JP3305399B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a semiconductor device having a cleaving step for forming a high-precision plane, and more particularly to a method of manufacturing a semiconductor laser capable of preventing the occurrence of wafer cracks without hindering cleavage. It is about.

[0002]

2. Description of the Related Art FIG. 4 is a process chart showing a conventional method for manufacturing a semiconductor laser chip. In the figure, reference numeral 200 denotes a wafer on which a multilayer epitaxial growth layer 2 is formed on a semiconductor substrate 1, 3 denotes a surface electrode patterned on a chip unit of a semiconductor laser formed on the wafer 200, 4 denotes a back surface of the substrate 1 The back electrode 5, formed after grinding or polishing the side, was formed by cleaving the wafer 200.
A bar in which the chips are arranged in a horizontal line, 7 is a semiconductor laser element formed by indexing the bar 5, and 6 is a high-precision plane formed by this cleavage, and serves as a mirror of the semiconductor laser.

Next, the manufacturing process will be described. Fig. 4 (a)
On the surface of the wafer 200 on which the epitaxial growth layer 2 shown in FIG. 4 is formed, as shown in FIG. 4B, a front-side electrode 3 patterned for each individual chip is formed. The size of a semiconductor laser chip is a typical one with a length of 250 to
The width is 500 μm and the width is 300 to 600 μm.

[0004] Next, as shown in FIG.
The back surface of the wafer 200 is ground or polished until the thickness of the wafer 200 becomes about 100 μm. The thickness before shaving depends on the wafer size, but is about 300 to 600 μm. In a semiconductor laser, a pair of mirrors is formed by cleaving, that is, by breaking a wafer along a certain crystal axis, and the light reflected by the mirrors is amplified between the mirrors to cause laser oscillation. However, in order to facilitate cleavage, the wafer thickness must be 100
It needs to be less than μm. However, when the thickness is about 100 μm, the wafer 200 itself is very easily broken and processing becomes difficult. Therefore, processing such as formation of the electrode 3 on the front side of the wafer 200, that is, the side on which the epitaxial layer 2 is formed, is performed by grinding or polishing. Done before. After the grinding or polishing is completed, the back surface electrode 4 is formed on the back surface of the wafer 200. After the completion of the wafer process, as shown in FIG. 4D, the chips are indexed into bars 5 arranged in a row by cleavage. The high-precision plane 6 formed by the cleavage becomes a mirror surface. Finally, the individual semiconductor chips are completed as shown in FIG. 4 (e).

[0005]

The conventional method of manufacturing a semiconductor laser chip is configured as described above. According to such a process, when the wafer size is about 2 to 3 cm square, the wafer thickness is reduced. Although handling is possible even after being ground or polished to 100 μm, GaAs, which is often used in semiconductor lasers, is
The substrate is very easily broken, and the wafer is broken in a back surface process including grinding or polishing, for example. In a conventional semiconductor laser manufacturing process, a liquid phase epitaxy (LPE) method is used in an epitaxial process. In this growth method, a rectangular wafer cannot be used unless it is a rectangular wafer. Since the formation of a uniform epitaxial growth layer over the entire surface was limited to a square of 2 × 3 cm, there was no particular problem with such a manufacturing method. However, recently, the epitaxial process has been performed by a vapor phase growth method (MB
(E, MOCVD) has become mainstream, so there is no longer any restriction on the wafer size. For mass production of semiconductor laser devices, the use of large wafers is desired. However, there is a problem in handling as described above, and therefore, it has been difficult to increase the wafer size and improve mass productivity.

On the other hand, most wafers used in semiconductor devices typified by LSIs have a circular shape with a wafer size of 3 inches or more. If these wafers are too thin,
In the manufacturing process of GaAsIC (gallium arsenide integrated circuit), after the wafer surface processing step is completed, as shown in FIG.
A back surface process including grinding by applying a wax 9 to the wafer is performed so that the wafer is not broken in the middle.
However, if the wafer is peeled off from the glass plate as it is, it will eventually break when the wafer is peeled off from the glass plate. Therefore, by forming the plating layer 10 on the back surface of the polished wafer as shown in FIG. It is used as a reinforcing material for prevention.

