JP2000124273A - Semiconductor integrated circuit and method for inspecting its electric characteristics - Google Patents

Abstract

PROBLEM TO BE SOLVED: To assure a precision inspection for electric characteristics even with high contact resistance of an LSI tester resource, by separately controlling on/off of a plurality of output circuits when inspecting an electric characteristics from a current outputted from an electrode. SOLUTION: A semiconductor integrated circuit 35 is provided with an output part 20 which comprises four output circuits 21-24, a selection circuit 36, and an electrode 11. The four output circuits 21-24 are connected in parallel by their common data input 25 and common data output 30. At inspection for electric characteristics, the output circuits 21-24 are sequentially turned on one by one, and electric characteristics are inspected for each of the output circuits 21-24 which is turned on. Thus, even if a contact resistance of an LSI tester power-source which contacts to the electrode 11 of the semiconductor integrated circuit to be tested is high, a high precision in inspection for electric characteristics is assured, eliminating a misjudgment where a sound article is taken as defective one.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a semiconductor integrated circuit and a method for inspecting electrical characteristics thereof.

[0002]

2. Description of the Related Art After completion of a diffusion step, electrical characteristics of a semiconductor integrated circuit formed on a semiconductor wafer are inspected in a wafer state to determine a non-defective / defective product. On this occasion,
The contact resistance between the electrode surface of the semiconductor integrated circuit and the needle of the probe card fluctuates due to the warpage of the semiconductor wafer or the probe card, the degree of equilibrium with the wafer stage, or the displacement of the needle of the probe card. In particular, with the recent miniaturization of the process, the fluctuation of the contact resistance has been increasing.

[0003] Among the electrical characteristic tests, the output current test measures the current capability of an output circuit. FIG. 2 shows an electrical equivalent circuit at the time of output current measurement by voltage application current measurement in a conventional example. In FIG. 2, 1 is an LSI tester resource, 2 is a semiconductor integrated circuit to be tested, and 3 is a contact resistance generated when the LSI tester resource 1 and the semiconductor integrated circuit 2 are connected. Reference numeral 4 denotes an equivalent circuit of an output circuit provided in the semiconductor integrated circuit 2. The output circuit 4 includes a transistor equivalently represented by an on-resistance 6 and a switch 7 supplied with a voltage from a power supply 5, and a ground 8 A transistor is equivalently represented by an on-resistance 9 supplied with a voltage and a switch 10. Reference numeral 11 denotes an electrode for connecting the output of the output circuit 4 to the outside.

In the output current test, when the output current on the low side is measured, in the output circuit 4, the switch 7 is turned off and the switch 10 is turned on, and the electrode 11 of the semiconductor integrated circuit 2 is turned on.
The LSI tester resource 1 applies the voltage VOL to the power supply, and the current flowing at that time is measured. Based on whether or not the current value IOL falls within the criterion, a good / defective product is determined. Similarly, when measuring the output current on the high side, the output circuit 4
The switch 7 is on, the switch 10 is off, and the LSI tester resource 1 is applied to the electrode 11 of the semiconductor integrated circuit 2 by the voltage VOH.
Is applied, and a good / defective product is determined based on whether or not the current value IOH flowing at that time falls within the determination standard.

FIG. 3 shows a state in which the needle of the probe card is applied. In FIG. 3, reference numeral 12 denotes a semiconductor wafer on which a plurality of semiconductor integrated circuits (chips) 2 are formed in a grid pattern;
Reference numeral 3 denotes a wafer stage that holds the semiconductor wafer 12 by suction. Reference numeral 14 denotes a probe card provided above the wafer stage 13, and reference numeral 15 denotes a probe needle for bringing the probe card 14 into contact with the electrode 11 of the semiconductor integrated circuit 2. The probe card 14 includes the semiconductor integrated circuit 2
The probe needle 15 is provided for each of the plurality of electrodes 11.

[0006]

However, in the above conventional example, when the electrodes of the semiconductor integrated circuit are electrically connected to the LSI tester resources, the contact resistance 3 is added in series to the on-resistance of the output circuit. If this contact resistance increases,
The measurement accuracy of the output current test is reduced, and a non-defective product is determined as a defective product. This erroneous determination will be described in detail below.

Now, it is assumed that the resistance of the measuring system in the LSI tester resource 1 is negligible and the electrode 1 of the semiconductor integrated circuit 2 is
It is assumed that the contact resistance 3 between 1 and the probe needle 15 varies from 0.1 [Ω] to 10 [Ω]. This contact resistance 3 is
The warp of the semiconductor wafer 12 or the probe card 14 shown in FIG.
It fluctuates due to the change of the needle point of No. 5. Also, voltage VOL = 0.4
In a semiconductor integrated circuit provided with an output circuit having characteristics such as an output current IOL = 50 [mA] at [V], a low-side determination criterion of the output circuit of the semiconductor integrated circuit is used in measuring the low-side output current. , Voltage VOL = 0.4 [V] and current IOL = 25 [mA]. That is, assuming that the resistance of the additional circuit such as the protection resistor of the output circuit 4 can be neglected, the ON resistance 9 of the low-side transistor of the output circuit 4 is 8 [Ω].

