JPH11103135A - Board for gallium nitride crystal growth, and its application - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a substrate for GaN crystal growth with which a high quality GaN substrate which is thick and moreover does not contain defects such as a transposition, etc., can be obtained, and the manufacture of a GaN semiconductor element using it. SOLUTION: A mask region 12 covered with a mask layer 2 and nonmask region 11, where the base substrate face is exposed, are made at the face of a base substrate 1. A material where crystals will not grow substantially from its own surface is used for the mask layer. In the case of making the upper part of the mask region into low transposition, the mask region is made in such form that at least the outline includes two straight parallel lines y1 and y2 which extend in the direction <1-100>. Furthermore, a width w1 of two parallel straight lines is made smaller than the width of a GaN semiconductor element, and moreover is made larger than the width of the active part of the element. In this case for, dividing the GaN semiconductor element into separate pieces, it is preferable to make use of a nonmask region.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a substrate for growing a GaN-based crystal and a method for manufacturing a GaN-based semiconductor device using the same.

[0002]

2. Description of the Related Art A general GaN-based semiconductor crystal (hereinafter referred to as G
As a method of growing a thick film of an aN-based crystal, a buffer layer such as ZnO is formed on a sapphire substrate, and a hydride vapor phase epitaxial growth method (hereinafter, referred to as “HVP”) is formed thereon.
E ") for growing a GaN-based crystal. Also,
As an improvement technique, a substrate such as spinel, LGO, LAO, ZnO, SiC, or the like is used instead of a sapphire substrate, an easily cleavable substrate is used, or a method of selectively growing a mask on the substrate surface is used. There is.

[0003]

SUMMARY OF THE INVENTION However, GaN
When a system crystal is grown in a thick film, a large stress is applied to an interface due to a difference in a lattice constant and a thermal expansion coefficient between a sapphire crystal and a GaN system crystal, so that a GaN crystal layer is broken and a large substrate cannot be obtained. There was a point. In addition, large dislocation density (about 1 × 10 ⁹ cm ⁻² to 1 × 10 ¹⁰ cm ⁻² )
However, there is a problem that only the GaN-based crystal substrate can be obtained. Here, dislocations are defects that occur when a semiconductor layer is grown on a substrate in a state where lattice constants do not match (lattice mismatch), and these dislocations are crystal defects. Work as a non-radiative recombination center,
When the GaN semiconductor material is used for a light-emitting element, the light-emitting characteristics and the life characteristics are deteriorated.

[0004] The present invention provides a GaN-based crystal growth substrate capable of efficiently obtaining a high-quality GaN-based substrate that is thick and does not include defects such as dislocations, and a Ga-based substrate using the same.
An object of the present invention is to provide a method for manufacturing an N-based semiconductor device.

[0005]

SUMMARY OF THE INVENTION The present invention has the following features. (1) A GaN-based crystal growth substrate used for manufacturing a GaN-based crystal substrate constituting a GaN-based semiconductor element. G
A mask layer is provided on a part or all of the base substrate surface on which the aN-based crystal can be grown so as to form a mask region and a non-mask region. The mask layer is made of a material from which GaN-based crystals cannot substantially grow from its own surface. The formation pattern of the mask layer is such that when a GaN-based crystal is grown up to cover the upper surface of the mask layer with the non-mask region as a starting point of growth, the width of the low dislocation portion in the crystal is the GaN-based semiconductor. This is a pattern formed so as to be larger than the width of the active portion in the device.

For example, the mask region includes two parallel straight lines extending in the <1-100> direction of the GaN-based crystal grown on the base substrate in the outline, and the width of the two parallel straight lines is determined by the GaN-based crystal. It is assumed that the width is equal to or smaller than the width of the semiconductor element and equal to or larger than the width of the active portion of the element. Alternatively, the non-mask region includes two parallel straight lines extending in the <11-20> direction of the GaN-based crystal grown on the base substrate in the outline, and the width of the two parallel straight lines is equal to the width of the GaN-based semiconductor device. And not less than the width of the active portion of the element.

(2) The mask region is a band-like region determined by the two parallel straight lines, and a plurality of the mask regions are formed at regular intervals so as to form parallel stripes. Alternatively, the non-mask region is the parallel 2
It is a band-like region determined by a straight line, and a plurality of band-like mask layers are formed at equal intervals so that this non-mask region becomes a parallel stripe.

(3) The GaN-based semiconductor device is a GaN-based stripe laser, the direction in which the two parallel straight lines extend is the longitudinal direction of the stripe portion in the stripe laser, and the width of the active portion is the width of the stripe portion. The GaN-based crystal growth substrate according to the above (1) or (2), wherein

(4) The GaN-based crystal growth substrate according to any one of (1) to (3), wherein the GaN-based semiconductor element is a GaN-based light-emitting diode.

[0010] (5) base substrate, at least the surface layer thereof is _{In X Ga Y Al Z N (} 0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0
≦ Z ≦ 1, X + Y + Z = 1), the substrate for growing a GaN-based crystal according to the above (1).

