KR100660652B1 - Mmic electromagnetic noise filter and microwave integrated circuit device incluing the same - Google Patents

Abstract

An MMIC(Monolithic Microwave Integrated Circuit) type electromagnetic noise filter structure and an RF IC device with the same are provided to minimize the volume and complexity of circuitry and to improve a noise removing efficiency by manufacturing nonlinear semiconductor elements and a noise filter as one piece. A dielectric thin film(42) is formed on an upper surface of a semiconductor substrate(41). A coplanar signal line(43) is formed on the dielectric thin film. Both end portions of the coplanar signal line are connected with input/output portions. First and second coplanar ground lines(44a,44b) are formed at both sides of the coplanar signal line on the dielectric thin film.

Description

MIC type electromagnetic noise filter and high frequency integrated circuit device including the same {MMIC ELECTROMAGNETIC NOISE FILTER AND MICROWAVE INTEGRATED CIRCUIT DEVICE INCLUING THE SAME}

1A and 1B are photographs showing a state in which a radio wave absorber is employed in an integrated circuit device according to a conventional method, respectively.

2A and 2B are a perspective view and a side cross-sectional view, respectively, of an MMIC type electromagnetic noise filter according to an embodiment of the present invention.

FIG. 3 is an equivalent circuit diagram of the MMIC type electromagnetic noise filter shown in FIG. 2A.

4A and 4B are a perspective view and a sectional side view, respectively, of an MMIC type electromagnetic noise filter according to another embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of the MMIC type electromagnetic noise filter shown in FIG. 4A.

6A and 6B are graphs showing electromagnetic noise attenuation characteristics of the MMIC type electromagnetic noise filter manufactured through the embodiment according to the present invention, respectively.

<Explanation of symbols for peripheral parts of the drawing>

21,41: semiconductor substrate 22,42: dielectric thin film

23,43: coplanar signal line 24a, 44a: first coplanar ground line

24b and 44b: second coplanar ground line 46: dielectric layer

48: soft magnetic thin film

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic noise reduction filter, and to a low frequency band pass electromagnetic noise filter and a high frequency integrated circuit device including the same, which can be monolithically employed in a high frequency integrated circuit (Microwave IC).

Recently, the demand for various types of wireless mobile communication systems is rapidly increasing due to the need for rapid information exchange due to diversification and specialization. The core of this wireless mobile communication technology is a high frequency semiconductor device. In general, the term “high frequency semiconductor device” means a semiconductor device manufactured using a semiconductor process among high frequency devices used in a high frequency system capable of high-speed processing of a high frequency band signal of GHz band or higher.

Conventionally, passive elements, single components, and the like have been used to implement a high frequency wireless communication device or circuit. However, there is a problem in reliability at high frequencies, and thus the use of devices using semiconductor technology is increasing. In addition, the development of a single high frequency integrated circuit (Monolithic Microwave IC, MMIC) as a component for information communication that is excellent in high frequency characteristics, small characteristics change according to the signal size, and can integrate various elements of the RF stage into a single chip, And its importance is increasing day by day.

In general, the MMIC component requires a countermeasure for suppressing harmonic noise radiation inevitably generated in nonlinear semiconductor devices embedded in main boards such as wireless mobile communication and portable personal computers. As a conventional solution, a sheet or thin wave absorber has been adopted.

Such a radio wave absorber is a sheet or element of a thickness of several mm made of a composite material in which a green compact, a magnetic material or a dielectric, is incorporated into an organic polymer support material, and is manufactured as a single part separately from nonlinear semiconductor chips that are a source of noise. Used in a manner that is mounted on. 1A and 1B show an example of application of a conventional radio wave absorber.

1A, there is shown an I / O controller hub 1 mounted to a personal computer mainboard. Here, like other nonlinear IC chips, harmonic noise is generated, and in order to remove the noise, a plurality of thin chip-shaped radio wave absorbing elements 2 are mounted around the chip.

1B shows an example of application of the flexible sheet-type wave absorber 4. The flexible sheet-type wave absorber 4 is used in a manner that is only physically in close contact with the upper surface of the IC chip 3.

