JP3459154B2 - Semiconductor device and laser scribing method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor device including a laminated body of a metal layer and a semiconductor wafer and a scribing method thereof.

[0002]

2. Description of the Related Art A large number of semiconductor devices formed on a semiconductor wafer are divided into individual semiconductor chips before packaging. This process is called scribing or dicing. When using a laser,
Scribing is used. In the following description, both scribing and dicing are used.

In the dicing process, a dicing cut method using a diamond wheel is used. The dicing cut method is a method in which a thin disk having diamond powder embedded therein is rotated at high speed to cut a semiconductor wafer, and there are the following two methods. (1) Using a diamond wheel that rotates at a high speed, a cutting groove having a depth of ½ or more of the thickness of the semiconductor wafer is formed in the dicing portion, and the semiconductor wafer is divided into individual semiconductor chips along the cutting groove ( How to brake). (2) A method in which a semiconductor wafer is attached to an expandable sheet having adhesiveness on one side, and a dicing portion is cut to a position where the expandable sheet is slightly cut using a diamond wheel that rotates at high speed to completely cut the dicing portion.

When the semiconductor device is diced by the dicing cut method according to the above methods (1) and (2),
If the majority of the dicing portion is made of a semiconductor wafer, dicing can be performed well. Because semiconductors are hard and brittle (hard and brittle),
This is because it is suitable for cutting and separating with a diamond wheel that rotates at high speed. However, good dicing can be performed when the dicing portion is made of only metal or when the dicing portion is made of a laminated body of a semiconductor wafer and a metal layer and the thickness of the metal layer is equal to or thicker than the thickness of the semiconductor wafer. Can not. Because metal is softer and more sticky than semiconductors, burrs are likely to occur during cutting. As described above, it is difficult to dice the semiconductor device having the dicing portion including the thick metal layer by the dicing cut method.

Further, in a high-frequency device or the like, the thickness of the semiconductor wafer is very thin, about 30 μm. As the semiconductor wafer becomes thinner as described above, it is more likely to be broken, so that the cutting speed (the relative moving speed between the diamond wheel and the semiconductor device) cannot be increased, which causes a problem that the throughput cannot be increased.

Due to the above-mentioned problems, it is difficult to apply the dicing cut method to a GaAs high frequency device or the like which is composed of a laminated body of a thick metal layer for heat dissipation and a semiconductor wafer.

[0007]

As a solution to the above problems, the present inventors have previously proposed a scribing method by a laser fusing method (Japanese Patent Application No. 7-659).
94). FIG. 6 is a diagram showing each step of the scribing method by the laser fusing method according to this earlier application,
In the figure, reference numeral 52 denotes a metal layer which forms a heat sink (heat radiator), and is made of a material such as gold (Au). 54 is GaA
a semiconductor wafer made of s or the like, 56 a laminated body made of a metal layer 52 and a semiconductor wafer 54, 57 a scribing section, 58 a semiconductor wafer removing section obtained by removing the semiconductor wafer 54 of the scribing section 57 by etching, 60
Is a groove formed by etching the metal layer 52 of the scribing part 57, and 62 is an expand sheet to which the laminated body 56 is attached, and is made of a material that transmits a laser beam. 64 is a laser beam emitted from a YAG (yttrium-aluminum-garnet) laser or the like, 66
Is a molten and solidified portion generated in the metal layer 52 irradiated with the laser beam 64, and 68 is a scribing hole.

Next, the operation will be described. First, a metal layer 52 which is a heat sink made of Au or the like is formed on the back surface of a semiconductor wafer 54 made of GaAs or the like having a circuit pattern formed on the front surface. As a result, a laminated body 56 including the metal layer 52 and the semiconductor wafer 54 is manufactured (FIG. 6).
(See (a)).

Next, the semiconductor wafer 54 of the scribing portion 57 is removed by etching to form a semiconductor wafer removing portion 58, and then the metal layer 52 is etched to form a groove 60 (see FIG. 6B).

