JP2000111416A - Method for measuring junction temperature and measuring apparatus for executing the method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately find a junction temperature, a package heat resistance by measuring a correct voltage in a forward direction of a PN junction in a method and an apparatus for measuring the junction temperature with using a TSP method. SOLUTION: A powering current is supplied for a predetermined time from a powering current source to a semiconductor device to be measured. After a predetermined time in which a temperature becomes a steady state has passed, a measurement current is supplied and a voltage in a forward direction of a PN junction is measured, whereby a temperature of the PN junction is found. In this method for measuring the junction temperature with using a TSP method, the measurement current is supplied slightly before the powering current is finished to be supplied. With the measurement temperature overlapping with the powering current, the voltage in the forward direction of the PN junction is started to be sample measured and a value obtained through the sampling immediately after passing a stop time point of the power impression is adopted as the measured value of the voltage in the forward direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor junction temperature measuring device for accurately measuring a device junction temperature in a target semiconductor integrated circuit device (ASIC and MCM).

[0002]

2. Description of the Related Art A method of measuring the thermal resistance of a semiconductor integrated circuit package is specified in SEMI Standard G38-87. This is because TSP (Temperature S)
The temperature is detected by an intrinsic parameter method. Specifically, the TSP method measures a semiconductor junction temperature using a forward voltage of a PN junction as an electrical parameter that is sensitive to device temperature.

The procedure of the method is as follows. Temperature calibration A device under test (DUT) is placed in a thermostatic chamber whose temperature can be set arbitrarily. After a sufficient time has passed for the chip temperature of the device to become equal to the temperature of the thermostatic chamber, the measurement current Is ( = Sense current) and measure the diode forward voltage Vf at the PN junction. By performing such measurement at a large number of sampling temperatures while changing the temperature of the thermostat, correlation data with the temperature of the diode forward voltage Vf of the PN junction is collected (calibration).

First, the device to be tested is stopped, and the forward voltage VMC is measured with the measurement current Is used in the calibration process of-. Next, immediately after the application of the power PH [W], the forward voltage VMH is measured with the measurement current Is used in the calibration process. The junction temperature Tj is calculated by the equation: Tj = Ta + (1 / k) ｛V _MH
-Calculated by V _MC ｝. Where Ta is the ambient temperature, k
Is the slope of the temperature correlation data graph of the TSP method obtained by-.

Accordingly, the package thermal resistance θ [° C./W] is
It can be calculated by the formula θ = (Tj−Ta) / P _H. Conventionally, switching from the application of power to the measurement current Is used in the calibration process has been performed manually or by a switcher (microcomputer control or several hundred ms by a MOS switch).

[0006]

It is possible to measure accurately by immediately switching to the measurement current Is used in the calibration process and immediately monitoring the forward voltage Vf immediately after the power is applied. Measurement error increases due to time. This is because when power application is stopped, T
This is because j decreases rapidly (eg, about 5 ° C./sec) and must be monitored promptly. Further, in a multi-chip module (MCM) in which a plurality of chips are mounted in one package, the same power consumption as in the actual operation cannot be applied because VDD is common, and therefore, the thermal resistance to be evaluated is different from that in the actual operation. . In other words, it is not known which power consumption was applied to which chip,
Unable to verify chip junction temperature.

The present invention relates to a method and an apparatus for measuring a PN junction temperature of a semiconductor device such as a substrate or a multi-chip module on which a single or a plurality of heating elements are mounted, and a method for measuring the temperature of the TSP.
An object of the present invention is to improve the method so that the junction temperature can be measured more accurately.

[0008]

According to a first aspect of the present invention, there is provided a method for measuring a junction temperature, wherein a predetermined current is applied between power supply terminals of a semiconductor integrated circuit to be measured, and the surface temperature of the semiconductor integrated circuit is reduced to a steady state. After the surface temperature is in a steady state, immediately before the predetermined current is cut off, a detection current sufficiently smaller than the predetermined current for measuring a junction temperature of the semiconductor integrated circuit is supplied to the power supply terminal, and the detection current is The junction temperature is measured based on the voltage between the power supply terminals when the current flows.

According to a second aspect of the present invention, there is provided a junction temperature measuring apparatus, comprising: a power application current source for supplying a specified power application current to a semiconductor integrated circuit to be measured; A voltage measuring means for supplying a measuring current sufficiently smaller than the applying current and measuring a forward voltage of the PN junction; and connecting the power applying current source to the semiconductor semiconductor integrated circuit for a predetermined time. Control means for controlling the supply period of the power application current and the supply period of the measurement current when connecting the measurement means, and a junction temperature and a forward voltage previously measured for the semiconductor semiconductor integrated circuit. And a table for holding the data representing the correlation of the above and a calculation for calculating the junction temperature by referring to the contents of the table from the measurement result of the voltage measuring means immediately after the supply of the power application current is stopped. Characterized by comprising a stage.

