JP4666887B2 - Adhesive sheet and method for manufacturing semiconductor chip with adhesive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an adhesive sheet and a method for manufacturing a semiconductor chip with an adhesive.
[0002]
[Prior art]
Conventionally, a silver paste has been mainly used for joining a semiconductor element and a semiconductor element mounting support member. However, with the recent miniaturization and high performance of semiconductor elements, the support members used are required to be small and fine. In response to these requirements, silver paste meets the above requirements due to occurrence of defects during wire bonding due to protrusion or inclination of semiconductor elements, difficulty in controlling the thickness of the adhesive layer, and generation of voids in the adhesive layer. It has become impossible to deal with. Therefore, in recent years, sheet-like adhesives have been used in order to cope with the above requirements.
[0003]
This adhesive sheet is used in the individual piece bonding method or the wafer back surface bonding method. When manufacturing a semiconductor device by using the former individual piece adhesion method adhesive sheet, the reel-like adhesive sheet is cut or cut into individual pieces by punching, and then the individual pieces are adhered to a supporting member and attached with the adhesive sheet. A semiconductor device is obtained by joining a semiconductor element separated by a dicing process to a support member to produce a support member with a semiconductor element, and then performing a wire bonding process, a sealing process, and the like as necessary. Become.
However, in order to use the adhesive sheet of the piece pasting method, a dedicated assembly device that cuts out the adhesive sheet and adheres it to the support member is necessary, so that the manufacturing cost is higher than the method using silver paste. There was a problem of becoming.
[0004]
On the other hand, when a semiconductor device is manufactured using the latter wafer back surface bonding type adhesive sheet, first, the adhesive sheet is pasted on the back surface of the semiconductor wafer, and further a dicing tape is pasted on the other surface of the adhesive sheet. Thereafter, the semiconductor element is separated from the wafer by dicing, and the separated semiconductor element with an adhesive sheet is picked up and joined to a support member. A semiconductor device is obtained through subsequent processes such as heating, curing, and wire bonding.
This wafer back surface bonding type adhesive sheet does not require an apparatus for separating the adhesive sheet to bond the semiconductor element with the adhesive sheet to the support member, and the conventional silver paste assembling apparatus is used as it is or a heating plate is used. It can be used by modifying a part of the device such as adding. Therefore, it has been attracting attention as a method in which the manufacturing cost can be kept relatively low among the assembling methods using the adhesive sheet.
[0005]
However, in the method using the adhesive sheet of the wafer back surface pasting method, two pasting steps for pasting the adhesive sheet and the dicing tape are necessary until the dicing step, and therefore it is necessary to simplify the work process. There has been proposed a method in which an adhesive sheet is attached on a dicing tape and this is attached to a wafer. (For example, refer patent documents 1-3.).
[0006]
[Patent Document 1]
JP 2002-226996 A [Patent Document 2]
JP 2002-158276 A [Patent Document 3]
JP-A-2-32181 [Patent Document 4]
JP 2002-192367 A [Patent Document 5]
Japanese Patent Laid-Open No. 2003-1457
[Problems to be solved by the invention]
The method of attaching the adhesive sheet on the dicing tape and affixing it to the wafer is preferable in that the application process to the wafer is one time and the adhesive can be cut at the same time when dicing the wafer, but the adhesive is cut at the same time. In order to achieve this, it is necessary to slow down the cutting speed, leading to an increase in cost.
On the other hand, as a method of cutting the chip, it is easy to form a modified layer selectively inside the wafer by half dicing, which is a method of processing a groove to be creased without completely cutting the chip, and laser irradiation. A technique (see Patent Document 4 and Patent Document 5) such as a laser processing method (stealth dicing) that can be cut has an effect of reducing defects such as chipping particularly when the wafer is thin. In these cutting methods, since the adhesive cannot be cut at the same time, the above steps cannot be taken. From the above points, the method of attaching the adhesive sheet on the dicing tape and attaching it to the wafer is a single application process to the wafer, and the adhesive can be cut at the same time, but the dicing efficiency is low, and the semi-cut There was a problem that this method cannot be used.
[0008]
[Means for Solving the Problems]
In order to solve the above problems, the present invention has the following configuration.
