JP2002064236A - Cleaving method of crystalline substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a cleavage plane at a plurality of positions with a single cleavage. SOLUTION: A guide hole 104 of a triangular column is formed. In this case, the triangular column uses a triangle as a bottom surface, and the triangle is arranged so that a base crosses the cleavage plane 106 started from a vertex, where two adjacent sides of a guide groove 103 cross. Then, stress is applied to a position opposite to the guide groove formation section of a substrate 101 by a tool 105, and two cleavage planes 106 and 106a are formed at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaving a crystalline substrate used for manufacturing a semiconductor laser.

[0002]

2. Description of the Related Art In an optical device using a semiconductor substrate such as a semiconductor laser, a semiconductor optical amplifier, a semiconductor optical modulator, and an optical waveguide device, it has been proposed to use a cleavage plane as an optical input / output end face. As a method of manufacturing a cleavage plane that becomes an optical input / output end face, there is a method of forming a groove in a part of a substrate on which a predetermined semiconductor layer is laminated with a diamond scriber or the like and performing cleavage along the groove. A method has also been proposed in which a groove is formed in a part of the substrate by etching, and cleavage is performed using the groove as a guide groove.

In this cleaving method, as shown in FIG. 4, a substrate 401 made of a compound semiconductor on which elements such as an active layer 402 are formed is prepared. A groove 403 is formed at a position where a line on the surface and one end of the substrate 401 intersect. Next, a wedge-shaped jig 4 is formed on the back surface of the substrate 401 in the groove 403 forming portion.
05 and the jig 405
The substrate 401 is cleaved by applying a predetermined force in the direction.

[0004]

However, in the above-described conventional cleavage method, only one plane having a uniform crystal plane is formed as a cleavage plane formed by one cleavage operation. Therefore, for example, there is a problem that a plurality of elements having different element lengths in the optical path direction of the active layer 402 cannot be formed.

[0005] The present invention has been made to solve the above problems, and has as its object to allow cleavage planes to be formed at a plurality of positions by a single cleavage.

[0006]

According to the method for cleaving a crystalline substrate of the present invention, a first substrate extending from an end of a main surface of a crystalline substrate to a center of the substrate and having a first base overlapping the end is provided. When a guide groove of a triangular prism with a triangle as a bottom is formed and stress is applied to a position facing the guide groove forming portion on the back surface of the substrate,
A guide hole of a triangular prism having a bottom surface of a second triangle disposed so that a second bottom side intersects a first cleavage plane starting from a first vertex at which two first adjacent sides of a first triangle of the guide groove intersect. Then, a stress is applied to a position facing the guide groove forming portion on the back surface of the substrate, and the first cleavage surface and the second cleavage surface starting from the second vertex where two second adjacent sides of the second triangle intersect with each other. It is intended to cleave the substrate. According to the present invention, the tip of the triangular prism guide groove on the substrate center side is the starting point of cleavage that forms the first cleavage plane, and the tip of the triangular prism guide hole is
This is the starting point of cleavage that forms the second cleavage plane. The second
If the vertices are arranged other than on the extension of the first cleavage plane, the first cleavage plane and the second cleavage plane are formed at different positions.

In the above invention, an additional guide hole of a triangular prism having a bottom surface of a third triangle disposed so that the third base crosses the second cleavage surface is newly formed, and the first cleavage surface and the second cleavage surface are formed.
The substrate may be cleaved at a cleavage plane and a third cleavage plane starting from a third vertex at which two third adjacent sides of the third triangle intersect.
In the present invention, if the third vertex is arranged other than on the extension of the second cleavage plane, the second cleavage plane and the third cleavage plane are formed at different positions. Further, the guide groove and the guide hole may be formed by selective etching.

