JP2002110855A - Semiconductor device and its manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a manufacturing method of a semiconductor device that lumps a semiconductor wafer together on a wafer before the semiconductor wafers are divided into chips, forms a circuit for rewiring, carries out wire bonding, performs dicing, and divides each chip into pieces to reduce the costs of a wafer level package. SOLUTION: On a light-sensitive insulating resin layer formed on the entire surface of the semiconductor wafer, a bonding pad for mounting a soldering ball, a bonding finger for connecting to the chip, and a circuit (circuit for rewiring) for connecting the bonding pad to bonding finger are formed repeatedly corresponding to each chip on the wafer. After that, an opening for the wire bonding is provided in the insulating resin layer. Through the opening, the pad on the chip and the bonding finger are collectively subjected to wire bonding and dicing for dividing each chip into pieces.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing a wafer-level package which contributes to miniaturization and cost reduction of a semiconductor device.

[0002]

2. Description of the Related Art In recent years, with the demand for higher functionality and lighter, thinner and smaller electronic devices, high-density integration and high-density mounting of electronic components have been progressing. Semiconductor packages used in these electronic devices have become smaller and have more pins, and mounting substrates for mounting electronic components including the semiconductor packages have also become smaller. Furthermore, in order to enhance the storage in electronic devices, a rigid flex board, which is formed by laminating and integrating a rigid board and a flexible board, and which can be bent, has been used as a mounting board.

[0003] With the miniaturization of semiconductor packages,
In a conventional package using a lead frame, the miniaturization has reached its limit. Recently, a BGA (Ball) has been used as a package mounted on a circuit board.
Grid Array), CSP (Chip Sc)
ALE Package) has been proposed. In these semiconductor packages, the electrical connection between the electrodes of the semiconductor chip and the terminals of the substrate made of various materials such as plastics and ceramics, which are called semiconductor package substrates and have the function of the lead frame of the conventional semiconductor package. As a typical connection method, a wire bonding method or TAB (Tape Automated Bon
ding) method, and furthermore, FC (Flip Chip)
Although there are known methods such as BGA and C using an FC connection method which is advantageous for miniaturization of a semiconductor package,
The structure of the SP has been actively proposed. However, these packages have to be individually packaged and tested after singulating the semiconductor chips, which has been a factor that increases the cost.

[0004] For this reason, various companies have proposed a method of packaging and testing all at once before singulating a semiconductor chip. Among them, a method of forming an insulating layer having a stress relaxation function on a wafer with a resin and bonding between the pad and a pad provided on the insulating layer using wire bonding, which is a conventional bonding technique, is the highest dimension. It has attracted attention as a method that can balance reliability and cost.

[0005]

A pad for mounting a solder ball on a resin film with an adhesive, a bond finger for connection to a chip, and a connection between the two, as conventionally proposed. Is repeatedly formed corresponding to each chip on the wafer, an opening for wire bonding for connection between the chip and the circuit is formed, and the method for attaching the opening to the wafer has the above structure. Although it is possible to fabricate a semiconductor device having the above, there is a problem of the positional accuracy of the bonding to increase the diameter of a wafer useful for cost reduction, and it is predicted that the yield will decrease.

[0006] In addition, router processing is expensive,
In the case of press working, when the arrangement of the wire bonding pads is changed due to the chip design, it is necessary to renew the punching die for forming the opening every time, which is expected to be a factor that increases the cost.

As a result of various studies, the inventors have found that a pad for mounting a solder ball directly on the surface of a semiconductor wafer, a bond finger for connection to a chip, and a circuit for connecting the two are formed on the wafer. It is formed repeatedly for each chip, and the opening for wire bonding is similarly made using a negative or positive photosensitive system according to each chip on the wafer, using a predetermined developer such as an alkali or a solvent. By forming on the wafer, a predetermined opening and a circuit for rewiring can be formed at a predetermined position with a good yield, and even when the diameter of the wafer is increased, the opening due to a change in the chip design can be achieved. A method of manufacturing a semiconductor device (Japanese Patent Application No. 2000-187937) has been proposed which can easily cope with a change in shape. When it is necessary to increase the thickness of the resin layer for the instrumentation improved reliability, reduced film of the insulating resin layer has a problem such as prone.

