CN111383929B

CN111383929B - Wafer plastic packaging method, wafer level packaging structure, packaging method thereof and plastic packaging mold

Info

Publication number: CN111383929B
Application number: CN201811654671.4A
Authority: CN
Inventors: 石虎; 李海江; 敖萨仁; 李洪昌; 孙尧中
Original assignee: Ningbo Semiconductor International Corp
Current assignee: Ningbo Semiconductor International Corp
Priority date: 2018-12-28
Filing date: 2018-12-28
Publication date: 2022-03-11
Anticipated expiration: 2038-12-28
Also published as: CN111383929A

Abstract

The invention provides a wafer plastic package method, a wafer level package structure, a package method thereof and a plastic package mold.A wafer loaded with a plastic package material is placed on a first template of the plastic package mold, pressure is applied to the plastic package material through a second template of the plastic package mold so as to form a plastic package layer on the surface of the wafer deviating from the first template, wherein a bulge is formed on the surface of the second template of the plastic package mold facing the wafer, and when the second template applies pressure to the plastic package material, the bulge is positioned above a notch and is used for preventing the plastic package material from overflowing from the notch, so that the plastic package with a larger area can be realized, the eccentric problem of the plastic package is improved, the cutting area in the subsequent trimming process is reduced, and the utilization rate of effective chips on the wafer is improved.

Description

Wafer plastic packaging method, wafer level packaging structure, packaging method thereof and plastic packaging mold

Technical Field

The invention relates to the technical field of semiconductor packaging, in particular to a wafer plastic packaging method, a wafer level packaging structure, a packaging method and a plastic packaging mold.

Background

With the trend of very large scale integrated circuits, the feature size of the integrated circuits is continuously decreasing, and the requirements of people on the packaging technology of the integrated circuits are also increasing correspondingly. Conventional packaging technologies include System In Package (SIP), System On Chip (SOC) Package, Wafer Level Package (WLP), and the like. SIP is a package integration method that combines a plurality of active components, passive components, and optical components with different functions into a unit to form a system or subsystem that can provide multiple functions, and allows heterogeneous ICs to be integrated. Compared with SOC, the SIP technology is relatively simple, the design period and the market period are shorter, the cost is lower, and a more complex system can be realized. Compared with the traditional SIP, the WLP completes the packaging process on the wafer, has the advantages of greatly reducing the area of a packaging structure, reducing the manufacturing cost, optimizing the electrical performance, manufacturing in batches and the like, and can obviously reduce the workload and the requirement of equipment.

However, the chip utilization of the current wafer level packaging method needs to be further improved.

Disclosure of Invention

The invention provides a wafer plastic package method, a wafer level package structure, a packaging method and a plastic package mold, which are beneficial to improving the utilization rate of effective chips on a wafer.

The invention provides a wafer plastic package method, which comprises the following steps:

providing a wafer, wherein the edge of the wafer is provided with a notch;

adding a plastic packaging material on the wafer;

placing the wafer on a first template of a plastic package mold, and applying pressure to the plastic package material through a second template of the plastic package mold so as to form a plastic package layer on the surface of the wafer deviating from the first template;

and when the second template applies pressure to the plastic packaging material, the bulge is positioned above the notch and used for preventing the plastic packaging material from overflowing from the notch.

Optionally, in the wafer plastic package method, the protrusion is made of an elastic material, an original height of the protrusion is greater than a thickness of the plastic package layer, and the protrusion abuts against the notch of the wafer when the second template applies pressure to the plastic package material.

Optionally, in the wafer plastic package method, the notch is V-shaped, and the protrusion is a cylinder or a triangular prism structure with a V-shaped concave.

Optionally, in the wafer plastic package method, an area of a surface of the protrusion contacting the wafer is larger than an area of the notch.

Optionally, in the wafer plastic package method, the plastic package layer is an epoxy resin layer.

Optionally, in the wafer plastic package method, after a plastic package material is added to a surface of the wafer away from the first template, the plastic package material is heated.

Optionally, in the wafer plastic package method, the heating temperature of the plastic package material is 160 ℃ to 180 ℃.

Optionally, in the wafer plastic package method, a release film is attached to one surface of the second template facing the wafer.

Optionally, in the method for plastic packaging of a wafer, the wafer is bonded to a carrier through a chip connection film.

Optionally, in the wafer plastic package method, after a plastic package layer is formed on a surface of the wafer departing from the first template, demolding is performed, and the wafer after plastic package is baked.

The invention also provides a wafer-level chip packaging method, which comprises any one of the wafer plastic packaging methods.

Optionally, in the wafer-level chip packaging method, after baking the wafer, further comprising,

carrying out an edge cutting process on the wafer, and removing the plastic packaging layer positioned at the edge of the wafer; and the number of the first and second groups,

thinning or removing the carrier.

The invention also provides a wafer level chip packaging structure, comprising: the wafer comprises a central area and an edge area surrounding the central area, the edge area is provided with a notch, and the plastic packaging layer at least covers one part of the edge area.

Optionally, in the wafer-level chip package structure, the wafer is bonded to a carrier through a chip connection film, and the plastic package layer is formed on a surface of the wafer deviating from the carrier.

