A PIN diode employing an arc-shaped graded junction

Abstract

The application discloses a PIN diode with an arc-shaped gradually-changing tube core, which comprises a substrate and a diode packaging structure, wherein the diode packaging structure is arranged on the substrate; the diode packaging structure comprises a first anode metal plate, an anode air bridge, a tube core, a cathode metal plate and an N-type high-doped layer; the first anode metal plate is connected with a second anode metal through the anode air bridge; the tube core comprises the second anode metal, a P-type high-doped layer and a semiconductor I layer; the second anode metal plate is in contact with the P-type high-doped layer to form an anode ohmic contact electrode; the cathode metal plate is in contact with the N-type high-doped layer to form a cathode ohmic contact electrode; the P-type high-doped layer is arranged directly below the second anode metal plate; and the semiconductor I layer is arranged between the P-type high-doped layer and the N-type high-doped layer. The application can eliminate the electric field concentration effect and improve the maximum withstand power of the diode by adjusting the gradually-changing shape.

Description

Technical Field

[0001] This invention relates to PIN diodes, and more particularly to a PIN diode employing an arc-shaped tapered die. Background Technology

[0002] PIN diodes, as important microwave and millimeter-wave control devices, possess advantages such as high controllable power, low loss, high speed, and excellent open-circuit and short-circuit characteristics. Therefore, they are widely used in phase shifters, modulators, limiters, attenuators, switches, and various microwave and millimeter-wave control circuits, offering irreplaceable advantages in high-voltage, high-power, and high-speed applications. As a solid-state semiconductor device, a PIN diode consists of a P-layer composed of heavily doped P-type material, an N-layer composed of heavily doped N-type material, and an I-layer composed of a lightly doped intrinsic layer with high resistivity. The presence of the I-layer causes the PIN diode to exhibit high resistance at zero bias, increasing impedance under reverse bias, and exhibiting a voltage-controlled low resistance characteristic under forward bias. Under zero-bias high microwave power loading, the PIN diode also exhibits a low resistance characteristic that decreases with increasing microwave power. The microwave impedance characteristics of the PIN diode depend only on the DC bias characteristic or the magnitude of the microwave power, making it highly suitable for use as a microwave and millimeter-wave control device. In these microwave control circuits that use PIN diodes, the PIN diodes, as the most basic switching element, directly determine the upper limit of the control circuit's performance.

[0003] With the development of microwave and millimeter-wave control circuits towards higher frequencies, higher power, and miniaturization, higher requirements are being placed on the material doping, packaging structure, reliability, and performance indicators of PIN diodes. To meet the increasingly demanding requirements of microwave and millimeter-wave circuits, the development and production of new high-power PIN diodes through process design, structural design, and material design is of great significance. Changing the material and thickness of the I-region can improve the operating frequency and performance of PIN diodes, but the involved processes are complex and costly. Optimizing the packaging structure to improve the heat dissipation, power capacity, and reliability of PIN diodes is a more effective method, such as optimizing the cross-sectional area of ​​the die (I-region) and the distance between the anode and cathode. In existing reports, the die cross-section of PIN diodes is mostly designed with rectangular, circular, or elliptical shapes with uniformly varying characteristics, and the distance between the anode and cathode is constant. Under high power loading, the electric field intensity in the die of PIN diodes with uniform cross-sections cannot be uniformly distributed due to the distribution characteristics of the on-resistance and the concentration characteristics of the electric field. The power that the diode can withstand is determined by the point of strongest electric field. This phenomenon is more obvious at high frequencies, which limits the improvement of PIN diode performance and operating frequency. Summary of the Invention

[0004] Purpose of the invention: The purpose of this invention is to provide a PIN diode with an arc-shaped gradient die that can improve maximum power tolerance and burn-out resistance.

