US 6,587,320 B1 · Apparatus for current ballasting ESD sensitive devices

Abstract

A current ballasting circuit for an ESD protection device couples nonintersecting conductive strips between a common contact pad and the contact electrodes of the ESD protection device. The connecting strips form respective electrically isolated ballasting resistors between the external contact pad and the contact electrodes of the ESD device. In addition, lateral resistances are formed between the contact strips which enhance the operation of the multiple ballasting resistors. The conductive strips may be made from metal, polysilicon or by a vertically meandering series connection of polysilicon layers, metal layers and interconnecting vias. The lateral resistance between the parallel conductive paths may be enhanced by segmenting both the drain and source electrodes. In one example, the gate electrode of an MOS ESD device extends locally between each pair of strips to segment the drain and source regions. The lateral resistance between the conductive strips is further enhanced by defining an additional gate electrode, having a portion that is parallel to the gate electrode of the ESD device and further portions that extend between the conductive strips. Multiple ESD devices may be connected in parallel to provide additional paths for shunting ESD current.

Claims18

Dependent claims

Apparatus for current ballasting an electrostatic discharge (ESD) sensitive device having a first region and a second region, for protecting a node in an electronic circuit from over voltage conditions by providing a conductive path through the first and second regions to a terminal configured to be coupled to a source of reference potential when said ESD device is turned on, said apparatus comprising:

a plurality of spaced connecting terminals in the first region of the ESD sensitive device for providing respective electrical contacts to the first region, the first region and the spaced connecting terminals being configured to exhibit a lateral resistance in the first region between successive ones of the spaced connecting terminals, wherein the lateral resistance is greater than a resistance of the conductive path when the ESD device is turned on;
and
a plurality of isolated nonintersecting conductive strips, each having a first end and a second end, the first end of each of the isolated nonintersecting conductive strips being electrically coupled to the node and the second end of each of the isolated nonintersecting conductive strips being coupled to a respectively different one of the plurality of spaced connecting terminals.

An electrostatic discharge (ESD) protection device for protecting a node in an electronic circuit from over voltage conditions by providing a conductive path through the ESD device to a terminal configured to be coupled to a source of reference potential when said ESD device is turned on, the ESD device comprising:

a drain region of a first semiconductor type, the drain region including a plurality of spaced connecting terminals which provide respective electrical contacts to the drain region, wherein the drain region and the spaced connecting terminals are configured to exhibit a lateral resistance between successive ones of the spaced connecting terminals, which lateral resistance is greater than a resistance of the conductive path through the ESD device when the ESD device is turned on;
a channel region of a second semiconductor type, having a length and a width, the channel region being in physical contact with the drain region along the width of the channel region;
a source region of the first semiconductor type, the source region being in physical contact with the channel region along the width of the channel region and separated from the drain region by the length of the channel region, the source region being connected to the terminal which is configured to be connected to a source of reference potential;
a gate electrode, insulated from and positioned above the channel region;
a plurality of isolated nonintersecting conductive strips, each having a first end and a second end, the first end of each of the isolated nonintersecting conductive strips being electrically coupled to the node and the second end of each of the nonintersecting conductive strips being coupled to a respectively different one of the plurality of spaced connecting terminals.

2 more elements

A composite electrostatic discharge (ESD) protection device for protecting a node in an electronic circuit from over voltage conditions by providing a conductive path through the ESD device to a reference terminal configured to be coupled to a source of reference potential when said ESD device is turned on, the ESD device comprising:

a plurality of component ESD devices, each component ESD device including:
a drain region of a first semiconductor type, the drain region including a plurality of spaced connecting terminals which provide respective electrical contacts to the drain region, wherein the drain region and the spaced connecting terminals are configured to exhibit a lateral resistance between successive ones of the spaced connecting terminals, the lateral resistance being greater than a resistance exhibited by the conductive path when the composite ESD device is turned on;
a channel region of a second semiconductor type, having a length and a width, the channel region being in physical contact with the drain region along the width of the channel region;
a source region of the first semiconductor type, the source region being in physical contact with the channel region along the width of the channel region and separated from the drain region by the length of the channel region, the source region including a plurality of further spaced connecting terminals which provide respective electrical contacts to the source region, wherein the source region and the further spaced connecting terminals are configured to exhibit a lateral resistance between successive ones of the further spaced connecting terminals;
a gate electrode, insulated from and positioned above the channel region;
first and second common electrically conductive terminals;
a plurality of first nonintersecting conductive strips, each having a first end and a second end, the first end of each of the first nonintersecting conductive strips being electrically coupled to the first common electrically conductive terminal and the second end of each of the first nonintersecting conductive strips being coupled to a respectively different one of the plurality of spaced connecting terminals for making electrical contact with the drain region;
a plurality of second nonintersecting conductive strips, each having a first end and a second end, the first end of each of the second nonintersecting conductive strips being electrically coupled to the second common electrically conductive terminal and the second end of each of the second nonintersecting conductive strips being coupled to a respectively different one of the plurality of further spaced connecting terminals for making contact with the source region;
and
a first conductor connecting the first common electrically conductive terminals of all of the component ESD devices;
a second conductor connecting the second common electrically conductive terminals of all of the component ESD devices to the reference terminal.

8 more elements

An electrostatic discharge (ESD) protection device comprising:

a plurality of component ESD devices, each component ESD device including:
a first region of a first semiconductor type, the first region including a plurality of spaced connecting terminals which provide respective electrical contacts to the first region, wherein the first region and the spaced connecting terminals are configured to exhibit a lateral resistance between successive ones of the spaced connecting terminals;
a second region of a second semiconductor type, the second region including a plurality of further spaced connecting terminals which provide respective electrical contacts to the second region, wherein the second region and the further spaced connecting terminals are configured to exhibit a lateral resistance between successive ones of the further spaced connecting terminals;
first and second common electrically conductive terminals;
a plurality of first nonintersecting conductive strips, each having a first end and a second end, the first end of each of the first nonintersecting conductive strips being electrically coupled to the first common electrically conductive terminal and the second end of each of the first nonintersecting conductive strips being coupled to a respectively different one of the plurality of spaced connecting terminals for making electrical contact with the first region;
a plurality of second nonintersecting conductive strips, each having a first end and a second end, the first end of each of the second nonintersecting conductive strips being electrically coupled to the second common electrically conductive terminal and the second end of each of the second nonintersecting conductive strips being coupled to a respectively different one of the plurality of further spaced connecting terminals for making contact with the second region;
and
a first conductor connecting the first common electrically conductive terminals of all of the component ESD devices;
a second conductor connecting the second common electrically conductive terminals of all of the component ESD devices.

6 more elements

Dependencies are inferred from the claim text.

Apparatus for current ballasting ESD sensitive devices

Life of this patent

Apparatus for current ballasting ESD sensitive devices

Life of this patent

Abstract

Claims18