JP2861497B2 - Monolithic millimeter wave antenna and method of manufacturing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monolithic millimeter-wave antenna using a compound semiconductor and a method for manufacturing the same.

[0002]

2. Description of the Related Art In recent years, the development of compound semiconductor integrated circuits has been remarkable, and research and development for monolithic integration including not only transmission / reception modules such as millimeter wave radar devices but also antenna elements has been actively conducted. When such monolithic processing is performed, several hundreds of antenna elements with a millimeter wave transmitting / receiving module can be arranged in an array on a GaAs wafer of about 4 inches, and a phased array antenna module is realized.

A conventional monolithic millimeter-wave antenna is a microwave journal (Microwave).
Journal, July 1986, page 119.

FIG. 4 shows a conventional monolithic millimeter wave antenna. FIG. 4A is a plan view, and FIG.
Is a sectional view. On the surface of the semi-insulating GaAs substrate 51, a patch antenna composed of a ground conductor 52, a dielectric 54 having a relative permittivity of εr, and a patch antenna conductor 53 is formed. Is provided with an impedance matching stub 60. 57 and 58 are the gate electrodes of the heterojunction FET, respectively.
The source electrode 59 is a channel layer. Assuming that the antenna length is L, the antenna resonates at a wavelength λg such that λg ≒ 2L, and efficiently radiates electromagnetic waves into space. Where λg
Is the frequency f and the speed of light in a vacuum c.

[0005]

(Equation 1)

[0006] If f = 90 GHz and ε _r = 3, λg is about 2 mm. Therefore, when L = 1 mm, the antenna is for 90 GHz.

[0007]

The conventional patch antenna shown in FIG. 4 resonates in the 90 GHz band at L = 1 mm, but the free space wavelength at 90 GHz is 3.33 m.
m, which is 1.66 mm at 波長 wavelength. That is, εr =
Antenna length 1 mm (λg /
2) is about 60% of a half wavelength in free space, so the current density of the antenna increases and the loss increases,
There is a disadvantage that the energy input to the antenna cannot be efficiently radiated into the space.

An object of the present invention is to provide a high-efficiency monolithic millimeter-wave antenna which eliminates this drawback and a method of manufacturing the same.

[0009]

SUMMARY OF THE INVENTION The present invention relates to a monolithic millimeter-wave antenna in which a millimeter-wave antenna and a millimeter-wave active element are formed on the same semiconductor substrate, and a ground conductor formed on a semi-insulating compound semiconductor substrate. It is characterized in that a patch antenna conductor supported by a plurality of dielectric posts is provided thereon.

The method of manufacturing a monolithic millimeter-wave antenna according to the present invention includes a step of forming a ground metal on a semi-insulating compound semiconductor substrate, a step of forming a dielectric film over the entire surface, and a step of supporting the dielectric film. A step of anisotropically dry-etching the remainder except for the part to be formed, a step of applying a photoresist to the entire surface of the substrate, and a step of flattening the photoresist surface; and A step of partially removing the photoresist on the active element electrode, a step of depositing a feeding metal for gold plating, and a step of forming a photoresist pattern in which a portion serving as a patch antenna conductor and an antenna feeding line is opened, And removing the resist pattern, the power supply metal for gold plating, and the photoresist. That.

[0011]

In the present invention, since the patch antenna conductor is supported in the air by the plurality of dielectric posts, the effective dielectric constant is reduced. Therefore, the antenna length required for resonance approaches one half of the free space wavelength,
The efficiency of the antenna can be greatly increased.

Further, in the manufacturing method of the present invention, even if the size of the dielectric to be a support is on the order of several μm, and the number is plural, the planarization process using a photoresist and the anisotropic dry etching can be used. Since the cueing step is included, a monolithic millimeter-wave antenna can be easily manufactured.

[0013]

FIG. 1 is a diagram showing an embodiment of a monolithic millimeter wave antenna according to the present invention. FIG. 1A is a plan view, and FIG. 1B is a cross-sectional view. In this embodiment, the semi-insulating G
On the surface of the aAs substrate 1, a monolithic patch antenna composed of a ground conductor 2, a dielectric support column 4 having a relative permittivity of εr 4, and a patch antenna conductor 3 is formed, between the antenna feed line 5 and the drain electrode 6 of the hetero junction FET. Is provided with an impedance matching stub 10. 7 and 8 are a gate electrode and a source electrode of the heterojunction FET, respectively, and 9 is a channel layer.

