JPWO2019171475A1 - Method for evaluating fluidity of resin composition, method for selecting resin composition, and method for manufacturing semiconductor device - Google Patents

Abstract

The present disclosure relates to a method for evaluating fluidity of a resin composition. This method comprises the steps of preparing a sample made of a resin composition, and measuring the shear elastic modulus of the sample at a temperature T while giving strain to the sample, so that the shear elastic modulus of the sample at the temperature T changes with time. And a step of grasping.

Description

  The present disclosure relates to a resin composition fluidity evaluation method, a resin composition selection method, and a semiconductor device manufacturing method.

  Along with the multi-functionalization of electronic devices such as smartphones and tablet PCs, a stacked MCP (Multi Chip Package) having a high capacity by stacking semiconductor elements in multiple stages has become widespread. A film adhesive is widely used for mounting semiconductor elements. However, in spite of the tendency toward multi-functionality, there is a limit to the data processing speed in the current connection method for semiconductor elements using wire bonds. On the other hand, since there is an increasing need for long-term use without charging, power saving is also being demanded. For the purpose of speeding up and power saving, a structure has been developed in which the entire semiconductor element is embedded with a die bond film to reduce the size of the element (for example, see FIG. 6 of Patent Document 1).

  In addition, electronic device devices having a new structure in which semiconductor elements are connected to each other by through electrodes instead of wire bonds have also been developed. In order to manufacture a semiconductor element having a through electrode, a temporary fixing material for temporarily fixing the semiconductor element to a support and processing it is necessary. Since this semiconductor element has a structure having innumerable electrodes on the surface, the temporary fixing material needs to have excellent fluidity to fill in the fine irregularities on the surface (Patent Document 2).

JP, 2017-168850, A International Publication No. 2017/191815

  In the step of embedding a semiconductor element in a die bond film made of a resin composition, the die bond film needs to be largely deformed. Alternatively, the resin composition forming the temporary fixing material is required to follow fine irregularities such as through electrodes. In the process of manufacturing a semiconductor device, it is difficult to predict in advance whether the resin composition to be used as an embedding material or a temporary fixing material has such deformability and followability, and it is necessary to actually use it. I often don't understand.

  Conventionally, fluidity is known as one of the indexes for evaluating the performance of a resin composition. For example, by measuring the shear viscosity of a resin composition using a rheometer, the fluidity of the resin composition may be grasped and the quality of the embedding property may be determined. However, the large deformation of the film as described above and the ability to follow fine irregularities include phenomena that cannot be explained only by the shear viscosity, and the conventional method can fully evaluate the suitability of the resin composition. There wasn't.

  The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a new method for evaluating the fluidity of a resin composition. The present disclosure aims to provide a method for selecting a resin composition and a method for manufacturing a semiconductor device, which include the evaluation method.

  The present disclosure provides a method for evaluating fluidity of a resin composition. This evaluation method comprises the steps of preparing a sample made of a resin composition and measuring the shear elastic modulus of the sample at a temperature T by applying strain to the sample to measure the shear elastic modulus of the sample at the temperature T with time. Recognizing the change. By grasping the temporal change of the shear elastic modulus at the temperature T, the characteristics of the resin composition (deformability and ability to follow fine irregularities) can be evaluated more accurately. This evaluation method is useful, for example, to judge whether the embedding property of the resin composition constituting the die bonding film and the temporary fixing material used in the manufacturing process of the semiconductor device is good or bad.

The Maxwell model stress relaxation equation may be used to quantify the change in shear modulus over time. That is, in the evaluation method according to the present disclosure, G (t) / G ₀ = 0.3679, which is derived using the following equation (1) of stress relaxation of Maxwell model, based on the measurement result of shear modulus of the sample. It may further include the step of reading the time (stress relaxation time τ).
G (t) = G ₀ × e ^{(−t / τ)} (1)
[In the formula (1), G (t) represents the shear elastic modulus at time t (sec), G ₀ represents the initial shear elastic modulus, t represents time (sec), and τ represents the stress relaxation time ( Seconds). ]
The numerical value “0.3679” in “G (t) / G ₀ = 0.3679” is calculated as follows.
When t = τ G (t) = G ₀ × e ^{(-1)
_{G (t) / G 0 =}} e (-1) = 0.3679

