JP4821995B2 - Manufacturing method of semiconductor device - Google Patents

Description

The present invention relates to a manufacturing method of a preferred semiconductor equipment for making BGA (Ball Grid Array) type micro-thin corresponding CSP as a package (chip size package).

As one of the mounting forms capable of realizing an ultra-small and thin mounting package, there is a BGA type package structure that is mounted on a printed wiring board using solder balls as external connection terminals. In this BGA type package structure, since solder balls can basically be arranged on the entire surface of the flat surface of one mounting package, electrical connection with the printed wiring board becomes possible on the entire surface of the flat surface. As a result, the BGA package structure does not reduce the pitch between terminals (between leads) compared to a structure in which outer leads such as QFP (Quad Flat Package) are projected around the package. It has the excellent feature that it can cope with the increase in the number of pins, and can cope with ultra-small and thin mounting packages.
In such a BGA type mounting package, as an insulating substrate that is a base material that substantially (mechanically mechanically) supports the mechanical structure, it is thin while having appropriate mechanical strength and thermal strength. TAB tape that can be used is preferably used. As a mounting package using such a TAB tape, for example, a CSP such as a μBGA (trademark of Tessera, USA) package is known.

The μBGA package is a so-called tape BGA type CSP, in which a semiconductor chip is pasted on a TAB tape via an elastomer (low-elasticity resin), and an S-shape is formed between the semiconductor chip and the copper foil (wiring) of the TAB tape. It has a structure connected with inner leads bent into a mold. In this μBGA package, by interposing an elastomer between the semiconductor chip and the TAB tape, it is possible to relieve the thermal stress between them and prevent the occurrence of stress breakage at the solder ball joint. It is said.
In such a tape BGA type CSP, as one means for achieving ultra-small size and thickness, a bonding window is provided in the TAB tape, and the inner lead is bent into an S-shape at that portion, thereby forming a semiconductor. It has been proposed to connect to electrode pads on the chip.

That is, as shown in FIG. 3, the semiconductor chip 10 is affixed to the TAB tape 20 via the elastomer 30, but directly above the electrode pad 50 on the semiconductor chip 10 in the polyimide substrate 40 of the TAB tape 20. A bonding window (also referred to as a bonding window) 60 is provided at the position, and the inner lead 70 is formed in a state of being spanned over the bonding window 60. Here, the inner lead 70 is connected to a wiring pattern formed by patterning the copper foil 80 by a wet etching process or the like (that is, a part of the wiring pattern). In general, the wiring pattern is processed by patterning a liquid resist applied to the surface of the copper foil 80 by photolithography to form an etching resist, and wet etching using the resist.
Then, by using the bonding tool 100 to push down the inner lead 70 in the direction of the electrode pad 50, the inner lead 70 is cut at the notch portion 90, bent into an S shape, and placed on the electrode pad 50. Be struck.
The bonding window 60 is provided in the polyimide substrate 40 by a pressing method using a mold or the like before the copper foil 80 is laminated on the polyimide substrate 40 with an adhesive. Thereafter, the laminated copper foil 80 is subjected to pattern processing by a subtractive method (wet etching method or the like), and plating is performed in the final process, whereby the main part of the CSP structure of the tape BGA type is manufactured. (See Patent Document 1)

JP 2002-353361 A

  However, when the TAB tape manufactured as described above is actually used to manufacture a semiconductor device having a tape BGA type CSP structure, cracks and shapes are formed near the notch portion 90 of the inner lead 70. A defect or the like occurs, which becomes a serious defect, and it is difficult to reliably bond the inner lead 70. In addition, the conventional technique has not been able to grasp the main factors that cause such cracks and shape defects of the inner lead 70.

The present invention has been made in view of such problems, and its purpose is to crack and shape the inner lead in a TAB tape used in a CSP compatible with ultra-small and thin types such as a BGA type package. eliminate the occurrence of defects such as, by extension makes it possible to achieve a reliable connection of the inner lead to the electrode pad stably, it is to provide a manufacturing method of a semiconductor equipment.

The first method for fabricating a semiconductor device according to the present invention includes the steps of attaching a conductive foil on one surface of the insulating substrate bonding window is drilled, and the pattern processing the conductor foil by etching, notch A method of manufacturing a semiconductor device, comprising: a step of forming an inner lead having a shape that extends over the bonding window; and a step of cutting and bending the inner lead at the notch portion, The step of forming the inner lead is characterized in that a dry film is bonded to the surface of the conductive foil, the dry film is patterned, and the patterned dry film is used as an etching resist.

The manufacturing method of the second semiconductor equipment according to the present invention is the manufacturing method of the first semiconductor equipment, the dry film, using the following lamination roll 70 ° roll hardness 20 ° or more, the It is characterized by a laminate coating on the surface of the conductive foil.

