TWI645533B - Apparatus and method for laser marking - Google Patents

Abstract

The present invention provides a method of forming a mark pattern on a sealing material for packaging a semiconductor element. The method includes illuminating a surface of a sealing material with a laser beam that causes a semiconductor element encapsulated by a sealing material to reduce a range of wafer breakage. The wavelength range of the laser beam is determined according to the transmittance spectrum of the filler included in the sealing material.

Description

Laser marking device and method

The present invention discloses a laser processing apparatus and method, and discloses a laser processing apparatus and method for improving the quality of laser processing by adjusting the shape of a laser pulse wave irradiated to a workpiece.

In general, the semiconductor package is configured by attaching a semiconductor wafer to a lead frame or the like, connecting the semiconductor wafer and the lead frame with a wire, and sealing the semiconductor wafer, the lead frame, and the like with a sealing material for a semiconductor package.

The sealing material for semiconductor encapsulation protects the semiconductor element from external impact, vibration, moisture, radiation, and the like. Before the 1960s, a metal or ceramic material was used as a sealing material for semiconductor encapsulation, but since the late 1960s, an epoxy molding compound (hereinafter referred to as EMC) which is easy to form and economical has been used.

After the sealing process of encapsulating the semiconductor element with the sealing material, various characters or patterns such as a manufacturing company, a product name, a manufacturing date, and a trademark are marked on the surface of the sealing material. Marking with ink or laser, mainly considering the convenience, speed and economy of the marking process Wait for the laser marker.

As the size of the semiconductor package is gradually smaller, the thickness of the sealing material for semiconductor package is gradually thinner. Further, since the thickness of the sealing material for a semiconductor package is reduced, a laser beam is transmitted through the sealing material and transmitted to the semiconductor element. Therefore, there is a problem that in the marking process of the surface of the sealing material, the semiconductor element inside the sealing material is damaged to cause defective products.

When the marking process is performed on the semiconductor package sealing material by using the laser beam, the semiconductor element is prevented from being damaged.

In one aspect, a laser marking method is provided, which is a method for forming a marking pattern on a sealing material for a semiconductor element package by using a laser beam, the laser marking method comprising the steps of: irradiating the surface of the sealing material without a step of forming a laser beam of a wavelength that breaks the semiconductor element encapsulated by the sealing material; and a step of forming the marking pattern on the sealing material while moving the irradiation region of the laser beam; and according to the sealing material The wavelength of the above-described laser beam is determined by the transmittance spectrum of the filler included.

The above-mentioned sealing material for a semiconductor element package may include an epoxy molding compound (EMC).

The above filler may include a cerium oxide (Silica) material.

The wavelength of the above-mentioned laser beam can be determined within a wavelength range in which the transmittance of the yttrium oxide material is small.

The above laser beam may have a wavelength of approximately 2.7 μm to 2.8 μm.

In another aspect, a laser marking device is provided that forms a marking pattern on a sealing material for a semiconductor component package using a laser beam, the laser marking device comprising: a light source that does not cause the sealing material to be encapsulated a laser beam having a wavelength at which the semiconductor element is broken; and a scanner that irradiates a surface of the sealing material with a laser beam emitted from the light source; and determining the thunder according to a transmittance spectrum of a filler included in the sealing material The wavelength of the beam.

The above-mentioned sealing material for a semiconductor element package may include an epoxy molding compound (EMC).

The above filler may include a cerium oxide (Silica) material.

The wavelength of the above-mentioned laser beam can be determined within a wavelength range in which the transmittance of the yttrium oxide material is small.

The above laser beam may have a wavelength of approximately 2.7 μm to 2.8 μm.

According to an exemplary embodiment, the semiconductor component packaged in the sealing material can be prevented from being damaged during the marking process using the laser beam.