(6) Using the GaN-based crystal growth substrate according to any one of (1) to (5) above, and starting from a non-mask region on the substrate as a starting point and covering the mask layer over the GaN-based crystal layer. Growing a GaN-based crystal element such that an active portion of the GaN-based semiconductor element is formed in a portion of the GaN-based crystal layer where a low dislocation has occurred (for example, at least on a mask region in the GaN-based crystal layer). Growing a semiconductor layer to form a stacked body including a GaN-based semiconductor element;
Separating the stacked body into individual GaN-based semiconductor devices.

(7) The substrate for growing a GaN-based crystal is the substrate for growing a GaN-based crystal according to the above (3), wherein the dividing in the dividing step is performed on the GaN-based crystal layer other than a portion having a low dislocation. The method for producing a GaN-based semiconductor device according to the above (6), wherein the division is performed in a portion (for example, a non-mask region).

(8) The GaN-based crystal growth substrate is the GaN-based crystal growth substrate described in (3) above, and the GaN-based semiconductor device is a GaN-based stripe laser, which is determined by the two parallel straight lines. On a masked region or a non-masked region determined by the two parallel straight lines, a low dislocation portion (for example, on the masked region) has Ga on the masked region.
A stripe portion of the N-based stripe laser is formed so that the longitudinal directions thereof coincide with each other, and a necessary GaN-based semiconductor layer is grown to form a laminate including the GaN-based stripe laser. (6) The method according to the above (6), further comprising the step of dividing the surface parallel to the longitudinal direction of the stripe portion by dividing the plane parallel to the plane perpendicular to the laser beam and forming the resonator surface, and then dividing the individual GaN-based stripe laser by dividing the plane parallel to the longitudinal direction of the stripe portion. Of manufacturing a GaN-based semiconductor device.

(9) The division into individual GaN-based stripe lasers is performed in the division performed in a portion (for example, in a non-mask region) of the GaN-based crystal layer other than the low dislocation portion. A method for manufacturing a GaN-based semiconductor device according to the above (8).

[0015]

In the present specification, when the lattice plane of a GaN-based crystal, which is a hexagonal lattice crystal, is designated by four Miller indices (hkil), for convenience of description, if the index is negative, it is preceded by the index. The notation is given with a minus sign, and the description method according to the general Miller index is used except for the notation method regarding the negative exponent. Therefore, in the case of a GaN-based crystal, there are six prism surfaces (singular surfaces) parallel to the C axis. For example, one of the surfaces is expressed as (1-100), and the six surfaces are grouped as equivalent surfaces. $ 1-10 in case
Notated as 0｝. Also, planes perpendicular to the {1-100} plane and parallel to the C axis are equivalently grouped into {11-20}.
Notation. The direction perpendicular to the (1-100) plane is [1-100], and a set of equivalent directions is <1-10
0>, and the direction perpendicular to the (11-20) plane is [11-2].
0], and a set of directions equivalent to this is denoted as <11-20>. However, in the drawings, when the exponent is negative, the exponent is indicated by adding a minus sign to the exponent, and all the notations of the Miller exponent are followed. The crystal orientation referred to in the present invention is an orientation based on a GaN crystal grown on the base substrate with the C axis as the thickness direction. Further, when the formation pattern of the mask layer is described using a crystal orientation, the crystal orientation is an orientation based on a GaN-based crystal that grows over the mask.

"Mask region" provided on base substrate
And "non-mask region" are regions defined in the base substrate surface. The region on the upper surface of the mask layer is regarded as being equal to the mask region, and is used in the description as synonymous. Further, “above the mask region” means vertically above the surface of the mask region. The same applies to the area above the non-mask area.

In the present specification, when a plurality of elements formed on a substrate are individually cut, "part A" such as "separation in a part other than a part where low dislocations are formed" and "separation in a non-mask region". The expression “divide at” means that the division is made so that the division section passes through the portion A and the division section intersects perpendicularly with the plane of each layer.

In this specification, the terms "dislocation-free state" and "there is no defect such as dislocation" mean only an ideal state in which no dislocation exists (a state theoretically existing). Means that the dislocation density is sufficiently low that the effect of the dislocation can be ignored in industry, compared to the normal dislocation density when a GaN-based crystal is grown on a sapphire substrate via a buffer layer. I do.

As a countermeasure against cracking of the GaN-based crystal layer caused by the difference between the lattice constant and the thermal expansion coefficient between the GaN-based crystal and the sapphire crystal, as shown in FIG. A mask layer 2 patterned in a lattice pattern is provided on a substrate 1, a GaN-based crystal layer 30 is grown only in a non-mask region 11, and a chip-sized GaN-based crystal layer 30 is scattered over the entire base substrate surface. In order to prevent cracks, Japanese Patent Laid-Open No.
-273337).

As a result of further studies by the present inventors, as shown in FIG. 7 (b), when the GaN-based crystal layer 30 grown in a dotted manner is further grown, It was confirmed that the growth was also performed in the lateral direction from each of the GaN-based crystal layers 30 onto the mask layer 2. In addition, the growth rate was about the same as that in the thickness direction (C-axis direction), and the crystal orientation dependence was found.