In the example of the radio wave absorbing element shown in FIG. 1a, since a large area around the main board is required to mount a plurality of radio wave absorbing elements, there is an disadvantage in that the volume and complexity of the overall circuit are excessively increased. FIG. 1b In the case of, it does not cause the volume or complexity of the circuit, but does not have an efficient noise canceling effect.

As described above, the conventional method for reducing noise using a radio wave absorber has a problem that it is difficult to miniaturize by increasing the volume and complexity of the circuit, or to expect an excellent effect of removing noise at an actual high frequency.

In order to solve the above problems of the prior art, an object of the present invention is to minimize the volume and complexity of the circuit by integrally manufacturing the noise filter and non-linear semiconductor elements that are the source of noise on the same semiconductor substrate through a conventional semiconductor process It also provides excellent characteristics in terms of noise removal efficiency.

In order to achieve the above object, one aspect of the present invention,

A first substrate formed on the semiconductor substrate, a dielectric thin film formed on the semiconductor substrate, a coplanar signal line formed on the dielectric thin film, and both ends of which are provided as input / output units, respectively, and formed on the dielectric thin film on both sides of the coplanar signal line. And it provides a MMIC type electromagnetic noise filter including a second coplanar ground line.

The dielectric thin film is a material for providing a dispersion constant capacitance, and preferably, at least one selected from the group consisting of silicon oxide (SiO ₂ ), Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaTiO ₃ and SrTiO ₃ , Can be done.

In a preferred embodiment of the present invention, the coplanar signal line and the first and second coplanar ground lines are additionally formed on a dielectric thin film having a flat top surface, and at least the coplanar signal line and the ground line of the dielectric layer. By further including a soft magnetic thin film formed in a region corresponding to the portion where is formed, an MMIC type electromagnetic noise filter having improved characteristics can be provided.

The dielectric layer added in the present embodiment may be made of at least one selected from the group consisting of silicon oxide (SiO ₂ ), Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaTiO ₃ and SrTiO ₃ , similarly to the dielectric thin film. . Preferably, for the convenience of design and process, the dielectric layer may be formed of the same dielectric material as the dielectric thin film.

The soft magnetic thin film employed in the present embodiment includes a CoFe-based microcrystalline soft magnetic thin film, a Co-based microcrystalline soft magnetic thin film, a Fe-based microcrystalline soft magnetic thin film, a permalloy-based microcrystalline soft magnetic thin film, and a Co-Nb-Zr alloy. Soft magnetic thin film, Fe-based alloy It may be made of a material selected from the group consisting of a soft magnetic thin film, preferably, microcrystalline Co ₄₁ Fe ₃₈ Al ₁₃ O ₈ soft magnetic thin film can be used.

In a specific embodiment of the present invention, the semiconductor substrate may be a silicon substrate or a GaAs substrate mainly used as an integrated circuit substrate, in which case the dielectric thin film and the dielectric layer may use SiO ₂ .

According to another aspect of the present invention, there is provided a semiconductor substrate having a region in which a high frequency integrated circuit including a nonlinear active element is formed, a dielectric thin film formed on at least one region of the upper surface of the semiconductor substrate adjacent to the nonlinear active element, and on the dielectric thin film. And a coplanar signal line having both ends provided as input / output units, and first and second coplanar ground lines respectively formed on the dielectric thin films on both sides of the coplanar transmission line.

Hereinafter, with reference to the accompanying drawings will be described the present invention in more detail.

2A and 2B are a perspective view and a side cross-sectional view, respectively, of an MMIC type electromagnetic noise filter according to an embodiment of the present invention.

Referring to FIG. 2A together with FIG. 2B, the electromagnetic noise filter 20 according to the first embodiment of the present invention is formed on the semiconductor substrate 21 and the dielectric thin film 22 and the dielectric layer 22 formed on the upper surface thereof. The coplanar transmission line structures 23, 24a and 24b are formed. The coplanar transmission line structure includes a coplanar signal line 23 and first and second coplanar ground lines 24a and 24b arranged substantially parallel to both sides.

