阅读说明：本技术 一种半导体芯片上表面感应区外露的封装方法 (Packaging method for exposing induction area on upper surface of semiconductor chip ) 是由 顾俊晔 付贵平 胡健 于 2020-07-15 设计创作，主要内容包括：本发明公开了一种半导体芯片上表面感应区外露的封装方法,尤其涉及一种芯片需要正面有小区外露于封装体的封装方式及结构。芯片表面预置光刻胶或其他高分子材料保护芯片表面的感应区功能区；通过引线键合工艺实现芯片与基材的电气连接；通过注塑工艺行程包封成；机械研磨包封层上表面,使其厚度达到要求,同时芯片表面预置的光刻胶或其他高分子材料外露于包封层；或者通过注塑模具在注塑成形时,使芯片上的高分子材料外露于包封层；通过化学药水或物理外力去除光刻胶或其他高分子材料,使芯片表面感应区外露与封装体。从而达到芯片正面感应区外露于封装体的封装方式及结构,同时优化了封装工艺,极大地降低了成本。(The invention discloses a packaging method for exposing an induction area on the upper surface of a semiconductor chip, and particularly relates to a packaging mode and a packaging structure for a chip requiring a front surface with a small area exposed out of a packaging body. The surface of the chip is preset with a photoresist or other high molecular materials to protect the induction area functional area on the surface of the chip; the electrical connection between the chip and the substrate is realized through a wire bonding process; packaging by an injection molding process; mechanically grinding the upper surface of the encapsulating layer to enable the thickness of the upper surface to meet the requirement, and simultaneously exposing the photoresist or other high polymer materials preset on the surface of the chip to the encapsulating layer; or the high polymer material on the chip is exposed out of the encapsulating layer when the high polymer material is subjected to injection molding through an injection mold; and removing the photoresist or other high polymer materials by chemical liquid medicine or physical external force to expose the chip surface induction area and the packaging body. Therefore, the packaging mode and the structure that the front sensing area of the chip is exposed out of the packaging body are achieved, the packaging process is optimized, and the cost is greatly reduced.)

1. A packaging method for exposing an induction area on the upper surface of a semiconductor chip is characterized by comprising the following steps:

step S1, after the high molecular material is pre-arranged on the front surface of the chip, the front surface of the chip is exposed and developed, so that only the high molecular material pre-arranged in the functional area on the front surface of the chip is reserved, and the bonding pad on the front surface of the chip is exposed, thereby realizing the protection of the functional area on the front surface of the chip, or only the high molecular material is directly pre-arranged in the functional area on the front surface of the chip, so that the bonding pad on the front surface of the chip is exposed, thereby realizing the protection of the functional;

Step S2, obtaining a pretreated chip through the step 1, and combining the back of the pretreated chip with a base material or a metal pad on the base material through a polymer bonding material;

step S3, connecting a metal lead with a pad on the front surface of the chip and a metal pin module prefabricated on the substrate by adopting a lead bonding process;

step S4, encapsulating the chip, the lead, the metal pin module and/or the metal pad, the polymer material of the front functional area of the chip and the polymer adhesive material of the back of the chip by an injection molding process to form an encapsulating layer; or encapsulating the polymer material of the functional area on the front side of the chip and the polymer bonding material on the back side of the chip to form an encapsulating layer, and keeping the encapsulating layer combined with the base material to form a uniform packaging body; or when an injection mold is used for injection molding, the upper surface of the mold cavity is directly contacted with the polymer material of the functional area on the front surface of the chip, so that the injection molding resin cannot be injected to the surface of the polymer material, and after the encapsulating layer is formed, the polymer material on the chip is directly exposed out of the encapsulating layer, at the moment, the step S5 is skipped, and the step S6 is directly carried out;

step S5, thinning the encapsulating layer in a mechanical grinding mode until the thickness of the encapsulating layer meets the requirement, and simultaneously exposing the high polymer material preset on the chip to the encapsulating layer;

And step S6, removing the polymer material in the front functional area by chemical liquid medicine to expose the front functional area of the chip to the encapsulating layer.

