JP6414373B1 - 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 the fluidity of a resin composition. This method includes the steps of preparing a sample comprising a resin composition, and measuring the shear modulus of the sample at temperature T by applying strain to the sample and measuring the shear modulus of the sample at temperature T. And the process 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.

  As electronic devices such as smartphones and tablet PCs become multifunctional, stacked MCPs (Multi Chip Packages), which have a high capacity by stacking semiconductor elements in multiple stages, have become widespread. Film adhesives are widely used for mounting semiconductor elements. However, despite the trend toward multi-functionality, there is a limit to the data processing speed in the current semiconductor device connection method using wire bonds. On the other hand, since there is an increasing need to use the battery for a longer time without charging, power saving is being demanded. For the purpose of speeding up and saving power, a structure has been developed in which a semiconductor element is entirely embedded with a die bond film to reduce the size of the element (see, for example, FIG. 6 of Patent Document 1).

  In addition, electronic device apparatuses having a new structure in which semiconductor elements are connected to each other by a through electrode instead of a wire bond have been developed. In order to manufacture a semiconductor element having a through electrode, a temporary fixing material for temporarily fixing and processing the semiconductor element on a support is required. Since this semiconductor element has a structure having an infinite number of electrodes on the surface, the temporary fixing material needs excellent fluidity to embed 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 greatly deformed. Or it is calculated | required that the resin composition which comprises a temporary fixing material follows a fine unevenness | corrugation like a penetration electrode. In the manufacturing process of 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. I often don't know.

  Conventionally, fluidity is known as one of indexes for evaluating the performance of a resin composition. For example, by measuring the shear viscosity of the resin composition using a rheometer, the fluidity of the resin composition may be grasped and the quality of embedding may be judged. However, the large deformation of the film as described above and the ability to follow fine irregularities include events that cannot be explained only by 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. An object of the present disclosure is to provide a resin composition sorting method and a semiconductor device manufacturing method including the evaluation method.

  The present disclosure provides a method for evaluating the fluidity of a resin composition. This evaluation method includes a step of preparing a sample made of a resin composition, and measuring the shear modulus of the sample at temperature T by applying strain to the sample and measuring the shear modulus of the sample at temperature T. And a process of grasping changes. By grasping the temporal change of the shear modulus at the temperature T, the characteristics (deformability and followability to fine irregularities) of the resin composition can be more accurately evaluated. This evaluation method is useful, for example, for determining 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.

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) for stress relaxation of the Maxwell model based on the measurement result of the shear modulus of the sample. A step of reading the time (stress relaxation time τ) to become may be further included.
G (t) = G ₀ × e ^{(−t / τ)} (1)
[In the formula (1), G (t) represents the shear modulus at time t (seconds), G ₀ represents the initial shear modulus, t represents time (seconds), 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 for selecting a resin composition. In this selection method, the above-described fluidity evaluation method is performed under the condition that the temperature T is 120 ° C. and whether the evaluation target resin composition satisfies both of the following conditions 1 and 2 is determined. And a resin composition that satisfies both conditions 1 and 2 is determined to be good.
Condition 1: Stress relaxation time at 120 ° C. is 12 seconds or less.
Condition 2: The initial shear modulus at 120 ° C. is 35 kPa or less.

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

  The semiconductor device manufacturing method according to the present disclosure uses a 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 film characteristics (for example, deformability or followability to fine irregularities) that are difficult to explain only by shear viscosity. Moreover, according to this indication, the selection method of the resin composition containing the said evaluation method and the manufacturing method of a semiconductor device are provided.

FIG. 1 is a cross-sectional view schematically showing an example of a semiconductor device. 2 is a schematic cross-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. 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. 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 temporal changes in the shear modulus of the resin compositions according to Samples 1-14. FIG. 8 is a graph plotting the characteristics (horizontal axis: shear modulus [kPa], vertical axis: stress relaxation time τ (seconds)) of the resin compositions according to Samples 1-14.

  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 made of the resin composition, a strain applied to the sample, and a sample slip at temperature T. And measuring a change in shear modulus of the sample at temperature T by measuring the elastic modulus.

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) when G (t) / G ₀ = 0.3679 is obtained using the following formula (1) of stress relaxation of the Maxwell model. You may read. The initial shear modulus (G ₀ ) of the sample can be obtained based on the measurement result of the shear modulus of the sample.
G (t) = G ₀ × e ^{(−t / τ)} (1)
[In the formula (1), G (t) represents the shear modulus at time t (seconds), G ₀ represents the initial shear modulus, t represents time (seconds), and τ represents the stress relaxation time ( Seconds). ]

  The measurement of the shear modulus at the temperature T is preferably performed, for example, for at least 10 seconds, and the measurement time may be 30 to 1800 seconds or 60 to 600 seconds. The temperature T is preferably a specific temperature in the range of −50 to 400 ° C. from the viewpoint of performing stable measurement, and may be set according to the type and application of the resin composition to be evaluated. For example, when the kind of the resin composition is a thermosetting resin composition and the use 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. 50-200 degreeC or 80-150 degreeC may be sufficient.

