RF INTEGRATED CIRCUIT WITH ESD PROTECTION AND ESD PROTECTION APPARATUS THEREOF

Abstract

A radio frequency (RF) integrated circuit with electrostatic discharge (ESD) protection and an ESD protection apparatus thereof are provided. The ESD protection apparatus includes a substrate, an RF bonding pad, and an ESD protection unit. The RF bonding pad for transmitting RF signal is disposed upon the substrate. The ESD protection unit is disposed under the RF bonding pad. Wherein, The ESD protection unit includes an inductor electrically connected between the RF bonding pad and the power rail.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are included to provide a further understanding of the invention, and are incorporated in and constitute a part of this specification. The drawings illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.

FIG. 1 is a diagram of a conventional electrostatic discharge (ESD) protection apparatus within the integrated circuit.

FIG. 2 is a diagram of a conventional EDS protection apparatus with an inductor.

FIG. 3 is a block diagram of an RF integrated circuit with ESD protection according to the embodiment of the present invention.

FIG. 4 is a cross-sectional diagram of the RF bonding pad 310 and the ESD protection unit thereof in the RF integrated circuit 300 in FIG. 3 according to the embodiment of the present invention.

FIG. 5 is a platform view of the inductor in spiral arrangement in the ESD protection unit 330 according to the embodiment of the present invention.

FIG. 6 is a perspective view of the inductor in stack arrangement in the ESD protection unit 330 according to the embodiment of the present invention.

DESCRIPTION OF EMBODIMENTS

FIG. 3 is a block diagram of an RF integrated circuit with ESD protection according to the embodiment of the present invention. Please referring to FIG. 3, in the RF integrated circuit 300, an internal circuit 320 receives/emits an RF signal and a common signal respectively through an RF bonding pad 310 and a common bonding pad 350. The power for the internal circuit 320 is provided from outside through a power rail VDD, a power bonding pad 360, a power rail VSS, and a power bonding pad 370. In the embodiment, the power rail VDD is a system voltage rail, and the power rail VSS is a ground rail. In the normal operation, the power rails VSS and VDD are suitable to respectively provide a ground voltage and a system voltage to the internal circuit 120. It needs to be noted that FIG. 3 is a simplified embodiment, and the quantity of actual various pads is not limited by the number shown in FIG. 3.

Usually, a group of ESD protection circuits (for example, ESD protection circuits 340) is disposed between each common bonding pad (for example, a common bonding pad 350) and the internal circuit 320. The ESD protection circuit 340 includes diodes D31, D32, and a resistance R31. The diode D31 is electrically connected between the power rail VDD and the common bonding pad 350 in reverse-biased configuration, and the diode D32 is also electrically connected between the power rail VSS and the common bonding pad 350 in reverse-biased configuration. The resistance R11 is electrically connected between the internal circuit 320 and the common bonding pad 350.

When the common bonding pad 350 produces a positive pulse current resulting from the electrostatic discharge, the resistor R31 can prevent most of the positive pulse current from flowing into the internal circuit 320, and at the same time, the diode D31 can guide most of the positive pulse current to the power rail VDD. Similarly, when the common bonding pad 350 produces a negative pulse current resulting from the electrostatic discharge, the resistor R31 can prevent most of the negative pulse current from flowing into the internal circuit 320, and at the same time, the diode D32 can guide most of the negative pulse current to the power rail VSS.

According to the embodiment, the RF bonding pad 310 is directly connected with the internal circuit 320. The ESD protection unit 330, disposed under the RF bonding pad 310, is directly connected with the RF bonding pad 310. Those skilled in the art can implement the ESD protection unit 330 by any means. According to the embodiment, the ESD protection unit 330 includes an inductor L31. The inductor L31 is electrically connected between the RF bonding pad 310 and the power rail VSS.

As the impulse period of the electrostatic discharge is far longer than the RF signal, for the RF signal in the normal operation, the inductor L31 provides very high resistance. That is, in normal operation, the inductor L31 is served as an open circuit, so that the weak RF signal can be transmitted directly between the RF bonding pad 310 and the internal circuit 320. When an electrostatic discharge occurs in the RF bonding pad 310, the impulse current resulting from the electrostatic discharge may be guided to the power rail VSS by the inductor L31. At this time, if the power bonding pad 370 is connected to the ground, the electrostatic current may flow out of the RF circuit 300 through the power bonding pad 370. When an electrostatic discharge occurs in the RF bonding pad 310, if the common bonding pad 350 is connected to the ground, the electrostatic current may flow out of the RF integrated circuit 300 from the common bonding pad 350 through the inductor L31, the power rail VSS, and the diode D32. Moreover, when an electrostatic discharge occurs in the RF bonding pad 310, if the power bonding pad 360 is connected to the ground, the electrostatic current may flow out of the RF integrated circuit 300 from the power bonding pad 360 through the inductor L31, the power rail VSS, the diode D32, the diode D31, and the power rail VDD.

