JPH0423446A - Evaluating method of reliability of semiconductor element - Google Patents

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.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Field of Application) The present invention relates to a method for testing semiconductor devices, and particularly to reliability evaluation in a 100% inspection process of diodes before product shipment.

(Prior art) A method for inspecting a diode inside a semiconductor device is shown in Figures 1 and 2.
This will be explained with reference to the figures. That is, as shown in FIG.
A interrupting current measuring device 2 is disposed near the transport path 1, and a part of the conveyance path 1 is provided with a room temperature measuring section 3 and a high temperature measuring section 4 that can maintain a high temperature by installing a heater. A heat insulating material 5 is installed near the boundary between the high temperature measurement section 4 and the conveyance path 1 to prevent high temperature from affecting other components. A device with such a structure will be called a high-temperature handler (HandQer).
It is written as. In the actual measurement, the interrupting currents IRI and IR2 at room temperature and high temperature will be measured, but in advance, as many semiconductor devices to be measured as possible, such as diodes, are measured to obtain the correlation diagram shown in Figure 2 between the two. Perform multiple tests on diode reliability. This test consists of an energization test in which a predetermined current and voltage is applied to n semiconductor devices to be measured, and the limit of deterioration by leaving each device in hot and humid conditions for one week. The non-defective region A shown in FIG. 2 is determined by taking into account the values that are likely to cause initial defects based on many years of experience. In FIG. 2, 6 and 7 correspond to areas where the product is likely to become early failure in the market, and 8 is the area where early failure occurs. Although not shown in this figure, the so-called log
) scale (ScaQe).

By the way, the high-temperature handler equipped with the breaking current measuring device 2 is equipped with a so-called microcomputer with arithmetic functions, which stores in advance the non-defective area A shown in FIG. The room-temperature cut-off current IR of a semiconductor element to be measured, such as a varicap diode, which is carried to measurement position B, is measured. Next, heat it in advance at position C and hold it at approximately 80℃ at measurement position D.
Measure R2.

Note that Ll, L2, and L3 shown in FIG. 2 indicate boundaries between good products and defective products in terms of breaking current.

(Problems to be Solved by the Invention) Such high-temperature handlers require measurement mechanisms at room temperature and high temperature, which naturally increases equipment costs.In addition, since the semiconductor device to be measured is heated by an indirect heating mechanism, It takes time to reach the temperature, ff1l + constant index (
Index) inevitably becomes slow, which is not preferable for improving productivity. Furthermore, maintenance of high temperature handlers is more difficult than that of room temperature handlers. The present invention was developed under these circumstances, and particularly aims to remove semiconductor elements to be measured that are likely to become initially defective in the final step of the manufacturing process.

[Structure of the Invention] (Means for Solving the Problem) The reliability of the semiconductor device according to the present invention is that a semiconductor device under test whose change ratio of cut-off current measured at room temperature and high temperature is within a set range is considered to be a good product. There are characteristics of gender evaluation methods.

(Function) In the present invention, a method is adopted in which the high temperature required for a high-temperature handler, for example, 80°C, is heated from inside the semiconductor device under test by power loss of voltage and current. The present invention was completed based on the knowledge that a stable and highly reliable product characteristic range can be found. This makes it possible to remove semiconductor devices to be measured that are likely to be initially defective in the final inspection step of the manufacturing process.

(Example) An example according to the present invention will be described with reference to FIGS. 3 and 4. The cross-sectional view in FIG. 3 shows the main parts of a high temperature handler equipped with a microcomputer with arithmetic functions, and stores the measurement results of the interrupting current IRI at room temperature. A semiconductor element to be measured, such as a varicap diode 10, is carried by a conveyance path 11 to the position of a breaking current measuring device 12, and terminals 13.1 for normal temperature or high temperature measurement are connected to both poles of the varicap diode 10.
Connect 4. When measuring high temperature with the interrupting current measuring device 12, voltage and current are applied so that the junction temperature of the varicap diode 10 to be measured reaches the specified operating temperature.
This voltage is determined by the breakdown voltage, and since it varies from element to element, the power is maintained constant by adjustment using the energizing current.

By the way, in the breaking current measurement performed by the breaking current measuring device 12 shown in FIG. 3, the breaking current at normal temperature and the breaking current at high temperature, for example 80°C, are measured as in the conventional example, and the progress of temperature rise due to voltage application is also measured. It is shown in Figure 4. As shown in Figure 4, which shows the measurement time chart, when the temperature reaches the saturated state, the supply of voltage and current is stopped, and the high temperature measurement terminal 14 shown in Figure 3 is immediately connected. Switch.

For the actual measurement, first electrically connect the measurement terminal 13 to the varicap diode 10 to be measured, as shown in the time chart, and measure the interrupting current IRI at room temperature.
), after 200 milliseconds (Second) elapsed (
(See Figure 4 2) Move to high temperature cutoff current measurement. After switching to the high temperature measurement terminal 14, the temperature from normal temperature to 8
After adjusting the junction temperature of the varicap diode 10 to be measured to about 0°C, measure the interrupting current IR2 (see Fig. 4, 3).
IR1/IR2 is calculated by a microcomputer attached to the high-temperature handler, and it is determined whether the measurement result is within the non-defective region A of the correlation diagram shown in FIG. 2 to determine whether the product is good or defective. It should be noted that, as stated in the prior art section, the non-defective area A has been established based on current tests, tests in high-temperature, high-humidity atmospheres, and many years of experience. As shown in Figure 4, the high temperature cut-off current IR2 is measured after the heating voltage and current sources are turned off, so the voltage and current are applied and energized in anticipation of the temperature drop that will occur (see Figure 4). Set the value and heat.

[Effects of the Invention] As described above, the method for evaluating the reliability of semiconductor devices according to the present invention enables the measurement of the cut-off current of, for example, a varicap diode using a handler at room temperature, and also predicts and selects initial failures. Trouble (TroubQ)
e) can be solved, which brings about a great effect in terms of mass production.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing the main parts of a conventional breaking current measuring device, Fig. 2 is a correlation diagram created from the measurement results at room temperature and high temperature, and Fig. 3 is a main part of the breaking current measuring device used in the method of the present invention. FIG. 4 is a time chart of breaking current measurement. 1.11: Conveyance path, 2.12: Breaking current 41 window device, 3: Room temperature measurement section, 4: High temperature measurement section, 5: Insulation material, 6.7: Area prone to initial failure, 7: Initial failure Area, A: Good product area, 10: Varicap diode, 13: Terminal for normal temperature measurement, 14: Terminal for high temperature measurement.

Claims (1)

[Claims] A reliability evaluation method for a semiconductor device, characterized in that a semiconductor device under test whose change ratio of cut-off current measured at room temperature and high temperature is within a set range is considered to be a good product.