Optionally, in the wafer-level chip package structure, the carrier is a metal, silicon, glass, or organic substrate.

The invention also provides a plastic package mold, which is used for carrying out plastic package on a wafer and comprises a second template, a first template and an injection unit, wherein the first template is used for bearing the wafer, the injection unit is used for adding a plastic package material to the surface of the wafer, which is far away from the first template, the second template is used for applying pressure on the plastic package material, a bulge is formed on the surface, facing the wafer, of the second template of the plastic package mold, and when the second template applies pressure on the plastic package material, the bulge is positioned above the notch and is used for preventing the plastic package material from overflowing from the notch.

Optionally, in the plastic package mold, the protrusion is made of an elastic material, and the protrusion is bonded to the second mold plate of the plastic package mold through a glue.

Optionally, in the plastic package mold, before the protrusion is not in contact with the wafer, the thickness of the protrusion is greater than that of the plastic package layer

Optionally, in the plastic package mold, an area of a surface of the protrusion contacting the wafer is larger than an area of the notch.

Optionally, in the plastic package mold, the protrusion is a curved surface body or a polyhedron.

Optionally, in the plastic package mold, the protrusion includes: the wafer support comprises a protrusion main body and a buffer pad, wherein the protrusion main body is connected with the second template, and the buffer pad is located on one surface, facing the wafer, of the protrusion main body.

Optionally, in the plastic package mold, the protruding main body is made of the same material as the second template, and the protruding main body is integrally formed and connected with the second template, or the protruding main body is connected with the second template through welding.

Optionally, in the plastic package mold, the bump cushion is made of an elastic material, and the bump cushion is bonded to one surface of the bump main body facing the wafer through a glue, or the bump cushion is nested on the surface of the bump main body.

Optionally, in the plastic package mold, the protrusion main body is a curved body or a polyhedron.

Optionally, in the plastic package mold, an area of a surface of the bump cushion contacting the wafer is larger than an area of the notch.

Optionally, in the plastic package mold, the elastic material is a rubber material, and the glass transition temperature of the elastic material is higher than the plastic package temperature.

In summary, the present invention provides a wafer plastic package method, in which a wafer loaded with a plastic package material is placed on a first template of a plastic package mold, and a second template of the plastic package mold applies pressure to the plastic package material to form a plastic package layer on a surface of the wafer deviating from the first template, wherein a protrusion is formed on a surface of the second template of the plastic package mold facing the wafer, and the protrusion is located above the notch and used to prevent the plastic package material from overflowing from the notch when the second template applies pressure to the plastic package material, so that a larger area of plastic package can be realized, the plastic package eccentricity problem can be improved, the cutting area in a subsequent trimming process can be reduced, and the utilization rate of effective chips of the wafer can be improved.

Drawings

FIG. 1a is a schematic structural diagram of a wafer without eccentricity during plastic package in the prior art;

FIG. 1b is a schematic structural diagram of a wafer with eccentricity during plastic package in the prior art;

FIG. 1c is a cross-sectional view along the AA' direction of the wafer of FIG. 1a after being molded;

FIG. 1d is a cross-sectional view of the wafer of FIG. 1a after being molded along the direction BB';

fig. 2 is a flowchart of a wafer plastic packaging method according to an embodiment of the present invention;

fig. 3a is a schematic structural diagram of a wafer in step S01 in the wafer plastic packaging method according to the embodiment of the present invention;

FIG. 3b is a cross-sectional view of the wafer of FIG. 3a along direction AA';

FIG. 3c is a cross-sectional view of the wafer of FIG. 3a taken along direction BB';

fig. 4 is a cross-sectional view of the wafer disposed on the carrier along the AA' direction in step S01 in the method for plastic packaging of a wafer according to the embodiment of the present invention;

fig. 5 is a cross-sectional view along the AA' direction after a plastic package material is added to the surface of the wafer in step S02 in the wafer plastic package method according to the embodiment of the present invention;

fig. 6 is a cross-sectional view of the wafer mold package mold along the AA' direction in step S03 in the wafer mold package method according to the embodiment of the present invention;

fig. 7 is a cross-sectional view along the AA' direction after a molding layer is formed on the surface of the wafer in step S03 in the wafer molding method according to the embodiment of the present invention;

fig. 8a is a schematic structural diagram of a wafer after being demolded in step S03 in the wafer plastic packaging method according to the embodiment of the present invention;

FIG. 8b is a cross-sectional view along AA' of the wafer of FIG. 8a after being released;

FIG. 8c is a cross-sectional view of the wafer of FIG. 8a taken along direction BB' after demolding;

fig. 9 a-9 b are schematic structural views of a protrusion in a plastic package mold according to an embodiment of the present invention, where the protrusion in fig. 9a is a triangular prism, and the protrusion in fig. 9b is a V-shaped polyhedron;

fig. 10 a-10 b are schematic structural views of bumps in a plastic package mold according to another embodiment of the invention, in which fig. 10a shows that the bump main bodies are triangular prisms, the bump pads are bonded to the surfaces of the bump main bodies facing the wafer, and fig. 10b shows that the bump main bodies are triangular prisms, and the bump pads are nested on the surfaces of the bump main bodies.

