JP7149099B2 - Semiconductor device manufacturing method - Google Patents

Description

The present technology relates to a method for manufacturing a semiconductor device.

With a conventional general liquid underfill material, it is difficult to mount a thin semiconductor chip or perform 3D mounting. For this reason, for example, a pre-applied underfill film (PUF) is used, in which an underfill film is attached to a substrate before metal bonding or pressure bonding is performed between semiconductor IC (Integrated Circuit) electrodes and substrate electrodes. is being considered for use.

A mounting method using a pre-supply type underfill film is performed, for example, as follows (see, for example, Patent Document 1).

Step 1: An underfill film is attached to a wafer and diced to obtain chips with an underfill film.
Step 2: Align the chip with the underfill film and the electronic component.
Step 3: After heating the chip with the underfill film to such an extent that the underfill film becomes fluid but does not undergo main curing, the chip with the underfill film and the electronic component are thermocompression bonded.

In such a mounting method, as a method for improving the production takt time per chip (UPH: Unit Per Hour), for example, multi-heading, batch crimping, etc. are conceivable. However, the use of multiple heads increases the price of the device and increases the cost per chip. In batch crimping, it is difficult to control the temperature using a bonder (heat tool), so the rate of temperature rise varies depending on the position of the chip. There is

The viscosity of the underfill film is also an important factor in improving the production takt time. If the viscosity of the underfill film is too low, voids may occur during thermocompression bonding. Further, if the viscosity of the underfill film is too high, when the underfill film is attached to the wafer, voids may be mixed in due to insufficient pressing.

Therefore, in the conventional mounting method, a heating time (holding time) is required to adjust the viscosity of the underfill film for each chip in order to suppress voids before thermocompression bonding, as in step 3 described above. rice field. This heating time was one of the obstacles to improving the production takt time.

Therefore, there is a demand for a method that enables high-quality mounting in a short period of time, specifically, a method that provides a semiconductor device with a short production takt time per chip and good connectivity and void exclusion.

JP 2016-146412 A

The present technology has been proposed in view of such conventional circumstances, and provides a method of manufacturing a semiconductor device by which a high-quality semiconductor device can be obtained in a short time.

A method for manufacturing a semiconductor device according to the present technology includes a step (A) of attaching an underfill film on a wafer, a step (B) of dicing the wafer to which the underfill film is attached, and a step (B) of dicing the wafer to which the underfill film is attached. A step (C) of connecting the chip with the underfill film and the electronic component, which are singulated from the wafer, and the underfill film is connected after the step (A) and before the wafer is singulated. and a step (D) of heating the bonded wafer so that the minimum melt viscosity of the underfill film is less than 100000 Pa·s.

According to the present technology, a high-quality semiconductor device can be obtained in a short time.

FIG. 1 is a graph showing an example of the time transition of the viscosity of the underfill film in the semiconductor device manufacturing method according to the present embodiment and the conventional semiconductor device manufacturing method. FIG. 2 is a graph showing an example of the melt viscosity curve of the underfill film according to this embodiment. FIG. 3 is a perspective view schematically showing an example of a process of attaching an underfill film onto a wafer. FIG. 4 is a perspective view schematically showing an example of a process of dicing a wafer. FIG. 5 is a perspective view schematically showing an example of the process of picking up a semiconductor chip. FIG. 6 is a cross-sectional view schematically showing a semiconductor chip and an electronic component before mounting. FIG. 7 is a cross-sectional view schematically showing the semiconductor chip and the electronic component after thermocompression bonding.

A method for manufacturing a semiconductor device according to the present technology includes a step (A) of attaching an underfill film on a wafer, a step (B) of dicing the wafer to which the underfill film is attached, and a step (B) of dicing the wafer to which the underfill film is attached. a step (C) of connecting the chip with the underfill film and the electronic component, which are singulated from the wafer, and after the step (A) until the wafer to which the underfill film is attached is singulated. and (D) heating the wafer to which the underfill film is attached so that the minimum melt viscosity of the underfill film is less than 100000 Pa·s.