Subsequently, the metal layer 52 is opposed to the laminated body 5
6 is attached to the expanding sheet 62. After that, from the semiconductor wafer 54 side, the metal layer 5 of the scribing part 57 is
2 is irradiated with the laser beam 64, and the metal layer 5 in that portion is irradiated.
2 is cut to form a scribing hole 68 (FIG. 6).
(See (c)). The metal layer 52 of the scribing part 57 irradiated with the laser beam 64 melts, and the melted metal forms a melt-solidification part 66 due to surface tension. As a result,
A scribing hole 68 is formed in the metal layer 52.

Since the conventional semiconductor device and laser scribing method are configured as described above, there are problems as described below. Since the laser beam absorptivity of the metal layer 52 is small (about 5.3% in the case of Au), when the processing speed is increased (the relative movement speed between the laser beam 64 and the laminated body 56 is increased), a splash ( Melted and scattered material) is generated. This splash is a semiconductor wafer 54
Since the circuit pattern formed on the top is short-circuited, the yield rate of individual scribed semiconductor chips is high.
Is reduced. Therefore, the processing speed of scribing cannot be increased, and thus the throughput cannot be increased.

Further, the groove 60 formed in the scribing portion of the metal layer 52 for increasing the scribing processing speed.
If the depth is increased, the metal layer 52 forming the bottom of the groove 60 becomes thin and the mechanical strength of the metal layer 52 becomes insufficient, so that the wafer is likely to be deformed or damaged during handling.

The present invention has been made to solve the above problems. In laser scribing, a semiconductor device can be scribed into individual semiconductor chips at a high processing speed without causing a splash from the scribing portion. It is an object to obtain a semiconductor device and a laser scribing method that can be performed.

[0014]

According to a first aspect of the present invention, there is provided a semiconductor device comprising a laminated body of a semiconductor wafer and a metal layer, wherein a scribing portion has a semiconductor wafer removing portion and a groove formed in the metal layer. And a layer having a higher absorptance of laser beam energy than the inside of the metal layer is formed on the surface of the metal layer exposed to the scribing portion.

A semiconductor device according to a second aspect of the invention is
A layer in which the absorption rate of laser beam energy is higher than that inside the metal layer is formed by a layer made of metal having an absorption rate of laser beam energy of 20% or more.

A semiconductor device according to a third aspect of the invention is
The semiconductor wafer is made of GaAs, the metal layer is made of Au, and Ni is used as a metal having a laser beam energy absorption rate of 20% or more.

A semiconductor device according to a fourth aspect of the invention is
A layer having a higher absorption rate of laser beam energy than the inside of the metal layer is a layer whose surface is roughened.

A semiconductor device according to the invention of claim 5 is
The semiconductor device according to claim 4, wherein the semiconductor wafer is G.
It is made of aAs and the metal layer is made of Au.

According to a sixth aspect of the present invention, there is provided a laser scribing method comprising a laminated body of a semiconductor wafer and a metal layer, wherein the scribing section comprises a semiconductor wafer removing section and a groove formed in the metal layer. In the laser scribing method of irradiating the scribing section with a laser beam to divide the semiconductor chip into individual semiconductor chips, the incident angle of the laser beam incident on the scribing section is 60.
The angle is set to be not less than 90 ° and less than 90 °.

In the laser scribing method according to the seventh aspect of the present invention, the semiconductor wafer is made of GaAs, the metal layer is made of Au, and the YAG laser beam is used as the laser beam for irradiating the scribing portion.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described below. Embodiment 1. FIG. 1 is a diagram showing a cross section in the vicinity of a scribing portion of a semiconductor device according to a first embodiment of the present invention. In the figure, 12 is a metal layer constituting a heat sink, which is made of, for example, gold (Au) or the like. Reference numeral 14 is a semiconductor wafer having a circuit pattern formed on its surface, for example, S
i, GaAs, etc. 16 is a laminated body of the metal layer 12 and the semiconductor wafer 14. 17 is a scribing section,
Reference numeral 18 denotes a semiconductor wafer removing section which removes the semiconductor wafer 14 of the scribing section 17 by etching. Two
Reference numeral 0 represents a groove formed in the metal layer 12 of the scribing portion 17 by etching. 22 is a semiconductor wafer removing unit 1
8 is a laser beam absorption layer (a layer having a higher absorption rate of laser beam energy than that inside the metal layer) formed on the surface of the metal layer 12 exposed at 8, and is made of, for example, a nickel (Ni) layer.

