JPH09121449A - Static discharge protection using variable-length terminal device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve the potential equilibrium between a plug-in and a host equipment without destructing thin insulator, etc., by connecting a first terminal to a constituent of a first length and a lower sensitivity and connecting a second terminal to a constituent element of a second length and a higher sensitivity and making the first length longer than the second one. SOLUTION: An integrated circuit 106 is inserted into a limited cavity 104 of a main body 102 of an insulator and a terminal 110 is assigned to the ground potential of the integrated circuit 106 and power is supplied to a chip from a terminal 112 and then the output of the chip is connected to one or more terminals 114 and an input signal is supplied to the chip from a terminal 116. To the terminal 116, a constituent element of a lower sensitivity is connected and the length of the element is set to a first one. To the terminal 110, a constituent element of a higher sensitivity is connected and the length of the element is set to a second one. The first length is longer than the second one. By this method, the potential equilibrium can be achieved between a plug-in and a host equipment without destructing a thin insulator and a conductor passage.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD OF THE INVENTION This application has a common inventor and assignee, and is incorporated herein by reference, entitled "Electrostatic Discharge Protection Using Resistive Terminal Elements," September 20, 1995.
It is related to other U.S. patent application Ser. No. 08 / 530,968 filed in Japanese.

The present invention relates to electrostatic discharge protection of electronic circuits, and more particularly to circuits formed of semiconductor chips having insulators and wire conductors that are susceptible to damage from the rapid discharge of stored energy.

[0003]

BACKGROUND OF THE INVENTION The increased speed and functionality of integrated circuit technology has been achieved with denser circuit packing and thinner conductor linewidths. Also, lateral dimension scaling of integrated circuit features also requires a thinner insulating layer, which is typically thermally grown silicon oxide on a silicon substrate. A useful circuit is 7
It is manufactured with a gate oxide layer that is 5 angstroms thick. These oxides have lower defect densities than the thicker ones, and therefore withstand higher electric fields before breakdown, but nevertheless thin oxide films are inadvertently caused by electrostatic discharge (ESD). More susceptible to dielectric breakdown. Further advances in storage technology provide read-only memory (ROM) with a capacity of 20 megabytes on a chip of about 1 square inch. This memory has approximately 2.5 × 1.
It is packaged in a low cost, robust container measuring 125 x 0.25 inches. The spread of this technology to the large consumer market is
There is an increasing need to protect sensitive circuits from ESD.

One of the energy sources that destroys thin wire conductors and thin gate oxides of devices such as memory is electrostatic energy stored in an insulated human body. The human body may be charged to a potential of 200 volts with respect to ground, and the human body has a capacity of 10 picofarads (pf) to 10
It is well known to span the 0 pf range. When the electric charge charged in the human body is applied to the input gate terminal of the semiconductor chip, which is grounded, the applied voltage is sufficient to initiate the destruction of the thin insulating layer, and this rapid discharge of energy causes It may be sufficient to permanently damage the insulation and vaporize the wire conductor.

Many metal oxide silicon (MOS) devices are equipped with shunt diodes and resistors that can withstand. While this works well in protected environments such as computers, it is not very reliable in the large market where memory chips with music stored are repeatedly plugged into portable players. Also, the protection circuit requires space on the chip and may degrade high speed performance.

When a memory chip is plugged into the host device, there are several cases regarding ESD. First, there is a case where the host device is connected to the ground potential and the operator who handles the chip is charged. Second, there is a case where the device is insulated from ground and charged, and the operator inserting the memory is charged as well. Third,
In this case, the device is charged but the human body is not.

Therefore, in all of these cases, there is a need for electrostatic protection that ensures reliable operation of the memory chip as well as the host device. The purpose is
The goal is to achieve potential equilibrium between the plug-in and the host device without breaking thin insulators or conductor paths that can be as narrow as 0.5 microns wide.

[0008]

SUMMARY OF THE INVENTION The present invention is directed to an apparatus and method for protecting an integrated circuit from damage caused by electrostatic discharge, in which either a plug or socket connecting the integrated circuit to another device is provided. It has variable length terminals to connect the various terminals of the integrated circuit and can withstand discharge of electrostatic energy.

In one embodiment of the present invention, the terminals are of two lengths, the longer terminals leading to areas of the electronic circuit that can better withstand the discharge of electrostatic energy. This area of the circuit is the ground path. The other terminal has a shorter length and interconnects the power supply, the output signal path and the input signal path.

