Showing papers on "Junction temperature published in 1992"

Determination of junction temperature in AlGaAs/GaAs heterojunction bipolar transistors by electrical measurement

Abstract: A method of measuring the junction temperature and associated thermal resistance of heterojunction bipolar transistors by using the temperature dependence of the DC gain is described. >

Temperature distribution in Si-MOSFETs studied by micro-Raman spectroscopy

Abstract: The local rise of lattice temperature in n-MOSFETs is analyzed by the energy shift of the silicon optical phonon using Raman spectroscopy with submicrometer spatial resolution. When operating the devices in saturation, a source-drain temperature asymmetry is observed corresponding to the heat dissipation profile that peaks in the pinch-off region. In the substrate surrounding the transistor an anisotropic temperature distribution is found which is related to the geometric shape of the heat source. A reduction of channel length under standard conditions leads to a local temperature increase due to the higher power density. The authors found temperature increases of less than 20 K for an operating voltage of 5 V for a channel length down to 0.3 mu m. The time constant of transient heating under pulse operation is determined by analyzing the inhomogeneous broadening of the Raman line. Thermal time constants of about 200 ns are obtained. >

Temperature rise and thermal rise‐time measurements of a semiconductor laser diode

Abstract: A novel method is presented for measurement of the rise in temperature and thermal rise time of a semiconductor laser diode (LD) under pulsed operation. The technique employs the shift in LD threshold current which occurs with a rise in junction temperature. Practical results are given, showing a rise time of about 10 ns.

Adding a heat bypass improves the thermal characteristics of a 50 μm spaced 8‐beam laser diode array

Abstract: Because heat transferred between closely spaced elements in a compact laser diode array shortens array lifetime and affects the elements’ operating characteristics, we evaluated the effect of a heat‐bypass structure by measuring the thermal resistance of array elements. We estimated thermal resistance by measuring differences between junction voltage before and after injecting subthreshold current pulses. The thermal resistances due to self heating were more than 20% lower after adding the heat‐bypass structure. This effect was greatest for elements whose thermal resistance was initially highest, and it was proportional to the number of operating elements. The bypass structure therefore also reduced the thermal resistance resulting from simultaneous operation of all eight elements by more than 40%. The resultant reduction in the junction temperature of array elements operating at 100 mW would increase array lifetime at least threefold.

Method of measuring junction temperature

Abstract: The present invention relates to a method of measuring junction temperature of a diode junction within a semiconductor device. The method has the steps of measuring current/voltage characteristics for various diodes at room temperature, determining an ideal factor for each diode, changing the temperature of the diodes to a selected temperature, remeasuring current/voltage characteristics for each diode, and comparing the measurements that have been made so as to obtain a temperature coefficients. The method also has the steps of measuring, at room temperature, a current/voltage characteristic of a diode to be utilized, determining an ideal factor from the measured current/voltage characteristic, determining a temperature coefficient corresponding to the ideal factor of by performing a linear interprelation between the ideal factors obtained for the various diodes, the ideal factor obtained for the diode, and the temperature coefficients of the various diodes, placing the diode where it will be used, measuring the current/voltage characteristic of the diode, determining the junction temperature of the diode from the temperature coefficient of the various diodes, the current/voltage characteristic of the diode at room temperature and where it will be used.

Direct-immersion cooling for high power electronic chips

Abstract: Several direct-immersion cooling techniques currently under examination are reviewed. They include cooling by means of pool boiling, falling films, channel flow boiling, and jet impingement. Both thermal performance and practical packaging concerns are discussed, and the suitability of each technique for dissipating high heat fluxes from isolated chips and multichip modules is assessed with respect to such considerations as chip junction temperature, cooling uniformity, and critical heat flux (CHF). It is shown that several means are available for greatly increasing CHF in order to satisfy the cooling requirements for future electronic devices. While high cooling fluxes are possible with a number of direct-immersion cooling techniques, the complexity of the coolant conditioning and delivery to the chips should be carefully considered in selecting a suitable cooling technique. >

Semiconductor surface resistivity probe with semiconductor temperature control

Abstract: The resistivity of the surface of a semiconductor wafer is measured at different temperatures to determine the resistivity as a function of temperature. The temperature of the semiconductor wafer is varied by a heater in thermal contact with the semiconductor wafer, and the temperature is measured by a temperature sensor in thermal contact with the semiconductor. The heater is controlled by a control unit which adjusts the amount of heat provided by the heater, thereby controlling the temperature at which a measurement from a four-point resistivity probe is taken.