The adhesive sheet of the present invention has an adhesive force between the wafer and the adhesive layer provided on the base film, which is greater than the adhesive force between the base film and the adhesive force is manifested by heating. To produce a chip with an adhesive by having an adhesive layer provided with an adhesive and cutting the wafer that has been bonded and cut or semi-cut onto the upper surface of the adhesive layer into chips without using a cutting blade The adhesive layer has a configuration in which a groove is formed in the vicinity of a lower portion of a portion where the wafer is cut or half-cut .
The groove is formed by printing the adhesive layer in a shape having a groove on the base film, or by removing the sheet-like adhesive into the groove shape by etching or punching with a mold. The element shape is formed up to the middle of the film thickness of the base film or halfway of the adhesive layer. Moreover, it has an alignment means for aligning with a wafer on the said adhesive bond layer or a base film. The alignment means has a configuration that is a mark formed by etching or punching with a mold, or printing, an adhesive with a laser beam, or a modification of a base film.
[0009]
In the method for manufacturing a semiconductor chip with an adhesive using the adhesive sheet, the wafer is cut or semi-cut into a semiconductor element shape after aligning a predetermined position of the wafer with the alignment mark of the adhesive sheet. At this time, the adhesive sheet near the lower portion of the wafer to be cut or semi-cut does not have an adhesive layer or has a groove.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
In the method for manufacturing a semiconductor chip with an adhesive using the adhesive sheet of the present invention, it is not necessary to cut the adhesive during dicing, so that the dicing speed can be increased. Moreover, when half dicing, stealth dicing, etc. are performed and the wafer is later divided to obtain chips, the adhesive sheet is cut for each chip, so that a semiconductor chip with an adhesive can be easily obtained.
[0011]
As a base film used for this invention, plastic films, such as a polytetrafluoroethylene film, a polyethylene terephthalate film, a polyethylene film, a polypropylene film, a polymethylpentene film, a polyimide film, etc. are mentioned, for example. Further, surface treatment such as primer coating, UV treatment, corona discharge treatment, polishing treatment and etching treatment may be performed as necessary.
The base film preferably has adhesiveness, and an adhesive layer may be provided on one side of the base film. This can be formed by applying and drying a resin composition having an appropriate tack strength obtained by adjusting the ratio of the liquid component and the Tg of the high molecular weight component in the resin composition.
In the case where the adhesive layer has appropriate tackiness, the substrate film may not have tackiness. As such an adhesive layer, you may provide an adhesive layer in the single side | surface of a base film. In this case, since the process of providing the adhesive layer on the base film can be omitted, the adhesive sheet can be manufactured at a low cost. The tacky adhesive layer can increase the tack strength by increasing the ratio of liquid resin such as liquid epoxy resin and decreasing Tg of the high molecular weight component.
[0012]
The adhesive sheet of the present invention preferably has heat resistance and moisture resistance required when a semiconductor element is mounted on a semiconductor element mounting support member.
Further, when used in manufacturing a semiconductor device, it has an adhesive force that prevents the semiconductor element from scattering during dicing, and after that, it must be peeled off from the substrate film during pickup. For example, if the adhesive is too sticky, the resin at the groove ends may be fused, making separation difficult. For this reason, it is preferable to appropriately adjust the tack strength of the adhesive sheet. As a method for this, by increasing the fluidity of the adhesive at room temperature, the adhesive strength and the tack strength tend to increase, and the fluidity is lowered. If this is done, the fact that the adhesive strength and tack strength tend to decrease may be utilized. For example, in order to increase fluidity, there are methods such as increasing the plasticizer content and increasing the tackifier content. Conversely, when the fluidity is lowered, the content of the compound may be reduced. Examples of the plasticizer include monofunctional acrylic monomers, monofunctional epoxy resins, liquid epoxy resins, acrylic resins, and epoxy-based so-called diluents.
[0013]
There is no particular limitation as long as it satisfies the above characteristics, but because it has an appropriate tack strength and good handleability in the form of a sheet, in addition to the thermosetting component and the high molecular weight component, a curing accelerator, Catalysts, additives, fillers, coupling agents, high molecular weight components, etc. may be included. High molecular weight components include polyimide, (meth) acrylic resin, urethane resin, polyphenylene ether resin, polyetherimide resin, phenoxy resin, and modified polyphenylene. Although ether resin etc. are mentioned, it is not limited to these.
