a soft error occurs when these generated electrons accumulate in an empty potential well portion of a memory cell for a certain amount or more. Further, in the high speed bipolar static memory, the generated electrons flow as a noise current, causing a soft error. The problem of such soft error tends to increase as the integration and speed of semiconductor electrons increase.

Therefore, it is necessary to evaluate the soft error of the semiconductor device by α ray. When this evaluation is performed, the α particles that are naturally emitted from the packaging material alone have a very low density of α particles, and thus the test requires a long time. Therefore, generally, an accelerated test is performed using a natural radioactive material or an artificial radioactive material having a high α particle density.

To evaluate the characteristics of soft error, α emitted from α source
The semiconductor device under test was irradiated with particles, and the time until a soft error occurred, the number of errors during a constant irradiation time, and the like were measured to evaluate the α-ray resistance. The test methods are as follows: 1) When performing performance checks (100% inspection, sampling inspection, etc.) in mass-produced products and predicting the market failure rate, radiation similar to the α-ray energy distribution shape emitted from the packaging material, etc. Life evaluation test of irradiating semiconductor device with α-ray resistance, 2) Improvement and development effect of semiconductor device, level comparison between products, detection of unique bit, evaluation of manufacturing process problems, etc. Since the α-ray resistance depends on the irradiation α-particle energy and the incident angle, it is necessary to perform a detailed characterization test on these parameters.

In contrast to the above-mentioned test method, as described in Japanese Patent Application No. 59-264459, a plurality of α-rays having different thicknesses are formed on an α-ray passing path between an α-ray source and a semiconductor device under test in a vacuum. The energy moderator piece is placed on the same plane of rotation and the disc-shaped α
Radiation similar to the α-ray energy distribution shape radiated from the packaging material or the like by forming a linear energy moderator and allowing the α rays from the α-ray source to pass through the rotated α-ray energy moderator. An energy distribution (α-ray continuous energy distribution) is generated, and the semiconductor device under test is irradiated and tested.

Further, as a method of varying the α-ray energy applied to the semiconductor device under test, the thickness of the α-ray energy moderator material piece,
The α-ray energy incident on the semiconductor device under test can be made variable by changing at least one of the materials, and the α-ray resistance is measured for each irradiation energy value.

[Problems to be solved by the invention]

 The conventional technique has the following problems.

That is, when evaluating the α-particle energy dependence characteristic of the semiconductor device under test, the thickness of the α-ray energy moderator material piece was controlled in order to change the α-particle energy applied to the semiconductor device under test. However, the α-particle energy dependence characteristic shows a concave characteristic curve as shown in FIG. 4, and even if the semiconductor devices 29, 30, 31 of the same type have the α-rays between the semiconductor devices 29, 30, 31. The tolerance (MTBF: Mean Time Betwe picture n Failure) is greatly different. That is, the α-particle energy value E _{0 at} which the MTBF shows the minimum value is different, and this α-particle energy value E ₀ is the energy value by reducing the α-ray resistance of the semiconductor device under test. Therefore, the α particle energy value
In order to obtain E ₀ , it is necessary to widen the measurement energy range with which the semiconductor device is irradiated, and 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 resistance.

An object of the present invention is to eliminate the above-mentioned problems of the conventional art and to provide a semiconductor device testing apparatus capable of simultaneously measuring the accelerated life evaluation test during malfunction and the α-particle energy dependence characteristic by a simple method.

[Means for solving problems]

The purpose is to detect a thickness of the radiation energy moderator material piece through which radiation passes when a malfunction of the semiconductor device occurs, and a thickness of the radiation energy moderator material piece input from the thickness detection means. This is achieved by providing incident radiation energy conversion means for converting the energy value of incident radiation.

[Action]

The method of generating the α-ray continuous energy distribution that irradiates the semiconductor device under test during the accelerated life evaluation test is as follows: A disk-shaped radiation energy moderator with a plurality of radiation energy moderator pieces provided on the same rotation plane. Is rotated, α rays are emitted as radiation from the radiation source into the rotated radiation energy moderator, and the radiation energy moderator is passed through the mode.

Further, since the α-particles have a large ionizing action in the substance, the α-particle energy as incident radiation energy is attenuated as the α-particles pass through the substance.

FIG. 5 is a diagram showing a transition of distribution of α particle energy when an Am (Americium) ray source is used as a radiation source and the film thickness t of the α particle energy moderator is used as a parameter. .

As can be seen from FIG. 5, as the film thickness t increases (t ₀ <t ₁ <t ₂ <t ₃ <t ₄ <t ₅ <t ₆ ), the attenuation amount of the α particle energy increases, and Thus, the relationship between each film thickness and the α-particle energy after passing through the film thickness can be obtained.

Therefore, the radiation energy moderator is rotated to generate a continuous energy distribution, which is irradiated to the semiconductor device under test, and the film thickness of the radiation energy moderator piece when the malfunctioning α particles pass is detected. As a result, the α-particle energy when entering the semiconductor device under test can be determined from the film thickness.

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 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〕

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

FIG. 1 is a vertical sectional front view showing an embodiment of the test apparatus of the present invention,
2 is a plan view of the radiation energy moderator of the test apparatus shown in FIG. 1, and FIG. 3 is a view showing a pulse train obtained from the photomicrosensor of the test apparatus shown in FIG.

