JP2003185711A - Inspection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To inspect an internal circuit of an integrated circuit or a condition of an I/O pin thereof, using the minimum of inspection probes. <P>SOLUTION: In this device, switch means 57, 59 are provided to connect analog test buses 41, 42 included in the integrated circuit selectively to the internal circuit 2 or the I/O pin, the connection of the switch means is controlled in response to a control signal, and switches for a pair of analog test buses are connected to an I/O pad 43 via resistances 22-24 respectively, in the switch means connected to the I/O pad 43. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor integrated circuit inspection device.

[0002]

2. Description of the Related Art A conventional circuit inspection method is an effective inspection method for efficiently diagnosing a fault location by inspecting a wiring or a component of a printed circuit board on which a component is mounted by contacting an inspection probe. Is used as. For component inspection on a mounting board, for example, an analog IC has a relatively small number of pins, and it is comparatively easy to bring an inspection probe into contact with a test point provided on a printed circuit board and observe its output signal. I was able to carry out the inspection.

[0003]

[Non-Patent Document 1] "Integrating design and Test: Usi
ng CAE Tools for ATE Programming ”, KPParker, IEEE
Computer Society Press, Los Alamitos CA, 1987

[0004]

However, with the recent miniaturization and higher functionality of electronic equipment, higher integration of ICs,
High-density mounting of printed circuit boards is rapidly advancing.
For this reason, the circuit inspection method using the inspection probe has lost its usefulness. In addition to the high density of the mounting board, high integration, or the increased number of pins due to mixed integration with a digital IC makes it difficult to bring the inspection probe into contact, and inspection of the analog IC has become difficult. .

The present invention relates to an internal circuit of an integrated circuit or I
An object of the present invention is to provide an inspection device for an integrated circuit that inspects the status of the / O pin with a minimum inspection probe.

[0006]

In order to solve this problem, the present invention provides a pair of first and second analog test buses included in an integrated circuit and an internal circuit or an I / O circuit for the pair of analog test buses. The switch means has a switch means selectively connected to the O pin and a switch control means for controlling connection of the switch means according to a control signal. In the switch means, the switch means connected to the I / O pad is the above-mentioned. The switch of the pair of analog test buses is connected to the I / O pad via a resistor, respectively.

[0007]

FIG. 1 shows a part of an integrated circuit to which an embodiment of the present invention is applied. In FIG. 1, 2
Is an internal circuit having the original function of the integrated circuit, 21 is a model of wiring resistance, 22, 23 and 24 are protective resistances, 3
Reference numerals 4 and 35 are I / O pads, and 36 and 37 are protection transistors. 41 and 42 are analog test buses and 57 and 5
9 is a switch means. It should be noted that wiring and the like not related to the description are omitted in the drawing.

In manufacturing an integrated circuit, as an example, when the physical distance between the switch means 57 and the I / O pad 43 is long, a wiring resistance 21 may occur between the switch means 57 and the I / O pad 43. is there. Due to the resistance component of the wiring resistance 21, when measuring the potential outside the I / O pad 34 using the analog test bus 41, a measurement error occurs if the wiring resistance is not sufficiently smaller than the external load resistance. Therefore, a protective resistor 2 is provided between the I / O pad and each analog test bus or the wiring to the internal circuit, such as between the switch means 59 and the I / O pad 35.
2, 23, 24 are provided.

Thus, for example, the analog test bus 41
When measuring the potential of the I / O pad 35 with, the internal resistance of the voltmeter is usually several megohms or more.
Even if 2 is 1 kilohm, the error is about 1%. By intentionally providing a protective resistor as shown in the figure, errors during measurement can be practically eliminated, and the test circuit itself such as the analog test bus and switch means can be protected from external surge voltage, etc. .

FIG. 2 shows an I to which an embodiment of the present invention is applied.
/ O pad is shown. 2 and 2 in FIG.
3 and 24 are protection resistors, 25 is a model of the resistance component of the I / O pad, and 35 is an I / O pad.
In FIGS. 2B and 2C, 22 is a protective resistor, 201 is a first aluminum wiring, 202 is a second aluminum wiring, 203 is a silicon dioxide layer, and 204 is a silicon substrate.

In FIG. 2C, 205 is a diffusion layer and 206
Is a third aluminum wiring, and 207 is a wiring to the analog test bus. It should be noted that wiring and the like not related to the description are omitted in the drawing.

2 (a) and 2 (b) show the I / O pad 3 of FIG.
5 shows an enlarged view of the vicinity of No. 5 and its physical sectional view. Figure 1
Although the advantage of providing the protective resistance around the I / O pad 35 has been described above, in a microscopic sense, aluminum is provided between the bonding portion at the center of the I / O pad and the analog test bus or the wiring to the internal circuit. Since there is a slight resistance component 25 of the wiring, the resistance of this portion may cause an error during measurement in some cases.

FIG. 2C is an improvement of the portion near the I / O pad of FIG. 2B. A hole is formed in the silicon dioxide layer 203 immediately below the bonding portion and in the wiring portion to the analog test bus or the internal circuit, and the silicon substrate 2 is formed.
A diffusion layer is generated at 04. Aluminum wiring is provided in a hole formed in a wiring portion to the analog test bus or the internal circuit, and wiring to the analog test bus or the internal circuit is performed.

Thus, the voltage measurement by the analog test bus can be performed more accurately than the center of I / O pad bonding. Further, since the diffusion layer 205 has a resistance component, the protection resistors 22, 23, and 24 which are conventionally intentionally provided are provided.
It becomes unnecessary to provide.

[0015]

As described above, according to the present invention, it is possible to reduce the influence of the resistance of the switch on the measurement system during measurement using the analog test bus.

Further, the I / O pad is connected from the center of the pad to the conductor connected to the second analog test bus for connecting the measuring device of the pair of analog test buses via the resistor or the conductor, The effect of the switch resistance on the measurement system during measurement using the analog test bus can be further reduced.

[Brief description of drawings]

FIG. 1 is a structural diagram of an integrated circuit according to an embodiment of the present invention.

FIG. 2 is a structural diagram of an I / O pad according to an embodiment of the present invention.

[Explanation of symbols]

2 Internal circuit 22,23,24 Protective resistance 34,35 I / O pad 41,42 Analog test bus 57,59 switch means

Claims (2)

[Claims] 1. An apparatus for measuring a status of an internal circuit and an status of an I / O pin of an integrated circuit, comprising first and second pair of analog test buses included in the integrated circuit, and the pair of analogs. The test bus is connected to the internal circuit or the I
A switch means selectively connected to the / O pin and a switch control means for controlling the connection of the switch means in response to a control signal. In the switch means, the switch means connected to the I / O pad is An inspection apparatus in which switches of the pair of analog test buses are connected to I / O pads via resistors, respectively. 2. The I / O pad is connected from the center of the pad to a conductor connected to a second analog test bus connecting a measuring device of the pair of analog test buses via a resistor or a conductor. The inspection apparatus according to claim 1.