Panel-level fan-out type packaging structure and method for silicon-based GaN HEMT device
Technical Field
The invention relates to the technical field of wafer-level packaging, in particular to a panel-level fan-out type packaging structure and a packaging method of a silicon-based GaN HEMT device.
Background
The electronic product can convert electric energy into heat energy when working due to the internal resistance of the electronic product, so that the temperature of the whole machine is increased, and when the heat generation speed is equal to the dissipation speed, the heat balance state is achieved, and the temperature is stabilized at a determined value. The resistance is generally in positive correlation with the temperature, the internal resistance of the device is increased along with the increase of the temperature, so that the consumed electric energy is also increased, the efficiency of the whole machine is reduced, and the energy is wasted. For this reason, it is expected that the lower the temperature at which the device operates stably, the better, and the higher the dissipation rate of heating becomes.
In power supply products, for example charger, adapter, fill electric pile, data center power etc. inside switching device is the main source of thermogenesis, so solve the heat dissipation that switching device is favorable to improving power supply product's efficiency. The traditional switch device mainly uses a silicon (Si) -based MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor), and the Si-based MOSFET cannot meet the application of high frequency and high power due to the limitation of materials and structures. The third generation semiconductor material device GaN High Electron Mobility Transistor (GaN HEMT) has the characteristics of High breakdown field strength, High Electron Mobility, High junction temperature and the like, and is an ideal device for replacing a Si MOSFET.
The difference between the thermal conductivity of the GaN material and the thermal conductivity of Si is not large, and the packaging thermal resistance is required to be small enough for exerting the excellent performance of the GaN HEMT.
When the MOSFET is in operation, when the Gate (Gate) voltage is greater than the threshold voltage Vth, carriers flow from the Source (Source) to the Drain (Drain) through the Gate to form a path, and the on and off of the device are controlled by controlling the Gate voltage, and meanwhile, the switching loss and the conduction loss are accompanied in a channel. The Source and Drain of the GaN HEMT device are both on the surface of the device, heat is mainly concentrated on the surface of the device, the Source and Drain of the traditional Si MOSFET are respectively located on the surface and the bottom of the device and belong to a vertical structure, and heat generated during working penetrates through the whole device. This results in GaN HEMTs with package heat treatment requirements that are different from those of conventional Si devices.
The traditional packaging of the Si-based power device adopts a Wire Bonding process, the chip mainly depends on a Frame (Lead Frame) at the bottom of the chip for heat dissipation when working, the heat dissipation mode is single, and the slender Wire brings larger parasitic inductance, so that the high-frequency application of the product is limited.
Wafer Level Packaging (WLP) was introduced in about 2000. Until now, most packaging processes have been mechanical processes such as grinding, sawing, wire bonding, and the like.
Fanout technology can be divided into three main types: chip-first/face-down, chip-first/face-up, and chip-last. These basic structures have expanded to include many variations, with variations appearing, it is increasingly difficult for end users to understand the differences between them, as well as their respective advantages and disadvantages. Each supplier of the fan-out has its own set of architecture, with different material combinations and process flows, and terminology to distinguish itself. This makes it a significant challenge for the end user to not only select the packaging architecture, but also to be able to provide a second source for any defined architecture. This may negatively impact the high volume implementation.
There are several challenges in the near future for Wafer level packaging technologies such as Wafer level CSP. With the development of silicon technology nodes, reliability and Chip Package Interaction (CPI) face greater challenges as the WLCSP size increases. This is not only the reliability performance, but also an adverse effect that may occur in subsequent processes after fabrication of the WLCSP. This includes transportation and handling, and final assembly onto a circuit board. There is increasing interest in adding five-sided or six-sided protection in the form of mold type compounds around WLCSP to provide additional protection for the post-fabrication process. At present, 5 surfaces of a Wafer of Wafer level CSP are exposed in the air, and the Wafer cannot meet high-voltage and complex application environments in various aspects of structural strength, safety specification, reliability and the like of products.