The semiconductor substrate 21 may be a semiconductor substrate used for manufacturing a conventional integrated circuit device, but is not limited thereto, and may be a silicon (Si) substrate or a GaAs substrate. The region in which the electromagnetic noise filter 20 is implemented in the semiconductor substrate 21 may be understood as a partial region of the semiconductor substrate in which a high frequency integrated circuit including an irreversible device is implemented.

The dielectric thin film 22 is an insulating substrate for implementing the coplanar signal line 23 and the first and second coplanar ground lines 24a and 24b. In the present invention, the dielectric thin film 22 is provided as a dielectric constituting a dispersion constant capacitor. The dielectric layer 22 may be formed of at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaTiO _3, and SrTiO ₃ , and in the case of using a silicon substrate as the semiconductor substrate 21, SiO ₂ may be easily used as the dielectric thin film 22.

The coplanar transmission line structure employed in the present invention is advantageous for high frequency semiconductor devices because it has excellent signal transmission characteristics at high frequencies, has little change in characteristics according to signal size, and is much easier to manufacture than other types of lines. Can be employed.

The coplanar signal lines 23 and coplanar ground lines 24a and 24b may be formed of a material such as copper (Cu) on the dielectric thin film 22. The coplanar transmission line is the width (a, W) and thickness (t) of the signal line 23 and the ground line 24a, and the distance between the two lines is the following Muller and Hilberg equation (Equation 1 Is given by

Equation

here, Z ₀ is the characteristic impedance (50 Ω), ε _ff is the effective dielectric constant of the coplanar transmission line, ε _r is the relative dielectric constant of the substrate, k ₁ , k ₁ ' , k ₂ , k ₂ ' is the width of the coplanar signal line 23 (a), the inner spacing (b) of the coplanar grounding lines 24a and 24b associated with the line spacing, and the outer spacing (c) of the coplanar grounding line related to the width W of the coplanar grounding lines 24a and 24b; , Is a function of the thickness (t) of each line. Based on the above equation, the thickness t and the respective widths (a, W) of the coplanar transmission lines (23, 24a, 24b) can be designed so that the characteristic impedance satisfies 50 Hz.

As described above, the MMIC type electromagnetic noise filter according to the present embodiment uses the L-C resonance principle, and can provide an extremely effective electromagnetic noise shielding effect with a small volume. That is, the energy exchange between the distributed constant inductor element generated in the coplanar signal line 23 itself at the specific resonance frequency and the distributed constant capacitor element generated in the dielectric thin film 22 in combination with the transmission lines 23, 24a and 24b. This happens to maximize the circuit's impedance value. Therefore, from the frequency at which the impedance is maximum, all signals can be reflected and serve as a low pass filter.

Hereinafter, the function as the electromagnetic noise filter shown in FIGS. 2A and 2B will be described with reference to the equivalent circuit diagram of FIG. 3.

As shown in FIG. 3, the characteristic impedance 50 dB may be implemented through an appropriate design based on Equation 1 described above. In addition, the coplanar signal line 23 has a dispersion constant inductance value L generated by itself, and the coplanar transmission lines 23, 24a, 24b and the dielectric thin film 22 that act as conductive electrodes have a dispersion constant capacitance value ( Has C). As such, the structure shown in FIGS. 2A and 2B may constitute an LC resonant filter.

Here, the inductance value C and the capacitance value L of the LC resonant filter can obtain a desired resonance frequency by appropriately modifying the length and width of the coplanar transmission line. For example, when the coplanar transmission line acting as a conductive electrode becomes long, the surface area to which an electric field is applied increases, so that the dispersion constant capacitor value C increases and the inductance value L also increases. As shown in Equation 2 below, the LC resonant frequency f _LC may be lowered and noise reduction may be increased.

[Equation 2]

In this way, the LC resonant frequency can be adjusted through the inductance value L and the capacitance value C by adjusting the length of the coplanar transmission line, and further, the electromagnetic noise attenuation band can be controlled.

4A and 4B are a perspective view and a sectional side view, respectively, of an MMIC type electromagnetic noise filter according to another embodiment of the present invention.