FIG. 4 shows a change in the output current IOL when the contact resistance 3 changes from 0.1 [Ω] to 10 [Ω]. When the on-resistance 9 of the output circuit is 8 [Ω], the contact resistance 3 is 8 [Ω].
Above [Ω], the value is lower than IOL = 25 [mA], which is the judgment reference current. In this case, a good product is erroneously determined as a defective product.

The above-described erroneous determination is remarkably generated in an output circuit having a large current driving capability, that is, an output circuit having a small on-resistance. The increase in the contact resistance 3 of the LSI tester resources also affects a contact test for confirming the electrical connection between the electrodes and the internal circuit or between the internal circuit and the LSI tester resources.

As described above, when the contact resistance 3 largely fluctuates, the inspection accuracy of the electrical characteristics is reduced, and a good product is erroneously determined as a defective product.

[0011] It is an object of the present invention to inspect an electrical characteristic of a semiconductor integrated circuit even when the contact resistance of an LSI tester resource in contact with an electrode of the integrated circuit under test is high. It is an object of the present invention to ensure high accuracy and accurately determine a good / defective product.

[0012]

In order to solve the above problems, according to the present invention, the on-resistance of the output circuit relative to the contact resistance of the LSI tester resource is compared with that at the time of normal operation during the inspection of electrical characteristics. In this case, a configuration in which the height is increased is adopted.

That is, the semiconductor integrated circuit according to the first aspect of the present invention includes a plurality of output circuits for outputting current to the electrodes, and the plurality of output circuits have inputs and outputs connected in common. When inspecting an electrical characteristic based on a current value output from the electrode, a selection unit that individually controls on / off of the plurality of output circuits is provided.

According to a second aspect of the present invention, in the semiconductor integrated circuit according to the first aspect, the plurality of output circuits are controlled to be on and off in the same state during normal operation. I do.

Further, according to a third aspect of the present invention, in the semiconductor integrated circuit according to the first or second aspect, when the electrical characteristics are inspected, the selecting means sequentially connects the plurality of output circuits one by one. It is characterized in that it has a built-in register that specifies to turn on individually.

According to a fourth aspect of the present invention, in the semiconductor integrated circuit according to the first or second aspect, information for individually controlling on / off of the plurality of output circuits when inspecting electrical characteristics. Is input to the selection means from outside the semiconductor integrated circuit.

According to a fifth aspect of the present invention, in the semiconductor integrated circuit according to the first or second aspect, the plurality of output circuits are formed of transistors having the same characteristics.

Further, according to a sixth aspect of the present invention, there is provided a method for inspecting electrical characteristics of a semiconductor integrated circuit, comprising a plurality of output circuits for outputting a current to an electrode, wherein the plurality of output circuits have a common input and a common output. A method for inspecting electrical characteristics of a semiconductor integrated circuit connected to the device, wherein when inspecting electrical characteristics by a current value output from the electrodes, the plurality of output circuits are sequentially turned on individually one by one. The electrical characteristic is inspected for each output circuit that has been turned on.

According to a seventh aspect of the present invention, in the method for inspecting electrical characteristics of a semiconductor integrated circuit according to the sixth aspect, when inspecting electrical characteristics, a probe needle of a probe device contacts the electrode. It is characterized by doing.

With the above configuration, according to the present invention, at the time of inspection of the electrical characteristics, a plurality of (for example, N) output circuits connected in parallel sequentially turn on one by one, and the electric circuit is turned on for each of the output circuits that have turned on. The properties are checked. As a result, the on-resistance of the operated output circuit becomes N times as large as that in the normal operation in which all of these output circuits are operated, for example, when all the output circuits are formed of transistors having the same characteristics. Become. Therefore, even if the contact resistance of the LSI tester resource that contacts the electrode of the semiconductor integrated circuit under test is high, this contact resistance is relatively small with respect to the N-times ON resistance of the output circuit. Therefore, the influence of the contact resistance can be reduced or ignored, the inspection accuracy of the electrical characteristics can be secured high, and a good product is not erroneously determined as a defective product.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of a semiconductor integrated circuit of the present invention and a method for inspecting electrical characteristics thereof will be described.