An example of the semiconductor device according to the first embodiment will be described in detail below. The semiconductor wafer 14 is 30 μm
Made of GaAs with the thickness
(Physical Vapor Deposition
n) method or plating method was used to deposit Au to a thickness of 30 μm to form the metal layer 12 constituting the heat sink. As a result, a laminated body 16 of the metal layer 12 and the semiconductor wafer 14 was produced.

Next, the semiconductor wafer 14 in the scribing section 17 was wet-etched with a mixed solution of hydrogen peroxide and tartaric acid to form a 100-μm wide semiconductor wafer removing section 18 along the scribing line.

Next, the metal layer 12 of the scribing part 17
The width is 100μ due to ion milling with Ar ions.
A groove 20 having a depth of m and a depth of 27 μm was formed along the scribing line.

Then, a nickel (Ni) layer having a thickness of 2 μm is electrolessly plated on the surface of the metal layer 12 exposed in the semiconductor wafer removing section 18 to form a laser beam absorbing layer 22.
Was formed. The reflectance of Ni with respect to the YAG laser beam is 72%, that is, the absorptance is 28%. Since the absorption rate of Au for the YAG laser beam is about 5.3%, the absorption of the metal layer 12 for the YAG laser beam is performed by forming the laser beam absorption layer 22 of Ni on the surface of the metal layer 12 of Au. I was able to increase the rate.

In the conventional semiconductor device, if the metal layer 52 forming the bottom of the groove 60 provided in the metal layer 52 of the scribing portion 57 is thinned as shown in FIG. 6, the mechanical strength of the metal layer 52 becomes insufficient. However, there is a problem that the wafer is likely to be deformed or damaged during handling. Also in the semiconductor device according to the first embodiment, the scribing unit 17
The thickness of the metal layer 12 forming the bottom of the groove 20 provided in the metal layer 12 was 3 μm, which was considerably thin, but the wafer was not deformed or damaged during handling. The reason is that, in the semiconductor device according to the first embodiment, the metal layer 12 having a thickness of 3 μm forming the bottom of the groove 20 is composed of an Au layer having a thickness of 1 μm and a Ni layer having a thickness of 2 μm, and Ni is different from Au. It is considered that because the hardness is high, the metal layer 12 forming the bottom of the groove 20 has sufficient mechanical strength to withstand wafer handling.

Next, the operation will be described. As shown in FIG. 1, the laminated body 16 in which the semiconductor wafer removing portion 18 and the groove 20 were formed was attached to an expand sheet (not shown) so as to face the metal layer 12. As the expand sheet, for example, a vinyl chloride-based “ELEP FOLDER” (trade name, manufactured by Nitto Kogyo) is used.

The laser beam absorbing layer 22 made of Ni formed on the surface of the metal layer 12 exposed in the semiconductor wafer removing portion 18 is irradiated with a YAG laser beam from a direction perpendicular to the surface of the laser beam absorbing layer 22 to form Ni. The scribing portion 17 having a laminated structure with Au was melted in a width of about 80 μm to form a scribing hole. Used YAG
The laser has an oscillation wavelength of 1.06 μm, a Q-switch frequency of 20 kHz, and an average output of 2 W. While irradiating the laser beam emitted from the YAG laser with a lens having a focal length of 50 mm so that the focal position thereof coincides with the surface of the laser beam absorption layer 22, the laser beam and the laminated body 1
6 and 6 were moved relative to each other at a speed of 0.8 m / min.

As a result of scribing the laminated body 16 shown in FIG. 1 using the YAG laser beam as described above,
Ni and Au were only melted in the laser beam irradiation part, and dust such as splash and vapor was not generated.
Further, during wafer handling, the wafer was neither deformed nor damaged.

