JPH09113566A - Connected state detecting device for semiconductor substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a detecting device that can detect the connected state of bonding wires of a semiconductor substrate. SOLUTION: In the case of bonding wires 13a-13d being normally connected, a current flows through paths reaching a lead 15 from the bonding wires 13a-13d, starting from an internal circuit 17 via a reference point 9, wiring resistances 19a-19d, bonding pads 3a-3d, and the potential of the reference point 9 becomes larger than the potential of the bonding pads 3a-3d, so that the output of comporators 11a-11d are all in a high state. In the case of the bonding wire 13a being severed, on the other hand, a current does not flow through the path reaching the lead 15 from the bonding wire 13a, starting from the internal circuit 17 via the reference point 9, the wiring resistance 19a and the bonding pad 3a, so that the reference point 9 and bonding pad 3a are equal in potential, and the output of the comparator 11a is in a low state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor substrate connection state detecting device capable of detecting a connection state of a bonding wire of a semiconductor substrate.

[0002]

2. Description of the Related Art As a conventional semiconductor substrate connection state detecting device, for example, a device shown in FIG. 9 is known. In the figure, the internal circuit 1 is formed on the semiconductor substrate 100.
A plurality of bonding pads 101 connected to one terminal 11 are formed, and the plurality of bonding pads 1 are formed.
01 The two are electrically connected by the first metal wiring 103.
Then, one point on the first metal wiring 103 and the internal circuit 11
The first metal wiring 105 is electrically connected to one terminal of No. 1. As the wiring, in addition to metal, for example, a diffusion layer or polysilicon can be used. Then, the plurality of bonding pads 101 and electrodes outside the semiconductor substrate, for example, one lead 109 of the package are connected to the bonding wire 10.
7 and electrically connect to perform multi-wire bonding. The electrodes outside the semiconductor substrate include electrodes outside the bare chip.

[0003]

Generally, since the amount of current that can flow in the bonding wire 107 is limited, it is necessary to use a plurality of bonding wires when the amount of current is insufficient with one bonding wire.
However, in the case of performing multi-wire bonding, if even one of the bonding wires 107 is broken, current concentration occurs in the remaining bonding wires 107 in the connected state, which makes it easy to break the wires. In addition, since the necessary amount of current does not flow, there is a problem that the ground level floats when the lead using the bonding wire 107 is ground, and as a result, the internal circuit on the semiconductor substrate may not operate normally. there were.

Therefore, it is necessary to perform a disconnection inspection for confirming the connection state of the bonding wire 107. In the disconnection inspection process, visual inspection or electrical connection inspection by an operator has been conventionally performed. However, in the visual inspection by the operator, as shown in FIG. 10, when one side of the bonding wire 107 completely floats and is separated from the bonding pad 101, the disconnection portion can be confirmed, while FIG. In the case of the disconnection state as shown in FIG. 11B, there is a possibility that it may be overlooked only by visually observing it from the upper surface as shown in FIG. 11B. However, since visual inspection cannot be performed after the semiconductor substrate is packaged, the only option is to rely on electrical inspection.

Also in the case of an electrical connection inspection, which lead 109 is detected by passing a current from the bonding pad 101 to the lead 109 and detecting a subtle change in the amount of current.
Since it was only necessary to determine whether or not a slight change in the amount of current occurred, it was difficult to specify which bonding wire 107 was broken.

Furthermore, in the inspection combining the electrical connection inspection and the visual inspection, for example, as shown in FIG. 10, when the electrical resistance between the bonding pad 101 or the second metal wiring 105 and the lead 109 is measured. If one of the bonding wires 107 is broken like a broken wire, the electrical resistance is increased accordingly, so that the lead having the increased electrical resistance can be identified first, and then a visual inspection is performed to determine which bonding is performed. It was specified whether the wire 107 was broken. Therefore, the inspection that combines the electrical connection inspection and the visual inspection requires an extremely long inspection time.