Electrical measurement of the junction temperature of an RF power transistor

Abstract: An enhanced electrical method is presented for measuring the average junction temperature of an RF bipolar transistor. A two-step procedure, previously developed for DC operation, is extended to include the junction temperature measurement for an RF power transistor in a tuned amplifier circuit. The measurement technique is convenient, since it can be used with normal, packaged devices, and does not require a complex heat flow model or ambient temperature measurements. >

Two-dimensional thermal modeling of power monolithic microwave integrated circuits (MMICs)

Abstract: Numerical simulations of the two-dimensional temperature distribution for a typical GaAs MMIC circuit were conducted in order to understand the heat conduction process of the circuit chip and to provide temperature information for device reliability analysis. The method used is to solve the two-dimensional heat conduction equation with a control-volume-based finite difference scheme. In particular, the effects of the power dissipation and the ambient temperature are examined, and the criterion for the worst operating environment is discussed in terms of the allowed highest device junction temperature. >

Development and application of test chips and test systems for the thermal characteristics of IC packaging technologies

Abstract: The authors report on the development and application of test chips and computerized test systems for the steady state and transient thermal characterization of IC packaging technologies. The steady state test system is discussed in terms of the temperature sensor calibration algorithm and the error budget associated with junction-to-case thermal resistance measurements in an oven environment. Accuracy and repeatability figures of +or-18% and +or-4% respectively have been obtained for an oven-based junction-to-case thermal resistance test method. By a comparison with infrared thermal imaging, the use of the average junction temperature is shown to provide an accurate thermal resistance figure for conventional IC package structures. >

Compensation type heat sensor

Abstract: A pair of temperature detection devices having different heat time constants and an active device having a predetermined bias are connected in series. The bias is set so as to cause the active device to operate in a saturated region if the temperature is higher than a dangerous level, and to operate in a triode region if the temperature is lower than the dangerous level. The temperature detection devices are chosen so as to cause the voltage generated at the junction of the temperature detection devices to be higher than a predetermined reference voltage if the temperature has been raised to the dangerous level when the temperature is raised slowly, or if the temperature is raised rapidly, even if the temperature is lower than the dangerous level. A constant temperature function and a differential function are generated to detect that a fire has taken place. In another embodiment, one of the temperature detection devices (in series with an active device) is arranged in parallel with the other temperature detection device (in series with a resistor). The relative voltages of the two temperature detection devices are monitored to detect a "too high" or "too rapidly increasing" temperature. The resultant compensation type heat sensor has a reduced number of elements, the cost of which can be reduced and which possess both the constant temperature function and the differential function.

Development and analysis of an automated test system for the thermal characterization of IC packaging technologies

Abstract: The development of an automated test system for the thermal characterization of IC packages is reported. A range of thermal test chips which have also been developed is described. The thermal test system is discussed in detail in terms of the temperature sensor calibration algorithm and the error budget associated with junction-to-case thermal resistance measurements in an oven environment. A detailed discussion of the experimental errors and uncertainties is presented. A figure of +or-4% has been obtained for both the accuracy and repeatability of an oven-based junction-to-case thermal resistance test method. This is shown to compare favorably with the performance of a temperature controlled heat sink system. By comparison with infrared thermal imaging, the measurement of the average chip junction temperature is shown to provide an accurate thermal resistance figure for conventional IC package structures. IC packages used to demonstrate the application of the test system and test chips to thermal characterization include DIPs, PGAs, and chip carriers. >