Next, a method of manufacturing the monolithic millimeter-wave antenna according to the present embodiment will be described. FIG. 2 is a cross-sectional view for explaining the manufacturing process.

First, as shown in FIG. 2A, a channel layer 9, a drain electrode 6, a gate electrode 7, and a source electrode 8 are formed.
A ground metal 2 is formed on a semi-insulating GaAs substrate 1 on which a hetero-junction FET composed of is formed.

Next, as shown in FIG. 2B, after an SiO ₂ film is formed on the entire surface of the substrate, anisotropic dry etching is performed using a photoresist or the like as a mask while leaving the support 4 and the passivation film 34. .

Next, as shown in FIG. 2C, a photoresist 15 is spin-coated on the entire surface to flatten the surface of the photoresist 15.

Next, as shown in FIG. 2D, after the dielectric pillar 4 is caught by anisotropic dry etching from the vertical direction, the photoresist on the active element electrode 16 is partially removed. .

Next, as shown in FIG. 3 (e), after a feeding metal TiA17 for plating is deposited on the entire surface, a photoresist pattern 18 is formed in which a portion serving as a patch antenna conductor and an antenna feeding line is opened.

Next, as shown in FIG. 3F, a gold plating layer 19 is selectively formed.

Finally, as shown in FIG. 3 (g), a photoresist layer 18 and a plating feed line 1 under the photoresist layer 18 are formed.
7. By removing the photoresist 15 by ashing with an organic solvent, ion milling, and oxygen plasma, respectively, the monolithic millimeter wave antenna of this embodiment can be obtained. In FIG. 3 (g), reference numeral 20 denotes air.

In the above-described embodiment, the column has a shape (horizontal section is rectangular) extending uniformly in the lateral direction of the antenna. However, the structure of the column is not limited to this, and the horizontal section is square or circular. It goes without saying that another shape may be used.

[0023]

In the monolithic millimeter-wave antenna according to the present invention, the effective dielectric constant approaches 1 because the patch antenna conductor is supported by a plurality of spaced dielectric posts. For this reason, the antenna length required for resonance approaches の of the free space wavelength, and the efficiency of the antenna can be greatly increased.

Further, according to the manufacturing method of the present invention, several μm
A monolithic millimeter-wave antenna having a plurality of dielectric posts on the order can be manufactured.

According to the present invention, a one-chip transceiver including an antenna in a millimeter wave band, a wafer scale phased array radar, and the like can be realized, which has great significance in millimeter wave engineering.

[Brief description of the drawings]

FIG. 1 is a diagram showing a monolithic millimeter-wave antenna according to one embodiment of the present invention.

FIG. 2 is a cross-sectional view for explaining a method of manufacturing the monolithic millimeter wave antenna of FIG.

FIG. 3 is a cross-sectional view for describing a method of manufacturing the monolithic millimeter wave antenna of FIG.

FIG. 4 is a diagram showing a conventional monolithic millimeter wave antenna.

[Explanation of symbols]

 1,51 Semi-insulating GaAs substrate 2,52 Ground conductor 4,54 Dielectric 3,53 Patch antenna conductor 5,55 Feed line 10,60 Stub 6,56 Drain electrode 7,57 Gate electrode 8,58 Source electrode 9, 59 Channel transmission 34 Passivation film

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H01Q 13/08 H01Q 23/00

Claims (2)

(57) [Claims] A monolithic millimeter-wave antenna in which a millimeter-wave antenna and a millimeter-wave active element are formed on the same semiconductor substrate, wherein a plurality of dielectric posts are provided on a ground conductor formed on a semi-insulating compound semiconductor substrate. A monolithic millimeter-wave antenna comprising a supported patch antenna conductor. 2. A step of forming a ground metal on a semi-insulating compound semiconductor substrate, a step of forming a dielectric film over the entire surface, and anisotropically removing a portion of the dielectric film except for a portion to be a support. A step of dry-etching, a step of applying a photoresist to the entire surface of the substrate, and a step of planarizing the photoresist surface; Forming a photoresist pattern in which a portion serving as a patch antenna conductor and an antenna feed line is opened, and performing a gold plating process; and A method for manufacturing a monolithic millimeter-wave antenna, comprising: a step of removing a feed metal and the photoresist.