Therefore, the present invention has been studied further,
Forming two insulating resin layers directly on the semiconductor wafer surface,
A circuit for rewiring is formed thereon repeatedly corresponding to each chip on the wafer, and a wire bonding opening is also formed on the first layer in contact with the wafer in accordance with each chip on the wafer. Is formed by screen printing, the second layer is formed on a wafer by a predetermined developing solution such as an alkali or a solvent using a negative-type or positive-type photosensitive system, with a good yield, a predetermined opening at a predetermined position and A circuit for rewiring can be formed, and it is possible to cope with an increase in the diameter of the wafer, and it can easily cope with a change in the shape of the opening due to a change in the chip design.
The present invention aims to provide a method for manufacturing a semiconductor device that can easily increase the thickness of an insulating layer.

[0009]

That is, the present invention provides a bonding pad for mounting solder balls and a connection for connection with a chip on an insulating resin layer formed on the entire surface of a semiconductor wafer which is an aggregate of semiconductor chips. Finger for connection and circuit to connect both (circuit for rewiring)
Are repeatedly formed corresponding to each chip on the wafer, and then an opening for wire bonding is provided in the insulating resin layer, and the pad and the bond finger on the chip are collectively wired through this opening. After bonding, dicing is performed to singulate each chip. Further, an insulating resin layer is formed by screen printing, and a resin layer (first layer) on the side in contact with the wafer is formed. A resin layer (second layer) on a side not in contact with the wafer, which is formed on one layer and is made of a photosensitive resin, and is formed of two resin layers. Forming a rewiring circuit, exposing and developing a photosensitive resin by photolithography, and providing an opening for wire bonding penetrating the two layers. It is a manufacturing method.

According to the manufacturing method of the present invention, first, a first insulating resin layer is formed on a surface of a semiconductor wafer by screen printing. At this time, a screen is formed on an opening for wire bonding so as not to print the resin. It is formed. Furthermore, a photosensitive insulating resin layer is formed thereon,
The opening of the first layer is buried or covered. Thereafter, a circuit for rewiring (bonding pads for mounting solder balls, bond fingers for connection to a chip, and a circuit for connecting the two) is formed, and then a second layer made of a photosensitive resin is formed. The main purpose is to expose and develop the insulating resin layer by photolithography, provide an opening for wire bonding, wire-bond all at once through this opening, and dice to separate each chip. And

[0011] As a method of forming a circuit for rewiring, specifically, a copper foil with a photosensitive insulating resin is attached to a first insulating resin layer formed by screen printing, with the copper foil surface facing outside. Or, paste a dry film made of photosensitive insulating resin, or apply liquid photosensitive insulating resin,
Dry to form an insulating resin layer, paste copper foil on it,
Or after forming a copper foil layer by electroless plating,
Using the copper foil, a circuit is formed by a subtractive method or a semi-additive method. Alternatively, a circuit may be formed by an additive method on an insulating resin layer formed using a dry film or a liquid photosensitive insulating resin.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The first insulating resin layer can be applied to any resin capable of being screen-printed, and is cured by light or heat after being screen-printed. The second insulating resin layer is a photosensitive insulating resin layer, and a resin for forming the second resin layer mainly includes a component that reacts with a light beam having a specific wavelength such as ultraviolet light and a component that reacts with heat. It has a composition suitable for a negative or positive type exposure and development system. Further, the total thickness of the formed first and second insulating resin layers is desirably 30 to 200 μm, preferably 45 to 150 μm, in consideration of the reliability and the package volume after the semiconductor device is formed.

The photosensitive insulating resin for forming the second insulating resin layer is supplied in the form of a copper foil (RCC) with a photosensitive insulating resin, a dry film, or a liquid resin. It is possible to select the supply mode. In the case of RCC and dry film, a photosensitive insulating resin is attached to the wafer surface using a means such as a roll laminator or a press. On the other hand, in the case of a liquid resin, the resin is applied to the surface of the wafer using a means such as a spin coater, a screen printing machine, and a curtain coater and dried to form an insulating resin layer. At this time, the opening of the first layer is covered again with the resin, and after the second layer is formed, the wafer is not exposed. When a dry film and a liquid resin are used, a copper foil is further attached on the insulating resin layer as necessary.