[0008]

Embodiments of the present invention will be described below with reference to the drawings. <First Embodiment> FIG. 1 is a perspective view (a) and a cross-sectional view (b) illustrating a cleavage method according to an embodiment of the present invention.
It is. In the first embodiment, as shown in FIG. 1A, after forming an element such as an active region 102 on a crystalline substrate 101 made of, for example, n-type InP, a triangular prism (triangular prism) in plan view is formed. A guide groove 103 and a guide hole 104 are formed, and a blade portion of a wedge-shaped jig 105 is applied to the back surface of the substrate 101 where the guide groove 103 is formed, and a predetermined force is applied from the upper portion of the substrate 101 toward the jig 105. By forming two cleavage planes 106 and 106a on the substrate 101 at the same time,
01 is to be cleaved. In FIG. 1, the main surface of the substrate 101 is 100 surfaces.

[0009] The active region 102, as shown in FIG. 1 (b), n formed on the substrate 101 ^- and the lower cladding layer 121 made of InP in the form, the band gap wavelength of InGaAsP of 1.5μm Active layer 122,
p ^- becomes the upper clad layer 123 consisting of the shape of InP, are filled with the buried layer 124 surroundings become semi-insulating InP. Lower cladding layer 121, active layer 12
2. For the upper cladding layer 123, a compound semiconductor constituting each layer is crystal-grown on the substrate 101 by metal organic chemical vapor deposition, and these are selectively etched by dry etching using a hydrocarbon-based etching gas. Can be formed.

Here, the guide groove 103 and the guide hole 104
Will be described. First, the guide groove 103 is, for example,
It is a triangular prism whose base is an isosceles triangle having a base (first base) at a side (end) of the substrate 101 parallel to the active region 102 formed in a stripe shape. Note that the triangle (first triangle) on the bottom surface of the triangular prism does not need to be an isosceles triangle, and two adjacent sides may have different lengths. In addition, for the triangle on the bottom surface of the guide groove 103, for example, the extension direction on the vertex (first vertex) side of a line connecting the midpoint and the vertex of the base of the triangle may be the cleavage direction. When the bottom surface of the triangular prism is an isosceles triangle, the substrate 101 made of InP is used.
The cleavage direction of the active region 10 is a stripe.
2 is perpendicular to the side (end) of the substrate 101 parallel to 2.

On the other hand, the guide hole 104 is
Is a triangular prism whose base is an isosceles triangle (second triangle) having a base (second base) substantially parallel to the base of the triangle on the bottom surface of (3). In other words, the guide hole 104 is formed in the guide groove 10.
The bottom surface of the triangular prism is an isosceles triangle (second triangle) similar to the guide groove 103,
The base of the triangle on the bottom surface of the guide hole 104 and the base of the triangle on the bottom surface of the guide groove 103 have a substantially parallel relationship. The depth of the guide hole 104 is the same as that of the guide groove 103.
In the following, the base of the triangle on the bottom surface of the guide groove 103 or the guide hole 104 will be simply referred to as the bottom of the guide groove 103 or the guide hole 104.
Simply referred to as the top of the guide groove 103 or the guide hole 104

The guide hole 104 adjacent to the vertex from the bottom of the guide groove 103 is disposed so that the bottom of the guide hole 104 intersects a cleavage plane starting from the vertex of the guide groove 103. Further, the guide hole 104 adjacent to the specific guide hole 104 in the vertex direction from the bottom of the specific guide hole 104 is disposed such that the base of the adjacent guide hole 104 intersects a cleavage plane starting from the vertex of the specific guide hole 104. However, in the case of the substrate 101 made of InP of the present embodiment, since the main surface is 100,
A straight line connecting the midpoint and the vertex of the bottom of the guide groove 103 and the cleavage plane starting from the vertex of the guide groove 103 overlap. Similarly, a straight line connecting the midpoint and the vertex of the bottom of the guide hole 104 and a cleavage plane starting from the vertex of the guide hole 104 overlap.