2. The method of claim 1, wherein the substrate is a printed circuit board, a substrate, a lead frame, or a stainless steel plate with circuitry.

3. The method as claimed in claim 1, wherein in step S1, the front surface of the chip is exposed and developed by spin-coating a layer of wet polymer material or attaching a layer of dry polymer material thereon, and then exposing and developing the front surface of the chip to retain only the wet polymer material or the dry polymer material on the functional region of the front surface of the chip, and removing the excess wet polymer material or the dry polymer material or the liquid polymer material on the other portions of the chip.

4. The method as claimed in claim 1, wherein in step S1, the liquid polymer material is printed on the functional region of the front surface of the chip by a screen printing process, only by pre-placing the polymer material directly on the functional region of the front surface of the chip.

5. The method as claimed in claim 1, wherein in step S3, when the chip and the metal pin module are connected by the metal leads, the height of the metal leads does not exceed the height of the polymer material in the front functional region of the chip.

6. The method of claim 5, wherein in step S5, the encapsulating layer is thinned by mechanical grinding until the polymer material pre-disposed in the functional region of the front surface of the chip is exposed out of the encapsulating layer and ground to a height above the loop height of the metal leads.

7. The method as claimed in claim 1, wherein the metal pin module and/or the metal pad is made of any one of gold, nickel, silver, copper, palladium and tin, or is formed by stacking more than one of gold, nickel, silver, copper, palladium and tin.

8. The method as claimed in claim 1, wherein in step S6, the height of the front functional region of the chip is lower than the upper surface of the encapsulating layer to form a trench structure; the encapsulation material is filled to the edge of the front side of the chip, so that the chip is protected to the maximum extent, and high operability and high reliability are realized.

9. The method as claimed in claim 1, wherein in step S6, the chemical solution is a neutral Ph chemical solution, so as to remove the polymer material pre-disposed in the functional region on the front surface of the chip without damaging the functional region on the front surface of the chip and/or the metal pad.

Technical Field

The invention relates to a packaging mode that a chip front side induction area is exposed out of a packaging body, belonging to the technical field of semiconductors.

Background

Semiconductor chips are used in various industries with increasingly wide and complex applications, especially for sensor chips. For example: in the application of a fingerprint chip or an optical sensor chip, the sensing area of the chip is exposed on the surface of the package body for transmitting optical signals.

In the prior packaging process, a special-shaped mold is required for plastic packaging, so that the surface of the chip is exposed out of the surface of the packaging body. However, when the special-shaped mold is used for injection molding, a great pressure is required to act on the surface of the chip, and the risk of damaging the chip is high. Meanwhile, the application flexibility of the special-shaped die is poor, and different designs of chips require development of different special-shaped dies, so that the packaging cost is very high.

Disclosure of Invention

The purpose of the invention is: the dependence on the special-shaped die is reduced, the risk of damaging the chip in the packaging process is reduced, and meanwhile, the packaging cost of the exposed chip is greatly reduced.

In order to achieve the above object, the present invention provides a method for packaging a semiconductor chip with an exposed sensing region on an upper surface thereof, comprising the steps of:

step S1, after the high molecular material is pre-arranged on the front surface of the chip, the front surface of the chip is exposed and developed, so that only the high molecular material pre-arranged in the functional area on the front surface of the chip is reserved, and the bonding pad on the front surface of the chip is exposed, thereby realizing the protection of the functional area on the front surface of the chip, or only the high molecular material is directly pre-arranged in the functional area on the front surface of the chip, so that the bonding pad on the front surface of the chip is exposed, thereby realizing the protection of the functional;