  The amount of strain applied to the sample is preferably in the range of 0.1 to 30% from the viewpoint of performing 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 application is a die bonding film or a temporary fixing material used for manufacturing a semiconductor device, for example, the amount of distortion is 0.5 to 25. % And may be 1-20% or 2-15%.

  The sample is preferably formed in a film shape. 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 the use is a die bonding film in which a semiconductor chip (for example, a controller chip) is embedded in manufacturing 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 a film is too thin and it is difficult to measure the shear modulus, a sample with an increased thickness may be prepared by overlapping a plurality of sheets.

  According to the evaluation method according to the present embodiment, the characteristics of the resin composition can be more accurately evaluated by grasping the temporal change in the shear modulus at the temperature T. This evaluation method is useful, for example, for determining whether or not the embedding property of the resin composition constituting the die bonding film used in the manufacturing process of the semiconductor device is good.

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

  Regarding Condition 1, the stress relaxation time at 120 ° C. of 12 seconds or less means that the shear modulus decreases and fluidity increases in a sufficiently short time after heat is applied to the resin composition. . This contributes to shortening the time required for manufacturing 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 Condition 2, an initial shear modulus of 35 kPa or less at 120 ° C. means that the shear modulus is somewhat low 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 embodiment, the case where the shear modulus is measured under the condition that the temperature T is 120 ° C. is exemplified. However, the temperature T depends on the temperature condition in which the resin composition is used in the manufacturing process of the semiconductor device. May be set, for example, it may be 80 ° C. or 100 ° C., or 140 ° C.

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

  In the semiconductor device 100 shown in FIG. 1, a first semiconductor element Wa in the first stage is connected to a substrate 10 via a first wire 11 by wire bonding. Further, the second semiconductor element Wb and the first wire 11 are subjected to a process in which the second semiconductor element Wb is pressure-bonded onto the first semiconductor element Wa via a film adhesive (resin composition). Is a semiconductor device formed by being 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 with the sealing material 40. In this embodiment, the film adhesive 20P (refer FIG. 3) which consists of a thermosetting resin composition is an object which evaluates fluidity | liquidity. The film adhesive 20P becomes a cured product 20 by heat treatment.

  The substrate 10 has circuit patterns 10a and 10b on the 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 that the first semiconductor element Wa and a part of the circuit pattern 10b are covered. 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 a step 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 there is no void at the interface between the substrate 10 and the first semiconductor element Wa disposed on the surface thereof and the cured product 20.

  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 in which the first semiconductor element Wa is electrically connected to the substrate 10 through the first wire 11, and the second semiconductor element Wb. A step of preparing an adhesive-attached semiconductor element 30 having a film-like adhesive 20P affixed on one side thereof, a die bonding step of adhering the adhesive-attached semiconductor element 30 to the substrate 10, and a second semiconductor element Wb And a second wire bonding step of electrically connecting to the substrate 10 via the two wires 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 on the substrate 10 and the first pattern are connected to each other via the first wire 11. The semiconductor element Wa is electrically bonded and connected (first wire bonding step).

  As shown in FIG. 3, a second semiconductor element Wb and a semiconductor element 30 with an adhesive with a film adhesive 20P on one surface thereof are separately prepared (step of preparing a semiconductor element with an 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 surface of a semiconductor wafer, and passing through a dicing step and a pick-up step. Also good.

  Next, as illustrated in FIGS. 4 and 5, the adhesive-attached semiconductor element 30 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 20 </ b> P ( Die bonding process). In the die bonding step, the film adhesive 20P is preferably pressure-bonded for 0.5 to 3.0 seconds under conditions of 80 to 180 ° C. and 0.01 to 0.50 MPa. By pressing and heating the film-like adhesive 20P under the conditions of 60 to 175 ° C. and 0.3 to 0.7 MPa for 5 minutes or more, the film-like 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). Thereafter, the circuit pattern 10 b, the second wire 12, and the second semiconductor element Wb are sealed with a 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. However, a wire embedded type semiconductor in which only at least a part of the first wire 11 is embedded. It may be a device.