As described above, in the conventional semiconductor substrate connection state detecting device, since only the bonding pads connected by the metal wiring are formed on the semiconductor substrate, multi-wire bonding is performed. After
There is a problem that the inspection efficiency cannot be improved because the operator visually or inspects the electrical connection in the disconnection inspection process. In particular, since visual inspection cannot be performed after the semiconductor substrate is packaged, it has to rely on electrical inspection, which not only takes a lot of time, but also leads to an increase in cost. On the other hand, it is possible to improve the yield that indicates the ratio of non-defective products. There was a problem that it could not be done.

[0008] The present invention has been made in view of the above,
It is an object of the present invention to provide a semiconductor substrate connection state detection device capable of detecting the bonding wire connection state of a semiconductor substrate.

[0009]

According to the first aspect of the present invention,
In order to solve the above-mentioned problems, a plurality of bonding pads are connected from a reference point connected to an internal circuit through a plurality of wirings, and the plurality of bonding pads are respectively connected to leads using a plurality of bonding wires. A semiconductor substrate connection state detection device for inspecting a connection / disconnection state of the plurality of bonding wires with respect to a semiconductor substrate, wherein the connection state of the plurality of bonding wires connected to the plurality of bonding pads and the leads is detected. The gist is to have a connection state detecting means for detecting.

According to the first aspect of the present invention, the reference point connected to the internal circuit is connected to a plurality of bonding pads via a plurality of wirings, and the plurality of bonding pads are connected to leads by using a plurality of bonding wires. By detecting the connection state of a plurality of bonding wires connected to a plurality of bonding pads and leads to the connected semiconductor substrate, it is possible to detect that each of the plurality of bonding wires is in a connected / disconnected state. Have.

In order to solve the above problems, the connection state detecting means detects the connection state of the plurality of bonding wires based on a potential difference between the plurality of bonding pads and the reference point. The point is to do.

According to the second aspect of the present invention, the reference point connected to the internal circuit is connected to a plurality of bonding pads via a plurality of wirings, and the plurality of bonding pads are used as leads by using a plurality of bonding wires. By detecting the connection status of multiple bonding wires based on the potential difference between multiple bonding pads and the reference point for the connected semiconductor substrate, it is possible to detect that each of the multiple bonding wires is in the connected or disconnected state. Has the effect of

In order to solve the above-mentioned problems, the invention according to claim 3 is characterized in that the connection state detecting means has a selecting means for selecting one of the potentials of the plurality of bonding pads.

According to a third aspect of the present invention, a reference point connected to the internal circuit is connected to a plurality of bonding pads via a plurality of wirings, and the plurality of bonding pads are used as leads by using a plurality of bonding wires. By selecting one of the potentials of a plurality of bonding pads for the semiconductor substrate to be connected, and then detecting the connection state of the bonding wire based on the potential difference between the bonding pad and the reference point, the bonding It has an effect of detecting that the wire is in the connected / disconnected state.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a semiconductor substrate connection state detection device according to a first embodiment of the present invention.
In the figure, the semiconductor substrate 1 has a reference point 9 connected to an internal circuit 17 on the semiconductor substrate 1 via a metal wiring 7,
A plurality of metal wirings 5a to 5d having a resistance component for connecting the reference point 9 and the plurality of bonding pads 3a to 3d,
A plurality of metal wirings 5a to 5 having a resistance component from the reference point 9
It is composed of a plurality of bonding pads 3a to 3d for performing multi-wire bonding connected via d.

In the figure, the bonding wire 13a
13d are leads 15 and bonding pads 3a-3.
The lead 15 is a bonding wire for electrically connecting to d, and the lead 15 is an electrode arranged in a package outside the semiconductor substrate and connected from the plurality of bonding pads 3a to 3d using the plurality of bonding wires 13a to 13d, respectively. Is.

In the figure, comparators 11a to 11
In d, the two input terminals are connected to the reference point 9 and the respective bonding pads 3a to 3d to detect the potential difference between the input terminals. The comparators 11a to 11d output a "High" state when the input voltage is, for example, non-inverting input terminal> inverting input terminal, and "Low" when the non-inverting input terminal = inverting input terminal. Output status. It is assumed that the comparators 11a to 11d are arranged on the semiconductor substrate 1.

