RU2561337C1 - Method of measurement of heat resistance of cmos of digital integrated chips - Google Patents

Abstract

FIELD: instrumentation.

SUBSTANCE: method comprises supply of voltage to the tested chip, switching of a logical state of a heating logical element by sequence of periodic impulses, measurement of change of the temperature sensitive parameter, determination of heat resistance, note that the heating logical element is switched by highly sensitive impulses, and the temperature sensitive parameter is the period of sequence of the low-frequency impulses generated by the multivibrator, and the multivibrator consists of a logical element of the tested chip and the logical element of the reference chip operated together with passive elements of the multivibrator at constant temperature.

EFFECT: possibility of shortening time of measurement and error of measurement of temperature sensitive parameter.

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Description

The invention relates to measuring equipment and can be used to control the quality of digital integrated circuits with CMOS logic elements (LEs) and assess their temperature reserves.

A known method of measuring the thermal resistance of digital integrated circuits RT, in which the chip is heated by switching frequency-modulated pulses of the LE selected as a heat source, measure the change in temperature-sensitive parameter (TCH) of the LE selected as a temperature sensor, determine the heating power and determine the thermal resistance with using the measured changes in the PMP, heating power and the known temperature coefficient of the PMP (see AS 1310754 of the USSR. Method for measuring thermal resistance transition-case of digital integrated circuits / V. A. Sergeev, G. F. Afanasyev, B. N. Romanov, V. V. Yudin. Publish. 05.15.87. Bull. No. 18). The voltage of the logic unit at the output of the LE is used as a PST.

The disadvantage of this method is the large time of measuring the voltage of the PPP by a selective voltmeter, which limits the automation of the control of thermal resistance of microcircuits in mass production.

The closest method of the same purpose to the claimed invention from the totality of features is a method for determining the thermal resistance of digital integrated circuits, in which a heating element selected as a heat source is heated by applying high-frequency switching pulses modulated by a sequence of low-frequency pulses in the form of a meander to its input, determine heating power, measure the change in the PMI of the LE selected as a temperature sensor, and determine the thermal resistance from the measured mu change in PMP, heating power and the known temperature coefficient of PMP (see patent No. 2463618. Method for determining the thermal impedance of CMOS digital integrated circuits / Sergeev VA, Lamzin VA, Yudin VV Publ. 10.10.2012) adopted for the prototype.

The disadvantage of this method, adopted as a prototype, is also a large time for measuring the voltage of the PMT by a selective voltmeter and a large error in measuring the PMT.

The technical result is to reduce the measurement time and the measurement error of the PPP.

The specified technical result in the implementation of the invention is achieved by the fact that in the known method for measuring the thermal resistance of CMOS digital integrated circuits, including switching the logical state of the heating logic element by a sequence of high-frequency pulses, determining heating power, measuring the change in the temperature-sensitive parameter, calculating the thermal resistance as the ratio of the measured change in the temperature-sensitive parameter to heating power and temperature mu coefficient of the temperature-sensitive parameter, the peculiarity lies in the fact that the length of the repetition period of the low-frequency pulses generated by the multivibrator is used as the temperature-sensitive parameter, and the multivibrator consists of a logical element of a controlled microcircuit and a logical element of a reference microcircuit working together with passive elements of the multivibrator at a constant temperature, and temperature coefficient of the duration of the low-frequency impu lys is determined by heating in a thermostat a controlled microcircuit while maintaining a constant temperature of the model microcircuit with passive elements.

The invention consists in the following. CMOS heating of digital integrated circuits is carried out by supplying one LE selected as a heat source, high-frequency switching pulses to the input (see, for example, Till, U. Integrated circuits. Materials, devices, manufacturing: translation from English / U. Till, J. Laxon. - M.: Mir, 1985 .-- pp. 474-475). The heating power is determined from the expression

- напряжение питания контролируемой микросхемы; f - частота следования высокочастотных импульсов греющегося ЛЭ; С_н - емкость нагрузки греющегося ЛЭ.Where

- supply voltage of the controlled microcircuit; f is the repetition rate of high-frequency pulses of the heating LE; With _n - load capacity of the heating LE.

