JP2919312B2 - Inspection method for semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a method of inspecting a semiconductor equipment, in particular the bias voltage of a predetermined region of the semiconductor device,
For example measuring Allowed the bias voltage of the semiconductor substrate from the external terminal
The present invention relates to an inspection method of a semiconductor device to be enabled .

[0002]

2. Description of the Related Art Measuring a step-down circuit in a semiconductor substrate, a substrate potential, and the like is performed by a dynamic random access memory (DRAM).
This is important in evaluating the characteristics of the access memory.

FIG. 7 shows a conventional simple circuit example for detecting an internal potential such as a substrate potential of a semiconductor substrate from the outside.
Referring to FIG. 2, the internal power supply generation circuit 33 of the semiconductor substrate covered with the package is connected to the external terminal 3 outside the package.
1, and the voltage of the external terminal 31 is measured by a tester or the like. In this case, the number of terminals 31 dedicated to measurement increases in accordance with the number of circuits 33 to be measured.

If the standard number of external terminals of a semiconductor device does not have a vacant terminal, not only a terminal dedicated to measurement cannot be added, but also the number of terminals is forcibly increased and the terminal pitch is changed. Then, there is a new problem that the printed wiring prepared on the user side cannot be used.

Referring to FIG. 8 described in Japanese Patent Application Laid-Open No. 2-132384, in which the number of terminals does not need to be increased, a substrate voltage generated internally due to a back bias of the semiconductor substrate 48 and the like is disclosed. In order to indirectly detect VBB, cells 44, 45, 46, each cell and substrate 48
, Two series-connected diodes, and three series-connected diodes 47, which are respectively connected between them.

According to this solution, a potential raised from the substrate voltage VBB by an integral multiple of the forward voltage of the diode 47 is applied to one end of each cell. Cell 44, cell 4
5 and 46, different voltages take different states (logical value 1 or 0) at a certain threshold value of the voltage applied from the voltage VBB. That is, digitized data is obtained according to the magnitude of the voltage VBB, and the state of this cell is read from the outside to estimate the value of the voltage VBB.

However, since it is not possible to provide a resolution within the forward voltage of one diode, it is not possible to detect the substrate voltage VBB with high accuracy, and it is also difficult to form the cells 44, 45, 46, the diode 47 and the like. Also in the case of (1), there is a problem that the substrate voltage VBB becomes defective and the reliability in inspection is low. In particular, since each cell alone is composed of six elements, a decrease in reliability at this point cannot be ignored. Further, in addition to the cell and the diode, a circuit for reading out digitized data to the outside is required, which causes a problem that the scale becomes large.

[0008]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has the following objects. (1) The potential of a predetermined region of a semiconductor substrate can be detected with high accuracy and high reliability by using an external terminal. (2) To be able to be shared with other terminals without adding a dedicated terminal for measurement. That is, the number of terminals and the terminal pitch of the semiconductor device need not be changed. (3) A circuit for outputting a potential of a predetermined region to a terminal has a very simple configuration.

[0009]

According to the present invention, a terminal electrically connected to each region of a semiconductor substrate covered by a package is led out of the package .
The predetermined region and the terminal are connected to each other by a resistance element so that the internal potential applied to the predetermined region of the semiconductor substrate can be measured.
Half, characterized in that it is electrically connected through a child
In the method for inspecting a conductor device, an external power supply is connected to the terminal.
Subsequently, when a voltage is applied to the terminal,
The voltage value of the external power supply when the power supply current stops flowing
Estimating the value of the internal potential by measuring
It is characterized by.

The power supply potential of the external power supply and the internal potential
The maximum value of the current flowing through the resistance element due to the potential difference
As a value smaller than the allowable maximum value of the defined leakage electric NagareTadashi rating value for said terminal, characterized in that the resistance value of the resistance element is adjusted.

Further, the internal potential of the predetermined region is a substrate potential of the semiconductor substrate.

Further , the terminal is an internal circuit of a semiconductor device.
Characterized in that it is connected so as to also serve as an output terminal from the input terminal or the 3-state buffer to the buffer is.

[0013]

[0014] The second solution of the present invention is a package.
Electrically connected to each area of the semiconductor substrate covered by the
Terminal is led out of the package, and
The internal potential applied to a predetermined area of the semiconductor substrate is measured.
The predetermined region and the terminal are connected to each other by a first resistor element.
A method for inspecting a semiconductor device, wherein the external power supply is connected to a second resistor element.
Through the children connected to the terminal, measuring the voltage value of the terminal
And a power supply voltage value of the external power supply and the first and second power supply voltages.
The ratio of the resistance value of the resistance element and the measured voltage value of the terminal
Is electrically connected via the first resistance element.
Characterized in that so as to estimate the internal potential of the predetermined regions are.