[0014]
Examples of the thermosetting component include an epoxy resin, a cyanate resin, a phenol resin, and a curing agent thereof, and an epoxy resin is preferable in terms of high heat resistance. The epoxy resin is not particularly limited as long as it is cured and has an adhesive action. Bifunctional epoxy resins such as bisphenol A type epoxy, novolac type epoxy resins such as phenol novolac type epoxy resin and cresol novolac type epoxy resin, and the like can be used. Moreover, what is generally known, such as a polyfunctional epoxy resin, a glycidyl amine type epoxy resin, a heterocyclic ring-containing epoxy resin, or an alicyclic epoxy resin, can be applied.
[0015]
Although there is no restriction | limiting in particular in the thickness of an adhesive bond layer, 5-250 micrometers is preferable for both an adhesive bond layer and a base material. If the thickness is less than 5 μm, the stress relaxation effect tends to be poor.
[0016]
In addition, as a method of laminating the adhesive sheet on the base film, in addition to printing, a pre-made adhesive sheet can be pressed on the base film, and a hot roll laminating method can be mentioned. A hot roll laminating method is preferable in terms of good points.
In the adhesive sheet in which an adhesive is provided on an adhesive base film, a method for forming a groove in the adhesive layer includes a method of printing the adhesive on the base film, printing or laminating a sheet-like adhesive. Then, the method of removing an unnecessary part by methods, such as the punching method which cut | disconnects an adhesive bond layer with an etching and a metal mold | die, and cut | disconnects to the middle of a base film, is mentioned.
The width of the groove is preferably about 0 to 5 mm, and the depth is preferably about the same as or greater than the thickness of the adhesive layer.
Moreover, the same effect is acquired also when the groove | channel of thickness 1/10 or more and 1 or less of an adhesive bond layer is formed. In this case, in order to completely cut the adhesive layer, it is preferable to include a step of expanding the adhesive sheet after cutting or semi-cutting the wafer. In addition, when the depth of a groove | channel is 1/10 or more and 1 or less in thickness of an adhesive bond layer, a groove | channel is easy to form compared with the case where a groove | channel penetrates an adhesive bond layer, and the edge part of an adhesive bond layer peels. There is an advantage that problems such as these are hardly generated.
[0017]
Examples of the method for cutting the wafer include cutting with a diamond saw and cutting with a laser beam. Examples of the method of half-cutting the wafer include cutting with a diamond saw and cutting with stealth dicing.
[0018]
The groove may be only in the vicinity of the cut portion of the wafer, but the groove may be formed over the entire surface of the adhesive so as to form a mesh of 0.01 mm to 1 mm. In this case, since a groove is always present in the vicinity of the cut portion of the wafer, alignment is not required or high-precision alignment is not required, which is preferable in that the manufacturing cost can be reduced. In this case, although the groove remains in the adhesive at the bottom of the chip, the groove disappears due to the flow of the adhesive at the time of pasting, so that reliability is not lowered. In addition, when a large number of grooves are formed, it is preferable that the grooves are formed in a lump in a mold because the grooves can be formed at low cost.
[0019]
When the groove is formed only in the vicinity of the cut portion of the wafer, it is necessary to align the wafer with the adhesive sheet provided with an adhesive on the adhesive base film. There is a method of using two intersections of a part of a linear portion of the outer periphery of a wafer and a circle and aligning the intersection with an alignment mark provided on an adhesive or a base film.
In this case, it is preferable to have a mark for alignment of the wafer on the adhesive layer or the base film, and after aligning the alignment mark and several points on the outer periphery of the wafer, The positional deviation between the cut portion and the groove can be reduced.
[0020]
(Example)
Hereinafter, it demonstrates in detail using the Example of this invention. The present invention is not limited to these. Although description will be made with reference to FIGS. 1 to 8, components having the same functions in the drawings are denoted by the same reference numerals and description thereof is omitted.
FIG. 1 is a cross-sectional explanatory view of an adhesive sheet 10 including an adhesive film 1 and an adhesive layer 2.
Furukawa Electric Co., Ltd. product was used for the adhesive film 1 provided with adhesive 1 '. As the adhesive layer 2, HS-232 (trade name, manufactured by Hitachi Chemical Co., Ltd.) was used. These were laminated with a hot roll laminator (Riston manufactured by Du Pont). This is held at 40 ° C. for a certain time to form the adhesive sheet 10.