Referring to FIG. 4A, the electromagnetic noise filter 40 according to the second embodiment of the present invention is similar to the structure shown in FIG. 2A, and the dielectric layer 42 and the dielectric layer 42 formed on the semiconductor substrate 41 and the upper surface thereof. 42) coplanar transmission line structures 43, 44a, 44b formed on the substrate. In addition, a dielectric layer 46 having a flat top surface and an additional dielectric layer 46 formed on the dielectric thin film 42 on which the coplanar signal line 43 and the first and second coplanar ground lines 44a and 44b are formed. The soft magnetic thin film 48 formed on at least an area of the upper surface corresponding to the portion where the coplanar transmission lines 43, 44a and 44b are formed is additionally formed.

In this embodiment, components corresponding to the electromagnetic filter described in FIG. 2, that is, the semiconductor substrate 41, the dielectric thin film 42, the coplanar signal line 43, and the first and second coplanar ground lines 44a, 44b) can be designed and formed with the same or similar materials and conditions.

The dielectric layer 46 added in this embodiment not only prevents the short-circuit between the soft magnetic thin film 48 and the coplanar transmission lines 43, 44a and 44b formed thereon, but can also provide additional dispersion constant capacitance. The dielectric layer 46 may be formed of at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaTiO _3, and SrTiO ₃ , similar to the dielectric thin film 42. Preferably, the dielectric layer 46 may be formed of the same dielectric material as the dielectric thin film 42 for the convenience of the process.

In this embodiment, since the dielectric layers 46 and the dielectric thin films 42 are disposed above and below the resonance transmission lines 43, 44a, and 44b, two capacitances can act similarly to a conventional multilayer ceramic capacitor (MLCC). Through this, a higher capacitor effect can be expected.

The soft magnetic thin film 48 employed in the present embodiment is provided to improve the ferromagnetic resonance absorption loss and the eddy current loss effect together with the increase in inductance value of the present filter 40, and coplanar transmission lines according to the filter design conditions. It can be designed to have a suitable size (especially width) around the area corresponding to the part where the furnace is formed. The influence of the width of the soft magnetic thin film will be described in more detail in the second embodiment.

As the constituent material of the soft magnetic thin film 48, a CoFe-based microcrystalline soft magnetic thin film, a Co-based microcrystalline soft magnetic thin film, a Fe-based microcrystalline soft magnetic thin film, a permalloy-based microcrystalline soft magnetic thin film, Co- A material selected from the group consisting of Nb-Zr alloy soft magnetic thin films and Fe-based alloy soft magnetic thin films may be used, and more preferably, microcrystalline Co ₄₁ Fe ₃₈ Al ₁₃ O ₈ soft magnetic thin films may be used.

Also in this embodiment, the coplanar signal line 43 and coplanar ground line 44a and 44b thicknesses and the respective widths and dielectric constants and thicknesses of dielectrics 42 and 46 are described with reference to Equation 1 described in the first embodiment. The characteristic impedance can be designed to satisfy 50 kHz.

As such, the MMIC type electromagnetic noise filter 40 according to the present embodiment can provide an excellent electromagnetic noise shielding effect using the LC resonance principle similarly to FIG. That is, the dispersion constant generated in the dielectric thin film 42 and the dielectric layer 46 in combination with the distributed constant inductor element and the transmission lines 43, 44a, and 44b generated by the coplanar signal line 43 at a specific resonance frequency. In addition to the capacitor element, it is possible to provide higher inductance value and capacitance value than in the first embodiment. Therefore, in the electromagnetic noise filter according to the present embodiment, an electron noise shielding effect improved than the effect expected in the above embodiment can be expected.

Hereinafter, the function as the electromagnetic noise filter shown in FIGS. 4A and 4B will be described with reference to the equivalent circuit diagram of FIG. 5.

As shown in Fig. 5, the characteristic impedance 50 kHz can be implemented through the appropriate design of the electromagnetic noise filter shown in Fig. 4A. The coplanar signal line 46 is generated by itself and has a dispersion constant inductance value L enhanced by the soft magnetic thin film. In addition, along with the coplanar transmission lines 43, 44a and 44b serving as the electrodes of the capacitor, the dielectric thin film and the dielectric layer provide dispersion constant capacitance values C1 and C2, respectively.

