JP2002025945A - Dicing method for semiconductor wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of defective cuts in dicing a semiconductor wafer on which adhesive is applied by improving the elastic modulus of the adhesive. SOLUTION: At the time of applying an adhesive 40 to one face side of a semiconductor wafer 11 and dicing a semiconductor wafer from an adhesive applied face side, the temperature of the adhesive is set to be not more than a glass transfer temperature Tg, the semiconductor wafer is diced. The high frequency vibration of not less than 105 Hz is given to the adhesive and the semiconductor wafer is diced. Thus, the wafer can be diced in an area where the elastic modulus of the adhesive is high and the adhesive is prevented from bending. The pressure of a dicing blade 60 can surely be transmitted to the adhesive and the occurrence of the cutting defects of the sensor chip 10 can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dicing a semiconductor wafer, and more particularly, to a method for dicing a semiconductor wafer, and dicing the semiconductor wafer from the side on which the adhesive is applied. , Pressure sensor)
The present invention relates to a method for dicing a semiconductor wafer for manufacturing a sensor chip.

[0002]

2. Description of the Related Art When a semiconductor dynamic quantity sensor such as an acceleration sensor or a pressure sensor is mounted, a sensor chip is often fixed to a housing made of resin, ceramic, or the like with an adhesive or the like. As this adhesive, a material having low elasticity and large elongation is used for the purpose of relaxing stress from a base such as a housing.

As a method of applying an adhesive to a sensor chip, it is difficult to apply an adhesive after cutting a semiconductor wafer into small sensor chips each having a size of several mm square. Thereafter, the semiconductor wafer is diced with a dicing blade to divide the semiconductor wafer into individual chips.

Further, since the silicon surface of the semiconductor wafer is a sensor element, dicing from the silicon surface requires surface protection, but dicing from the adhesive-coated surface does not require surface protection. For this reason, when dicing a semiconductor wafer for the purpose of reducing the number of steps, dicing is performed from the side where the adhesive is applied.

[0005]

FIG. 6 shows the relationship between the modulus of elasticity of the silicone adhesive and the temperature (frequency 1 Hz), and FIG. 7 shows the relationship between the modulus of elasticity of the silicone adhesive and the frequency (temperature 25 ° C.). As shown in FIGS. 6 and 7, the elastic modulus of the adhesive is affected by temperature and frequency.

Normally, dicing of a semiconductor wafer is performed at room temperature and in an environment that receives low-frequency vibration (about 1 Hz). In such an environment, as shown in FIGS. 6 and 7, an area where the elastic modulus of the adhesive is low is used. For this reason, at the time of dicing, the pressure of the dicing blade causes the adhesive to bend like a cushion, making it difficult to transmit pressure to the semiconductor wafer. For this reason, there is a problem that a defective cutting of the sensor chip is likely to occur.

SUMMARY OF THE INVENTION In view of the above problems, the present invention provides a method for dicing a semiconductor wafer coated with an adhesive.
An object of the present invention is to improve the modulus of elasticity of an adhesive to prevent cutting failure.

[0008]

To achieve the above object, according to the first aspect of the present invention, a semiconductor wafer (11) is provided.
Is a method in which an adhesive (40) is applied to one side of the semiconductor wafer and the semiconductor wafer is diced from the side where the adhesive is applied. The dicing of the semiconductor wafer is performed by setting the temperature of the adhesive to a glass transition temperature (Tg) or lower. It is characterized by:

As shown in FIG. 6, the elastic modulus of the adhesive (40) depends on the temperature. At a temperature lower than the glass transition temperature (Tg), the elastic modulus becomes extremely high. Therefore, claim 1
According to the described invention, dicing of the semiconductor wafer (11) can be performed in a state where the elasticity of the adhesive (40) is high, so that the adhesive does not bend during dicing.
Therefore, the pressure of the dicing blade (60) can be reliably transmitted to the adhesive, and the occurrence of defective cutting of the sensor chip (10) can be prevented.

Further, the invention according to claim 2 is characterized in that a semiconductor wafer is diced by applying a high frequency vibration of 10 ⁵ Hz or more to the adhesive.

As shown in FIG. 7, the elastic modulus of the adhesive (40) depends on the vibration frequency. The higher the vibration frequency, the higher the elastic modulus. If the vibration frequency is 10 ⁵ Hz or more, the elasticity is sufficiently high. High elastic modulus is obtained. Therefore, according to the second aspect of the present invention, the dicing of the semiconductor wafer (11) can be performed in a state where the elasticity of the adhesive is high. )
Can be prevented from occurring.