[0021]
The adhesive sheet 10 is pressed with a mold to form a groove 11 corresponding to the shape of the semiconductor element (see FIG. 2).
Since the groove 11 is formed (stopped) up to the middle of the adhesive (base material) film 1, the adhesive sheet 10 can be handled as a film. The adhesive layer 2 of the adhesive sheet 10 is placed on a predetermined work table so that the wafer surface is in close contact.
[0022]
Next, as shown in FIG. 3, the semiconductor wafer A to be diced is attached to the upper surface of the adhesive layer 2. The laminating temperature at this time is usually between 20 ° C and 200 ° C. The laminating temperature is preferably 20 ° C. to 130 ° C. in terms of less warping of the wafer, and more preferably 20 ° C. to 80 ° C. in terms of low elongation of the base film.
Subsequently, half dicing, cleaning, and drying steps are added to the semiconductor wafer A in this attached state. Thereafter, by bending the wafer A, it can be completely cut into chips. At this time, since the semiconductor wafer A is sufficiently adhered and held on the adhesive sheet 10 by the adhesive layer 2, the chip does not fall off during each of the above steps. 4 and 5 show that semiconductor elements A1, A2 and A3 can be obtained by dicing 6 the wafer A using a dicing cutter.
[0023]
As shown in FIG. 6, the semiconductor elements A1, A2, and A3 to be picked up are picked up by the suction collet 4, for example. At this time, instead of the suction collet 4 or in combination with the suction collet 4, the semiconductor elements A1, A2, A3 to be picked up can be pushed up from the lower surface of the base film 1 by, for example, a needle rod.
Since the adhesive force between the semiconductor element A1 and the adhesive layer 2 is larger than the adhesive force between the adhesive layer 2 and the base film 1, when the semiconductor element A1 is picked up, the adhesive layer 2 is It peels in the state which adhered to the lower surface of semiconductor element A1 (refer FIG. 6).
[0024]
Next, the semiconductor elements A1, A2, and A3 are placed on the semiconductor element mounting support member 5 through the adhesive layer 2 and heated. The adhesive layer 2 exhibits an adhesive force by heating, and the bonding between the semiconductor elements A1, A2, and A3 and the semiconductor element mounting support member 5 is completed (see FIG. 7).
Here, formation of alignment means (marks) for alignment between the adhesive sheet 10 and the wafer A will be described with reference to FIG.
The first mark 20 and the circle of the wafer A corresponding to the first mark 20 are located at a position corresponding to the intersection of the round shape A20 on the outer shape of the wafer A placed on the adhesive sheet 10 and the orientation flat (straight line portion) A10. A second mark 22 is formed at the position of the adhesive sheet 10 corresponding to the intersection with the shape A20. The first and second marks 20 and 22 are holes formed in the adhesive sheet 10 by etching or punching with a mold. Or it is the mark formed by modification | denaturation of the adhesive bond layer 2 and the base film 1 by printing and a laser beam.
Moreover, the adhesive sheet 100 shown in FIG. 9 shows an example in which the groove 110 is formed partway through the adhesive layer 2. This adhesive sheet 100 also has the same effect as the adhesive sheet 10 described above. Furthermore, the groove 110 can be easily formed. In order to completely cut the adhesive layer 2 of the adhesive sheet 100, the wafer is placed, then diced, expanded, and the chip is picked up.
[0025]
Using the same method as described above, a semiconductor device sample (a solder ball is formed on one side) in which a semiconductor element and an adhesive sheet and a wiring board using a polyimide film with a thickness of 25 μm as a base material is produced, and heat resistance and moisture resistance are produced. I investigated.
As the evaluation method for heat resistance, reflow crack resistance and temperature cycle resistance tests were applied. The evaluation of reflow crack resistance was conducted by passing the sample through an IR reflow furnace set at a maximum temperature of 240 ° C. and maintaining this temperature for 20 seconds, and then cooling it by leaving it at room temperature. Repeated times. And the crack in a sample was observed visually and with the ultrasonic microscope. In all 10 samples, no crack occurred and ◯ indicates that one or more cracks occurred.