However, in the method of manufacturing a semiconductor laser, for example, a large-sized circular wafer is used, the wafer is attached to a glass plate, the back surface is processed, and plating for reinforcing the back surface is performed in the same manner as in the above-described method of manufacturing a GaAs IC. If a process of forming and peeling a wafer from a glass plate is used, cleavage cannot be performed this time. This is because the plating does not break as cleanly as crystals. Therefore, increasing the wafer size to improve the mass productivity of the semiconductor laser has a problem in the process.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to manufacture a wafer which does not crack even if the wafer size is increased and which does not hinder cleavage. It is an object of the present invention to provide a method of manufacturing a semiconductor device which can be performed.

[0009]

According to a method of manufacturing a semiconductor device according to the present invention, after a step of bonding the front surface of a wafer to a glass plate and processing the back surface, a peripheral portion of the back surface of the wafer other than a region where a semiconductor laser or the like is to be formed. Only the reinforcing plating is formed.

In the method of manufacturing a semiconductor device according to the present invention, a scribe line for indexing is provided in a portion where the plating is formed.

In the method of manufacturing a semiconductor device according to the present invention, a magnetic material is used as a material for the plating for reinforcement.

[0012]

According to the present invention, a plating area is provided on a peripheral portion of the wafer other than the area where the semiconductor laser or the like is to be formed, so that the wafer can be prevented from cracking when the wafer is peeled off from the glass plate. The backside processing of the wafer attached to a glass plate can be performed, and mass production of a semiconductor laser chip using a large wafer such as a circular wafer having a diameter of 3 inches or more used for an LSI or the like can be performed.

Further, since a scribe line for indexing is provided in a portion where the plating is formed, indexing of a semiconductor laser region or the like can be easily performed.

By using a magnetic material for plating,
Since the entire surface of the wafer can be sucked and handled with an electromagnet, the handling force is dispersed without concentrating on minute parts on the wafer as compared with the case of handling by hand using tweezers etc. Therefore, it is possible to prevent chipping or cracking of the wafer.

[0015]

【Example】

Embodiment 1 FIG. FIGS. 1A to 1D are process diagrams showing a method for manufacturing a semiconductor laser chip according to a first embodiment of the present invention. In the drawing, reference numeral 100 denotes a wafer having a diameter of about 3 inches having a plurality of epitaxial layers formed on its surface, and this surface is attached to a glass plate 8 with wax. Reference numeral 11 denotes a region on the wafer 100 on which plating for preventing cracking of the wafer is formed other than the region serving as the semiconductor laser, and 12 denotes a region serving as the semiconductor laser.

Next, the manufacturing process of the semiconductor laser chip according to the present embodiment will be described. As shown in FIG.
Wafer 100, which has been subjected to processing such as electrode formation on the front surface, is attached to glass plate 8 with wax so that the front surface is bonded, and in this state, back surface processing such as cutting the wafer thickness to about 100 μm is performed.

Next, as shown in FIG. 1B, only the peripheral portion 11 other than the region 12 to be a semiconductor laser is plated with gold or the like. Plating is performed by forming a plating pattern by a transfer process, immersing the wafer in a plating solution, and flowing an electric current between the solution and the wafer. Here, the plating thickness is 2μ
m or more is desirable.

After the above-described processing step on the back side is completed, FIG.
As shown in FIG. 1, after the wafer 100 is peeled off from the glass plate 8, as shown in FIG. As is the case with the final form, a rectangular and large-area wafer 12 is obtained.

In the case of a circular wafer, the surrounding portion is generally a handling portion, and chipping and cracking are apt to occur at this portion, and particularly when the wafer is peeled off from a glass plate, it is most easily broken. In many cases, cracks entering the peripheral portion extend inside and the entire wafer is broken. However, in the present embodiment, by providing the plating region 11 around the wafer 100, the cracking of the wafer can be remarkably reduced.