Disclosure of Invention
The invention aims to provide a panel-level fan-out packaging structure of a silicon-based GaNHEMT device, which is designed by utilizing a plate electrode fan-out packaging technology and combining a wide bandgap semiconductor device and has the advantages of high heat dissipation capacity, high reliability and low parasitic inductance.
In order to achieve the purpose, the technical scheme of the invention is as follows:
a panel-level fan-out type packaging structure of a silicon-based GaN HEMT device comprises a silicon-based GaN HEMT chip 1, wherein the periphery and the front of the silicon-based GaN HEMT chip are wrapped by a first plastic packaging material 41, the front of the silicon-based GaN HEMT chip is the upper surface of a GaN device layer 12 on a silicon substrate 11, the bottom of the silicon substrate 11 is the back of the chip, the bottom of the silicon-based GaN HEMT chip is directly connected with a bottom metal layer 7, the upper surface of the silicon-based GaN HEMT chip 1 is an insulating layer 6, an input and output port 5 is arranged on the insulating layer 6 through punching, the upper surface of the insulating layer 6 is a copper circuit 3, pins are arranged above the copper circuit 3, the copper circuit 3 leads out the input and output ports of the chip, and adjacent copper circuits 3 are isolated through a second plastic packaging material 42; the bottom metal layer 7 below the silicon-based GaN HEMT chip 1 is a first heat dissipation channel, and the copper circuit 3 above the input/output port 5 on the front surface of the silicon-based GaN HEMT chip 1 is a second heat dissipation channel.
As a preferred mode, the silicon-based gan hemt device panel-level fan-out package structure is obtained by the following packaging method:
(1) the insulating layer 6 is adhered to the surface of the GaN wafer 8; (ii) a
(2) Exposing the input/output port 5 by laser drilling on the insulating layer 6;
(3) cutting the GaN wafer 8 into single silicon-based GaN HEMT chips 1 and then inversely installing the single silicon-based GaN HEMT chips on a carrier plate;
(4) the periphery of the silicon-based GaN HEMT chip 1 and the back surface of the chip are plastically packaged by a first plastic package material 41,
(5) grinding and thinning the first plastic packaging material 41 on the back surface of the chip until the Si substrate 11 on the back surface is exposed, and stripping;
(6) a copper circuit 3 is wired on the front surface of a silicon-based GaN HEMT chip 1 by an exposure and development method, an input/output port 5 of the GaN chip is led out to the surface of a product by electroplating, and a pin 2 is formed;
(7) forming a bottom metal layer 7 on the back of the silicon-based GaN HEMT chip in an electroplating and sputtering mode, and enhancing heat dissipation through the bottom metal layer 7;
(8) and the front surface of the silicon-based GaN HEMT chip is plastically packaged by using a second plastic packaging material 42.
In order to achieve the above object, the present invention further provides a method for packaging a panel-level fan-out package structure of a silicon-based GaN HEMT device, comprising the following steps:
(1) the insulating layer 6 is adhered to the surface of the GaN wafer 8; (ii) a
(2) Exposing the input/output port 5 by laser drilling on the insulating layer 6;
(3) cutting the GaN wafer 8 into single silicon-based GaN HEMT chips 1 and then inversely installing the single silicon-based GaN HEMT chips on a carrier plate;
(4) the periphery of the silicon-based GaN HEMT chip 1 and the back surface of the chip are plastically packaged by a first plastic package material 41,
(5) grinding and thinning the first plastic packaging material 41 on the back surface of the chip until the Si substrate on the back surface is exposed, and stripping;
(6) a copper circuit 3 is wired on the front surface of the silicon-based GaN HEMT chip by an exposure and development method, an input/output port 5 of the GaN chip is led out to the surface of a product by electroplating, and a pin 2 is formed;
(7) a bottom metal layer 7 is formed on the back of the silicon-based GaN HEMT chip in an electroplating and sputtering mode, and heat dissipation is enhanced through the bottom metal layer 7.
