JPH02112261A - Semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To improve the characteristics of the device resistant to power supply noise to an IC by reducing bad affection to electric performance of a function block inspected and resisting an increase of the number of pins disposed in the IC by providing a fuse at a joint between an internal test auxiliary circuit and another section for functioning the test circuit. CONSTITUTION:A function block 2 to be inspected in its electrical performance is connected to a test auxiliary circuit 2 through a fuse 4 at an output point 5 thereof. The function block 2 is inspected in the electrical performance by the test auxiliary circuit 5 on the basis of an output on the output point 5 of the function block 2. After the inspection is completed, the fuse 4 is fused by a laser beam, etc., electrically disconnect the function block 2 from the test auxiliary circuit 3. Hereby, an influence of capacitive load of the test auxiliary circuit 3 onto the function block 2 is reduced to improve the electrical performance of the function block 2. For example with the function block 2 being a RAM, the leading and trailing edges of an output waveform from the same are increased, thereby shortening the access time upon using the RAM.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a semiconductor integrated circuit device (Ic), and in particular,
This invention relates to improving the electrical performance of an IC during IC operation.

[Prior Art] Semiconductor integrated circuit devices (ICs) have a so-called test auxiliary circuit installed inside them in order to test whether the internal functional blocks are able to realize the intended functions and to test their electrical performance. Contains.

FIG. 4 is a diagram showing how the test auxiliary circuit in the IC chip and the functional block to be tested are connected when testing electrical performance such as memory access time of the functional block in the IC chip. . In the figure, a functional block 2 embedded in an IC chip 1 is connected to a test auxiliary circuit 3 at an output point 5 of the functional block 2. The electrical performance of the functional block 2 is tested by the output from the output point 5 of the functional block 2 using the test auxiliary circuit 3.

FIG. 5 is a diagram illustrating the parts involved in testing to determine whether or not the functional blocks within the IC chip are achieving the originally desired functions. In the figure, the test to determine whether the functional block 7 in the IC chip 6 is achieving the desired function is to apply a predetermined voltage to the power supply pad 10 (
For example, after applying 5V) and grounding the GND pad 14, the test auxiliary circuit 7 is controlled by a control signal sent to the external signal pad 9.

[Problems to be Solved by the Invention] In the IC having the configuration as shown in FIG. There is a problem in that the electrical characteristics such as the pulse drive capability of the functional block 2, which is originally desired to be realized in the IC, are inhibited by the capacitive load.

In the IC having the configuration shown in FIG. 5, the external signal pad 9 is connected to the test auxiliary circuit 8 which is no longer needed even after the test of the functional block 7 is completed.

Therefore, even after the test is completed, the test auxiliary circuit signal pins remain between the test auxiliary circuit and the external signal pad, and the number of pins within the IC continues to increase. On the other hand, in order to improve the power supply noise resistance characteristics during IC operation, it was necessary to increase the number of power supply pins, which resulted in a further increase in the number of pins within the IC. However, the increase in the number of IC pins hinders the improvement of IC packaging density.
There was a problem that I didn't like it.

The purpose of the present invention is to solve the above-mentioned problems and to provide an IC that achieves the improvement in the electrical characteristics of the functional blocks that the IC originally desires to realize, and an IC that can suppress the increase in the number of bins in the IC.
The goal is to develop an IC that can improve the power supply resistance characteristics of the fJ and strengthen the power supply system to the IC.

[Means for Solving the Problems] In order to solve the two problems as described above, the I
C uses a fuse in the connection between the internal test auxiliary circuit and other parts that make the test auxiliary circuit function. That is, after the required test is completed, by cutting the fuse by some means, it is possible to electrically disconnect the test auxiliary circuit inside the IC from other parts connected via the fuse that make the test auxiliary circuit function. It has been made possible.

[Operation] In the IC configured as described above, by using a fuse between the test auxiliary circuit and the functional block to be tested by it, the test auxiliary circuit that is no longer needed after the test is completed can be removed from the functional block. Can be electrically disconnected. Therefore, unlike conventional ICs, the electrical performance of the functional parts that the IC originally wants to achieve does not deteriorate due to the negative 6:j capacitance of the test auxiliary circuit, and the electrical performance of the functional parts that the IC originally wants to achieve is improved. Ru.

In addition, when testing a functional block by applying a predetermined voltage to the power supply pad and GND pad during tC, the test can be performed by using a fuse between the test auxiliary circuit and the external signal pad for controlling it. External signal pads that are no longer needed after testing can be separated from the test auxiliary circuit. Therefore, if an appropriate circuit is prepared between the power supply pad or GND pad and the external signal pad, the test auxiliary circuit signal pin of the external signal pad can be set to a voltage equal to the power supply voltage or GND voltage. I can do it. This means that the number of power supply bins or GND pins has been increased without increasing the number of bins in the IC, which results in lower impedance of the power supply or GND, and the IC
This means that the power supply system has been strengthened.

[Embodiment] FIG. 1 is a diagram showing the connection between functional blocks in an IC chip and a test auxiliary circuit according to an embodiment of the present invention. In the figure, a functional block 2 whose electrical performance is to be tested is connected via a fuse 4 at its output point 5 to a test auxiliary circuit 2 . The electrical performance of the functional block 2 is tested by the output of the output point 5 of the functional block 2 using the test auxiliary circuit 3, as in the prior art. After the test is completed, the fuse 4 is fused with a laser beam or the like to electrically disconnect the functional block 2 from the test auxiliary circuit 3. As a result, the influence of the capacitive load of the test auxiliary circuit 3 on the functional block 2 is reduced, and the electrical performance of the functional block 2 is improved. For example, if the functional block 2 is a RAM, the rise and fall of its output waveform will be faster, and the RAM
Access time during use becomes faster.