Estimating the temperature rise of power MOSFETs during the UIS test

Abstract: A method for determining the temperature rise of a power MOSFET during an unclamped inductive switching (UIS) test is described. The procedure consists of the following steps: breakdown voltage avalanche resistance measurement, breakdown voltage temperature coefficient calibration, and voltage waveform monitoring during the UIS test. A first-order model of the voltage waveform allows the computation of the junction temperature rise due to self-heating during a high-energy, long-pulse UIS test. The estimations are compared with those obtained based on the thermal impedance concept. >

Thermopile type infrared sensor and its manufacture

Abstract: PURPOSE:To get a highly sensitive and small sensor by mounting a film thermistor for measuring the temperature of a cold junction on a thermopile type infrared sensor thereby enabling always accurate cold junction temperature to be measured no matter how the temperature of the cold junction changes. CONSTITUTION:The thermopile type infrared sensor, which is equipped with a pit part 4 provided in a substrate 1, a lower insulating film 51 provided on this substrate, a film thermistor 3 provided above this lower insulating film and besides at the heat sink of the substrate, a comb-shaped thermistor electrode 31 provided on this film thermistor, and a thermopile 70 having a cold junction 71 and a hot junction 72, and its manufacture.

Burn-in apparatus and method for semiconductor devices

Abstract: A burn-in apparatus used in burn-in tests includes a burn-in test chamber for accommodating a plurality of semiconductor devices to be tested. Also, the burn-in apparatus includes measuring devices for detecting electric characteristics of temperature sensors built in the respective semiconductor devices to individually measure junction temperatures of the semiconductor chips incorporated in the respective semiconductor devices, and laser beam irradiating mechanisms or electric heating members. The laser irradiating mechanisms or the heating members are controlled by control units, based on outputs of the measuring devices. Thus, the junction temperatures are maintained in a set junction temperature range, and the screening accuracy can be improved.

Nonisothermal drift-diffusion model of avalanche diodes

Abstract: A nonisothermal drift‐diffusion model of avalanche diodes is described. The novel feature of the model is the inclusion of the heat conduction equation in the basic set of semiconductor equations. The influence of a nonuniform temperature distribution across the active region on the diode electrical characteristics is investigated and the usual assumption of constant diode junction temperature is evaluated. Both single‐drift and double‐drift diodes are simulated. The temperature distribution is calculated as a function of the dc bias current density and the amplitude of the rf driving voltage. The diode impedance is also determined and compared with results from an isothermal simulation. Numerical results are presented at J‐(10–20 GHz) and W‐band frequencies (75–110 GHz).

Temperature detecting system for electronic device

Abstract: PURPOSE:To obtain a temperature detecting system for electronic devices which can economically detect the junction temperature of integrated circuit elements mounted on a substrate by utilizing the temperature depending property of the forward voltage of a diode. CONSTITUTION:In this temperature detecting system for electronic devices which detects the junction temperatures of integrated circuit elements 20 mounted on a substrate 10 by utilizing the temperature depending property of the forward voltage of a diode 3 incorporated in a specific integrated circuit element 20 mounted on the same substrate 10, a constant-current circuit 4 which feeds the diode 3 with a fixed amount of current and a voltage detection circuit 5 which detects the forward voltage of the diode 3 are provided. In addition, a temperature detection circuit section 8 is constituted of an EEPROM 70 in which the correcting data of the temperature depending property of the diode 3 are recorded and a temperature conversion circuit 7 incorporating a microprocessor 80 which corrects the measurements of the forward voltage of the diode 3 based on the correcting data and converts the corrected measurements into temperature information.

Temperature measuring apparatus.