[0005] Technical Solution: The PIN diode of the present invention includes a substrate and a diode packaging structure, wherein the diode packaging structure is disposed on the substrate; the diode packaging structure includes a first anode metal plate, an anode air bridge, a die, a cathode metal plate, and an N-type highly doped layer; the first anode metal plate is connected to a second anode metal plate through the anode air bridge; the die includes a second anode metal plate, a P-type highly doped layer, and a semiconductor I layer; the second anode metal plate is in contact with the P-type highly doped layer to form an anode ohmic contact electrode; the cathode metal plate is in contact with the N-type highly doped layer to form a cathode ohmic contact electrode; the P-type highly doped layer is disposed directly below the second anode metal plate, and the semiconductor I layer is disposed between the P-type highly doped layer and the N-type highly doped layer; the cross-sectional shape of the second anode metal plate is gradually widening, with arcs at both ends having different radii; the smaller cross-sectional end of the second anode metal plate is connected to the anode air bridge, and the larger cross-sectional end is disposed within the arc-shaped opening of the cathode metal plate, with the width gradually increasing from the smaller cross-sectional end to the larger cross-sectional end;

[0006] The cross-sectional shapes of the P-type highly doped layer and the semiconductor I layer are the same as those of the second anode metal plate. The second anode metal, the P-type highly doped layer, and the semiconductor I layer are arranged together from top to bottom to form the die.

[0007] Furthermore, the first anode metal plate is formed by electron beam evaporation deposition and has a structure with unequal widths at both ends, with the transition portion being an angled structure; the electron beam is made of Ti, Pt, Au, or a Ti / Pt / Au alloy.

[0008] Furthermore, the cathode metal plate is formed by electron beam evaporation deposition, and the electron beam is made of Ti, Pt, Au, or a Ti / Pt / Au alloy; the cross-sectional shape is "U-shaped", the radius of the "U-shaped" is larger than the arc radius of the large cross-section end of the second anode metal plate, and the end face of the straight edge of the "U-shaped" has no sharp corners; the straight edge of the cathode metal plate surrounds the die.

[0009] Furthermore, the substrate is a dielectric substrate made of semiconductor material.

[0010] Furthermore, the material of the second anode metal plate is Ti, Pt, Au, or a Ti / Pt / Au alloy.

[0011] A multi-die PIN diode includes a substrate and at least two of the aforementioned diode package structures, wherein the diode package structures are connected in series.

[0012] A lateral die PIN diode, wherein the gradient direction of the die cross-section structure described in any of the above claims is perpendicular to the direction of the electric field entering the diode.

[0013] Compared with the prior art, the significant advantages of this invention are as follows:

[0014] 1. The present invention adopts a gradient die structure, which makes the distributed on-resistance of the die gradually distributed, eliminating the electric field accumulation effect, and improving the power withstand capability of the diode by rationally arranging the electric field distribution through the gradual change of on-resistance.

[0015] 2. This invention adopts a gradient die structure, which changes the distance between the anode and the cathode, so that the conduction resistance of the die changes gradually. By controlling the type of gradient line, the electric field distribution is controlled, the diode's operating characteristics are improved, and the operating bandwidth of a single PIN diode is effectively increased.

[0016] 3. The die of the present invention adopts an arc-shaped gradient structure, which increases the cross-sectional area through which the transient current flows under high power loading of the PIN diode, improves the heat dissipation capacity of the die, and improves the burn-out resistance of the PIN diode. Attached Figure Description

[0017] Figure 1(a) is a top view of the overall structure of the present invention.

[0018] Figure 1(b) is a cross-sectional view of AA in Figure 1(a);

[0019] Figure 2(a) shows a comparison of the electric field simulation of a uniform die PIN diode.

[0020] Figure 2(b) Comparison of electric field simulation of graded-die PIN diode;

[0021] Figure 3 A schematic diagram of a series PIN diode using an arc-shaped tapered die;

[0022] Figure 4 This is a schematic diagram of a lateral die PIN diode using an arc-shaped gradient die. Detailed Implementation