As such, the inductance value L and the capacitance values C1 and C2 according to the present embodiment can be increased by the added dielectric layer 46 and the soft magnetic thin film 48, so that the same coplanar transmission line and Under the conditions of the dielectric thin film, the resonance frequency can be lowered and the noise attenuation effect can be increased than in the previous embodiment.

Hereinafter, the electromagnetic noise attenuation effect will be described with reference to specific examples according to the above-described two embodiments.

( Example 1 )

In this embodiment, an electromagnetic noise filter having the same structure as that of FIGS. 2A and 2B was manufactured under the following conditions and processes.

First, SiO ₂ was formed to 2.5 μm on a silicon substrate having a thickness of 500 μm. Subsequently, in order to form a coplanar transmission line, after forming a Cu / Ti seed layer, a Cu layer having a thickness of 3 μm was formed by an electroplating deposition method. Subsequently, the Cu layer is patterned through photolithography and ion milling so that the width (a) of the coplanar signal line, the width (W) of the coplanar ground line, and the distance between the lines are 50 μm and 165 μm, respectively. , Coplanar transmission line structure of 10㎛ was prepared.

Under the same conditions, four electromagnetic noise filters were manufactured, but the coplanar transmission signal lines were changed to 2.2 mm, 5.2 mm, 10.2 mm, and 15.2 mm, respectively, and the change of attenuation characteristics according to the length of the signal line was confirmed by the network analyzer. It was.

6A is a graph showing electromagnetic noise attenuation characteristics of the MMIC type electromagnetic noise filter according to the present embodiment.

As shown in Fig. 6A, when the coplanar transmission signal line length is 2.2 mm at 20 kHz, the attenuation effect is less than -10 dB, but at -17 dB and -34 at 5.2 mm and 10.2 mm, respectively. In case of 15.2㎜, it showed the best attenuation effect (-50dB).

As described above, in the electromagnetic noise filter according to the present invention, the longer the coplanar signal line is, the better the attenuation characteristic is.

In addition, this attenuation value is a value corresponding to the average when compared with a standard generally applied as a level of noise shielding effect, which is similar to the noise attenuation characteristic of a radio wave absorber manufactured using a conventional electromagnetic wave absorbing material. When the noise attenuation value and the attenuation value of the conventional radio wave absorber are normalized and compared with the noise attenuation value per unit volume, it can be seen that the attenuation value is much larger than the area of the present invention. Based on these results, it can be said that the MMIC type electromagnetic noise filter of the present invention has a very efficient electromagnetic noise shielding effect with a small volume.

( Example 2 )

In this embodiment, the electromagnetic noise filter shown in Fig. 4A was manufactured.

First, a coplanar transmission line structure (provided that the coplanar transmission line length is 15.2 mm) is manufactured using the same materials, processes, and conditions as in the first embodiment, and then on the SiO ₂ thin film on which the coplanar transmission line structure is formed. Additional SiO ₂ layers were deposited to a thickness of 3.1 μm with a flat top surface. That is, the SiO ₂ layer was formed so that the thickness of the layer portion added on the coplanar transmission line had 0.1 μm.

Subsequently, Co ₄₁ Fe ₃₈ Al ₁₃ O ₈ soft magnetic thin film having a thickness of 0.5 μm was formed to include a region where the coplanar transmission line was formed among the added SiO ₂ layers. The soft magnetic thin film is made of four electromagnetic noise filters with a length of 15 mm in the length direction of the line, and the width of the additional SiO layer and the soft magnetic thin film is 50 μm, 200 μm, 400 μm, and 2000 μm, respectively. The change of attenuation characteristics with length of was confirmed by a network analyzer.

6B is a graph showing electromagnetic noise attenuation characteristics of the MMIC type electromagnetic noise filter according to the present embodiment.

