JPS6116592A - Manufacture of chip of semiconductor laser - Google Patents

Abstract

PURPOSE:To improve productivity while enhancing yield on assembly and reliability on performance by conducting cleavage, the coating of an anti-oxidizing film, chopping and the separation of chips in a series at every unit of wafers stuck to an adhesive sheet. CONSTITUTION:A surface, to whic marking flaws 7 for the starting points of cleavage are formed, in a blank wafer 1 is coated with an alkali-soluble positive resist. The wafer 1 stuck onto an adhesive sheet 8 is cloven and treated by applied pressure from the outer surface of the sheet 8 under the state in which the forming surface of the marking flaws 7 is exposed. Several wafer small-piece is chopped at regular pitches in the longitudinal direction of the small pieces on the adhesive sheet 8 to shape a chip 19 group, and the adhesive sheet 8 is stretched and each chip 19 is separated mutually. The whole surfaces of the exposed surfaces of the chip 19 group separated on the adhesive sheet 8 are coated with anti-oxidizing films 15. The positive resists 14 on several chip 19 are dissolved and removed by alkali, and the chips are washed by water and dried.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a semiconductor laser chip.
Specifically, the process is characterized by applying an anti-oxidation coating to the separated end faces.

[Prior art]

Semiconductor laser chips are formed by cleaving a raw material wafer and cutting the obtained long thin wafer pieces into pieces in the longitudinal direction.In order to extend the life of the semiconductor laser by preventing oxidation of the cleavage plane, which becomes the light-emitting end face, Si3N.

Alternatively, it is coated with a film such as Al2O3.

In this case, conventionally, an end face coating was applied to each small wafer piece that was cleaved from the wafer, and then the small wafer pieces were cut into pieces at a predetermined pitch in the longitudinal direction.

[Problem that the invention seeks to solve]

In the above-mentioned means, since each wafer piece is handled one by one, it takes time to load and unload the coating device, resulting in low productivity.

Further, as shown in FIG. 10, the chip obtained by the above method has an antioxidant coating 15 formed only on the cleavage surface S, and no coating is applied on both side surfaces T, which are narrow sections. Since the PU joint of the chip body was exposed, when the chip surface was fused to a heat sink etc.
The N-junction may be short-circuited at the side surface of the chip due to the brazing material wrapping around the chip, resulting in a problem of lower assembly yield and performance reliability.

By improving the coating means for preventing edge oxidation, the present invention enables wafer-by-wafer processing, enables highly productive chip manufacturing, and improves assembly yield and performance reliability. This is an attempt to provide a chip manufacturing method that can.

[Failure to solve the problem]

Therefore, in the present invention, a method including the following steps was adopted.

■ The process of coating the surface of the raw wafer where the scribe scratches for cleavage starting points are to be formed with an alkali-soluble PosiRestra coating.

(2) A step of cleaving the wafer adhered to the adhesive sheet with the surface on which the scratches are formed exposed by applying pressure from the outer surface of the sheet.

■ A process in which each wafer piece is cut into pieces at a predetermined pitch in the longitudinal direction on an adhesive sheet to form a group of chips.

■ The process of stretching the adhesive sheet and separating each chip from each other.

■ The process of coating the entire exposed surface of a group of chips separated on an adhesive sheet with an antioxidant film.

■ Process of dissolving and removing the positive rest of each chip with alkali, washing with water, and drying.

[Effect]

According to the above method, cleaving, coating with an antioxidant film, shredding, and separation of chips are performed in a series for each wafer attached to the adhesive sheet. Furthermore, not only the cleavage planes of the separated chips but also their side surfaces are coated with an antioxidant coating.

〔Example〕

Below, each step of the method of the present invention will be sequentially explained based on the drawings.

■ Cleavage treatment process (see Figures 1 to 3) The material of the semiconductor laser with the electrode surface facing up is the positive resist (for example, A Z 1) that can be dissolved in an alkali in advance.
A protective film (350) is coated on the upper surface of the wafer 1, and the wafer 1 is suctioned and fixed on the upper surface of a movable table 3 equipped with a vacuum chuck 2, and is intermittently moved laterally at a constant pitch. An aluminum foil 4 having a thickness of about 15 μm is attached to the upper surface of the wafer 1 coated with a protective film, and the upper surface of the front edge of the wafer 1 is slightly exposed than the front edge of the aluminum foil 4.

A diamond scriber 5 that is driven up and down and back and forth is provided above the table 3, and its diamond scriber 6 is dropped onto the aluminum foil 4 at a position away from the wafer 1 on the rear end side of the wafer 1, and then The wafer 1 is then swept forward, passing over the wafer 1.

Then, a scribing scratch 7 for a cleavage starting point is formed only on the front edge of the wafer exposed from the front edge of the aluminum foil 4.

The above operation is repeated every time the table 3 is fed at a fixed pitch, resulting in a large number of scratches 7 on the front edge of the wafer 1 at a fixed pitch.
is formed, and this wafer 1 is pasted onto an adhesive sheet 8 made of extensible soft plastic such as vinyl and having an adhesive surface A on one side so that the scribing scratches 7 are exposed.