[0023] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0024] Figure 1(a) shows the PIN diode of the present invention, including a substrate and a diode packaging structure above the substrate. Figure 1(b) shows the diode packaging structure including a first anode metal 1, an anode air bridge 2, a die, a cathode metal 4, and an N-type highly doped layer 7. The die includes a second anode metal plate 3, a P-type highly doped layer 5, and a semiconductor I layer 6. The diode packaging structure is disposed on a substrate 8. The first anode metal 1 is formed by electron beam evaporation deposition of Ti / Pt / Au, and is connected to the second anode metal plate 3 via the anode air bridge 2, serving as the connection metal between the PIN diode anode and the outside world. The first anode metal plate 1 has unequal widths at both ends, with a chamfered transition portion in the middle to reduce the parasitic parameters of the PIN diode. The arc-shaped anode air bridge 2 is made of Ti, Pt, Au, or a Ti / Pt / Au (titanium / platinum / gold) alloy, connecting the first anode metal plate 1 and the third anode metal plate 3, serving as the signal connection channel between the anode and the outside world. The second anode metal plate 1 has unequal widths at both ends, and the middle transition portion is chamfered to reduce the parasitic parameters of the PIN diode. The arc-shaped anode air bridge 2 is made of Ti, Pt, Au, or a Ti / Pt / Au (titanium / platinum / gold) alloy, connecting the first anode metal plate 1 and the third anode metal plate 3, serving as the signal connection channel between the anode and the outside world. The anode metal plate 3 is made of Ti, Pt, Au, or a Ti / Pt / Au alloy and contacts the P-type highly doped layer 5, forming the anode ohmic contact electrode of the PIN diode. The second anode metal plate 3 has a gradient cross-section with arc-shaped structures of different radii at both ends, gradually increasing in size from the connection end with the first anode metal plate 1. The cathode metal plate 4 is formed by electron beam evaporation deposition of Ti, Pt, Au, or a Ti / Pt / Au alloy and contacts the N-type highly doped layer 7, forming the cathode ohmic contact electrode of the PIN diode. The cross-sectional shape of the cathode metal plate 4 is... The "U-shape" has a radius slightly larger than the arc radius of the large cross-section end of the second anode metal plate (3); the two straight edges of the cathode metal plate 4 surround the anode, and the edges of the straight edges are chamfered to eliminate the accumulation of spike charges; the P-type highly doped layer 5 is located directly below the second anode metal plate 3 and is the P layer of the PIN diode, which accumulates a large number of holes; the semiconductor I layer 6 is located directly below the P-type highly doped layer 5 and is the intrinsic layer of the PIN diode, located between the P layer and the N layer, forming the main characteristics of the PIN diode; the N-type highly doped layer 7 is located directly below the semiconductor I layer 6. The P-layer of the PIN diode gathers a large number of electrons. The substrate 8 is made of semiconductor materials (GaAs, InP, GaN, Si, etc.) and supports the PIN diode. In integrated circuits, it is also the dielectric substrate of the circuit. The cross-sectional shape of the P-type highly doped layer 5 and the lightly doped semiconductor I-layer 6 is consistent with that of the second anode metal plate 3. The three are arranged vertically and together form the die of the PIN diode. The PIN diode adopts a half-mesa structure. The N-type highly doped layer 7 extends outward and contacts the cathode metal plate 4 to form a cathode ohmic contact, which makes the PIN diode easy to integrate.

[0025] I. Arc-shaped Gradient Core Cross-section Structure

[0026] In this invention, the second anode metal plate 3, the P-type highly doped layer 5, and the semiconductor I layer 6 constituting the PIN diode die all adopt an arc-shaped gradient structure. In the PIN diode, the anode and cathode metal plates 4 form a current path through the N-type highly doped layer 7. Under forward bias or high-power loading, a distributed on-resistance is formed, the magnitude of which is positively correlated with the distance between the two (anode and cathode metal plates). When the die cross-sectional shape gradually changes, the distance between the anode and cathode metal plates 4 gradually changes, causing the on-resistance of the PIN diode to gradually change. This change in on-resistance affects the electric field distribution applied to the PIN diode. By controlling the electric field distribution through the shape of the gradient line, the electric field distribution on the PIN diode becomes more uniform, and the area with the highest power withstand capability of the die bears a greater electric field, effectively improving the diode's maximum power withstand capability.

[0027] The electric field distribution of PIN diodes with different die structures under high power loading was simulated. The electric field distribution on the PIN diodes is shown in Figure 2(a) and Figure 2(b). It can be seen that the electric field distribution of the PIN diode with a uniform die structure has obvious aggregation characteristics, while the electric field distribution of the PIN diode with a gradient die structure is more uniform, thus achieving control over the electric field distribution.

[0028] In addition, under high power loading, the conduction current in the PIN diode exhibits a clustering effect (i.e., the current concentrates at the edge of the anode). The heat dissipation capacity of the PIN diode is positively correlated with the size of the cross-sectional area through which the current flows. In this invention, an arc-shaped anode cross-section structure is adopted, which increases the cross-sectional area through which the transient current of the PIN diode flows, improves the heat dissipation capacity of the die, and improves the PIN's resistance to burnout.