FIG. 1 shows a semiconductor integrated circuit according to the present embodiment. In the figure, reference numeral 35 denotes a semiconductor integrated circuit having an output unit 20. The output unit 20 includes four output circuits 21
24, the selection circuit 36, and the electrode 11. The four output circuits 21 to 24 have their common data input 2
5 and a common data output 30 connected in parallel. The output circuit 21 has a NAND circuit 31 having a control input 26 and a common data input 25 as inputs, an inverter 32 having a control input 26 as an input, and an input having a common data input 25 as an output of the inverter 32. NOR circuit 33
And a CMOS transistor 34 which receives the outputs of the NAND circuit 31 and the NOR circuit 33 as inputs and outputs a common data output 30. Output circuit 22, 2
Numerals 3 and 24 each have control inputs 27, 28 and 29 and a common data input 25 as inputs and a common data output 30 as outputs, and have the same internal configuration as the output circuit 21. . The four output circuits 21 to 24 are formed of transistors having the same characteristics among each other, and have the same on-resistance between the output circuits.

The common data output 30 is connected to the electrode 11, to which the LSI tester resource 1 is connected when the electrical characteristics of the semiconductor integrated circuit 35 are inspected. The contact resistance at this time is indicated by reference numeral “3”.

The selection circuit (selection means) 36
Control signals are output to control inputs 26 to 29 to the output circuits 21 to 24, respectively. These control signals are output to the output circuits 21 to 24 when the electrical characteristics of the semiconductor integrated circuit 35 are inspected.
Is a signal for individually controlling on and off.

As described above, when the four output circuits 21 to 24 are connected in parallel and the CMOS transistors 34 of the output circuits 21 to 24 can be individually turned on and off, the output circuit 21 The on-resistance of each of the low-side transistors 24 to 24 is 3 when the low-side determination criterion of the output unit 20 is, for example, voltage VOL = 0.4 [V] and current IOL = 25 [mA].
2 [Ω]. In this case, since the on-resistance is larger than the contact resistance 3, the influence of the contact resistance 3 is reduced.
As shown in the above, even if the contact resistance 3 varies from 0.1 [Ω] to 10 [Ω], the current IOL does not fall below the criterion (IOL = 6.25 [mA]) of each of the output circuits 21 to 24. In addition, even if the contact resistance 3 increases beyond this range, a non-defective product is not determined as a defective product.

The output unit 20 shown in FIG. 1 is represented by an electrical equivalent circuit, which is denoted by reference numeral "40" in FIG. Output circuit 21,
22, 23, and 24 are respectively 41, 42, 43, and
44 corresponding. Reference numerals 51 to 58 denote on-resistances of the respective transistors, and reference numerals 61 to 68 denote switches indicating on / off of the respective transistors.

The inspection of the electrical characteristics of the semiconductor integrated circuit 35 shown in FIG. 1, particularly the measurement of the output current, is performed according to the procedure shown in FIG. This procedure is stored in a register (not shown) built in the selection circuit 36 in advance. However, control input 2
The control signals 6, 27, 28, and 29 need not necessarily be incorporated in the register, and the control signals may be externally input to the external terminals of the semiconductor integrated circuit 35 and provided to the selection circuit 36. .

First, as shown in step 100 of FIG.
When the output current on the ow side is measured, Low is applied to the common data input 25, and Low is applied to the control inputs 26, 27, 28, and 29, respectively. This is a state where all the switches 61 to 68 in FIG. 6 are turned off.

Then, as shown in step 101 of FIG. 7, the output current of the output circuit 21 is measured. The selection of the output circuit 21 is performed by the control input 26. The control input 26 is set to High, and the control inputs 27, 28 and 29 are set to Lo
When w is set, the low-side transistor of the output circuit 21 is turned on, and the LSI tester resource 1 measures the low-side output current of the output circuit 21. This corresponds to a state where only the switch 61 in FIG. 6 is turned on.

In the subsequent sequence, as shown in step 102, the output current on the low side of the output circuit 22 is measured similarly to the output circuit 21. Control inputs 26, 28, 29
If the control input 27 is set to Low and the control input 27 is set to High, the LSI tester resource 1 measures the low-side output current of the output circuit 22. This is equivalent in circuit to the state where only the switch 62 in FIG. 6 is turned on.

In the subsequent sequence, as shown in step 103, the control inputs 26, 27 and 29 are set to low,
When 8 is set to High, the LSI tester resources 1
The output current on the ow side will be measured. This is equivalent in circuit to the state where only the switch 63 in FIG. 6 is turned on.

Finally, as shown in step 104 of FIG. 8, the control inputs 26, 27, and 28 are set to Low, and the control input 29 is set to H.
If igh is set, the LSI tester resource measures the low-side output current of the output circuit 24. This is equivalent in circuit to the state where only the switch 64 in FIG. 6 is turned on.

Assuming that the number of output circuits composed of transistors connected in parallel and having the same characteristics is N, output current measurement is performed N times in accordance with the number of output circuits. In addition, at the time of low output during actual operation, the common data input 25 becomes low, and the four terminals of the control inputs 26 to 29 simultaneously become high.
This is a state where all the switches 61 to 64 in FIG. 6 are turned on.

