CN105004427A - Device and method for precisely testing temperature distribution of semiconductor device - Google Patents

Abstract

The invention discloses a device and a method for accurately testing the temperature distribution of a semiconductor device. The device of the invention includes a core control module, a large and small constant current source module, a high-speed current switching module, a constant temperature box, a high-speed data acquisition module, an infrared thermal imager, a host computer and a power supply module. The method of the invention includes providing an adjustable constant temperature environment and an accurate test current for the device under test, recording the ambient temperature and linear fitting of the corresponding forward voltage drop to obtain the K coefficient, heating the device under test to a stable state with the heating current, and then switching to the test current at a high speed , quickly sample the forward pressure drop and convert it with the K coefficient to obtain the cooling curve, process the cooling curve with fitting and smoothing methods to obtain a more accurate and complete cooling curve, and at the same time, the infrared thermal imager takes a temperature distribution map. Correct the temperature profile with the exact cooling curve temperature to obtain an accurate temperature profile. The invention uses an electrical test method to correct infrared thermal images, and has high accuracy in the temperature distribution test of semiconductor devices.

Description

Apparatus and method for accurately testing temperature distribution of semiconductor devices

technical field

The invention belongs to the technical field of transient thermal testing of semiconductor devices, in particular to a device and method for accurately testing the temperature distribution of semiconductor devices.

Background technique

Power semiconductor devices are high-heating electronic products, and the product life and normal operation are closely related to whether the product's operating junction temperature Tj exceeds the allowable maximum junction temperature Tjm. Tjm is an important rated value of the device, and it is a comprehensive technical and quality level indicator. Many other important technical indicators of the device are reflected and guaranteed by Tjm. Taking a high-power LED as an example, the increase of its working current will generate a lot of heat, which will cause a significant change in the pn junction temperature of the LED chip, which will have an important impact on the performance of the LED, resulting in changes in forward voltage drop, color temperature, and red wavelength. Shift, low photoelectric conversion efficiency, etc., affect its luminosity, chromaticity and electrical parameters. Therefore, quickly and accurately testing the junction temperature of power semiconductor devices is an important prerequisite for effective thermal management.

The infrared thermal imager uses the infrared detector and the optical imaging objective lens to receive the infrared radiation energy distribution pattern of the measured target and reflect it on the photosensitive element of the infrared detector to obtain an infrared thermal image, which is consistent with the thermal image on the surface of the object corresponding to the distribution field. In layman's terms, an infrared thermal imager converts the invisible infrared energy emitted by an object into a visible thermal image. Different colors on the thermal image represent different temperatures of the measured object. However, since the infrared thermal imager is a non-contact tester, the measurement is greatly affected by the intermediate medium and the test environment. Therefore, the temperature distribution accuracy of the infrared thermal image is low, and it cannot accurately reflect the temperature distribution of the shooting area. For example, the measurement accuracy of the German InfraTec (InfraTec) high-precision infrared thermal imaging camera VarioCAM®hr research (VCr for short) is only ±1°C. Therefore, using the contact temperature measurement method to correct the infrared thermal image can greatly improve the measurement accuracy of the infrared thermal image.

Contents of the invention

In view of the defects in the prior art, the object of the present invention is to provide a device and method for accurately testing the temperature distribution of semiconductor devices, which have high precision, small error and good stability.

To achieve the above object, the present invention adopts the following technical solutions:

A device for accurately testing the temperature distribution of semiconductor devices, including a host computer, a core control board, a high-speed current switching module, a large and small constant current source module, an infrared thermal imager, a constant temperature box, and a high-speed data acquisition module. The core control board is connected to the serial port, the core control board is connected to the high-speed current switching module, the large and small constant current source module and the constant temperature box in turn, the infrared thermal imager is connected to the host computer, the high-speed current switching module, the large and small constant current source module, The infrared thermal imaging cameras are respectively connected to the devices under test in the incubator, and the devices under test are connected to the host computer through a high-speed data acquisition module.

The thermostat is a dry thermostat with a control accuracy of ≥0.5°C.

The current ripple coefficient of the large and small constant current source modules is ≤1%.

A method for accurately testing the temperature distribution of a semiconductor device, using the above-mentioned device, comprising the steps of:

a. Place the device to be tested in an incubator, and evenly apply a heat-conducting material between the device to be tested and the incubator;

b. Input the test current value in the host computer and send it to the core control board to drive the large and small constant current source modules to provide test current for the device under test;

c. Input the initial temperature value and step temperature value in the host computer, and send it to the core control board to drive the incubator to provide different ambient temperatures for the device under test. The high-speed data acquisition module collects the voltage value at the corresponding temperature and uploads it to the host computer ;

d. The host computer linearly fits the voltage values at different ambient temperatures and corresponding temperatures to obtain the K coefficient;

e. Input the heating current value, test current value, heating time and test time in the host computer, and send it to the core control board to drive the large and small constant current source module to provide heating current for the device under test. After the heating time is over, the high-speed current switching module Quickly switch the heating current to the test current, the high-speed acquisition module collects the voltage value under the test current, and the infrared thermal imager records the corresponding temperature distribution changes;

f. The high-speed acquisition module transmits the voltage change to the host computer, and the host computer divides the voltage change by the K coefficient to obtain the cooling curve;

g. Use the fitting method in the host computer to fit the data in the short period of time before the cooling curve, integrate the fitted data with the data in the latter part and then perform smoothing to obtain a more accurate and complete cooling that reflects the temperature of the device under test curve;

h. The upper computer corrects the temperature of the precise cooling curve and the temperature distribution map recorded by the infrared thermal imager to obtain an accurate temperature distribution map.

