JPH0212109A - Manufacture of optical integrated circuit - Google Patents

Abstract

PURPOSE:To enable highly-accurate chip segmenting which is superior in mass- productivity and yield by forming a cleavage flaw at a specific position of a wafer peripheral part by laser beam irradiation, then straining the entire surface of the wafer and advancing the cleavage at a time, and segmenting many circuit chips at the same time. CONSTITUTION:A wafer 41 is installed on a stage 49 with a fine adjusting mechanism and the specific position on the wafer periphery is irradiated with a laser beam 43 to specific length to make a flaw 44. Then the wafer 41 is detached from the stage 49 and sandwiched between two transparent cohesive films 54, whose peripheral parts are fixed hermetically to the opening part 56 of a box 55. Then air is admitted to the box 55 from an air intake 57 to increase the internal air pressure and then the films 54 expand owing to the air pressure difference to cleave along the flaw 53 at a time, thereby dividing chips 52 of individual circuits. Consequently, the highly-accurate chip segmenting which is superior in mass-productivity and yield is enabled.

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial Application> The present invention relates to an improvement in a method for cutting out a wafer on which a plurality of leading wave circuits are formed into respective optical waveguide circuit chips in the production of optical integrated circuits.

<Prior Art> FIGS. 3 and 4 show examples of the prior art of optical S product circuits. Third
The figure shows an integrated optical demultiplexing circuit for a wavelength division multiplexing transmission system by Takami et al. (National Conference of the Institute of Electronics and Communication Engineers, 1985, No. 1050), which is mounted on a thin optical waveguide film 11 formed on a silicon single crystal substrate. A collimation and condensing lens 13 and a transmission type diffraction grating 12 are formed on the substrate, and input/output fibers 14 and Is are provided at both ends 16 of the substrate. Figure 4 shows T, 5UHARA at, al (Appl,
Phys, Latt,, VOL.

40, magnetic 2. P, 120. (1982)) is an example in which a grating demultiplexer 22 and a photodiode 23 are integrated into a thin optical waveguide film 24 on a silicon substrate 21. In FIG. 4, 25 is an input fiber, and 26 is an end face of an optical waveguide film. These circuits are so-called hybrid optical integrated circuits, in which the basic element is an optical waveguide circuit formed on a silicon substrate, which is combined with light-receiving and emitting elements, fibers, and electronic circuits. −
A monolithic optical integrated circuit in which an optical waveguide circuit, a light receiving/emitting element, and an electronic circuit are collectively formed on a group V compound semiconductor substrate has also been reported. In any optical integrated circuit, a plurality of circuits are formed on a crystal substrate by photolithography, similar to LSI manufacturing technology, and then each circuit is cut out as a chip and used. When cutting out a chip, LSI requires only cutting with a peripheral blade, but in optical integrated circuits, in order to obtain good connection characteristics between the waveguide circuit and the fiber, the waveguide circuit end face 16. shown in FIGS. 3 and 4 is used. It is necessary to achieve a smoothness of 26 that is less than a fraction of the wavelength used. For this reason, in the conventional manufacturing of optical integrated circuits, when cutting chips, a method of optically polishing the end face of the waveguide circuit after cutting or a method of seeding along the orientation of the crystal substrate is adopted. .

<Problems to be Solved by the Invention> However, the former method of optically polishing the end face of the waveguide after cutting requires complicated cutting and polishing steps, takes a long time, and is prone to damage to the end face of the thin film waveguide. It was difficult to obtain a good yield. On the other hand, in the latter method of cutting the seeds along the orientation of the crystal substrate, the thin film waveguide is cut simultaneously with the crystal seeds, so that a good waveguide end face can be easily obtained.

Here, an example of the chip cutting process using the conventional gluing method is shown in FIG. 5. First, as shown in FIG. Alternatively, make an interspecies wound 34 in a part (thick line part), and then use a blade on the interspecies pot 34 as shown in the figure (
As shown in b), stress F is applied to separate the seeds into strips. Next, this strip-shaped substrate is scratched and stressed as shown in the same figure (cl), and finally a chip 32 is obtained as shown in the same figure (d). However, in this open method, , the number of times of scratching and applying stress was high (and the working conditions were complex, making it difficult to increase mass productivity and yield.
It was also difficult to accurately make scratches on the order of microns at predetermined positions.

The purpose of the present invention is to solve the above-mentioned drawbacks of the prior art and to achieve high accuracy in the production of optical integrated circuits, with respect to a die-cutting method for cutting out chips having optically good waveguide circuit end faces from a wafer. It also provides a chip cutting method that is superior in mass production and yield.

Means for Solving the Problems> The present invention aims at forming optical integrated circuits.When cutting out chips having optically good waveguide circuit end faces from a wafer, a YAG or CO2 laser beam, for example, is applied to a predetermined position on the periphery of the wafer. The wafer is irradiated over a predetermined length to accurately create minute scratches with a certain width and depth at that location, and then stress is applied to the entire surface of the wafer to concentrate stress on the scratches. This method involves cutting out multiple chips at once along the wound. Therefore, the present invention differs from the prior art in that it is possible to cut out chips with high precision and excellent mass productivity and yield by simple means of making scratches with a laser beam and applying stress overall.

Embodiment Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

An embodiment of the present invention is shown in FIGS. 1 and 2. FIG. FIG. 1 shows a method of making scratches on a wafer on which a plurality of optical integrated circuits are formed, and FIGS. 2(a) and 2(b) show a method of applying stress to the scratched wafer.

