KR100454907B1 - Nitride Semiconductor substrate and method for manufacturing the same - Google Patents

Abstract

The present invention relates to a nitride semiconductor substrate and a method for manufacturing the same, comprising: at least one first nitride semiconductor layer formed by linearly patterning an upper portion of the hetero substrate; And a second nitride semiconductor layer formed on side and top surfaces of the first nitride semiconductor layer, and coalescing by a side growth method to form an empty space at an interface between the first nitride semiconductor layer and the second nitride semiconductor layer. The growth was stopped before the step 1) occurred, the mask was removed, and then a III-V nitride semiconductor thin film layer was grown by subsequent lateral growth.

Accordingly, the present invention solves problems such as crystallographic inclination, generation of defects, and increase of internal stress when forming a nitride semiconductor thin film layer having a low defect density by using the lateral growth method, and growing with a mask material. The reaction with the nitride semiconductor can be suppressed, and an effect that can be applied to substrates of optical devices such as LEDs and LDs and electronic devices such as HEMTs occurs.

Description

Nitride semiconductor substrate and method for manufacturing the same

The present invention relates to a nitride semiconductor substrate and a method of manufacturing the same, and more particularly, to stop the growth before coalescence of the laterally grown nitride semiconductor thin film occurs, and to remove the mask to remove the group III-V group. By growing a nitride semiconductor thin film layer, it is related with the nitride semiconductor substrate which can suppress generation | occurrence | production of a stress and a defect between a mask material and the laterally grown thin film layer, and its manufacturing method.

In general, group III-V nitride semiconductors such as gallium nitride are widely used in high temperature and high power electronic devices in addition to light emitting devices and light receiving devices that emit light ranging from ultraviolet rays to visible light.

In order to manufacture a nitride device, it is necessary to form a single crystal thin film having a low defect density. To date, nitride semiconductor single crystals have been grown on dissimilar substrates such as sapphire (Al ₂ O ₃ ), silicon carbide (SiC), silicon and gallium arsenide (GaAs).

In the gallium nitride thin film grown by hetero epitaxy, very high density of crystal defects exist, and these crystal defects lower the luminous efficiency of the optical device and the electronic device and function as a leakage passage of the current. By performing this, the performance of the device is lowered.

Therefore, various attempts have been made to reduce the defect density in heteroepitaxial growth, and at present, nitride semiconductor single crystal thin film growth by Lateral epitaxial overgrowth is the most widely used method.

1A and 1B illustrate a conventional manufacturing process of a nitride semiconductor single crystal thin film by lateral growth. In FIG. 1A, a first gallium nitride thin film 11 is grown on top of a hetero substrate 10 such as sapphire, silicon carbide, and silicon. The linear repetitive mask pattern 12 is deposited on the first gallium nitride thin film 11 by a dielectric film or a metal thin film such as silicon oxide film SiO ₂ , silicon nitride film Si ₃ O ₄ .

After the mask pattern 12 is deposited, when the second gallium nitride thin film is grown, gallium nitride is grown on the surface of the exposed first gallium nitride thin film 11 where the mask pattern 12 is not present. In the mask pattern 12, lateral growth is performed to produce a second gallium nitride thin film 13 having an overall flat surface (FIG. 1B).

The dotted line in FIG. 1B indicates a defect, and among these defects, in the second gallium nitride thin film 13 without the mask pattern 12, the defect 14 propagates upwards, but under the mask pattern 12. In the region 16 of the first gallium nitride thin film, propagation of defects is suppressed, and a region free of defects is formed by lateral growth.

In the region where the laterally grown portions meet, a new defect 15 is formed and propagated to the surface of the second gallium nitride thin film 13.

Although the side growth method using such a mask is effective in obtaining a region having a small defect density, stress is generated by the reaction with the mask during side growth above the mask, and defects as shown in FIG. 1B are generated. It has a problem such as.

In particular, since the mask material is likely to deteriorate in a high-temperature and ammonia gallium nitride growth atmosphere, the reduction of the defect density in the lateral growth region is not complete, and phenomena such as crystallographic tilting occur. have.

Therefore, when a lot of stress due to the mask is generated, a phenomenon in which the substrate is bent may occur, which may cause a lot of difficulties in performing a process of manufacturing a device using a gallium nitride single crystal thin film, resulting in a decrease in production yield.

