CN102201455A - Index-doped GaAs (Gallium Arsenide) Schottky variable capacitance diode and production method of same - Google Patents

Abstract

The invention relates to the technical field of microwave, and discloses an index-doped GaAs (Gallium Arsenide) Schottky variable capacitance diode. The diode comprises a semiconductor insulating GaAs substrate, a heavy-doped N+ layer, an N type layer, an upper electrode and a lower electrode, wherein the heavy-doped N+ layer is grown on the semiconductor insulating GaAs substrate in an epitaxial manner; the N type layer is grown on the N+ layer in an epitaxial manner, and the doping concentration of the N type layer is in exponential distribution; the upper electrode is used for evaporating a Schottky contact on the index-doped N type layer; and the lower electrode is used for evaporating metal on the N+ layer to form an ohmic contact. The invention simultaneously discloses a production method of the index-doped GaAs Schottky variable capacitance diode. When the index-doped GaAs Schottky variable capacitance diode is used, under the condition that the structure of the traditional Schottky diode is not changed, the doping concentration of the N type layer can be changed, the variable capacitance ratio of the GaAs Schottky variable capacitance diode can be increased, and the nonlinearity of the GaAs Schottky variable capacitance diode can be enhanced; moreover, the GaAs Schottky variable capacitance diode can be used in a periodic nonlinear transmission line; and therefore, the working frequency and output power of a frequency multiplier circuit within the range of millimeter waves and submillimeter waves are improved.

Description

GaAs Schottky variable capacitance diode of a kind of exponential doping and preparation method thereof

Technical field

The present invention relates to diode technologies field in the microwave device, relate in particular to GaAs Schottky variable capacitance diode of a kind of exponential doping and preparation method thereof.

Background technology

Schottky barrier diode is the nonlinear device commonly used in the microwave frequency multiplier circuit, because the Schottky barrier diode preparation process is simple, structure is flexible, so be used on the frequency multiplier circuit in the millimeter wave, submillimeter wave scope its operating frequency height, power output height more.

Traditional Schottky barrier diode adopts evenly doping at N type layer.The Schottky variable capacitance pipe variable compression ratio of this doping is little, non-linear a little less than, seriously limited millimeter wave, the operating frequency and the power output of frequency multiplier circuit in the submillimeter wave scope.

Summary of the invention

(1) technical problem that will solve

In view of this, GaAs Schottky variable capacitance diode that provides a kind of exponential doping and preparation method thereof is provided main purpose of the present invention, under the prerequisite that does not change Schottky diode structure, to change N type layer doping content, improve GaAs Schottky variable capacitance diode variable compression ratio, strengthen non-linear, improve millimeter wave, the operating frequency and the power output of frequency multiplier circuit in the submillimeter wave scope.

(2) technical scheme

For achieving the above object, the invention provides a kind of GaAs Schottky variable capacitance diode of exponential doping, comprising:

Be used to support the semiconducting insulation GaAs substrate of whole GaAs Schottky variable capacitance diode;

Epitaxially grown heavily doped N on semiconducting insulation GaAs substrate ⁺Layer;

At N ⁺Continue the N type layer of epitaxially grown exponential doping on the layer;

Through digging the island, isolate two processing steps, at N type layer, N ⁺The mesa structure that forms on the layer;

The top electrode of the Schottky contacts that evaporated metal forms on N type layer; And

At N ⁺The bottom electrode of the ohmic contact that evaporated metal forms on the layer.

In the such scheme, the described top electrode that on the N of exponential doping type layer, forms, the metal of employing is Al/Ti/Au.

In the such scheme, the exponential doping of described N type layer is: doping content N=N ₀* exp (x/d ₀), N wherein ₀=2e17, d ₀=225nm, x are the distance with the material upper surface; As seen N ⁺The upper surface place of layer is highly doped, N type layer and N ⁺Layer intersection is low-doped; Doping content satisfies this exponential distribution in from the surface to the semiconductor bulk.