(8) And the front surface of the silicon-based GaN HEMT chip is plastically packaged by using a second plastic packaging material 42.
The invention has the beneficial effects that:
compared with the traditional bonding wire packaging process in which a gold wire/copper wire is used for leading out the input/output port, the invention greatly reduces the parasitic resistance and inductance caused by packaging, and further improves the upper limit of the application frequency of the product.
The back of the chip is directly connected with the metal radiating fin, and another radiating channel is provided except the bottom of the chip, so that the packaging thermal resistance is greatly reduced, and the problem of difficult radiation of the front of the GaN HEMT is solved. Forming double heat dissipation channels.
Drawings
Fig. 1 is a schematic view of a panel-level fan-out package structure of a silicon-based GaN HEMT device according to an embodiment of the present invention;
fig. 2-8 are schematic diagrams illustrating steps of a packaging method according to an embodiment of the present invention.
The chip comprises a substrate 1, a substrate 11, a GaN device layer 12, pins 2, copper lines 3, a first plastic package material 41, a second plastic package material 42, an input/output port 5, an insulating layer 6, a bottom metal layer 7 and a GaN wafer 8.
Detailed Description
As shown in fig. 1, the embodiment provides a panel-level fan-out package structure of a silicon-based GaN HEMT device, including a silicon-based GaN HEMT chip 1, where the periphery and front of the silicon-based GaN HEMT chip 1 are wrapped by a first molding compound 41, the front of the silicon-based GaN HEMT chip 1 is the upper surface of a GaN device layer 12 on a silicon substrate 11, the bottom of the silicon substrate 11 is the back of the chip, the bottom of the silicon-based GaN HEMT chip is directly connected to a bottom metal layer 7, the upper surface of the silicon-based GaN HEMT chip 1 is an insulating layer 6, an input/output port 5 is formed in the insulating layer 6 by punching, the upper surface of the insulating layer 6 is a copper line 3, a pin 2 is arranged above the copper line 3, the copper line 3 leads out the input/output port of the chip, and adjacent copper lines 3 are isolated by a second molding compound 42; the bottom metal layer 7 below the silicon-based GaN HEMT chip 1 is a first heat dissipation channel, and the copper circuit 3 above the input/output port 5 on the front surface of the silicon-based GaN HEMT chip 1 is a second heat dissipation channel.
The embodiment also provides a packaging method of the panel-level fan-out packaging structure of the silicon-based GaN HEMT device, which comprises the following steps:
(1) as shown in fig. 2, the insulating layer 6 is adhered to the surface of the GaN wafer 8;
(2) as shown in fig. 3, the input/output port 5 is exposed by laser drilling the insulating layer 6;
(3) as shown in fig. 4, the GaN wafer 8 is cut into single silicon-based GaN HEMT chips 1 and then flip-chip mounted on a carrier board;
(4) as shown in fig. 5, the periphery of the silicon-based GaN HEMT chip 1 and the back surface of the chip are plastically packaged by a first plastic package material 41,
(5) as shown in fig. 6, the first molding compound 41 on the back surface of the thinned chip is ground until the Si substrate on the back surface is exposed, and the board is removed;
(6) as shown in fig. 7, a copper circuit 3 is wired on the front surface of the silicon-based GaN HEMT chip by an exposure and development method, an input/output port 5 of the GaN chip is led out to the surface of a product by electroplating, and a pin 2 is formed;
(7) as shown in fig. 8, a bottom metal layer 7 is formed on the back surface of the silicon-based GaN HEMT chip by means of electroplating and sputtering, and heat dissipation is enhanced by the bottom metal layer 7;
(8) and the front surface of the silicon-based GaN HEMT chip is plastically packaged by using a second plastic packaging material 42.
While the present invention has been particularly shown and described with reference to the preferred embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.