FIG. 1 is a graph showing an example of the time transition of the viscosity of an underfill film in a method of manufacturing a semiconductor device. The horizontal axis represents time (each step after step (A)), and the vertical axis represents the viscosity of the underfill film. In FIG. 1, graph (1) is for the method of the present technology, and graph (2) is for the conventional method. Broken lines in graphs (1) and (2) indicate that the corresponding step is not performed. In graph (1), in step (D), the resin of the underfill film reaches the gelation point, the reaction system changes from a liquid state to a rubber state, and further, the reaction starts to change from a rubber state to a glass state. can be considered as a stage. In graph (1), in step (C), when the resin of the underfill film changes from a glassy state to a rubbery state, the graph drops slightly, and when the rubbery state changes to a glassy state again, the graph rises. be done.

FIG. 2 is a graph showing an example of a melt viscosity curve of an underfill film. In this manufacturing method, from after the step (A) (for example, the viscosity state of A in FIG. 2) to before the wafer to which the underfill film is attached is singulated (diced), the As indicated by the arrow in B, there is a step (D) of increasing the viscosity of the underfill film. As a result, as indicated by C in FIG. 2, the viscosity of the underfill film is increased compared to before heating, and the time required for adjusting the viscosity of the underfill film for each chip, which was conventionally required, can be omitted. In addition, since the viscosity of the underfill film is adjusted after the underfill film is attached to the wafer, it is possible to suppress the inclusion of voids due to insufficient pressing when the underfill film is attached to the wafer. Furthermore, since the viscosity of the underfill film is adjusted before thermocompression bonding, it is possible to suppress the generation of voids due to the underfill film having too low viscosity during thermocompression bonding. Therefore, in the method for manufacturing a semiconductor device according to the present technology, a high-quality semiconductor device can be obtained in a short time.

A specific example of the method for manufacturing a semiconductor device according to the present technology will be described below. An example of a method for manufacturing a semiconductor device includes the above-described steps (A), (D), (B), and (C) in this order.

[Step (A1)]
In step (A), an underfill film is attached onto the wafer. For example, as shown in FIG. 3, the wafer 2 is fixed by a jig 3 having a ring-shaped or frame-shaped frame having a diameter larger than that of the wafer 2, and the underfill film 1 is applied on the wafer at a predetermined temperature. Paste (laminate). The application temperature is preferably 25° C. to 100° C., more preferably 40° C. to 80° C., from the viewpoint of void exclusion.

A large number of ICs (Integrated Circuits) are built into the wafer 2 . On the bonding surface of the wafer 2 (the surface to which the underfill film 1 is attached), electrodes with solder for connection called bumps are formed for each semiconductor chip divided by the scribe lines. This soldered electrode is formed by soldering an electrode made of copper or the like, for example.

The underfill film 1 protects and fixes the wafer 2 during dicing and functions as a dicing tape that holds the wafer 2 during pickup. The underfill film 1 can be formed, for example, from an adhesive composition (underfill material) containing an acrylic polymer, an epoxy resin, a curing agent, a curing accelerator, and an inorganic filler.

The acrylic polymer is preferably an acrylic rubber polymer having an epoxy group and an amide group from the viewpoint of connectivity and the like. The lower limit of the weight average molecular weight of the acrylic polymer is, for example, preferably 5.0×10 ³ or more, more preferably 1.0×10 ⁴ or more. Moreover, the upper limit of the weight average molecular weight of the acrylic polymer is, for example, preferably 10 ⁶ or less, more preferably 7.0×10 ⁵ or less. One type of acrylic polymer may be used alone, or two or more types may be used in combination. The content of the acrylic polymer in the underfill material is preferably 5-30% by mass, more preferably 10-20% by mass.