The present disclosure provides a method of selecting a resin composition. This selection method determines whether or not the step of performing the above-described fluidity evaluation method under the condition that the temperature T is 120 ° C. and the resin composition to be evaluated satisfy both the following conditions 1 and 2. The resin composition including the step and satisfying both conditions 1 and 2 is determined to be good.
Condition 1: The stress relaxation time at 120 ° C. is 12 seconds or less.
Condition 2: The initial shear elastic modulus at 120 ° C. is 35 kPa or less.

  The above selection method is useful, for example, for selecting the resin composition that constitutes the die bonding film, the temporary fixing material, and the like used in the manufacturing process of the semiconductor device.

  The semiconductor device manufacturing method according to the present disclosure uses the resin composition determined to be good by this selection method as an embedding material or a temporary fixing material.

  According to the present disclosure, a new method for evaluating the fluidity of a resin composition is provided. That is, according to this evaluation method, it is possible to quantitatively evaluate the characteristics of the film (for example, the deformability or the ability to follow fine irregularities), which was difficult to explain only by the shear viscosity. Further, according to the present disclosure, there are provided a method for selecting a resin composition and a method for manufacturing a semiconductor device, the method including the evaluation method.

FIG. 1 is a sectional view schematically showing an example of a semiconductor device. FIG. 2 is a schematic sectional view showing a series of steps for manufacturing the semiconductor device shown in FIG. FIG. 3 is a schematic cross-sectional view showing a series of steps for manufacturing the semiconductor device shown in FIG. FIG. 4 is a schematic cross-sectional view showing a series of steps for manufacturing the semiconductor device shown in FIG. FIG. 5 is a schematic cross-sectional view showing a series of steps for manufacturing the semiconductor device shown in FIG. FIG. 6 is a schematic cross-sectional view showing a series of steps for manufacturing the semiconductor device shown in FIG. FIG. 7 is a graph showing the change over time in the shear elastic modulus of the resin compositions according to Samples 1 to 14. FIG. 8 is a graph in which the characteristics (horizontal axis: shear elastic modulus [kPa], vertical axis: stress relaxation time τ (seconds)) of the resin compositions according to Samples 1 to 14 are plotted.

  Hereinafter, embodiments of the present disclosure will be described in detail, but the present invention is not limited to the following embodiments.

<Method for evaluating fluidity of resin composition>
The evaluation method according to the present embodiment is for evaluating the fluidity of a resin composition, and includes a step of preparing a sample composed of the resin composition, a step of applying strain to the sample and slipping the sample at a temperature T. Measuring the elastic modulus to grasp the temporal change of the shear elastic modulus of the sample at the temperature T.

The Maxwell model stress relaxation equation may be used to quantify the change in shear modulus over time. That is, based on the measurement result of the shear modulus of the sample, the time (stress relaxation time τ) at which G (t) / G ₀ = 0.3679 is obtained using the following equation (1) of stress relaxation of Maxwell model. You may read it. The initial shear elastic modulus (G ₀ ) of the sample can be obtained based on the measurement result of the shear elastic modulus of the sample.
G (t) = G ₀ × e ^{(−t / τ)} (1)
[In the formula (1), G (t) represents the shear elastic modulus at time t (sec), G ₀ represents the initial shear elastic modulus, t represents time (sec), and τ represents the stress relaxation time ( Seconds). ]

  The shear elastic modulus at the temperature T is preferably measured for, for example, at least 10 seconds, and the measurement time may be 30 to 1800 seconds or 60 to 600 seconds. From the viewpoint of stable measurement, the temperature T is preferably a specific temperature in the range of −50 to 400 ° C., and may be set according to the type and application of the resin composition to be evaluated. For example, when the type of the resin composition is a thermosetting resin composition and its application is a die bonding film or a temporary fixing material used for manufacturing a semiconductor device, for example, the temperature T is 30 to 300 ° C. , 50 to 200 ° C. or 80 to 150 ° C.