As shown in FIG. 6B, when the width of the soft magnetic thin film is increased from 50 μm to 200 μm, the noise attenuation effect is increased. However, when the width is increased by more than 200 μm, the noise attenuation effect is saturated at about -90 dB and further increases. It was confirmed not to. The saturation of the noise attenuation effect can be explained by the fact that the effective width affecting the Co ₄₁ Fe ₃₈ Al ₁₃ O ₈ magnetic thin film of the magnetic field radiated from the signal line of the coplanar transmission line is about 200 μm. have.

As such, it was confirmed that the noise attenuation effect was increased by increasing the width of the added dielectric layer and the soft magnetic thin film to an appropriate range. As described above, this is a result of an increase in inductance value due to an increase in the volume of the soft magnetic thin film and an increase in capacitance value due to an increase in the surface area of the silicon oxide layer.

The electromagnetic noise filter according to the present invention may provide a high frequency integrated circuit device in which a miniaturized electromagnetic noise filter is integrated in another area of the substrate in a semiconductor substrate having a region in which a high frequency integrated circuit including a nonlinear active element is formed. In this case, both ends of the coplanar signal line may be provided to the input / output terminal to be connected between the external circuit and the internal integrated circuit.

As such, the present invention is not limited by the above-described embodiments and the accompanying drawings, and is intended to be limited by the appended claims, and various forms of substitution may be made without departing from the technical spirit of the present invention described in the claims. It will be apparent to one of ordinary skill in the art that modifications, variations and variations are possible.

As described above, according to the present invention, the electromagnetic noise filter can be manufactured monolithically with an integrated circuit device in which a nonlinear semiconductor circuit is implemented, thereby minimizing the volume and complexity of the motherboard circuit. Through this, it contributes to the miniaturization and low power trend of portable wireless communication terminals and personal computers, and also reduces the high frequency performance of noise-sensitive semiconductor devices by reducing electromagnetic interference (EMI) effects such as crosstalk. It can be expected to improve.

Claims (10)

Semiconductor substrates; A dielectric thin film formed on an upper surface of the semiconductor substrate; Coplanar signal lines formed on the dielectric thin film and having both ends provided as input / output units; And And a first and a second coplanar ground lines respectively formed on the dielectric thin films on both sides of the coplanar signal lines. The method of claim 1, The dielectric thin film is MMIC electromagnetic noise filter, characterized in that made of at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaTiO ₃ and SrTiO ₃ . The method of claim 1, A dielectric layer additionally formed on the dielectric thin film on which the coplanar signal line and the first and second coplanar ground lines are formed and having a flat upper surface, and an area corresponding to at least the coplanar signal line and the ground line formed portion of the dielectric layer; MMIC electromagnetic noise filter, characterized in that it further comprises a soft magnetic thin film formed. The method of claim 3, And the dielectric layer is made of at least one selected from the group consisting of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ , BaTiO ₃ and SrTiO ₃ . The method of claim 4, wherein MMIC electromagnetic noise filter, characterized in that the dielectric thin film and the dielectric layer is made of the same dielectric. The method of claim 3, The soft magnetic thin film, CoFe-based microcrystalline soft magnetic thin film, Co-based microcrystalline soft magnetic thin film, Fe-based microcrystalline soft magnetic thin film, Permalloy-based microcrystalline soft magnetic thin film, Co-Nb-Zr alloy soft magnetic thin film, Fe-based MMIC type electromagnetic noise filter, characterized in that the material is selected from the group consisting of alloy soft magnetic thin film. The method of claim 6, The soft magnetic thin film is a MMIC electromagnetic noise filter, characterized in that the fine grain Co ₄₁ Fe ₃₈ Al ₁₃ O ₈ soft magnetic thin film. The method of claim 1, The semiconductor substrate is a MMIC electromagnetic noise filter, characterized in that the silicon substrate or GaAs substrate. The method of claim 8, The dielectric thin film is MMIC electromagnetic noise filter, characterized in that SiO ₂ . A semiconductor substrate having a region where a high frequency integrated circuit including a nonlinear active element is formed; A dielectric thin film formed on at least one region of the upper surface of the semiconductor substrate adjacent to the nonlinear active element; Coplanar signal lines formed on the dielectric thin film and having both ends provided as input / output units; And And first and second coplanar ground lines respectively formed on the dielectric thin films on both sides of the coplanar signal line.

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