JPH0590862A - Semiconductor composite element and its production - Google Patents

Abstract

PURPOSE:To provide a device provided with surface acoustic wave elements and their peripheral circuits and that can be miniaturized. CONSTITUTION:The present semiconductor composite element is formed of a semiconductor substrate 1, a diamond layer 2 which is prepared on a predetermined area A on the semiconductor substrate 1, a conductive layer 4 which is prepared over the diamond layer 2 and the semiconductor substrate 1 and at least on the diamond layer 2, formed to interdigital electrodes 5a and 5b, and a piezoelectric body layer 7 which is prepared on the diamond layer 2 so as to hold interdigital electrodes 5a and 5b therebetween. Further, a semiconductor circuit (not shown in the attached drawing) is provided which is prepared in the neighborhood B of the area A where the diamond layer 2 is prepared on the semiconductor substrate 1 and which is electrically connected to the interdigital electrode 5b via a wiring layer 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor composite device including a surface acoustic wave device used for a high frequency filter and its peripheral circuits and a method for manufacturing the same.

[0002]

2. Description of the Related Art A surface acoustic wave element is an electromechanical conversion element utilizing surface waves propagating on the surface of an elastic body, and has a general structure as shown in FIG. In the surface acoustic wave element 20, the piezoelectric phenomenon by the piezoelectric body 21 is used for exciting the surface wave. When an electric signal is applied to one of the comb-shaped electrodes 22 provided on the piezoelectric body 21, distortion is generated in the piezoelectric body 21, which becomes a surface acoustic wave and propagates through the piezoelectric body 21. It is taken out as an electric signal. Frequency characteristics of the device, as shown in FIG, ₀ the period of the electrode in the interdigital electrode lambda, if the velocity of the surface acoustic wave [nu, center frequency f ₀ defined by f ₀ = [nu / lambda ₀ The bandpass characteristics are as follows.

The surface acoustic wave device has a small number of parts, can be made compact, and can easily send and receive signals on the propagation path of the surface wave. This element can be applied to filters, delay lines, oscillators, resonators, convolvers, correlators, and the like. In particular, surface acoustic wave filters have been put to practical use as an intermediate frequency filter for television from early on,
Furthermore, it has been applied to filters for VTRs and various communication devices.

This surface acoustic wave device is composed of LiNbO ₃ and L
It has been manufactured by forming a comb-shaped electrode on a piezoelectric single crystal such as iTaO ₃ , but in recent years, a piezoelectric thin film such as ZnO formed on a substrate such as glass by a technique such as sputtering is used. Is becoming available. However, a piezoelectric thin film such as ZnO formed on glass is usually polycrystalline with orientation, has a large loss due to scattering, and is not suitable for use in a high frequency band of 100 MHz or more.

On the other hand, regarding the surface acoustic wave element, for example, a surface acoustic wave filter used in the field of mobile communication and the like is desired to be an element that can be used in a higher frequency range. As shown in the above equation, when the period λ _{0 of} the electrode becomes smaller or the velocity ν of the surface wave becomes larger, the frequency characteristic of the element has a higher center frequency f ₀ .

Therefore, a surface acoustic wave device has been developed in which a piezoelectric film is laminated on a material (for example, sapphire, diamond, etc.) through which an elastic wave propagates faster (for example, Japanese Patent Laid-Open No. 54-38874 and Japanese Patent Laid-Open No. 38874/1979). JP-A-64
-62911).

[0007]

Among the above-mentioned devices that can be used in the higher frequency range, the devices using diamond are excellent in that f ₀ is increased. In the element using this diamond, for example, the surface acoustic wave filter is used by being connected to an amplifier circuit or the like. In this case, for example, a semiconductor integrated circuit as an amplifier circuit and a surface acoustic wave filter have hitherto been manufactured independently and incorporated into a device. Recently, in mobile communication devices, surface acoustic wave filters have been surface-mounted in devices for downsizing. However,
There is a limit to further downsizing a device including a semiconductor circuit and a surface acoustic wave element in such a form.

An object of the present invention is to provide a device including a surface acoustic wave element and its peripheral circuit, which can be further miniaturized.

[0009]

A semiconductor composite element according to a first invention is an element including at least a surface acoustic wave element, and comprises a semiconductor substrate, a diamond layer provided in a predetermined region on the semiconductor substrate, and a diamond. At least a comb-shaped electrode on the layer, and a conductive layer provided over the diamond layer and the semiconductor substrate, and a piezoelectric layer provided on the diamond layer in close contact with the comb-shaped electrode,
The semiconductor integrated circuit is provided in the vicinity of the region where the diamond layer is provided on the semiconductor substrate, and is electrically connected to the comb electrode through the conductive layer.