On the insulating resin layer thus formed, a rewiring circuit is formed at a position corresponding to the design of the semiconductor wafer, but by a generally known circuit forming method. Any of the subtractive method, the semi-additive method, and the additive method can be applied. When the RCC is used, the subtractive method or the semi-additive method can be selected depending on the thickness of the copper foil by using the copper foil constituting the same as it is. The semi-additive method can be selected by forming the power supply layer by a method such as an additive method or sputtering on the surface from which the copper foil is removed by etching. When a dry film or a liquid resin is used, the surface of the photosensitive insulating resin is directly subjected to a full additive method, sputtering, or 2 to 8 μm.
The semi-additive method can be applied if the power supply layer is formed by attaching an ultrathin copper foil having a thickness of m. further,
If a copper foil having a normal thickness is attached, a subtractive method can be selected.

By forming the alignment marks required for forming these circuits on the wafer in advance, it becomes possible to form the circuits at predetermined positions with high accuracy.

The photosensitive insulating resin layer having the rewiring circuit on the surface prepared as described above is formed on the opening of the underlying first layer by a photolithography technique.
Exposure is performed to expose the wire bonding pad portion of the wafer. In the case of the positive type, a photomask prepared in advance is used so that the opening is exposed, and in the case of the negative type, the opening is shielded from light.

Next, the exposed photosensitive insulating resin is developed with a predetermined developing solution to expose a wire bonding pad portion thereunder. As a developing solution for this purpose, generally known sodium carbonate, sodium hydroxide, tetramethylammonium hydride (T
MAH), an organic solvent and the like are selected according to the composition of the photosensitive resin used, and are adjusted to an appropriate concentration before use. Subsequently, the photosensitive insulating resin serving as the second insulating resin layer is reacted and cured by heating to form a solder resist layer, which is subjected to a post-process such as wire bonding and solder ball mounting.

For wire bonding, it is necessary to apply a surface treatment to a portion to be stitched at the time of wire bonding of the rewiring circuit so that bonding can be easily performed. Alternatively, a method of gold plating after coating nickel with electroless plating, or a method of gold plating after coating nickel with electrolytic plating or electroless plating on the entire circuit formation site or a necessary portion before forming a circuit. Can be adopted. When the electrolytic plating method is used after forming the circuit, it is necessary to form a power supply lead in advance, and to remove the lead portion by an etching method or the like after the plating step. Further, when a method of processing the entire portion of the circuit to be formed before the circuit is formed, the circuit can be formed by a subtractive method using this as an etching mask. In addition, high connection reliability can be obtained by performing the same processing on a portion where a solder ball is mounted.

[0019]

EXAMPLES The present invention will be described below in detail with reference to examples, but the present invention is not limited thereto.

Example 1 A photocurable resin mainly composed of phenol novolak and epoxy resin is printed on the surface of a semiconductor wafer by screen printing so that a wire bonding pad of each chip is exposed, and ultraviolet rays are applied for 2 J. Irradiation resulted in photo-curing to form a 70 μm-thick first insulating resin layer. An MEK solution of a novolak-based positive photosensitive resin was applied thereon by a spin coater to a thickness of 30 μm and dried at 70 ° C. for 20 minutes, and then an electrolytic copper foil having a thickness of 18 μm was further coated on the roll laminator. To obtain a structure.

Next, a liquid plating resist is applied on the structure by a spin coater and dried, and a wire bond finger, a solder ball pad, and a portion to be a circuit for connecting them are formed by photolithography. After the opening, a nickel layer having a thickness of 5 μm and a gold layer having a thickness of 1 μm were formed by electrolytic plating. Thereafter, the plating resist was peeled off with a 3% aqueous solution of sodium hydroxide, and then the copper foil was etched with an alkaline etchant using the gold plating layer as a resist, thereby forming a conductor circuit immediately below the gold plating layer.

