JPS61203692A - Manufacture of semiconductor laser device - Google Patents

Abstract

PURPOSE:To reflect the laser beam emitted from a semiconductor laser element by using inclined planes without deforming a distribution of luminous intensity of the beam by forming a minute groove on a surface of a semiconductor substrate and effecting the anisotropic etching of the surface of semiconductor substrate, while masking one side so as to form V-shaped inclined planes and the low laser element connecting plane. CONSTITUTION:An opening 3 of slit form is formed on a surface of an N-type semiconductor substrate 1 and a minute groove 4 is formed by etching. On one side of the groove 4. A photoresist film 5 (mask) remains and anisotropic etching is done to form the first inclined plane 6 by utilizing the difference in etching rate due to a difference in directions of crystals. A V-shaped groove 7 is formed at the lower end of the inclined plane 6 and the laser element connecting plane 9 extending from the upper end of the second inclined plane 8 to the surface of substrate 1 is formed. A P-I-N type photodiode 10, a solder layer 14 for bonding of a semiconductor laser element are formed and a semiconductor laser element 15 is bonded so that the laser beam emitting side 16 of it faces the inclined plane 6.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a method for manufacturing a semiconductor laser device, and particularly a method for manufacturing a semiconductor laser device, in particular a method for fixing a semiconductor laser device on a semiconductor substrate and irradiating a part of the semiconductor laser device with a laser beam from the semiconductor laser device. The present invention relates to a method for manufacturing a semiconductor laser device in which an inclined surface for reflecting a laser beam is formed so that the direction of the laser beam is bent approximately 90 degrees and the laser beam is irradiated perpendicularly to a semiconductor substrate. An object of the present invention is to provide a new manufacturing method by which a semiconductor laser device can be easily obtained without the problem of the laser beam being reflected on a laser element connection surface to which a semiconductor laser element is fixed and causing the luminous intensity distribution of the laser beam to be distorted. It is.

BACKGROUND ART A semiconductor laser device is constructed by bonding a semiconductor laser element onto a part of a semiconductor substrate on which a photodiode for monitoring is formed, as shown in FIG. A low laser element connection surface C that connects to the lower end of the semiconductor laser element is formed by anisotropic etching that takes advantage of the fact that the etching speed differs depending on the crystal orientation of the semiconductor, and the semiconductor laser element d is fixed on the laser element connection surface C. However, there is one in which the laser beam emitted from the semiconductor laser element d is reflected by an inclined surface and emitted perpendicularly to the surface of the semiconductor substrate 3. e is the semiconductor substrate 3 on the opposite inclined surface side of the semiconductor laser element d.
This is a photodiode formed on the surface.

The manufacturing method of such a semiconductor laser device is such that the laser beam emitted from the active layer f of the semiconductor laser element d is
The light can be reflected by an inclined surface having an inclination angle of @ and can be emitted in a direction perpendicular to the surface of the semiconductor substrate a. Therefore, there is an advantage that the laser beam can be emitted perpendicularly to the stem surface simply by pellet-ponding the semiconductor substrate a onto the stem surface.

Problems to be Solved by the Invention By the way, the method for manufacturing such a semiconductor laser device is as follows:
If the laser beam emitting end face g of the semiconductor laser element d is located on the boundary between the inclined surface and the laser element connection surface C, that is, if the semiconductor laser element d is placed as close to the inclined surface as possible, the semiconductor laser Since the active layer f of the laser element d is only slightly higher than the laser element connection surface C, a part of the light emitted from the active layer f, especially the light emitted obliquely downward, is reflected by the inclined surface. In this case, the laser beam emitting end face g of the semiconductor laser element d is irradiated, and the luminous intensity distribution of the laser beam emitted from the semiconductor laser device becomes distorted. In addition, when the semiconductor laser element d is fixed at an appropriate distance from the boundary between the inclined surface and the laser element connection surface C as shown in FIG. 3, the laser beam emitted diagonally downward from the active layer f is The light is reflected on the element connection surface C, resulting in a phenomenon in which a good luminous intensity distribution cannot be obtained (this phenomenon is called vignetting).

The present invention was made to solve such problems,
This is a novel technology that allows the semiconductor laser element to be sufficiently separated from the inclined surface that reflects the laser beam from it, eliminates vignetting, and reflects the laser beam emitted from the semiconductor laser element so that the luminous intensity distribution does not become uneven. The present invention attempts to provide a method for manufacturing a semiconductor laser device.

Means for Solving the Problems A first method for manufacturing a semiconductor laser device of the present invention to solve the above problems is to form a microgroove on the surface of a semiconductor substrate, and mask one side of the microgroove. By anisotropically etching the surface of the semiconductor substrate, a V-shaped sloped surface at the lower end and a low laser element connection surface connected to the sloped surface via the V-shaped groove are formed. The semiconductor laser element is fixed onto the laser element connection surface.