10‧‧‧Semiconductor package

12‧‧‧ Sealing material

14‧‧‧Semiconductor components

15‧‧‧ mark pattern

20‧‧‧Filling agent

20a‧‧‧First filler

20b‧‧‧Second filler

50‧‧‧Focus optical system

110‧‧‧Light source

111‧‧‧Fiber

112‧‧‧beam collimator

114‧‧‧ Beam diameter amplifier

120‧‧‧Scanner

130‧‧‧ aperture

140‧‧‧ Concentrating lens

A1, A2‧‧‧ area

H1‧‧‧ distance

I-I'‧‧‧ line

L1, L2‧‧‧ laser beam

L3‧‧‧scatter beam

S1‧‧‧ area

S110, S120‧‧‧ steps

FIG. 1 is a perspective view exemplarily showing a state of a semiconductor package.

Fig. 2 is a cross-sectional view showing a cross section of the semiconductor package shown in Fig. 1 taken along line I'I'.

Fig. 3 is a view showing that a marking process is performed on a surface of a sealing material using a laser beam.

4 is a view exemplarily showing a mark product formed by the marking process shown in FIG.

Fig. 5 is a cross-sectional view showing a state in which a laser beam incident on a sealing material is scattered by EMC.

Fig. 6 is a cross-sectional view showing another example of a case where a laser beam incident on a sealing material is scattered by EMC.

7 is a cross-sectional view showing an example in which a laser beam incident on a sealing material reaches a semiconductor element through a filler.

Fig. 8 is an enlarged view of the S1 area shown in Fig. 7;

FIG. 9 is a view exemplarily showing a traveling path of a laser beam when the dimensional ratios of the first filler and the second filler are different.

Figure 10 is a flow chart showing a laser marking method of an exemplary embodiment.

Fig. 11 is a graph showing the transmittance of each wavelength of light in yttrium oxide.

Fig. 12 is a view schematically showing a laser marking device of an exemplary embodiment.

Figure 13 is an energy level diagram of Erbium doped glass fiber (hereinafter referred to as EDF).

In the following drawings, the same reference numerals denote the same constituent elements, and in the drawings, the dimensions of the respective constituent elements may be exaggerated for clarity and convenience of explanation. another In one aspect, the embodiments described below are merely examples, and various modifications may be implemented in accordance with the embodiments.

The first and second terms can be used to describe various constituent elements, but the constituent elements should not be limited by the terms. The term is used only for the purpose of distinguishing one component from other components.

As long as the other meanings are not explicitly indicated in the text, the singular expression includes the plural expression. In addition, when a part is "included" as a certain component, unless otherwise indicated, it means that it may include other components, and does not mean that other components are excluded.

Further, terms such as "parts" and "modules" described in the specification refer to units that process at least one function or operation.

FIG. 1 is a perspective view exemplarily showing a state of the semiconductor package 10.

Referring to FIG. 1, the semiconductor element 14 can be sealed by a sealing material 12. The semiconductor element 14 can be an electronic device using a semiconductor such as a semiconductor wafer, an integrated circuit (IC), or a large scale IC (LSI), and is not limited to the above example. In FIG. 1, the semiconductor element 14 is simply shown in the inside of the sealing material 12, but an additional component can be further incorporated in the inside of the sealing material 12. For example, a wire, a lead frame, a solder ball, or the like for connecting the semiconductor element 14 to an external circuit may be further incorporated inside the sealing material 12.

The sealing material 12 may illustratively include an Epoxy Molding Compound (hereinafter referred to as EMC). The sealing material 12 can function to protect the semiconductor element 14 from the external environment such as impact, radiation, moisture, and the like. Further, the sealing member 12 can provide surface mounting convenience when the semiconductor package 10 is mounted to other devices. In the picture In the first embodiment, the shape of the semiconductor package 10 is a regular hexahedron. However, the embodiment is not limited thereto, and the shape of the semiconductor package 10 may be changed depending on the shape of the other device.

FIG. 2 is a cross-sectional view showing a cross section of the semiconductor package 10 shown in FIG. 1 taken along the line II'.

