KR100821962B1 - Fabrication method of wafer-level flip chip package using acf/ncf solution - Google Patents

Abstract

A method for fabricating a wafer-level flip-chip package using an ACF/NCA solution is provided to effective suppress shadow effect by directly coating a material of a solution stage having a composition of an ACA(anisotropic conductive adhesive) film or NCA(non-conductive adhesive) film on a wafer. After a mixture solution including insulation polymer resin, a hardening agent and an organic solvent is deposited on a wafer(100) with a non-solder bump(113), the deposited mixture solution(115) is dried to transform the mixture deposited on the wafer into a B-stage. The dried wafer is diced into individual chips. After the diced semiconductor chips(200) are aligned with an electrode of a substrate(300), heat and pressure is applied to perform a flip-chip bonding process. The mixture solution can include a conductive particle having 5~20 weight percent with respect to the insulation polymer resin.

Description

Fabrication Method of Wafer-Level Flip Chip Package Using ACF / NCF Solution

1 is an example of the manufacturing method of the present invention, Figure 1 (a) shows a wafer, Figure 1 (b) shows a cutting surface (AB) of Figure 1 (a), Figure 1 ( c) shows the cut surface AB of the wafer to which the mixture solution is applied, and FIG. 1 (d) shows the flip chip connection of the diced individual chips.

* Explanation of symbols for the main parts of the drawings *

100: wafer, 110: chip on wafer

111: semiconductor material 112: input / output pad

113: non-solder bump 114: passivation layer

115: coated mixed solution 200: individual chips diced

300: substrate 310: electrical wiring on the substrate

The present invention can produce a flip chip package by directly coating anisotropic conductive adhesives (ACA) or non-conductive adhesives (NCA) in solution state on a wafer. It is about how.

Electronic package technology is a very broad and diverse system manufacturing technology including all stages from semiconductor devices to final products, and is particularly important in achieving miniaturization, light weight, and high performance of devices at the rapid pace of development of electronic products. Electronic package technology is a very important technology that determines the performance, size, price and reliability of the final electronic product. Particularly in today's electronics that pursue high performance, ultra small / high density, low power, multifunction, ultra-fast signal processing, and permanent reliability, ultra-small packaged parts are essential parts for computers, telecommunications, mobile communications, and high-end consumer electronics. Among them, flip chip technology, which is one of the technologies for mounting a chip on a substrate, is currently used in display packaging such as smart cards, LCDs, and PDPs, computers, mobile phones, and communication systems. The range of application is expanding.

There are two main types of flip chip technologies: solder flip chips using solder and non-solder flip chips without solder. Solder flip chips have complex connection processes such as solder flux application, chip / substrate alignment, solder bump reflow, flux removal, underfill filling and hardening, which leads to increased production cost. Therefore, non-solder flip chip technology has recently emerged to reduce such complicated processes.

The representative technology of non-solder flip chip is flip chip technology using ACA. Conventional flip chip technology using ACA has a process of coating or temporarily attaching ACA material on a substrate, aligning the chip with the substrate, and finally applying heat and pressure to complete the flip chip package. However, this process has a long process time that requires the formation of a film or the application or provisional adhesion of ACA material to each substrate.

Therefore, in recent years, there has been a great deal of interest in the wafer dimension package technology for coating and processing a polymer material having a function of flux and underfill in a wafer state. In recent years, compared to conventional solder flip chips, flip chip connections using conductive adhesives have the advantages of low-cost, ultra-fine electrode pitch, and lead-free, environmentally friendly fluxless and low temperature processes. Technology development is in progress.

Adhesives used in electronic packaging are divided into films and pastes according to their use forms, and are classified into conductive, anisotropic conductive, and non-conductive according to whether they contain conductive particles or not. Therefore, adhesives used in electronic packaging include anisotropic conductive film (ACF), anisotropic conductive paste (ACP), and non-conductive film (NCF). And non-conductive pastes (NCPs).