A second aspect of the present invention for solving the above problems is to form a V-shaped groove consisting of two slopes, a first and a second slope, by anisotropic etching, and to A flat laser element that extends in a direction away from the first inclined surface from the etched upper end of the second inclined surface by etching the surface of the semiconductor substrate to a depth shallower than the V-shaped groove with the surface masked. A connecting surface is formed, and a semiconductor laser element is fixed onto the laser element connecting surface.

Effect: According to the method of manufacturing a semiconductor laser device of the present invention, the first one forming the reflecting surface, whether it is the first one or the second one,
A ■-shaped groove is interposed between the inclined surface of the laser device and the laser element connecting surface on which the semiconductor laser element is bonded, and therefore, the laser element connecting surface can be separated from the laser beam reflecting inclined surface while eliminating vignetting. can be released. Therefore, the laser beam emitted from the semiconductor laser element can be reflected by the inclined surface without distorting its luminous intensity distribution.

EXAMPLES Below, a method for manufacturing a semiconductor laser device of the present invention will be explained in detail according to examples shown in the accompanying drawings.

FIGS. 1A to 1E show an example of the method for manufacturing a semiconductor laser device of the present invention in the order of steps.

(A) A photoresist film 2 is formed on the surface of an N-type semiconductor substrate 1 made of silicon, and the photoresist film 2 is exposed to light.
By development, a slit-shaped opening 3 having a minute width is formed. Then, by etching the surface of the semiconductor substrate 1 using the photoresist film 2 as a mask, microscopic
form.

FIG. 1(A) shows the state after the microgrooves 4 have been formed. Note that the microgrooves 4 may be formed by a mechanical method using a cutting saw or the like instead of photoetching.

(B) The photoresist film 2 on the surface of the semiconductor substrate 1 is removed, and a new photoresist film 5 is formed. Then, although the photoresist film 5 is left on one side of the microgroove 4, the photoresist film 5 is removed at least on the other side of the microgroove 4 by exposure and development. Figure 1 (B
) indicates the state after development processing.

(C) Anisotropic etching is performed using the photoresist film 5 as a mask. This anisotropic etching is performed by wet etching, which takes advantage of the fact that the etching speed differs depending on the crystal orientation of the silicon semiconductor (l l 1).
The etching is performed so that the first inclined surface 6 of the surface is formed, and the depth of the etching is made appropriately shallower than the V-shaped groove 7. This anisotropic etching progresses from the micro groove 4 as a starting point, and the inclined surface 6
The lower end of the V-shaped groove 7 has a depth similar to that of the micrometer 4.
is formed. One slope of the V-shaped groove 7 is the lower end of the first slope 6, and 8 is a second slope forming the other slope of the V-shaped groove 7.

By this etching, the inclined surface 6 and the V-shaped groove 7 are formed.
In addition, a laser element connection surface 9 is formed extending from the upper end of the second inclined surface 8 in parallel to the surface of the substrate 1. FIG. 1(C) shows the state after the etching is completed.

(D) A PIN type photodiode 10 is formed in a region appropriately spaced from the V-shaped groove 8 on the laser element connection surface 9.

Reference numeral 11 designates an N-type semiconductor region forming a substantial intrinsic region (I) of the PIN-type photodiode IO, and reference numeral 12 designates a P-type semiconductor region selectively formed on the surface of the semiconductor region 11. The surface of the diode 10 is covered with an insulating film (Si0
2) Covered by 13.

Next, the photodiode 10 on the laser element connection surface 9 is
A solder layer 14 for bonding the semiconductor laser device is formed on the region between the forming portion and the second inclined surface 8. Figure 1 (
D) shows the state after the solder layer 14 is formed.

(E) After that, the semiconductor laser element 1 is placed on the solder layer 14.
5 is bonded so that its laser beam emitting end surface 16 faces the first inclined surface 6 side.

Therefore, the end surface opposite to the laser beam emitting end surface 16, that is, the monitoring laser beam emitting end surface 17 faces the photodiode 10 side, and 18 is the active layer of the semiconductor laser element 15. FIG. 1(E) shows the state after the bonding. After that, mounting such as beretarization and bonding to the stem is performed.

According to this method of manufacturing a semiconductor laser device, a V-shaped groove 7 is formed between the inclined surface 6 and the low flat laser element connecting surface 9.
separated by. Therefore, part of the laser beam emitted from the active layer 18 of the semiconductor laser device 15,
In particular, the user is no longer accustomed to the fact that the laser beam emitted diagonally downward is reflected by the inclined surface 6, enters the laser beam emitting end face 16, and is re-reflected there, and vignetting, that is, the laser beam from the semiconductor laser element 15. First, it is possible to avoid the phenomenon in which the semiconductor laser element is reflected on the bonded flat surface, resulting in a deviation in the luminous intensity distribution.

FIGS. 2A to 2F show another embodiment of the method for manufacturing a semiconductor laser device of the present invention in the order of steps.

(A) A photoresist film 2 is formed on the surface of a semiconductor substrate 1, and a slit-shaped opening 3 is formed in the photoresist film 2 by exposure and development. FIG. 2(A) shows the state after the opening 3 is formed.