Further, the third method for fabricating a semiconductor equipment according to the present invention is the manufacturing method of the first or second semiconductor equipment, and the dry film to the surface of the conductor foil, wherein the thermocompression bonding .

The fourth method of the semiconductor equipment manufacturing according to the present invention, the method of manufacturing the third semiconductor equipment, the temperature during the thermocompression bonding, lowest and the dry film and the conductive foil is adhered It is characterized in that the temperature is in the range of not less than the temperature and not more than the temperature obtained by adding 40 ° C. to the minimum temperature.

The fifth semiconductor equipment manufacturing method of the present invention, in the first to fourth one of a method of manufacturing a semiconductor equipment of the thickness of the dry film, and 3μm or 20μm or less It is characterized by that.

The manufacturing method of the sixth semiconductor equipment of the present invention, in any one of the manufacturing method of the semiconductor equipment of the first to fifth, the conductive foil after patterning, the insulating substrate TAB used for producing a BGA mounting structure including a step of attaching a semiconductor chip via an insulating elastic body and a step of forming a BGA mounting structure on the surface or the surface of the conductor foil It is characterized by manufacturing a tape.

According to the manufacturing method of the semiconductor equipment of the present invention, in the bonded surface of the conductive foil to the bonding window is drilled on an insulating substrate bonded a dry film etching resist to patterning the dry film And patterning the conductive foil using the etching method to form an inner lead having a notch and a shape spanning the bonding window, and cutting and bending the inner lead at the notch As a result, it is possible to stably realize the reliable connection of the inner lead to the electrode pad in the semiconductor chip or the like without causing cracks or shape defects in the inner lead.

Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view showing the main steps of a method for manufacturing a TAB tape for a semiconductor device according to the present embodiment.
In this method of manufacturing a wiring board, first, as shown in FIG. 1A, an TAB insulating substrate 1 made of a polyimide resin film having a surface coated with an adhesive is prepared. As shown in FIG. 1B, the insulating substrate 1 is provided with a feed hole 2 for TAB conveyance and a bonding window 3 formed by pressing using a precision mold.

  Subsequently, as shown in FIG. 1C, a copper foil 4 is laminated as a conductor foil for forming wiring on the surface of the insulating substrate 1. The thickness of the copper foil 4 may be set as appropriate in consideration of the specifications such as the wiring line / pitch required for the semiconductor device manufactured at this time and the pattern processing accuracy possible in the etching process.

Then, as shown in FIG. 1 (d), the dry film 5 is laminated on the surface of the copper foil 4 by a thermocompression bonding method using a laminating roll (not shown).
The thickness of the dry film 5 is 3 μm or more and 20 μm or less, based on the balance between the specifications of the wiring line / pitch and the like of a semiconductor device manufactured using this TAB tape and the pattern processing accuracy possible in the etching process. The thickness is appropriately set within the above thickness range.
In addition, the roll hardness of the laminate roll used in this laminate coating process is set to 20 ° to 70 °.
Moreover, the temperature of the thermocompression bonding in this laminate coating process is a temperature within a range not lower than the minimum temperature at which the dry film 5 and the copper foil 4 are in close contact with each other and 40 ° C. added to the minimum temperature. .

  Thereafter, as shown in FIG. 1E, exposure and development by a photolithography method are performed to pattern the dry film 5 to form a dry film resist pattern 5-2. A so-called backing is performed on the back side of the insulating substrate 1 using an etchant resistant resin 6 or the like.

  Subsequently, as shown in FIG. 1F, the copper foil 4 is patterned by the wet etching method using the dry film resist pattern 5-2 to form the wiring pattern 7, the inner lead 8, and the like. The inner lead 8 has a notch (not shown, the same applies hereinafter) and is formed in a shape that spans the bonding window 3. When the pattern processing by the wet etching method is completed, the dry film resist pattern 5-2 is peeled off.

  Then, as shown in FIG. 1G, Au plating 9 is applied to the surface of the wiring pattern 7 and the inner lead 8 in order to improve the bonding characteristics with the semiconductor chip (not shown) in the subsequent process. Apply.

  Thereafter, although not shown, a semiconductor chip is attached to a predetermined portion of the surface on which the wiring pattern 7 of the TAB tape is formed via an elastomer. Then, the inner lead 8 is pushed in the direction of the electrode pad on the semiconductor chip by using a bonding tool or the like, so that the inner lead 8 is cut at the notch portion and bent into an S-shape, and the electrode pad of the semiconductor chip. Hit it. Further, bonding is performed on other connection portions as well, so that the main part of the BGA mounting structure of the semiconductor device using the TAB tape is manufactured.