As described above, according to the first embodiment, the laser beam absorption layer 22 made of Ni having a higher energy absorption rate of YAG laser beam than Au is formed on the surface of the scribing portion 17 irradiated with the YAG laser beam. Therefore, the YAG is attached to the scribing portion 17 which is fused by the laser beam through the laser beam absorption layer 22.
The laser beam can be efficiently incident. As a result, it is possible to suppress the generation of splash during laser scribing. Further, since Ni has higher rigidity than Au, even if the wall thickness of the scribing portion 17 is thinned, the wafer is unlikely to be deformed or damaged during handling. From the above, according to the first embodiment, the processing speed can be increased without lowering the yield in the scribing process, and thus the throughput can be improved.

Next, the mechanism of laser scribing according to the first embodiment will be described. FIG. 2 is a schematic diagram showing the positional relationship between the energy density distribution curve of the laser beam during melting and cutting of the scribing portion and the metal layer. 2 in the figure
4 is the energy density distribution curve of the laser beam, 26 is the metal layer exposed at the scribing portion, 28 is the energy density of the laser beam required to melt the metal layer 26, and 30 is the energy of the laser beam required to vaporize the metal layer 26. Density, 32
Is a melting portion formed at the end of the metal layer 26 irradiated with the laser beam, and 34 is a splash scattered from the melting portion 32.

As can be seen from FIG. 2 (a), the energy density of the laser beam applied to the melting portion 32 formed at the end of the metal layer 26 during fusing is determined by the energy density 28 required for melting and evaporation. Splash will not occur if maintained between the required energy density 30. Here, when the output of the laser beam is increased to increase the scribing processing speed, the energy density distribution curve becomes steep as shown in FIG. As a result, the spatial distance between the energy density 28 required for melting and the energy density 30 required for evaporation (horizontal distance in the figure) is shortened, so that the melting portion 3
A laser beam having an energy density higher than the energy density 30 required for evaporation is applied to the end portion of 2, and a splash 34 is generated from the melting portion 32.

In the semiconductor device according to the first embodiment, as shown in FIG. 1, a laser beam absorption layer 22 made of Ni is formed on the surface of the metal layer 12 exposed in the scribing portion 17. Since Ni has a higher absorption rate of laser beam energy than Au, the scribing section 17 made of a laminated body of Ni and Au has both the energy density required for melting and the energy density required for evaporation more than those made of Au alone. Will also be lower. Therefore, the required processing speed can be achieved without increasing the output of the laser beam, so that the state of FIG. 2A can be continuously maintained, and the scribing unit 17 can be operated as shown in FIG. Since it is not necessary to irradiate a high-power laser beam so as to have a steep energy density distribution curve shown, the splash 34 does not occur.

For comparison, a semiconductor device was prepared in which the metal layer of the scribing portion was composed of Au alone as in the conventional case, and the scribing portion was provided with Y under the same conditions as described above.
Laser scribing was performed by irradiating an AG laser beam. As a result, a large amount of splash was generated from the fused portion during laser scribing. In order to suppress the generation of splash, it was necessary to reduce the processing speed to 0.3 m / min or less. Compared with the case of the first embodiment described above, 0.3 / 0.8 = 0.375, that is, the processing speed is reduced by about 63%. Further, in a semiconductor device in which the metal layer of the scribing portion is made of Au alone, the wafer is deformed or damaged during handling, and many of the individually divided semiconductor chips become defective products, resulting in a decrease in yield. .

Embodiment 2. 3 is a diagram showing a cross section in the vicinity of a scribing portion of a semiconductor device according to a second embodiment of the present invention. In the figure, portions corresponding to those in FIG. Reference numeral 36 denotes a roughened layer (a layer having a higher absorption rate of laser beam energy than the inside of the metal layer) formed on the surface of the metal layer 12 exposed in the semiconductor wafer removing section 18, which acts to absorb the laser beam. To do.

Hereinafter, an example of the semiconductor device according to the second embodiment will be described in detail with reference to FIG. The semiconductor wafer 14 is made of GaAs having a thickness of 30 μm, and after a circuit pattern is formed on the front surface by a normal wafer process, the back surface is machined to form irregularities of several μm level to roughen it. Au was deposited to a thickness of 30 μm on the back surface of the roughened semiconductor wafer 14 by a plating method to form a metal layer 12 which forms a heat sink. As a result, a laminated body 16 of the metal layer 12 and the semiconductor wafer 14 was produced.