A method of manufacturing a semiconductor composite element according to a second aspect of the present invention is a method of manufacturing an element including at least a surface acoustic wave element, which comprises a step of preparing a semiconductor substrate and providing a diamond layer in a predetermined region of the semiconductor substrate. A step of forming a conductive layer that covers the diamond layer and the semiconductor substrate, a step of patterning the conductive layer to form a comb-shaped electrode on at least the diamond layer, and a piezoelectric layer that adheres to the comb-shaped electrode on the diamond layer. The method includes a step of providing a body layer, and a step of forming a semiconductor circuit electrically connected to a comb electrode via a conductive layer in the vicinity of a region where a diamond layer is provided on a semiconductor substrate.

In the first and second inventions, the semiconductor substrate is a semiconductor substrate such as Si and Ge, a III-V group compound semiconductor substrate such as GaAs and InP, and C.
A II-VI group compound semiconductor substrate such as dTe can be used.

The diamond layer according to the first invention may be either single crystal or polycrystalline. The diamond layer can be formed, for example, by vapor phase synthesis using hydrocarbon or the like as a raw material gas, or can be prepared by processing a single crystal diamond synthesized under ultrahigh pressure by a temperature difference method.

The conductive layer according to the first and second inventions is preferably formed of a refractory metal, for example, WA.
By forming the conductive layer with l, W, WN, WSi, or the like, a process under high temperature such as thermal diffusion or annealing after ion implantation can be performed.

The piezoelectric layer according to the first and second inventions comprises:
ZnO, AlN, Pb (Zr, Ti) O ₃ , (Pb, L
a) (Zr, Ti) O ₃ , LiTaO ₃ , LiNb
O ₃ , SiO ₂ , Ta ₂ O ₅ , Nb ₂ O ₅ , BeO, L
i ₂ B ₄ O ₇ , KNbO ₃ , ZnS, ZnSe and C
The main component can be one or more compounds selected from the group consisting of dS. The piezoelectric layer may be either single crystal or polycrystal, but in order to use the device in a higher frequency range, a single crystal with less scattering of surface waves is more preferable.

On the other hand, in the method of manufacturing a semiconductor composite element according to the second aspect of the invention, in the step of providing the diamond layer in a predetermined region of the semiconductor substrate, for example, a predetermined region of the semiconductor substrate is scratched and processed by a vapor phase synthesis method. A method of selectively depositing a diamond layer only on the scratched region, a method of adhering a diamond crystal body to a predetermined region of the substrate, or the like can be used. The vapor-phase synthesis method includes a method of activating a raw material gas by heating an electron emitting material, a method of exciting the raw material gas by plasma, a method of decomposing and exciting the raw material gas by light, and a method of polycrystalline diamond from the raw material gas by ion bombardment. Including the method of growing the. On the other hand, as a method of preparing a diamond crystal body, for example, there is a method of processing a single crystal diamond synthesized under an ultrahigh pressure by a temperature difference method.

When the diamond layer is formed by vapor phase synthesis, the layer immediately after vapor phase synthesis often has low surface resistance. If such a layer is used as it is and an electrode or a piezoelectric body is formed thereon, the electrode or the piezoelectric layer is formed. There is a loss in the voltage applied to the body. Therefore, it is desirable to increase the resistance by oxidizing the layer immediately after the vapor phase synthesis. The oxidation treatment is
For example, the diamond layer may be formed in an oxygen-containing atmosphere of 0.01 Torr or more, particularly preferably 10 Torr or more.
Method of heating above 0 ° C or oxygen partial pressure of above layer is 1
It can be achieved by a method of exposing to oxygen-containing plasma having a pressure of × 10 ^-5 Torr or more. By performing such an oxidation treatment, the resistance value can be increased 10 ⁵ to 10 ¹⁰ times. At this time, for example, when a Si substrate is used, a SiO ₂ film can be formed on the surface of the substrate.

Further, as a method for adhering the diamond crystal body onto the substrate, there are, for example, a method using an adhesive and a brazing method. The adhesive preferably has heat resistance and chemical resistance, and examples thereof include an epoxy resin-based adhesive and an inorganic adhesive. Also heat resistant resins such as aromatic polyamides, polyimides, polyphenyl sulfones and polybenzimidazoles could be used as adhesives.

The desired number of diamond layers can be formed on a substrate at predetermined locations. By forming a surface acoustic wave element and its peripheral circuit for each diamond layer, a plurality of semiconductor composite elements can be formed on the same substrate. The surface of the diamond layer provided on the substrate is preferably polished as needed.

In the step of forming the diamond layer and the conductive layer which covers the semiconductor substrate, a usual method for manufacturing a semiconductor element such as a vapor deposition method, a sputtering method, an ion plating method and a CVD method may be used. In the step of patterning the conductive layer, for example, an etching method may be used.