FIG. 2 is a diagram schematically showing the inside of an IC chip according to another embodiment of the present invention. A test auxiliary circuit 8 within the IC chip 6 is connected between the functional block 7 to be tested and an external signal pad 9 via a fuse 4a. The transistor 12 is external (.

The power supply line 15 is connected between the number pad 9 and the power supply line 15 connected to the power supply pad 10 . Voltage generating circuit 11 is connected between GND line 13 and power supply line 15 , and yet another high potential side terminal of voltage generating circuit 11 is connected to the gate of transistor 12 . Further, a connection point between voltage generation circuit 11 and transistor 12 is connected to GND line 13 via fuse 4b. The inspection of the functional block 7, which should be inspected to see if it realizes the originally desired function, is carried out using the power supply pad 10, as in the case of the prior art.
After applying a predetermined voltage to and grounding the GND pad 14,
Test auxiliary circuit 8 from external signal pad 9! This is done by controlling with a control signal that is input. After the test path, the fuse 4a is blown by a laser beam or the like to electrically disconnect the external signal pad 9 from the test auxiliary circuit 8.

Next, the fuse 4b is also blown by a laser beam or the like.

As a result, a potential higher than the potential of the power supply line 15 is supplied from the voltage generating circuit 11 to the gate of the transistor 12, and the transistor 12 becomes conductive. As a result, the potential of the node]6 becomes the same as the potential of the power supply line 15. This means that the external signal pad 9, which had the function of supplying a control signal to the test auxiliary circuit 8 when testing the functional block 7, plays a role equivalent to the power supply pad 10.

In other words, the test auxiliary circuit pin of external signal pad 9 becomes the fJ577fA pin, and the number of pins inside the IC does not increase, but the number of power supply pins increases from one to two, and the low impedance of the power supply reduces power supply noise resistance during IC operation. can be strengthened.

FIG. 3 is a diagram schematically showing the inside of an IC chip according to still another embodiment of the present invention. Tess inside IC chip 6]
- The auxiliary circuit 8 is connected between the functional block 7 to be tested and the external signal pad 9 via a fuse 4b.

Transistor 12 connects external signal pad 9 and GND pad 1
4. Power supply line 15 is connected to the gate of transistor 12 via resistor 17. Furthermore, the connection point between the resistor 17 and the transistor 12 is connected to the GND line 1.
Connected to 3. The inspection of the functional block 7 whose electrical performance is to be inspected and the blowing of the fuse 4a after the inspection are carried out in the second
This is carried out in the same manner as in the case of the IC shown in the figure, and test auxiliary circuit 8 and external signal pad 9 are electrically separated. Next, the fuse 4b is also blown by the laser beam t17. As a result, a potential higher than that of the GND line 13 is applied to the gate of the transistor 12 by the power supply line 15 (j
E is supplied, and the transistor 12 becomes conductive. As a result, the potential of the node 18 becomes equal to the potential of the GND line 13. This means that, contrary to the case of the embodiment shown in FIG. 2, the external pad 9 plays a role equivalent to the GND pad. That is, Tess of external signal bad 9!・The auxiliary circuit bin becomes the GND pin. Therefore, the number of pins in the IC does not increase, and the number of GND pins increases from one to two.
By reducing the impedance of GND, the resistance to GND noise to the IC can be strengthened.

In the above embodiments, a laser beam is used as a means for blowing the fuse, but electrical means may also be used. Further, in the above embodiment, only the case where the test auxiliary circuit is separated is shown, but the tC It is possible to improve the electrical performance of the functions originally desired.

[Effects of the Invention] As described above, according to the present invention, a functional block whose electrical performance has been tested using the test auxiliary circuit due to the capacitive load of the test I/auxiliary circuit that is no longer needed as in the past. The negative impact on electrical performance can be reduced. Furthermore, since the test auxiliary circuit pin can be electrically converted into a power supply pin or a GND pin, the power supply resistance and GND noise resistance during IC operation are enhanced. in this way,
By using the Ic according to the present invention, the electrical performance of the IC is improved.

[Brief explanation of the drawing]

] 0 FIG. 1 is a diagram schematically showing the internal configuration of an IC chip according to one embodiment of the present invention, and FIG. 2 is a diagram schematically showing the internal configuration of an IC chip according to another embodiment of the present invention. , FIG. 3 is a diagram schematically showing the internal configuration of an IC chip according to yet another embodiment of the present invention, and FIG. 4 is a diagram schematically showing the internal configuration of an IC chip according to an embodiment of the prior art. , FIG. 5 shows I of another embodiment of the prior art.
FIG. 3 is a diagram schematically showing the configuration inside the C chip. In the figure, 1 and 6 are IC chips, 2 and 7 are functional blocks, 3 and 8 are test auxiliary circuits, 4, 4a and 4b are fuses, 5 is an output point of functional block 2, and 9 is an external signal. Pad, 10 is a power supply rose!・, 11 is a voltage generation circuit, 12 is a transistor, 1
3 is a GND line, 14 is a GND pad, 15 is a power supply line, and 17 is a resistor. In addition, are the images the same? The C symbol indicates the same or equivalent part.

Claims (1)

[Scope of Claims] A semiconductor integrated circuit device, comprising: a functional section that achieves a function to be realized by the semiconductor integrated circuit device; a test circuit section that tests the function of the functional section; and a test circuit section that tests the function of the functional section. 1. A semiconductor integrated circuit device, comprising fuse means which are electrically connected to function and which are to be blown to disable said test circuit section after completion of a required test.