CN104143592B - The processing method and gallium nitride device of a kind of gallium nitride device - Google Patents

Abstract

An embodiment of the present invention provides a processing method for a gallium nitride device. The processing method is as follows: laying an oxide layer on the surface of the gallium nitride device, the material of the oxide layer is an electrically insulating material, and the oxide layer is Etching is performed to retain the oxide layer on the sidewall of the step of the gallium nitride device, and remove the oxide layer of other parts except the sidewall of the step. The invention also discloses a gallium nitride device. By adopting the present invention, the metal layers on the front and rear sides of the above-mentioned step can be completely etched away, avoiding metal residues on the side walls on the front and back sides of the step in metal etching, and preventing the source (S) and drain of the gallium nitride device from (D) The metal is short-circuited and interconnected, and effectively isolates the gate metal of the GaN device and the conductive channel of the GaN device, preventing leakage of the GaN device.

Description

A kind of processing method of gallium nitride device and gallium nitride device

technical field

The invention relates to the field of semiconductors, in particular to a processing method of a gallium nitride device and a gallium nitride device.

Background technique

At present, the international semiconductor industry has entered the era of the third-generation wide bandgap semiconductor represented by gallium nitride (GaN) materials, silicon carbide (SIC) materials and diamond. Gallium nitride material has wide direct band gap, strong atomic bond, high thermal conductivity, good chemical stability and strong radiation resistance. It is widely used in optoelectronics, high-temperature high-power devices and high-frequency microwave devices. Has a broad prospect.

The manufacturing process of most gallium nitride devices is: epitaxially growing aluminum nitride nuclei (AlNnucleation) on the substrate material, growing gallium nitride epitaxy on the nucleation layer, and growing gallium nitride epitaxially on the gallium nitride layer , and then grow a layer of silicon-doped aluminum gallium nitride (AlGaN) on the gallium nitride layer, form a two-dimensional electron gas and heterojunction channel between the channels of aluminum gallium nitride and gallium nitride, and finally use A thin passivation layer protects the two-dimensional electron gas and the surface of the heterojunction channel.

In the process of making gallium nitride devices such as diodes, transistors and photodetectors based on gallium nitride materials, gallium nitride devices need to be etched. Etching technology is generally divided into: wet etching technology and dry etching technology. Wet etching uses a pattern transfer method that removes unnecessary films through chemical reactions in chemical solutions. Since gallium nitride materials have high bonding energy and stable chemical properties (almost not corroded by any acid), gallium nitride The material is practically insoluble in common solutions. Therefore, the etching of gallium nitride devices generally does not use wet etching, but uses dry etching. Dry etching uses ions or atoms with certain energy to achieve the purpose of etching through physical bombardment or chemical corrosion of ions, or the synergistic effect of the two.

Due to the special structure and etching characteristics of gallium nitride devices in the prior art, the following technical problems exist in the prior art:

Question one:

As shown in Figure 1, there is a step between the source (S) and drain (D) of the GaN device. After the metal layer is deposited on the surface of the gallium nitride device, the metal layer is etched, because the metal layer deposited on the surface of the gallium nitride device will form a 90° right angle with the side wall of the above-mentioned step, and because When etching a gallium nitride device, it is necessary to place the silicon wafer (wafer) perpendicular to the etching gas flow to obtain good etching characteristics, so it is difficult to deposit metal on the side wall of the step of the gallium nitride device. If it is etched clean, it will remain within the 90° right angle between the surface of the GaN device and the sidewall of the above-mentioned step, causing the source (S) and drain (D) to be short-circuited and interconnected, resulting in a GaN device short circuit.

Figure 2 and Figure 3 are cross-sectional views of the GaN device shown in Figure 1 along the gate (AA' direction).

Figure 2 is the morphology of the gallium nitride device before metal etching, it can be seen that at this time, the metal layer deposited on the surface of the gallium nitride device and the side wall metal of the step of the gallium nitride device form a 90° right angle.

Fig. 3 is the morphology of the gallium nitride device after metal etching, it can be seen that at this time, after the metal etching of the gallium nitride device, the gap between the surface of the gallium nitride device and the side wall of the above-mentioned step In the 90° right angle, there are some sidewall metal residues that are difficult to etch away. The sidewall metal residues cause the source (S) and drain (D) of the GaN device to form a short-circuit interconnection, resulting in a GaN device short circuit.

Question two:

FIG. 4 is a sectional view of FIG. 1 along the gate direction (AA' direction).

As shown in Figure 4, there is a special conductive channel between the GaN layer and the AlGaN layer of the GaN device. Since the special conductive layer of the GaN device is a thin layer of two-dimensional electron gas, when the gate metal is fabricated on the GaN device, when the gate metal spans the entire step, the gate metal will contact with the above-mentioned conductive trench. The channel is connected, resulting in leakage of GaN devices.