In the such scheme, described at N ⁺The bottom electrode that forms on the layer, the metal of employing is Ni/Ge/Au/Ge/Ni/Au.

For achieving the above object, the present invention also provides a kind of manufacture method of GaAs Schottky variable capacitance diode, and this method comprises:

A, on semiconducting insulation GaAs substrate the highly doped N of epitaxial growth ⁺Layer;

B, the N type layer that growth index is mixed on the N+ layer;

C, employing wet etching reduce the area of N type layer, form N type layer and N ⁺The mesa structure of layer;

D, at N ⁺The difference evaporated metal forms ohmic contact and Schottky contacts on layer and the N type layer;

E, employing wet etching reduce N ⁺The area of layer forms N ⁺The mesa structure of layer and dielectric substrate.

In the such scheme, this method further comprises: at whole diode component surface deposition silicon nitride, adopt the silicon nitride of dry etching deposit to open the lead-in wire window.

(3) beneficial effect

From technique scheme as can be seen, the present invention has following beneficial effect:

1, the GaAs Schottky variable capacitance diode of this exponential doping provided by the invention, N type layer adopts exponential doping.The variable capacitance diode variable compression ratio height of this structure, non-linear strong, help the raising of millimeter wave frequency multiplier circuit power output.

2, the GaAs Schottky variable capacitance diode of this exponential doping provided by the invention, N type layer and N ⁺Layer forms mesa structure, N ⁺Evaporated metal forms bottom electrode on the layer, and evaporated metal forms top electrode on the N type layer.Upper and lower electrode is drawn from the same side, and this structure is flexible, is easy to be applied in the frequency multiplier circuit, and does not need the carrier device of large volume.

3, the GaAs Schottky variable capacitance diode of this exponential doping provided by the invention is simple for production, and better high frequency characteristics is arranged.

Description of drawings

The doping content of the exponential doping of the N type layer that Fig. 1 selects for use for the present invention and change curve apart from case depth;

Fig. 2 is the GaAs Schottky variable capacitance diode C-V simulation curve of exponential doping provided by the invention;

Fig. 3 is the GaAs Schottky variable capacitance diode I-V simulation curve of exponential doping provided by the invention;

Fig. 4 is the sectional view of the GaAs Schottky variable capacitance diode of exponential doping provided by the invention;

Fig. 5 is the vertical view of the GaAs Schottky variable capacitance diode of exponential doping provided by the invention;

Fig. 6 is the method flow diagram of making GaAs Schottky variable capacitance diode provided by the invention.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.

As shown in Figure 4, Fig. 4 is the sectional view of GaAs Schottky variable capacitance diode provided by the invention.Described sectional view is the sectional view perpendicular to substrate along GaAs Schottky variable capacitance diode bottom electrode two ends.This GaAs Schottky diode comprises:

Be used to support the semiconducting insulation GaAs substrate of whole GaAs Schottky variable capacitance diode;

Epitaxially grown highly doped N on the semiconducting insulation substrate ⁺Layer is at N ⁺Continue the N type layer of epitaxially grown exponential doping on the layer.Through digging the island, isolate two processing steps, N type layer, N ⁺The mesa structure that layer forms;

Evaporated metal forms the top electrode of Schottky contacts on N type layer;

Evaporated metal forms the bottom electrode of ohmic contact on the N+ layer.

As shown in Figure 5, Fig. 5 is the vertical view of GaAs Schottky variable capacitance diode provided by the invention.In conjunction with Fig. 4 and Fig. 5 as can be known, this diode provided by the invention is a kind of mesa structure, and upper and lower electrode is drawn by lead-in wire from the same side.This structure applications has very big flexibility in circuit, it is integrated to be convenient to monolithic, saves cost.