[0029] In summary, this invention improves the maximum power handling capacity and burn-out resistance of diodes by employing an arc-shaped gradient die cross-section structure.

[0030] II. Diode Structure Extension

[0031] The above example is merely one embodiment of the present invention. All diodes constructed using the gradient die structure mentioned in this invention, whether single-die or multi-die series-parallel PIN diodes, are within the protection scope of this invention. Furthermore, this invention also provides examples of PIN diodes with two dies connected in series, such as... Figure 3 And PIN diodes with a lateral die layout, such as Figure 4 As shown. Among them, as Figure 4In PIN diodes employing a lateral die, compared to conventional layouts, the gradient direction of the die anode cross-section structure is perpendicular to the direction of the electric field entering the diode (the straight line connecting the centers of the small and large cross-section ends is perpendicular to the direction of the electric field). The first anode metal is connected to the centerline of the second anode metal via an anode air bridge; therefore, the widths of the first anode metal 1 and the anode air bridge 2 are relatively wide. Similarly, multi-die diodes constructed using PIN diodes with a lateral die layout are also within the scope of this invention.

Claims

1. A PIN diode employing an arc-shaped gradient die, characterized in that, The device includes a substrate and a diode packaging structure, wherein the diode packaging structure is disposed on the substrate; the diode packaging structure includes a first anode metal plate (1), an anode air bridge (2), a die, a cathode metal plate (4), and an N-type highly doped layer (7), wherein the first anode metal plate (1) is connected to a second anode metal plate (3) through the anode air bridge (2); the die includes a second anode metal plate (3), a P-type highly doped layer (5), and a semiconductor I layer (6), wherein the second anode metal plate (3) is in contact with the P-type highly doped layer (5) to form an anode ohmic contact electrode; the cathode metal plate (4) is a first anode metal plate (1), an anode air bridge (2), a die, a cathode metal plate (4), and an N-type highly doped layer (7). The anode metal plate (4) is in contact with the N-type highly doped layer (7) to form a cathode ohmic contact electrode; the P-type highly doped layer (5) is located directly below the second anode metal plate (3), and the semiconductor I layer (6) is located between the P-type highly doped layer (5) and the N-type highly doped layer (7); the cross-sectional shape of the second anode metal plate (3) is gradually widening and has arcs with different radii at both ends. The small cross-sectional end of the second anode metal plate (3) is connected to the anode air bridge (2), and the large cross-sectional end is located in the arc-shaped opening of the cathode metal plate (4). The width gradually increases from the small cross-sectional end to the large cross-sectional end. The cross-sectional shapes of the P-type highly doped layer (5) and the semiconductor I layer (6) are the same as those of the second anode metal plate (3). The second anode metal plate (3), the P-type highly doped layer (5) and the semiconductor I layer (6) are arranged together from top to bottom to form a die.

2. The PIN diode with an arc-shaped gradient die according to claim 1, characterized in that, The first anode metal plate (1) is formed by electron beam evaporation deposition and has a structure with unequal widths at both ends and a beveled structure in the transition part; the electron beam is made of Ti or Pt or Au or Ti / Pt / Au alloy.

3. The PIN diode with an arc-shaped gradient die according to claim 1, characterized in that, The cathode metal plate (4) is formed by electron beam evaporation deposition. The electron beam is made of Ti, Pt, Au, or Ti / Pt / Au alloy. The cross-sectional shape is "U-shaped". The radius of the "U-shaped" is greater than the arc radius of the large cross-section end of the second anode metal plate (3). The end face of the straight edge of the "U-shaped" has no sharp corners. The straight edge of the cathode metal plate (4) surrounds the core.

4. The PIN diode with an arc-shaped gradient die according to claim 1, characterized in that, The substrate (8) is a dielectric substrate made of semiconductor material.

5. The PIN diode with an arc-shaped gradient die according to claim 1, characterized in that, The material of the second anode metal plate (3) is Ti or Pt or Au, or Ti / Pt / Au alloy.

6. A multi-chip PIN diode, characterized in that, It includes a substrate and at least two diode package structures as described in any one of claims 1-5, wherein the diode package structures are connected in series.

7. A lateral die PIN diode, characterized in that, The gradient direction of the die cross-section structure of the PIN diode with an arc-shaped gradient die as described in any one of claims 1, 2, 4, and 5 is perpendicular to the direction of the electric field entering the diode.

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