Examples of epoxy resins include dicyclopentadiene type epoxy resins, glycidyl ether type epoxy resins, glycidylamine type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol S type epoxy resins, spirocyclic epoxy resins, Naphthalene type epoxy resin, biphenyl type epoxy resin, terpene type epoxy resin, tetrabromobisphenol A type epoxy resin, cresol novolak type epoxy resin, phenol novolac type epoxy resin, α-naphthol novolak type epoxy resin, brominated phenol novolac type epoxy resin etc. can be mentioned. As the epoxy resin, bisphenol A type epoxy resin and naphthalene type epoxy resin are preferable. The epoxy resin preferably has two or more epoxy groups. An epoxy resin may be used individually by 1 type, and may use 2 or more types together. The content of the epoxy resin in the underfill material is preferably 10-40% by mass, more preferably 23-32% by mass.

As curing agents (epoxy resin curing agents), phenols, imidazoles, acid anhydrides, amines, hydrazides, polymercaptans, Lewis acid-amine complexes and the like can be used. Among these, a phenol compound is preferred because it provides a high cross-linking density. Phenol compounds include phenol novolak compounds, cresol novolak compounds, aromatic hydrocarbon formaldehyde resin-modified phenol compounds, dicyclopentadiene phenol addition type compounds, and phenol aralkyl compounds. Among phenol compounds, phenol novolak compounds are preferred from the viewpoint of heat resistance. A single curing agent may be used alone, or two or more curing agents may be used in combination. The content of the curing agent in the underfill material is preferably 1 to 20% by mass, more preferably 10 to 12% by mass.

Curing accelerators include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-ethyl-4-methylimidazole, 1,8-diazabicyclo(5,4,0)undecene-7 salt (DBU salt ), tertiary amines such as 2-(dimethylaminomethyl)phenol, phosphines such as triphenylphosphine, and metal compounds such as tin octylate. A hardening accelerator may be used individually by 1 type, and may use 2 or more types together. The content of the curing accelerator in the underfill material is preferably 0.1 to 10% by mass, more preferably 1 to 2% by mass.

The inorganic filler is used for the purpose of adjusting the fluidity of the resin layer during pressure bonding. Inorganic fillers that can be used include silica, talc, titanium oxide, calcium carbonate, magnesium oxide, and the like. An inorganic filler may be used individually by 1 type, and may use 2 or more types together. The content of the inorganic filler in the underfill material is preferably 25-60% by mass, more preferably 35-47% by mass.

In addition, the adhesive composition may further contain components other than the components described above, such as organic peroxides and solvents, as long as the effects of the present technology are not impaired.

The underfill film is obtained, for example, by preparing the adhesive composition described above, applying the adhesive composition onto a release-treated substrate using a bar coater, and drying.

[Step (D)]
In step (D), the wafer to which the underfill film is attached is heated so that the minimum melt viscosity of the underfill film is less than 100000 Pa·s. If the underfill film has a minimum melt viscosity of 100,000 Pa·s or more, it tends to be difficult to obtain good connectivity during thermocompression bonding in step (C), which will be described later. The minimum melt viscosity of the underfill film is preferably adjusted to more than 3000 Pa·s and less than 100000 Pa·s, more preferably 20000 to 50000 Pa·s. By adjusting the minimum melt viscosity of the underfill film to over 3000 Pa·s, it is possible to suppress the generation of voids during thermocompression bonding.

Heating in the step (D) is performed under conditions of a predetermined temperature, pressure, and time at which the underfill film becomes fluid but does not undergo main curing, for example, by heating means (e.g., hot plate, heating bonder). preferably. The heating temperature is preferably equal to or higher than the lowest melt viscosity attainment temperature of the underfill film. For example, when an underfill film made of the adhesive composition described above is used, the heating temperature is preferably 100 to 200.degree. The heating time is preferably 30 minutes or less, more preferably 5 minutes or less, even more preferably 30 seconds or less, still more preferably 5 seconds or less, and particularly preferably 2 seconds or less, from the viewpoint of shortening the production tact. Preferred heating conditions are, for example, 200° C. for 2 seconds or less, 180° C. for 5 seconds or less, 130° C. for 5 minutes or less, and 100° C. for 30 minutes or less.