Reference numerals:

10. 100-a wafer; 100 a-wafer center area; 100 b-wafer edge area 100 b; 11. 110-chip; 12. 120-notch; 130-a bump; 131-a convex body; 132-raised cushion; 15. 105-a plastic packaging layer; 16-an annular region; 101-a carrier; 102-a first template; 103-a second template; 104-plastic packaging material.

Detailed Description

As is well known, the edge region of the wafer usually has a Notch (Notch), which is generally V-shaped and can be used as a mark of the crystal orientation of the wafer and can be used for positioning during the wafer manufacturing process. The inventors found that in a Molding process of a Wafer Level Package (WLP), a Molding Compound (Molding Compound) on a Wafer is thermally pressed until the Wafer is close to the Wafer size, and the Molding Compound overflows from a V-shaped notch at the edge of the Wafer. Limited by the notch on the wafer, the area of the plastic packaging material covering the wafer (i.e. the plastic packaging area) is often smaller than the area of the wafer during actual plastic packaging, so as to avoid the problem of overflow of the plastic packaging material.

Fig. 1a is a schematic structural diagram of a wafer without eccentricity in plastic package in the prior art, fig. 1b is a schematic structural diagram of the wafer with eccentricity in the prior art, fig. 1c is a cross-sectional diagram of the wafer in fig. 1a along the direction AA 'after the wafer is plastic packaged, and fig. 1d is a cross-sectional diagram of the wafer in fig. 1a along the direction BB'.

As shown in fig. 1a to 1d, due to the V-shaped notch 12 at the Edge of the wafer 10, the molding layer 15 does not completely cover the wafer 10, that is, there is an annular region 16 at the Edge of the wafer 10 that is not molded, the annular region 16 that is not molded includes a plurality of active chips (Good Die)11, and the annular region 16 at the Edge of the wafer 10 needs to be removed in a subsequent Edge trimming (Edge trimming) process, so that the molding area is consistent with the area of the wafer 10 after trimming, which causes a phenomenon that the active chips 11 in the wafer 10 are wasted, and reduces the utilization rate of the active chips 11 of the wafer 10.

Ideally, as shown in fig. 1a, the center O' of the plastic-molded plastic layer 15 should coincide with the center O of the wafer 10. However, in the process of plastic encapsulation, the plastic encapsulation material has certain fluidity under the action of hot pressing, and the plastic encapsulation material is prevented from overflowing from the V-shaped notch 12 of the wafer 10, so that the center O' of the plastic encapsulation layer 15 subjected to plastic encapsulation molding does not coincide with the center O of the wafer 10, as shown in fig. 1b, that is, the plastic encapsulation is eccentric. In the subsequent trimming and wafer thinning process, the center O of the wafer 10 is used as the center of trimming and wafer thinning, but due to the fact that the center O' of the plastic package layer 15 deviates from the center O of the wafer 10, the edge of the wafer 10 is subjected to the phenomenon that the plastic-sealed area is removed by trimming, and the non-plastic-sealed area is reserved. Since the exposed part (non-plastic encapsulated area) still exists at the edge of the surface of the wafer 10 after trimming, the exposed part at the edge is very easy to break when the wafer is thinned later, and the effective chips at the edge of the wafer adjacent to the edge are affected.

In order to solve the above problems, the inventor has tried to adopt a scheme that, in the trimming process, the center O of the wafer 10 is used as the trimming center, and the minimum distance between the center O of the wafer and the edge of the plastic package layer 15 is used as the radius, the wafer 10 is trimmed to ensure that all the non-plastic package region on the wafer 10 is cut off, but the excessive trimming method cuts off a part of the effective chips 11 which are already plastic packaged on the wafer 10, so that the effective chips are damaged and wasted.

Based on the above research, embodiments of the present invention provide a wafer plastic package method, a wafer level package structure, a package method thereof, and a plastic package mold. In the wafer plastic package method, a wafer is placed on a first template of a plastic package mold, pressure is applied to a plastic package material through a second template of the plastic package mold, so that a plastic package layer is formed on the surface, deviating from the first template, of the wafer, a bulge is formed on the surface, facing the wafer, of the second template of the plastic package mold, and when the second template applies pressure to the plastic package material, the bulge is located above a notch and used for preventing the plastic package material from overflowing from the notch. According to the embodiment of the invention, the bulge is formed on the second template of the plastic package mold, so that the bulge can prevent the plastic package material from overflowing from the notch of the edge of the wafer in the plastic package process, further, the plastic package with a larger area can be realized, the plastic package eccentricity problem is improved, the cutting area in the subsequent trimming process is reduced, and the utilization rate of the effective chip of the wafer is increased.

In order to make the contents of the present invention more clearly understood, the contents of the present invention will be further described with reference to the accompanying drawings. The invention is of course not limited to this particular embodiment, and general alternatives known to those skilled in the art are also covered by the scope of the invention.

The present invention is described in detail with reference to the drawings, and for convenience of explanation, the drawings are not enlarged partially according to the general scale, and should not be construed as limiting the present invention.