Further, Ga in the GaN-based crystal layer 30
Dislocations present in the N-based crystal have the property of being inherited from the base including the base substrate, or being generated at any growth interface, and growing together with the crystal growth. When a GaN crystal is grown from the non-mask portion as a starting point to cover the mask layer, the thickness required to cover the mask layer and the location where the low dislocation region is formed are determined in the direction of the mask layer (the mask layer and the non-mask portion). Direction of the boundary line between the GaN crystal and the GaN crystal). For example, if low dislocations are formed above the mask layer by propagating the dislocation lines upward, as shown in FIG. 7B, a region corresponding to the mask layer 2 (hereinafter referred to as a “mask region”) Is also referred to as a mask region), there is no base (growth interface) as a generation source, and thus a dislocation-free state is obtained. When this lateral growth is further advanced, as shown in FIG. 7C, the GaN-based crystal completely covers the mask layer 2 and embeds the mask layer.
At this time, it was found that a large and thick GaN-based crystal layer 3 having a very small number of defects and having no cracks was obtained in the mask region.

The GaN-based crystal growth substrate of the present invention selects a mask layer formation / crystal growth method, utilizes low-dislocation, high-quality crystals formed on a mask region or a non-mask region, and uses the low-dislocation quality crystal. This is for forming a GaN-based semiconductor element (hereinafter, also simply referred to as an “element”) at a dislocation portion. In addition, it is important to limit the width of the mask region / non-mask region to the width of the active portion of the element and the whole width of the element. For example, if low dislocations are formed above the mask layer, when forming an element on this substrate, it is important to form the mask region at least immediately below the active portion of the element. As a result, a high-quality element can be ensured with a minimum mask area.

Also, on the GaN-based crystal growth substrate,
When a GaN-based semiconductor layer is stacked and a stacked body including a large number of elements is formed and then divided into individual elements, for example, if low dislocations are formed above the mask layer, a non-mask region Is preferable as a preferred embodiment. In this case, the GaN formed in the non-mask region
Since the system crystal layer has a low quality with many defects as described above, it is a region unsuitable for element formation. By using this region as a region for dividing, waste such as breaking a high-quality crystal portion at the time of division is eliminated, and a limited area of the base substrate surface and a high-quality crystal portion growing laterally can be more efficiently used. One preferred embodiment that can be used. For that purpose, the mask layer is patterned so that the part to be divided passes through the non-mask region. Conversely, if low dislocations are to be formed above the non-mask region, a preferable mode is to cut the mask region.

[0024]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows the GaN of the present invention.
FIG. 1A is a view showing an example of a substrate for system crystal growth, and FIG.
Is a view of the substrate surface, and FIG. 1B is a view of FIG.
FIG. 2 is a diagram of the substrate as viewed from the X direction in the figure. As shown in the figure, a surface of a base substrate 1 on which a GaN-based crystal can be grown,
A mask region 12 covered with the mask layer 2 and a non-mask region 11 where the base substrate surface is exposed are formed. The mask layer is hatched.

The element to be manufactured is not limited, but includes, for example, a light emitting element, a light receiving element, a power device and the like. As the light emitting element, GaN as described above was used.
Light emitting diodes and GaN-based semiconductor lasers. Power devices include microwave FETs, power MOSFETs, and HBTs (Heterojunction Bipolar Traps).
nsistor), MMIC (Monolithic Microwave Integrate)
d Circuit).

If the width of the element is exemplified by a light-emitting element, for example, the width shown in FIG. 5 is a typical example. FIG. 5 (a) shows G when the GaN crystal is used as the substrate 1.
This is an aN-based LED, in which the entire element is a simple rectangular parallelepiped, and the width B of the element is equal to the width A of the active portion a. FIG.
(B) is a GaN-based LED using a sapphire crystal as a substrate. Since the substrate is an insulator, the electrode arrangement on the upper surface is as shown in the figure, and the width A of the active portion is larger than the width B of the element. small. FIG. 5C shows a GaN-based stripe laser using a sapphire crystal as a substrate. Due to the stripe structure, the active portion (stripe) is wider than the width B of the element as compared with the LED shown in FIG. 5B. The width A of the part (1) is even smaller.

The width of the stripe portion in the stripe laser is, for example, the width of the stripe member in a mode in which the stripe member is embedded, and the width of the stacked body is narrower than the distance between the two surfaces of the resonator. The width of the stacked body is the width of the stacked body in a mode in which the shape of the stacked body itself is a stripe shape, and the width of the electrode in the mode in which a portion corresponding to a portion directly below the electrode in the active layer is a striped portion. The portion regarded as the width of the stripe portion differs depending on the mode. FIG. 5C shows an example in which the width of the stripe portion is smaller than the width of the active layer.

FIG. 5 shows the width of the element and the outer peripheral shape including the width.
Then, the width and the depth dimension in the direction perpendicular to the paper are different depending on the type of the element, and there are also large-area ones such as an LED array.
200 μm to 500 μm in width, 200 μm to 100 in depth
It is about 0 μm.

The base substrate may be any substrate on which a GaN-based crystal can be grown. For example, sapphire, crystal, Si
C or the like may be used. Above all, C surface of sapphire, A
A 6H-SiC substrate, particularly a C-plane sapphire substrate, is preferred. In addition, ZnO, Mg for reducing the difference in lattice constant and thermal expansion coefficient with the GaN-based crystal on the surface of these materials.
It may be provided with a buffer layer such as O or AlN.