According to the solution of the present invention, the internal potential is
Since it is simply led out to the terminal via a resistor, the function of the conventional terminal part is not impaired, and the internal potential can be accurately detected. Become.

According to the first inspection method of the present invention, by measuring the external power supply voltage at the time when the power supply current stops flowing to the external power supply, it is possible to accurately estimate the potential of the corresponding predetermined area. According to the second inspection method, the internal potential is estimated from a ratio of a voltage value of an external power supply, a measured voltage value of the terminal, and a resistance value of the first and second resistance elements. Therefore, it is not necessary to adjust the voltage value of the external power supply at each point where the voltage value is measured, so that the inspection work can be performed more quickly.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIG. 1 showing a first embodiment of the present invention, this semiconductor device has an input terminal 1 serving as an external lead outside a package, and is formed on a semiconductor substrate in the package. An input terminal 1 is connected to an input of an input first stage 2 composed of a buffer circuit, and a power supply line 10 to which a potential of a predetermined region of an internal power supply generation circuit formed on a semiconductor substrate is applied via a predetermined resistor 3 And is connected between the input terminal 1 and the input first stage 2.

The internal power supply generation circuit 4 has a function of generating a voltage necessary for the circuit in a predetermined area in the semiconductor substrate based on a power supply voltage input from the outside. This circuit oscillates, boosts this oscillation output, and rectifies it to obtain a high voltage required for the circuit. If there are a plurality of circuits 4, the number of input terminals 1, input first stage 2, resistor 3, power supply line 1
0 is prepared.

The resistor 3 is preferably formed in a semiconductor substrate, but separately from the semiconductor substrate, as a single resistor,
It may be incorporated in the package.

The input terminal 1 serving as an external lead is electrically connected to a pad on the semiconductor substrate via the internal lead, directly or via a bonding wire, but is not shown.

The input terminal 1 is, for example, a lead to which a data signal is input, and is usually provided with a plurality of terminals. The potential of the power supply line 10 is detected by using this terminal 1. No data signal or the like is applied during the potential detection. Here, the input impedance of the first stage 2 is extremely large, and has a value that is at least one digit larger than the resistance 3.

Leakage current specified for input terminal 1
The maximum allowable value of the standard value and 10 .mu.A, assuming an input impedance of the input stage 2 is infinite, when the voltage across the resistor 3 a maximum 5V, by setting the resistance value of the resistor 3 above 500 k [Omega], an input terminal The value of the leak current flowing through the transistor 1 can be reduced to 10 μA or less.

Referring to FIG. 4 showing one measuring system for measuring the potential of the power supply line 10 in this circuit, an external power supply 17 for arbitrarily varying the voltage value and a connection between the external power supply 17 and the input terminal 1 are provided. And a voltmeter 19 that measures the voltage value of the external power supply 17. Although not shown, the ground terminals of the external power supply 17 and the voltmeter 19 are commonly connected to the semiconductor device under test and the ground terminal.

Referring to the flowchart of FIG. 6 showing the actual measurement procedure, first, the voltage of the external power supply 17 is appropriately applied to the input terminal 1, and then the current value is measured by the ammeter 20. It is determined whether or not the current is flowing in either direction. If the current is flowing, the voltage is varied to adjust the current so that the current does not flow. When the current stops flowing, the voltage of the external power supply 17 at that time becomes equal to the internal potential of the circuit 4, so that the voltmeter 19
By reading the display, you can measure immediately.

Here, since the voltage value when the current stops flowing to the ammeter 20 is measured, there is no fear that the measurement accuracy is reduced by the voltage drop due to the internal resistance of the ammeter 20, the resistor 3, and the like. There are advantages. The overall measurement accuracy in this case mainly depends on the measurement accuracy of the voltmeter 19 and the ammeter 20.

If the measured voltage value is within the allowable value, it is determined to be a good product. If the measured voltage value is outside the allowable value, it is discarded as a defective product, or only the circuit to which the voltage of the power supply line 10 is applied is used. It is used by taking advantage of other circuits without using it.

As described above, according to the internal potential detecting circuit and the detecting method of this embodiment, in the semiconductor device having a plurality of input terminals or input / output shared terminals, an internal power supply or an internal signal line is provided. And, between the input terminal or the I / O terminal, a resistor set to a value that is equal to or less than the input current value specified by the standard, and the input terminal or the I / O terminal is externally connected. By applying a voltage so that no current flows and measuring the potential at that time, the potential of the internal power supply or the internal signal line can be accurately detected.

Referring to FIG. 2 showing a second embodiment of the present invention, the internal circuit 8 and the signal lines 1 1 connected in common to 9, to connect the input terminal 5 via a resistor 7 West
Except that is the same as the first embodiment.

