WO2016117834A1

WO2016117834A1 - A wave guide for chip-to-chip communication and a semiconductor package comprising the same

Info

Publication number: WO2016117834A1
Application number: PCT/KR2015/013807
Authority: WO
Inventors: Chul Soon Park; Inn Yeal Oh; Tae Hwan Jang; Hong Yi Kim; Chae Jun Lee
Original assignee: Korea Advanced Institute of Science and Technology KAIST
Current assignee: Korea Advanced Institute of Science and Technology KAIST
Priority date: 2015-01-23
Filing date: 2015-12-16
Publication date: 2016-07-28
Anticipated expiration: 2017-07-23
Also published as: KR20160091138A; KR101750282B1

Abstract

The present invention discloses a wave guide for chip-to-chip communication and a semiconductor package comprising the same, the waveguide including a first conductor unit, a dielectric strip stacked at an upper surface of the first conductor unit, and a second conductor unit formed at a lateral surface of the dielectric strip and formed with at least one via hole, and the semiconductor package comprising the wave guide for chip-to-chip communication including a PCB (Printed Circuit Board), a first chip positioned on the PCB to perform an RF signal transmission, and a second chip positioned on the PCB to perform an RF signal receipt, wherein the waveguide is interconnected between the first and second chips to perform an RF signal transmission.

Description

A WAVE GUIDE FOR CHIP-TO-CHIP COMMUNICATION AND A SEMICONDUCTOR PACKAGE COMPRISING THE SAME

The teachings in accordance with exemplary and non-limiting embodiments of this invention relate generally to a wave guide for chip-to-chip communication and a semiconductor package comprising the same, and more particularly, to a wave guide for improving communication efficiency between chips and chips on a PCB (Printed Circuit Board) in a chip-to-chip communication system, and a semiconductor package comprising the same.

The core wiring (cabling) technology for future terminals including flexible gadgets lies in high speed chip-to-chip transmission technology. The desktops and notebooks evolving to a high performance computing system will be such that communication speed with peripheral circuits including processors and memories will be greatly speeded up to a level of 100 Gbps (Gigabits/second), and as a result, a super high speed connectivity will be essential in order to minimize a transmission loss between chip/board of these systems.

The currently used FR-4 based digital cabling technology is widely used due to advantages of FR-4 dielectric being reasonable in price and advantageous in mass production. However, the FR-4 dielectric is disadvantageous in that it has a high loss tangent, and insertion loss decreases as frequency increases when transmission line is manufactured using the FR-4 dielectric because the loss tangent has a tendency of increasing quickly as frequency increases.

Particularly, degradation in FR-4 transmission line is further deteriorated when the frequency increases over 100 GHz to thereby create an insertion loss and to reduce a 3-dB bandwidth as well. Furthermore, a repeater must be installed to amplify to a distinguishable voltage level a digital signal that is attenuated to compensate the loss characteristic of the FR-4 dielectric, and power consumption disadvantageously increases in response to transmission distance because the number of repeaters increases as the transmission is lengthened in case of digital lines.

A chip-to-chip communication using optical interconnect has been studied as a best alternative in order to overcome the thus-mentioned limitation in the PCB wiring of high speed digital signal. Although the chip-to-chip communication using an optical interconnect is relatively advantageous in long distance signal transmission due to low loss in an optical waveguide during high speed transmission, disadvantage is that circuits for optical/electronic conversion and electrical/optical conversion, and optical waveguides are additionally required. Furthermore, it is impossible to realize a monolithic integration due to improbability to integrate devices on silicone for optical/electronic conversion and electrical/optical conversion in case of optical interconnect, and manufacturing costs increase due to additional requirement of waveguides.

Meantime, as one of technologies to solve the disadvantages/problems occurring in the prior art, RF communication technology for chip-to-chip high speed transmission has been researched of late. The transmission method through a transmission line by modulating a digital signal on an RF carrier frequency {RF transmission, RF-I (RF-Interconnect)}can advantageously receive/modulate an attenuated signal free from a separate repeater because of high sensitivity, and has a competitiveness over a digital signal transmission method because of no generation of additional power consumption. Furthermore, the RF-I transmission method has another advantage of high energy efficiency over the chip-to-chip communication method using optical interconnect at the time of signal transmission.

Hence, the RF-I transmission method is proposed as an optimal method for high speed connectivity of chip-to-chip and chip-display, and therefore there is a need to improve an RF transmission channel.

Accordingly, the present invention has been made keeping in mind the above disadvantages/problems occurring in the prior art, and an object of the present invention is to provide a wave guide for chip-to-chip communication and a semiconductor package comprising the same, configured to improve data transmission efficiency by reducing an insertion loss on a data transmission line.

Another object is to provide a wave guide for chip-to-chip communication and a semiconductor package comprising the same, configured to increase data transmission efficiency by compensating disadvantages of a conventional transmission line that increases an insertion loss in response to frequency.

