A fan-out packaging method for gallium arsenide radio frequency chips based on resin

Abstract

The present invention belongs to the technical field of integrated circuit packaging, and particularly relates to a fan-out packaging method for gallium arsenide radio frequency chips based on a resin base. The method comprises the following steps: using a temporary bonding carrier as a carrier; coating a photodecomposed temporary bonding adhesive on the carrier by spin coating and curing, and then using a metal protective layer to protect the temporary bonding adhesive on the front side; bonding the back sides of two heterogeneous gallium arsenide radio frequency chips to the front side of the metal protective layer through an adhesive layer; using a wafer-level plastic packaging process to plastic-package and encapsulate two heterogeneous gallium arsenide radio frequency chips to form a first plastic packaging layer; performing laser or mechanical drilling on the first plastic packaging layer to expose the metal protective layer to form a first plastic packaging through hole; and filling in the first plastic packaging through hole to form a filler. The present invention reduces the chip manufacturing cost and realizes the miniaturization of the chip size. At the same time, the high heat dissipation conductive layer on the back side can effectively enhance the heat dissipation of the chip and improve the performance of the system.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuit packaging, and in particular relates to a resin-based gallium arsenide radio frequency chip fan-out packaging method. Background Art

[0002] Driven by the trend of small, light and thin electronic products, semiconductor integrated circuits need to continuously develop new packaging types: especially in the field of RF signals, there are more stringent requirements for packaging, which must meet various RF performance indicators, such as input / output impedance, isolation between ports, etc. Since the RF chips used in the RF transceiver front end are mostly based on compound semiconductor technology, in order to protect the active surface inductor and capacitor air bridge from damage and meet the back grounding requirements, the interconnection form of gallium arsenide chips is limited to wire bonding. However, as the operating frequency increases, the parasitic effect of the bonding wire cannot be ignored. Compared with wire bonding, flip-chip interconnection has a shorter signal transmission path and better realizes the miniaturization requirements of RF systems.

[0003] However, the key problem of the RF microwave chip flip-chip interconnect packaging in the existing technology lies in its back-metal grounding problem; secondly, with the improvement of integration, the heat dissipation of the active chip increases, and an efficient and simple thermal management method is urgently needed to improve the heat dissipation effect of the packaging module. Summary of the invention

[0004] The purpose of the present invention is to provide a fan-out packaging method for gallium arsenide radio frequency chips based on a resin substrate. The present invention changes the back-metal grounding method of the radio frequency chip, and leads the ground signal end of the active surface of the radio frequency chip to the back as a reference ground through the high heat dissipation conductive metal layer and the plastic sealing through hole on the back of the resin, thereby reducing the chip manufacturing cost and realizing the miniaturization of the chip size. At the same time, the high heat dissipation conductive layer on the back can effectively enhance the heat dissipation of the chip and improve the performance of the system.

[0005] In order to solve the above technical problems, the present invention provides a resin-based gallium arsenide radio frequency chip fan-out packaging method, comprising the following steps:

[0006] Step 1: Use a temporary bonding carrier as a carrier;

[0007] Step 2: Spin coating the photodegradable temporary bonding glue on the carrier and solidify it, and then use a metal protective layer to protect the temporary bonding glue on the front side;

[0008] Step 3: Bond the back sides of the two heterogeneous GaAs RF chips to the front side of the metal protective layer through an adhesive layer;

[0009] Step 4: Using a wafer-level plastic packaging process to plastic-package and encapsulate the two heterogeneous GaAs RF chips to form a first plastic packaging layer;

[0010] Step 5: Perform laser or mechanical drilling on the first plastic sealing layer to expose the metal protective layer to form a first plastic sealing through hole;

[0011] Step 6: Filling the first plastic package through hole to form a filling;

[0012] Step 7: Thin the front side of the first plastic encapsulation layer by grinding until the active surface pads of the two heterogeneous GaAs RF chips are exposed;