Step S2, obtaining a pretreated chip through the step 1, and combining the back of the pretreated chip with a base material or a metal pad on the base material through a polymer bonding material;

step S3, connecting a metal lead with a pad on the front surface of the chip and a metal pin module prefabricated on the substrate by adopting a lead bonding process;

step S4, encapsulating the chip, the lead, the metal pin module and/or the metal pad, the polymer material of the front functional area of the chip and the polymer adhesive material of the back of the chip by an injection molding process to form an encapsulating layer; or encapsulating the polymer material of the functional area on the front side of the chip and the polymer bonding material on the back side of the chip to form an encapsulating layer, and keeping the encapsulating layer combined with the base material to form a uniform packaging body; or when an injection mold is used for injection molding, the upper surface of the mold cavity is directly contacted with the polymer material of the functional area on the front surface of the chip, so that the injection molding resin cannot be injected to the surface of the polymer material, and after the encapsulating layer is formed, the polymer material on the chip is directly exposed out of the encapsulating layer, at the moment, the step S5 is skipped, and the step S6 is directly carried out;

step S5, thinning the encapsulating layer in a mechanical grinding mode until the thickness of the encapsulating layer meets the requirement, and simultaneously exposing the high polymer material preset on the chip to the encapsulating layer;

And step S6, removing the polymer material in the front functional area by chemical liquid medicine to expose the front functional area of the chip to the encapsulating layer.

Preferably, the substrate is a printed wiring board, a substrate, a lead frame, or a stainless steel plate with a circuit.

Preferably, in step S1, when performing exposure and development on the front surface of the chip, a layer of wet polymer material or a dry polymer material is first coated on the front surface of the chip by spin coating, and then exposure and development are performed to leave only the wet polymer material or the dry polymer material on the functional region on the front surface of the chip and remove the excess wet polymer material or the dry polymer material on the other portion of the chip.

Preferably, in step S1, the liquid polymer material is printed on the functional region of the front surface of the chip by a screen printing process, with the polymer material being pre-disposed only on the functional region of the front surface of the chip.

Preferably, in step S3, when the chip and the metal pin module are connected by the metal leads, the height of the wire loop of the metal leads does not exceed the height of the polymer material in the functional region on the front surface of the chip.

Preferably, in step S5, the encapsulating layer is thinned by mechanical grinding until the polymer material pre-disposed in the functional region on the front side of the chip is exposed out of the encapsulating layer, and the polymer material is ground to a height higher than the wire loop height of the metal lead.

Preferably, the metal pin module and/or the metal pad is made of any one of gold, nickel, silver, copper, palladium and tin, or is composed of a metal lamination of more than one of gold, nickel, silver, copper, palladium and tin.

Preferably, in step S6, the height of the functional region on the front surface of the chip is lower than the upper surface of the encapsulating layer, so as to form a trench structure; the encapsulation material is filled to the edge of the front side of the chip, so that the chip is protected to the maximum extent, and high operability and high reliability are realized.

Preferably, in step S6, the chemical solution is a chemical solution with a neutral Ph value, so that the functional region on the front surface of the chip and/or the metal pad are not damaged while the polymer material preset in the functional region on the front surface of the chip is removed.

The invention presets a photoresist or other high molecular materials on the surface of the chip to protect the effective area of the front surface of the chip, thereby avoiding damaging the chip in the packaging process. The packaging method provided by the invention can be realized by adopting a mature process without using a special-shaped die, so that the packaging cost of exposed chips is greatly reduced.

Drawings

FIG. 1 is a side view of the chip and a schematic structural diagram of the chip;

FIG. 2 is a side view and a schematic structural diagram of a chip with a photoresist or other polymer material on the top surface.