In particular, it is important to select a base substrate having a lattice constant as close as possible and a thermal expansion coefficient as close as possible to the GaN-based crystal to be grown, so that defects such as dislocations and cracks are inherently reduced. It is desirable in that it hardly occurs. Further, it is preferable that the mask layer has excellent resistance to high heat and etching when forming a thin film of a mask layer described later. From this point, the base substrate has at least its surface layer is _{In X Ga Y Al Z N (} 0 ≦ X ≦ 1,0 ≦
Y ≦ 1, 0 ≦ Z ≦ 1, X + Y + Z = 1). Specifically, a MOV is placed on a sapphire substrate.
A layer in which a buffer layer of ZnO or AlN or the like and then a thin layer of GaN or GaAlN are sequentially formed by the PE method can be suitably used. With such a base substrate, the density of dislocations newly generated in the GaN-based crystal grown on the base substrate can be suppressed low, and good crystallinity can be obtained.

The mask layer is substantially free of its own surface.
A material that cannot grow a GaN-based crystal is used. like this
For example, an amorphous material is exemplified as a simple material.
Nitride or oxidation of Si, Ti, Ta, Zr, etc. as crystalline material
Object, ie, SiO_Two, SiN _X, SiO_1-XN_X, Ti
O_Two, ZrO_TwoEtc. are exemplified. Especially excellent in heat resistance
Si that is relatively easy to form and etch
O_Two, SiN_X, SiO_1-XN_XIs suitable and
A multilayer structure of these materials may be used.

The mask layer is formed, for example, by vacuum deposition, sputtering,
After the substrate is formed so as to cover the entire surface of the substrate by a method such as CVD, the photosensitive resist is patterned by a usual photolithography technique, and a part of the substrate is exposed by etching.

The pattern for forming the mask layer (mask region) is not particularly limited, and may be a lattice, a stripe, a dot, or the like. When the base substrate surface is entirely covered with a mask layer and an opening is provided in the mask layer to expose the base substrate surface therein, the opening may have any shape, such as a circle,
Ellipses, stars, squares, and other polygons are acceptable. If a low dislocation portion is formed above the mask region, the mask region 1
2 is <1-- of the GaN-based crystal grown on the base substrate 1.
A shape including at least two parallel straight lines extending in the <100> direction is included in the outer shape line. In the example of FIG. 1, the mask regions are provided in a linear band shape, and are arranged at intervals in a stripe shape. As shown in one of the mask regions 12, each mask region is a band-shaped region determined by two parallel straight lines y1 and y2 extending in the <1-100> direction. If a low dislocation portion is formed above the non-mask region, the mask region 12 includes at least two parallel straight lines extending in the <11-20> direction of the GaN-based crystal grown on the base substrate 1 in the outline. It is formed as a shape.

When the outline of the mask region, that is, the boundary between the mask region and the non-mask region includes a straight line in the <1-100> direction, the {11-20} plane of the GaN-based crystal becomes It is secured as a surface that grows along the upper surface. Since the {11-20} plane is an off-facet plane, the GaN-based crystal grows faster in the lateral direction than the facet {1-100} plane.

In the present invention, when a low dislocation portion is formed above the mask region, the width w1 of the two parallel straight lines y1 and y2 extending in the <1-100> direction is defined as the width of the element to be manufactured. In particular, the width should be at least immediately below the active portion. Thus, as shown in FIGS. 4B and 6, a high-quality crystal portion on the mask region can be efficiently used for the element. Hereinafter, a case where a low dislocation portion is formed above the mask region will be described with a specific example.

In the case where a low dislocation portion is formed above the mask region, it is preferable to form the mask layer so that two parallel straight lines extending in the <1-100> direction have outer diameters. The width of the mask region in the <11-20> direction may be at least a width that can exist immediately below the active portion, and may be arbitrarily selected from the width of the active portion to the entire width of the element. For example, in the case of a stripe laser, as described above, the width of the stripe is about 2 μm to about 1000 μm for the entire element, and therefore the width of the mask region in the <11-20> direction is preferably 2 μm to 1000 μm accordingly. Further, even in the case of an element having a larger area such as an LED array, at least the width of the mask region in the <11-20> direction is determined from the width of the active portion to the entire width.

It is assumed that a low dislocation portion is formed above the mask region. Also, when the mask region is striped as shown in FIG. 1 and an element is formed on each strip-shaped mask region (individual strip-shaped mask regions). On the mask region, one element is formed in the width direction and a large number of elements are formed in the longitudinal direction by division.) The number of bands in the mask region and the number of element rows are set to one. In the case of making a one-to-one correspondence, the width of the non-mask region sandwiched between the mask regions may be a width that can be divided. For example, in a device as shown in FIG. 5C, when the width of the mask region is set to the width of the active portion, the width of the mask region is minimized. It is necessary to ensure at least a width that allows the cut surface to pass through the non-mask regions on both sides when separating into non-mask regions, and the width of the non-mask region is maximized.

In the case where low dislocations are formed above the mask region and the width of the active portion is smaller than the width of the entire device, and the width of the mask region is set to be the width of the active portion immediately below, the band of the mask region is used. If there is no one-to-one correspondence between the number of elements and the number of element columns, any number of mask areas may be formed in areas other than the active part in the area immediately below the elements.