[0013] Step 8: completing a rewiring process on the front side of the first plastic packaging layer to form a metal rewiring layer;

[0014] Step 9: Use laser debonding process to carbonize temporary bonding glue and remove the carrier;

[0015] Step 10: Use a cleaning solution to further remove the residual temporary bonding glue;

[0016] Step 11: Use etching solution to remove the metal protective layer;

[0017] Step 12: coating a high heat dissipation conductive material on the back of the first plastic packaging layer to form a high heat dissipation conductive layer;

[0018] Step 13: Using a wafer-level ball implantation process, the required package solder balls are arranged on the metal rewiring layer of the plastic-encapsulated wafer to form the required integrated package, and thinning and dicing are performed as required to form a single package;

[0019] The heterogeneous gallium arsenide RF chip includes a chip back gold ground plane located on the back side, and the chip back gold ground plane is connected to the first plastic packaging through hole through the conductive adhesive layer and the high heat dissipation conductive layer.

[0020] Preferably, in step 1, the temporary bonding carrier is a glass wafer or a silicon wafer, the thickness of which is 400 μm to 1200 μm, and the size of which is 8 inches or 12 inches.

[0021] Preferably, in step 2, the thickness of the temporary bonding glue is not less than 0.1um, the curing temperature after coating is 300°C~400°C, and the curing time is 0.5h~3h; the material of the metal protective layer is Cu, Ti, Au or Ag, and its thickness is 0.1μm~0.3μm.

[0022] Preferably, in step 3, the bonding layer is conductive glue, metal solder or other conductive and bonding materials.

[0023] Preferably, in step 4, the molding material of the first molding layer includes polymers including resins and polyimides.

[0024] Preferably, in step 5, the first plastic sealing layer is etched by a laser etching process to form a first plastic sealing through hole.

[0025] Preferably, in step 6, electroplating copper is filled in the first plastic package through hole by an electroplating process, and the first plastic package through hole forms an electrical connection structure with the metal redistribution layer and the metal protection layer respectively through the electroplating copper.

[0026] Preferably, in step 8, the metal rewiring layer is 2 to 7 layers with a thickness of 1 μm to 8 μm, wherein the wiring structure at the outermost layer further includes a metal pad, wherein the wiring structure at the outermost layer further includes a metal pad.

[0027] Preferably, in step 12, the material of the high heat dissipation conductive layer is a mixture of resin and nano-metal material; wherein the resin is a highly thermosetting epoxy resin, and the nano-metal material is a mixture of nano-silver paste and nano-copper paste.

[0028] The present invention also provides a resin-based gallium arsenide radio frequency chip fan-out packaging structure, which is manufactured using the resin-based gallium arsenide radio frequency chip fan-out packaging method as described above.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention is achieved by coating a photodegradable temporary bonding glue on the top of the carrier, setting a metal protective layer on the surface of the temporary bonding glue, mounting a gallium arsenide radio frequency chip on the metal protective layer, and using a resin material for plastic sealing on the front. A vertical through hole is set in the plastic sealing layer, and a metallization layer is set in the through hole to form a conductive through hole, and the ground terminal of the radio frequency chip is led out and the connection between the wiring layers is realized through the conductive through hole. The resin material on the front side is thinned to expose the vertical interconnection structure and the active surface pad of the chip, and the wiring layer and the metal pad are prepared on the thinned front side. The photodegradable temporary bonding glue and the metal protective layer of the carrier are removed, and a layer of high heat dissipation conductive material is coated on the back of the plastic sealing wafer, and finally the ball is implanted on the metal pad on the front side. The present invention changes the metal reference grounding method on the back of the radio frequency chip by proposing a signal lead-out method on the back of the radio frequency chip. At the same time, the high heat dissipation conductive layer set on the back of the chip has both resin and metal characteristics, has certain reliability and high heat dissipation, and helps to quickly cool down the inside of the package to avoid heat accumulation and chip damage.

