KR100427689B1 - Method for manufacturing Nitride semiconductor substrate - Google Patents

Abstract

The present invention relates to a method for manufacturing a nitride semiconductor substrate, the first step of growing a first nitride semiconductor layer on top of the hetero substrate, and depositing a linear repeating first mask pattern on the first nitride semiconductor layer Wow; After the first step, the second nitride semiconductor is laterally grown, but before the coalescence of the second nitride semiconductor occurs on top of the first mask pattern, the growth of the second nitride semiconductor is stopped and the first mask pattern is wetted. A second step of etching; After the first mask pattern is etched, the second nitride semiconductor is continuously grown by a lateral growth method to grow a second nitride semiconductor layer having a flat surface on which the coalescence is formed. 2 The nitride thin film layer grown side by side by repeatedly performing the process of depositing a mask pattern on the nitride semiconductor layer, growing the nitride semiconductor side, stopping the growth before coalescing, mask pattern wet etching, and continuously growing the nitride semiconductor by the side growth method. The stress, defects and inclination occurring at the interface between the mask material and the mask material can be suppressed, and an effect of additionally reducing stress by forming an empty space occurs.

Description

Method for manufacturing Nitride semiconductor substrate

The present invention relates to a method for manufacturing a nitride semiconductor substrate, and more particularly, when forming a III-V nitride semiconductor thin film layer by the side growth method, the side growth is stopped, the mask material is removed, and then the side growth is performed. By repeating at least two or more times to form a combination, the present invention relates to a method for manufacturing a nitride semiconductor substrate that can suppress the stress, defects and inclination occurring at the interface between the nitride thin film layer and the mask material that is laterally grown.

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 such 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).

Therefore, very high density of crystal defects exist in the gallium nitride thin film grown by hetero epitaxy, and these crystal defects reduce luminous efficiency or reduce leakage current in optical and electronic devices. By functioning, the performance of an element is reduced.

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

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 on 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 side-grown region is not complete, and phenomena such as crystallographic tilting may be used. It forms a reading dislocation having a high density at and adversely affects the planarization of the surface. Furthermore, defects of higher density than the lower part are formed in the coalescence front where the side-grown thin films meet each other.

This crystallographic tilt phenomenon forms defects of high density inside the thin film.

FIG. 2 is a schematic diagram showing the crystallographic tilting phenomenon in the lateral growth of gallium nitride, wherein the side-grown second gallium nitride thin film 33 is between the dissimilar substrate 30 and the first gallium nitride thin film 31 and a mask pattern. As a stress generated between the 32 and the second gallium nitride thin film 33, as shown in the arrow of FIG. 2, a non-uniform (0002) crystal direction is generated.

Therefore, the presence of a large amount of stress caused by the mask causes the substrate to bend, which makes the subsequent process difficult, as well as the lattice constant and coefficient of thermal expansion that occur when the device is made of various III-V nitride thin film layers. It is combined with the stress caused by the difference and causes a problem such as cracking on the surface of the device.

Accordingly, the present invention has been made to solve the above problems, when forming the III-V group nitride semiconductor thin film layer by the lateral growth method, the lateral growth is stopped, the mask material is removed, and then the lateral growth is performed. It is an object of the present invention to provide a method for manufacturing a nitride semiconductor substrate that can suppress the stress, defects, and inclination occurring at the interface between the nitride thin film layer that is laterally grown and the mask material by repeating the method of forming the mixture. .

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

After the first step, the second nitride semiconductor is laterally grown, but before the coalescence of the second nitride semiconductor occurs on top of the first mask pattern, the growth of the second nitride semiconductor is stopped and the first mask pattern is wetted. A second step of etching;

After the first mask pattern is etched, a third step of continuing to grow the second nitride semiconductor by side growth to grow a second nitride semiconductor layer having a flat surface formed of coalescence;

Depositing a second mask pattern on the second nitride semiconductor layer on which the coalescence is formed;

After the seventh step, the third nitride semiconductor is laterally grown, but before the coalescence of the third nitride semiconductor occurs on top of the second mask pattern, the growth of the third nitride semiconductor is stopped and the second mask pattern is wetted. A fifth step of etching;

And a sixth step of growing the third nitride semiconductor layer having a flat surface formed by coalescence by continuously growing the third nitride semiconductor by etching the second mask pattern. A method of manufacturing a semiconductor substrate is provided.

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

2 is a schematic diagram showing the crystallographic tilting phenomenon in the lateral growth of gallium nitride.

3A to 3F are flowcharts of a nitride semiconductor single crystal thin film produced by lateral growth of the present invention.