FIG. 3 is a side view and a schematic structural view of a chip after pretreatment;

FIG. 4 is a side view and a schematic diagram of a chip pre-processed and then placed on a substrate by an adhesive material;

FIG. 5 is a side view and schematic diagram of a metal pin module with a chip surface pad connected to a substrate by a metal wire;

FIG. 6 is a side view and a schematic structural diagram of an encapsulation layer formed by encapsulating a chip, a pin or a circuit, a pad, a photoresist or a polymer material preset on the chip surface, an adhesive material on the chip back surface, and a lead by using an injection molding process;

FIG. 7 is a schematic side view and a schematic structural view of the encapsulating layer with a desired thickness and exposed photoresist or other polymer material on the upper surface of the chip;

FIG. 8 is a side view and a schematic diagram of a structure after removing the photoresist or other polymer material on the upper surface of the chip;

FIG. 9 is a side view and a schematic structural view of a chip, a pre-disposed photoresist or polymer material on the surface of the chip, an adhesive material on the back of the chip, and a lead wrapped with resin to form an encapsulating layer after injection molding, the encapsulating layer being combined with a printed circuit board or a ceramic substrate;

FIG. 10 is a schematic side view and a schematic structural view of the chip after the encapsulation layer is thinned by mechanical polishing to meet the required thickness, the photoresist or other polymer material on the upper surface of the chip is exposed out of the encapsulation layer, and the photoresist or other polymer material on the upper surface of the chip is removed;

FIG. 11 is a schematic process flow diagram of an embodiment of the present invention.

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

As shown in fig. 11, the method for packaging a semiconductor chip with an exposed sensing region on the upper surface thereof according to the present invention comprises the following steps:

step S1: as shown in fig. 2, a photoresist or other polymer material 3 is pre-disposed on the front surface active area of the chip 1 having the metal pad 2 on the front surface as shown in fig. 1, so as to protect the front surface active area of the chip 1. For example, a layer of wet photoresist or other polymer material may be spin-coated or a layer of dry photoresist or other polymer material 3 may be attached to the surface of the chip 1.

As shown in fig. 3, exposure and development are then performed to leave the photoresist or other polymer material 3 only on the active area of the front surface of the chip 1, and the excess photoresist or other polymer material is removed.

Or directly printing liquid photoresist or other high molecular materials 3 on the active area of the front surface of the chip 1 by a screen printing process.

Step S1 is to expose the metal pad 2 on the front surface of the chip 1 for subsequent wire bonding process. While protecting the active area of the front side of the chip 1.

Step S2: as shown in fig. 4, the back surface of the chip 1 is bonded to the metal pad 5 on the base material by an adhesive material 8. The bonding material 8 can be a polymer material, silver paste, or glue.

Step S3: as shown in fig. 5, the metal pads 2 on the front surface of the chip 1 and the upper surface of the metal pin module 4 of the frame base material are connected by the metal wires 6 by wire bonding, so as to realize electrical connection.

Step S4: as shown in fig. 6, the chip 1, the metal leads 6, the metal pin module 4, the metal pads 2, 5, and the photoresist or other polymer material 3 in the active area of the front surface of the chip 1 and the polymer adhesive material 8 on the back surface of the chip 1 are encapsulated by injection molding to form an encapsulating layer 7.

Or as shown in fig. 9, the chip 1, the metal leads 6, the photoresist or other polymer material 3 in the active area of the front surface of the chip 1, and the polymer adhesive material 8 on the back surface of the chip 1 are encapsulated to form an encapsulating layer 7, and the encapsulating layer 7 is combined with the substrate to form a unified package.

Step S5: as shown in fig. 7, the upper surface of the encapsulating layer 7 is thinned by mechanical grinding, and the photoresist or other polymer material 3 pre-disposed on the front surface of the chip 1 is exposed out of the encapsulating layer 7. Or when an injection mold is used for injection molding, the upper surface of the cavity of the mold is directly contacted with the polymer material 3 of the functional area on the front surface of the chip 1, so that the injection resin cannot be injected to the surface of the polymer material, and the polymer material on the chip is exposed out of the encapsulating layer;

step S6: as shown in fig. 8, the photoresist or other polymer material 3 pre-disposed on the front surface of the chip 1 is removed by chemical liquid or physical external force. The chemical liquid medicine has no limitation on pH value, and neutrality is optimal. The surface of the chip is not damaged.