Referring to FIG. 3 showing a third embodiment of the present invention, an input / output terminal 16 to which a resistor 15 for detection is connected, and a three-state buffer 1 connected thereto.
Except that it includes a bi-directional buffer comprising a 2 and 18,
This is the same as the first embodiment.

The buffers 12 and 18 have control terminals 13 and 14, respectively, for setting the output to a high impedance state.

Prior to the measurement, the buffer 12 is set to a high impedance state. If the oscillation due to the positive feedback is a concern, the buffer 18 is also set to the high impedance state.

The procedure of measurement in this case is common to that of the first embodiment described above.

In the first, second, and third embodiments described above, the measurement system using the voltmeter 19 and the ammeter 20 in FIG. 4 has been described. In addition, the measurement system shown in FIG. Thus, the internal potential can be measured.

[0034] In FIG. 5, this measuring system, the voltmeter 19 to the terminal 1 is connected, via a resistor 21, the external power source 17 is connected. Here, the external power supply 17 is the case of FIG.
It needs to be adjusted for each measurement as is not the name. Further, when the resistance value of the resistor element 21, and the same resistance <br/> anti values and the resistance element 3, 7 or 17, the estimated voltage values of the internal power position is
Be obtained from a simple calculation formula (2 × VI-VO)
Wear. Here , VI is the voltage value of the voltmeter 19, and VO is the voltage value of the external power supply.

According to this embodiment, there is an advantage that it is not necessary to adjust the external power supply 17.

[0036]

As described above, according to the present invention, a dual-purpose terminal to which a resistor is connected is provided, and the internal potential can be measured by the dual-purpose terminal, so that it is not necessary to newly provide a dedicated terminal. , And without the need to add large circuits,
All of the above-mentioned tasks have been achieved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a circuit diagram showing a second embodiment.

FIG. 3 is a circuit diagram showing a third embodiment.

FIG. 4 is a circuit diagram showing one measuring system of each embodiment of the present invention.

FIG. 5 is a circuit diagram showing another measurement system of each embodiment of the present invention.

FIG. 6 is a flowchart showing the operation of one measurement system.

FIG. 7 is a circuit diagram for detecting a conventional internal potential.

FIG. 8 is a circuit diagram for detecting an internal potential using a conventional memory cell.

[Explanation of symbols]

 1,5 input terminal 2,6 input first stage 3,7,15,21 resistor 4,33 internal power generation circuit 8,9 internal circuit 10 power line 11 signal line 12,18 three-state buffer 13,14 high impedance control terminal 16 Input / output terminal 17 External power supply 19 Voltmeter 20 Ammeter 31 Output terminal 44, 45, 46 Cell 47 Diode 48 Board

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) G01R 31/28-31/3193 G11C 29/00 H01L 21/822 H01L 27/04

Claims (6)

(57) [Claims] [Claim 1] Each region of the semiconductor substrate covered with the package and electrically connected to the terminals are led out of the package, the internal potential applied to a predetermined region of the semiconductor substrate can be measured As described above, in the semiconductor device inspection method, the predetermined region and the terminal are electrically connected via a resistance element.
Is connected to the terminal and when voltage is applied,
When the power supply voltage of the power supply is varied and the power supply current stops flowing
By measuring the voltage value of the external power supply at the time of
A semi-characteristic wherein the value of the internal potential is estimated.
Inspection method of conductor device. 2. The power supply potential of the external power supply and the internal potential
Maximum value of the current flowing through the resistance element due to the potential difference between
But, as a value smaller than the allowable maximum value of the defined leakage electric NagareTadashi rated value for the terminal, a method of inspecting a semiconductor device according to claim 1, wherein the resistance value of the resistance element is adjusted. 3. A method of inspecting the resistance value of the resistive element, the semiconductor device according to claim 1 or claim 2 wherein the so is above 500 k [Omega]. 4. The method according to claim 1, wherein the internal potential of the predetermined region is a substrate potential of the semiconductor substrate. 5. The terminal according to claim 1, wherein the terminal is an internal circuit of the semiconductor device.
That input terminal or the three-state buffer to buffer
5. The semiconductor device inspection method according to claim 1 , wherein the semiconductor device is connected so as to also serve as an output terminal from the semiconductor device. 6. Each area of a semiconductor substrate covered by a package.
Terminals electrically connected to the package are located outside the package.
And applied to a predetermined region of the semiconductor substrate.
The predetermined area and the
The terminal is electrically connected via the first resistance element.
An external power supply is connected to the terminal via a second resistive element, and a voltage value of the terminal is
Measuring the power supply voltage value of the external power supply,
And the measured voltage of the terminal.
From the value, electrically connected via the first resistance element.
And estimating an internal potential of the predetermined region .