<Description of Symbols for Main Parts of Drawings>

10, 30, 50: dissimilar substrate 11, 31: the first gallium nitride thin film

12, 32: mask pattern 13, 33: second gallium nitride thin film

14: defect 51, 53, 63: AlGaN layer

52, 62: mask pattern 54, 64: empty space

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

3A to 3F 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. The layer 51 is grown and formed on top of the AlGaN seed layer 51 by a dielectric film such as silicon oxide film (SiO ₂ ), silicon nitride film (Si ₃ O ₄ ) or a metal thin film such as W, Ta, and Pt. Repetitive first mask pattern 52 is deposited (FIG. 3A).

Lateral growth of an AlGaN layer 53, which is a second nitride semiconductor layer, is formed on the AlGaN seed layer 51, which is the first nitride semiconductor layer, and laterally grown on the AlGaN layer 53, on the first mask pattern 52. Before the coalescing occurs, the growth of AlGaN is stopped (Fig. 3b).

Then, the first mask pattern 52 is wet etched using a hydrofluoric acid (HF) solution to form a first empty space 54 (FIG. 3C).

After the first mask pattern 52 is etched, AlGaN is continuously grown by lateral growth to form an AlGaN layer 53, which is a second nitride semiconductor thin film layer having a flat surface formed of coalescence (FIG. 3D). )

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

Thereafter, a second mask pattern 62 is formed on the AlGaN layer 53, which is a second nitride semiconductor thin film layer formed of coalescing according to the lateral growth (FIG. 3E), and then AlGaN, which is a third nitride semiconductor thin film, is laterally formed. Growing and stopping growth of AlGaN before coalescence of lateral growth of the AlGaN layer 63 which is a third nitride semiconductor thin film layer on the second mask pattern 62 occurs, and then, as described above, the second The mask pattern 62 is removed to form an empty space 64 (FIG. 3F).

Here, the second mask pattern 62 is formed on the AlGaN layer 63 which is the second nitride semiconductor thin film layer in which the first mask pattern 52 is not formed in the vertical extension direction.

Lastly, when the second mask pattern 62 is removed to form the empty space 64, AlGaN, which is the third nitride semiconductor thin film, is continuously laterally grown to form an AlGaN layer, which is a flat third nitride semiconductor thin film layer formed of coalescence ( Complete growth of 63) (FIG. 3G).

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

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

According to the present invention, the mask pattern formation, the nitride semiconductor side growth, and the mask pattern removal of FIGS. 3E to 3F described above are formed on the AlGaN layer 63, which is the second nitride semiconductor thin film layer formed of coalescence according to the lateral growth. By performing the planar nitride semiconductor growth completion process at least once more, it is possible to produce a nitride semiconductor substrate having a low defect density and reducing stress generation.

As described in detail above, in the present invention, when forming the III-V nitride semiconductor thin film layer by the lateral growth method, the growth is stopped during the lateral growth, the mask material is removed, and the lateral growth is performed to form the coalescence. By repeatedly performing the above, stresses, defects and inclinations occurring at the interface between the nitride film layer and the mask material, which are laterally grown, can be suppressed, and an empty space can be additionally reduced to reduce stress, and high light efficiency and There is an effect that can produce a device having excellent physical properties such as low leakage current.

Although the present 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 technical scope of the present invention, and such modifications and variations belong to the appended claims.

Claims (6)

Growing a first nitride semiconductor layer on top of the hetero substrate, and depositing a first mask pattern on the first nitride semiconductor layer; After the first step, the second nitride semiconductor is laterally grown, but before the coalescence of the second nitride semiconductor occurs on top of the first mask pattern, the growth of the second nitride semiconductor is stopped and the first mask pattern is wetted. A second step of etching; After the first mask pattern is etched, a third step of continuing to grow the second nitride semiconductor by side growth to grow a second nitride semiconductor layer having a flat surface formed of coalescence; Depositing a second mask pattern on the second nitride semiconductor layer on which the coalescence is formed; After the seventh step, the third nitride semiconductor is laterally grown, but before the coalescence of the third nitride semiconductor occurs on top of the second mask pattern, the growth of the third nitride semiconductor is stopped and the second mask pattern is wetted. A fifth step of etching; And a sixth step of growing the third nitride semiconductor layer having a flat surface formed of coalescence by continuously growing the third nitride semiconductor by etching the second mask pattern. Manufacturing method. The method of claim 1, And the second mask pattern is formed on the second nitride semiconductor thin film layer in which the first mask pattern is not formed in a vertical extension direction. The method according to claim 1 or 2, The method of manufacturing the nitride semiconductor substrate, characterized in that the process of the fourth to sixth step is continuously performed at least one or more times on top of the nitride semiconductor layer having a flat surface made of coalescing. The method of claim 1, 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 1 or 2, The thickness of the flat nitride semiconductor thin film layer constituting the coalescing is 3㎛ ~ 500㎛ manufacturing method of the nitride semiconductor substrate. The method of claim 4, wherein The composition of Al in the AlGaN thin film is a method of manufacturing a nitride semiconductor substrate, characterized in that 0≤Al≤0.3.