On the other hand, when the width of the mask region takes the maximum width of the element, the width of the non-mask region may be the minimum width. In the present invention, when low dislocations are formed above the mask region, the non-mask region serves as a starting point for growing the GaN-based crystal layer and also serves as a cutting region for cutting.
Therefore, for example, in the case of dividing by breaking, there is almost no loss width, and it is sufficient to consider not the width necessary for the division but the width necessary as a starting region for crystal growth. In the case of cutting by cutting with a diamond rotary blade, a loss width of about 20 μm to 50 μm is required.

From the above point, when forming a low dislocation portion above the mask region, the width of the non-mask region is 0.5 μm.
m to 5 mm, particularly about 1 μm to 1 mm.

The embodiment shown in FIG. 2 is a variation of the embodiment shown in FIG. 1, and is not limited to the width in the <11-20> direction.
The width in the <1-100> direction also corresponds to the shape of the element. That is, each mask region is a square region including two parallel sides y3 and y4 extending in the <1-100> direction and two parallel sides x1 and x2 extending in the <11-20> direction. This square shape is formed according to the shape of the target element. If a low dislocation portion is formed above the mask region, the width in the <11-20> direction or <1-20>
Any one of the widths in the −100> direction may be equal to or greater than the width of the active part of the element and equal to or less than the entire width of the element, and the other may be equal to or greater than the width of the active part of the element, even if it is a plurality of elements. Often,
Not limited. In the example of FIG. 2, this mask area is <1
They are arranged in a matrix in the <1-20> direction and the <1-100> direction.

In the embodiment shown in FIG. 2, if a low dislocation portion is formed above the mask region, it is one preferable embodiment to make one element correspond to one square mask region. For example, if the length w1 of one side of one mask region in the <11-20> direction is the width A of the stripe portion of the stripe laser shown in FIG.
For example, the length w2 of one side in the 0> direction is set as the total length of the stripe portion. According to such an embodiment, <11-20>
Both the <1-100> direction and the <1-100> direction can be divided in the non-mask region.

The embodiment shown in FIG. 3 is another variation of the embodiment shown in FIG. 1, and the mask area is a grid-like area. As shown in the figure, the mask area is <1-10
A band-like region determined by two parallel straight lines y5 and y6 extending in the <0> direction and a band-like region determined by two parallel straight lines x3 and x4 extending in the <11-20> direction are superimposed and formed in a grid. Area. If a low dislocation portion is formed above the mask region, two straight lines y5 and y5
6 are formed in accordance with the shape of the target element, and a rectangular area where these two-directional band-shaped areas intersect (the hatched area in FIG. (The region shown) is a shape that can cover at least the active portion of the element.

According to the embodiment shown in FIG. 3, if a low dislocation portion is formed above a mask region and a semiconductor element is formed in a rectangular region where the above-described two-direction band-like regions intersect, the non-mask regions can be separated from each other by < Individual elements can be obtained by dividing the device along a line connecting in the <11-20> direction and along a line connecting in the <1-100> direction.

When a low dislocation portion is formed above a mask region of the GaN-based crystal growth substrate, a semiconductor element is formed on each mask region. For example, a plurality of semiconductor elements formed on the mask region are formed. As a means for separating the individual pieces, a method using point scribing and braking, scribing using a diamond rotary blade, and the like can be given.

In the method of manufacturing a GaN-based semiconductor device according to the present invention, the substrate for growing a GaN-based crystal described above is used.
A GaN-based crystal is grown as shown in FIG. 1 and further used as a substrate to form a semiconductor device as shown in FIG. 4 or FIG. 6, and a portion other than a portion having low dislocation (for example, This is a method in which a semiconductor device is individually divided by forming a cross section mainly in a non-mask region in the case of low dislocation.

The growth of the GaN-based crystal starts from a non-mask region of the base substrate as a starting point. As the growth is continued, the space between the mask layers is filled with a GaN-based crystal as shown in FIG. 7A, and further, as shown in FIG.
The GaN-based crystal swells higher than the upper surface of the mask layer. At this time, the GaN-based crystal starts growing not only in the height direction (C-axis direction) but also in the lateral direction starting from the side surface of the bulging portion. Eventually, it merges with the growing crystal starting from the adjacent non-mask region, and eventually, as shown in FIG. 7C, completely covers the mask layer 2 and continues to grow in the thickness direction. A GaN-based crystal layer is formed.

As shown in FIG. 7 (c), depending on the mask layer formation pattern and the selection of crystal growth conditions, the dislocation lines that have entered the GaN-based crystal layer from the non-mask region are directly above the GaN-based crystal layer. , And a portion such as a dislocation may be inherited in a portion on the non-mask region. However, in this case, at least the portion on the mask region is formed by lateral growth starting from the side surface of the bulging portion (the surface where defects such as dislocations do not exist). Is an extremely high-quality crystal having no. In addition, the direct contact portion between the GaN-based crystal layer and the base substrate is only the non-mask region, the contact area is small, and the GaN-based crystal layer is hardly affected by the difference in the coefficient of thermal expansion. There is also the advantage that it can be grown in

The material to be grown as a crystal layer is Ga
Not only N but also a GaN-based semiconductor may be used. For example, the formula In _X Ga _Y Al _Z N (0 ≦ X ≦ 1, 0 ≦ Y ≦ 1, 0
≦ Z ≦ 1, X + Y + Z = 1).