[0010]

In the junction temperature measuring method according to the present invention, a predetermined power is applied to the semiconductor integrated circuit to generate heat, and the application of the power is stopped after a time necessary to reach a thermal equilibrium state. The measurement of the forward voltage of the PN junction is started slightly before the stop time. Since the measured value of the forward voltage is significantly different before and after the time when the power application current stops, the data of the forward voltage of the PN junction by the measurement current can be easily identified, so that the earliest value after the power application is stopped The measurement value at the time is selected, and the joining temperature is calculated. If the application of power is stopped and switching to the measurement current is performed manually as in the prior art, the switching time takes at least one second, and only the measured value one second after the stop of power application is obtained. On the other hand, since the power application and the forward voltage measurement are partially overlapped as in the present invention, a measured value can be obtained immediately after the power application is stopped without a switching time.
For example, when the measured value of the forward voltage is extracted by sampling, sampling can be performed at a short interval (for example, 0.2 seconds or less), and a measured value within the sampling interval can be obtained at the maximum. FIG. 7 shows an example of the measurement time after the power application is stopped and the measured forward voltage. In this example, the forward voltage Vf is increased from 306 mV after 0.2 second to 315 mV after 1 second. To rise. When this is converted into the junction temperature Tj, Tj = 69 ° C. and 65 ° C., and there is a difference of 4 ° C. That is, by applying the present invention, the error can be reduced accordingly. As described above, according to the present invention, a more accurate bonding temperature can be obtained, so that an accurate package thermal resistance can be obtained. As a result, in the past, an extra margin was added to the measurement result with a large error to take an excessive heat dissipation measure.However, the present invention has enabled high-precision measurement, so that an appropriate heat dissipation measure can be taken. Cost can be reduced.

In the apparatus for carrying out the above method of the present invention, the power supply current source supplies a specified power application current to the semiconductor integrated circuit to be measured, and supplies the specified power to the semiconductor integrated circuit in a specified state. This produces an exotherm. The period of the application is a time required for the temperature of the integrated circuit to reach a steady state. The voltage measuring means supplies the semiconductor integrated circuit with a PN while supplying a measurement current sufficiently smaller than the power application current.
Measure the forward voltage of the junction. The control unit controls the supply period of the power application current and the supply period of the measurement current to partially overlap. The table holds data indicating the correlation between the junction temperature and the forward voltage measured in advance for the semiconductor integrated circuit. The calculation means refers to the contents of the table from the measured value of the forward voltage obtained after only the measurement current immediately after the supply of the power application current is stopped is supplied to the semiconductor integrated circuit and joins. Calculate the temperature. According to the present invention, since the end portion of the power application period and the start portion of the measurement current application period partially overlap, the power application period is changed from the power application period to the period in which the measurement current is applied as in the related art. Since no switching time is required, a forward voltage can be obtained quickly, and high-precision measurement is possible. As described above, according to the present invention, a more accurate bonding temperature can be obtained, so that an accurate package thermal resistance can be obtained. As a result, in the past, an extra margin was added to the measurement result with a large error to take an excessive heat dissipation measure.However, the present invention has enabled high-precision measurement, so that an appropriate heat dissipation measure can be taken. Cost can be reduced.

[0012]

FIG. 1 is a diagram showing an embodiment of a semiconductor junction temperature measuring apparatus according to the present invention. The semiconductor junction temperature measuring device 100 controls the device and controls the junction temperature Tj.
CPU 101 that performs calculation and other processing, a lookup table 102 that holds configuration data of Tj-Vf characteristics collected in advance, a timer 103 that controls power application time to a device to be measured, and a second relay from the output of the timer 103. An AND circuit 104 for generating a signal for controlling the ON start point of the 109; a delay circuit for delaying the output signal of the timer to control a period during which the first relay 107 and the second relay 109 overlap and are ON; 105, an inverter 106 for inverting the output of the delay circuit 105, a first relay 107 for controlling the connection of the power supply current source 108 to the device under measurement 120, and a first relay 107 for obtaining the temperature environment in use. A current source 108 for applying a power to supply a power load, 120
Current source 111 that supplies a measurement current Is to a voltage measurement unit 1 that detects a diode forward voltage Vf of a PN junction
12. It has a sampling section 113 for sampling the detected diode forward voltage Vf and digitizing it.