The cleavage plane formed by the cleavage operation by the jig 105 is guided while connecting the parts where the stress is most strongly applied on the surface where the guide groove 103 is formed.
In the guide groove 103 of the triangular prism, stress concentrates along the side of the triangle (the intersection of the side and bottom of the groove) and the vertex of the triangle (2
The stress is highest at the upper end portion where two groove side surfaces intersect. As a result, the cleavage is made in the guide groove 103 of the triangular prism.
, And the cleavage plane 106 is induced from the vertex (first vertex) of the triangle.

The cleavage position (cleavage plane 106) induced at the vertex of the triangle advances on a line (first line segment) connecting the midpoint of the bottom of the guide groove 103 and the vertex, and the guide groove 103
From the bottom to the bottom of the adjacent guide hole 104 in the vertex direction. When the cleavage position reaches the bottom of the adjacent guide hole 104 in the vertex direction, in the adjacent guide hole 104,
As in the case of the guide groove 103, stress concentrates along the side (second side) of the triangle of the guide hole 104, and the stress concentrates most at the vertex of the triangle of the guide hole 104. As a result, the cleavage is guided along the side of the guide hole 104 adjacent to the triangle, and a new cleavage plane 1 is formed from the vertex of the guide hole 104.
06a is induced.

Here, from the line connecting the midpoint and the vertex of the bottom of the guide groove 103, that is, from the extension of the cleavage plane starting from the vertex of the guide groove 103, the vertex of the adjacent guide hole 104 in the vertex direction is determined. If the position is shifted, the guide groove 1
03 induced cleavage plane and adjacent guide hole 10
4 can be formed at different positions. Therefore, for example, the guide groove 103, a guide hole (first guide hole) 104 adjacent in the vertex direction of the guide groove 103, and another guide hole (second guide hole, not shown) adjacent in the vertex direction of the guide hole 104. ) Are arranged so as not to be on the same straight line, cleavage planes can be formed at three different positions.

Hereinafter, a cleavage method for forming a plurality of cleavage planes using a plurality of guide holes will be described. First, FIG.
As shown in (a), an active region 102 is formed on a substrate 101.
A plurality of double hetero-buried laser structures (semiconductor lasers) are embedded in the buried layer 124 and are formed at an interval of 400 μm from the end face 201 of the substrate 101. Next, a silicon oxide film having a thickness of about 0.2 μm is formed on the buried layer 124 of the substrate 101, and a resist pattern is formed thereon by a known photolithography technique. Figure 2 shows the resist pattern
The guide groove 103 and the guide holes 104a, 104 shown in FIG.
4b, 104c, the base length is about 7 μm
m, a plurality of isosceles triangular opening regions each having a length from the base to the vertex of 200 μm.

Opening regions for forming the guide grooves 103 are arranged such that the apexes are spaced at intervals of 300 μm (horizontal direction in FIG. 2), and the guide holes 104a and 104a are formed.
Opening regions for forming 4b and 104c were arranged such that the apexes were at 600 μm intervals. Also,
On the plane of the substrate 101, in the direction perpendicular to the end surface 201, the apex of the guide groove 103 and the apex of the guide hole 104a, the apex of the guide hole 104a and the apex of the guide hole 104b, the apex of the guide hole 104b and the apex of the guide hole 104c. And 400
Each opening area was arranged so as to have an interval of μm.

The guide hole 104a is shifted by 2 μm in a direction parallel to the end face 201 (right side in FIG. 2) from the guide groove 103 on the end face 201 side (lower side in FIG. 2) of the guide hole 104a. The guide hole 104b is
The guide hole 1 on the end face 201 side of the guide hole 104b
04a is shifted by 2 μm in a direction parallel to the end face 201. Similarly, the guide hole 104c is
c from the guide hole 104b on the end face 201 side, the end face 2
It is shifted by 2 μm in a direction parallel to 01. Therefore, for example, the guide hole 104c is 6 μm in a direction parallel to the end face 201 (right side in FIG. 2) from the guide groove 103 on the end face 201 side (lower side in FIG. 2) of the guide hole 104c.
It will be shifted.