The method of growing the GaN-based crystal is not limited, and examples thereof include HVPE, MOVPE (MOCVD), and MBE. In particular, HVPE is preferable because it has an advantage that the growth rate in the C-axis direction is very high. When a thin film is formed, the MOCVD method is preferable.

Next, as shown in FIG.
A portion of the N-based crystal layer on the mask region is used as a GaN-based crystal substrate, and the semiconductor layer 4 is grown so that at least the active portion is located on the mask region to form a stacked body including a required number of elements. The example in the figure is a GaN-based L
In the case of ED, the width of the mask, the width of the element, and the width of the active portion are equal. The active part is a part that functions as an element, and is a part that emits light including a pn junction in a light emitting element. For example, in a double heterojunction structure of an LED, it is an active layer, and in a stripe laser, it is a stripe portion.

Next, as shown in FIG. 4B, a laminate including a required number of elements is divided to obtain individual elements. Removal of the base substrate is optional.

When the element is a stripe laser, the stripe portion has a longitudinal direction (has directivity);
In addition, it is preferable to form and divide the element by paying attention to the fact that the element has a resonator. For example, in the case described above, when the mask region is formed in a stripe shape as shown in FIG. 1 and a low dislocation portion is formed above the mask region,
First, as shown in FIG. 6, the longitudinal direction of a portion to be a stripe portion is defined as the longitudinal direction of a band of each mask region,
It is efficient to continuously form a plurality of stripe lasers on the mask region. For the above,
First, the entire laminated body is divided along a plane perpendicular to the longitudinal direction of the stripe portion (for example, in FIG. 6, division along S1 and S2).
Then, as shown in the front part of FIG.
An element adjacent in the <0> direction is continuously connected. Apply the necessary processing as a reflector to the end face of each striped portion appearing on the dividing plane to finish the resonator collectively, and then divide the plane parallel to the longitudinal direction of the stripe as a dividing plane (For example, in FIG. 6, U1 to U
4), and it is efficient to finish individual GaN-based stripe lasers.

[0054]

【Example】

Example 1 In this example, a mode in which a low dislocation portion is formed above a mask region in a GaN-based crystal grown to cover a mask layer will be described. After fabricating a GaN-based crystal growth substrate having a mask area equal to the shape of each element,
An aN crystal layer is grown to form a crystal substrate, a double heterojunction structure is formed on a mask region to form an LED, and the device is divided into non-mask regions to divide the device into individual devices. I got

[Production of GaN Crystal Growth Substrate] Diameter 2
Inch, 330 μm thick, C-plane sapphire substrate
Using an OVPE apparatus, a 20-nm-thick AlN buffer layer was grown at a low temperature, and then a 1.5-μm thin GaN layer was grown to serve as a base substrate. On the surface of this substrate, SiO ₂
A mask layer made of a thin film and having the form shown in FIG. 2 was formed by a sputtering method to obtain a GaN-based crystal growth substrate according to the present invention.

The formation pattern of the mask layer is such that one mask region is 290 μm × <1-10> in the <11-20> direction.
0> 290 μm in the direction, which is a shape that matches the active layer of the target LED. The <11-20> direction, <1-10>
0> direction, both were arranged at intervals of 10 μm. Therefore, the pitch between the centers of the mask regions is <11-20>
The direction and the <1-100> direction are both 300 μm. In addition, the non-mask region has a lattice shape in which strip-shaped regions having a width of 10 μm are orthogonal to each other.

[Formation of GaN Crystal Layer] The above-mentioned GaN-based crystal growth substrate was loaded in an HVPE apparatus, and as shown in FIG.
An N crystal layer was formed. The GaN crystal also grew in the lateral direction on the mask layer and completely covered the mask layer. The surface flatness of the n-type GaN crystal layer was good.

[Formation of Light-Emitting Element] An n-GaN layer / n-AlG
aN layer / n-InGaN layer / InGaN layer (active layer) /
A p-AlGaN layer / p-GaN layer were sequentially grown, and further, respective electrodes on the p-type side and the n-type side were formed, thereby completing a stacked body including LEDs having a double hetero junction structure in a matrix.

[Dividing into Individual Elements] As shown in FIG. 4B, a point scriber cuts and divides the lattice-shaped non-mask region to separate the individual LEs.
D was obtained.

According to the present example, it was confirmed that elements could be formed with the mask region efficiently corresponding to the active portions, and that the non-mask region could be divided into individual elements. In addition, this LED and a conventional LE using a low-quality GaN-based crystal substrate formed on a non-mask region and including dislocations are used.
D, when compared in terms of emission luminance and life characteristics, the LED obtained by the manufacturing method of the present invention,
It was found that both the light emission luminance and the life characteristics were improved 1.5 times.

Example 2 In this example, the target element to be formed was a stripe laser, and as shown in FIG. 1, the mask layer was a parallel stripe extending in the <1-100> direction of the GaN crystal. The production of the GaN-based crystal growth substrate was performed in the same manner as in Example 1, and the pattern of the mask layer was changed to a width of 150 μm and a center pitch of 300 μm.
m.