  The amount of strain applied to the sample is preferably in the range of 0.1 to 30% from the viewpoint of stable measurement, and can be set according to the type and application of the resin composition to be evaluated. Good. For example, when the type of the resin composition is a thermosetting resin composition and the use thereof is a die bonding film or a temporary fixing material used for manufacturing a semiconductor device, for example, the amount of strain is 0.5 to 25. %, Which may be 1 to 20% or 2 to 15%.

  The sample is preferably formed into a film. The thickness of the sample is preferably 10 to 1000 μm from the viewpoint of stable measurement, and may be set according to the type and application of the resin composition to be evaluated. For example, when the type of the resin composition is a thermosetting resin composition and its application is a die bonding film in which a semiconductor chip (for example, a controller chip) is embedded in the manufacture of a semiconductor device, or a temporary fixing material, The thickness of the film is 50 to 800 μm, and may be 80 to 600 μm or 100 to 500 μm. In addition, when the thickness of the film is too thin and it is difficult to measure the shear elastic modulus, a sample having an increased thickness may be prepared by stacking a plurality of sheets.

  According to the evaluation method of this embodiment, by grasping the temporal change in the shear elastic modulus at the temperature T, the characteristics of the resin composition can be evaluated more accurately. This evaluation method is useful for determining, for example, whether the embedding property of the resin composition forming the die bonding film used in the manufacturing process of the semiconductor device is good.

<Method of selecting resin composition>
The selection method according to the present embodiment is, for example, for selecting a resin composition that constitutes a die bonding film used in the manufacturing process of a semiconductor device. That is, this selection method is performed by performing the fluidity evaluation method according to the above embodiment under the condition that the temperature T is 120 ° C. and whether the resin composition to be evaluated satisfies the following conditions 1 and 2. And a step of determining whether the resin composition satisfies both conditions 1 and 2 is determined to be good.
Condition 1: The stress relaxation time at 120 ° C. is 12 seconds or less.
Condition 2: The initial shear elastic modulus at 120 ° C. is 35 kPa or less.

  Regarding the condition 1, the stress relaxation time at 120 ° C. of 12 seconds or less means that the shear elastic modulus decreases and the fluidity increases in a sufficiently short time after heat is applied to the resin composition. . This contributes to shortening the time required to manufacture the semiconductor device. From this viewpoint, the stress relaxation time at 120 ° C. is preferably 11 seconds or less, and may be 0.1 to 11 seconds.

  Regarding the condition 2, that the initial shear elastic modulus at 120 ° C. is 35 kPa or less means that the shear elastic modulus is low to some extent from the initial stage. The initial shear modulus at 120 ° C. is preferably 30 kPa or less, and may be 1 to 30 kPa.

  In the above-described embodiment, the case where the shear elastic modulus is measured under the condition that the temperature T is 120 ° C. has been described, but the temperature T may be changed depending on the temperature condition in which the resin composition is used in the manufacturing process of the semiconductor device. May be set, for example, 80 ° C. or 100 ° C., or 140 ° C.

<Semiconductor Device and Manufacturing Method Thereof>
The semiconductor device manufacturing method according to the present embodiment uses the resin composition determined to be good by the selection method according to the above embodiment as an embedding material. Hereinafter, an example of a semiconductor device and a method for manufacturing the same will be described with reference to the drawings.

  In the semiconductor device 100 shown in FIG. 1, the first semiconductor element Wa of the first stage is wire-bonded to the substrate 10 via the first wire 11. Further, the second semiconductor element Wb and the first wire 11 are subjected to a step of pressing the second semiconductor element Wb onto the first semiconductor element Wa via a film adhesive (resin composition). Is a semiconductor device which is embedded in a cured product 20 of a film adhesive. In the semiconductor device 100, the substrate 10 and the second semiconductor element Wb are electrically connected via the second wire 12, and the second semiconductor element Wb is sealed by the sealing material 40. In this embodiment, the film adhesive 20P (see FIG. 3) made of a thermosetting resin composition is a target for evaluating the fluidity. The film adhesive 20P becomes a cured product 20 by heat treatment.