Next, using the resist pattern as a mask, the underlying silicon oxide film is selectively etched by reactive ion etching using CF ₄ as an etching gas, and the opening region of the resist pattern is transferred to the silicon oxide film. To form an etching mask. Next, after the resist pattern is removed, the buried layer 124 and the substrate 101 are removed by about 3 nm by reactive ion etching using a halogen-based mixed gas using the etching mask.
Etching was performed to a depth of μm. Thereafter, the etching mask was removed, electrodes (not shown) were formed on the active region 102 by a lift-off method, and electrodes were formed on the back surface of the substrate.

As described above, as shown in FIG. 2A, the guide groove 103 and the guide holes 104a, 104b, 104c are respectively formed on the substrate 101 (embedded layer 124). As described above, the guide grooves 103 are arranged such that the respective apexes are located at intervals of 300 μm (see FIG. 2).
Guide holes 104a, 104b, 10
4c are arranged such that each vertex position is at an interval of 600 μm. In the direction perpendicular to the end surface 201 on the plane of the substrate 101, the apex of the guide groove 103 and the guide hole 10
4a, the top of the guide hole 104a and the guide hole 104
b, the top of the guide hole 104b and the guide hole 104c
Are arranged at an interval of 400 μm.

Thereafter, the jig 1 shown in FIG. 1A is provided on the back surface of the substrate 101 on the end face 201 where the guide groove 103 is formed.
The substrate 101 is cleaved by applying a blade portion 05 and applying a stress from the back surface of the substrate 101. In this cleavage, first, the cleavage is performed from the vertex position of the guide groove 103, and the cleavage surface 1 is formed.
06 is formed. The tip of the cleavage plane 106 reaches the bottom of the guide hole 104a, and the cleavage plane is the guide hole 104a.
And a new cleavage plane 106a is formed from the vertex of the guide hole 104a. Next, this cleavage plane 106a
Reaches the bottom of the guide hole 104b, the cleavage plane is guided to the side surface of the guide hole 104b, and a new cleavage plane 106b is formed from the vertex of the guide hole 104b. Next, the tip of the cleavage plane 106b reaches the bottom of the guide hole 104c, and the cleavage plane is guided to the side surface of the guide hole 104c to form a new cleavage plane 106c from the vertex of the guide hole 104c.

In the cleavage at the guide groove 103 having no guide holes 104a, 104b, and 104c in a direction perpendicular to the end face 201, the cleavage surface 107 induced from the apex of the guide groove 103 is separated from the other guide holes 104a, 104b, and 104. 1
It reaches the opposite end face without crossing 04c.
As described above, the laser array bar shape formed by cleavage has an element length of 306 μm, 304 μm, 30 μm, or 30 μm.
2 μm, 300 μm, 298 μm, 296 μm, 294
There will be multiple types of μm.

For example, in a laser array bar shape formed in the region 211, the element length is 300 μm. Also,
In the laser array bar shape formed in the region 212, the element length is 298 μm. In the laser array bar shape formed in the region 213, the element length is 296 μm. In the laser array bar shape formed in the region 214, the element length is 294 μm. Further, in the laser array bar shape formed on the right side of the area 214 in FIG.
06 μm. In the laser array bar shape formed on the right side of the region 213 in FIG. 2, the element length is 304 μm. In the laser array bar shape formed on the right side of the area 212 in FIG. 2, the element length is 302 μm. Area 21
1, the element length is 30 μm in the laser array bar shape formed on the right side of FIG.

As described above, according to the cleavage method of the present embodiment, a plurality of elements having different element lengths can be simultaneously formed. In the cleavage method of the present embodiment, when the element length of each formed element was measured, it was within ± 1 μm with respect to the design value. As described above, according to the present embodiment, cleavage can be performed with positional accuracy within ± 1 μm.