Referring to FIG. 2, a plurality of fillers (fillers 20) may be included between the EMC of the sealing material 12. The filler may be exemplarily in the shape of a spherical particle, and its size may also be different. The filler 20 can support the sealing material 12 to maintain the sealing material 12 in a fixed shape. The filler 20 is exemplarily a particle of cerium oxide (Silica; SiO ₂ ). However, the material of the filler 20 is not limited thereto. For example, the filler 20 may also be realized by particles of other materials that are added to the EMC to maintain the shape of the sealing material 12.

FIG. 3 is a view showing that the marking process is performed on the surface of the sealing material 12 by the laser beam L1. 4 is a view exemplarily showing a mark product formed by the marking process shown in FIG.

Referring to Fig. 3, the surface of the sealing material 12 can be irradiated with a laser beam L1. The laser beam L1 can be focused to the surface of the sealing material 12 by the focusing optical system 50. However, the above is merely an example, and the laser beam L1 may be irradiated to the surface of the sealing material 12 without passing through the focusing optical system 50. As described above, if the sealing material 12 includes EMC, the energy of the laser beam L1 can be absorbed by the carbon atoms included in the epoxy resin. If the surface of the sealing material 12 absorbs the energy of the laser beam L1, a part of the surface of the sealing material 12 can be decomposed by the laser beam L1 as shown in FIG. Further, when the position of the irradiation laser beam L1 is moved in accordance with the desired mark shape, the marking pattern 15 can be formed on the surface of the sealing material 12 as shown in FIG.

A part of the laser beam L1 incident on the surface of the sealing material 12 can be transmitted to the dense The inside of the sealing material 12. In addition, a part of the laser beam L1 transmitted to the inside of the sealing material 12 can reach the semiconductor element 14 located inside the sealing material 12. If the laser beam L1 is transmitted to the semiconductor element 14, damage to the semiconductor element 14 is caused, and thus the yield of the manufacturing process of the semiconductor package 10 is lowered. However, the laser beam that does not reach the semiconductor element 14 causes damage to the semiconductor element 14. A portion of the laser beam is scattered by the EMC of the sealing material 12, or even if it is absorbed to reach the semiconductor element 14, the energy density of the laser beam is also small.

FIG. 5 is a cross-sectional view showing a state in which the laser beam L1 incident on the sealing material 12 is scattered by EMC.

Referring to FIG. 5, a part of the laser beam L1 incident on the surface of the sealing material 12 may be transmitted to the inside of the sealing material 12. Among them, the transmitted laser beam L1 can be absorbed or scattered by EMC. The laser beam L2 scattered by EMC decreases the amount of energy per unit area as the scattering area becomes wider. Therefore, even if the laser beam L2 scattered by the EMC inside the sealing material 12 reaches the semiconductor element 14, the semiconductor element 14 is not greatly damaged.

FIG. 6 is a cross-sectional view showing another example of the case where the laser beam L1 incident on the sealing material 12 is scattered by EMC.

Referring to FIG. 6, a portion of the laser beam L1 incident on the sealing material 12 may reach the filler 20 included in the sealing material 12. In the case where the filler 20 is in the shape of a sphere, the filler 20 can perform the function of an optical element that focuses the incident laser beam. That is, the laser beam can be focused inside the filler 20 instead of being scattered. Among them, in the example shown in FIG. 6, the laser beam passing through the filler 20 will again meet EMC. Therefore, most of the laser beam is absorbed or scattered again on the EMC. The scattered beam L3 scattered by EMC decreases the amount of energy transfer per unit area as the scattering area becomes wider. Therefore, in the example shown in FIG. 6, the laser beam L1 transmitted to the inside of the sealing member 12 does not cause a large influence on the semiconductor element 14. damage.

FIG. 7 is a cross-sectional view showing an example in which the laser beam L1 incident on the sealing material 12 reaches the semiconductor element 14 by the filler 20.

Referring to FIG. 7, the laser beam L1 incident on the sealing material 12 may be incident on the filler 20 via EMC. In FIG. 7, a plurality of fillers 20 may be arranged in the S1 region along the traveling path of the laser beam L1. In this case, the filler 20 can function as an optical waveguide of the laser beam L1. That is, unlike in EMC, the laser beam L1 passing through the filler 20 is transmitted to the semiconductor element 14 without being scattered. Further, when the filler 20 has a spherical shape as shown in FIG. 7, the filler 20 can function together with the convex lens to focus the laser beam L1.