Next, the semiconductor wafer 14 of the scribing section 17 was wet-etched using a mixed solution of hydrogen peroxide and tartaric acid to form a semiconductor wafer removing section 18 having a width of 100 μm along the scribing line. As a result, the roughened layer 36 of the metal layer 12 was exposed in the semiconductor wafer removing section 18.

Subsequently, the metal layer 1 of the scribing part 17
2 by ion milling with Ar ion, width 100μ
A groove 20 of m and 23 μm in depth was formed along the scribing line.

Next, the operation will be described. As shown in FIG. 3, the laminated body 16 in which the semiconductor wafer removing portion 18 and the groove 20 were formed was attached to an expand sheet (not shown) with the metal layers 12 facing each other. As the expand sheet, for example, a vinyl chloride-based “ELEP FOLDER” (trade name, manufactured by Nitto Kogyo) is used.

The surface roughening layer 36 exposed in the semiconductor wafer removing section 18 is irradiated with a YAG laser beam from a direction perpendicular to the surface of the surface roughening layer 36, and the scribing section 17 is moved to about 80.
It was melted in a width of μm to form a scribing hole. The YAG laser used has an oscillation wavelength of 1.06 μm, a Q-switch frequency of 30 kHz, and an average output of 3.0 W. The laser beam emitted from the YAG laser has a focal length of 5 so that its focal position coincides with the surface of the roughening layer 36.
While irradiating with a 0 mm lens, the laser beam and the laminated body 16 were relatively moved at a speed of 0.3 m / min.

As a result of scribing the laminated body 16 shown in FIG. 3 using the YAG laser beam as described above,
At the laser beam irradiation portion, the metal layer 12 made of Au was only melted, and dust such as the splash 34 and vapor was not generated.

As described above, according to the second embodiment, since the roughened layer 36 is formed on the surface of the metal layer 12 forming the scribing portion 17 irradiated with the YAG laser beam, this roughened layer is formed. The YAG laser beam can be efficiently incident on the scribing unit 17 that is fused by the laser beam through the line 36. As a result, it is possible to suppress the generation of the splash 34 during the laser scribing. From these things, according to the second embodiment, the processing speed can be increased without lowering the yield in the scribing process, and thus the throughput can be improved.

For comparison, the roughened layer 36 was not formed,
A semiconductor device was prepared in which the metal layer of the scribing portion was made of flat Au as in the conventional case, and the scribing portion 17 was irradiated with the YAG laser beam under the same conditions as described above to perform laser scribing. As a result, a large amount of splash was generated from the fused portion during laser scribing. In order to suppress the generation of splash, it was necessary to reduce the processing speed to 0.1 m / min or less. Compared with the case of the second embodiment described above, 0.1 / 0.3
= 0.333, that is, the processing speed is reduced by about 67%.

Embodiment 3. FIG. 5 is a cross-sectional perspective view of an essential part showing a scribing method according to a third embodiment of the present invention. In the figure, 12 is a metal layer forming a heat sink, which is made of Au having a thickness of 30 μm. Reference numeral 14 denotes a 30 .mu.m thick semiconductor wafer having a circuit pattern formed on its surface, which is made of, for example, GaAs. Reference numeral 17 denotes a scribing section, and 18 denotes a semiconductor wafer removing section obtained by removing the semiconductor wafer 14 of the scribing section 17 by etching. Reference numeral 20 is a groove formed by ion milling the metal layer 12 of the scribing portion 17 with Ar ions.
Reference numeral 38 is an expand sheet to which a laminated body including the metal layer 12 and the semiconductor wafer 14 is attached, and is made of, for example, a vinyl chloride material. Reference numeral 40 denotes a YAG laser beam (laser beam) that irradiates and melts the metal layer 12 exposed at the scribing portion, and 42 denotes an optical axis of the YAG laser beam 40. Reference numeral 44 is a normal line of the surface of the metal layer 12 exposed in the scribing portion 17. Reference numeral 46 denotes the metal layer 1 exposed on the scribing part 17 irradiated with the YAG laser beam.
2 is the focus position on the surface. θ is the YAG laser beam 40
Angle of incidence, that is, the optical axis 42 of the YAG laser beam 40
Is the angle formed by the normal line 44.