Further, the resin surface of the structure from which the copper foil has been removed by etching is developed using a stepper so that a portion on a wire bond pad formed on a wafer below the resin layer can be developed and opened. 2.38% exposed
The resin at a predetermined position is dissolved and removed with an aqueous solution of TMAH, and the surface is irradiated with ultraviolet rays at 500 mJ, and then heated at 150 ° C. for 1 hour, thereby covering the surface of the wafer with a resin opening for wire bonding and gold plating. Fully cured total thickness of 92μ with wire bond fingers, solder ball pads and circuits connecting them
m structures were obtained.

In the structure obtained in this manner, a solder resist is provided on the insulating resin and the circuit provided thereon, and the chip and the circuit on the insulating resin are joined by a gold wire through the resin opening. After that, the resin opening and the periphery of the wire bond finger were sealed with a printing sealing resin. Furthermore, it was confirmed that the solder ball was mounted at a predetermined position and did not hinder the operation as a semiconductor device.

(Example 2) A thermosetting resin mainly composed of an epoxy resin is printed on the surface of a semiconductor wafer so that a wire bonding pad of each chip is exposed.
It is cured by heating at 150 ° C. for 2 hours and has a thickness of 9
A first insulating resin layer of 0 μm was obtained. Further, a novolak-type negative photosensitive resin ME was formed on an electrolytic copper foil having a thickness of 18 μm.
The K solution was applied by casting with a bar coater,
By drying for 10 minutes at 80 ° C. for 0 minutes, a thickness of 1
An RCC made of a 10 μm novolak type negative photosensitive resin and a copper foil was obtained. This RCC was attached to the first insulating resin layer by a roll laminator to obtain a structure. Next, on this structure, dry film etching resist is stuck by a roll laminator to form an etching resist layer, and except for the parts that should be a circuit for connecting wire bond fingers, solder ball pads, and them, After opening by photolithography, unnecessary copper foil was removed by an etching solution containing a ferric chloride aqueous solution as a main component to form a conductor circuit.

Further, the surface of the resin from which the copper foil has been removed by etching is developed on a portion on the wire bond pad.
Exposure using a parallel light exposure machine so that the aperture can be opened; 2.
The resin at a predetermined position is dissolved and removed with a 38% TMAH aqueous solution, and the surface is irradiated with ultraviolet rays at 500 mJ.
By heating at 1 ° C for 1 hour, a fully cured thick layer thickness with a resin opening for wire bonding, a wire bond finger whose surface is coated with gold plating, a solder ball pad, and a circuit connecting these, on the wafer An insulating resin layer composed of two insulating resin layers of 190 μm was obtained.

The thus obtained chip with an insulating layer is provided with a solder resist on an insulating resin and a circuit provided thereon, and a 5 μm-thick electrolytic plating on a conductor circuit present in the opening of the solder resist. And a 0.5 μm thick gold layer was formed thereon. afterwards,
After the chip and the circuit on the insulating resin were joined by the gold wire via the resin opening, the resin opening and the periphery of the wire bond finger were sealed with the printing sealing resin. Furthermore,
Solder balls were mounted at predetermined positions, and it was confirmed that operation of the semiconductor device was not hindered.

Example 3 A photocurable resin mainly composed of phenol novolak and epoxy resin was printed on the surface of a semiconductor wafer by screen printing so that the wire bonding pads of each chip were exposed. Irradiation resulted in photo-curing to obtain a first insulating resin layer having a thickness of 105 μm. Furthermore, PET of 25 μm thickness
MEK of novolak type negative photosensitive resin on film
The solution was cast and applied with a bar coater, and 10
For 10 minutes at 80 ° C.
A dry film composed of a novolak type negative photosensitive resin having a thickness of μm and a PET film was obtained. This dry film was attached to the first insulating resin layer by a roll laminator to obtain a structure.

Next, a power supply layer is provided on the entire surface of the structure by sputtering, and a liquid plating resist is applied thereon by a spin coater to form a wire bond finger, a solder ball pad, and the like for connecting them. After opening a part to be a circuit by photolithography, there is 5 μm
A copper layer having a thickness of 6 μm, a nickel layer having a thickness of 6 μm thereon, and a gold layer having a thickness of 1 μm were further formed thereon. After that, the plating resist was removed, and the nickel-gold layer was used as a resist, and flash etching was performed using perhydrogen sulfuric acid to form a conductor circuit.