Film adhesives (ACF, NCF) and paste adhesives (ACP, NCP) differ greatly in form and composition. First, the ACF includes an organic solvent that helps coatability in the composition to enable coating in the form of a film, and is coated and then commercialized after drying the organic solvent.

Unlike the film, the ACP is applied directly onto the substrate by a method such as dispensing to perform a flip chip process, so that an organic solvent is not included in order to prevent bubbles from forming inside. It is also marketed as a paste in a syringe.

US Pat. No. 5,323,051 (Semiconductor wafer level package) is a technique of bonding another cap wafer with a glass adhesive in a wafer state and cutting the wafer into individual chips, which is very different from applying the ACA of the present invention and using it for package connection. Is another patent.

Another US Pat. No. 5,918,113 (Process for producing a semiconductor device using anisotropic conductive adhesive) is a method for electrically connecting the ACA to the substrate and then electrically connecting the semiconductor chip to the substrate by heat and pressure, but the present invention provides the ACA in a wafer state. It is a very different technique in terms of pre-application to non-solder bump formed chips.

The literature, published by SHShi et al. (Development of the Wafer Level Compressive-Flow Underfill Process and Its Required Materials, 1999, ECTC, pp.961-966), describes the use of underfill materials with solder flux on wafers with solder bumps. After coating, each chip is diced and aligned on a substrate using a conventional SMT assembly apparatus. This demonstrates how to simplify the process of placing underfill material between the chip and the substrate after conventional solder reflow connections.

Korean Patent No. 10-0361640 (Wafer type flip chip package manufacturing method using coated anisotropic conductive adhesive) has a process method of transferring onto a wafer through a lamination process method applying heat and pressure after coating on a release paper film in the case of ACF, In the case of ACP, the process method of coating on a wafer by spray, doctor blade, or meniscus is specified. Therefore, when using the film form, a lamination process for placing the film on the wafer and applying heat and pressure, and a process for removing the release paper are required, and when the film form ACA or NCA is attached to the uneven wafer surface, the shadow effect is shown. It is easy to control the thickness of the coating when using the paste form disadvantages.

An object of the present invention is to effectively suppress the shadow effect that is likely to occur on uneven wafer surface by using a simple process having high productivity, easy to control the thickness of the coating, and lose the potential of curing through simple drying. Wafer-type flip-chip package with ACA or NCA to obtain anisotropic conductive adhesives (ACAs) or non-conductive adhesives (NCAs) at levels of semi-cured initial state It is to provide a manufacturing method.

In the method of manufacturing a wafer-type flip chip package of the present invention, (a) a mixture solution containing an insulating polymer resin, a curing agent, and an organic solvent is applied onto a wafer on which a non-solder bump is formed, and then dried to radius the mixture applied on the wafer. Initializing the B-stage, dicing the dried wafer into individual chips, aligning the semiconductor chips diced with the individual chips with electrodes of a substrate, and then applying heat and pressure to flip chip connections. It has a feature that is produced, including the step of.

The core idea of the present invention is to form an anisotropic conductive film (ACF) or a non-conductive film (NCF; NCF) in a solution state using an organic solvent, not in the form of a film. The present invention provides a wafer-type flip chip package by directly applying a non-solder bump on a wafer.

According to the core idea of the present invention, the manufacturing method of the present invention does not require a lamination process and a process of removing the release paper because the coating method is a solution using an organic solvent rather than a film form, and a method of controlling rheological properties such as viscosity Through this, it is possible to effectively suppress the shadow effect that is likely to occur on the uneven wafer surface, and it is easy to control the thickness of the coating by using a solution containing a composition similar to the composition of ACF or NCF, and volatilize the organic solvent. By simple drying, the initial state of semi-curing can be obtained.