Contents of the invention

An embodiment of the present invention provides a processing method of a gallium nitride device and a gallium nitride device, which are used to prevent the gallium nitride device from being damaged due to the short-circuit interconnection between the source (S) and the drain (D) of the gallium nitride device. Short circuits, and the leakage of GaN devices due to the contact between the gate metal of the GaN device and the conductive channel of the GaN device.

Laying an oxide layer on the surface of the gallium nitride device, the material of the oxide layer is an electrically insulating material;

The oxide layer is etched to retain the oxide layer on the sidewall of the step of the gallium nitride device, and remove the oxide layer of other parts except the sidewall of the step.

A gallium nitride device, the gallium nitride device comprising:

a step, a source (S) and a drain (D) respectively located on the left and right sides of the step, and a gate (G) straddling the step; and,

An oxide layer is deposited on the side wall of the step, and the material of the oxide layer is an electrical insulating material.

In the embodiment of the present invention, an oxide layer is deposited on the surface of the gallium nitride device, and the material of the oxide layer is an electrically insulating material, and the oxide layer is etched to retain the steps of the gallium nitride device the oxide layer on the sidewall of the step, and remove the oxide layer on other parts of the step except the sidewall.

As shown in FIG. 6 , an oxide layer, ie, a sidewall, is formed on the sidewall of the step of the GaN device. After adding the sidewall, the angle between the oxide layer on the sidewall of the step and the surface of the GaN device is much greater than 90°. When etching the metal layer deposited on the surface of the gallium nitride device, the metal layers on the front and rear sides of the step can be completely removed, so as to avoid metal residues on the sidewalls on the front and back sides of the step during metal etching. Effectively prevent short interconnection between source and drain of GaN devices. Moreover, the gate metal and the conductive channel of the GaN device can be effectively isolated, thereby protecting the conductive channel of the GaN device and preventing the leakage of the GaN device.

Description of drawings

FIG. 1 is a schematic diagram of a gallium nitride device in the prior art;

Fig. 2 is a schematic diagram of a cross-sectional view of a gallium nitride device along the gate (AA' direction) in the prior art;

3 is a schematic diagram of the morphology of gallium nitride devices in the prior art after metal etching;

FIG. 4 is a schematic diagram of the morphology of the gallium nitride device in the prior art after the gate metal is fabricated;

FIG. 5 is a schematic flow chart of a processing method of a gallium nitride device in an embodiment of the present invention;

6 is a schematic diagram of the morphology of the gallium nitride device before metal etching in the embodiment of the present invention;

Fig. 7 is a schematic diagram of the morphology of the gallium nitride device after depositing metal in the embodiment of the present invention;

FIG. 8 is a schematic structural diagram of the left and right sides of the steps of the gallium nitride device in the embodiment of the present invention;

FIG. 9 is a schematic diagram of the morphology of the gallium nitride device after metal etching in the embodiment of the present invention;

FIG. 10 is a schematic diagram of the morphology of the gallium nitride device after the gate metal is fabricated in the embodiment of the present invention;

FIG. 11 is a schematic diagram of the structure after fabrication of the source, drain and gate in the embodiment of the present invention.

detailed description

To provide a method for preventing short-circuiting of GaN devices due to source (S) and drain (D) shorted interconnects of GaN devices, and The solution to the GaN device leakage caused by the contact of the conductive channels of the device, the embodiment of the present invention provides a processing method of the GaN device, in this method, an oxide layer is deposited on the surface of the GaN device , the material of the oxide layer is an electrically insulating material, and the oxide layer is etched to retain the oxide layer on the sidewall of the step of the gallium nitride device, and remove the other parts of the sidewall of the step oxide layer. .

Referring to Fig. 5, the processing method of the gallium nitride device provided by the present invention specifically includes the following steps:

Step 50: laying an oxide layer on the surface of the gallium nitride device, the material of the oxide layer is an electrical insulating material;

Step 51: Etching the oxide layer (for example, dry etching may be used), so as to retain the oxide layer on the sidewall of the step of the gallium nitride device, and remove the part other than the sidewall of the step oxide layer.

Further, after etching the above-mentioned oxide layer to retain the oxide layer on the sidewall of the step of the above-mentioned gallium nitride device, and remove the oxide layer of other parts other than the sidewall of the step, the above-mentioned A metal layer is deposited on the surface of the gallium nitride device; the metal layer is etched to retain the metal layer on the left and right sides of the above step, and remove the metal layer on the front and back sides of the above step, and the above step The metal layer on one of the left and right sides serves as the source of the gallium nitride device, and the metal layer on the other side serves as the drain of the gallium nitride device.

Further, after the metal layer is etched to retain the metal layers on the left and right sides of the step and remove the metal layers on the front and back sides of the step, a layer can be deposited on the surface of the gallium nitride device again. layer metal layer; etch the metal layer deposited again to retain the metal layer across the above step and remove the metal layer in other parts, and use the metal layer across the above step as the gate of the gallium nitride device .