Abstract: A processing unit (102) can be connected to a series of different probes (112;130), each having different characteristics, the selection of a probe being dependent on the temperature measuring task to be performed. A first probe (112) has a thermocouple (108) and a second temperature sensor (122) to provide cold junction compensation. The hot junction (108) of the thermocouple is placed in the medium, the temperature of which is to be measured, and the unit (102) derives the temperature from the voltage generated and the cold junction temperature measured by the second sensor (122). Other probes (130) containing a thermistor or platinum resistance thermometer (132) can be attached to the unit (102) to provide non-thermocouple temperature measurements. Thus, the speed or accuracy of a temperature measurement can be optimised to account for different criteria by the use of different probes with the appropriate type of sensor.

Simulation study of peak junction temperature and power limitation of AlGaAs/GaAs HBTs under pulsed and CW operation

Abstract: The authors have used a 3-D transmission-line matrix (TLM) modeling method to study the junction temperature distribution and power limitation of device geometries with multiple embedded heat sources. Peak values of the junction temperature against the dissipated power density under both pulsed and CW operation are presented for a typical power AlGaAs/GaAs HBT structure. These data should facilitate the rapid determination of junction temperature for a given output power, which is of paramount importance in power device design. >

17.6% Conversion Efficiency At 60 GHz with IMPATT Diodes ?

Abstract: For the use in mobile systems high efficiency V-band IMPATT diodes for CW operation are developed. The design is based on a numerical large signal drift diffusion model. Flat-profile and low-high-low structures are simulated and the layers are grown by silicon molecular beam epitaxy. Solid circular and ring structures are fabricated. During the RF tests frequency dependent differences in the measured power levels using thermistor mounts and diode power sensors are observed: The RF tests yield a maximum efficiency of 17.6 % at 67 GHz with a double low-higlh-low diode measured with a manufacturer calibrated diode sensor. The efficiency drops to 13.5 % measured with a thermistor. With ring diodes high output powers (800 mW/59 GHz, no differences between different power sensors) at a very low junction temperature rise (140 K) can be obtained. At higher junction temperatures up to 1.4 Watt are achieved.

Dc static feeding system for electric rail way

Abstract: PURPOSE:To miniaturize a device and reduce production costs by making failure judgment according to the detected value of the current flowing a semiconductor circuit breaker and also extracting the critical breaker conductivity while calcu lating the junction temperature of semiconducting elements constituting the semiconducting circuit breaker based on the current CONSTITUTION:The AC voltage received through a transformer 1 is converted into DC voltage by a converter 2 and applied to a DC feeder 5 from a positive electrode bus 3 through a GTO circuit breaker 4 DC current is supplied from the DC feeder 5 to an electric vehicle 7 through a pantograph 6 In this case, the forward current and backward current of the GTO circuit breaker 4 are detected through current detectors 11 and 12 and waveform shaping circuits 13 and 14 and are led On the other hand, the current flow through the GTO circuit breaker 4 is detected by a current detector 16, and based on the resultant current value, failure discrimination is made by a failure selection device 17, and the result of the discrimination is sent to a loading state judging circuit 18 The loading state judging circuit 18 makes a required judgment based on the detected junction temperature and the above failure discrimination result

Joining method for turbine moving blade

Abstract: PURPOSE:To improve the strength reliability of a joined part by preventing the thermal deformation of the joined by part of a through joined a high temperature through a foil of an Ni base alloy containing a gamma' phase forming element between the joint surfaces of constitution parts of a turbine moving blade whose base metal is a gamma' precipitation strengthening type Ni base casting alloy. CONSTITUTION:Constitution parts 1, 2 are superposed through a foil 8 of an Ni base alloy containing a gamma' phase forming element between the joint surfaces, prescribed pressure force is loaded in a vacuum, the joined part is heated to a temperature at which diffused junction can be executed, from the outside periphery of the blade by a first heating source 9, and also, the non-joined part is heated to a lower temperature than a diffused junction temperature by a second heating source 10 provided in the outside periphery of the non-joined part and while controlling a temperature difference to the joined part to a prescribed temperature difference, the diffused junction is executed.