According to the third aspect of the present invention, the dicing of the semiconductor wafer can be performed by applying a high frequency vibration of 10 ⁵ Hz or more to the adhesive at the same time as lowering the temperature of the adhesive to the glass transition temperature (Tg) or less. Good.

The reference numerals in parentheses of the above means indicate the correspondence with specific means described in the embodiments described later.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of the present invention will be described below with reference to FIGS. The first embodiment is applied to an acceleration sensor (dynamic quantity sensor).

FIG. 1 shows the overall configuration of the acceleration sensor 100. As shown in FIG. 1, the acceleration sensor of the first embodiment includes a sensor chip 10 made of silicon, a circuit chip 20, and a package 30 made of ceramic.

The sensor chip 10 has comb teeth (not shown). The comb teeth change the capacitance between the comb teeth by acceleration, and are configured to detect the acceleration based on the change in the capacitance. A wiring pattern (not shown) is formed on the circuit chip 20. The sensor chip 10, the circuit chip 20, and the package 30 each have electrodes (pad portions) not shown.
Are formed and are electrically connected by wire bonding using the wires 50 and 51.

The acceleration sensor 100 according to the first embodiment includes:
As a method of reducing the mounting area for cost reduction, a stack structure in which chips 10 and 20 are stacked as shown in FIG. 1 is adopted. In adopting such a stack structure, the bonding between the sensor chip 10 and the circuit chip 20 is prevented in order to prevent the adhesive from bleeding out of a low molecular weight (bleed) on a pad portion (not shown) and deteriorating the bonding property. Is the adhesive film 4 of the brie dress
0 is used. The circuit chip 20 is fixed to the package 30 by an adhesive 41.

In the first embodiment, a silicon-based adhesive is used as the adhesive film 40 and the adhesive 41.

Next, a method of manufacturing the sensor chip 10 will be described with reference to FIGS. FIG. 2 shows the sensor chip 1
0 shows a manufacturing process, FIG. 3 shows a cross-sectional state of the dicing process of the semiconductor wafer 11, and FIG. 4 shows a stage 61 used in the dicing process of the semiconductor wafer 11.

First, a semiconductor wafer 11 is prepared, and an adhesive film 40 is applied to one surface of the semiconductor wafer 11 (FIG. 2A). Next, the adhesive film 40 applied to the semiconductor wafer 11 is temporarily cured (FIG. 2B). Next, using a dicing blade 60, the semiconductor wafer 11 is diced from the surface to which the adhesive film 40 has been applied, and cut into individual sensor chips 10 (FIGS. 2C and 3).

At this time, the reason why the adhesive film 40 is applied to the semiconductor wafer 11 in advance and then diced is that it is difficult to apply the adhesive film 40 after cutting into individual sensor chips 10 (several mm square). . Dicing the semiconductor wafer 11 from the side on which the adhesive film is applied is because surface protection is not required as compared with dicing from a silicon surface, which leads to a reduction in man-hours.

The dicing process for the semiconductor wafer 11 is performed by fixing the semiconductor wafer 11 on a stage 61 made of metal such as stainless steel as shown in FIG. Stage 61
Has a cooling means for cooling the adhesive film 40 to a glass transition temperature Tg or lower. A fluid passage 61a is formed inside the stage 61, and a fluid such as liquid nitrogen passes through the fluid passage 61a to constitute a cooling unit. When dicing the semiconductor wafer 11, by circulating a low-temperature fluid such as liquid nitrogen through the fluid passage 61a, the adhesive film 40 can be cooled to a glass transition temperature Tg or lower.

FIG. 6 shows the elastic modulus (P
The relationship between a) and temperature (° C.) is shown. The vibration frequency at this time is 1 Hz. As shown in FIG. 6, the elastic modulus of the adhesive film (adhesive) 40 depends on the temperature. At a temperature lower than the glass transition temperature Tg, the elastic modulus becomes extremely high. Therefore, according to the present embodiment, the semiconductor wafer 11 can be diced in a state where the adhesive film 40 has a high elastic modulus.
There is no deflection. Therefore, the dicing blade 60
Of the sensor chip 10 can be reliably transmitted to the adhesive film 40, and it is possible to prevent the occurrence of cutting failure of the sensor chip 10.

The sensor chip 10 manufactured as described above
Is bonded to the circuit chip 20, the circuit chip 20 is bonded to the package 30, and further, wire bonding or the like is performed to manufacture the acceleration sensor 100 shown in FIG.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. The second embodiment differs from the first embodiment in the stage used when dicing a semiconductor wafer. The same parts as those in the first embodiment are denoted by the same reference numerals, and description thereof is omitted.