In another embodiment of the invention, the number of terminal lengths can be increased to three or four and the connection to the circuit to be protected is E when the plug is inserted into the socket.
The circuit elements whose sensitivity to SD is gradually increased are arranged so as to be sequentially matched with the corresponding external terminals. In an arrangement with three lengths, the ground terminal is the longest to ensure that the ground connection is made first. The ground circuit path typically has the thickest insulator and largest linewidth in an integrated circuit. The power supply terminal has the next longest terminal length, and the signal terminal is the shortest. As an alternative, the power and output signal terminals are typically of intermediate length, leaving the shortest length for input signals leading to the area of the integrated circuit that typically has the thickest insulator and narrowest conductor linewidth. Can be used to group together.

In an arrangement with four lengths, the terminal length is reduced from ground to power supply, output signal, input signal in that order.
The variable length terminals can be on either the plug side or the socket side of the connection, or both.

The method of practicing the present invention provides a plug or socket with variable length terminals arranged such that the terminals leading to the more and more vulnerable areas of the circuit will be connected later in the process of mating the connector pairs. Accompanied by. This method can use two, three or four different lengths, where the ground terminal is the longest and the input terminal is the shortest. The power and ground terminals are of intermediate length.

An advantage of the present invention is that it does not require additional components to provide different levels of protection to integrated circuits that become increasingly sensitive to ESD as packing density and speed increase.

These and other features and advantages of the present invention will be better understood upon consideration of the following detailed description of the preferred embodiment taken in conjunction with the accompanying drawings.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Referring to FIG. 1, there is shown a device 100 which is a plug-in module containing electronic circuitry such as an integrated circuit which may be a processor or memory circuit. The insulating body 102 defines a cavity 104 that houses the integrated circuit 106. The wire joint 120 is
It is one of the means for connecting the bond pads of an integrated circuit to a series of external terminals. There are also other interconnection means, such as those using the ridge technique, in which the active side of the chip is diced and the solder on the ridge is reflowed to make the last leading connection to the same external terminal. Ground potential is terminal 110
The power of the chip is supplied from the terminal 112, the output from the chip is connected to the one or more terminals 114, and the input signal to the chip is supplied from the one or more terminals 116. All of these terminals are stepped parts 1 through which the terminals penetrate.
Their lower surface is supported by an insulating body which also defines 08. The exposed upper surface of each terminal serves to contact the terminal with a flat-ended socket (not shown).

However, the terminals of this plug-in are
The exposed length has changed when measured from the step 108. The terminal 110 for supplying the ground potential is the longest, the terminal 112 for supplying the power to the chip is the second longest, the terminal 114 for transmitting the output from the chip is the next length, and finally, the input is supplied to the chip. The terminal 116 is the shortest of all terminals. The selected length is inversely related to the susceptibility of the various functional areas of the chip to ESD. For example, when the plug-in is plugged into the socket of the host device, all its terminals terminate in a row or plane, with terminal 110 (ground potential) being the first terminal to contact. The electrostatic charge stored in either the plug-in or the socket in the instrument housing is best dissipated by first making a ground potential connection. This is because chips are usually designed to have thicker and larger areas of insulation for power and ground circuits than for signal circuits. The terminal 112 (power supply) becomes the next terminal that contacts the corresponding power supply terminal of the socket. The output terminal 114 becomes the next contact terminal,
Finally, the input terminal is the last terminal to make contact with the corresponding terminal of the socket. This is because the chip's input is most sensitive to ESD due to the thin gate insulator and finally the thin conductor leading to the input.

The method of connecting the conducting terminals of an integrated circuit in the order in which they are arranged by the relative ability of their circuit paths to dissipate charge, starting with a ground connection and ending with an input terminal is a method for integrated circuits, especially in large markets. Provides different levels of protection to devices, which are intended to be repeatedly plugged into equipment.

Referring now to FIG. 2, another embodiment of the present invention having an insulating body 202 having a rim 208 through which a series of unsupported pin-type terminals having exposed variable lengths extends. Device 200 is shown. Similar to FIG. 1, the longest of these, terminal 210, is
It provides a ground potential connection to an integrated circuit (not shown) contained in the insulating body. The next longest is terminal 212, which powers the integrated circuit. One or more terminals 214 carry the output from the integrated circuit but have the following lengths. And finally, one or more terminals 216 are connected to the inputs of the integrated circuit and are the shortest of all. This principle is the same as in the device of FIG. 1 and the order of contact with the corresponding terminals of the socket by plugging is in the same order as the ability of the circuit to be protected to dissipate electrostatic charges.