The compositional characteristics of the ACF and the NCF are the same except for the presence or absence of the conductive particles, so that the ACF solution may be prepared by further adding 5 to 20 parts by weight of the conductive particles based on the weight of the insulating polymer resin. The conductive particles may be conductive particles conventionally used in ACF or ACP, but are preferably metal particles coated with gold, silver, nickel, metal coated polymer, conductive polymer or insulating polymer, or mixtures thereof. Preferred and more preferably gold particles, silver particles, nickel particles, gold coated polymers, silver coated polymers, nickel coated polymers, gold particles coated with insulating polymers, silver particles coated with insulating polymers or insulating More preferably, the polymer is coated nickel particles, or mixtures thereof, most preferably nickel particles, gold coated polymers, nickel coated polymers or nickel particles coated with insulating polymers, or mixtures thereof. Most preferred.

With reference to Figure 1 will be described in more detail the manufacturing method of the present invention. However, the illustrated FIG. 1 is only shown for ease of description and the present invention is not limited by FIG. 1.

As shown in FIGS. 1A and 1B, the wafer 100 to which the mixture solution is applied is a wafer manufactured through a general semiconductor process, and typically, many chips 110 exist on one wafer. Each chip is provided with an input / output terminal (I / O pad) 112 for connecting an electrical signal to the outside.

At this time, the type of the chip is not particularly limited, and may be, for example, a display driving circuit IC, an image sensor IC, a memory IC, a non-memory IC, an ultrahigh frequency or RF IC, or a semiconductor IC or a compound semiconductor IC mainly composed of silicon. have.

A non-solder bump 113 is formed on the input / output terminal, and the non-solder bump is formed of a metal stud bump or metal plating bump, a gold stud bump, a copper stud bump, a gold plating bump formed by using a bonding wire bonder or a plating method. , Copper plated bumps, electroless nickel / gold bumps or electroless nickel / copper / gold bumps, wherein the top of the wafer where the non-solder bumps are not formed is typically passivated with an insulating material 114. to be.

As shown in Fig. 1 (c), the ACF or NCF mixture solution is applied onto the nonsolder bump formed side of the wafer by spraying, doctor blade, meniscus, spin coating, screen printing, stencil printing or comma roll coating. do. The mixture-coated wafer is dried at 70 to 80 ° C. for 1 to 4 minutes to volatilize the organic solvent, and through the drying, the applied mixture 115 passes through an uncured state (A-satge) where it is likely to flow. It maintains its shape at room temperature and can be manipulated to have a semi-cured initial state (B-stage) that has fluidity when heated. The initial state of semi-curing means that the initial state of curing does not lose the potential for curing to occur only above a certain high temperature, even in the semi-cured state from the start of curing to the end of curing, and the dried mixture is 180 to 200 It has a curing property that can be cured within 10 to 30 seconds at ℃.

At this time, the thickness of the applied mixture is preferably 10 to 100㎛ after the drying. This is because physical adhesion necessary for flip chip connection can be obtained in the above range, and the shadow effect is minimized, and electrical insulation and electrical connection are smoothly performed on the chip.

The wafer coated with the mixture is mounted on a wafer dicing machine and diced into individual chips 200, symbol 200 shown in FIG. 1 (d), based on the scribe line of the wafer. Since the diced individual chips 200 are the same as those in which the semi-cured ACF or NCF is bonded, they can be used as one flip chip package. Aligning the individual chips with the electrodes 310 of the substrate 300 and applying heat and pressure using a flip chip bonder to cure the mixture to form a flip chip assembly in which the individual chips and the substrate are physically and electrically connected. You can get it.

As described above, the core idea of the present invention is to prepare ACF or NCF in the form of a solution rather than a film and to directly coat the wafer. Thus, the mixture solution mixes the organic solvent and materials constituting the commonly used ACF or NCF. Preferably, the mixture solution may be a mixture of 100 to 400 parts by weight of a curing agent and 50 to 200 parts by weight of an organic solvent, based on the weight of 100 of the insulating polymer resin, more preferably of the insulating polymer resin. More preferably, 120 to 375 parts by weight of the curing agent and 80 to 150 parts by weight of the organic solvent are mixed based on the weight of 100.