[Step (B)]
In step (B), the wafer to which the underfill film is attached is diced. For example, as shown in FIG. 4, the blade 4 is pressed along the scribe line to cut the wafer 2 and divide it into individual semiconductor chips (individualization).

[Step (C)]
In the step (C), the chip with the underfill film, which is obtained by singulating the wafer with the underfill film attached, and the electronic component are connected. For example, as shown in FIG. 5, the semiconductor chip 5 is held by the underfill film 1 and picked up.

Next, as shown in FIG. 6, for example, the electrodes 7 of the chip with the underfill film and the electrodes 12 of the bottom chip 10 as an electronic component are aligned so as to face each other.

Then, the solder 22 of the electrode 7 is melted by thermocompression to form a metallic bond, and the underfill film 1 is completely cured. Thereby, for example, as shown in FIG. 7, the electrodes 7 of the semiconductor chip 5 and the electrodes 12 of the bottom chip 10 can be electrically and mechanically connected. The temperature condition for thermocompression bonding is preferably, for example, 150°C or higher and 300°C or lower, more preferably 230 to 280°C. The pressure condition for thermocompression bonding is preferably, for example, 90 N or less, more preferably 70 N or less. The time condition for thermocompression bonding is, for example, preferably 0.1 seconds or more and 60 seconds or less, and may be 5 to 20 seconds.

As described above, in the present manufacturing method, after the step (A), before the wafers with the underfill film attached are separated into individual pieces, the wafer with the underfill film attached is heated to obtain an underfill film. A high-quality semiconductor device can be obtained in a short time by increasing the viscosity of the fill film.

Also, the above example is a method having step (D) before step (B), but the method is not limited to this example. For example, as another example, in step (B), step (D) may be performed before singulating the wafer to which the underfill film is attached. This method also makes it possible to obtain a high-quality semiconductor device in a short period of time.

Further, the above-described step (C) has been described as not including heating (holding) the chip with the underfill film with a heat tool before thermocompression bonding. may be provided.

In addition, the present manufacturing method is not limited to the example in which the semiconductor chips are crimp-mounted one by one as described above. It can also be applied when crimping.

Examples of the present technology will be described below. The present technology is not limited to these examples.

[Underfill film]
An underfill film was produced using the following materials.
Acrylic rubber: SG-80H (manufactured by Nagasemtex Co., Ltd.), epoxy value 0.07 eq/kg, Mw; 35×10 ⁴
Epoxy resin: EXA-4850-1000 (manufactured by DIC), epoxy equivalent 350 g/eq
Epoxy resin: HP-4710 (manufactured by DIC), epoxy equivalent 170 g/eq
Curing agent: TD-2131 (manufactured by DIC), phenol novolak resin, softening point 78-82°C
Curing accelerator: U-CAT 3513N (manufactured by San-Apro)
Inorganic filler: SC1050 (manufactured by Admatechs), spherical silica Inorganic filler: Aerosil R805 (manufactured by Aerosil), hydrophobic fumed silica

Each component was weighed and mixed so that the compounding ratio (parts by mass) shown in Table 1 was obtained to obtain an adhesive composition. This adhesive composition was applied to release-treated PET using a bar coater and dried in an oven at 80° C. for 3 minutes. Thus, an underfill film having a thickness of 20 μm was produced.

[Example 1]
[Fabrication of semiconductor device]
[Step (A)]
The underfill film was adhered onto a 12-inch wafer (1800 shots of chips) and laminated under the conditions of 65° C., 30 seconds, and 0.1 MPa using a vacuum laminator (manufactured by Meiki Co., Ltd.). As a result, a wafer with an underfill film was obtained.

[Step (D)]
The wafer attached with the underfill film was heated on a hot plate at 200° C. for 2 seconds.