Further, the surface of the resin from which the copper foil has been removed by etching is developed on a portion on the wire bond pad.
Exposure using a parallel light exposure machine so that the aperture can be opened; 2.
The resin at a predetermined position is dissolved and removed with a 38% TMAH aqueous solution, and the surface is irradiated with ultraviolet rays at 500 mJ.
By heating at 1 ° C for 1 hour, a fully cured thick layer thickness with a resin opening for wire bonding, a wire bond finger whose surface is coated with gold plating, a solder ball pad, and a circuit connecting these, on the wafer A 123 μm insulating resin layer was obtained.

In the thus obtained chip with an insulating layer, a solder resist is provided on the insulating resin and the circuit provided thereon, and the chip and the circuit on the insulating resin are connected by a gold wire through the resin opening. After joining, the resin opening and the periphery of the wire bond finger were sealed with a printing sealing resin. Furthermore, it was confirmed that the solder ball was mounted at a predetermined position and did not hinder the operation as a semiconductor device.

Example 4 A photocurable resin mainly composed of phenol novolak and epoxy resin is printed on the surface of a semiconductor wafer by screen printing so that a wire bonding pad of each chip is exposed, and ultraviolet rays are irradiated for 2 J. Irradiation was performed to cure the photo-resist, thereby obtaining a first insulating resin layer having a thickness of 97 μm. Further, by screen printing, a printing ink containing a phenol novolak negative photosensitive resin as a main component is printed on the entire surface of the wafer including the opening of the first layer by using a screen printing machine, and the printing is performed at 60 ° C. for 10 minutes. By drying at ℃ for 10 minutes, the thickness of 70μ
m of the second resin layer was obtained.

Next, a power supply layer is provided on the entire surface of the structure by electroless plating, and a liquid plating resist is applied thereon by a spin coater, and wire bond fingers, solder ball pads, and the like are connected. After forming a part to be a circuit for photolithography, a 5 μm thick copper layer was formed thereon by electrolytic plating, a 6 μm thick nickel layer was formed thereon, and a 1 μm thick gold layer was formed thereon. . After that, the plating resist was removed, and the nickel-gold layer was used as a resist, and flash etching was performed using perhydrogen sulfuric acid to form a conductor circuit.

Further, the surface of the resin from which the copper foil has been removed by etching is developed on a portion on the wire bond pad.
Exposure using a parallel light exposure machine so that the aperture can be opened; 2.
The resin at a predetermined position is dissolved and removed with a 38% TMAH aqueous solution, and the surface is irradiated with ultraviolet rays at 500 mJ.
By heating at 1 ° C for 1 hour, a fully cured thick layer thickness with a resin opening for wire bonding, a wire bond finger whose surface is coated with gold plating, a solder ball pad, and a circuit connecting these, on the wafer A 155 μm insulating resin layer was obtained.

In the chip with the insulating layer obtained in this way, a solder resist is provided on the insulating resin and the circuit provided thereon, and the chip and the circuit on the insulating resin are connected by a gold wire through the resin opening. After joining, the resin opening and the periphery of the wire bond finger were sealed with a printing sealing resin. Furthermore, it was confirmed that the solder ball was mounted at a predetermined position and did not hinder the operation as a semiconductor device.

Example 5 A photocurable resin mainly composed of phenol novolak and epoxy resin was printed on the surface of a semiconductor wafer by screen printing so that the wire bonding pads of each chip were exposed, and ultraviolet rays were applied for 2 J. Irradiation resulted in photo-curing to obtain a first insulating resin layer having a thickness of 105 μm. Furthermore, PET of 25 μm thickness
MEK of novolak type negative photosensitive resin on film
The solution was cast and applied with a bar coater, and 10
For 10 minutes at 80 ° C.
A dry film composed of a novolak type negative photosensitive resin having a thickness of μm and a PET film was obtained. This dry film was attached to the first insulating resin layer by a roll laminator to obtain a structure.