The insulating polymer resin is a thermoplastic resin or a thermosetting resin, the thermoplastic resin is an acrylic resin, a phenoxy resin or a rubber, or a mixture thereof, and the thermosetting resin is an epoxy resin or a polyimide resin, or a mixture thereof. The organic solvent is preferably selected from toluene, methyl ethyl ketone, acetone, dimethylformamide or cyclohexane, or a mixture thereof, and the curing agent is preferably selected from imidazole or amine, or a mixture thereof. .

The weight ratio of the organic solvent is a weight ratio optimized for attaching an adhesive in the form of a film by coating and drying the mixture solution containing a composition similar to the material constituting the ACF or NCF on the surface of a wafer to be manufactured. The weight ratio of the organic solvent that determines the rheological properties is preferably controlled by the nonuniformity of the wafer surface, such as the thickness of the non-solder bumps or the number of non-solder bumps.

According to the present invention, a material having a composition of an anisotropic conductive adhesive film or a non-conductive adhesive film is directly coated on a wafer in a solution state so that a process of laminating an anisotropic conductive adhesive film or a non-conductive adhesive film on a wafer and removing a release paper is necessary. It has high productivity and the process is simple, and the coating is done in solution rather than film, which effectively suppresses the shadow effect that is likely to occur on uneven wafer surface, and is difficult to apply in anisotropic conductive adhesive paste or non-conductive adhesive paste. There is an advantage that it is easy to control the thickness of, and through the simple drying to volatilize the organic solvent has the advantage of obtaining a level of the initial semi-cured state does not lose the potential of curing.

Claims (10)

(a) applying a mixture solution comprising an insulating polymer resin, a curing agent, and an organic solvent onto a wafer on which a non-solder bump is formed, and then drying to make the initially applied mixture on the wafer a semi-stage; (b) dicing the dried wafer into individual chips; And (c) aligning the semiconductor chip diced with the individual chip with an electrode of a substrate, and then flip-chip connecting by applying heat and pressure; Method of manufacturing a flip chip package comprising a. The method of claim 1, The mixture solution of step (a) further comprises 5 to 20 parts by weight of conductive particles based on the weight of the insulating polymer resin. The method of claim 1, The method of manufacturing a flip chip package, characterized in that the coating of step (a) is carried out by spraying, doctor blade, meniscus, spin coating, screen printing, stencil printing or comma roll coating. The method of claim 1, Drying of step (a) is characterized by drying at 70 to 80 ° C. for 1 to 4 minutes to volatilize the organic solvent and bring the applied mixture to an initial B-stage at a level that does not lose the potential for curing. Method for producing a flip chip package. The method of claim 4, wherein The dried mixture is a manufacturing method of a flip chip package, characterized in that having a curing time of 10 to 30 seconds at 180 to 200 ℃. The method of claim 1, The method of manufacturing a flip chip package, characterized in that the thickness of the mixture solution applied in step (a) is 10 to 100㎛ after the drying. The method of claim 1, The mixture solution of step (a) is a method for manufacturing a flip chip package, characterized in that 100 to 400 parts by weight of a curing agent and 50 to 200 parts by weight of an organic solvent are mixed based on the weight 100 of the insulating polymer resin. The method of claim 7, wherein The insulating polymer resin is a thermoplastic resin or a thermosetting resin, the thermoplastic resin is an acrylic resin, a phenoxy resin or a rubber, or a mixture thereof, and the thermosetting resin is an epoxy resin or a polyimide resin, or a mixture thereof. Method for producing a flip chip package. The method of claim 7, wherein The organic solvent is a toluene, methyl ethyl ketone, acetone, dimethylformamide or cyclohexane, or a mixture thereof. The method of claim 2, The conductive particles are gold, silver, nickel, metal-coated polymer, conductive polymer or insulating polymer-coated metal particles, or a mixture thereof.

Images