FIG. 2 shows a procedure of measurement using the measuring apparatus of the present embodiment having the above-described configuration. ,
First, Vf-Tj correlation data of a device to be measured, that is, calibration data is measured (step S1). There is no difference from what is performed in the above-mentioned conventional technology. That is, a device (DUT) to be tested is placed in a thermostat in which the temperature can be set arbitrarily, and after a sufficient time has passed for the chip temperature of the device to become equal to the temperature of the thermostat, the measured current Is (= (Sense current), and the diode forward voltage Vf at the PN junction is measured. By performing such a measurement at many sampling temperatures while changing the temperature of the thermostat, correlation data with the temperature of the diode forward voltage Vf of the PN junction is collected. FIG. 4 shows Vf-T
This shows one example of j correlation data, and the diode forward voltage Vf is inversely proportional to the junction temperature Tj. The collected Vf-Tj correlation data is stored in the memory 102 as a look-up table (step S2).

After the above preparations, the automatic measurement of the PN junction diode forward voltage Vj and the calculation of the junction temperature Tj are performed. That is, the measured current Is is supplied to the delay circuit 105.
Is set to overlap the power application current IF with the current (step S3). The overlap time is 0.
The time may be about 1 to 1 second. Next, the power application time is set in the timer 103 (step S4). In the timing chart of FIG. 5, the output signal of the timer 103 has a signal portion 51 which is at H level for a set time. The signal portion 51 is delayed by the delay circuit 105 and a signal 52 is output. The first relay 107 is turned on by the signal 53 inverted by the inverter 106. At time t1, the first relay 107 is turned on.

When the first relay 107 is turned on, the power application current IF flows between the power supply terminals VDD and VSS (or ground) of the device 120 to be measured (step S5). Specifically, this means that power is applied from the VSS or ground terminal of the device to the VDD terminal, and a current flows in the forward direction of the protection diode (61 to 63 in FIG. 6C) of the device. .

At time t2 when the time set in the timer 103 has elapsed, the second relay is turned on as shown in FIG. As a result, a measurement current is applied from the sense current source 111 to the device under measurement 120, and the forward voltage VF at the junction is detected by the voltage measurement unit 112. The detected value is sampled by the sampling unit 113, and the sampled voltage value Vf is sequentially stored in the measurement result storage area of the memory 102 (Step S).
6). As shown in FIG. 5, the first relay 107 is turned off at a time point t3 after the overlap time set in the delay circuit from the time point t2 when the sampling is started, and the power is supplied from the power supply current source 108 to the device 120. Is stopped (step S7).

Then, the stored sample values are displayed on a display or printed out, whereby the operator selects a forward voltage immediately after the power supply current source 108 is turned off. Since the level of the sampling value changes largely before and after the end point t3 of the power application, the selection can be easily performed. It should be noted that the forward voltage immediately after the power supply current source 108 is turned off may be automatically selected from the sampling value. That is, timer 1
Since the set value of “03” and the set value of the delay circuit 105 are known, the end point in time t3 is known, and there is a change in the level of the measured value. Choice is possible. For example, when the sampling resolution is set to 0.1 to 0.2 sec, the first sampling can be performed within 0.2 seconds after stopping the power application. The measured value of the forward voltage obtained by the first sampling after the power application is stopped is the measured value with the least error. This is because the junction temperature Tj of the chip rapidly decreases (for example, −5 ° C./sec) after the power supply is stopped, so that it is better to obtain a measured value as soon as possible.

Next, the stop signal from the timer 103 goes low, and the measuring current stops (step S8).
The CPU 10 determines the junction temperature Tj from the value Vf first sampled after stopping the power application current of the forward voltage of the sampled junction and the Tj or Vf table 1021.
1 (step S9).

As an example of the calculation, the forward voltage sampled immediately after stopping the application of 1 W power is V
Let f = 280 mV. Table 1 in which the Tj-Vf characteristic was measured in advance was used as the junction temperature Tj corresponding to Vf = 280 mV.
021 leads to Tj = 72 ° C. From the required package thermal resistance θ = (Tj−Ta) / Power, (72−
25) /1.0=47 [° C./W].

In the above description of the embodiment, the circuits 103 to 106 for controlling the switching timing between the power application and the forward voltage measurement, and the sampling measurement circuit 11
3. Apparatus 11 for measuring measurement diode forward voltage Vf
[0113] Although the example using the individual circuits is described in the example 0113, the function of the existing ASIC tester can be used.
That is, the ASIC tester has a function of programming a measurement procedure and a function of sampling measurement.
The main part of the function of the temperature measuring device can be realized by creating a program and executing the CPU 101.

According to this embodiment, the timer 103 can set the power application time, and the delay circuit 105 can set the overlap time between the power application and the measurement current application. Then, in the measurement of the forward voltage of the PN junction, the sampling of the forward voltage, which is the measured value, starts simultaneously with the start of the application of the measurement current. Thus, extremely rapid measurement within the sampling interval is realized, and an accurate forward voltage measurement result is obtained with the rapid measurement.