Fig. 2 is a flowchart of a wafer molding method according to this embodiment, and as shown in fig. 2, the wafer molding method according to this embodiment includes the following steps:

s01: providing a wafer, wherein the edge of the wafer is provided with a notch;

s02: adding a plastic packaging material on the wafer; and the number of the first and second groups,

s03: placing the wafer on a first template of a plastic package mold, and applying pressure to the plastic package material through a second template of the plastic package mold to form a plastic package layer on the upper surface of the wafer; and when the second template applies pressure to the plastic packaging material, the bulge is positioned above the notch and used for preventing the plastic packaging material from overflowing from the notch.

Fig. 3a to 8c are schematic structural diagrams corresponding to corresponding steps of a wafer molding method according to this embodiment, and a detailed description will be given below of the wafer molding method according to this embodiment with reference to fig. 2 and fig. 3a to 8 c.

First, step S01 is executed, as shown in fig. 3a to 3c, a wafer 100 is provided, the edge of the wafer 100 has a Notch (Notch)120, the Notch 120 can be used as a mark of the wafer crystal direction, and can play a role of positioning in the IC manufacturing, processing, and transporting equipment. In this embodiment, the notch 120 is V-shaped and has a left boundary and a right boundary opposite to each other, a center line of the notch 120 coincides with a center of the wafer 100, and the left boundary and the right boundary of the notch 120 are symmetrical with respect to the center line of the notch 120. It is understood that the method is not limited to the shape and size of the notch, and the method provided in the present application can be applied to the notch of the wafer having other shapes (e.g., circular arc, etc.).

The Wafer 100 is, for example, a Device Wafer (CMOS Wafer) having a plurality of individual chips 110 formed thereon, such as a finished Device. The wafer 100 may be fabricated according to a corresponding layout design by using an integrated circuit fabrication technology, for example, forming devices such as NMOS and/or PMOS, an interconnection layer formed by a dielectric layer and a metal layer, and a pad on the interconnection layer on the wafer by performing operations such as thin film deposition, photolithography, etching, ion implantation, etc., so as to fabricate the individual chips 110 arranged in an array in the wafer. The chip 110 may be various types of chips, such as a memory chip, a communication chip, a processor chip, a MEMS chip, and the like. The individual chips 110 formed on the same wafer 100 may be the same function or different function chips, and their fabrication processes may be the same, similar, or completely different. Of course, the individual chips 110 formed on one wafer 100 are generally the same in function. Taking the independent chip 110 as an example of an MEMS chip, MEMS devices such as a gyroscope, an accelerometer, an inertial sensor, a pressure sensor, a flow sensor, a displacement sensor, an electric field intensity sensor, a current sensor, a magnetic flux sensor, a magnetic field intensity sensor, a temperature sensor, a heat flow sensor, a thermal conductivity sensor, an optical modulator, a sound sensor, a gas sensor, a humidity sensor, an ion sensor, and a biosensor can be fabricated on a semiconductor substrate (e.g., a silicon wafer) by using a MEMS chip fabrication process disclosed in the art, and after packaging is completed, independent chip grains can be separated to serve as a single MEMS chip. Illustratively, the material of the substrate selected for the wafer 100 may be at least one of the following materials: si, Ge, SiGe, SiC, SiGeC, InAs, GaAs, InP or other III/V compound semiconductors, and the substrate may be a multilayer structure of these semiconductor materials or the like, or silicon-on-insulator (SOI), silicon-on-insulator (SSOI), silicon-on-insulator-germanium (S-SiGeOI), silicon-on-insulator-germanium (SiGeOI), germanium-on-insulator (GeO), and the like, which are well known to those skilled in the art, and are not exemplified.

Next, step S02 is executed to add the molding compound 104 on the wafer 100.

Specifically, the wafer 100 may be bonded to a carrier 101 through a die attach film (DAF, not shown in fig. 4), and the carrier 101 may prevent the wafer 100 from cracking, warping, breaking, and the like during subsequent manufacturing processes. The carrier 101 may be a metal substrate, a silicon wafer, a glass substrate, an organic substrate, etc., the geometry of the carrier 101 may be regular (e.g., round, square) or irregular, and an appropriate carrier may be selected according to actual requirements.

Then, a molding compound 104 is added to a central region of the surface of the wafer 100 facing away from the carrier 101, where the molding compound 104 includes, but is not limited to, polyimide, silicone, epoxy resin, curable polymer material, or curable resin material, preferably epoxy resin, and can be softened or flowed during a molding process, have plasticity, can be formed into a certain shape, and simultaneously undergo a chemical reaction to be cross-linked and cured. The plastic package material 104 further includes a hardener, a filler, an additive, and the like, and the specific ratio of each component is the prior art and is not discussed here. In this embodiment, the molding compound 104 is a viscous liquid prepared by mixing epoxy resin, a curing agent, a filler, an additive, and the like, and is dropped onto a central area of the surface of the wafer 100 away from the first template 102 by an injection unit (e.g., a dropper), as shown in fig. 5.