[Step (B)]
The wafer to which the heated underfill film was attached was diced (divided into pieces) to obtain chips with the underfill film. This chip with underfill film has the following chips.
Size: 6.0 x 6.0 mm square, thickness: 0.2 μm
Bump specifications: Cu (thickness 10 μm) + Ni (thickness 2 μm) + solder (thickness 5 μm), number of bumps: 20443 pins/15 μmφ/40 μm pitch

[Step (C)]
A chip with an underfill film is attached to a bottom chip (size: 8.0 × 8.0 mm square, thickness: 0.2 μm, bump specifications: the above-mentioned underfill film using a flip chip bonder (FCB3, manufactured by Panasonic Corporation). (similar to the bumps of the attached chip), and thermal compression bonding was performed under the conditions of a peak temperature of 250° C., 10 seconds, and 70 N. Thus, a semiconductor device for evaluation was produced.

[Example 2]
Except for changing the heating time in step (D) to 1 second and heating at 200° C. for 1 second after aligning the chip with the underfill film to the bottom chip and before thermocompression bonding in step (C). produced a semiconductor device in the same manner as in Example 1.

[Example 3]
A semiconductor device was fabricated in the same manner as in Example 1, except that in step (D), the heating temperature was changed to 180° C. and the heating time was changed to 5 seconds.

[Comparative Example 1]
Example 1 except that the step (D) was not performed, and that the chip with the underfill film was aligned with the bottom chip in the step (C) and then heated at 200° C. for 2 seconds before thermocompression bonding. A semiconductor device was fabricated in the same manner as described above.

[Comparative Example 2]
A semiconductor device was fabricated in the same manner as in Example 1, except that the heating time was changed to 5 seconds in step (D).

[Comparative Example 3]
A semiconductor device was fabricated in the same manner as in Example 1, except that the step (D) was not performed.

<Minimum melt viscosity of underfill film>
Table 2 shows the minimum melt viscosities of the underfill films after heating in step (D) for Examples 1 to 3 and Comparative Example 2. In Comparative Examples 1 and 3, since the step (D) was not performed, Table 2 shows the minimum melt viscosity of the underfill film measured after lamination in the step (A). The temperature at which the underfill film reached the lowest melt viscosity was 150°C. The minimum melt viscosity and the temperature at which the minimum melt viscosity of the underfill film was reached were measured using a rheometer (ARES manufactured by TA) under the conditions of 5° C./min and 1 Hz.

<Evaluation of Connectivity>
A connection (daisy chain connection) state between chips of the semiconductor device was checked with a probe tester. A case where the connection of all conduction paths could be confirmed was evaluated as OK, and a case where even one connection could not be made was evaluated as NG. Table 2 shows the results.

<Void evaluation>
The presence or absence of voids between chips of the semiconductor device was non-destructively inspected using SAT (Scanning Acoustic Tomograph). A case where voids were not generated was evaluated as OK, and a case where voids were generated was evaluated as NG. Table 2 shows the results.

<Evaluation of UPH>
The sum of the heating (wafer contact) time in step (D) and the heating (chip contact) time before thermocompression bonding in step (C) required for one wafer (= 1800 chips to be singulated) We evaluated the production takt based on Based on Comparative Example 1 (conventional method), the sum of the wafer contact time and the chip contact time required for one wafer was short and was evaluated as OK, and the others were evaluated as NG. Table 2 shows the results.

In Example 1, the wafer contact time was 2 seconds and the chip contact time was 0 seconds. Therefore, in Example 1, the total time required for wafer contact and chip contact for one wafer was 2 seconds.

In Example 2, the wafer contact time was 1 second and the chip contact time was 1 second. Therefore, in Example 2, the total of the wafer contact time (2 seconds) required for one wafer and the chip contact time (1 second×1800 chips=1800 seconds) was about 30 minutes.

In Example 3, the wafer contact time was 5 seconds and the chip contact time was 0 seconds. Therefore, in Example 3, the total time required for wafer contact and chip contact for one wafer was 5 seconds.

In Comparative Example 1, the wafer contact time was 0 seconds and the chip contact time was 2 seconds. Therefore, in Comparative Example 1, the sum of the wafer contact time (0 seconds) and the chip contact time (2 seconds×1800 chips=3600 seconds) required for one wafer was about 60 minutes.