Preferably, the oxide layer is made of silicon dioxide or silicon nitride.

Further, the thickness of the oxide layer is slightly smaller or not smaller than the thickness of the step.

Embodiment one:

Step 1: Lay an oxide layer on the surface of the gallium nitride device. The material of the above oxide layer is an electrically insulating material. The oxide layer covers all the surfaces of the gallium nitride device, especially including the steps of the gallium nitride device all surfaces.

Step 2: Etching the oxide layer (for example, dry etching can be used) to retain the oxide layer on the side wall of the step of the gallium nitride device, that is, the side wall in Figure 6, and remove the step Oxide layer on parts other than sidewalls.

Wherein, the material of the oxide layer is an electrical insulation material, and the electrical insulation material includes all materials that can prevent the passage of electric current. Since silicon dioxide and silicon nitride have superior electrical insulation and process feasibility, the present invention uses silicon dioxide And silicon nitride as the oxide layer, the performance is better.

Step 3: Referring to Figure 7, after etching the oxide layer, lay a metal layer on the surface of the gallium nitride device, and etch the metal layer to retain the metal on the left and right sides of the above step layer, and remove the metal layers on the front and rear sides of the above-mentioned step, and use one of the metal layers on the left and right sides of the above-mentioned step as the source of the gallium nitride device, and the metal layer on the other side as the gallium nitride device the drain. Wherein, referring to FIG. 8 , 80 is the left side of the step, 81 is the right side of the upper step, 82 is the front side of the step, and 83 is the rear side of the step.

Preferably, when the thickness of the oxide layer is slightly less than or not less than the thickness of the above-mentioned step (the above-mentioned slightly smaller means that the difference between the thickness of the oxide layer and the thickness of the above-mentioned step is less than the threshold value, for example, the threshold value can be 10nm), the angle between the metal layer deposited on the side wall of the step and the metal layer deposited on the surface of the gallium nitride device is much greater than 90°, and the step can be completely removed during metal etching The metal layers on the front and rear sides are as shown in FIG. 9 . At this time, there is no sidewall metal remaining on the front and back sides of the step, which will not cause short-circuit interconnection between the source and drain of the GaN device.

Embodiment two:

Step 1: Lay an oxide layer on the surface of the gallium nitride device. The material of the above oxide layer is an electrically insulating material. The oxide layer covers all the surfaces of the gallium nitride device, especially including the steps of the gallium nitride device all surfaces.

Step 2: Etching the oxide layer (for example, dry etching can be used) to retain the oxide layer on the side wall of the step of the gallium nitride device, that is, the side wall in Figure 6, and remove the step Oxide layer on parts other than sidewalls.

Wherein, the material of the oxide layer is an electrical insulation material, and the electrical insulation material includes all materials that can prevent the passage of electric current. Since silicon dioxide and silicon nitride have superior electrical insulation and process feasibility, the present invention uses silicon dioxide And silicon nitride as the oxide layer, the performance is better.

Step 3: Referring to Figure 7, after etching the oxide layer, lay a metal layer on the surface of the gallium nitride device, and etch the metal layer to retain the metal on the left and right sides of the above step layer, and remove the metal layers on the front and rear sides of the above-mentioned step, and use one of the metal layers on the left and right sides of the above-mentioned step as the source of the gallium nitride device, and the metal layer on the other side as the gallium nitride device the drain. Wherein, referring to FIG. 8 , 80 is the left side of the step, 81 is the right side of the step, 82 is the front side of the step, and 83 is the rear side of the step.

Preferably, when the thickness of the oxide layer is slightly less than or not less than the thickness of the above-mentioned step (the above-mentioned slightly smaller means that the difference between the thickness of the oxide layer and the thickness of the above-mentioned step is less than the threshold value, for example, the threshold value can be 10nm), the angle between the metal layer deposited on the side wall of the step and the metal layer deposited on the surface of the gallium nitride device is much greater than 90°, and the step can be completely removed during metal etching The metal layers on the front and rear sides are as shown in FIG. 9 . At this time, there is no sidewall metal remaining on the front and back sides of the step, which will not cause short-circuit interconnection between the source and drain of the GaN device.

Step 4: Referring to Figure 10, deposit a metal layer on the surface of the gallium nitride device again; etch the metal layer deposited again to retain the metal layer across the above steps and remove the metal in other parts layer, and the metal layer across the above step is used as the gate of the gallium nitride device.

Among them, the device structure after the source, drain and gate of the gallium nitride device is fabricated can be seen in Figure 11, where 110 is the step, 111 is the source (S) on the left side of the step, and 112 is on the right side of the step The drain (D) on the side, 113 is the gate (G) across the step, and 114 is the oxide layer deposited on the side wall of the step (that is, the side wall).