(2) Cleavage process (see FIG. 4) Next, the adhesive sheet 8 is fed and passed between the large-diameter rubber roller 9 and the hard small-diameter roller 10 opposing it, with the wafer 1 facing the rubber roller 9 side.

Then, the wafer 1 is pressed against the rubber roller 9 side at the action part of the small-diameter roller 10 and is bent, and cleavage progresses starting from each scribing scratch 7, and a large number of wafer pieces 11 are pasted in parallel on the lower surface of the adhesive sheet 8. It comes out from between the rollers in a state where it is covered.

■ Shredding line forming process (see Figure 5) The adhesive sheet 8 on which 11 groups of wafer pieces are pasted 17 in parallel as described above is held by suction on a movable table 16 that is fed intermittently, and a diamond scriber 17 cuts the pieces 1 into pieces.
On the upper surface of the first group, scribing scratches 18 are formed as shredding lines at a constant pitch in the longitudinal direction of the small pieces.

■ Shredding process The 11 groups of wafer pieces on which the 18 groups of shredding lines have been formed are shredded along each shredding line 18 using a pressing means similar to the roller-type cracking means shown in FIG. chip 1
Nine groups are obtained.

■ Chip separation process (see Fig. 6) The adhesive sheet 8 to which the group of chips 19 is attached is placed in the lifter 21 with its edge being clamped and fixed by the chuck 20.
After being appropriately heated by the heater 22 below the lifter, the sheet 8 is greatly expanded by the lifter 21 rising, and the attached chips 19 are separated at appropriate intervals.

If this sheet stretching process is carried out separately or simultaneously in the front-back and left-right directions, groups of 19 chips separated vertically and horizontally can be obtained as shown in FIG.

■ Antioxidant film coating process (see Figure 8) Next, the adhesive sheet 8 with the chip 19 group separated and pasted is introduced into a low temperature vapor phase growth device or sputtering device, and the sheet 8
and 813N4, Sl, Si under relatively low temperature conditions that do not adversely affect the previously coated positive resist 14.
An antioxidant coating 15 such as O2 or A], 203 is coated over the entire exposed surface of each chip.

(2) Protective film removal step Next, the positive resist 14 is dissolved and removed using an alkaline solution, for example, a 10% NaO nail, and the upper layer of the anti-oxidation film is also removed, followed by thorough washing with water and drying. by this,
As shown in FIG. 9, a chip 19 is obtained in which the antioxidant coating 15 is left not only on the cleavage surface S but also on both side surfaces T.

Incidentally, after checking the characteristics of the chip 19 obtained as described above, the chip 19 is transferred to the assembly process while being attached to the plate 8.

〔effect〕

As explained above, according to the method of the present invention, each wafer can be cleaved, shredded, coated with an antioxidant film, and separated into chips using an adhesive sheet, which greatly improves productivity. It became possible to do so.

In particular, according to the present invention, since the antioxidant coating is applied not only to the cleavage surface but also to the side surfaces of the chip at the same time, the side surface coating covers the PN junction even when the chip surface is fused and connected to a heat tank or the like. It acted as an insulating material to prevent short circuits, improving assembly yield and performance reliability.

[Brief explanation of drawings]

FIG. 1 is a perspective view of the cleavage pretreatment means in the method of the present invention, FIG. 2 is a side view thereof, FIG. 3 is a perspective view of a wafer that has been pretreated for cleavage, and FIG. 4 is a perspective view of the cleavage treatment means. A perspective view, FIG. 5 is a perspective view of the chopping wire forming element stage, FIG. 6 is a side view of the chip separation means, FIG. 7 is a perspective view showing chips after separation processing, and FIG. 8 is an antioxidant film coating treatment. FIG. 9 is an enlarged perspective view of a single completed chip, and FIG. 10 is an enlarged perspective view of a single chip obtained by the conventional method. 4. Aluminum foil, 7. Marking scratches, 8. Adhesive sheet, 19. Chip. Applicant: ROHM Co., Ltd. Agent: Kazuhide Okada, patent attorney

Claims (1)

[Claims] (1) The process of coating the surface of the raw wafer with an alkali-soluble positive resist on which the scribe scratches for cleavage starting points are to be formed, and the wafer pasted on the adhesive sheet with the surface where the scribe scratches are formed exposed. A process of cleaving the wafer by applying pressure from the outer surface of the sheet, a process of cutting each wafer piece on the adhesive sheet into pieces at a predetermined pitch in the longitudinal direction to form chip groups, and a process of stretching the adhesive sheet. A process of separating each chip from each other using a pressure-sensitive adhesive sheet, and applying SiO_4, Si, SiO_2, and Al to the entire exposed surface of the separated chip group on the adhesive sheet.
A method for manufacturing a semiconductor laser chip, which includes a step of coating with an antioxidant film such as _2O_3, and a step of dissolving and removing the positive resist of each chip with an alkali, followed by washing and drying.