Method for measuring semiconductor junction temperature

Abstract: A method for measuring the temperature of a semiconductor junction without the temperature dependency of forward voltage. At the phase of preparation for measurement, the current and voltage of a diode are measured at the room temperature to obtain an ideal factor and forward voltage of the diode at the room temperature, and a temperature coefficient corresponding to the value of the ideal factor is obtained from a chart showing the relationship between the ideal factor and the temperature coefficient. Then, at the phase of measurement, forward voltage is measured by bringing the diode under actual operating conditions. The actual junction temperature is obtained from the forward voltages both at room temperature and under actual conditions and the temperature coefficient.

Integral heatsink polysilicon semiconductor packaging

Abstract: To evaluate some of the claims made in patent applications, UK 90 14491.6 and US 07/722,741 single-chip and multichip packages were fabricated from polycrystalline silicon (p:Si) with integral, p:Si, cooling fins. By using die-sized pieces of ceramic patterned with a platinum heater (of known temperature coefficient of resistance) data were recorded of heater temperature for a range of input wattages and different cooling conditions. The data are presented as heater temperature (corresponding to device junction temperature) above ambient, against a range of electrical input wattages for seven different package configurations cooled by convection and by forced air. Experimental results indicate that integral heatsink polycrystalline silicon packages for silicon semiconductor devices provide better thermal characteristics than existing ceramic packages. >

Measuring method of junction temperature

Abstract: PURPOSE:To provide a measuring method through which the junction temperature of a semiconductor device can be measured without actually measuring the temperature dependency of a forward voltage. CONSTITUTION:On a measurement preparatory phase, the current-voltage measurement of a diode is carried out at a room temperature, the ideal factor and the forward voltage of the diode are obtained at a room temperature, and a temperature coefficient correspondent to the ideal factor is obtained from a chart which indicates a relation between an ideal factor and a temperature coefficient. Furthermore, on a following main measurement phase, a diode is put under conditions where a junction temperature is actually measured, the forward voltage of the diode is measured, and then a junction temperature is obtained basing on the forward voltage concerned and the forward voltage previously obtained at a room temperature and the above temperature coefficient.

Evaluating method of reliability of semiconductor element

Abstract: PURPOSE:To make it possible to remove in a final process an element having a high possibility of being faulty initially, by determining a measured element as a good product when the change ratio of an interrupting current at an ordinary temperature to the one at a high temperature is within a set range. CONSTITUTION:A semiconductor element to be measured, e.g. a varicap diode 10, is conveyed to the position of interrupting-current measurers 12 along a conveyance route 11, and terminals 13 and 14 for ordinary-temperature or high- temperature measurement are connected to the opposite poles of the varicap diode 10. On the occasion of the high-temperature measurement by the interrupting-current measurers 12, a voltage-current is impressed so that the junction temperature of the varicap diode 10 to be measured may reach a prescribed operational temperature, and at this time, a power is kept to be fixed by adjustment by an actuation current, since nonuniformity exists for each element. According to this constitution, the semiconductor element to be measured which has a high possibility of being faulty initially can be removed in a final inspection process of manufacturing processes.

Semiconductor integrated circuit testing device

Abstract: PURPOSE:To prevent damage of a junction of an IC and damage of a contact surface of an IC chip of an IC cooler connector due to smoking by comparing a temperature characteristic signal corresponding to a temperature characteristic of a diode with a rated temperature value by an IC tester, and interrupting a test when the signal exceeds the value. CONSTITUTION:An IC tester 1 has a malfunction detector A50 for inputting a characteristic signal A corresponding to a junction temperature characteristic of a diode 29 and a rated temperature value B corresponding to a preset temperature, comparing them by a comparator 55, supplying an alarm output signal to a test controller 2 when the signal A exceeds the value B, and interrupting a test. For example, if an IC chip cannot be forcibly cooled, a voltage of an input A of the comparator 55 is varied upon rising of the temperature of the diode 29. If the voltage exceeds the value B, an alarm is generated from the comparator 55 to an alarm output line 53, it is received by the controller 2 of the tester 1 to immediately end the test.