[0026]
The temperature cycle resistance is that the sample is left in a −55 ° C. atmosphere for 30 minutes and then left in a 125 ° C. atmosphere for 30 minutes. After 1000 cycles, an ultrasonic microscope is used to destroy peeling or cracks. Is not generated in all of the samples 10, and one or more is generated is ×.
As a result, reflow crack resistance: not occurred in all 10 samples (◯)
Temperature cycle resistance: not occurred in all 10 samples (○)
[0027]
As described above, the adhesive sheet of the present invention is excellent in heat resistance and moisture resistance, does not fly semiconductor elements during dicing, and has good pick-up properties.
[0028]
【The invention's effect】
The adhesive sheet of the present invention can be used as a dicing tape in the dicing process, and as an adhesive having excellent connection reliability in the bonding process between the semiconductor element and the support member, and the semiconductor element is mounted on the semiconductor mounting support member. It has heat resistance and moisture resistance necessary for the case, and is excellent in workability.
Moreover, the manufacturing method of the semiconductor chip (element) using the adhesive sheet of the present invention can simplify the manufacturing process, and the manufactured semiconductor device has a heat resistance necessary for mounting the semiconductor element on the semiconductor mounting support member. , Moisture resistance and workability.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of an example of an adhesive sheet according to the present invention.
FIG. 2 is a cross-sectional view of a state where grooves are formed in the adhesive sheet according to the present invention.
FIG. 3 is a view showing a state in which a semiconductor wafer is bonded to the adhesive sheet according to the present invention.
FIG. 4 is an explanatory diagram when the adhesive sheet according to the present invention is used in a semiconductor wafer dicing step and half-diced.
FIG. 5 is an explanatory diagram when the wafer is bent and broken into chips.
FIG. 6 is a diagram showing a picked-up semiconductor element and an adhesive layer.
FIG. 7 is a view showing a state in which a semiconductor element is thermocompression bonded to a semiconductor element mounting support member.
FIG. 8 is an external view of an alignment sheet and an adhesive sheet in which grooves and marks are formed in the shape of a chip.
FIG. 9 is a cross-sectional view of an example in which a groove is formed up to the middle of the adhesive layer, showing another example of the adhesive sheet.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Adhesive film 1 'Adhesive layer 2 Adhesive layer 4 Suction collet 5 Supporting member 10 for semiconductor element mounting, 100 Adhesive sheet 11, 110 Groove A Semiconductor wafer A1, A2, A3 Semiconductor element

Claims (7)

An adhesive that has an adhesive force between the wafer and the adhesive layer provided on the base film, which is greater than an adhesive force between the base film and the adhesive layer, and exhibits an adhesive force upon heating. The adhesive layer is attached to the upper surface of the adhesive layer, and the half- cut wafer is broken into chips without using a cutting blade to produce a chip with adhesive. A sheet,
Wherein the adhesive layer is in the vicinity of a lower portion of the portion where the half-cut of at least the wafer, the wafer is characterized in that the pre-groove is formed before being adhered to the upper surface of the adhesive layer adhered Sheet.   The adhesive sheet according to claim 1, further comprising an alignment unit for aligning with a wafer on the adhesive layer or the base film.   The groove of the adhesive layer is formed by printing the adhesive layer in a shape having a groove on the base film, or by removing the sheet-like adhesive into the groove shape by etching or punching with a mold. The adhesive sheet according to claim 1, wherein the adhesive sheet is formed of any one of the above.   The adhesive sheet according to any one of claims 1 to 3, wherein the groove is formed in the semiconductor element shape up to the middle of the film thickness of the base film.   The alignment means for aligning a wafer is a mark formed by etching or punching with a mold, or printing, an adhesive with a laser beam, or a modification of a base film. 4. The adhesive sheet according to any one of 4 above. In the method of manufacturing a semiconductor chip with an adhesive using an adhesive sheet,
The adhesive sheet is the adhesive sheet according to any one of claims 1 to 5, and when the predetermined position of the wafer is aligned with the alignment mark of the adhesive sheet, and then the wafer is half-cut into a semiconductor element shape. production method of the adhesive with the semiconductor chip, characterized in that the adhesive sheet of the vicinity of a lower portion of the half-cut to portions have Gana adhesive layer, or a groove of. 7. The method for manufacturing a semiconductor chip with an adhesive according to claim 6, wherein the processing for easily cutting a predetermined position of the wafer is performed by half cutting or modification by laser light .

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