2A to 2C are diagrams illustrating a process of manufacturing a nitride semiconductor single crystal thin film by Pendio, which is one of the conventional lateral growth methods, wherein the first gallium nitride thin film is formed on a dissimilar substrate 20 such as sapphire, silicon carbide, and silicon. (21), a dielectric film or a metal thin film such as silicon oxide film (SiO ₂ ), silicon nitride film (Si ₃ O ₄ ) shown in FIG. 1A is grown on top of the first gallium nitride thin film 21. By depositing a linear repetitive mask pattern 22 to be etched to expose the dissimilar substrate 20, the first gallium nitride thin film 21 'is separated from each other, and the mask pattern 12 is left. Release (Fig. 2b).

Thereafter, when the second gallium nitride thin film 23 is grown, it grows to the top while lateral growth is made, and also to the side of the mask pattern 22 (Fig. 2C).

When the second gallium nitride thin film 23 grown in this way is coalesced with each other, a substrate made of the low density second gallium nitride thin film 23 is formed (FIG. 2D).

At this time, a defect exists in the site of coalescing the gallium nitride layer that is laterally grown.

In the conventional method of growing a gallium nitride substrate, as shown in FIG. 3, a stress is generated between the side-grown second gallium nitride thin film layer 23 and the mask pattern 22, thereby creating additional defects and crystallography. Skew occurs.

Figure 3 is a schematic diagram of the crystallographic tilting phenomenon in the gallium nitride lateral growth by the conventional method, the arrow indicates the (0001) direction of the gallium nitride thin film, the direction of the arrow should have a uniform direction, It has crystallographically inclined uneven orientation.

The crystallographic inclination of the grown gallium nitride layer is caused by deterioration of the mask material because the growth of the gallium nitride thin film is performed in a toxic atmosphere using high temperature and ammonia.

This crystallographic skew not only produces high density defects in the thin film but also interferes with the planarization of the surface.

In addition, the conventional method described above may generate defects due to stress generated at the interface between the grown gallium nitride layer and the mask material, and the substrate may be bent due to such stress, making the manufacturing process of the nitride semiconductor light emitting device difficult, and the yield It has a problem of deterioration.

Accordingly, the present invention was devised to solve the above problems, and by using a lateral growth method, an empty space is formed by removing a mask pattern between a seed layer and a grown III-V nitride semiconductor thin film layer. The purpose is to provide a nitride semiconductor substrate with reduced internal stress and low defect density.

Another object of the present invention is to stop the growth before coalescence occurs in the lateral growth method, and to remove the mask to form a III-V nitride semiconductor thin film layer through subsequent lateral growth, thereby forming a gap between the mask material and the lateral growing thin film layer. To provide a method for forming a nitride semiconductor substrate thin film layer capable of suppressing the generation of stress and defects.

A preferred aspect for achieving the above object of the present invention comprises: at least one first nitride semiconductor layer formed by linearly patterning the upper portion of the hetero substrate;

Consists of a second nitride semiconductor layer formed on the side and top surface of the first nitride semiconductor layer,

A nitride semiconductor substrate is provided wherein an empty space is formed above the first nitride semiconductor layer and the second nitride semiconductor layer.

According to a preferred aspect of the present invention, a first nitride semiconductor layer is grown on a dissimilar substrate, and a linear repetitive mask pattern is deposited on the first nitride semiconductor layer. A first step of doing;

A second step of etching the first nitride semiconductor layer by using the mask pattern as a mask so as to expose the hetero substrate, and leaving the mask pattern;

A third step of laterally growing a second nitride semiconductor after the second step;

A fourth step of stopping growth of the second nitride semiconductor before coalescence of the second nitride semiconductor occurs on top of the mask pattern;

A fifth step of wet etching the mask pattern after the fourth step;

And after the mask pattern is etched, a sixth step of growing the second nitride semiconductor layer by lateral growth to grow a second nitride semiconductor layer having a flat surface formed of coalescence. This is provided.

1A and 1B illustrate a process chart of manufacturing a nitride semiconductor single crystal thin film by conventional lateral growth.

2A to 2C are diagrams illustrating a process of manufacturing a nitride semiconductor single crystal thin film by a peneo method, which is one of the conventional lateral growth methods.

Figure 3 is a schematic diagram of the crystallographic tilting phenomenon when the side growth of gallium nitride by the conventional method.

3A to 3C are process diagrams for manufacturing a semiconductor laser diode array in which optical interference between ridges and ridges does not occur according to the present invention.

4A to 4E are process charts for the production of nitride semiconductor single crystal thin films by lateral growth of the present invention.