In the step c, the sampling rate of the high-speed data acquisition module is ≥1M/s.

The switching time of the high-speed current switching module in step e is ≤1 μs.

The fitting method in the step g includes a square root fitting method and an exponential fitting method, and the smoothing method includes Fourier series expansion smoothing and regularization smoothing; wherein the exponential fitting method is both for noisy cooling curve signals There is a fitting effect and a smoothing effect, so the exponential fitting method combines fitting and smoothing into one step, while the other fitting methods and smoothing methods are two steps; the fitting and smoothing of the measured cooling curve can effectively improve the test Random errors in the data.

Compared with the prior art, the present invention has the following obvious outstanding substantive features and significant progress:

The present invention provides corresponding test settings and test environment for the device to be tested by designing an embedded control system, and can obtain an accurate value of the temperature of the device, and use the accurate value to correct the infrared thermal image, thereby obtaining the precise temperature of the accurate infrared thermal image distributed. The invention has the characteristics of high precision, small error and good stability, and the precise temperature distribution test of semiconductor devices can be carried out through the device and method of the invention.

Description of drawings

FIG. 1 is a flow chart of the method for accurately testing the temperature distribution of a semiconductor device according to the present invention.

FIG. 2 is a schematic structural view of the device for accurately testing the temperature distribution of semiconductor devices according to the present invention.

Detailed ways

Below in conjunction with accompanying drawing, preferred embodiment of the present invention is described in detail as follows:

As shown in Figure 2, a device for accurately testing the temperature distribution of semiconductor devices includes a host computer 1, a core control board 2, a high-speed current switching module 3, a large and small constant current source module 4, an infrared thermal imager 5, and a constant temperature box 6. High-speed data acquisition module 7, the host computer 1 is connected to the serial port of the core control board 2, and the core control board 2 is connected to the high-speed current switching module 3, the large and small constant current source module 4 and the thermostat 6 in turn, and the infrared thermal The imager 5 is connected to the host computer 1, the high-speed current switching module 3, the large and small constant current source module 4, and the infrared thermal imager 5 are respectively connected to the device under test in the thermostat 6, and the device under test passes through the high-speed data acquisition module 7 Connect to host computer 1.

The thermostat 6 is a dry thermostat with a control accuracy of ≥0.5°C.

The current ripple coefficient of the large and small constant current source modules 4 is ≤1%.

As shown in Figure 1, a method for accurately testing the temperature distribution of a semiconductor device, using the above-mentioned device, includes the following steps:

a. Place the device to be tested in the incubator 6, and evenly apply a heat-conducting material between the device to be tested and the incubator 6;

b. Input the test current value in the host computer 1, and send it to the core control board 2 to drive the large and small constant current source module 4, and provide the test current for the device under test;

c. Input the initial temperature value and step temperature value in the host computer 1, and send them to the core control board 2 to drive the thermostat box 6 to provide different ambient temperatures for the device under test. The high-speed data acquisition module 7 collects the voltage value at the corresponding temperature and Upload to host computer 1;

d. The upper computer 1 linearly fits the voltage values at different ambient temperatures and corresponding temperatures to obtain the K coefficient;

e. Input the heating current value, test current value, heating time and test time in the host computer 1, and send them to the core control board 2 to drive the large and small constant current source module 4 to provide heating current for the device under test. After the heating time is over, the high-speed The current switching module 3 quickly switches the heating current to the test current, the high-speed acquisition module 7 collects the voltage value under the test current, and the infrared thermal imager 5 records the corresponding temperature distribution changes;

f. The high-speed acquisition module 7 transmits the voltage change to the host computer 1, and the host computer 1 divides the voltage change by the K coefficient to obtain the cooling curve;

g. Use the fitting method in the upper computer 1 to fit the data in the short period of time before the cooling curve, integrate the fitted data with the data in the latter part and then perform smoothing to obtain a more accurate and complete reflection of the temperature of the device under test cooling curve;

h. The upper computer 1 corrects the temperature of the precise cooling curve and the temperature distribution map recorded by the infrared thermal imager 5 to obtain an accurate temperature distribution map.

In the step c, the sampling rate of the high-speed data acquisition module 7 is ≥1M/s.

The switching time of the high-speed current switching module 3 in the step e is ≤1 μs.