In Comparative Example 2, the wafer contact time was 5 seconds and the chip contact time was 0 seconds. Therefore, in Comparative Example 2, the sum of the wafer contact time and the chip contact time required for one wafer was 5 seconds.

In Comparative Example 3, the wafer contact time was 0 seconds and the chip contact time was 0 seconds. Therefore, in Comparative Example 3, the sum of the wafer contact time and the chip contact time required for one wafer was 0 seconds.

<Comprehensive evaluation>
Among the evaluations of connectivity, voids, and UHP described above, the case where all were OK was evaluated as OK, and the others were evaluated as NG. Table 2 shows the results.

In Comparative Example 1, the step (D) of heating the underfill film so that the minimum melt viscosity of the underfill film was less than 100000 Pa·s was not performed after the step (A) and before the wafers were singulated. The UPH rating was not good. In Comparative Example 2, since the underfill film was not heated so that the minimum melt viscosity of the underfill film was less than 100000 Pa·s in the step (D), the connectivity was not good. In Comparative Example 3, since the step (D) was not performed and the holding time was not provided in the step (C), the void exclusion property was not good.

In Examples 1 to 3, since the underfill film was heated so that the minimum melt viscosity of the underfill film was less than 100000 Pa s before the wafer was singulated after the step (A), connectivity and void exclusion , UPH evaluation was good.

1 underfill film 2 wafer 3 jig 4 blade 5 semiconductor chip 6 semiconductor 7 electrode 8 solder 9 cured underfill film 10 bottom chip 11 substrate 12 electrode

Claims (8)

A step (A) of attaching an underfill film on the wafer;
a step (B) of dicing the wafer to which the underfill film is attached;
A step (C) of thermocompression bonding the chip with the underfill film, which is obtained by singulating the wafer to which the underfill film is attached, and the electronic component;
After the step (A) and before the wafers are singulated, the wafers to which the underfill film is attached are treated so that the minimum melt viscosity of the underfill film is less than 100000 Pa s. and a heating step (D) ,
In the step (D), the method of manufacturing a semiconductor device, wherein the wafer having the underfill film attached is heated at 100 to 200° C. for 30 seconds or less . 2. The method of manufacturing a semiconductor device according to claim 1, wherein said underfill film comprises an adhesive composition containing an acrylic polymer, an epoxy resin, an epoxy curing agent, a curing accelerator, and an inorganic filler. The adhesive composition has an acrylic polymer content of 10 to 20% by mass, an epoxy resin content of 23 to 32% by mass, and an epoxy curing agent content of 10 to 12% by mass. 3. The method of manufacturing a semiconductor device according to claim 2, wherein the content of the curing accelerator is 1 to 2% by mass, and the content of the inorganic filler is 35 to 47% by mass. 4. The method of manufacturing a semiconductor device according to claim 1, wherein in the step (D), the underfill film is heated so that the minimum melt viscosity of the underfill film is more than 3000 Pa.s and less than 100000 Pa.s. 2. The underfill film according to claim 1, comprising an adhesive composition containing an acrylic rubber polymer having an epoxy group and an amide group, an epoxy resin, an epoxy curing agent, a curing accelerator, and an inorganic filler. and a method for manufacturing a semiconductor device. 6. The method of manufacturing a semiconductor device according to claim 1, wherein the step (C) does not include heating the chip with the underfill film before the thermocompression bonding. 7. The method of manufacturing a semiconductor device according to claim 1, comprising the step (A), the step (D), the step (B), and the step (C) in this order. . A step (A) of attaching an underfill film on the wafer;
a step (B) of dicing the wafer to which the underfill film is attached;
A step (C) of thermocompression bonding the chip with the underfill film, which is obtained by singulating the wafer to which the underfill film is attached, and the electronic component;
After the step (A) and before the wafers are singulated, the wafers to which the underfill films are attached are separated from each other by the underfill films so that the viscosity of the underfill films increases. and (D) heating so that the minimum melt viscosity is less than 100000 Pa·s.

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