As described above, in this embodiment, since the plating is performed on the peripheral portion other than the region 12 where the semiconductor laser is formed, the wafer 100 can be peeled off from the glass plate without causing the wafer crack. Wafer 100
Can be applied to the glass plate 8 to perform back surface processing such as polishing, and there is no adverse effect on cleavage, so that a semiconductor laser can be manufactured using a large wafer.

Embodiment 2 FIG. FIG. 3 is a view for explaining a method of manufacturing a semiconductor device according to a second embodiment of the present invention. In the second embodiment, a pattern of a portion which is not plated in a stripe shape is previously inserted in a transfer process for a plating pattern. That is, the scribe line 13 for indexing is inserted into the plating 11.

If the entire periphery of the semiconductor laser region 12 on the wafer is surrounded by the plating 11, it is difficult to determine the semiconductor laser region 12. Therefore, as shown in FIG. The semiconductor laser region 12 can be easily indexed by inserting the scribe line 13 for use.

Embodiment 3 FIG. In the third embodiment, the plating 11 in the first embodiment is formed of a magnetic material. In this embodiment, the plating 1
After the wafer 1 is formed, the wafer can be handled by attracting the peripheral portion of the wafer with an electromagnet. Therefore, the particles are dispersed without being concentrated on the appropriate portions, and the occurrence of chipping or cracking can be prevented.

[0024]

As described above, according to the present invention, 2-3
In the process after cutting the thickness of a large wafer for semiconductor lasers of cm square or more to about 100 μm,
Since the wafer is reinforced by forming plating only in the peripheral region of the wafer, it is possible to make it difficult for the wafer to crack due to handling or the like, and to easily determine the region to be a semiconductor laser. Can be easily performed, and the size of the wafer can be increased.
This has the effect of improving the mass productivity of semiconductor laser chips and providing semiconductor lasers at low cost.

Further, according to the present invention, since the scribe line is provided in the portion where the plating is formed, there is an effect that the region such as the semiconductor laser region can be easily indexed.

Further, according to the present invention, by forming a plating with a magnetic material only on the peripheral area of the semiconductor laser wafer, handling by an electromagnet becomes possible, and cracking of the wafer during handling can be prevented. There is.

[Brief description of the drawings]

FIG. 1 is a process chart showing a method for manufacturing a semiconductor laser chip according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a state in which a conventional gallium arsenide integrated circuit wafer is attached to a glass plate.

FIG. 3 is a plan view showing a plating pattern on the back surface of a wafer of a semiconductor laser according to a second embodiment of the present invention.

FIG. 4 is a process chart showing a conventional method for manufacturing a semiconductor laser chip.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor substrate 2 Epitaxial growth layer 3 Front surface electrode 4 Back surface electrode 5 Bar 6 Cleaved surface 7 Semiconductor laser element 8 Glass plate 9 Wax 10 Plating layer 11 Plating area other than area used as semiconductor laser 12 Area used as semiconductor laser 13 Scribe line 100 Wafer 200 wafers

Claims (4)

(57) [Claims] 1. A step of grinding or polishing the back surface of a wafer until the wafer has a predetermined thickness, and thereafter, a step of determining a region where semiconductor devices are formed from the wafer and forming a high-precision plane by cleavage. The method of manufacturing a semiconductor device according to claim 1, further comprising, after the step of grinding or polishing the back surface of the wafer, a step of forming a plating on a peripheral region other than the region where the semiconductor device is formed on the back surface of the wafer. Manufacturing method of a semiconductor device. 2. The method for manufacturing a semiconductor device according to claim 1, wherein said plating is made of a magnetic material. 3. The method of manufacturing a semiconductor device according to claim 1, wherein a scribe line for indexing is formed in a plated area on the back surface of the wafer. Method. 4. The method of manufacturing a semiconductor device according to claim 1, wherein said semiconductor device is a semiconductor laser.