[0031] 2. The present invention solves the warping problem of the reconstructed wafer and improves product reliability by bonding the wafer and the reconstructed wafer together; by changing the back gold grounding method of the RF chip, the processing difficulty is reduced, the chip production cost is saved, and the chip size is miniaturized.

[0032] 3. The product structure of the present invention can meet the high heat dissipation requirements of high-power chips and improve the heat dissipation performance of the package. At the same time, the present invention does not use expensive silicon adapter plates and silicon through vias, further reducing the packaging cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 Schematic diagram of temporarily bonding a carrier in the method of the present invention.

[0034] Figure 2 It is a schematic diagram of coating a temporary bonding adhesive and a metal protective layer in the method of the present invention.

[0035] Figure 3 The figure is a schematic diagram of completing the mounting of two heterogeneous gallium arsenide radio frequency chips in the method of the present invention.

[0036] Figure 4 It is a schematic diagram of completing plastic sealing in the method of the present invention.

[0037] Figure 5 It is a schematic diagram of completing the production of plastic-sealed through holes in the method of the present invention.

[0038] Figure 6 It is a schematic diagram of completing the thinning of the plastic cover in the method of the present invention.

[0039] Figure 7 It is a schematic diagram of completing the rewiring layer and the passivation layer in the method of the present invention.

[0040] Figure 8 It is a schematic diagram of removing the temporary bonding carrier in the method of the present invention.

[0041] Fig. 9 Schematic diagram of removing residual temporary bonding adhesive in the method of the present invention.

[0042] Fig.10 It is a schematic diagram of removing the metal protective layer in the method of the present invention.

[0043] Fig.11 It is a schematic diagram of coating a highly heat-dissipating conductive material in the method of the present invention.

[0044] Fig.12 It is a schematic diagram after ball implantation is completed in the method of the present invention.

[0045] In the figure: 101-wafer, 102-temporary bonding glue, 103-metal protection layer, 104-gallium arsenide chip, 105-active surface pad, 106-adhesive layer, 107-first plastic packaging layer, 108-first plastic packaging through hole, 109-electroplated metal, 110-passivation layer, 111-metal rewiring layer, 112-metal pad, 113-high heat dissipation conductive layer, 114-package body solder ball. DETAILED DESCRIPTION

[0046] The present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the accompanying drawings are in very simplified form and in non-precise proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0047] like Figure 1 to Figure 12 As shown, the embodiment of the present invention specifically provides a resin-based gallium arsenide radio frequency chip fan-out packaging method, comprising the following steps:

[0048] (1) Using wafer 101 as a carrier, i.e., a temporary bonding carrier, such as Figure 1 As shown; the temporary bonding carrier is a glass wafer or a silicon wafer, the thickness of the carrier body is not less than 300μm, specifically 400μm to 1200μm, and the size of the carrier body is 8 inches or 12 inches.

[0049] (2) Spin coating the photodegradable temporary bonding adhesive 102 on the wafer 101 in step (1), such as Figure 2 As shown; the thickness of the temporary bonding glue 102 is not less than 0.1um, specifically 0.1μm~2μm, and is cured after the coating is completed, the curing temperature is 300℃~400℃, and the curing time is 0.5h~3h. A metal protective layer 103 is used to protect the front temporary bonding glue 102 to prevent the temporary bonding glue 102 from being corroded by the chemical solution in the wet process. The material of the above-mentioned metal protective layer is Cu, Ti, Au or Ag, and the thickness of the metal protective layer 103 is 0.1μm~0.3μm.

[0050] (3) Providing a heterogeneous gallium arsenide (GaAs) chip 104, bonding an adhesive layer 106 to the back of the heterogeneous GaAs chip 104, and horizontally mounting the heterogeneous GaAs chip 104 on the wafer in step (2) using a wafer mounter, such as Figure 3 As shown; the above-mentioned bonding layer is conductive glue, metal solder or other materials that can play a conductive and bonding role.