[Formation of Stripe Laser Structure] A GaN crystal layer having a thickness of 100 μm is formed on a GaN-based crystal growth substrate to form a substrate, on which an n-GaN layer / n
-AlGaN layer / n-GaN layer / InGaN multiple quantum well layer / p-AlGaN layer / p-GaN layer / p-AlGa
An N layer / p-GaN layer is sequentially grown, and the laminate is subjected to RIE.
(Reactive Ion Etching) etching was performed leaving a width of 8 μm to form a stripe as shown by 4 in FIG. At this time, the alignment was performed so that the stripe was formed substantially at the center on the mask layer, and the orientation of the stripe was accurately adjusted in the <1-100> direction. By polishing C
The surface sapphire substrate was removed to make the entire thickness 80 μm.

[Dividing into individual elements] A plane perpendicular to the longitudinal direction of the stripe is taken as a dividing section, that is, S1 in FIG.
Cleavage was performed at S2 and parallel to them at a pitch of 500 μm (cleavage on the M plane), and a large number of devices in a state where adjacent elements were connected in the <11-20> direction were obtained. After the necessary coating was applied to each reflector surface in a lump to finish the resonator, it was cut along U1-U4 in FIG. 6 to obtain individual laser chips.

According to the present embodiment, it was confirmed that, similarly to the first embodiment, an element can be formed with a mask region efficiently corresponding to a stripe portion. In addition, it has been found that a stripe laser can be obtained efficiently by setting the direction of the stripe and the procedure of division as described above.

Embodiment 3 In this embodiment, a stripe laser similar to that of Embodiment 2 is manufactured, but differs from Embodiment 2 in the following points. Mask layer,
The GaN crystal was formed into parallel stripes extending in the <11-20> direction. The specification of the parallel stripes is such that the width of the band-shaped mask region is 50 μm, and similarly, the width of the non-mask region is 250 μm.

[Formation of Substrate] The substrate for growing a GaN-based crystal on which the above-mentioned parallel stripe-shaped mask layer is formed is placed in an HVPE apparatus, at a temperature of 1000 ° C., trimethylgallium (TMG) as a Ga source, and ammonia as an N source. Then, silane was flowed as a dopant raw material, and a GaN crystal was grown using a growth atmosphere gas of hydrogen until the mask layer was covered. When the upper surface of the GaN crystal layer became flat, the thickness of this layer was 100 μm.

[Formation of Stripe Laser Structure] An n-GaN layer / n-AlGaN layer / n-G
An aN layer / InGaN multiple quantum well layer / p-AlGaN layer / p-GaN layer / p-AlGaN layer / p-GaN layer are sequentially grown, and the laminate is subjected to RIE (Reactive Ion Etching).
The film was etched leaving a width of 8 μm to form a stripe. At this time, the alignment was performed so that the stripe was formed substantially at the center on the non-mask region, and the orientation of the stripe was accurately adjusted in the <11-20> direction. The C-plane sapphire substrate was removed by polishing, so that the entire thickness was 80 μm.

[Division into individual elements] Cleaving is performed at a pitch of 500 μm (cleavage on the M plane) using a plane orthogonal to the longitudinal direction of the stripe as a division plane, and elements adjacent in the <1-100> direction are separated from each other. Many connected things were obtained. The required coating was applied to each reflector surface in a batch to finish the resonator, and then cut to obtain individual laser chips.

According to the present example, it was confirmed that the dislocation was reduced above the non-mask region, and that the element could be efficiently formed in correspondence with the laser stripe portion. In addition, it was found that a stripe laser can be obtained efficiently as in Example 2 by setting the direction of the stripe and the procedure of division as described above.

[0070]

By using the substrate for growing a GaN-based crystal according to the present invention, a crystal of good quality formed either above the mask region or above the non-mask region can be more efficiently used in the active portion of the device. Can correspond. In addition, the non-mask region serving as the starting point of the crystal can be used for the final division of the device. Therefore, loss of the region formed with high quality is small, and the limited area of the original base substrate can be effectively used.

[Brief description of the drawings]

FIG. 1 is a view showing an example of a GaN-based crystal growth substrate of the present invention.

FIG. 2 is a view showing another example of the GaN-based crystal growth substrate of the present invention.

FIG. 3 is a view showing another example of the GaN-based crystal growth substrate of the present invention.

FIG. 4 is a graph showing Ga using the GaN-based crystal growth substrate of the present invention.
It is a figure showing the manufacturing process of N type light emitting diode.

FIG. 5 is a diagram showing an example of a width of a target element and a width of an active portion thereof.

FIG. 6 is a view showing Ga using the GaN-based crystal growth substrate of the present invention.
It is a perspective view showing an example of a state in a manufacturing process of an N system stripe laser. The dashed lines at the left and right ends in the figure indicate break lines. Also, in the figure, electrodes are omitted.

FIG. 7 shows GaN on a GaN-based crystal growth substrate of the present invention.
FIG. 3 is a view showing formation of a system crystal layer.