As shown in FIG. 5, the stage 62 of the second embodiment is provided with a piezoelectric element (vibrator) 62a having electrodes (not shown). By applying a voltage to the piezoelectric element 62a, a high frequency vibration of 10 ⁵ Hz or more can be generated in the stage 62. As the piezoelectric element 62a, for example, piezoelectric ceramics can be used.

FIG. 7 shows the elastic modulus (P
2 shows the relationship between a) and the vibration frequency (Hz). The temperature at this time is 25 ° C. As shown in FIG. 7, the elastic modulus of the adhesive film (adhesive) 40 depends on the vibration frequency. The higher the vibration frequency, the smaller the amount of displacement and the higher the elastic modulus. As shown in FIG. 7, a sufficiently high elastic modulus can be obtained at a vibration frequency of 10 ⁵ Hz or more.

Therefore, according to the second embodiment, the semiconductor wafer 11 can be diced while the elasticity of the adhesive film 40 is high, as in the first embodiment. 40 does not flex. Therefore, the pressure of the dicing blade 60 can be reliably transmitted to the adhesive film 40, and it is possible to prevent the occurrence of a cutting failure of the sensor chip 10.

(Other Embodiments) The adhesive film 40 used in the first embodiment is set to have a glass transition temperature Tg or lower, and the adhesive film 4 used in the second embodiment is used.
The semiconductor wafer 11 may be diced by simultaneously applying a high-frequency vibration of 10 ⁵ Hz or more to 0.

In the first embodiment, the stage 6
Although liquid nitrogen was circulated inside the stage 61 as a cooling means for cooling 1, the present invention is not limited to this, and it is sufficient that the adhesive film (adhesive) 40 can be cooled to a glass transition temperature Tg or lower. it can.

In each of the above embodiments, the present invention relates to the sensor chip 1 in the acceleration sensor 100 having a stack structure.
However, the present invention is not limited to this, and the present invention is applicable as long as a sensor chip is obtained by dicing a semiconductor wafer on which an adhesive has been applied from the adhesive surface side. It may be fixed to the package with an agent. Further, the present invention is not limited to the acceleration sensor, and can be applied to a pressure sensor having a piezoresistor (strain gauge) having a similar configuration.

In each of the above embodiments, a silicon-based adhesive was used as the adhesive film (adhesive). However, the present invention is not limited to this. Epoxy, polyimide, acrylic, urethane, rubber, and liquid crystal polymer-based adhesives are used. And the like can be used. These various adhesives also have the same temperature-dependent characteristics and frequency-dependent characteristics as the silicon-based adhesives shown in FIGS. 6 and 7, and even when these various adhesives are used, the same as in the above-described embodiments. The effect of can be obtained.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an acceleration sensor according to a first embodiment of the present invention.

FIG. 2 is a process chart showing a method for manufacturing the sensor chip of the first embodiment.

FIG. 3 is a cross-sectional view illustrating a dicing step of the semiconductor wafer of the first embodiment.

FIG. 4 is a perspective view showing a stage used for dicing the semiconductor wafer of the first embodiment.

FIG. 5 is a perspective view showing a stage used for dicing a semiconductor wafer according to a second embodiment.

FIG. 6 is a graph showing the relationship between the modulus of elasticity of silicone adhesive and temperature.

FIG. 7 is a graph showing the relationship between elastic modulus and frequency of a silicon-based adhesive.

[Explanation of symbols]

10: sensor chip, 20: circuit chip, 30: package, 40: adhesive film (adhesive).

Claims (3)

[Claims] 1. A method of applying an adhesive (40) to one surface of a semiconductor wafer (11) and dicing the semiconductor wafer from an adhesive applied surface, wherein the temperature of the adhesive is set to a glass transition temperature ( Tg) A dicing method for a semiconductor wafer, wherein the dicing of the semiconductor wafer is performed as follows. 2. A method of applying an adhesive (40) to one surface of a semiconductor wafer (11) and dicing the semiconductor wafer from an adhesive-applied surface, wherein the adhesive has a high frequency of 10 ⁵ Hz or more. A dicing method for a semiconductor wafer, wherein the semiconductor wafer is diced by applying vibration. 3. A method of applying an adhesive (40) to one surface side of a semiconductor wafer (11) and dicing the semiconductor wafer from an adhesive application surface side, wherein the temperature of the adhesive is set to a glass transition temperature ( Tg) or less, and dicing the semiconductor wafer by applying high-frequency vibration of 10 ⁵ Hz or more to the adhesive.