  The substrate 10 has circuit patterns 10a and 10b on its surface. The first semiconductor element Wa is pressure-bonded onto the circuit pattern 10a via an adhesive 15. The first semiconductor element Wa is a controller chip for driving the semiconductor device 100. The thickness of the first semiconductor element Wa is, for example, 10 to 170 μm. The second semiconductor element Wb is mounted on the substrate 10 via a cured product 20 of a film adhesive so as to cover the first semiconductor element Wa and a part of the circuit pattern 10b. The thickness of the second semiconductor element Wb may be, for example, 20 to 400 μm.

  It is preferable that the cured product 20 of the film adhesive follows the steps caused by the first semiconductor element Wa and the circuit patterns 10a and 10b on the substrate 10. In other words, it is preferable that the interface between the substrate 10 and the first semiconductor element Wa arranged on the surface of the substrate 10 and the cured product 20 has no void.

  2 to 6 are schematic cross-sectional views showing a series of steps for manufacturing the semiconductor device 100. The semiconductor device manufacturing method according to the present embodiment includes a first wire bonding step of electrically connecting the first semiconductor element Wa to the substrate 10 via the first wire 11, and a second semiconductor element Wb. A step of preparing a semiconductor element 30 with an adhesive having a film adhesive 20P attached to one surface thereof, a die bonding step of adhering the semiconductor element 30 with an adhesive to the substrate 10, and a second semiconductor element Wb A second wire bonding step of electrically connecting to the substrate 10 via the second wire 12.

  As shown in FIG. 2, the first semiconductor element Wa having the adhesive 15 is pressure-bonded onto the circuit pattern 10 a on the substrate 10, and the circuit pattern 10 a and the first semiconductor element Wa on the substrate 10 are connected via the first wire 11. The semiconductor element Wa is electrically connected by bonding (first wire bonding step).

  As shown in FIG. 3, the second semiconductor element Wb and the semiconductor element 30 with the adhesive on one surface thereof and the film adhesive 20P are separately prepared (step of preparing the semiconductor element with the adhesive). The adhesive-attached semiconductor element 30 is obtained by laminating a die bonding film (the same resin composition as the film adhesive 20P) and a dicing film in this order on one side of a semiconductor wafer, and performing a dicing step and a pickup step. Good.

  Next, as shown in FIGS. 4 and 5, the semiconductor element 30 with an adhesive is pressure-bonded to the substrate 10 so that the first wire 11 and the first semiconductor element Wa are covered with the film adhesive 20P ( Die-bonding process). In the die bonding step, it is preferable that the film adhesive 20P is pressure-bonded under the conditions of 80 to 180 ° C. and 0.01 to 0.50 MPa for 0.5 to 3.0 seconds. By pressing and heating the film adhesive 20P under conditions of 60 to 175 ° C. and 0.3 to 0.7 MPa for 5 minutes or more, the film adhesive 20P is cured and becomes a cured product 20.

  Next, as shown in FIG. 6, the substrate 10 and the second semiconductor element Wb are electrically connected via the second wire 12 (second wire bonding step). Then, the circuit pattern 10b, the second wire 12, and the second semiconductor element Wb are sealed with the sealing material 40. The semiconductor device 100 can be manufactured through such steps.

  In the above embodiment, the semiconductor device in which the first wire 11 and the first semiconductor element Wa are embedded has been illustrated, but a wire-embedded semiconductor in which at least a part of the first wire 11 is embedded. It may be a device.

Further, in the above-described embodiment, the semiconductor device using the embedding material (die bond film), which is one of the objects of fluidity evaluation, and the manufacturing method thereof have been described. However, the present disclosure discloses a temporary fixing material (resin film for temporary fixing). ) May be an evaluation target. Then, the semiconductor device may be manufactured using the temporary fixing material determined to be good by the selection method of the present disclosure. Patent Document 2 describes in detail the specific configuration and usage of the temporary fixing material. The method for manufacturing a semiconductor device using the temporary fixing resin film includes, for example, the following steps.
(A) A step of temporarily fixing a semiconductor wafer having a circuit-formed surface and a support through a temporary fixing resin film.
(B) A step of processing a semiconductor wafer temporarily fixed to a support.
(C) A step of separating the processed semiconductor wafer from the support and the temporary fixing resin film.
(D) A step of obtaining a semiconductor element by dividing the separated semiconductor wafer into pieces.
(E) A step of mounting a semiconductor element on a wiring board or the like.
In step (a), the circuit is temporarily fixed so that the surface on which the circuit is formed (the surface having irregularities) is in contact with the temporary fixing resin film. When the temporary fixing resin film is made of a thermosetting resin composition, a step of thermosetting the temporary fixing resin film may be performed between the step (a) and the step (b).