FIG. 4 is a cross-sectional diagram of the RF bonding pad 310 and the ESD protection unit thereof in the RF integrated circuit 300 in FIG. 3 according to the embodiment of the present invention. The ESD protection unit in FIG. 4 includes a substrate 410, the RF bonding pad 310 and the ESD protection unit 330. In order to precisely describe the relationship among the components, the arrangement of the internal connections is not shown in FIG. 4. Referring to FIG. 3 and FIG. 4, the like reference numerals indicate identical or functionally similar elements. The power rail VSS is disposed upon the substrate 410. The RF bonding pad 310 is also disposed upon the substrate 410, suitable for transmitting the RF signal to the internal circuit 320. The RF bonding pad 310 is disposed upon the uppermost metal layer of the integrated circuit. Of course, the RF bonding pad 310 can also be disposed upon the second or third uppermost metal layer. The internal circuit 320 is disposed in the substrate 410. The internal circuit 320 is electrically connected with the RF bonding pad 310 so as to transit the RF bonding pad 310 to receive/emit RF signal from/to outside. The ESD protection unit 330 is disposed under the RF bonding pad 310. Wherein, the ESD protection unit 330 can be implemented as shown in FIG. 3, and other devices (for example, diodes) may also be included to implement the ESD protection unit 330. All of the various changes of the implementation belong to the scope of the present invention. The ESD protection unit 330 is electrically connected between the RF bonding pad 310 and the power rail VSS.

In the abovementioned embodiment, the inductor L31 can be implemented between the RF bonding pad 310 and the substrate 410 by any means. For example, the inductor L31 can be disposed between the RF bonding pad 310 and the substrate 410 in stack or in spiral arrangement. FIG. 5 is a platform view of the inductor in spiral arrangement in the ESD protection unit 330 according to the embodiment of the present invention. Referring to FIG. 5, in the embodiment, the ESD protection unit 330 includes an inductor L51. The inductor L51 is disposed between the RF bonding pad 310 and the substrate in spiral arrangement. In general, the size of the RF bonding pad 310 is about 75 um*84 um, while the size of the spiral inductor L51 for ESD protection is about 100 um*100 um. As the spiral inductor L51 is disposed under the RF bonding pad 310, the chip area can be saved substantially, and the fabrication cost is reduced.

FIG. 6 is a perspective view of the inductor in stack arrangement in the ESD protection unit 330 according to the embodiment of the present invention. Referring to FIG. 6, in the embodiment, the ESD protection unit 330 includes an inductor L61. The inductor L61 is disposed between the RF bonding pad 310 and the substrate in stack arrangement. In general, the size of the stack inductor L51 for ESD protection is about 50 um*50 um, which is less than the size of the RF bonding pad 310 (about 75 um*84 um). As the stack inductor L51 is disposed under the RF bonding pad 310, the chip area can be saved substantially, and further reduce the fabrication cost.

In summary, according to the present invention, the ESD protection unit is disposed under the RF bonding pad, so that the chip area can be saved substantially, and further reduce the fabrication cost. In addition, as the ESD protection unit includes an inductor electrically connected between the RF bonding pad and the power rail, the internal circuit for receiving/emitting RF signal can be protected from damage due to the electrostatic discharge, and at the same time, the normal RF signal transmission is not impacted.

It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.

Claims

1. An electrostatic discharge (ESD) protection apparatus, comprising: a substrate;an radio frequency (RF) bonding pad, disposed upon the substrate, suitable for transmitting RF signal; andan ESD protection unit, disposed under the RF bonding pad, wherein the ESD protection unit comprises an inductor electrically connected between the RF bonding pad and a power rail.

2. The ESD protection apparatus as claimed in claim 1, wherein the inductor is disposed in stack layout between the RF bonding pad and the substrate.

3. The ESD protection apparatus as claimed in claim 1, wherein the inductor is disposed in spiral layout between the RF bonding pad and the substrate.

4. The ESD protection apparatus as claimed in claim 1, wherein the power rail is a grounded rail.

5. An radio frequency (RF) integrated circuit with electrostatic discharge (ESD) protection, comprising: a substrate;a power rail, disposed upon the substrate;an RF bonding pad, disposed upon the substrate and suitable for transmitting RF signal;an internal circuit, disposed in the substrate and electrically connected with the RF bonding pad, so as to receive/emit RF signal from/to outside via the RF bonding pad; andan ESD protection unit, disposed under the RF bonding pad, wherein the ESD protection unit comprises an inductor electrically connected between the RF bonding pad and the power rail.

6. The RF integrated circuit with ESD protection as claimed in claim 5, wherein the inductor is disposed in stack layout between the RF bonding pad and the substrate.

7. The RF integrated circuit with ESD protection as claimed in claim 5, wherein the inductor is disposed in spiral layout between the RF bonding pad and the substrate.

8. The RF integrated circuit with ESD protection as claimed in claim 5, wherein the power rail is a grounded rail.