(B) Anisotropic etching is applied to the surface of the semiconductor substrate 1 using the photoresist film 2 as a mask. Etching is performed so that inclined surfaces 6 and 8 of the (111) plane are formed. Reference numeral 7 designates a ■-shaped groove consisting of the inclined surfaces 6 and 8. FIG. 2(B) shows the state after the V-shaped groove 7 is formed.

(C) After that, the photoresist film 2 is removed and a photoresist film 5 is applied again. The photoresist film 5 is left on one side from the lower end of the V-shaped groove 7, but the photoresist film 5 on the other side is removed by exposure and development.

The other inclined surface 8 and a region on the opposite side of the inclined surface 6 from the inclined surface 8 are exposed. FIG. 2(C) shows the state after the development process is completed.

(D) Using the photoresist film 5 as a mask, the surface portion of the semiconductor substrate 1 is etched. The depth of this etching is appropriately shallower than the depth of the V-shaped groove 7. As a result, the height of the inclined surface 8 becomes lower than the surface of the semiconductor substrate l, and a laser element connection surface extends from the lowered upper end of the inclined surface 8 toward the side opposite to the inclined surface 6 in parallel with the surface of the semiconductor substrate l. 9 will be formed. FIG. 2(D)' shows the state after the etching is completed.

Thereafter, as shown in FIG. 2(E), a PIN type photodiode 10 and a solder layer 14 for bonding the semiconductor laser device are formed, and then, as shown in FIG. This figure 2 (
The steps shown in E) and (F) are the same as the steps shown in FIGS. 1(D) and (E), and detailed explanation thereof will be omitted.

This method of manufacturing a semiconductor laser device also allows the first
The semiconductor laser device 1 is manufactured in exactly the same way as the manufacturing method shown in the figure.
A ■-shaped groove 8 can be interposed between the inclined surface 6 that reflects the laser beam from the semiconductor laser device 5 and the laser device connection surface 9 to which the semiconductor laser device 15 is bonded. Therefore, it is possible to obtain a semiconductor laser device that can avoid problems such as vignetting.

In the above embodiment, a metal film may be formed on the inclined surface 6 that reflects the laser beam in order to improve specular reflection.

Effects of the Invention As described above, according to the method for manufacturing a semiconductor laser device of the present invention, one inclined surface and a semiconductor laser element are bonded, regardless of whether it is the first or second one. A V-shaped groove is interposed between the laser element connecting surface and the laser element connecting surface, so that the laser element connecting portion can be separated from the laser beam reflecting slope, that is, the first slope while eliminating vignetting. . Therefore, the laser beam emitted from the semiconductor laser element can be reflected by the inclined surface without distorting its luminous intensity distribution.

[Brief explanation of the drawing]

1(A) to 1(E) are cross-sectional views showing an example of the method for manufacturing a semiconductor laser device of the present invention in the order of steps, and FIG. 2(A)
) to (F) are cross-sectional views showing another embodiment of the method for manufacturing a semiconductor laser device according to the present invention in the order of steps, and FIG. 3 is a cross-sectional view of the semiconductor laser device for explaining the background art. Explanation of symbols 1s: Semiconductor substrate, 4: Micro groove, 5: Φ mask, 68: First inclined surface, 7: Φ-V-shaped groove,
8. O. Second inclined surface, 9... Laser element connection surface. 15... Semiconductor laser element. 16... Laser beam emission end face Fig. 2

Claims (2)

[Claims] (1) Forming a microgroove on the surface of a semiconductor substrate, masking one side of the microgroove on the surface of the semiconductor substrate, and performing an anisotropic etching process using the difference in etching speed due to the difference in crystal orientation in this state. a first inclined surface and a second inclined surface that extends diagonally upward from the lower end of the inclined surface and forms a V-shaped groove between the lower end of the inclined surface; A laser element connecting surface extending in a direction away from the first inclined surface from the upper end of the second inclined surface and lower than the upper end of the first inclined surface is formed at the same time, and then a first connecting surface of the laser element connecting surface is formed. A method for manufacturing a semiconductor laser device, comprising: fixing a semiconductor laser element on a portion on the slope side so that its laser beam emitting end face faces the first slope side. (2) The surface of the semiconductor substrate is selectively covered with a mask so that slit-like uncovered areas are created, and in this state an anisotropic etching process is applied to the semiconductor substrate surface that takes advantage of the difference in etching speed due to the difference in crystal orientation. A V-shaped groove consisting of two sloped surfaces, a first and a second, is formed by applying it to the surface of the semiconductor substrate.Then, the first sloped surface of the V-shaped groove is masked, and the surface portion of the semiconductor substrate is exposed in this state. By etching to a depth shallower than the depth of the V-shaped groove, a laser cord connecting surface is formed that extends from the upper end of the second inclined surface of the V-shaped groove, which is lowered by the etching, in a direction away from the first inclined surface. and then, a semiconductor laser device is fixed on a portion of the laser device connecting surface on the first slope side so that the laser beam emitting end face thereof faces the first slope side. manufacturing method