Next, step S03 is executed to place the wafer 100 on a first mold plate 102 of a plastic mold, and apply pressure to the plastic molding material 104 through a second mold plate 103 of the plastic mold, so as to form a plastic molding layer 105 on the upper surface of the wafer 100. When the second mold plate applies pressure to the plastic package material 104, the protrusion 130 is located above the notch 120 and is used to prevent the plastic package material 104 from overflowing from the notch 120.

The mold assembly for molding a wafer in a plastic package in the present embodiment includes a first mold plate 102, a second mold plate 103, and an injection unit (not shown). The first mold plate 102 is used to support the wafer 100, and is usually located at a lower position during molding, which may also be referred to as a lower mold plate. The injection molding unit is used for adding a plastic molding material to the surface of the wafer 100 departing from the first template 102. The second mold plate 103 is used to apply pressure to the molding material, and is usually located at an upper position during molding, and may also be referred to as an upper mold plate. A protrusion 130 is formed on the surface of the second mold plate 103 of the plastic package mold facing the wafer 100, and the position of the protrusion 130 on the second mold plate 103 corresponds to the position of the notch 120 on the wafer 100.

The second template 103 is made of steel, and has better strength and heat conductivity. The protrusion 130 is preferably made of an elastic material, such as a high temperature resistant rubber-like material or other composite materials with elasticity, and the protrusion 130 maintains elasticity during the hot pressing process of the subsequent plastic packaging process, such as neoprene (CR), butyl rubber (IIR), silicone rubber (Q), etc.

The protrusion 130 may be fixed on the second mold plate 103 by an adhesive, for example, by gluing the two together by using a LOCTITE-40FL curing adhesive, a LOCTITE 480 quick drying adhesive and a thermal adhesive. It will be appreciated that the invention is not limited to the material and manner of attachment of the projections, and that the projections may be made of a non-resilient material or may be attached to the second template by other means than adhesive, for example, the second template and projections may be integrally formed.

The protrusion 130 may be a curved surface body or a polyhedron, for example, a triangular prism (shown in fig. 9 a), a V-shaped polyhedron (a cylinder with a V-shaped concave structure, shown in fig. 9 b), a cylinder, an arc cylinder, etc., an area of a surface of the protrusion 130 contacting with the wafer 100 is greater than or equal to an area of the notch 120, and a thickness (i.e., an original height of the protrusion) of the protrusion 130 protruding out of the second template 103 when no pressure is applied to the second template 103 is greater than a thickness of a subsequent plastic package layer formed on the upper surface of the wafer 100, and the protrusion 130 may contract and abut against the V-shaped notch 120 at the edge of the wafer 100 after the pressure is applied to the second template 103. The shape of the surface of the protrusion 130 contacting the wafer 100 may be square, triangular, polygonal, circular or irregular. In order to increase the plastic package area of the wafer 100, the shape of the protrusion 130 corresponds to the notch 120 of the wafer, and since the notch 120 is V-shaped, the protrusion 130 is preferably a triangular prism or a V-shaped polyhedron. Taking the protrusion 130 as a triangular prism structure as an example, one bottom surface of the triangular prism is fixed on the second template 103, and the other bottom surface is used for contacting the wafer 100 during plastic encapsulation (the bottom surface contacting the wafer 100 is triangular). Taking the protrusion 130 as a V-shaped polyhedron (a cylinder with a V-shaped concave) as an example, the section of the V-shaped polyhedron parallel to the direction of the second mold plate 103 is V-shaped, one bottom surface of the V-shaped polyhedron is fixed on the second mold plate 103, and the other bottom surface is used for contacting the wafer 100 during plastic encapsulation (the bottom surface contacting the wafer 100 is V-shaped).

In addition, in the specific implementation, a release film (not shown in fig. 5) may be attached to a surface of the second mold plate 103 facing the wafer 100, so as to facilitate demolding after plastic encapsulation. The release film may cover the portion of the second mold plate 103 where the protrusions 130 protrude from the second mold plate 103 at the same time, or may cover only the portion of the second mold plate 103 where no protrusions are formed.

The specific implementation steps are as follows: the wafer 100 with the surface added with the plastic packaging material 104 is placed on a first template 102 of a plastic packaging mold, and the circle center of the wafer 100 corresponds to the centers of the first template 102 and the second template 103, so that subsequent plastic packaging operation is facilitated. Meanwhile, the wafer 100 is located below the second template 103 of the plastic package mold, and a protrusion 130 is formed on the second template 103 of the plastic package mold, and the position of the protrusion 130 corresponds to the V-shaped notch 120 on the wafer 100. The material of the protrusion 130 is preferably an elastic material, and when no pressure is applied to the second mold plate 103, the thickness of the protrusion 130 protruding the second mold plate 103 (i.e., the original height of the protrusion 130) is greater than the thickness of the plastic package layer 105 formed on the upper surface of the wafer 100 in the following process, so that the protrusion 130 can contract to a certain thickness (the thickness of the plastic package layer 105) under the action of an external force and abut against the V-shaped notch 120 at the edge of the wafer 100, so that the plastic package material 104 on the wafer 100 does not overflow from the V-shaped notch 120 after being subjected to the hot pressing in the following plastic package process.