In the above description, as shown in FIGS.
The case where the bottom of the guide hole 104 is parallel to the end face 201 of the substrate 101 and the line segment indicating the direction in which the cleavage plane proceeds is orthogonal to the end face 201 and the bottom of the guide hole 104 is shown. Not something. For example, as shown in FIG. 3, on the crystalline substrate 101, guide holes 304a and 304b of triangular prisms having a triangular base whose bottom is not parallel to the end face 201 are formed together with the guide grooves 103, and cleavage is performed. Is also good.

In this case, for example, the guide hole 304a
Although the bottom side is arranged so as to intersect with the line segment formed by the cleavage plane 106 from the guide groove 103, it is not perpendicular. Similarly, the bottom of the guide hole 304b is the guide hole 3b.
Although they are arranged so as to intersect with the line segment of the cleavage plane 306a from the substrate 04a, they are not in a vertical relationship. Thus, the base of the triangle forming the guide hole is the guide groove 1
It is not necessary to be orthogonal to the cleavage plane starting from the vertex of 03. On the cleavage plane starting from the vertex of the guide groove 103,
What is necessary is just to arrange so that the bottom sides of guide holes may cross.
Further, in the above description, the case of forming a semiconductor laser using InP as a substrate has been described as an example, but the present invention is not limited to this. For example, cleavage for forming an emission end face of a semiconductor laser using GaAs as a substrate is described. Needless to say, it can be applied to

[0027]

As described above, according to the present invention,
Since the position of the cleavage plane formed from the end face of the substrate having crystallinity can be changed in the middle of the substrate, an excellent effect that cleavage planes can be formed at a plurality of positions by a single cleavage can be obtained.

[Brief description of the drawings]

FIG. 1 is a perspective view (a) and a cross-sectional view (b) illustrating a cleavage method according to an embodiment of the present invention.

FIG. 2 is a process chart for explaining a cleavage method according to the embodiment of the present invention.

FIG. 3 is a plan view for explaining a cleavage method according to another embodiment of the present invention.

FIG. 4 is a perspective view for explaining a conventional cleavage method.

[Explanation of symbols]

101: substrate, 102: active area, 103: guide groove,
104, 104a, 104b, 104c ... guide holes, 1
05 ... jig, 106, 106a, 106b, 106c,
107: cleavage plane, 121: lower cladding layer, 122: active layer, 123: upper cladding layer, 124: buried layer,
201 ... end face, 211, 212, 213, 214 ... area.

Claims (5)

[Claims] 1. A guide groove of a triangular prism extending from an end of a main surface of a substrate having crystallinity to the center of the substrate, and having a first triangle whose bottom surface is a first triangle overlapping the end, is formed. A first cleavage plane starting from a first vertex where two first adjacent sides of the first triangle of the guide groove intersect when a stress is applied to a position of the back surface of the substrate facing the guide groove forming portion; Forming a guide hole of a triangular prism having a second triangle as a bottom surface so as to intersect the second base, applying a stress to a position on the back surface of the substrate facing the guide groove forming portion, and applying a stress to the first cleavage surface Cleaving the substrate at a second cleavage plane starting from a second vertex at which two second adjacent sides of the second triangle intersect with each other. 2. The method for cleaving a crystalline substrate according to claim 1, wherein said second apex is arranged other than on an extension of said first cleavage plane. 3. The method for cleaving a crystalline substrate according to claim 1, wherein an additional guide hole of a triangular prism having a bottom surface of a third triangle disposed so that a third base crosses the second cleavage surface is formed. And a third starting from a third vertex at which the first cleavage plane, the second cleavage plane, and two third adjacent sides of the third triangle intersect.
A method for cleaving a crystalline substrate, comprising cleaving the substrate with a cleavage plane. 4. The method for cleaving a crystalline substrate according to claim 3, wherein the third apex is arranged other than on an extension of the second cleavage plane. 5. The method for cleaving a crystalline substrate according to claim 1, wherein the guide groove and the guide hole are formed by selective etching. Cleavage method.