Next, the operation will be described. The focus position 46 on the surface of the metal layer 12 exposed at the semiconductor wafer removing portion 18
Then, the YAG laser beam 40 was irradiated. At this time, Y
The incident angle of the YAG laser beam 40 is set so that the angle (incident angle) θ formed by the optical axis 42 of the AG laser beam 40 and the normal line 44 is θ> 60 °. The YAG laser used has an oscillation wavelength of 1.06 μm and a Q-switch frequency of 30 k.
Hz and an average output of 3.0 W. The YAG laser beam 40 emitted from the YAG laser is focused on its focus position 46.
The focal length is 50 mm so that is aligned with the surface of the metal layer 12.
YAG laser beam 4 while irradiating using the lens of
0 and the semiconductor device were relatively moved at a speed of 0.3 m / min.

Under the above conditions, when the incident angle θ of the YAG laser beam 40 was set to θ = 80 ° and scribing was carried out, the metal layer 12 was fused and cut along the scribing line with a width of about 80 μm, and the scribing hole was formed. Been formed.

As a result of the scribing, Au forming the metal layer 12 irradiated with the YAG laser beam 40 was only melted, and dust such as splash 34 and vapor was not generated.

As described above, according to the third embodiment, by setting the incident angle θ so that the metal layer 12 absorbs the energy of the YAG laser beam 40 for scribing most, the scribing section 17 is provided. Since the energy beam can be efficiently incident, the fusion zone 3
It is possible to suppress the generation of the splash 34 in 2. The incident angle θ of the YAG laser beam 40 is θ>
When set to 60 °, YA in the scribing unit 17
The absorption rate of the G laser beam 40 increases. Therefore,
The incident angle θ of the YAG laser beam 40 is effectively set to 60 ° or more.

As described above, according to the third embodiment, the processing speed can be increased without lowering the yield in the scribing process, so that the throughput is improved.

In the above-described first to third embodiments, the metal layer 12 is made of Au and the semiconductor wafer 14 is made of Ga.
Although an example of scribing a semiconductor device made of As using a YAG laser beam has been shown, the metal layer 12 may be a metal such as Al or Cu, and the semiconductor wafer 14 is S.
i or the like may be used. In addition to the YAG laser, an energy beam such as a laser beam emitted by another solid-state laser can be used.

[0051]

As described above, according to the first aspect of the present invention, the scribing portion of the semiconductor device, which is a laminated body of the semiconductor wafer and the metal layer, has the groove formed in the semiconductor wafer removing portion and the metal layer. The surface of the metal layer exposed in the scribing section is formed so as to form a layer having a higher absorption rate of laser beam energy than the inside of the metal layer, so that high yield and high throughput of the scribing process can be achieved. There is an effect that can be realized.

According to a second aspect of the present invention, in the semiconductor device according to the first aspect, a layer having a laser beam energy absorption rate higher than that inside the metal layer is formed of a metal having a laser beam energy absorption rate of 20% or more. Since the laser fusing part is configured to be formed of a layer consisting of, it is possible to suppress generation of dust such as splash from the laser fusing part, and thus it is possible to increase the laser fusing speed. As a result, there is an effect that the division processing speed into individual semiconductor chips is improved.

According to a third aspect of the present invention, in the semiconductor device according to the second aspect, the semiconductor wafer is made of GaAs, the metal layer is made of Au, and the absorption rate of laser beam energy is 20% or more. Is used, there is an effect that the scribing speed of the high frequency semiconductor device is improved.

According to a fourth aspect of the present invention, in the semiconductor device according to the first aspect, a layer having a higher absorptance of laser beam energy than the inside of the metal layer is a layer whose surface is roughened. Since it is configured to be formed, there is an effect that the laser fusing speed can be increased. As a result,
This has the effect of increasing the dividing processing speed into individual semiconductor chips.