Fig. 8 is an enlarged view of the S1 area shown in Fig. 7;

Referring to FIG. 8, the laser beam L1 incident on the surface of the sealing material 12 may be incident on the filler 20. If the distance h1 between the surface of the sealing material 12 and the surface of the filler 20 is small, as shown in FIG. 8, the EMC portion covering the filler 20 in the marking process is peeled off and the surface of the filler 20 is exposed to the outside. Thus, the energy of the laser beam L1 can be incident on the filler 20 in a state of almost no loss. Further, when the EMC of the surface of the filler 20 is not completely peeled off as shown in FIG. 8, if the distance h1 between the surface of the sealing material 12 and the surface of the filler 20 is small, a considerable portion of the laser beam L1 is present. The ratio is not incident or otherwise incident on the filler 20 by EMC scattering or absorption.

When the first filler 20a and the second filler 20b are continuously arranged in the traveling path of the laser beam L1 as shown in FIG. 8, the laser beam L1 is transmitted to the surface of the semiconductor element 14 without being scattered. Further, when the first filler 20a and the second filler 20b are spherical, the laser beam L1 is focused inside the first filler 20a and the second filler 20b. The path through which the laser beam L1 travels may differ depending on the refractive index of the material of the filler 20. In Figure 8, An example in which the laser beam L1 forms a light collecting point inside the second filler 20b is shown. However, the position at which the laser beam L1 forms a condensed spot can be changed. For example, the laser beam L1 may also form a light collecting spot at the first filler 20a. Alternatively, the laser beam L1 may not form a light collecting spot during the transmission of the first filler 20a and the second filler 20b.

If the laser beam L1 transmits the first filler 20a and the second filler 20b, the surface of the semiconductor element 14 can be reached. In the semiconductor element 14, the area A2 reached by the laser beam L1 may have almost the same size as the area A1 of the surface on which the laser beam L1 is incident on the sealing material 12. Therefore, the energy per unit area of the laser beam L1 transmitted to the semiconductor element 14 is almost close to the energy transfer amount per unit area of the laser beam utilized in the laser mark. Then, the surface temperature of the semiconductor element 14 incident on the laser beam L1 rises above a critical value to cause damage to the semiconductor element 14.

FIG. 9 is a view exemplarily showing a travel path of the laser beam L1 when the dimensional ratios of the first filler 20a and the second filler 20b are different.

Referring to Fig. 9, a first filler 20a and a second filler 20b may be arranged side by side on the traveling path of the laser beam L1. Also, the size of the first filler 20a may be larger than that of the second filler 20b. If the size of the first filler 20a is large, the radius of curvature of the surface of the first filler 20a becomes relatively small and the angle at which the laser beam L1 is refracted becomes small. Therefore, the condensed spot of the laser beam L1 is formed in a manner relatively closer to the surface of the semiconductor element 14 than in the case of FIG. In addition, the incident area A2 of the laser beam L1 incident to the semiconductor element 14 may be smaller than the incident area A1 of the laser beam L1 incident to the sealing material 12. As the incident area A2 becomes smaller, the energy per unit area of the laser beam transmitted to the semiconductor element 14 becomes large, so that damage of the semiconductor element 14 is often caused.

As explained above, the laser beam L1 transmitting the filler 20 will be on the semiconductor element 14 The damage has the greatest impact. In order to prevent the above-described semiconductor element 14 from being damaged, the laser marking method of the exemplary embodiment can appropriately adjust the wavelength of the laser beam.

Figure 10 is a flow chart showing a laser marking method of an exemplary embodiment.

Referring to FIG. 10, the laser marking method of the exemplary embodiment may include the steps of: irradiating a laser beam of a wavelength capable of preventing breakage of the semiconductor element 14 to a surface of the sealing member 12; and moving the laser beam while moving the laser beam In the irradiation region, a step S120 of forming a marking pattern on the sealing member 12 is performed.