Next, a power supply layer is provided on the entire surface of the structure by sputtering, and a liquid plating resist is applied thereon by a spin coater to form a wire bond finger, a solder ball pad, and a connection for connecting them. After opening a part to be a circuit by photolithography, there is 5 μm
A copper layer having a thickness of 6 μm, a nickel layer having a thickness of 6 μm thereon, and a gold layer having a thickness of 1 μm were further formed thereon. After that, the plating resist was removed, and the nickel-gold layer was used as a resist, and flash etching was performed using perhydrogen sulfuric acid to form a conductor circuit.

Further, the surface of the resin from which the copper foil has been removed by etching is developed on a portion on the wire bond pad.
Exposure using a parallel light exposure machine so that the aperture can be opened; 2.
The resin at a predetermined position is dissolved and removed with a 38% TMAH aqueous solution, and the surface is irradiated with ultraviolet rays at 500 mJ.
By heating at 1 ° C for 1 hour, a fully cured thick layer thickness with a resin opening for wire bonding, a wire bond finger whose surface is coated with gold plating, a solder ball pad, and a circuit connecting these, on the wafer A 123 μm insulating resin layer was obtained.

The chip with the insulating layer obtained in this manner is provided with a solder resist on the insulating resin and the circuit provided thereon, and the chip and the circuit on the insulating resin are connected by a gold wire through the resin opening. After joining, the resin opening and the periphery of the wire bond finger were sealed with a printing sealing resin. Furthermore, it was confirmed that the solder ball was mounted at a predetermined position and did not hinder the operation as a semiconductor device.

[0039]

According to the present invention, an insulating resin layer having an opening for wire bonding can be easily formed on a semiconductor wafer, which is an aggregate of semiconductor chips, at a wafer level. The cost of the package can be reduced.

Claims (7)

[Claims] 1. A bonding pad for mounting a solder ball, a bonding finger for connecting to a chip, and a connection between the both, on an insulating resin layer formed on the entire surface of a semiconductor wafer which is an aggregate of semiconductor chips. Circuit (rewiring circuit) is repeatedly formed corresponding to each chip on the wafer, an opening for wire bonding is provided in the insulating resin layer, and the pad on the chip is passed through the opening. A method for manufacturing a semiconductor device, comprising: performing wire bonding on a chip and a bond finger at a time, and then dicing the semiconductor chip into individual chips. 2. The semiconductor device according to claim 1, wherein the insulating resin layer comprises two resin layers, and the resin layer (first layer) on the side in contact with the wafer is formed by screen printing. Production method. 3. When forming the first layer by screen printing, a portion to be an opening for wire bonding is formed by:
3. The method of manufacturing a semiconductor device according to claim 2, wherein printing is performed by opening the wafer so that the wafer is exposed. 4. The semiconductor device according to claim 2, wherein the resin layer (second layer) on the side of the insulating resin layer made of two resin layers that is not in contact with the wafer is made of a photosensitive resin. Manufacturing method. 5. A second layer is formed on the first layer by screen printing so as to cover the opening (wafer exposed part), and after forming a rewiring circuit on the second layer, 4. The method according to claim 3, wherein an opening is provided in the second layer by a photolithographic method at the same position as the opening of the first layer, and an opening penetrating the first and second layers is formed. A method for manufacturing a semiconductor device according to claim 4. 6. A second layer is formed on the first layer by applying a liquid resin using a spin coater so as to cover the opening (wafer exposed portion), and the second layer is formed on the second layer. After the rewiring circuit is formed, an opening is provided in the second layer at the same position as the opening in the first layer by a photolithographic method, and an opening penetrating the first and second layers is formed. The method for manufacturing a semiconductor device according to claim 3, wherein: 7. A second layer supplied in a form coated on a copper foil or a resin film is pasted on the first layer so as to cover the opening (exposed portion of the wafer). After the rewiring circuit is formed on the two layers, an opening is provided in the second layer at the same position as the opening of the first layer by a photolithographic method, and the opening penetrating the first and second layers is provided. The method of manufacturing a semiconductor device according to claim 3, wherein: