Method and apparatus for increasing the saturation drain-source current of a packaged enhanced gallium nitride power device

Abstract

The application discloses a method and device for improving the saturation drain-source current of an encapsulated enhanced gallium nitride power device, characterized by irradiating the encapsulated enhanced P-type cap layer gallium nitride power device with gamma rays, controlling the energy of the gamma rays to be 1.25 MeV, the dose rate to be 10-50 rad(Si) / s, and the total dose to be 600-800 krad(Si), so that positive charge defects are introduced into the P-type cap layer of the enhanced gallium nitride power device, the effective doping of the channel is improved, and the saturation drain-source current of the encapsulated enhanced gallium nitride power device is increased; the method has the advantages of solving the current situation that the parameters of the enhanced P-type cap layer gallium nitride power device cannot be optimized after encapsulation, being mature and stable in technology, causing little environmental pollution, not needing to add other chemical substances during the irradiation process, and being low in cost.

Description

Technical Field

[0001] This invention relates to the field of nuclear radiation effects in integrated circuits, and more particularly to a method and apparatus for improving the saturated drain-source current of a packaged enhancement-mode gallium nitride power device. Background Technology

[0002] Gallium nitride (GaN) power devices, representing third-generation semiconductor devices, possess numerous advantages such as a large critical electric field, small size, high electron density, high efficiency, and high frequency, perfectly meeting the stringent requirements of power supply systems. The advantages of GaN power devices are based on their highly mobile two-dimensional electron gas (2DEG) structure. Due to the lattice mismatch between AlGaN and GaN, stress is generated at the interface. Under the combined effects of piezoelectric polarization and spontaneous polarization, a large number of electrons are generated near the GaN layer interface, known as a two-dimensional electron gas (2DEG). In the undoped state, the 2DEG density can reach 10-1. 13 cm -2 The magnitude is significant. Therefore, gallium nitride (GaN) power devices are inherently depletion-mode devices, but enhancement-mode devices can remain off even when the gate is de-energized, making them more energy-efficient and reliable. Currently, four main methods are used to achieve enhancement-mode in GaN power devices: P-type cap layer, fluorine ion implantation, recessed gate structure, and Cascode structure. Because P-type cap layer technology is repeatable and can fully utilize the advantages of GaN materials, it is suitable for large-scale industrial production.

[0003] However, with the continuous shrinking of process dimensions, very large-scale integrated circuits (VLSI) have placed new demands on power supply parameters. For example, the core voltage of CPUs, digital signal processing (DSPs), and field-programmable gate arrays (FPGAs) drops sharply, while power consumption current increases dramatically, requiring enhancement-mode gallium nitride (GaN) power devices, as power output stages, to output as large an operating current as possible. However, the optimization of GaN power device parameters is generally completed during the manufacturing process, such as changing the doping, thickness, and Al composition of the AlGaN barrier layer. After the enhancement-mode P-type cap GaN power device is packaged, its device parameters cannot be optimized, especially the saturation drain-source current parameter cannot be increased. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a method and apparatus for improving the saturation drain-source current of a packaged enhancement-type P-type cap gallium nitride power device.

[0005] The technical solution adopted by the present invention to solve the above-mentioned technical problems is as follows: a method for improving the saturated drain-source current of a packaged enhancement-type gallium nitride power device, wherein the packaged enhancement-type P-type cap layer gallium nitride power device is irradiated with gamma rays, and the energy of the gamma rays is controlled to be 1.25 MeV, the dose rate is 10-50 rad(Si) / s, and the total dose is 600-800 krad(Si), so as to introduce positive charge defects in the P-type cap layer of the enhancement-type gallium nitride power device, improve the effective doping of the channel, and thus increase the saturated drain-source current of the packaged enhancement-type gallium nitride power device.

[0006] Furthermore, the gamma ray irradiation source is a cobalt source.

[0007] Furthermore, the dose rate of gamma rays was controlled at 50 rad(Si) / s, and the total dose was 800 krad(Si).

[0008] The apparatus used to implement the method includes a mobile cart, an irradiation chamber, a detection system, a first robotic arm, a second robotic arm, and a third robotic arm. The mobile cart is equipped with a weight sensor. The first robotic arm is used to pick up and place the enhanced gallium nitride (GaN) power device to be irradiated into the mobile cart. The mobile cart is used to deliver the power device into the irradiation chamber for gamma irradiation and then deliver it out of the irradiation chamber. The irradiation chamber is equipped with a cobalt source. The second robotic arm is used to pick up the irradiated power device from the mobile cart and place it into the detection system. The third robotic arm is used to pick up the detected power device from the detection system and place it into the qualified or unqualified product area.

[0009] Compared with the prior art, the advantages of this invention are that by using gamma rays to irradiate the packaged enhancement-type P-type cap gallium nitride power device, the saturation drain-source current of the packaged gallium nitride power device is improved, which solves the current situation that the device parameters of the enhancement-type P-type cap gallium nitride power device cannot be optimized after packaging. Moreover, the method is technically mature and stable, with little environmental pollution, and no other chemical substances need to be added during the irradiation process, resulting in low cost. Attached Figure Description

[0010] Figure 1 This is a comparison of the output characteristic curves of the packaged enhanced gallium nitride power device of the present invention before and after irradiation.

[0011] Figure 2 This is a schematic diagram of the device of the present invention. Detailed Implementation

[0012] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0013] Example 1: A method for increasing the saturation drain-source current of packaged enhancement-mode gallium nitride power devices, using a cobalt source. 60 Co-γ was used as the irradiation source to irradiate the packaged enhancement-type P-type cap layer gallium nitride power device with gamma rays. The energy of the gamma rays was controlled to be 1.25 MeV, the dose rate was 50 rad(Si) / s, and the total dose was 800 krad(Si). This introduced positive charge defects into the P-type cap layer of the enhancement-type gallium nitride power device, increased the effective doping of B in the channel, and thus increased the saturation drain-source current of the packaged enhancement-type gallium nitride power device.

[0014] like Figure 1 As shown, the saturation drain-source current of the enhanced P-type capped gallium nitride power device increases significantly after irradiation, indicating that the method is effective for enhanced P-type capped gallium nitride power devices. This is because total dose irradiation introduces positively charged defects in the P-type capped layer, thereby increasing the effective doping of B in the channel, which macroscopically manifests as an increase in the saturation drain-source current.

[0015] In the above embodiment one, according to the actual requirements of the enhanced P-type cap layer gallium nitride power device, the dose rate of gamma rays during irradiation can be selected in the range of 10 to 50 rad(Si) / s, and the total dose can be selected in the range of 600 to 800 krad(Si).

[0016] Example 2: Figure 2 As shown, the apparatus used to implement the above method includes a mobile cart 1, an irradiation chamber 2, a detection system 3, a first robotic arm 4, a second robotic arm 5, and a third robotic arm 6. The mobile cart 1 is equipped with a weight sensor (not shown in the figure). The first robotic arm 4 is used to pick up and place the enhanced gallium nitride power device to be irradiated into the mobile cart 1. The mobile cart 1 is used to send the power device into the irradiation chamber 2 for gamma irradiation and send it out of the irradiation chamber 2. The irradiation chamber 2 is equipped with a cobalt source 10. The second robotic arm 5 is used to pick up and place the irradiated power device from the mobile cart 1 into the detection system 3. The third robotic arm 6 is used to pick up and place the detected power device from the detection system 3 into the qualified product area or the unqualified product area.

[0017] The specific working process of the device is as follows: The first robotic arm 4 picks up the enhanced gallium nitride (GaN) power device to be irradiated from the first sample box 7 and places it into the carrying box of the mobile cart 1. When the weight sensor in the mobile cart 1 detects that the weight of the power device in the carrying box has reached the set weight, the mobile cart 1 quickly moves to the cart stop position P in the irradiation chamber 2. This stop position is 50 rad (Si) / s dose point position from the source position. When the mobile cart 1 moves to the stop position, timing begins. When the total dose accumulates to 800 krad (Si), the mobile cart 1 quickly moves out of the irradiation chamber 2 to the end position. Then, the second robotic arm 5 picks up the irradiated power device from the mobile cart 1 and places it into the detection system 3 for testing. If the detected saturation drain-source current of the power device reaches the specified value, the third robotic arm 6 picks up the power device from the detection system 3 and places it into the second sample box 8; otherwise, it is placed into the third sample box 9. When the weight sensor in the mobile cart 1 detects that the weight in the carrying box is 0, the mobile cart 1 returns to the initial position, and the process is repeated. Irradiating power devices with this device not only ensures the safety of irradiation workers, but also enables fully automated batch processing of power devices, reducing the time required for source raising and lowering, and allowing the irradiation source to remain in a raised state.

[0018] The scope of protection of this invention includes, but is not limited to, the above embodiments. The scope of protection is defined by the claims. Any substitutions, modifications, or improvements to this technology that are easily conceived by those skilled in the art fall within the scope of protection of this invention.

Claims

1. A method of increasing the saturated drain-source current of a packaged enhancement mode gallium nitride power device, characterized by The encapsulated enhanced P-type cap layer gallium nitride power device is irradiated by gamma rays, the energy of the gamma rays is 1.25 MeV, the dose rate is 10-50 rad(Si) / s, and the total dose is 600-800 krad(Si), so that the positive charge defects are introduced into the P-type cap layer of the enhanced gallium nitride power device, the effective doping of the channel is improved, and the saturated drain-source current of the encapsulated enhanced gallium nitride power device is increased.

2. The method of increasing the saturated drain-source current of a packaged enhancement mode gallium nitride power device of claim 1, wherein: The irradiation source of the gamma rays is a cobalt source.

3. The method for increasing the saturation drain-source current of a packaged enhancement-mode gallium nitride power device as described in claim 1, characterized in that: The dose rate of the gamma rays is controlled to be 50 rad(Si) / s, and the total dose is 800 krad(Si).

4. Apparatus for carrying out the method of claim 1, characterized in that The system comprises a moving trolley, an irradiation chamber, a detection system, a first mechanical arm, a second mechanical arm and a third mechanical arm, the moving trolley is internally provided with a weight sensor, the first mechanical arm is used for taking and placing the enhanced gallium nitride power device to be irradiated into the moving trolley, the moving trolley is used for sending the power device into the irradiation chamber for irradiation by gamma rays and sending the power device out of the irradiation chamber, the irradiation chamber is internally provided with a cobalt source, the second mechanical arm is used for taking and placing the irradiated power device from the moving trolley into the detection system, and the third mechanical arm is used for taking and placing the detected power device from the detection system to a qualified product place or an unqualified product place.

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