In step S110 of irradiating the laser beam, a laser beam of a wavelength that does not damage the semiconductor element 14 can be irradiated. When the laser beam irradiated to the sealing material 12 is transmitted to the semiconductor element 14 by the transmission filler 20, damage of the semiconductor element 14 is caused. Therefore, the wavelength of the laser beam can be determined according to the transmittance spectrum of the filler 20 included in the sealing material 12. That is, the wavelength of the laser beam can be determined as the wavelength at which the transmittance to the filler 20 is small. For example, in the case where the sealing material 12 includes EMC and a filler 20 of cerium oxide material included between EMC, the wavelength of the laser beam can be determined within a wavelength range in which the transmittance of cerium oxide is small.

Fig. 11 is a graph showing the transmittance of each wavelength of light in yttrium oxide.

In Fig. 11, the vertical axis represents the transmittance of light, and the horizontal axis represents the wavelength of light. Referring to Fig. 11, when the wavelength of light is approximately 2.7 μm to 2.8 μm, the transmittance of light to yttrium oxide is almost converged to zero. That is, a laser beam having a wavelength of approximately 2.7 μm to 2.8 μm is largely incapable of transmitting the filler 20 when it is incident on the filler 20 of cerium oxide material. Conversely, the carbon atoms of EMC can well absorb the laser beam of the above wavelengths of approximately 2.7 μm to 2.8 μm. Therefore, if the wavelength of the laser beam is set as described above, the marking process can be realized on the surface of the EMC. Also, the laser beam of the filler 20 incident between the EMCs may not transmit the filler 20. Thereby, the laser beam can be condensed by the filler 20 as shown in FIGS. 7 to 9 to prevent entry. The semiconductor element 14 is incident.

In the step S120 of forming the marking pattern, the marking pattern can be formed on the sealing material 12 while moving the irradiation position of the laser beam. In the step S120 of forming the mark pattern, the mark pattern shown in FIG. 4 may be formed without causing damage to the semiconductor element 14.

The filler 20 made of cerium oxide material has been described as an example. However, the embodiment is not limited to this. The material of the filler 20 can be varied so that the wavelength of the laser beam can also be varied. The wavelength of the laser beam can be determined within a wavelength range that is well absorbed by EMC and that has a low transmittance to the filler 20.

The laser marking method of the exemplary embodiment has been described above with reference to FIGS. 10 and 11. Hereinafter, a laser marking device for carrying out the above-described laser marking method will be described.

Fig. 12 is a view schematically showing a laser marking device of an exemplary embodiment.

Referring to FIG. 12, the laser marking device of the exemplary embodiment may include: a light source 110; and a scanner 120 that illuminates a laser beam emitted from the light source 110 to the surface of the sealing material 12. As described above, the wavelength of the laser beam emitted from the light source 110 can be determined as the wavelength at which the transmittance to the filler 20 is small. Further, the wavelength of the laser beam emitted from the light source 110 can be determined as a wavelength that is well absorbed by EMC.

In the case where the filler 20 includes a cerium oxide material, the wavelength of the laser beam emitted from the light source 110 may be approximately 2.7 μm to 2.8 μm. In order to emit a laser beam of the above wavelength range, the light source 110 may utilize Erbium doped glass fiber (EDF). For example, the light source 110 can include a resonator including erbium doped glass fibers, and a pumping light source that emits pumping light to the resonator. The pumping light source can emit pumping light having a wavelength of 980 nm or more to the resonator. The resonator can emit with erbium-doped glass fiber as a gain medium A laser beam having a wavelength of approximately 2.7 μm to 3.0 μm.

Figure 13 is an energy level diagram of Erbium doped glass fiber (hereinafter referred to as EDF).

Referring to Fig. 13, when the pump light of the 980 nm band is incident on the EDF, ground state absorption (hereinafter referred to as GSA) can be generated to excite the ground state in the excited state ( ⁴ I _11/2 ) ( ⁴ I _{15 /2} ) of the electrons. Further, it is possible to emit laser light of approximately 2.8 μm from the above-described excited state ( ⁴ I _11/2 ) to the ground state ( ⁴ I _13/2 ). That is, the light source 110 can emit a laser beam having a wavelength of approximately 2.7 μm to 3.0 μm with the EDF as a gain medium.