Next, the operation of this embodiment will be described with reference to FIG. FIG. 2 is an equivalent circuit of the first embodiment shown in FIG. The lead 15 will be described as a ground pin here. Further, the wiring resistors 19a to 19d are
The wiring resistance of the metal wirings 5a to 5d is shown. First, when all the bonding wires 13a to 13d are normally connected, the internal circuit 17 causes the reference point 9,
Wiring resistances 19a to 19d, bonding pads 3a to 3
A current flows through the path from the bonding wires 13a to 13d to the lead 15 via d. In this case, since a potential difference is generated between the reference point 9 and the bonding pads 3a to 3d due to the wiring resistances 19a to 19d, the potential of the reference point 9> the potential of the bonding pads 3a to 3d and the outputs of the comparators 11a to 11d are All “H
and the bonding wires 13a to 13 are turned on.
It can be detected that d is connected.

On the other hand, if the bonding wire 13a is broken, for example, a current flows from the internal circuit 17 through the reference point 9, the wiring resistance 19a, and the bonding pad 3a to the bonding wire 13a to the lead 15. Since it does not flow, the potential of the reference point 9 = the potential of the bonding pads 3a to 3d Since the reference point 9 and the bonding pad 3a have the same potential, the output of the comparator 11a becomes "Low" and the bonding wire 13a is disconnected. Can be detected.

Here, the potential difference when the potential difference is generated at both ends of the metal wirings 5a to 5d is the comparators 11a to 11d.
The resistance value of the metal wirings 5a to 5d located between the reference point 9 and the bonding pads 3a to 3d is set so as to be larger than the variation of the offset voltage of.

For example, the bonding wires 13a-13
When d is a gold wire with a diameter of 35 μm, a current of about 1.6 A can be applied to each wire, so if the sheet resistance of the metal wirings 5a to 5d is 19 mΩ and the line width is 70 μm. , The metal wirings 5a to 5d each have a length 138.
With a wiring length of about μm, a potential difference of about 60 mV causes a metal wiring 5
It occurs at both ends of a to 5d.

Next, FIG. 3 is a diagram showing an example of an internal circuit of a MOS comparator composed of MOS transistors. As shown in the figure, the MOS comparator comprises a Pch differential amplification stage of a current mirror load and a source ground voltage amplification stage of a current mirror load, and an inverter is added to the final stage. The non-inverting input terminal V + is on the M5 side, and the inverting input terminal V- is on the M6 side. Here, the offset voltage of the MOS comparator is M5, M
Since it is determined by the size of the transistor used for 6, the offset voltage of the MOS comparator is 0V when the same size transistors are used for M5 and M6. Further, as shown in the figure, since the MOS comparator is arranged on the semiconductor substrate 1, the disconnection inspection can be performed accurately and quickly, so that the time can be significantly shortened and the cost can be reduced.

Next, FIG. 4 shows the operation when the non-inverting input terminal V + is changed from 0V to 5V while the inverting input terminal V- on the M6 side of the MOS comparator shown in FIG. 3 is set to a constant 0V. It is a graph which shows an example of analysis. Also, FIG.
5 is an enlarged graph showing an intersection (C) of the input waveform (A) and the output waveform (B) shown in FIG. 4. 4 and 5
Shows that the width of the transistor M5 shown in FIG. 3 is increased by about 10% as compared with the case where the offset voltage is 0V, and the output is "Low" when the input potential of the non-inverting input terminal V + is about 32.5mV. The state has changed to the "High" state. That is, the offset voltage of the MOS comparator 11 is 32.5 mV.

Here, the variation in the offset voltage of the comparator using the MOS structure is generally ± 20 mV.
Considering that, if the input voltage of the non-inverting input terminal V + is lower than at least 12 mV, the state is “Low”, while if the input voltage of the non-inverting input terminal V + is higher than 53 mV, the state is “High”. Become. Therefore, if the potential difference between both ends of the metal wiring 5a when the bonding wire 13a is connected as described above is about 60 mV and the potential difference when the wire is disconnected is 0 mV, the comparator 11
The disconnection state can be detected by. Further, when the bonding wire 13a is connected, the output of the comparator 11 is in the "High" state, while when it is disconnected, the output of the comparator 11 is in the "Low" state.