Next, an example in which the measuring method of the present invention is applied to an MCM or PWBA on which a plurality of chips are mounted will be described. In a module equipped with a plurality of devices, the power supply lines are generally connected in common, so that power can be individually applied to a plurality of devices,
It is not possible to measure the junction temperature by passing a measuring current. Therefore, in order to measure the junction temperature Tj of each device, only the VDD layer is separated as shown in FIG.
The chips are appropriately arranged as shown in FIG. As a result, power and current for measurement can be individually supplied even to a module on which a plurality of devices are mounted. The GND layer may be common as shown in FIG.

By employing a structure in which power is applied to each device separately, power can be separately applied to the diode 62 inside. Therefore, the influence of the junction temperature Tj due to the difference in the ratio of the calorific value of the device is determined by varying the power applied to each device.
It is possible to measure the junction temperature Tj of the device in consideration of the influence of other heating devices. Further, the influence of Tj due to the difference in the device arrangement position can be clarified as to where Tj is highest when the device is arranged by causing only the target device to generate heat and not applying power to the other devices. .

By separating the power supply VDD wiring as shown in FIG. 6, not only the power application becomes separate, but also when measuring the power consumption during actual operation in the actual machine, this VDD-G
By measuring the current between NDs, it becomes possible to classify which device has the largest power consumption. As an application example, a similar measuring device can be configured by monitoring the protection diode characteristics of one input terminal for each input pin.

[0025]

As described above, according to the method and apparatus of the present invention, the end portion of the power application period and the start portion of the application period of the measurement current are partially overlapped, and only the measurement current is applied. Since a switching time to the applied period is not required unlike the related art, a forward voltage can be obtained quickly, and highly accurate measurement can be performed. As described above, according to the present invention, a more accurate bonding temperature can be obtained, so that an accurate package thermal resistance can be obtained. As a result, in the past, an extra margin was added to the measurement result with a large error to take an excessive heat dissipation measure.However, the present invention has enabled high-precision measurement, so that an appropriate heat dissipation measure can be taken. Cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an apparatus according to an embodiment of the present invention;

FIG. 2 is a flowchart showing an example of a procedure of an embodiment of the measuring method of the present invention;

FIG. 3 is a diagram showing processing timing in the measurement method of the present invention;

FIG. 4 is a diagram showing a correlation characteristic of Vf-Tj.

FIG. 5 is a timing chart of a control signal,

6A is a diagram illustrating an example of a VDD pattern when three chips are mounted, FIG. 6B is a diagram illustrating an example of chip arrangement, and FIG. 6C is a diagram illustrating the concept of individual power supply for each chip;

FIG. 7 is a diagram illustrating an example of a monitoring result of a forward voltage Vf immediately after power application.

[Explanation of symbols]

100: semiconductor junction temperature measuring device, 101: CPU, 1
02 memory, 1021 Tj-Vf table, 103
... Timer, 104 ... Logic circuit, 105 ... Delay circuit, 10
6 ... Inverter, 107 ... First relay, 108 ... Power supply current source, 109 ... Second relay, 110 ... Forward voltage measurement unit, 111 ... Measurement current source, 112 ... Voltage measurement unit
113: sampling circuit, 120: semiconductor chip.

Claims (2)

[Claims] 1. A predetermined current is passed between power supply terminals of a semiconductor integrated circuit to be measured to bring a surface temperature of the semiconductor integrated circuit into a steady state, and after the surface temperature becomes a steady state, the predetermined current is cut off. Immediately before, a detection current sufficiently smaller than the predetermined current for measuring the junction temperature of the semiconductor integrated circuit is supplied to the power supply terminal, and the junction temperature is measured based on a voltage between the power supply terminals when the detection current is supplied. A method for measuring a joining temperature. 2. A power supply current source for supplying a prescribed power application current to a semiconductor integrated circuit to be measured, and a measurement current that is sufficiently smaller than the power supply current to the semiconductor semiconductor integrated circuit. A voltage measuring means for measuring a forward voltage of a PN junction; and after connecting the power applying current source to the semiconductor semiconductor integrated circuit for a predetermined period of time, when connecting the voltage measuring means, A control unit that controls the supply period of the measurement current and the supply period of the measurement current to partially overlap; a table that holds data indicating a correlation between a junction temperature and a forward voltage measured in advance for the semiconductor semiconductor integrated circuit; Calculating means for calculating the junction temperature by referring to the contents of the table from the measurement result of the voltage measuring means immediately after the supply of the power application current is stopped. Measuring device.