[0051] (4) The heterogeneous GaAs chip 104 is encapsulated and coated with a wafer-level encapsulation process to form a first encapsulation layer 107, such as Figure 4 As shown; the above-mentioned plastic packaging materials are polymers including resins and polyimides.

[0052] (5) Perform laser or mechanical drilling on the first plastic sealing layer 107 to expose the metal protective layer and form a first plastic sealing through hole 108, such as Figure 5 As shown; preferably, the first plastic sealing layer 107 can be etched by laser etching process to form the first plastic sealing through hole 108.

[0053] (6) Fill the blind first plastic-encapsulated through hole 108 by electroplating metal 109, such as Figure 5 As shown; preferably, an electroplating process can be used to fill the first plastic package through hole with electroplated copper, and the first plastic package through hole 108 structure is electrically connected to the metal rewiring layer 111 and the metal protective layer 103 through the electroplated copper.

[0054] (7) The first plastic encapsulation layer 107 is thinned on the front side by grinding until the active surface pad 105 of the heterogeneous GaAs chip is exposed, as shown in FIG. Figure 6 As shown;

[0055] (8) The rewiring process is completed on the wafer in step (7), the thickness of the passivation layer 110 is 2 μm to 10 μm, the thickness of the metal rewiring layer 111 is 1 μm to 8 μm, and the number of layers of the metal rewiring layer 111 is multiple, wherein the outermost wiring layer may also include a metal pad 112; preferably 2 to 7 layers, and the metal pad 112 may be manufactured as required, such as Figure 7 As shown;

[0056] (9) Carbonizing the temporary bonding adhesive 102 using a laser debonding process and removing the wafer 101, such as Figure 8 shown.

[0057] (10) After step (9), a cleaning solution is used to further remove the residual temporary bonding adhesive 102, such as Fig. 9 shown.

[0058] (11) After step (10), the metal protective layer 103 is removed using an etching solution, such as Fig.10 shown.

[0059] (12) After step (11), a layer of high heat dissipation conductive material is coated on the back of the plastic-encapsulated wafer to form a high heat dissipation conductive layer 113, such as Fig.11As shown; the material of the high heat dissipation conductive layer 113 is preferably a mixture of resin material and nano-metal material, wherein the resin is a thermosetting epoxy resin, and the nano-metal material is a mixture of nano-silver paste and nano-copper paste. Since the above-mentioned thermosetting epoxy resin has excellent physical properties and good chemical stability, it can ensure high reliability of isolation from the outside air. At the same time, the nanoparticles in the nano-silver paste and the nano-copper paste have extremely high specific surface area, which makes the transmission of electrons between particles more efficient, thereby significantly improving the conductivity of the material. The nano-silver paste and the nano-copper paste have high thermal conductivity and can effectively conduct heat away from the heat source to improve the heat conduction efficiency. Therefore, the combination of thermosetting epoxy resin and nano-metal material integrates the advantages of the two, which not only ensures the strength and stability of the material, but also improves the conductivity and heat dissipation. The above-mentioned heterogeneous gallium arsenide radio frequency chip includes a chip back gold grounding surface located on the back, and the connection between the gallium arsenide radio frequency chip back gold grounding surface and the first plastic sealing through hole 108 structure is realized through the conductive adhesive layer 106 and the high heat dissipation conductive layer 113.

[0060] (13) Using the wafer-level ball implantation process, the required package solder balls 114 are arranged on the metal pads 112 of the plastic-encapsulated wafer to form the required integrated package, and thinning and dicing are performed as required to form a single package, such as Fig.12 shown.