<Description of the symbols for the main parts of the drawings>

10, 20, 50: dissimilar substrate 11, 21: first gallium nitride thin film

12, 22, 52: mask pattern 13, 23: second gallium nitride thin film

14 Defect 51 AlGaN Seed Layer

53: AlGaN layer 54: empty space

Hereinafter, exemplary embodiments of the present invention will be described with reference to the accompanying drawings.

4A to 4E illustrate a process chart of manufacturing a nitride semiconductor single crystal thin film by lateral growth of the present invention. First, an AlGaN seed, which is a group III-V first nitride semiconductor layer, is formed on top of a hetero substrate 50 such as sapphire, silicon carbide, and silicon. A layer 51 is grown (FIG. 4A), and a dielectric film such as a silicon oxide film (SiO ₂ ), a silicon nitride film (Si ₃ O ₄ ), or a metal such as W, Ta, and Pt is formed on the AlGaN seed layer 51. The thin film is deposited with a linear repetitive mask pattern 52 (FIG. 4B).

Using the mask pattern 52 as a mask, the AlGaN seed layer 51 is removed by etching to expose the hetero substrate 50, and the mask pattern 52 is left (FIG. 4C).

Thereafter, the AlGaN layer 53, which is the second nitride semiconductor layer, is laterally grown, while the AlGaN is laterally grown for a time until coalescence of the lateral growth of the AlGaN layer 53 occurs on the mask pattern 52. 4d)

Here, the first and second nitride semiconductor layers are preferably the same material and do not need to be the same.

At this time, AlGaN is grown on the side of the AlGaN seed layer 51, and side growth of AlGaN occurs on the mask pattern 52, and AlGaN is grown on the mask pattern 52. Before coalescence occurs, the growth of AlGaN is stopped.

The mask pattern 52 is then wet etched using a hydrofluoric acid (HF) solution to create an empty space 54 (FIG. 4E).

Finally, after the mask pattern 52 is etched, AlGaN is continuously grown by the lateral growth method to form an AlGaN layer 53 which is a second nitride semiconductor thin film layer having a flat surface formed of coalescence (FIG. 4F).

Here, the second grown nitride semiconductor thin film layer is preferably grown to a thickness in the range of 3㎛ ~ 500㎛.

In addition, the AlGaN preferably has a composition of Al in a range of 0 ≦ Al ≦ 0.3.

The nitride semiconductor substrate of the present invention manufactured as described above comprises at least one first nitride semiconductor layer formed separately on top of the hetero substrate; And a second nitride semiconductor layer formed on an upper surface of the dissimilar substrate and side surfaces and an upper surface of the first nitride semiconductor layer, and an empty space formed on the first nitride semiconductor layer and the second nitride semiconductor layer. Will be made.

This empty space serves as a buffer to reduce the internal stress generated between the substrate and the grown nitride semiconductor layer.

As described in detail above, the present invention solves problems such as crystallographic tilting, formation of defects, and increase of internal stress by growing after removing a mask material before coalescence occurs during lateral growth. In addition, it is possible to suppress the reaction between the mask material and the grown nitride semiconductor. Also, an empty space is formed between the grown seed nitride semiconductor and the grown nitride semiconductor, which is excellent in reducing the internal stress caused by the growth on the dissimilar substrate. There is an advantage, there is an effect that can be applied to the substrate of the optical device, such as LED, LD and electronic devices such as HEMT.

Although the invention has been described in detail only with respect to specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the spirit of the invention, and such modifications and variations belong to the appended claims.

Claims (8)

delete delete delete delete A first step of growing a first nitride semiconductor layer on top of the hetero substrate, and depositing a linear repetitive mask pattern on the first nitride semiconductor layer; A second step of etching the first nitride semiconductor layer by using the mask pattern as a mask so as to expose the hetero substrate, and leaving the mask pattern; A third step of laterally growing a second nitride semiconductor after the second step; A fourth step of stopping growth of the second nitride semiconductor before coalescence of the second nitride semiconductor occurs on top of the mask pattern; A fifth step of wet etching the mask pattern after the fourth step; After the mask pattern is etched, the nitride semiconductor substrate comprising a sixth step of growing a second nitride semiconductor layer having a flat surface made of coalescence by continuously growing a second nitride semiconductor by a side growth method Way. The method of claim 5, wherein And the first nitride semiconductor thin film layer and the second nitride semiconductor thin film layer are AlGaN thin film layers. The method according to claim 5 or 6, The hetero substrate is a method of manufacturing a nitride semiconductor substrate, characterized in that any one selected from sapphire, silicon carbide and silicon. The method according to claim 5 or 6, The mask pattern is a method of manufacturing a nitride semiconductor substrate, characterized in that the dielectric film or a metal thin film.