Due to thermal conductivity, heat is transferred to other elements of the microcircuit and changes their electrical characteristics. The thermal connection between the LEs in digital integrated circuits is used to determine the thermal resistance (see Zaks D. I. Parameters of the thermal regime of semiconductor microcircuits. M: Radio and communication, 1983, p.31-32). Setting the increment of electric power ΔP of the heating LE, measure the change in the PM of the LE used as a temperature sensor. Thermal resistance R _T is determined by the formula:

where Δθ is the temperature increment of the LE used as a temperature sensor; K _U is the temperature coefficient of the PMT.

, чувствительное к изменению напряжения питания ЛЭ. Микросхема в прототипе находится в двух разделенных по времени последовательно чередующихся состояниях: в состоянии нагрева и в состоянии измерения

. Каждому состоянию соответствует свое напряжение питания ЛЭ, выбранного в качестве датчика температуры. В состоянии измерения

напряжение питания повышается скачком относительно напряжения питания в состоянии нагрева на величину падения напряжения тока нагрева на паразитном сопротивлении в цепи питания ΔU_эл. Напряжение

также увеличивается. Скачкообразное изменение напряжения

за счет влияния электрической связи ΔU_эл алгебраически складывается с приращением напряжения

спадающего у КМОП микросхем по экспоненте, за счет влияния тепловой связи, что значительно увеличивает погрешность измерения ТЧП.In addition to the thermal connection between the LEs, there is an electrical connection due to the presence of parasitic resistance of the common power supply bus of the logic elements of the microcircuit (see, for example, AS No. 1613978 authors Sergeyev V.A., Yudin V.V., Goryunov HH "Measurement method thermal resistance of digital integrated circuits and a device for its implementation ", publ. 15.12.90. Bull. No. 46). In the prototype, the voltage of a logical unit is used as a PMT

sensitive to changes in the power supply voltage LE. The microcircuit in the prototype is in two time-sequentially alternating states: in a heating state and in a measuring state

. Each state has its own power supply voltage of the LE selected as a temperature sensor. In the state of measurement

the supply voltage rises abruptly relative to the supply voltage in the heating state by the magnitude of the drop in the heating current voltage at the parasitic resistance in the supply circuit ΔU _el Voltage

also increasing. Sudden voltage change

due to the influence of electrical coupling, ΔU _el algebraically adds up with a voltage increment

CMOS chips decaying exponentially due to the influence of thermal coupling, which significantly increases the error in measuring the PMT.

, выбранного в качестве ТЧП, на низкой частоте при длительности периода следования Т_нч>>τ и на высокой частоте при Т_вч<<τ, где τ - тепловая постоянная времени кристалла микросхемы. При Т_вч<<τ изменение напряжения

обусловлено только влиянием электрической составляющей ΔU_эл. Истинную величину

обусловленную только изменением за счет тепловой связи, определяют путем вычитания

(см., например, Аронов В.Л., Федотов Я.А. Испытание и исследование полупроводниковых приборов. Учебн. пособие для специальностей полупроводниковой техники вузов, М., «Высшая школа», 1975, стр.246). Двойное измерение

на двух частотах увеличивает время измерения.In practice, the electrical component is excluded by measuring AC voltage

, selected as a PST, at a low frequency for a duration of the repetition period T _LF >> τ and at a high frequency for T _HF << τ, where τ is the thermal time constant of the chip of the chip. At T _rf << τ, the voltage change

due only to the influence of the electrical component ΔU _el . True value

due only to a change due to thermal bonding, is determined by subtracting

(see, for example, Aronov V.L., Fedotov Y.A. Testing and research of semiconductor devices. Textbook for specialties of semiconductor technology of universities, M., "Higher School", 1975, p.246). Double dimension

at two frequencies increases the measurement time.