[0061] The above description is only a description of the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Any changes or modifications made by a person skilled in the art in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A resin-based gallium arsenide radio frequency chip fan-out packaging method, characterized in that: The steps include: Step 1: Use a temporary bonding carrier as a carrier; Step 2: Spin coating the photodegradable temporary bonding glue on the carrier and solidify it, and then use a metal protective layer to protect the temporary bonding glue on the front side; Step 3: Bond the back sides of the two heterogeneous GaAs RF chips to the front side of the metal protective layer through an adhesive layer; Step 4: Using a wafer-level plastic packaging process to plastic-package and encapsulate the two heterogeneous GaAs RF chips to form a first plastic packaging layer; Step 5: Perform laser or mechanical drilling on the first plastic sealing layer to expose the metal protective layer to form a first plastic sealing through hole; Step 6: Filling the first plastic package through hole to form a filling; Step 7: Thin the front side of the first plastic encapsulation layer by grinding until the active surface pads of the two heterogeneous GaAs RF chips are exposed; Step 8: completing a rewiring process on the front side of the first plastic packaging layer to form a metal rewiring layer; Step 9: Use laser debonding process to carbonize temporary bonding glue and remove the carrier; Step 10: Use a cleaning solution to further remove the residual temporary bonding glue; Step 11: Use etching solution to remove the metal protective layer; Step 12: coating a high heat dissipation conductive material on the back of the first plastic packaging layer to form a high heat dissipation conductive layer; Step 13: Using a wafer-level ball implantation process, the required package solder balls are arranged on the metal rewiring layer of the plastic-encapsulated wafer to form the required integrated package, and thinning and dicing are performed as required to form a single package; The heterogeneous GaAs RF chip includes a chip back gold ground plane located on the back, and the chip back gold ground plane is connected to the first plastic sealing through hole through the conductive adhesive layer and the high heat dissipation conductive layer; In the step 6, electroplating copper is filled in the first plastic-encapsulated through hole by an electroplating process, and the first plastic-encapsulated through hole forms an electrical connection structure with the metal redistribution layer and the metal protective layer respectively through the electroplating copper; In the step 12, the material of the high heat dissipation conductive layer is a mixture of resin and nano-metal material; wherein the resin is a highly thermosetting epoxy resin, and the nano-metal material is a mixture of nano-silver paste and nano-copper paste.

2. A resin-based gallium arsenide radio frequency chip fan-out packaging method as claimed in claim 1, characterized in that: In the step 1, the temporary bonding carrier is a glass wafer or a silicon wafer, the thickness of which is 400 μm to 1200 μm, and the size of which is 8 inches or 12 inches.

3. A resin-based gallium arsenide radio frequency chip fan-out packaging method as claimed in claim 1, characterized in that: In step 2, the thickness of the temporary bonding glue is not less than 0.1um, the curing temperature after coating is 300℃~400℃, and the curing time is 0.5h~3h; the material of the metal protective layer is Cu, Ti, Au or Ag, and its thickness is 0.1μm~0.3μm.

4. The resin-based gallium arsenide radio frequency chip fan-out packaging method according to claim 1, characterized in that: In step 3, the bonding layer is conductive glue or metal solder.

5. The resin-based gallium arsenide radio frequency chip fan-out packaging method according to claim 1, characterized in that: In the step 4, the molding material of the first molding layer includes polymers including resins and polyimides.

6. A resin-based gallium arsenide radio frequency chip fan-out packaging method as claimed in claim 1, characterized in that: In the step 5, the first plastic sealing layer is etched by a laser etching process to form a first plastic sealing through hole.

7. The resin-based gallium arsenide radio frequency chip fan-out packaging method according to claim 1, characterized in that: In step 8, the metal rewiring layer has 2 to 7 layers, and its thickness is 1 μm to 8 μm, wherein the wiring structure at the outermost layer also includes a metal pad.

8. A resin-based gallium arsenide radio frequency chip fan-out packaging structure, characterized in that: The fan-out packaging method of gallium arsenide radio frequency chip based on a resin substrate is used to manufacture the fan-out packaging method.

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