  According to the method for manufacturing a TAB tape for a semiconductor device according to the present embodiment, a liquid used as a resist used in an etching process for patterning the copper foil 4 to form the inner leads 8 and the wiring patterns 7 is used. Since the dry film 5 having superior flexibility and excellent in-plane film thickness uniformity is used instead of the resist, the insulating substrate 1, the copper foil 4, and the like are used when the copper foil 4 is patterned by the etching process. It is possible to eliminate the occurrence of cracks and shape defects in the notch portion of the inner lead 8 and the vicinity thereof due to the release of the strain stress between them.

The inventors of the present invention have conducted various experiments and studies in order to elucidate the factors that cause cracks and shape defects in the inner leads in the conventional manufacturing method in forming the present invention. It was confirmed that a liquid resist was used.
That is, the polyimide film tape base material on which the copper foil is laminated used as the base material of the TAB tape is generally formed after the bonding window 3 is formed in the insulating substrate 1 made of a polyimide film with an adhesive, and then the insulation is performed. Since the copper foil 4 is laminated (laminated) by applying tension to the surface of the conductive substrate 1, it is unavoidable between the polyimide film (insulating substrate 1) and the copper foil 4 during the lamination. , Strain stress potentially remains. For this reason, when the copper foil 4 is patterned by the etching process, the strain stress which has been latent up to that point is released at and near the etched portion. The released strain stress is concentrated in the notch portion of the inner lead 8 which is a weak material mechanics portion or the vicinity thereof, and is broken (cracked) into an etching resist (not shown) made of a liquid resist in that portion. And damage such as breakage (not shown). Then, the etching solution penetrates from the damaged portion of the etching resist, and the notch portion of the inner lead 8 that should originally be completely masked by the etching resist of the portion, or the vicinity thereof, or otherwise In addition, cracks and shape defects are generated in the wiring pattern 7 having a weak fine width as in the notch portion. As described above, in the conventional general manufacturing method, the liquid lead is damaged due to the released strain stress, so that the inner lead 8 or the like has cracks or shape defects. There was found.

  Therefore, in order to prevent the etching resist from being damaged even when the above-described strain stress is released in the etching process, in the manufacturing method of the TAB tape for a semiconductor device according to the present embodiment, the etching resist is 3 μm. A dry film 5 having a thickness of 20 μm or less is used.

  And the temperature below the temperature which added 40 degreeC to the minimum temperature more than the minimum temperature which can be thermocompression-bonded to the surface of the copper foil 4 using the laminate roll whose roll hardness is 20 degrees or more and 70 degrees or less for the dry film 5 By laminating under conditions, the dry film 5 can be laminated on the surface of the copper foil 4 so as not to be damaged even if the strain stress is released in a later etching process.

  Here, in this laminating process, there is a risk that reliable thermocompression bonding becomes difficult if a roll with a roll hardness of less than 20 ° is too soft, and if a roll with a roll hardness of over 70 ° is used, Since the bonding window 6 and the copper foil 4 in the vicinity thereof may be deformed at this time, the roll hardness of the laminate roll is preferably 20 ° or more and 70 ° or less.

  Further, if the dry film 5 is laminated under a condition where the fluidity is low, the amount of deformation of the dry film 5 can be reduced. It is desirable to set the temperature within a range equal to or lower than the temperature obtained by adding 40 ° C. to the minimum temperature.

  Further, if the dry film 5 is too thin, damage may occur due to the released strain stress as in the case of the liquid resist. Therefore, the thickness of the dry film 5 is desirably 3 μm or more. . Further, if the dry film 5 is too thick, there is no risk of damage, but patterning accuracy is hindered when the dry film 5 is patterned and used in the etching process as the dry film resist 5-2. Since there is a risk of a decrease, the upper limit of the thickness of the dry film 5 is desirably 20 μm.

  Here, measures such as avoiding damage to the etching resist due to strain stress by thick coating of the liquid resist can be considered, but in reality, the liquid resist is used with such thick coating. Therefore, various problems such as a decrease in productivity and variations in resist thickness due to a large increase in the exposure amount due to thick coating occur separately, which is not practical.

  As described above, according to the method for manufacturing a TAB tape for a semiconductor device according to the present embodiment, it is possible to eliminate the occurrence of cracks and shape defects in the inner leads 8 and, by extension, the electrode pads on the semiconductor chip. It is possible to stably realize a reliable connection of the inner lead to the like.