The fitting method in the step g includes a square root fitting method and an exponential fitting method, and the smoothing method includes Fourier series expansion smoothing and regularization smoothing; wherein the exponential fitting method is both for noisy cooling curve signals There is a fitting effect and a smoothing effect, so the exponential fitting method combines fitting and smoothing into one step, while the other fitting methods and smoothing methods are two steps; the fitting and smoothing of the measured cooling curve can effectively improve the test Random errors in the data.

Principle of the present invention is as follows:

In the testing process of the device of this embodiment, the excellent linear relationship between the pn junction forward voltage drop and the junction temperature of the semiconductor device is used to provide an adjustable constant temperature environment and an accurate test current for the device under test. The test current is to make the device under test positive Guide the current that is conducting but not self-heating, record the ambient temperature and the corresponding forward voltage drop linear fitting to get the K coefficient under the test current; then heat the device under test to a stable state under the heating current, and switch to For the test current, due to the diffusion of heat, the forward voltage drop of the device under test presents a transient rising process. This process is quickly sampled and converted with the K coefficient to obtain the cooling curve of the device under test, which accurately reflects the The temperature of the device is measured, and the infrared thermal imager captures the temperature distribution map of this process. The accurate temperature distribution map can be obtained by correcting the temperature distribution map of the infrared thermal imager with the accurate temperature obtained by the electrical test method.

Claims (7)

1. the device for accurate semiconductor test Temperature Distribution, it is characterized in that, comprise host computer (1), core control panel (2), high speed electric current handover module (3), size constant current source module (4), thermal infrared imager (5), constant temperature oven (6), high-Speed Data-Acquisition Module (7), described host computer (1) is connected with core control panel (2) serial ports, described core control panel (2) connects high speed electric current handover module (3) successively, size constant current source module (4) and constant temperature oven (6), described thermal infrared imager (5) connects host computer (1), described high speed electric current handover module (3), size constant current source module (4), thermal infrared imager (5) connects the device under test in constant temperature oven (6) respectively, described device under test connects host computer (1) by high-Speed Data-Acquisition Module (7).

2. the device for accurate semiconductor test Temperature Distribution according to claim 1, is characterized in that: described constant temperature oven (6) is dry type constant temperature oven, control accuracy >=0.5 DEG C.

3. the device for accurate semiconductor test Temperature Distribution according to claim 1, is characterized in that: current ripples coefficient≤1% of described size constant current source module (4).

4., for a method for accurate semiconductor test Temperature Distribution, apply device as claimed in claim 1, it is characterized in that, comprise the steps:

A. device under test is positioned in constant temperature oven (6), and between device under test and constant temperature oven (6) uniform application Heat Conduction Material;

B. input test current value in host computer (1), sends core control panel (2) to and drives size constant current source module (4), for device under test provides measuring current;

C. input initial temperature value and stepping temperature value in host computer (1), sending core control panel (2) to drives constant temperature oven (6) to provide varying environment temperature for device under test, and the magnitude of voltage that high-Speed Data-Acquisition Module (7) gathers under corresponding temperature is also uploaded to host computer (1);

D. the magnitude of voltage under varying environment temperature and corresponding temperature is carried out linear fit and obtains k-factor by host computer (1);

E. input heating current value, measuring current value, heat time and the test duration in host computer (1), sending core control panel (2) to drives size constant current source module (4) to provide heating current for device under test, after time to be heated terminates, heating current is switched to measuring current rapidly by high speed electric current handover module (3), magnitude of voltage under high speed acquisition module (7) collecting test electric current, simultaneously thermal infrared imager (5) record corresponding temperature changes in distribution;

F. change in voltage is sent to host computer (1) by high speed acquisition module (7), and voltage variety and k-factor are divided by and obtain cooling curve by host computer (1);

G. adopt in the host computer (1) approximating method to the data fitting in this cooling curve leading portion short time, by the smoothing cooling curve obtaining more accurate and complete reflection device under test temperature again after the data after matching and back segment Data Integration;

H. the temperature profile that the temperature of accurate cooling curve and thermal infrared imager (5) record corrects and obtains accurate temperature profile by host computer (1).

5. the method for accurate semiconductor test Temperature Distribution according to claim 4, is characterized in that: described step c high speed data acquisition module (7) sampling rate >=1M/s.

6. the method for accurate semiconductor test Temperature Distribution according to claim 4, is characterized in that: described step e high speed current switching module (3) switching time≤1 μ s.

7. the method for accurate semiconductor test Temperature Distribution according to claim 4, it is characterized in that: the approximating method in described step g comprises square root approximating method and exponentially fitted method, described smoothing method comprises that Fourier expansion is level and smooth and regularization is level and smooth; Wherein exponentially fitted method is intended to cooperate with also having smoothing effect for noisy cooling curve signal is existing, and therefore exponentially fitted method is by matching and smoothly merges into a step, and all the other approximating methods and smoothing method are two steps; To actual measurement cooling curve matching and the random error that smoothly effectively can improve test data.