RU2253125C1 - Method for detecting potentially unstable transistors - Google Patents

Abstract

FIELD: micro-electronics industry.

SUBSTANCE: method includes, after prior results of test for each transistor type, performing stability tests in constant mode of current amplification coefficient measurement during 20-30 minutes, results of which are used to estimate transistor stability.

EFFECT: shortened test time with no effect from stress density current.

4 tbl

Description

The invention relates to microelectronics, and in particular to ensuring the quality and reliability of transistors by identifying potentially unstable transistors. The invention can be used at the stage of serial production of semiconductor products, as well as at the input control in the manufacture of radio equipment.

The closest analogue is the method [1] used to split the batch of transistors, which consists in the fact that the transistors in the process of testing are affected by a high-density current pulse and reject the transistors according to the magnitude of the leakage currents. The disadvantages of this method: the need to test devices with a current of stress density, leading to a decrease in the reliability of the tested transistors, and a long test time.

The invention is aimed at eliminating these disadvantages, namely: in the proposed method there is no exposure to current stress density, and the test time is significantly reduced.

This is achieved by the fact that in the proposed method for determining potentially unstable transistors, the measurements of the leakage currents before and after the tests are replaced by repeated measurement of the current gain h _21e during the tests.

The method is as follows. In the process of testing transistors, ten-fold measurements of the current gain are carried out after 2 minutes for low-power and medium-power transistors and after 5 minutes for high-power transistors. If the gain h _21e during these measurements is stable with an accuracy of ± 2 units, then tests are carried out in the control mode h _21e for 20-30 minutes with regular fixing of the value h _21e , which is used to judge the stability of transistors. For each type of transistor, a stability criterion is pre-set according to the parameter h _21e during testing.

, представлен в табл.4.As an example, we give the implementation of this method on batches of transistors of the type KT209E (low power), KT814G (medium power) and KT819G (powerful). At the first stage, all transistors with ten-fold sequential measurement of the parameter h _21e have stable values (within ± 2 units). At the second stage, transistors were tested for 20 minutes and the data are presented in Tables 1-3. The coefficient of stability of the values of the parameter h _21e , determined from the formula

is presented in table 4.

Table 1 No. The value of h _21e for transistors of the type KT209E with a constant measurement mode through 0 5 minutes 10 minutes 15 minutes 20 minutes 1 210 175 210 210 175 2 175 175 175 175 175 3 170 170 170 170 170 4 200 200 200 200 200 5 145 145 145 145 145 6 220 220 220 220 220 7 165 165 200 200 200 8 185 185 188 185 185 table 2 No. The value of h _{21e for KT814G} type transistors with a constant measurement mode through 0 5 minutes 10 minutes 15 minutes 20 minutes 1 250 Renouncement 2 350 350 430 466 466 3 460 460 560 620 620 4 560 466 620 700 620 5 350 Renouncement 6 466 466 466 466 466 7 450 400 450 560 560 8 440 440 545 545 545 Table 3 No. The value of h _21e transistors of the type KT819G with a constant measurement mode through 0 5 minutes 10 minutes 15 minutes 20 minutes 1 138 140 138 138 138 2 104 105 104 104 104 3 130 130 130 130 130 4 135 135 135 135 135 5 137 137 137 137 137 6 114 114 114 110 110 7 117 117 117 117 117 8 108 108 108 106 108

Table 4 No. Instability coefficient k for transistors of the type KT209E KT814G KT819G 1 0.83 Renouncement 1 2 1 1.33 1 3 1 1.34 1 4 1 1.25-1.1 1 5 1 Renouncement 1 6 1 1 0.96 7 1,2 1,2 1 8 1 1.23 1

From the table. Figure 4 shows that for KT209E transistors, k = 1.0 can be set; for KT814G transistors - k = 1.25; for transistors like KT819r - k = 1,0.

It is seen that the KT814G type transistors have the least stability and there are catastrophic failures during the tests. Apparently, the batch of transistors from which the sample was taken did not pass the ETT in the process of mass production.

SOURCES OF INFORMATION

1. RF patent No. 2098839 C2, G 01 R 31/26, 31/28, 1997.

2. Gorlov M.I., Anufriev L.N., Bordyuzha O.L. Ensuring and improving the reliability of semiconductor devices and integrated circuits in the process of mass production - Minsk: Integral, 1997, 390 p.

Claims (1)

A method for determining potentially unstable transistors, which consists in measuring the current gain, characterized in that after preliminary test results for each type of transistor, stability tests are carried out in a constant mode of measuring the current gain for 20-30 minutes, according to the results of which transistor stability.