First, as shown in Fig. 1, a silicon substrate or
A wafer 41, which may be a group compound semiconductor substrate, is placed on a stage 49 with a fine movement mechanism, and a laser beam 43 is irradiated over a predetermined length at a predetermined position on the periphery of the urchin to create a scratch 44. The laser beam 43 is emitted by a laser light source 48, refracted by a mirror 47, converged by a lens 46, and irradiated onto the wafer. When making scratches, the stage 49 is moved so that the scratches 44 are parallel to the facets 45 that determine the orientation of the substrate crystal and are spaced at regular intervals, and the stage 49 is moved so that the scratches are perpendicular to the facets 45 and at regular intervals. move. The depth and width of the scratch can be arbitrarily adjusted by adjusting the output and aperture of the laser light source 48. If the stage 49 and the laser light source 48 are controlled by a computer, it is possible to speed up the incision work and reduce the power required. Once the wafer periphery has been scratched through the above steps, it is removed from the stage 49 and the wafer 51 is sandwiched between two transparent adhesive films 54 as shown in FIG. 2 (al(b)). The peripheral parts of these films 54 are hermetically fixed to the opening 56 of the box 55. After that, air is introduced into the box 55 from the air inlet 57 to increase the internal pressure. At the same time, the film 54 expands due to the pressure difference. Stress acts on the entire wafer 51 held between these.The stress acting on the wafer 51 here does not act uniformly, but concentrates on the scratches 53.For this reason, the wafer 51
1 is injected all at once along the scratch 53 and divided into chips 52 for individual circuits. In the figure, 59 is an interspecific surface. Thereafter, the film 54 is removed from the opening of the box 55, but in this state each chip 52 is held by the adhesive film 54 and aligned in the same manner as a wafer, making subsequent handling easier.

In this way, in the present invention, the interseating scratches are formed with high precision by laser beam irradiation, and stress is applied to the entire surface of the wafer to perform the interseating at once, so the cutting process of optical integrated circuit chips is much easier than with the conventional technology. In addition to improving performance and yield, there is no need to replace blades or diamond needles.

<Effects of the Invention> As described above in detail based on the embodiments, the present invention provides a method for cutting out circuit chips by cutting out circuit chips by cutting out a workpiece in which a plurality of optical integrated circuits are formed. This method involves forming a pruning pot at the position of the wafer by irradiating it with a laser beam, and then applying stress to the entire surface of the wafer to advance the seeds all at once, cutting out a large number of circuit chips at the same time.This method has the following effects: .

■ Laser beam power Since the beam size can be controlled arbitrarily, it is possible to easily set the incision conditions to accommodate changes in the thickness and size of the interfering substrate.

■ It is possible to increase the precision of the scratch location and the dimensions of the scratch.

■ Since the incision is made without contact, there is no wear on the blade or diamond needle (and the yield of cutting work can be improved).

■ Mass production of circuit chips becomes possible because all types are processed at once.

■ By sandwiching the wafer between adhesive films and applying stress, the separated circuit chips are held in an aligned state, making subsequent handling easier.

[Brief explanation of the drawing]

1 and 2 show one embodiment of the present invention, and FIG. 1 is a perspective view for explaining a pot holder for seeds, and FIG. 2 (a
l (bl is a perspective view and a cross-sectional view showing the stress applying method, respectively, FIGS. 3 and 4 are explanatory diagrams of conventional technology related to optical integrated circuits, and FIGS. 5(a) to (dl are respectively illustrations of conventional optical integrated circuits) It is a process diagram showing a circuit chip cutting method in a circuit manufacturing process. In the drawing, 11 is a thin optical waveguide film, 12 is a transmission type diffraction grating, 13 is a lens, 14 is an input fiber, 15 is an output fiber, and 16 is a guide. Wave film end face, 21 is a silicon substrate, 22 is a grating splitter, 23 is a photodiode, 24 is a thin film optical waveguide film, 25 is an input fiber, 26 is a wave guide film end face, 31 is a wafer, 32 is a chip, 33 is a 44 is a diamond needle, 34 is a pan for interfolds, 35 is a facet, 41 is a wafer, 42 is a chip, 43 is a laser beam 44 is a scratch, 45 is a facet, 46 is a lens, 47 is a mirror 48 is a laser light source, 49 is a stage, 51 is a wafer, 52 is a chip, 53 is a scratch, 54 is an adhesive film, 55 is a box, 56 is an opening, 57 is an air inlet, 58 is an air outlet, and 59 is an interspecies surface.

Claims (2)

[Claims] (1) In manufacturing optical integrated circuits whose basic elements are optical waveguide circuits formed on silicon substrates or III-V group compound semiconductor substrates, the wafer, which is a crystalline substrate on which multiple optical waveguide circuits are formed, is separated into individual wafers. When cutting out chips for optical waveguide circuits, a plurality of scratches are formed at predetermined positions around the wafer using a laser beam, and then stress is applied to the entire wafer to concentrate the stress on the scratches. A method for manufacturing an optical integrated circuit, comprising cleaving the wafer all at once along the scratches and dividing the wafer into a plurality of chips. (2) In claim 1, the wafer in which the scratches have been formed is sandwiched between two adhesive films, and the periphery of the adhesive film is fixed, and air pressure is applied to the central part of the wafer. A method for manufacturing an optical integrated circuit, characterized in that stress is concentrated on the scratches on the wafer by applying a stress to the scratches on the wafer.