In one general aspect of the invention, there is provided a wave guide for chip-to-chip communication, comprising:

a first conductor unit;

a dielectric strip stacked at an upper surface of the first conductor unit; and

a second conductor unit formed at a lateral surface of the dielectric strip and formed with at least one via hole.

Preferably, but not necessarily, the dielectric strip may be so formed as not to protrude more than the second conductor unit.

Preferably, but not necessarily, the via hole may be formed to a direction perpendicular to a length direction of the dielectric strip.

In another general aspect of the present invention, there is provided a semiconductor package comprising a wave guide for chip-to-chip communication, the semiconductor package comprising:

a PCB (Printed Circuit Board);

a first chip positioned on the PCB to perform an RF signal transmission; and

a second chip positioned on the PCB to perform an RF signal receipt, wherein the waveguide is interconnected between the first and second chips to perform an RF signal transmission.

Preferably, but not necessarily, the waveguide may be connected to the first and second chips through an antenna.

Preferably, but not necessarily, the antenna may be a dipole antenna.

Preferably, but not necessarily, the first and second chips may be connected to the dipole antenna via wire-coupled structure.

The wave guide for chip-to-chip communication and the semiconductor package comprising the same according to exemplary embodiments of the present invention have advantageous effects in that data transmission efficiency can be improved by reducing insertion loss on the data transmission line.

Another advantageous effect is that data transmission efficiency can be increased over a conventional transmission line that increases the insertion loss in response to frequency because of having a predetermined insertion loss in response to frequency within a predetermined scope.

FIGS. 1a and 1b are plan and front views of a waveguide according to an exemplary embodiment of the present invention.

FIGS.2a and 2b are schematic views illustrating a soft-surface structure.

FIGS.3a and 3b are schematic views illustrating an off-chip antenna according to an exemplary embodiment of the present invention.

FIGS. 4a and 4b are schematic views illustrating a coupled structure between an antenna and a chip according to an exemplary embodiment of the present invention.

FIGS.5a and 5b are schematic views illustrating a semiconductor package comprising a wave guide for chip-to-chip communication according to an exemplary embodiment of the present invention.

FIGS.6a and 6b are graphs illustrating a reflection loss and an insertion loss according to prior art.

FIGS. 7a and 7b are graphs illustrating reflection loss and insertion loss according to an exemplary embodiment of the present invention.

Hereinafter, exemplary embodiments will be described in detail with reference to the accompanying drawings, wherein the same reference numerals are used to denote the same or substantially the same devices throughout the specification and the drawings. Accordingly, in some embodiments, well-known processes, well-known device structures and well-known techniques are not illustrated in detail to avoid unclear interpretation of the present invention. Throughout the specification, unless explicitly described to the contrary, the terms "-er", "-or", and "module" may be used interchangeably to denote an entity configured to perform the operations described and mean units for processing at least one function and operation and can be implemented by hardware components or software components, and combinations thereof.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

FIG. 1 illustrates a waveguide (100) according to an exemplary embodiment of the present invention, where FIG. 1a is a plan view of a waveguide (100) according to an exemplary embodiment of the present invention, and FIG. 1b is a front view of a waveguide (100) according to an exemplary embodiment of the present invention.

Referring to FIG. 1a, the waveguide (100) may include a dielectric strip (110) and a conductor unit (120). As illustrated in FIG. 1b, the dielectric strips (110) may be stacked on a first conduction unit (120a), and the second conduction unit (120b) may be formed at a lateral surface of the dielectric strip (110). The dielectric strip (110) may be so formed as not to protrude more than the second conductor unit (120b), or may be formed at a same height as that of the second conductor unit (120b).

Although the exemplary embodiment has described that a cross-section of the waveguide has an angular shape, the present invention is not limited thereto, and the cross-section of the waveguide may have a round shape, or other shapes. As illustrated in FIGS. 1a and 1b, the second conduction unit (120b) may be formed with at least one via hole (130).

When it is assumed that radio wave advances to a length direction of dielectric strip (110), the via hole (130) may be formed to a direction perpendicular to the length direction of the dielectric strip. Furthermore, as illustrated in FIG. 1b, the via hole (130) may be so formed as to pass through an upper surface and a bottom surface of the second conduction unit (120b). As discussed in the foregoing, a soft-surface structure may be realized on a PCB by continuously forming at least one via hole (130). The soft-surface structure defines structures as illustrated in FIGS. 2(a) and 2(b), and a height of a dielectric on a soft-surface may be obtained by the following Equation 1.

h=

where,

is an effective dieletric constant.