и падение напряжения U_рп на защитном диоде логического элемента ЛЭ1. Изменение напряжений ЛЭ1 преобразуется в изменение частоты колебаний U_м мультивибратора. Длительность периода колебания Т мультивибратора имеет вид (см., например, Зельдин Е.А. Импульсные устройства на микросхемах. - М.: Радио и связь, 1991. - стр.84-85):To eliminate the error in the measurement of the PMT introduced by the electrical connection between the LEs and to reduce the time of measuring the thermal resistance, we choose as the PMP the duration of the period T of the low-frequency oscillations of a multivibrator with one timing RC circuit. One arm of the multivibrator is LE1 of the controlled microcircuit 1, selected as a temperature sensor. The second shoulder is the LE2 of the exemplary microcircuit 2, the temperature of which, together with the external timing RC circuit, remains constant during the measurement process (see Fig. 1). One LE controlled chip selected as a heat source is heated by high-frequency switching pulses U _HF (see FIG. 2 a). To enhance heating, the output of the LE is loaded onto the load capacitance C _n . Selecting the load capacitance from the condition C _n >> C _o , where C _o is the internal capacitance at the output of the LE, the heating power, determined by formula (1), will be the same for all microcircuits. In the process of heating the controlled microcircuit, a change in the threshold voltage U _pore switching voltage

and the voltage drop U _RP on the protective diode of the logic element LE1. The change in voltage LE1 is converted into a change in the oscillation frequency U _{m of the} multivibrator. The duration of the oscillation period T of the multivibrator has the form (see, for example, Zeldin E.A. Pulse devices on microcircuits. - M .: Radio and communications, 1991. - pp. 84-85):

The measurement of the duration of the repetition period of low-frequency pulses T is carried out at the beginning of the time of the heating cycle t _c (see fig.2d) - T ₁ , and at the end of the heating cycle - T _m . The heating cycle time is set by the heating cycle signal U _c , as shown in FIG. The increment of the following period is calculated:

and thermal resistance according to the formula (2).

, входящее в формулу (3), изменяться скачком не будут из-за отсутствия изменения напряжения на паразитном сопротивлении контролируемой микросхемы 1. Погрешность измерения ТЧП при этом существенно уменьшается.With this sequence of measurement of the repetition period of low-frequency pulses, when both heating and measurement are carried out simultaneously, the supply voltage LE1 and voltage

, included in the formula (3), will not change abruptly due to the absence of a change in voltage at the parasitic resistance of the controlled microcircuit 1. The error in measuring the PPI decreases significantly.

Let us evaluate the methodological error due to the heating of the controlled microcircuit 1 for the first pulse repetition period. We accept the exponential law of the change in the temperature of heating. The temperature increment for the first period of the multivibrator pulse Δθ ₁ and at the end of the heating cycle Δθ _c will be:

where T ₁ - the duration of the first period of the pulses of the multivibrator; t _c - the duration of the heating cycle; τ is the thermal time constant of the chip chip. The methodical measurement error δ will be equal to:

In this case, the inequality T ₁ << τ << t _c should be satisfied. For microcircuits of medium degree of integration, the error δ does not exceed 1%.

, выбранного в прототипе в качестве ТЧП.The error and time of measuring the duration of the period T is much less than the error and time of voltage measurement

selected in the prototype as a PMT.

The temperature coefficient of the duration of the period K _t is determined by heating in a thermostat a controlled microcircuit 1 while maintaining a constant temperature of the model microcircuit 2 with passive elements (RC timing circuit).

Figure 1 presents the meter that implements a method for determining the thermal resistance of CMOS digital integrated circuits.

Figure 2 presents the voltage diagram of a circuit that implements a method for determining the thermal resistance of CMOS digital integrated circuits.

The meter contains the studied microcircuit 1, the exemplary microcircuit 2, the power supply 3 of the investigated and exemplary microcircuits, the generator of high-frequency heating pulses 4, the first driver 5 of the start pulse, trigger 6, the first logic element 2I 7, inverter 8, register 9, the second logic element 2I 10 , the third logic element 2I 11, the generator of the counting pulses 12, the first counter 13, the second counter 14, the subtractor 15, the second driver 16 of the reset pulses, the fourth logic element 2I 17.