When the comparator 11 is constructed by using the bipolar structure, it is possible to realize a smaller offset voltage variation. Therefore, even if the metal wirings 5a to 5d are thick and the wiring resistance is lower. It is possible to detect disconnection.

Therefore, the disconnection detection of the multi-wire bonding can be easily performed electrically, and the disconnection detection can be performed more accurately and faster than the conventional visual inspection or electrical connection inspection. Further, the detection result can be confirmed by taking out the result signal obtained by detecting the disconnection state by the comparator 11 as it is. Furthermore, by returning the result signal to the internal circuit 17, it can be used as a fail-safe for stopping the circuit function of the semiconductor substrate when the bonding wire is broken.

Next, FIG. 6 is a diagram showing a semiconductor substrate connection state detecting device according to a second embodiment of the present invention.
The feature is that, as shown in FIG. 6, a multiplexer 21 is provided between the plurality of bonding pads 3a to 3d and the comparator 11 to switch wirings from the plurality of bonding pads 3a to 3d. As a result, the number of comparators 11 connected to the plurality of bonding pads 3a to 3d can be reduced to one, and the area of the device can be reduced.

Next, FIG. 7 is a diagram showing a third embodiment of a semiconductor substrate. In the figure, the semiconductor substrate 1 is
A wide metal wiring 7 connected to the internal circuit 17 on the semiconductor substrate 1, a reference point 9 existing in the metal wiring 7 and connected to the non-inverting input terminal of the comparator 11, the metal wiring 7 and a plurality of bondings. A plurality of metal wirings 5a to 5c having a resistance component respectively connecting to the pads 3a to 3c
And a plurality of metal wirings 5 having a resistance component from the metal wirings 7.
a to 5c, and a plurality of bonding pads 3a to 3c for performing multi-wire bonding.

As described above, by laying out the wide metal wiring 7 on the semiconductor substrate 1, no matter where the reference point 9 is provided, the potential difference due to the difference in the position of the reference point 9 does not occur, and it is provided on the semiconductor substrate 1. The design of the comparator 11 is facilitated, and when the reference point 9 is provided on the metal wiring 7, the comparator 11 may be designed by considering only the potential difference generated by the wiring resistance of the metal wirings 5a to 5c. The degree of freedom in layout can be expanded while maintaining the accuracy of.

Next, FIG. 8 is a diagram showing a fourth embodiment of the semiconductor substrate. In the figure, the semiconductor substrate 1 is
A wide metal wiring 7 connected to the internal circuit 17 on the semiconductor substrate 1, a reference point 9 existing in the metal wiring 7 and connected to the non-inverting input terminal of the comparator 11, the metal wiring 7 and a plurality of bondings. A plurality of metal wirings 5a to 5c having a resistance component respectively connecting the pads 3a to 3c and a plurality of metal wirings 5a to 5 having a resistance component from the metal wiring 7
It is composed of a plurality of bonding pads 3a to 3c for performing multi-wire bonding connected via c.

In this way, by laying out the wide metal wiring 7 on the semiconductor substrate 1 so as to surround the plurality of bonding pads 3a to 3c, no matter where the reference point 9 is provided, the position of the reference point 9 is different. The generation of the potential difference due to the generation is eliminated, the design of the comparator 11 provided on the semiconductor substrate 1 is facilitated, and the design of the comparator 11 when the reference point 9 is provided on the metal wiring 7 is performed by wiring the metal wirings 5a to 5c. It suffices to consider only the potential difference generated by the resistance,
The degree of freedom in layout can be expanded while the accuracy of the comparator 11 remains high.

As described with reference to FIGS. 1, 6, 7, and 8, the metal wiring 5 and the metal wiring 7 have the following two configurations.
The feature of the present invention is that it is established under the conditions of the items. ◎ Firstly, the difference in the potential difference generated between the reference point 9 and the bonding pad 3 between when the bonding wire 13 is broken and when it is connected is set to be larger than the variation in the offset voltage of the comparator 11. It is to be.

Second, each metal wiring 5 is set so that the potential difference generated between the reference point 9 and the bonding pad 3 when the wiring is broken except for the common wiring resistance portion is smaller than the negative variation. On the other hand, the potential difference generated between the reference point 9 and the bonding pad 3 when connected is set to be larger than the positive variation.