  Hereinafter, the present disclosure will be described more specifically with reference to examples. However, the present invention is not limited to these examples.

[Production of laminated body]
A total of 14 types of thermosetting resin compositions for die bonding or temporary fixing materials (flowability evaluation targets) were prepared. After coating each resin composition on the release treated surface of a polyethylene terephthalate film (PET film, Teijin DuPont Films Co., Ltd., A31, thickness 38 μm), it was dried by heating at 90 ° C. for 5 minutes and at 130 ° C. for 5 minutes. . As a result, a resin layer (thickness: 30 μm) was formed on the PET film. A total of 14 kinds of laminates (PET film / resin composition / PET film) were produced by further bonding another PET film as a protective film on this resin layer.

  A sample was prepared from each of the laminates prepared as described above, the shear elastic modulus was measured, and the stress relaxation time (τ) was measured. From these results, the fluidity of the thermosetting resin composition (specifically, the step embedding property) was evaluated.

[Sample preparation]
As described below, the dynamic viscoelasticity device ARES (manufactured by TA Instruments Co., Ltd.) was used for the measurement of the shear elastic modulus and the stress relaxation time. Since the thickness of the resin layer cannot be measured when it is 30 μm, a resin layer having a thickness of 30 μm is roll-laminated at 80 ° C. and six sheets are superposed, followed by punching to obtain a sample (180 μm thick, 10 mm square). .

[Measurement of elastic modulus]
A circular aluminum plate jig having a diameter of 8 mm was set on a dynamic viscoelastic device ARES (manufactured by TA Instruments Co., Ltd.), and a sample was set on the jig. Then, it was maintained at a temperature of 120 ° C. with a strain of 10%, and the change in stress was recorded.

[Calculation of initial shear modulus (G ₀ )]
From the measurement result of the shear elastic modulus, the shear elastic modulus immediately after the strain was applied was defined as the initial shear elastic modulus (G ₀ ). Table 1 and Table 2 show the results of 14 kinds of samples in total.

[Calculation of stress relaxation time (τ)]
The stress relaxation time (τ) at which G (t) / G ₀ = 0.3679 was obtained from the measurement result of the shear elastic modulus and the above formula (1). Table 1 and Table 2 show the results of 14 kinds of samples in total. FIG. 7 is a graph showing the change over time in the shear elastic modulus of the resin compositions according to Samples 1 to 14.

[Step embedding]
The step embedding property (fluidity) of the resin composition was evaluated as follows. A semiconductor adhesive-attached semiconductor chip was obtained by bonding a film adhesive (30 μm thick) made of a resin composition to the surface of a 625 μm thick silicon mirror wafer (6 inches) by roll lamination at 80 ° C. On the other hand, a plurality of grooves (width 40 μm, depth 40 μm) were formed at intervals of 100 μm on the surface of a 725 μm thick silicon mirror wafer (8 inches) by blade dicing.

  A silicon mirror wafer (thickness: 725 μm) was placed on a stage of a vacuum laminator (LM-50X50-S, manufactured by NPC Co., Ltd.) such that the surface on which the groove was formed was the upper surface. The semiconductor chip with the adhesive was placed thereon so that the side with the adhesive faced down. Under a condition of 15 mbar, heating and pressurization was performed at a temperature of 120 ° C. and a pressure of 0.1 MPa for 2 minutes, and vacuum lamination was performed.