In the step of forming the piezoelectric layer in the second invention, for example, ZnO, AlN and Pb (Zr, T
i) The piezoelectric layer such as O ₃ can be formed by the CVD method or the sputtering method. Further, in the step of forming the semiconductor circuit, a usual method for manufacturing a semiconductor device may be used.

[0021]

In the composite device provided by the first and second inventions, the surface acoustic wave device composed of the diamond layer, the comb-shaped electrode and the piezoelectric layer and the semiconductor circuit are electrically connected via the conductive layer. Connected to each other and built on the same semiconductor substrate. By monolithicizing the surface acoustic wave element and the semiconductor circuit in this manner, a composite element that processes an electric signal via the surface acoustic wave element with one chip is realized. Such a composite element can be further miniaturized because it is monolithic, and the transmission loss is reduced as the size is reduced. Further, the cost of the device is reduced by making it monolithic.

[0022]

EXAMPLE Referring to FIG. 1A, first, 10 × 10 × 1
A Si single crystal substrate of mm was prepared, and a predetermined region A on its surface was scratched.

Next, the substrate 1 is subjected to microwave plasma CVD.
It is installed in the equipment, the reaction chamber is evacuated, and C
A mixed gas of H ₄ : H ₂ = 1: 200 was introduced at about 20 sccm. The pressure in the reaction chamber was maintained at about 40 mTorr, the substrate temperature was set at 850 ° C., and the power density was 0.8 W /
A plasma layer was formed by discharging at cm ² , and a diamond layer 2 having a thickness of 25 μm was selectively grown only in a predetermined region A of the substrate 1 (FIG. 1 (b)).

Then, the substrate is left in the atmosphere at 450 ° C. for 10 minutes to increase the resistance value of the diamond layer, and the substrate 1
A SiO ₂ film 3 was formed on the surface of the substrate (FIG. 1 (c)).

After polishing the surface of the diamond layer, W is deposited on the diamond layer 2 and the substrate 1 by sputtering.
The Al layer 4 was formed (FIG.1 (d)).

Next, a resist pattern is formed using photolithography, the resist is removed after etching, and the comb-shaped electrodes 5a and 5b are formed on the diamond layer 2.
The necessary wiring pattern 6 was formed on the substrate 1 (see FIG.
(E)).

The substrate was transferred to a magnetron sputtering apparatus, the portion other than the diamond layer 2 was masked, and ZnO was used under the conditions of a sputtering output of 150 W and a substrate temperature of 380 ° C.
Comb-shaped electrode 5a is formed by magnetron sputtering in which a polycrystalline body is sputtered with a mixed gas of Ar: O ₂ = 1: 1.
ZnO film 7 was deposited on and 5b (FIG. 1).
(F)). Then, in the region B shown in FIG. 1F, an amplifier circuit (not shown) electrically connected to the comb-shaped electrode via the WAl layer 4 was manufactured by using a normal semiconductor integrated circuit manufacturing process.

[Brief description of drawings]

FIG. 1 is a cross sectional view schematically showing a manufacturing step of a semiconductor composite element according to the present invention.

FIG. 2 is a perspective view showing a general configuration of a surface acoustic wave device.

[Explanation of symbols]

1 substrate 2 diamond layer 3 SiO ₂ 4 WAl layer 5a, 5b comb electrode 7 ZnO film

Continued Front Page (72) Inventor Naoji Fujimori 1-1-1 Kunyokita, Itami City, Hyogo Prefecture Sumitomo Electric Industries, Ltd. Itami Works

Claims (2)

[Claims] 1. A semiconductor composite device comprising at least a surface acoustic wave device, comprising a semiconductor substrate, a diamond layer provided in a predetermined region on the semiconductor substrate, and at least a comb-shaped electrode on the diamond layer, And a conductive layer provided over the diamond layer and the semiconductor substrate, a piezoelectric layer provided on the diamond layer in close contact with the comb-shaped electrode, and a region of the semiconductor substrate where the diamond layer is provided. A semiconductor composite device, comprising: a semiconductor circuit which is provided in the vicinity and is electrically connected to the comb-shaped electrode through the conductive layer. 2. A method of manufacturing a semiconductor composite device including at least a surface acoustic wave device, comprising: preparing a semiconductor substrate; providing a diamond layer in a predetermined region on the semiconductor substrate; A step of forming a conductive layer covering the semiconductor substrate; a step of patterning the conductive layer so as to form a comb-shaped electrode on at least the diamond layer; and a piezoelectric body in close contact with the comb-shaped electrode on the diamond layer. A semiconductor composite including a step of providing a layer, and a step of forming a semiconductor circuit electrically connected to the comb-shaped electrode via the conductive layer in the vicinity of a region of the semiconductor substrate where the diamond layer is provided. Manufacturing method of device.