At this time, the sidewall is located between the gate metal of the GaN device and the conductive channel, and since the sidewall is made of an electrically insulating material, current can be prevented from passing through. It can be seen that the sidewall effectively isolates the gate metal and the conductive channel of the GaN device, and avoids the gate leakage of the GaN device.

Still referring to FIG. 11, the gallium nitride device provided by the present invention includes:

steps 110;

source level (S) 111 located on the left side of the step;

Drain stage (D) 112 located on the right side of the step;

a gate (G) 113 across the step;

The oxide layer 114 deposited on the sidewall of the step, that is, the sidewall, is made of an electrically insulating material.

Preferably, the oxide layer is made of silicon dioxide or silicon nitride.

Further, the thickness of the oxide layer is slightly smaller or not smaller than the thickness of the step.

In summary, the beneficial effects of the present invention include:

As shown in FIG. 6 , at this time, a layer of oxide layer, that is, a sidewall, is formed on the sidewall of the step of the GaN device. After the sidewall is added, the angle between the oxide layer on the sidewall of the step (that is, the sidewall) and the surface of the GaN device is much larger than 90°. As shown in Figure 7, when etching the metal layer deposited on the surface of the gallium nitride device, the metal layer on the front and back sides of the step can be completely removed, avoiding the metal layer on the front and back sides of the step in metal etching. The sidewall metal remains, and then the metal layer on the left and right sides of the step is used as the source of the gallium nitride device, and the metal layer on the other side is used as the drain of the gallium nitride device. As shown in FIG. 8 , 80 is the left side of the step, 81 is the right side of the step, 82 is the front side of the step, and 83 is the rear side of the step. After the sidewall is added, the short-circuit interconnection between the source and the drain of the GaN device can be effectively prevented. FIG. 9 is a schematic diagram of the morphology of a gallium nitride device after etching.

And, as shown in Figure 10, after adding the spacer, the gate metal and the conductive channel of the GaN device can be effectively isolated, thereby protecting the conductive channel of the GaN device and preventing the GaN device from Leakage.

Figure 11 is a schematic diagram of the structure of the gallium nitride device after the source, drain and gate are fabricated, where 110 is the step, 111 is the source (S) on the left side of the step, and 112 is the drain on the right side of the step The electrode (D), 113 is the grid (G) across the step, and 114 is the oxide layer deposited on the side wall of the step (that is, the side wall).

Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these modifications and variations.

Claims (8)

1. a kind of processing method of gallium nitride device, it is characterised in that this method includes：

Layer of oxide layer is accumulated in the surface cushion of the gallium nitride device so that the oxygen on the side wall of the step of the gallium nitride device Change the angle between layer and the surface of the gallium nitride device and be more than 90 °, the material of the oxide layer is electric insulation material；

The oxide layer is performed etching, the oxide layer on the wall of side to retain the step of the gallium nitride device is simultaneously got rid of The oxide layer of other parts outside the side wall of the step.

2. the method as described in claim 1, it is characterised in that performed etching to the oxide layer, to retain the nitridation Oxide layer on the side wall of the step of gallium device and get rid of other parts outside the side wall of the step oxide layer it Afterwards, further comprise：

In the surface cushion product layer of metal layer of the gallium nitride device；

The metal level is performed etching, with the metal level for the left and right sides for retaining the step and the step is got rid of The metal level of front and rear sides, using the metal level of side in the left and right sides of the step as the gallium nitride device source electrode, The metal level of opposite side as the gallium nitride device drain electrode.

3. method as claimed in claim 2, it is characterised in that performed etching to the metal level, to retain the step The left and right sides metal level, and after removing the metal level of front and rear sides of the step, further comprise：

Pad long-pending layer of metal layer again on the surface of the gallium nitride device；

The metal level for padding long-pending again is performed etching, to retain the metal level across the step and remove the gold at other positions Belong to layer, the metal level that would span across the step is used as the grid of the gallium nitride device.

4. the method as described in claim 1-3 is any, it is characterised in that the material of the oxide layer is silica.

5. the method as described in claim 1-3 is any, it is characterised in that the thickness of the oxide layer is not less than the step Thickness.

6. a kind of gallium nitride device, it is characterised in that the gallium nitride device includes step, is located at the left and right of the step respectively The source S and drain D and the grid G across the step of both sides；And,

Product is padded on the side wall of the step oxide layer so that oxide layer on the side wall of the step of the gallium nitride device with Angle between the surface of the gallium nitride device is more than 90 °, and the material of the oxide layer is electric insulation material.

7. gallium nitride device as claimed in claim 6, it is characterised in that the oxide layer for silica.

8. gallium nitride device as claimed in claims 6 or 7, it is characterised in that the thickness of the oxide layer is not less than described The thickness of rank.