[Explanation of symbols]

 Reference Signs List 1 base substrate 2 mask layer 3 GaN-based crystal layer 11 unmasked area 12 masked area

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Kazuyuki Tadomo 4-3 Ikejiri, Itami-shi, Hyogo Mitsubishi Electric Cable Industry Co., Ltd. Itami Works

Claims (12)

[Claims] 1. A GaN-based crystal growth substrate used for manufacturing a GaN-based crystal substrate constituting a GaN-based semiconductor element, wherein a part or all of a base substrate surface on which a GaN-based crystal can be grown is provided. A mask layer is provided so as to form a mask region and a non-mask region. The mask layer is made of a material from which a GaN-based crystal cannot grow substantially from its own surface. When the GaN-based crystal is grown to cover the upper surface of the mask layer using the mask region as a starting point of growth, the width of a portion where low dislocations are present in the crystal is equal to or larger than the width of the active portion in the GaN-based semiconductor device. A substrate for growing a GaN-based crystal, which is a pattern formed to be able to be: 2. A GaN-based crystal growth substrate used for manufacturing a GaN-based crystal substrate constituting a GaN-based semiconductor device, wherein a part or all of a base substrate surface on which a GaN-based crystal can be grown is provided. A mask layer is provided so as to form a mask region and a non-mask region. The mask layer is made of a material from which a GaN-based crystal cannot grow substantially from its own surface, and the mask region is formed on the base substrate. The outline includes two parallel straight lines extending in the <1-100> direction of the GaN-based crystal that grows on the surface, and the width of the two parallel straight lines is equal to or smaller than the width of the GaN-based semiconductor device, and The substrate for growing a GaN-based crystal according to claim 1, wherein the substrate has a width equal to or greater than the width of the active portion. 3. The outline includes two parallel straight lines extending in the <11-20> direction of the GaN-based crystal grown on the base substrate, and the width of the parallel two straight lines is 2. The GaN-based crystal growth substrate according to claim 1, wherein the width is not more than the width of the GaN-based semiconductor element and not less than the width of the active portion of the element. 4. A non-mask region is a band-like region determined by the two parallel straight lines, and a plurality of band-like mask layers are formed at equal intervals so that the non-mask region becomes parallel stripes. The GaN according to claim 2 or 3, wherein
Substrate for crystal growth. 5. The GaN-based semiconductor device is a GaN-based stripe laser, wherein the active portion width is the width of a stripe portion in the stripe laser, and the direction in which the two parallel straight lines extend in the stripe laser. The Ga according to any one of claims 2 to 4, which is a longitudinal direction of the stripe portion.
Substrate for N-based crystal growth. 6. The Ga according to claim 1, wherein the GaN-based semiconductor device is a GaN-based light emitting diode.
Substrate for N-based crystal growth. 7. A base substrate having at least a surface layer of I
_{n X Ga Y Al Z N (} 0 ≦ X ≦ 1,0 ≦ Y ≦ 1,0 ≦ Z
2. The substrate for growing a GaN-based crystal according to claim 1, wherein ≤1, X + Y + Z = 1). 8. The G according to claim 1, wherein
using a substrate for growing an aN-based crystal, growing a GaN-based crystal layer from a non-mask region on the substrate as a starting point to cover the mask layer; A step of growing a GaN-based semiconductor layer so as to form an active portion of the GaN-based semiconductor element to form a stacked body including the GaN-based semiconductor element; and a step of dividing the stacked body into individual GaN-based semiconductor elements. A method of manufacturing a GaN-based semiconductor device, comprising: 9. The G according to claim 1, wherein
using a substrate for growing an aN-based crystal, growing a GaN-based crystal layer from a non-mask region on the substrate as a starting point until the GaN-based crystal layer is covered with the GaN-based crystal layer; A step of growing a GaN-based semiconductor layer so that an active portion of the semiconductor element is formed to form a stacked body including the GaN-based semiconductor element, and a step of dividing the stacked body into individual GaN-based semiconductor elements. 9. The method for manufacturing a GaN-based semiconductor device according to claim 8, comprising: 10. The GaN-based crystal growth substrate according to claim 5, wherein the dividing in the dividing step is performed on a portion of the GaN-based crystal layer other than the low dislocation portion. 9. The method for manufacturing a GaN-based semiconductor device according to claim 8, wherein the division is performed at a part. 11. A GaN-based crystal growth substrate according to claim 5, wherein the GaN-based semiconductor element is a GaN-based stripe laser, and is determined by the two parallel straight lines. A GaN-based stripe laser is formed by forming a stripe portion of a GaN-based stripe laser on a mask region or a non-mask region where a low dislocation is formed so that the longitudinal direction thereof coincides, and growing a necessary GaN-based semiconductor layer. A laminated body is formed, and the laminated body is first divided into sections along a plane perpendicular to the longitudinal direction of the stripe section to form a resonator surface, and then a plane parallel to the longitudinal direction of the stripe section is taken as a sectional section. The method of manufacturing a GaN-based semiconductor device according to claim 9, further comprising a step of dividing into individual GaN-based stripe lasers. 12. The method of manufacturing a GaN-based semiconductor device according to claim 11, wherein the division into individual GaN-based stripe lasers is performed in a portion of the GaN-based crystal layer other than a portion where a low dislocation is formed. .