FIG. 2 is a comparison of notch width variation σ and the number of cracks between a TAB tape for a semiconductor device manufactured by the manufacturing method of one embodiment according to the present invention and a TAB tape for a semiconductor device manufactured by a conventional manufacturing method. FIG.
In this example, a TAB tape for a semiconductor device was manufactured using the dry film 5 having a thickness of 15 μm by the method described in the above embodiment. The reason why the thickness of the dry film 5 is set to 15 μm is that it has been found that if the thickness exceeds 20 μm, the pattern reproducibility by etching of the notch portion of the inner lead 8 is deteriorated. Further, the hardness of the roll made of rubber of the laminate roll used in the laminate coating by thermocompression bonding of the dry film 5 was set to 70 °. The roll hardness (substantially the hardness of the rubber of the rubber roll) was measured using a new JIS K6253 durometer type A spring type JIS hardness meter. Moreover, the temperature condition at the time of thermocompression bonding was set within the range of the lowest temperature minimum temperature + 40 ° C. at which the dry film 5 can be thermocompression bonded to the copper foil 4.

The numerical values of the evaluation results of each item shown in FIG. 2 are the evaluation target items (resist thickness, notch width (dimensional variation σ), cracks) in each TAB tape produced using a metal microscope (× 100 magnification). Number) was observed, measured, aggregated and evaluated. In addition, about the number of cracks, the number of units to be measured was set to 1000.
In the case of Comparative Example 1 manufactured by the manufacturing method using the conventional liquid resist, it was confirmed that the number of cracks was 280 due to the thin resist thickness made of liquid resist being 3 μm, and many cracks were generated. It was done.
Moreover, in the case of the comparative example 2, since the resist thickness which consists of a liquid resist was thickly coated with 6 micrometers, the number of cracks became 15, and the number of crack generations was able to be reduced significantly compared with the case of the comparative example 1. However, it could not be 0. Further, the required exposure amount was extremely high at 600 mJ, and the productivity was remarkably lowered. Further, the dimensional variation of the notch width was extremely large at 2.8σ, which is about twice that of Example 1.

  On the other hand, in the case of Example 1 according to the present invention, since the dry film 5 was used under the above-described condition setting, it was confirmed that the number of cracks was 0 and the occurrence of cracks could be completely eliminated. Moreover, since the required exposure amount is 100 mJ and only a very small exposure amount is required, it has been confirmed that productivity is significantly improved as compared with Comparative Example 1 and Comparative Example 2. In addition, the variation in notch could be reduced to σ = 1.6.

It is sectional drawing which shows the main processes of the manufacturing method of the TAB tape for semiconductor devices which concerns on embodiment of this invention. It is the figure which compared and showed about each item, such as notch width dispersion | variation (sigma) and the number of cracks, in Example 1 by this invention, and the comparative example 1 and the comparative example 2 by the conventional manufacturing method. It is sectional drawing which shows the inner lead bonding process in the conventional TAB tape for BGA type semiconductor devices.

Explanation of symbols

1 Insulating substrate 2 Feed hole 3 Bonding window 4 Copper foil 5 Dry film 5-2 Dry film resist pattern 7 Wiring pattern 8 Inner lead 9 Au plating

Claims (6)

A step of bonding a conductive foil on one surface of the insulating substrate bonding window is drilled,
Patterning the conductor foil by an etching method to form an inner lead having a notch portion and a shape spanning the bonding window;
Cutting the inner lead at the notch, and bending the semiconductor device.
The method of forming the inner lead includes a step of bonding a dry film on the surface of the conductor foil, patterning the dry film, and using the patterned dry film as an etching resist. In the manufacturing method of the semiconductor device according to claim 1,
A method of manufacturing a semiconductor device, comprising: laminating and coating the dry film on the surface of the conductive foil using a laminate roll having a rubber / plastic roll hardness of 20 ° to 70 ° according to JIS K6253. In the manufacturing method of the semiconductor device of Claim 1 or 2,
A method of manufacturing a semiconductor device, comprising: thermocompression bonding the dry film to a surface of the conductor foil. In the manufacturing method of the semiconductor device according to claim 3,
The temperature at the time of the thermocompression bonding is set to a temperature within a range that is equal to or higher than a minimum temperature at which the dry film and the conductive foil are in close contact with each other and is equal to or lower than a temperature obtained by adding 40 ° C. to the minimum temperature. Device manufacturing method. In the manufacturing method of the semiconductor device according to any one of claims 1 to 4,
A method of manufacturing a semiconductor device, wherein the dry film has a thickness of 3 μm to 20 μm. In the manufacturing method of the semiconductor device according to any one of claims 1 to 5,
After patterning the conductive foil, a step of attaching a semiconductor chip via an insulating elastic body on the surface of the insulating substrate or on the surface of the conductive foil;
A method of manufacturing a semiconductor device having a BGA mounting structure, comprising: forming a BGA mounting structure.