After vacuum lamination, the degree to which the groove was filled with the resin composition was observed by a digital microscope and evaluated. That is, the laminate after vacuum lamination was cast with an epoxy resin, the cast resin was cured, and then the cross section was exposed by polishing. The cross section was observed with a digital microscope (VHX-5000 manufactured by Aense Co., Ltd.). The evaluation criteria for embeddability were as follows.
A: It is recognized that the groove is completely filled with the resin composition.
B: 70% or more of the sectional area of the groove is filled with the resin composition.
C: The ratio of the cross-sectional area of the groove filled with the resin composition is less than 70%.

As shown in Table 1, the resin compositions according to Samples 1 to 6 had an initial shear modulus (G ₀ ) of 35 kPa or less (condition 2) and a stress relaxation time (τ) of 12 seconds or less (condition 1). ), And the step embedding property was excellent. On the other hand, as shown in Table 2, the resin compositions (Samples 7, 12, and 13) that do not satisfy both Condition 1 and Condition 2 have insufficient step embedding properties, and the resin composition of Condition 1 and Condition 2 The resin composition (Samples 8-11 and 14) that does not satisfy one of them also had insufficient step embedding properties. FIG. 8 is a graph in which the characteristics (horizontal axis: initial shear modulus [kPa], vertical axis: stress relaxation time (seconds)) of the resin compositions of Samples 1 to 14 are plotted. As shown in this graph, the step embedding property depends not only on the initial shear modulus but also on the stress relaxation time.

  According to the present disclosure, there are provided a new method for evaluating the fluidity of a resin composition, a method for selecting a resin composition including this method, and a method for manufacturing a semiconductor device.

10 ... Substrate, 10a, 10b ... Circuit pattern, 11 ... First wire, 12 ... Second wire, 15 ... Adhesive agent, 20 ... Cured product of film adhesive, 20P ... Film adhesive (resin composition ), 30 ... Semiconductor element with adhesive, 40 ... Encapsulating material, 100 ... Semiconductor device, Wa ... First semiconductor element, Wb ... Second semiconductor element

Claims (11)

A method for evaluating fluidity of a resin composition,
A step of preparing a sample composed of the resin composition,
Grasping a temporal change of the shear elastic modulus of the sample at the temperature T by applying strain to the sample and measuring the shear elastic modulus of the sample at a temperature T;
And a liquidity evaluation method including. Based on the measurement result of the shear elastic modulus of the sample, a step of reading a time t at which G (t) / G ₀ = 0.3679, which is derived using the following equation (1) of stress relaxation of Maxwell model, is further read. The liquidity evaluation method according to claim 1, comprising.
G (t) = G ₀ × e ^{(−t / τ)} (1)
[In the formula (1), G (t) represents the shear elastic modulus at time t (sec), G ₀ represents the initial shear elastic modulus, t represents time (sec), and τ represents the stress relaxation time ( Seconds). ]   The fluidity evaluation method according to claim 1, further comprising a step of grasping an initial shear elastic modulus based on a measurement result of the shear elastic modulus of the sample.   The fluidity evaluation method according to claim 1, wherein the shear elastic modulus of the sample is measured for at least 60 seconds.   The fluidity evaluation method according to any one of claims 1 to 4, wherein the temperature T is a specific temperature in the range of -50 to 400 ° C.   The fluidity evaluation method according to any one of claims 1 to 5, wherein the amount of strain applied to the sample is 1 to 30%.   The fluidity evaluation method according to claim 1, wherein the sample has a thickness of 0.01 to 1 mm.   The fluidity evaluation method according to claim 1, wherein the resin composition is a material used for manufacturing a semiconductor device.   The fluidity evaluation method according to claim 8, wherein the resin composition is a filling material. Carrying out the fluidity evaluation method according to any one of claims 1 to 9 under the condition that the temperature T is 120 ° C;
A step of determining whether the resin composition to be evaluated satisfies both of the following conditions 1 and 2,
Including,
A method for selecting a resin composition, wherein a resin composition satisfying both the conditions 1 and 2 is judged to be good.
Condition 1: The stress relaxation time at 120 ° C. is 12 seconds or less.
Condition 2: The initial shear elastic modulus at 120 ° C. is 35 kPa or less.   A method for manufacturing a semiconductor device, wherein the resin composition determined to be good by the screening method according to claim 10 is used as an embedding material or a temporary fixing material.