Referring again to Figure 12, the laser marking device can include an optical fiber 111 that transmits a laser beam emerging from the light source 110, and a beam collimator 112 that aligns the laser beam. Further, in the case where the beam size of the laser beam emitted from the beam collimator 112 is small, the beam diameter amplifying means 114 for amplifying the beam size of the laser beam may be included. The beam diameter amplifying device may include a plurality of lenses. The lens included in the beam diameter amplifier may include a material having a good transmittance of the wavelength of the laser beam emitted from the light source 110. For example, in the case where the light source 110 emits a laser beam having a wavelength of approximately 2.7 μm to 2.8 μm, the lens included in the beam diameter amplifier may include a material having a higher transmittance for the above wavelength range.

Scanner 120 can adjust the direction in which the laser beam is illuminated. Scanner 120 can include at least one mirror. The scanner 120 can adjust the position of the laser beam to the surface of the sealing material 12 by changing the angle and position of the mirror. The mirror included in the scanner 120 may include a material having a good reflectance of the wavelength of the laser beam emitted from the light source 110. For example, in the case where the light source 110 emits a laser beam having a wavelength of approximately 2.7 μm to 2.8 μm, the mirror included in the scanner 120 may include a material having a high reflectance for the above wavelength range.

Moreover, the laser marking device may further include an aperture 130 and a collecting lens 140. Light The circle 130 can adjust the diameter of the laser beam differently depending on the shape of the mark by changing the size of the area through which the laser beam can pass. Also, the condenser lens 140 can condense the laser beam to a region of the surface of the sealing material 12.

The laser marking method and apparatus of the exemplary embodiments have been described above. According to the embodiment described above, the marking process can be performed on the sealing material 12 of the semiconductor package 10 using the laser beam. Here, the wavelength of the laser beam can be adjusted in such a manner that the transmittance of the filler 20 included in the sealing material 12 by the laser beam is small. Thereby, the semiconductor element 14 packaged in the sealing material 12 can be prevented from being damaged during the marking process using the laser beam.

In the above description, a plurality of items are specifically described, but these matters are not intended to limit the scope of the invention, but should be construed as an example of a preferred embodiment. Therefore, the scope of the invention should not be limited by the illustrated embodiments, but should be defined by the technical idea recited in the claims.

Claims (4)

A laser marking method, which is a method for forming a marking pattern on a sealing material for a semiconductor element package by using a laser beam, the laser marking method comprising the steps of: irradiating a surface of the sealing material without causing a step of a laser beam of a wavelength at which the semiconductor element of the sealing material package is broken; and a step of forming the marking pattern on the sealing material while moving the irradiation area of the laser beam; and according to the sealing The wavelength of the laser beam is determined by a transmittance spectrum of a filler, wherein the sealing material comprises an epoxy molding compound, wherein the filler comprises a cerium oxide material, wherein a wavelength of the laser beam It is 2.7 μm to 2.8 μm. The laser marking method of claim 1, wherein the wavelength of the laser beam is determined within a wavelength range in which the transmittance of the yttria material is small. A laser marking device that forms a marking pattern on a sealing material for a semiconductor element package using a laser beam, the laser marking device comprising: a light source that does not break the semiconductor element encapsulated by the sealing material a laser beam of a wavelength; and a scanner that irradiates a surface of the sealing material with a laser beam emitted from the light source; and determines the lightning according to a transmittance spectrum of a filler included in the sealing material a wavelength of the beam, wherein the sealing material comprises an epoxy molding compound, wherein the filler comprises a cerium oxide material, Wherein the wavelength of the laser beam is from 2.7 μm to 2.8 μm. The laser marking device of claim 3, wherein the wavelength of the laser beam is determined within a wavelength range in which the transmittance of the yttria material is small.