The molding compound 105 may be formed on the wafer 100 by heating the molding dies (the second mold plate 103 and the first mold plate 102) and applying pressure to the molding compound 104 through the second mold plate 103, wherein the molding compound 105 covers the wafer 100 except for the notch 120, as shown in fig. 7. The heating step of the plastic package mold and the step of applying pressure to the plastic package material 104 through the second mold plate 103 may be performed simultaneously, or the plastic package mold may be heated for a period of time (for example, 30 seconds to 180 seconds) to increase the flowability of the plastic package material 104, and then the second mold plate 103 applies pressure to the plastic package material 104. After the wafer 100 is placed in the plastic package mold, the plastic package machine station heats the plastic package material 104 by heating the plastic package mold (the second template 103 and the first template 102), and the heating temperature of the plastic package mold is 160-180 ℃. In this embodiment, the plastic package mold is made of steel, and has good thermal conductivity, and the heating temperature of the plastic package material 104 may be as high as 160 ℃ to 180 ℃, for example, 160 ℃, 170 ℃, or 180 ℃, so as to obtain a good heating effect. The molding compound 104 has low melt viscosity and good fluidity when heated, and a certain pressure is applied through the second mold plate 103, so that the molding compound 104 covers the surface of the wafer 100 and forms a molding layer 105. During the hot pressing process, the protrusion 130 is located above the wafer gap 120 to prevent the hot-pressed molding compound 104 from overflowing from the wafer gap 120. By way of example, the thickness of the finally formed molding layer 105 may be 20 μm to 100 μm, for example, 50 μm, 70 μm, or 90 μm.

When the second mold plate 103 applies pressure to the plastic package material 104, the second mold plate 103 is in contact with the plastic package material 104, and the protrusion 130 is compressed to abut against the notch 120 at the edge of the wafer 100. Specifically, if the protrusion 130 is a triangular prism structure, as shown in fig. 9a, when the second template 103 applies pressure to the plastic package material 104, the protrusion 130 is located above the notch 120, an area of a surface (a bottom surface of the triangular prism) of the protrusion 130 contacting the wafer 100 is larger than an area of the notch 120, that is, the protrusion 130 covers the notch 120 and abuts against the wafer 100 at an edge of the notch 120 to completely prevent the plastic package material 104 from overflowing from the notch 120. If the protrusion 130 is a V-shaped polyhedron (a polyhedron structure with a V-shaped concave), as shown in fig. 9b, when the second mold plate 103 applies pressure to the plastic package material 104, the protrusion 130 abuts against the wafer 100 at the edge of the V-shaped notch 120, that is, the protrusion 130 blocks the edge of the notch 120, so as to prevent the plastic package material 104 from flowing into the notch 120.

After the plastic package material 104 is thermally pressed and cured on the surface of the wafer 100 to form the plastic package layer 105, demolding may be performed to separate the first template 102 and the second template 103, and the protrusion 130 on the second template 103 is completely separated from the plastic package layer 105. After demolding, the molded wafer 100 is transferred to a baking bracket in a molding machine for baking to completely cure the molding material 104, wherein the baking temperature is 80-250 ℃, for example, 150 ℃, 180 ℃, 210 ℃, and the like.

Fig. 8a is a schematic structural diagram of a wafer after being molded according to an embodiment of the invention, fig. 8b is a cross-sectional view of the wafer along direction AA 'after being demolded in fig. 8a, and fig. 8c is a cross-sectional view of the wafer along direction BB' after being demolded in fig. 8 a. As shown in fig. 8a to 8c, the molding layer 105 covers the area except the edge notch 120 of the wafer 100. That is, in the embodiment, the protrusion 130 formed on the second template 103 of the plastic package mold can prevent the plastic package material 104 from overflowing from the notch 120 of the edge of the wafer during the plastic package process, so that the plastic package with a larger area can be realized, since the region except the notch 120 of the edge of the wafer 100 is basically plastic-packaged, the plastic package eccentricity problem is improved, and in the subsequent trimming process engineering, the trimming area is greatly reduced, so that the utilization rate of the effective chip of the wafer is improved.

It should be noted that, whether the wafer 100 is transferred to the first mold plate 102 of the plastic package mold after the plastic package material 104 is added, or the wafer is placed on the first mold plate 102 of the plastic package mold before the plastic package material 104 is added may be selected according to the specific setting and the actual process requirement of the plastic package machine, which is not limited in the embodiment of the present invention.

The embodiment of the invention also provides a wafer-level chip packaging method, which is used for carrying out plastic packaging on the wafer 100 by adopting the wafer plastic packaging method, carrying out Edge trimming (Edge trimming) on the wafer 100 and removing the plastic packaging layer 105 positioned at the Edge of the wafer 100.

Subsequently, the thickness of the carrier 101 may be reduced or the carrier 101 may be directly removed. Specifically, the carrier 101 may be thinned by a back grinding process, a wet etching process, or a hydrogen ion implantation process, and thinning the carrier 101 is advantageous for reducing the overall thickness of the integrated circuit device to be formed.

Finally, the metal redistribution layer (RDL) process and the ball mounting process are performed to complete the subsequent packaging process, and the specific process is the same as the existing process and is not discussed here.

