JPH0529826A - Monolithic millimeter wave antenna and production method - Google Patents

Abstract

PURPOSE:To provide a monolithic millimeter wave antenna having a good radiant efficiency. CONSTITUTION:In a monolithic millimeter wave antenna which a millimeter wave antenna element and an active device are formed on a same semiconductor substrate, a patch antenna conductor 3 is supported by a dielectric substance support 14 in the air and an effective dielectric constant is lowered. The loss caused by the antenna itself whose current density lowers is drastically reduced because an antenna length L can be brought close to free space 1/2 wavelength.

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 monolithically integrating not only transmission / reception modules such as millimeter wave radar devices but also antenna elements have been actively conducted. By performing such monolithic processing, several hundreds of antenna elements with millimeter wave transmitting / receiving modules can be arranged in an array on a GaAs wafer of about 4 inches to realize a phased array antenna module.

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

FIG. 4 is a diagram showing a conventional monolithic millimeter-wave antenna. 4 (a) is a plan view, and FIG. 4 (b).
Is a sectional view. A patch antenna including a ground conductor 52, a dielectric 54 having a relative permittivity εr, and a patch antenna conductor 53 is formed on the surface of the semi-insulating GaAs substrate 51, and the antenna is connected between the antenna feed line 55 and the drain electrode 56 of the heterojunction FET. Is provided with an impedance matching stub 60. 57 and 58 are gate electrodes of the heterojunction FET,
The source electrode 59 is a channel layer. Assuming that the antenna length is L, the antenna resonates with respect to a wavelength λg of λg≈2L and efficiently radiates an electromagnetic wave into space. Where λg
Where f is the frequency and c is the speed of light in a vacuum,

[0005]

[Equation 1]

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

[0007]

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

An object of the present invention is to provide a highly efficient monolithic millimeter-wave antenna and a method for manufacturing the same, in which this drawback is eliminated.

[0009]

SUMMARY OF THE INVENTION The present invention is 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 it is provided with a patch antenna conductor supported on a plurality of dielectric support columns.

The method for manufacturing a monolithic millimeter-wave antenna according to the present invention further comprises a step of forming a ground metal on a semi-insulating compound semiconductor substrate, a step of forming a dielectric film on the entire surface, and a pillar of the dielectric film. After anisotropic dry etching of the remaining portion except the portion to be formed, a step of applying a photoresist to the entire surface of the substrate and flattening the photoresist surface, and after the dielectric is cueed by anisotropic dry etching , A step of partially removing the photoresist on the active element electrode, a step of vapor-depositing a feeding metal for gold plating, and a step of forming a photoresist pattern in which a patch antenna conductor and a portion serving as an antenna feeding line are opened, and gold plating And a step of removing the resist pattern, the gold-plating power supply metal, and the photoresist. That.

[0011]

In the present invention as described above, since the patch antenna conductor is supported in the air by the plurality of dielectric support columns, the effective permittivity is lowered. Therefore, the antenna length required for resonance approaches 1/2 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 the pillar is of the order of several μm, and the number of dielectrics is plural, the flattening step by the photoresist and the anisotropic dry etching can be performed. A monolithic millimeter-wave antenna can be easily manufactured because it includes a cueing process.

[0013]

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

Next, a method for manufacturing the monolithic millimeter-wave antenna of this embodiment will be described. FIG. 2 shows 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 having a heterojunction FET formed of.

Next, as shown in FIG. 2B, after a SiO ₂ film is formed on the entire surface of the substrate, anisotropic dry etching is performed by using the photoresist or the like as a mask and 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. 3D, after the dielectric support pillars 4 are indexed by anisotropic dry etching from the vertical direction, the photoresist on the active element electrodes 16 is partially removed. .

Next, as shown in FIG. 3 (e), a plating feed metal TiAu 17 is vapor-deposited on the entire surface, and then a photoresist pattern 18 is formed in which portions to be the patch antenna conductor and the antenna feed line are opened.

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

Finally, as shown in FIG. 3 (g), the photoresist layer 18 and the plating feed line 1 below the photoresist layer 18 are provided.
7. Further, the photoresist 15 is removed by ashing with an organic solvent, ion milling, and oxygen plasma, respectively, to obtain the monolithic millimeter-wave antenna of this embodiment. In addition, 20 in FIG. 3 (g) represents air.

In the above embodiments, the support pillar has a shape that extends uniformly in the lateral direction of the antenna (the horizontal cross section is rectangular), but the structure of the support pillar is not limited to this, and the horizontal cross section has a square shape, a circular shape, or the like. It goes without saying that it may have another shape.

[0023]

In the monolithic millimeter-wave antenna of the present invention, since the patch antenna conductor is supported by the plurality of spaced dielectric posts, the effective dielectric constant approaches 1. Therefore, the antenna length required for resonance approaches ½ of the free space wavelength, and the antenna efficiency can be greatly increased.

Further, according to the manufacturing method of the present invention, several μm
A monolithic millimeter-wave antenna can be manufactured that has multiple order dielectric rods.

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

[Brief description of drawings]

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

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

FIG. 3 is a cross-sectional view for explaining the 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 feeder line 10,60 stubs 6,56 drain electrode 7,57 Gate electrode 8,58 Source electrode 9,59 channel transmission 34 Passivation film

Claims (2)

[Claims] 1. 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 support pillars are provided on a ground conductor formed on a semi-insulating compound semiconductor substrate. A monolithic millimeter-wave antenna characterized by having 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 on the entire surface, and anisotropy of the remainder of the dielectric film except for the pillars. Step of dry etching, step of applying photoresist to the entire surface of the substrate and flattening the photoresist surface, and step of removing the photoresist on the active element electrode partially after the dielectric is cueed by anisotropic dry etching. A step of forming a photoresist pattern in which a feeding metal for gold plating is vapor-deposited, and a patch antenna conductor and a portion to be an antenna feeding line are opened, a step of performing gold plating, the resist pattern, the gold plating A method of manufacturing a monolithic millimeter-wave antenna, comprising: a feeding metal; and a step of removing the photoresist.