Furthermore, a coupled radio wave of the soft-surface may be transmitted along the soft-surface, when the height (h) of soft-surface is designed as above. At this time, an insertion loss may be obtained by the following Equation 2.

where,

is an insertion loss per unit length,

is a loss tangent of dielectric, and

is a dielectric constant of dielectric. That is, when a waveguide is realized according to an exemplary embodiment of the present invention, the insertion loss can be reduced because an effective dielectric constant relatively decreases due to fringing radio wave to air is great over the prior art. FIG. 2(b) illustrates a view seen from a front surface of a soft surface structure, where d is a height of rugged conductor constituting a soft surface, v is a width of conductor forming a soft surface, w is a gap between a conductor and a conductor regularly arranged to form a soft surface, t is a vector advanced by radio wave through a soft surface, l is a vector perpendicular to a vector advanced by radio wave through a soft surface, n is a vector perpendicular to a soft surface plane, Si is a start height of a conductor forming a soft surface, and So is an end height of a conductor forming a soft surface.

FIG. 3 illustrates an antenna (200) according to an exemplary embodiment of the present invention. Although the antenna (200) according to the exemplary embodiment of the present invention is an off-chip antenna, i.e., a dipole antenna, the type of antenna is not limited thereto. FIG.3a is a plan view of a dipole antenna (200) and FIG. 3b is a front view of the dipole antenna (200).

The dipole antenna is a resonant antenna characterized by a signal radiated to all directions and functions as a coupler in which a signal is coupled to a waveguide in the exemplary embodiment of the present invention. As illustrated in FIGS. 3a and 3b, the dipole antenna (200) according to the exemplary embodiment of the present invention may include an upper panel (210), an antenna unit (220), and a bottom panel (230), and may further include a feeding unit (211) and an antenna connection unit (221). Hereinafter, a coupled structure between a dipole antenna and a chip will be described with reference to FIG. 4.

FIG. 4a is a plan view of coupled structure between an off-chip antenna (200) and a chip (300), and FIG. 4b is a front view thereof.

Although the exemplary embodiment has described that the chip (300) is a CMOS chip, it is an exemplary description, and the type of chip is not limited thereto. As illustrated in FIGS. 4a and 4b, the chip (300) and the antenna (200) can be connected by connecting a chip connection unit (310) of the chip (300) and an upper panel (210) of the antenna (200) by a wire bonding structure (400). At this time, one or more the wire bonding structures (400) may be formed, and may be formed for connection between the chip connection unit (310) and an antenna connection unit (221) and between the chip connection unit (310) and the feeding unit (211).

Next, a semiconductor package (500) including a waveguide (100) according to an exemplary embodiment of the present invention will be described with reference to FIGS. 5a and 5b.

Referring to FIG. 5a, the chip (300) and an off-chip antenna (200) connected by the wire bonding structure (400) may be connected to an upper surface of a wave guide (100). At this time, if a chip (300a) is a chip configured to perform a wireless RF transmission, a chip (300b) may be a chip configured to perform reception of the wireless RF signal, and vice versa. When the chip (300a) transmits a wireless RF signal, the signal may be transmitted to an off-chip antenna (200a) through the wire bonding structure (400), and the signal transmitted to the off-chip antenna (200a) may be transmitted to a chip (300b) through an opposite off-chip antenna (200b) by being coupled to the waveguide (100).

FIG. 6 is a loss graph according to prior art, where FIG.6a illustrates a reflection loss while FIG. 6b illustrates an insertion loss. FIG. 7 is a loss graph according to an exemplary embodiment of the present invention, where FIG. 7a illustrates a reflection loss while FIG.7b illustrates an insertion loss.

As ascertained by FIGS. 6 and 7, an insertion loss of the present invention is lower than that of prior art. Furthermore, it can be noted that the present invention is further advantageous in the aspect of insertion loss, in consideration of additional coupling of accessory elements essentially required for realizing the prior art in real terms.

While the present invention has been described with respect to the above exemplary embodiments, the present invention is not so limited and should be understood to be merely exemplary. Various modifications to the invention will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other variations without departing from the spirit or scope of the invention. For example, each constituent element explained in detail in the above exemplary embodiments may be implemented in other various modifications.

Claims

A wave guide for chip-to-chip communication, comprising:

a first conductor unit;

a dielectric strip stacked at an upper surface of the first conductor unit; and

a second conductor unit formed at a lateral surface of the dielectric strip and formed with at least one via hole.
The waveguide of claim 1, wherein the dielectric strip is so formed as not to protrude more than the second conductor unit.
The waveguide of claim 1, wherein the via hole is formed to a direction perpendicular to a length direction of the dielectric strip.
A semiconductor package comprising the wave guide for chip-to-chip communication of any one claim of 1 to 3, the semiconductor package comprising:

a PCB (Printed Circuit Board);

a first chip positioned on the PCB to perform an RF signal transmission; and

a second chip positioned on the PCB to perform an RF signal receipt, wherein the waveguide is interconnected between the first and second chips to perform an RF signal transmission.
The semiconductor package of claim 4, wherein the waveguide is connected to the first and second chips through an antenna.
The semiconductor package of claim 5, wherein the antenna is a dipole antenna.
The semiconductor package of claim 6, wherein the first and second chips are connected to the dipole antenna via wire-coupled structure.