The semiconductor device test apparatus of the embodiment shown in FIG. 1 includes a semiconductor device under test 1, a socket 2 for taking out a signal from the semiconductor device under test 1, and a radiation source for emitting α particles as radiation. An α-ray source 3 and an α-particle energy moderator 4 as a disk-shaped radiation energy moderator
A driving device 5 for rotating the α-particle energy moderator 4, a photomicrosensor 6, a malfunction checking device 7, and the α-particle energy moderator 4 through which the α-particles at the time of malfunction occur. A film thickness detecting means 8 as a thickness detecting means for detecting the film thickness of the α particle energy moderator part, a tester means 9 as an incident radiation energy converting means, a bell jar type vacuum chamber 10, and this vacuum chamber 10. And a vacuum pump 11 for evacuating.

As shown in FIG. 2, the α-particle energy moderator 4 has a plurality of fan-shaped α-particle energy moderator parts t ₀ , t ₁ ,
, T ₇ are arranged on the same plane of rotation to form a disk shape. Each α particle energy moderator part t ₀ , t ₁ , ..., t ₇ is
For example, they are formed of organic thin films and have different thicknesses.
Each of the α particle energy moderator parts t ₀ , t ₁ , ..., T ₇ is provided with holes for photomicrosensor detection as shown in Table 1.

The photomicrosensor 6 has a pair of a light emitting element and a light receiving element, and is adapted to detect the film thickness of the α particle energy moderator material piece. Malfunction checking device 7
Compares the information read from the semiconductor device under test 1 with normal data to check whether or not a malfunction has occurred.

When the malfunction occurs, the film thickness detection device 8 receives a signal from the malfunction check device 7, compares the signal with the signal input from the photomicrosensor 6, and the α particle energy moderator part through which the α particles pass when the malfunction occurs. The film thickness of one piece is detected.

The tester means 9 converts the α particle energy value from the film thickness of the α particle energy moderator material piece at the time of malfunction and irradiates the malfunction frequency, the α particle energy value and the α ray until the malfunction occurs. It is designed to record the time, etc.

The semiconductor device testing apparatus of the above-described embodiment is controlled and operates as follows.

First, the driving device 5 rotates the α-particle energy moderator 4.

In a state in which the α particle energy moderator 4 is rotated,
Each α-particle energy moderator material piece is irradiated with α-particles from the α-ray source 3 to generate an α-ray continuous energy distribution, and this is irradiated to the semiconductor device 1 under test.

When the malfunction check device 7 detects a malfunction of the semiconductor device under test 1, it sends a malfunction occurrence signal to the film thickness detection means 8. On the other hand, the film thickness detecting means 8 always receives a signal from the photomicrosensor 6 corresponding to the film thickness of the α particle energy moderator material piece. As shown in FIG. 3, the signals at this time are received as pulse trains 20 to 27 in the same number as the holes 12 to 19 for detecting the photomicrosensor. Then, in synchronization with the malfunction occurrence signal, the film thickness when the malfunction is generated is determined, and the result is sent to the tester means 9, and the film thickness of the α particle energy moderator material is converted into the incident α particle energy value. Convert and test for malfunction.

In this embodiment, as the means for detecting the film thickness of the α particle energy moderator material piece, holes 12 to 19 for photomicrosensor detection are provided for each α particle energy moderator material piece, but this hole The number may be one. Also, instead of holes, α
The rotation angle of the particle energy moderator 4 may be read by a rotary encoder to detect the film thickness of the α particle energy moderator piece, or other means may be used.

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

〔The invention's effect〕

According to the present invention described above, the thickness detecting means for detecting the thickness of the radiation energy moderator material piece through which the radiation has passed when the semiconductor device malfunctions, and the radiation energy moderating input from the thickness detecting means. By configuring by providing the energy conversion means of incident radiation for converting the incident radiation energy value from the thickness of the material piece, it is possible to simultaneously measure the accelerated life evaluation test of malfunction and the α particle energy dependence characteristic, There is an effect that the characteristic evaluation time of the semiconductor device under test can be significantly shortened as compared with the prior art.

[Brief description of drawings]

FIG. 1 is a vertical sectional front view showing an embodiment of the test apparatus of the present invention,
2 is a plan view of the radiation energy moderator of the test apparatus shown in FIG. 1, FIG. 3 is a diagram showing a pulse train obtained from the photomicrosensor of the test apparatus shown in FIG. 1, and FIG. FIG. 5 is a diagram showing an α-particle energy dependence characteristic of the semiconductor device, and FIG. 5 is a diagram showing an α-particle energy distribution when the film thickness of the α-particle energy moderator piece is used as a parameter. 1 ... Semiconductor device under test, 3 ... α-ray source, 4 ... α particle energy moderator, t _{0 to} t ₇ ... α particle energy moderator part, 6 ... Photomicrosensor, 8 ... Membrane Thickness detection means.

Claims (1)

[Claims] 1. A disk-shaped radiation energy is provided in which a radiation source and a semiconductor device under test are arranged in a vacuum chamber, and a plurality of radiation energy moderator material pieces are provided on the same rotation plane between them. A test for testing malfunction of a semiconductor device by forming a water-reducing material, rotating the radiation energy moderator, passing radiation from a radiation source through the rotated radiation energy moderator, and causing the radiation to enter the semiconductor device under test. In the device, a thickness detecting means for detecting the thickness of the radiation energy moderator material piece through which radiation has passed when a malfunction of the semiconductor device occurs, and the thickness of the radiation energy moderator material piece input from the thickness detecting means. An incident radiation energy conversion means for converting the energy value of incident radiation is provided, and a semiconductor device test apparatus is provided.