Next, referring to FIG. 3, a step 308 and
Shown is an insulating body 302 with exposed terminals 310-316 having the same chip connections as terminals 110-116 of FIG. 1, respectively. The plug-in terminals of this embodiment of the present invention have the same exposed length. Socket 3
40 has a reference surface 388 through which a series of terminals 350-356 pass. The longest terminal 350 provides a ground connection with the corresponding terminal 310 of the plug-in. The next longest terminal 352 supplies power to the corresponding terminal 312. The next longest terminal 354 receives the output signal from the corresponding terminal 314. The shortest terminal 356 then supplies the input signal to terminal 316. The point is that ESD protection,
Here, a terminal having a variable length that ensures that the connection sequence proceeds from the terminal with the lowest sensitivity to ESD damage to the terminal with the highest sensitivity to ESD damage is a terminal whose opposing body ends in a row or plane. Can be implemented on one side of the plug / socket connection. The advantage of the embodiment of FIG. 3 is that plug-ins with bodies 302 from various manufacturers can all have a common terminal of length L, while the device side has terminals of variable length L _{1 to} L _4. It is to provide ESD protection in the socket.

In the preferred embodiment of FIG. 3, the insertion is 0.
Achieved in 3 seconds so that most of the energy dissipates through the ground terminal in 0.003 seconds before the input terminals make contact. The human body has a maximum capacity of 100 pf and 10 k
It has a resistance of ohms, and therefore the well-known exponential decay time constant of the current and potential associated with the discharge of the capacitor through the resistor is T = RC, in seconds, ie, in this case electrostatic charge between them. 63% of 1 or (1- (1
/ E) has a dissipation of 1 microsecond. When time equals 3 time constants, 95% of the charge dissipates.

Modifications and variations of the embodiment described in detail are:
It can be done without departing from the scope of the invention. In particular, the relative position of the terminals with respect to each other can be varied, for example the power and ground connections can be external terminals with the signal carrying terminals sandwiched between them.
The terminals need not be arranged in a flat array, but they may be arranged in a circle or a three-dimensional array. The exact length of each type of terminal can vary, but the important point is that the terminal with the least sensitivity to ESD is connected first and the E
The terminal most sensitive to SD damage is connected last. 2 if ground and power are connected to the long terminal that can be connected first and all other signals are through the short terminal that is subsequently connected
Only one length is needed. Alternatively, the power and output terminals
When the terminal has an intermediate length as compared with the ground (long) terminal and the input (short) terminal, the terminal length may be three. Using the same methodology, there are other obvious combinations between two and three length configurations.

[Brief description of the drawings]

FIG. 1 shows a plan and side sectional view of one embodiment of the present invention.

FIG. 2 shows a plan view of another embodiment of the present invention.

FIG. 3 shows a plan view of still another embodiment of the present invention.

Claims (16)