Moreover, in the said embodiment, although the semiconductor device using the embedding material (die-bonding film) which is one of the evaluation objects of fluidity and its manufacturing method were demonstrated, this indication is a temporary fixing material (resin film for temporary fixing). ) May be evaluated. And you may manufacture a semiconductor device using the temporary fixing material determined to be good by the selection method of this indication. Patent Document 2 describes in detail the specific configuration and method of use of the temporary fixing material. The manufacturing method of the semiconductor device using the temporarily fixing resin film includes the following steps, for example.
(A) A step of temporarily fixing a semiconductor wafer having a surface on which a circuit is formed and a support through a temporarily fixing resin film.
(B) The process of processing the semiconductor wafer temporarily fixed to the support body.
(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 individual pieces.
(E) A step of mounting a semiconductor element on a wiring board or the like.
In the step (a), the surface on which the circuit is formed (the surface having irregularities) is temporarily fixed so as to be in contact with the temporarily fixing resin film. When the temporarily fixing resin film is made of a thermosetting resin composition, a step of thermosetting the temporarily 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 laminate]
A total of 14 types of thermosetting resin compositions for die bonding or temporary fixing materials (subjects of fluidity evaluation) were prepared. Each resin composition was applied on a release treatment surface of a polyethylene terephthalate film (PET film, manufactured by Teijin DuPont Films, Inc., A31, thickness 38 μm), and then heat-dried at 90 ° C. for 5 minutes and 130 ° C. for 5 minutes. . Thereby, a resin layer (thickness: 30 μm) was formed on the PET film. A total of 14 types of laminates (PET film / resin composition / PET film) were prepared by further laminating another PET film as a protective film on the resin layer.

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

[Sample preparation]
As will be described later, a dynamic viscoelastic device ARES (manufactured by TA Instruments Inc.) was used for measurement of shear modulus and stress relaxation time. Since the measurement cannot be performed with the resin layer thickness of 30 μm, a sample (thickness 180 μm, 10 mm square) was obtained by punching after a 30 μm thick resin layer was roll laminated at 80 ° C. .

[Measurement of shear modulus]
A circular aluminum plate jig having a diameter of 8 mm was set in a dynamic viscoelastic device ARES (manufactured by TA Instruments), and a sample was set here. Thereafter, the sample was held at 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 modulus, the shear modulus immediately after applying the strain was defined as the initial shear modulus (G ₀ ). Tables 1 and 2 show the results of a total of 14 types of samples.

[Calculation of stress relaxation time (τ)]
From the measurement result of the shear modulus and the above equation (1), the stress relaxation time (τ) at which G (t) / G ₀ = 0.3679 was obtained. Tables 1 and 2 show the results of a total of 14 types of samples. FIG. 7 is a graph showing temporal changes in the shear modulus of the resin compositions according to Samples 1-14.

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

  A silicon mirror wafer (thickness: 725 μm) was placed on the stage of a vacuum laminator (LM-50X50-S, manufactured by NPC Corporation) so that the surface on which the grooves were formed was the upper surface. On top of that, a semiconductor chip with an adhesive was placed so that the side with the adhesive was on the bottom. Under the condition of 15 mbar, heating and pressing were performed for 2 minutes at a temperature of 120 ° C. and a pressure of 0.1 MPa, and vacuum lamination was performed.

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

As shown in Table 1, the resin compositions according to Samples 1 to 6 have 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 It was excellent in step embedding. On the other hand, as shown in Table 2, the resin composition (samples 7, 12, and 13) that does not satisfy both the conditions 1 and 2 has insufficient step embedding, and the conditions 1 and 2 The resin composition that does not satisfy one (Samples 8-11 and 14) also had insufficient step embedding. FIG. 8 is a graph in which the characteristics of the resin compositions according to Samples 1 to 14 (horizontal axis: initial shear modulus [kPa], vertical axis: stress relaxation time (seconds)) 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, 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 are provided.

DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 10a, 10b ... Circuit pattern, 11 ... 1st wire, 12 ... 2nd wire, 15 ... Adhesive, 20 ... Hardened | cured material of film adhesive, 20P ... Film adhesive (resin composition ), 30 ... Semiconductor element with adhesive, 40 ... Sealing material, 100 ... Semiconductor device, Wa ... First semiconductor element, Wb ... Second semiconductor element

Claims (11)

A method for evaluating the fluidity of a resin composition,
Preparing a sample comprising the resin composition;
Grasping the temporal change of the shear modulus of the sample at the temperature T by applying strain to the sample and measuring the shear modulus of the sample at the temperature T;
A fluidity evaluation method including Based on the measurement result of the shear modulus of the sample, a step of reading a time t that is G (t) / G ₀ = 0.3679, which is derived using the following formula (1) of stress relaxation of the Maxwell model The fluidity evaluation method according to claim 1, comprising:
G (t) = G ₀ × e ^{(−t / τ)} (1)
[In the formula (1), G (t) represents the shear modulus at time t (seconds), G ₀ represents the initial shear modulus, t represents time (seconds), 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 modulus based on a measurement result of a shear modulus of the sample.   The fluidity evaluation method according to any one of claims 1 to 3, wherein the shear 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 a range of -50 to 400 ° C.   The fluidity evaluation method according to any one of claims 1 to 5, wherein an amount of strain applied to the sample is 1 to 30%.   The fluidity evaluation method according to any one of claims 1 to 6, 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 an embedding material. Implementing the fluidity evaluation method according to any one of claims 1 to 9 under a condition in which the temperature T is 120 ° C;
A step of determining whether or not 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 of the conditions 1 and 2 is determined to be good.
Condition 1: Stress relaxation time at 120 ° C. is 12 seconds or less.
Condition 2: The initial shear 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 selection method according to claim 10 is used as an embedding material or a temporary fixing material.