For example, by connecting the output circuits in parallel, an output circuit capable of varying the output current such as a current IOL = 4, 8, 12, or 24 [mA] is realized. When the connection is controlled and switched, the output current of each output circuit is measured, and if this measurement is replaced with the measurement of each output current capability, the measurement can be performed without increasing the inspection time. is there.

The measurement of the output current on the low side has been described as an electrical characteristic. However, the measurement of the output current on the high side can be performed in the above-described steps by setting the data input 25 to high in step 100. It is. Also, the voltage applied current measurement was described as a method of measuring the output current,
The same applies to current applied voltage measurement. Further, the output circuits connected in parallel are constituted by transistors having the same characteristic (same ON resistance), but may be a combination of output circuits 21 to 24 having different characteristics. In addition, the measurement of the output current may be performed in a wafer state or a package state.

[0036]

As described above, according to the semiconductor integrated circuit and the method for inspecting electrical characteristics of the semiconductor integrated circuit according to the present invention, a plurality of output circuits that operate in the same state during normal operation are provided, and these output circuits are connected in parallel. When the electrical characteristics of the semiconductor integrated circuit to be inspected are inspected, the operation of ON-controlling only one of the plurality of output circuits is individually repeated for each output circuit. By increasing the on-resistance of the circuit compared to the normal operation, the contact resistance between the semiconductor integrated circuit to be inspected and the resources of the LSI tester can be relatively reduced or ignored, thereby improving the inspection accuracy of the electrical characteristics. This makes it possible to accurately determine a good / defective product.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a semiconductor integrated circuit according to an embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit at the time of measuring output current in the related art.

FIG. 3 is a diagram showing a state in which a probe needle is applied to a tip.

FIG. 4 is a diagram showing a state of judgment at the time of a conventional output current test.

FIG. 5 is a diagram showing a determination situation at the time of an output current test according to the embodiment of the present invention.

FIG. 6 is a diagram showing an equivalent circuit at the time of output current measurement in the embodiment of the present invention.

FIG. 7 is a diagram showing a method for measuring an output current according to the embodiment of the present invention.

[Description of Signs] 1 LSI tester 3 Contact resistance 11 Electrode 12 Semiconductor wafer 14 Probe card 15 Probe needle 20, 40 Output unit 21 to 24, 41 to 44 Output circuit 25 Common data input 26 to 29 Control input 30 Common data Output 31 NAND circuit 32 Inverter 33 NOR circuit 34 CMOS transistor 35 Semiconductor integrated circuit 36 Selection circuit (selection means) 51-58 Transistor on-resistance 61-68 Switch 100 Low output setting step 101-104 Low-side output current of output circuit Measurement steps

Continued on front page F term (reference) 2G032 AB01 AC03 AD01 AE07 AE08 AF02 AG01 AK11 AK15 AL03 4M106 AA01 AA02 AA08 AC07 AC08 BA01 BA14 CA70 DD30 5F038 AV06 BE05 CD08 DF14 DT02 DT05 DT10 DT18 EZ20

Claims (7)

[Claims] An output circuit for outputting a current to an electrode is provided. The plurality of output circuits are configured such that inputs and outputs are connected in common, and an electrical characteristic is determined by a current value output from the electrode. A semiconductor integrated circuit, comprising: selecting means for individually controlling on / off of the plurality of output circuits when inspecting the semiconductor integrated circuit. 2. The semiconductor integrated circuit according to claim 1, wherein the plurality of output circuits are turned on and off in the same state during normal operation. 3. The circuit according to claim 1, wherein the selection means includes a register for designating the plurality of output circuits to be individually turned on one by one when the electrical characteristics are inspected. 3. The semiconductor integrated circuit according to item 2. 4. The semiconductor device according to claim 1, wherein when the electrical characteristics are inspected, information for individually controlling on / off of the plurality of output circuits is input to the selection unit from outside the semiconductor integrated circuit. Or the semiconductor integrated circuit according to 2. 5. The semiconductor integrated circuit according to claim 1, wherein said plurality of output circuits are composed of transistors having the same characteristics. 6. A method for inspecting electrical characteristics of a semiconductor integrated circuit, wherein a plurality of output circuits for outputting a current to an electrode are provided, wherein the plurality of output circuits are configured such that inputs and outputs are commonly connected. When inspecting the electrical characteristics based on the current value output from the electrode, the plurality of output circuits are sequentially turned on individually one by one, and the electrical characteristics are inspected for each output circuit that has been turned on. A method for inspecting electrical characteristics of a semiconductor integrated circuit. 7. The method according to claim 6, wherein a probe needle of a probe device comes into contact with the electrode when inspecting the electrical characteristics.