[Claims] 1. An apparatus for protecting an electronic circuit having components that are more sensitive to electrostatic discharge and components that are less sensitive to electrostatic discharge, the device having a first length. A first terminal connected to the less sensitive component, and a second terminal having a second length and connected to the more sensitive component, The length of 1 is greater than the length of the second. 2. The apparatus according to claim 1, further comprising:
An apparatus including a third terminal having a third length that is intermediate between the first length and the second length. 3. The apparatus according to claim 2, further comprising:
An apparatus comprising a fourth terminal having a fourth length intermediate between the first and third lengths. 4. An apparatus for protecting an electronic circuit having a ground, a power supply, an output and an input component from electrostatic discharge, the ground terminal having a first length and a power supply terminal having a second length. And at least one output terminal having a third length and at least one input terminal having a fourth length, each of the second, third and fourth lengths preceding it. A device that is continuously shorter than that, whereby contact is made sequentially between the terminals and corresponding mating terminals that terminate in a plane. 5. A housing for electrostatic protection of an integrated circuit memory, the housing adapted to be plugged into a socket having a plurality of terminals terminating in a plane, the integrated circuit memory being supported by the housing. A group of terminals connected to the ground, providing a power supply and at least one output connection, each terminal having a set of terminals having a first exposed length; A housing having at least one input terminal having a second exposed length that is less than the exposed length. 6. A housing for electrostatic protection of an integrated circuit memory, the housing adapted to be plugged into a socket having a plurality of terminals terminating in a plane, the ground terminal having a first length. A power supply terminal having a second length, at least one output terminal having a second length, and at least one input terminal having a third length, the second and third lengths Each of the housings is continuously shorter than its predecessor length, thereby providing a sequential contact between the terminals and corresponding mating terminals of the socket. 7. A housing for electrostatic protection of an integrated circuit memory, the housing adapted to be plugged into a socket having a plurality of terminals terminating in a plane, the ground terminal having a first length. A power supply terminal having a second length, at least one output terminal having a third length, and at least one input terminal having a fourth length, the second, third, and A housing, each of which has a length which is successively shorter than the length preceding it, whereby a sequential contact is made between said terminals and the corresponding mating terminals of said socket. 8. A socket for electrostatic protection of an integrated circuit, the socket having a plurality of terminals terminating in a plane, the socket adapted to accommodate a plurality of terminals from the integrated circuit, the socket supporting the socket. A first terminal connected to the device for supplying a ground potential, a second terminal connected to the device for supplying power to the integrated circuit, and a signal from the output of the integrated circuit A set of terminals, each terminal having a first exposed length, and a set of terminals adapted to provide an input signal to the integrated circuit. And at least one terminal having a second exposed length that is less than the first exposed length. 9. A socket for electrostatic protection of an integrated circuit, the socket adapted to accommodate a plurality of terminals from said integrated circuit, the socket having a plurality of terminals terminating in a plane, the socket having a first length. A first terminal connected to the device for supplying a ground potential, and a second terminal having a second length and connected to the device for supplying power to the integrated circuit. A terminal, a second length, at least one terminal adapted to receive a signal from the output of the integrated circuit, and a third length, providing an input signal to the integrated circuit. At least one terminal connected to the device for each of said second and third lengths being continuously shorter than the length preceding it, whereby said terminal and said circuit Sequential contact is made between correspondingly matched terminals. Socket. 10. A socket for electrostatic protection of an integrated circuit, the socket having a plurality of terminals terminating in a plane, the socket adapted to accommodate a plurality of terminals from the integrated circuit, a first length. A first terminal connected to the device for supplying a ground potential, and a second terminal having a second length and connected to the device for supplying power to the integrated circuit. A terminal, having a third length, adapted to receive a signal from the output of the integrated circuit, and having a fourth length, supplying an input signal to the integrated circuit. At least one terminal connected to the device for each of said second, third and fourth lengths being successively shorter than the length preceding it, whereby said terminal and said Sequential contact between corresponding mated terminals from the circuit Socket rope. 11. A method of protecting an electronic circuit having a ground, a power supply, an output and an input terminal, the method comprising: connecting the ground terminal to an external ground potential supply source; and connecting the power supply terminal to an external power supply. And the step of connecting the output terminal to an external receiver, the input terminal being connected last. 12. A method of protecting an electronic circuit having a ground, a power supply, an output and an input terminal, the method comprising: connecting the ground terminal to an external ground potential supply source; and connecting the power supply terminal to an external power supply. And the step of connecting the output terminal to an external receptor, and the step of connecting the input terminal to an external signal source, the ground terminal is connected first, the input terminal is the last How to be connected to. 13. A method for protecting an electronic circuit having a ground, a power supply, an output and an input terminal, the method comprising: connecting the ground terminal to an external ground potential supply source; and connecting the power supply terminal to an external power supply. And a step of connecting the output terminal to an external receptor, and a step of connecting the input terminal to an external signal source, the ground terminal is first connected, and the power supply terminal is second. Connected, and the output and input terminals are connected last. 14. A method of protecting an electronic circuit having a ground, a power supply, an output and an input terminal, the method comprising: connecting the ground terminal to an external ground potential supply source; and connecting the power supply terminal to an external power supply. And the step of connecting the output terminal to an external receptor, and connecting the input terminal to an external signal source, the order in which the connection is performed is as described above. 15. A method of protecting a pluggable integrated circuit memory having a ground, a power supply, an output signal and an input signal terminal from electrostatic discharge, the method being combined with the ground, the power supply, the output signal and the input signal terminal. Comprising the steps of preparing a socket having terminals adapted to, the socket terminals varying in length, so that as the integrated circuit is plugged into the socket, each ground,
A method in which a power supply, an output signal, and an input signal terminal are sequentially connected. 16. A method of protecting a pluggable integrated circuit memory having ground, power, output signal and input signal terminals from electrostatic discharge, which is combined with socket ground, power, output signal and input signal terminals. The step of providing a plug having terminals adapted to such that the socket terminals have a constant length and the terminals of the plug have varying lengths, so that as the integrated circuit is plugged into the socket , A method of sequentially connecting each ground, power supply, output signal and input signal terminal.