As shown in fig. 8a to 8c, the wafer-level chip package structure provided by the embodiment of the present invention includes a wafer 100 and a molding layer 105 formed on the wafer 100, where the wafer 100 includes a central region 100a and an edge region 100b surrounding the central region 100a, the edge region 100b has a notch 120, and the molding layer 105 covers at least a portion of the edge region 100 b. For example, the molding layer 105 covers both the central region 100a and the edge region 100b of the wafer 100, as shown in fig. 8 a. Of course, in practical implementation, the molding layer 105 may cover only a portion of the edge area 100b, for example, the diameter of the molding layer 105 is smaller than the diameter of the wafer 100, or the diameter of the molding layer 105 is equal to the diameter of the wafer 100 but some of the wafers are exposed at positions around the notch 120 (i.e., the area around the notch 120 is not covered by the molding layer 105).

The wafer 100 may be disposed on a carrier 101, the carrier 101 is, for example, a metal, silicon, glass, or organic substrate, the wafer 100 may be bonded to the carrier 101 through a Die Attach Film (DAF), and the molding layer 105 is formed on a surface of the wafer 100 facing away from the carrier 101. The plastic packaging layer 105 is mainly made of epoxy resin, and the thickness of the plastic packaging layer 105 is 20-100 microns.

The embodiment of the present invention further provides a plastic package mold, which is used for performing plastic package on a wafer, as shown in fig. 5 to 7, the plastic package mold includes a second template 103, a first template 102 and an injection unit (not shown in the drawings), the first template 102 is used for bearing the wafer 100, the injection unit is used for adding a plastic package material 104 onto a surface of the wafer 100 away from the first template 102, the second template 103 is used for applying pressure to the plastic package material 104, a protrusion 130 is formed on a surface of the second template 103 of the plastic package mold facing the wafer 100, and when the second template 103 applies pressure to the plastic package material 104, the protrusion 130 is located above the wafer notch 120 and is used for preventing the plastic package material 104 from overflowing from the notch 120.

The protrusion 130 is made of an elastic material, and the protrusion 130 is adhered to the second mold plate 103 of the plastic package mold through a glue. The elastic material is, for example, a high temperature resistant rubber-like material, and the protrusions 130 maintain elasticity during the wafer molding process, especially during the hot pressing process.

The thickness of the protrusion 130 protruding from the second template 103 (i.e., the original height of the protrusion 130) when no pressure is applied to the second template 103 (before the protrusion 120 is in contact with the wafer 100) is greater than the thickness of the molding layer 105 formed on the upper surface of the wafer 100. The protrusion 130 is a curved body or a polyhedron, for example, a triangular prism, a V-shaped polyhedron, a cylinder, an arc cylinder, etc., and the shape of the surface of the protrusion 130 contacting the wafer 100 is a square, a triangle, a polygon, a circle, or an irregular shape. The area of the surface of the protrusion 130 contacting the wafer 100 is larger than the area of the notch 120. Preferably, the protrusions 130 in this embodiment may be triangular prisms or V-shaped polyhedrons, as shown in fig. 9a and 9 b. Thus, the shape of the surface of the protrusion 130 contacting the wafer 100 is triangular or V-shaped, and corresponds to the shape of the wafer notch 120, so as to increase the plastic package area of the wafer 100.

Specifically, as shown in fig. 9a, the protrusion 130 is a triangular prism, the second template 103 is right when the plastic package material 104 applies pressure, the protrusion 130 is located above the notch 120, one surface of the protrusion 130 contacting the wafer 100 is triangular, and the area of the triangle is larger than that of the notch 120, that is, the protrusion 130 covers the notch 120 and abuts against the wafer 100 at the edge of the notch 120, so as to prevent the plastic package material from overflowing from the notch 120. As shown in fig. 9b, the protrusion 130 is a V-shaped polyhedron (concave polyhedron), and when the second mold plate 103 applies pressure to the molding compound 104, the protrusion 130 is located above the V-shaped edge of the notch 120, that is, the protrusion 130 is located on the wafer 100 at the edge of the V-shaped notch 120, and partially surrounds the notch 120 at a side away from the opening of the notch 120, so as to block the molding compound 104 from flowing into the notch 120. Of course, the shape of the protrusion 130 may also be a hollow V-shaped polyhedron or a hollow arc cylinder to surround the notch 120 from the periphery. However, considering the size of the notch 120 on the edge of the wafer 100 and the manufacturing cost of the protrusion 130, the shape of the protrusion 130 is preferably triangular prism or cylinder.

In other embodiments of the present invention, the protrusion 130 includes: a protrusion body 131 and a buffer pad 132, wherein the protrusion body 131 is connected to the second mold plate 103, and the buffer pad 132 is located on a surface of the protrusion body 130 facing the wafer. The protrusion main body 131 may be made of a metal material, or may be made of the same material as the second mold plate 103, and the protrusion main body 131 and the second mold plate 103 may be connected by integral molding, or may be connected by various welding methods. The bump pads 132 are made of an elastic material, and the bump pads 132 can be adhered to the side of the bump body 131 facing the wafer 100 by glue, as shown in fig. 10 a; alternatively, the raised cushion 132 may be resiliently nested on its own on the surface of the raised body 131, as shown in FIG. 10 b. The convex body 131 is a curved body or a polyhedron. The area of the surface of the bump cushion 132 contacting the wafer 100 is larger than the area of the notch 120.