The meter works as follows. In the initial state, the controlled microcircuit 1 and the exemplary microcircuit 2 are connected to a common power source 3 (see figure 1). At the output of the trigger 6 immediately after turning on the power of the meter there is an arbitrary level of logical voltage. The operation of the circuit begins with the supply of a start pulse U _{f1 of a} low logic level (see Fig. 2b) from a pulse shaper 5 to the reset input of trigger 6 through logic element 2I 6, to the input of reset of register 9 and counters 14 and 15. At the same time, at the output of the trigger 6 and at the first output of register 9, the logic zero level is set, the counters 13 and 14 are reset. The logic zero level at the output of trigger 6 blocks the first logic element 2I 7 and the logic element LE2 of the model microcircuit 2 in the multivibrator. After the expiration time of the start pulse U _f1 on its trailing edge at the output of the trigger 6 (Fig.2B) and the first output of the register 9 (Fig.2E), the logical unit levels U _c and U _{p1 are set} . 2I logic circuit 7 transmits the high frequency pulses U _HF (2 a) with a high-frequency generator 4 heating pulses at the LE input selected as a heat source controlled chip 1. multivibrators controlled logic elements LE1 LE2 chip 1 and chip 2 model begins to generate low-frequency pulses U _m (fig.2d). The generated pulses of the multivibrator are removed from LE2. The first period of low-frequency pulses T ₁ begins with a low logic level. As a result of heating the controlled microcircuit, its temperature increases exponentially, as shown in Fig. 2d, and the duration T _{i of the} low-frequency pulses generated by the multivibrator increases with constant values of the resistance R and capacitance C of the timing circuit. The generated pulses of the multivibrator are inverted by the inverter 8 and shift the level of the logic unit at the outputs of the register 9. Prior to the second pulse of the multivibrator from the LE2 to the input of the register 9, the pulses of the generator 12 of the counting pulses U _cf are fed through the second logic element 2I 10 to the input of the first counter 13 (fig.2z ) and the number of transmitted pulses is recorded. This time corresponds to the start of heating of the controlled microcircuit 1. In the future, the pulses of the multivibrator of the logical unit shift at the output of the register to the selected bit m. The last m pulse of the register 9 U _pm (Fig.2zh) allows the passage of counting pulses from the generator 12 through the third logic element 2I 11 to the input of the counter 14 (Fig.2z) and the number of pulses of the "hot" controlled chip 1 is also recorded repetition period T _m . Subtractor 15 calculates the difference Δn of the pulses recorded in the counters 13 and 14. With the arrival of the next multivibrator pulse, the second driver 16 generates a pulse U _ф2 with a logic zero level (Fig. 2i), which completes the total cycle time t _{c of the} measurement (Fig. 2c) by resetting trigger 6 through the fourth logic element 2and 17.

The increment of the duration of the pulse repetition period ΔT = T _m -T ₁ = Δn · τ _scc , where τ _scc is the length of the repetition period of the counted pulses U _cc . Thermal resistance is determined by the formula (2)

R _T = ΔT / K _T ΔP,

where K _T is the known temperature coefficient of the duration of the multivibrator repetition period.

Claims (1)

A method of measuring the thermal resistance of CMOS digital integrated circuits, including applying voltage to the controlled microcircuit, switching the logical state of the heating logic element by a sequence of periodic pulses, measuring the change in the temperature-sensitive parameter, determining the thermal resistance using the measured change in the temperature-sensitive parameter, heating power and temperature coefficient of the temperature-sensitive parameter, different the fact that the cutting logic element is switched by high-frequency pulses, and as the temperature-sensitive parameter, the length of the period of repetition of low-frequency pulses generated by the multivibrator is used, and the multivibrator consists of a logic element of a controlled microcircuit and a logical element of a model microcircuit working together with passive elements of the multivibrator at a constant temperature, and the temperature coefficient of duration the period of repetition of low-frequency pulses is determined by by heating in a thermostat of a controlled microcircuit while maintaining a constant temperature of an exemplary microcircuit with passive elements.

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