By configuring the comparator 11 as in the first and second conditions, the connection state of the bonding wires on the semiconductor substrate can be easily detected by at least one comparator.

[0035]

As described above, according to the first aspect of the invention, the reference point connected to the internal circuit is connected to the plurality of bonding pads through the plurality of wirings, and the plurality of bonding pads are connected. By detecting the connection state of a plurality of bonding pads and a plurality of bonding wires connected to the leads, with respect to the semiconductor substrate connected to the leads using a plurality of bonding wires,
Since it is detected that each of the plurality of bonding wires is in the connected / disconnected state, it is possible to electrically easily perform disconnection detection in multi-wire bonding, which has been difficult in the past.

According to the second aspect of the invention, the reference point connected to the internal circuit is connected to a plurality of bonding pads through a plurality of wirings, and a plurality of bonding wires are used from the plurality of bonding pads respectively. By detecting the connection state of multiple bonding wires based on the potential difference between multiple bonding pads and the reference point on the semiconductor substrate that is connected to the leads, the multiple bonding wires are in the connected / disconnected state, respectively. Therefore, it is possible to electrically easily detect disconnection in multi-wire bonding, which has been difficult in the past.

According to the third aspect of the present invention, the reference point connected to the internal circuit is connected to a plurality of bonding pads via a plurality of wirings, and a plurality of bonding wires are respectively used from the plurality of bonding pads. By selecting one of the potentials of the plurality of bonding pads with respect to the semiconductor substrate connected to the lead and then detecting the connection state of the bonding wire based on the potential difference between the bonding pad and the reference point, Since it is detected that the bonding wire is in the connected / disconnected state, the number of comparators can be reduced to one, the area of the device can be reduced, and multi-wire bonding which has been difficult in the past The disconnection detection can be easily performed electrically.

[Brief description of the drawings]

FIG. 1 is a diagram showing a semiconductor substrate connection state detection device according to a first embodiment of the present invention.

FIG. 2 is a diagram showing an equivalent circuit of the first exemplary embodiment of the present invention.

FIG. 3 is a MOS used in the first embodiment of the present invention.
It is a figure which shows the internal circuit of a comparator.

FIG. 4 is a diagram showing an operation of the MOS comparator shown in FIG.

5 is an enlarged graph showing an intersection (c) of the input waveform (a) and the output waveform (b) shown in FIG.

FIG. 6 is a diagram showing a semiconductor substrate connection state detection device according to a second embodiment of the present invention.

FIG. 7 is a diagram showing a third embodiment of a semiconductor substrate used in the present invention.

FIG. 8 is a diagram showing a fourth embodiment of a semiconductor substrate used in the present invention.

FIG. 9 is a plan view showing an example of a conventional semiconductor substrate.

FIG. 10 is a plan view showing an example in which a bonding wire is broken on a conventional semiconductor substrate.

FIG. 11 is a cross-sectional view and a plan view of a broken bonding wire portion.

[Explanation of symbols]

 1 Semiconductor Substrate 3 Bonding Pad 5 First Metal Wiring 7 Second Metal Wiring 9 Reference Point 11 Comparator 13 Bonding Wire 15 Lead 17 Internal Circuit 19 Resistance Component of Metal Wiring 3 21 Multiplexer

Claims (3)

[Claims] 1. A semiconductor substrate which is connected to a plurality of bonding pads from a reference point connected to an internal circuit via a plurality of wirings and is connected to a lead from each of the plurality of bonding pads using a plurality of bonding wires. On the other hand, a connection state detection device for a semiconductor substrate that inspects the connection / disconnection state of the plurality of bonding wires, and detects the connection state of the plurality of bonding wires connected to the plurality of bonding pads and the leads. A semiconductor substrate connection state detection device comprising a connection state detection means. 2. The semiconductor substrate according to claim 1, wherein the connection state detecting means detects a connection state of the plurality of bonding wires based on a potential difference between the plurality of bonding pads and the reference point. Connection state detection device. 3. The semiconductor substrate connection state detection device according to claim 2, wherein the connection state detection unit has a selection unit that selects one of the potentials of the plurality of bonding pads.