According to the invention of claim 5, in the semiconductor device of claim 4, since the semiconductor wafer is made of GaAs and the metal layer is made of Au, the scribing speed of the high frequency semiconductor device is improved. Has the effect of

According to the sixth aspect of the present invention, the scribing portion is composed of a laminated body of a semiconductor wafer and a metal layer.
In the laser scribing method of irradiating the scribing part of the semiconductor device including the semiconductor wafer removing part and the groove formed in the metal layer with a laser beam to divide the semiconductor chip into individual semiconductor chips, the laser beam incident on the scribing part is Since the incident angle is set to 60 ° or more and less than 90 °, it is possible to suppress the generation of dust such as splash from the laser fusing part, and thus it is possible to increase the laser fusing speed. As a result, there is an effect that the division processing speed into individual semiconductor chips is improved.

According to the invention of claim 7, in the laser scribing method of claim 6, the semiconductor wafer is made of GaAs, the metal layer is made of Au, and a YAG laser beam is used as a laser beam for irradiating the scribing portion. With this structure, the scribing speed of the high frequency semiconductor device can be improved.

[Brief description of drawings]

FIG. 1 is a diagram showing a cross section in the vicinity of a scribing portion of a semiconductor device according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a positional relationship between an energy density distribution curve of a laser beam during melting and cutting of a scribing portion and a metal layer.

FIG. 3 is a diagram showing a cross section in the vicinity of a scribing portion of a semiconductor device according to a second embodiment of the present invention.

FIG. 4 is a detailed explanatory diagram of an example of a semiconductor device according to a second embodiment.

FIG. 5 is a perspective sectional view showing an essential part of a scribing method according to a third embodiment of the present invention.

FIG. 6 is a diagram showing each step of a scribing method by a laser fusing method according to the previous application.

[Explanation of symbols]

12 metal layers, 14 semiconductor wafers, 16 laminated bodies, 1
7 scribing part, 18 semiconductor wafer removing part, 2
0 groove, 22 laser beam absorption layer (layer having higher absorption rate of laser beam energy than inside metal layer), 36 roughened layer (layer having higher absorption rate of laser beam energy than inside metal layer), 40 YAG laser Beam (laser beam).

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masahiro Tamaki 2-3-3 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation (56) References JP-A-9-323300 (JP, A) (58) Survey Areas (Int.Cl. ⁷ , DB name) H01L 21/301 B23K 26/00

Claims (7)

(57) [Claims] 1. A semiconductor device comprising a laminated body of a semiconductor wafer and a metal layer, wherein a scribing section comprises a semiconductor wafer removing section and a groove formed in the metal layer, and the metal layer exposed at the scribing section. A semiconductor device in which a layer having a higher absorptance of laser beam energy than the inside of the metal layer is formed on the surface of. 2. The semiconductor device according to claim 1, wherein the layer having a higher absorption rate of laser beam energy than that inside the metal layer is a layer made of a metal having an absorption rate of laser beam energy of 20% or more. . 3. The semiconductor wafer is made of GaAs, the metal layer is made of Au, and the absorption rate of the laser beam energy is 2.
The 0% or more metal is Ni.
The semiconductor device described. 4. The semiconductor device according to claim 1, wherein the layer having a higher absorption rate of laser beam energy than the inside of the metal layer is a layer whose surface is roughened. 5. The semiconductor device according to claim 4, wherein the semiconductor wafer is made of GaAs and the metal layer is made of Au. 6. A laser beam is applied to the scribing part of a semiconductor device, which comprises a laminated body of a semiconductor wafer and a metal layer, and the scribing part comprises a semiconductor wafer removing part and a groove formed in the metal layer. A laser scribing method for a semiconductor device divided into individual semiconductor chips, wherein an incident angle of the laser beam incident on the scribing portion is 60 ° or more and less than 90 °. 7. The laser scribing method according to claim 6, wherein the semiconductor wafer is made of GaAs, the metal layer is made of Au, and the laser beam for irradiating the scribing portion is a YAG laser beam.