RU2490656C2 - Method for sorting out of potentially unreliable transistors - Google Patents

Abstract

FIELD: electricity.

SUBSTANCE: coefficient of resistors amplification is measured in a common-emitter circuit at normal and high temperature. Absolute difference value Δ=h_21e100°C-h_21e20°C and values of relative change in amplification coefficient K= h_21e100°C/h_21e20°C are calculated for each transistor; h_21e100°C, h_21e20°C are values of amplification coefficient at high and normal temperature respectively. Transistors are sorted out when they meat two criteria simultaneously: Δ≥Δ_av; K≥K_av, where Δ_av and K_av are average values of absolute difference and relative change in retrieval for this type of transistors.

EFFECT: simplifying and enlarging functional capabilities.

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Description

The invention relates to microelectronics, and in particular to methods for ensuring the reliability of transistors and can be used to separate transistors according to reliability during the production process, as well as at input control at manufacturers of electronic equipment.

The known method [1] of separation of semiconductor products, including measuring the intensity of noise before and after external exposure, and the subsequent selection of potentially unreliable products is carried out by assessing the coefficients of increasing the noise intensity of each product after at least 10 thermal cycles in the range of permissible extreme temperatures compared to the initial values.

The disadvantage of this method is the additional measurement of the intensity of noise on special equipment.

The closest method is the method [2] for measuring the critical supply voltage (KNI) of integrated circuits at normal and elevated crystal temperatures, acceptable by technical conditions, and the selection of integrated circuits is carried out according to the relative magnitude of the change in KNI calculated by the formula:

$$\mathrm{TO}=\frac{E_{\mathrm{to}R.n\mathrm{about}Rm}}{E_{\mathrm{to}R.P\mathrm{about}\mathrm{at}}}-\mathrm{one}$$

where E _cr.norm , E _cr.pov - values of the critical supply voltage at normal and elevated temperatures, respectively.

The disadvantage of this method is the additional measurement of the critical supply voltage.

The present invention aims to eliminate this drawback and increase the functionality of the method.

The proposed method for rejecting potentially unreliable transistors is based on measuring the gain of the transistor in a circuit with a common emitter at normal and elevated (maximum permissible) temperatures. The absolute difference between the gain values at elevated and normal temperatures and the relative change in gain from temperature are determined. Reject transistors if they satisfy two criteria:

$$\Delta =h_{21E\mathrm{one\; hundred}°\mathrm{FROM}}-h_{21E\mathrm{twenty}°\mathrm{FROM}}\ge {\Delta }_{\mathrm{from}Redn}$$

$$\mathrm{TO}=\frac{h_{21E\mathrm{one\; hundred}°\mathrm{FROM}}}{h_{21E\mathrm{twenty}°\mathrm{FROM}}}\ge {\mathrm{TO}}_{\mathrm{from}Redn}$$

where h _{21Э100 ° C} , h _{21Э20 ° C} - gain values at elevated and normal temperatures, respectively; Δ _average - the average value of the absolute differences in the sample for a given type of transistor; K _average - the average value of the gain in the sample for a given type of transistor.

The method was tested on 11 transistors of the type KT 646 (silicon transistors of npn type, medium power). The gain of the transistor in the circuit with a common emitter is selected as an informative parameter. Values of h _21E at normal temperature (20 ° C) and elevated (100 ° C), absolute and relative changes in gain for each transistor, and average values of absolute and relative changes are shown in the table.

Table Transistor number h _21E at

$$\Delta =h_{21E\mathrm{one\; hundred}°\mathrm{FROM}}-h_{21E\mathrm{twenty}°\mathrm{FROM}}$$

$$\mathrm{TO}=\frac{h_{21E\mathrm{one\; hundred}°\mathrm{FROM}}}{h_{21E\mathrm{twenty}°\mathrm{FROM}}}$$

20 ° C 100 ° C one 76 150 74 1.97 2 one hundred 187 87 1.87 3 134 289 155 2.16 four 156 251 95 1,61 5 104 177 73 1.7 6 192 318 126 1.66 7 147 240 93 1,63 8 134 267 133 1.99 9 123 204 81 1.66 10 118 187 69 1,58 eleven 130 265 135 2.04 Δ _average = 102 K _average = 1.89

According to the first criterion, transistors No. 3, 6, 8, 11 will be potentially unreliable transistors; according to the second criterion - No. 1, 3, 8, 11. Thus, transistors No. 3, 8, 11 will be potentially unreliable, since they satisfy both criteria.

Information sources

1. RF patent No. 2289144, G01R 31/26, 2006.

2. RF patent No. 2365930, G01R 31/26, 2009.

Claims (1)

A method for rejecting potentially unreliable transistors, in accordance with which the gain of the transistors is measured in a circuit with a common emitter at normal and elevated temperatures, characterized in that for each transistor, the absolute difference of the gain at elevated and normal temperatures is first calculated by the formula Δ = h _{21E100 ° C} - h _{21E20 ° C,} and the value of the relative change of the gain of the temperature according to the formula K = h _{21E100 ° C:} h _{21E20 ° C,} where h _{21E100 ° C,} h _{21E20 ° C} - coefficient values Wuxi eniya at normal and elevated temperatures, and transistors discarded if they meet simultaneously two criteria: Δ≥Δ _average, K≥K _avg where Δ _avg - average value of the absolute difference and _{the average} K - average value of the relative change in the sample for this type transistors .