In summary, the present invention provides a wafer plastic package method, a wafer level package structure, a packaging method thereof, and a plastic package mold, wherein a wafer loaded with a plastic package material is placed on a first template of the plastic package mold, and a second template of the plastic package mold applies pressure to the plastic package material to form a plastic package layer on a surface of the wafer deviating from the first template, wherein a protrusion is formed on a surface of the second template of the plastic package mold facing the wafer, and the protrusion is located above the notch when the second template applies pressure to the plastic package material and is used to prevent the plastic package material from overflowing from the notch, so as to achieve plastic package of a larger area, improve plastic package eccentricity, reduce a cutting area in a subsequent trimming process, and facilitate improvement of a utilization rate of an effective chip of the wafer.

The above description is only for the purpose of describing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention, and any variations and modifications made by those skilled in the art based on the above disclosure are within the scope of the appended claims.

Claims

1. A wafer plastic package method is characterized by comprising the following steps:

providing a wafer, wherein the edge of the wafer is provided with a notch;

adding a plastic packaging material on the wafer; and the number of the first and second groups,

placing the wafer on a first template of a plastic package mold, and applying pressure to the plastic package material through a second template of the plastic package mold so as to form a plastic package layer on the surface of the wafer deviating from the first template; the surface of the second template facing the wafer is provided with a protrusion, the protrusion is used for preventing the plastic package material from overflowing from the notch when the second template applies pressure to the plastic package material, the protrusion is made of an elastic material, and the original height of the protrusion is larger than the thickness of the plastic package layer.

2. The wafer plastic packaging method according to claim 1, wherein the protrusions abut against the notches of the wafer when the second template applies pressure to the plastic packaging material.

3. The wafer plastic package method according to claim 1, wherein the notch is V-shaped, and the protrusion is a cylinder or a triangular prism structure with a V-shaped concave.

4. The wafer plastic packaging method according to claim 1, wherein an area of a surface of the protrusion contacting the wafer is larger than an area of the notch.

5. The wafer plastic packaging method according to claim 1, wherein the plastic packaging layer is an epoxy resin layer.

6. A method according to claim 1, wherein the molding compound is heated after the molding compound is added on the surface of the wafer facing away from the first mold plate.

7. A method according to claim 6, wherein the heating temperature of the plastic packaging material is 160-180 ℃.

8. The wafer plastic packaging method according to claim 1, wherein a release film is attached to a surface of the second template facing the wafer.

9. A method according to claim 1, wherein the wafer is bonded to a carrier by a die attach film.

10. The wafer plastic package method according to claim 1, wherein after the plastic package layer is formed on the surface of the wafer away from the first template, demolding is performed, and the molded wafer is baked.

11. A wafer level chip packaging method, comprising the wafer plastic packaging method according to any one of claims 1 to 10.

12. The wafer-level chip packaging method of claim 11, wherein after the wafer is baked, further comprising,

carrying out an edge cutting process on the wafer, and removing the plastic packaging layer positioned at the edge of the wafer; and

and thinning or removing the carrier bearing the wafer.

13. The utility model provides a plastic package mould for carry out the plastic envelope to the wafer, its characterized in that, includes second template, first template and the unit of moulding plastics, first template is used for bearing the wafer, the unit of moulding plastics be used for to the wafer deviates from add plastic packaging material on the surface of first template, the second template is used for right plastic packaging material exerts pressure, the second template of plastic package mould towards be formed with a arch on the surface of wafer, the second template is right when plastic packaging material exerts pressure the arch is located the top of the breach at wafer edge is used for preventing plastic packaging material follows the breach overflows, wherein, the arch is made by elastic material, bellied original height is greater than follow-up plastic packaging material is in the thickness of the plastic packaging layer that forms on the wafer.

14. A plastic package mold according to claim 13, wherein the protrusion is adhered to the second mold plate of the plastic package mold by a glue.

15. The plastic package mold according to claim 13, wherein an area of a surface of the protrusion contacting the wafer is larger than an area of the notch.

16. The mold for plastic package according to claim 13, wherein the protrusion is a curved body or a polyhedron.

17. The plastic mold according to claim 13, wherein the protrusion comprises: the wafer support comprises a protrusion main body and a buffer pad, wherein the protrusion main body is connected with the second template, and the buffer pad is located on one surface, facing the wafer, of the protrusion main body.

18. The plastic package mold according to claim 17, wherein the protrusion main body is made of the same material as the second mold plate, and the protrusion main body is integrally molded and connected with the second mold plate, or the protrusion main body is connected with the second mold plate by welding.

19. The mold according to claim 17, wherein the bump pads are made of an elastic material, and the bump pads are adhered to the surface of the bump main body facing the wafer through glue, or the bump pads are nested on the surface of the bump main body.

20. A plastic package mold according to claim 18, wherein the convex main body is a curved body or a polyhedron.

21. A plastic package mold according to claim 18, wherein the area of the surface of the bump cushion contacting the wafer is larger than the area of the notch.