Based on Fig. 4 and GaAs Schottky variable capacitance diode schematic diagram shown in Figure 5, Fig. 6 shows the method flow diagram of making GaAs Schottky variable capacitance diode provided by the invention, and this method may further comprise the steps:

Step 1, on semi-insulating substrate by the method for the molecular beam epitaxy highly doped N that grows ⁺Layer, it is IVA family elements such as Si that element is mixed by institute, doping content is 10 ¹⁸/ cm ³Magnitude.

Step 2, at N ⁺The N type layer that mixes by the method growth index of molecular beam epitaxy on the layer, doped chemical is IVA family elements such as Si, and doping content satisfies exponential distribution, and the surface is the concentration maximum, can be 10 ¹⁷/ cm ³Magnitude, N type layer and place, N+ bed boundary reach minimum and can be 10 ¹⁶/ cm ³

Step 3, employing wet etching reduce the area of N type layer, form N type layer and N ⁺The mesa structure of layer;

Step 4, at N ⁺Evaporate respectively on layer and the N type layer and form ohmic contact and Schottky contacts.

Step 5, employing wet etching reduce N ⁺The area of layer forms N ⁺The mesa structure of layer and dielectric substrate.

Step 6, at whole diode component surface deposition silicon nitride, adopt the silicon nitride of dry etching deposit to open the lead-in wire window.

Above-described specific embodiment; purpose of the present invention, technical scheme and beneficial effect are further described; institute is understood that; the above only is specific embodiments of the invention; be not limited to the present invention; within the spirit and principles in the present invention all, any modification of being made, be equal to replacement, improvement etc., all should be included within protection scope of the present invention.

Claims (6)

1. the GaAs Schottky variable capacitance diode of an exponential doping is characterized in that, comprising:

Be used to support the semiconducting insulation GaAs substrate of whole GaAs Schottky variable capacitance diode;

Epitaxially grown heavily doped N on semiconducting insulation GaAs substrate ⁺Layer;

At N ⁺Continue the N type layer of epitaxially grown exponential doping on the layer;

Through digging the island, isolate two processing steps, at N type layer, N ⁺The mesa structure that forms on the layer;

The top electrode of the Schottky contacts that evaporated metal forms on N type layer; And

At N ⁺The bottom electrode of the ohmic contact that evaporated metal forms on the layer.

2. GaAs Schottky variable capacitance diode according to claim 1 is characterized in that, the described top electrode that on the N of exponential doping type layer, forms, and the metal of employing is Al/Ti/Au.

3. GaAs Schottky variable capacitance diode according to claim 1 is characterized in that, the exponential doping of described N type layer is:

Doping content N=N ₀* exp (x/d ₀), N wherein ₀=2e17, d ₀=225nm, x are the distance with the material upper surface; N ⁺The upper surface place of layer is highly doped, N type layer and N ⁺The layer intersection be low-doped, from the surface to the semiconductor bulk in doping content satisfy this exponential distribution.

4. GaAs Schottky variable capacitance diode according to claim 1 is characterized in that, and is described at N ⁺The bottom electrode that forms on the layer, the metal of employing is Ni/Ge/Au/Ge/Ni/Au.

5. the manufacture method of a GaAs Schottky variable capacitance diode is characterized in that, this method comprises:

A, on semiconducting insulation GaAs substrate the highly doped N of epitaxial growth ⁺Layer;

B, the N type layer that growth index is mixed on the N+ layer;

C, employing wet etching reduce the area of N type layer, form N type layer and N ⁺The mesa structure of layer;

D, at N ⁺The difference evaporated metal forms ohmic contact and Schottky contacts on layer and the N type layer;

E, employing wet etching reduce N ⁺The area of layer forms N ⁺The mesa structure of layer and dielectric substrate.

6. the manufacture method of GaAs Schottky variable capacitance diode according to claim 5 is characterized in that, this method further comprises: at whole diode component surface deposition silicon nitride, adopt the silicon nitride of dry etching deposit to open the lead-in wire window.

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