JP4587515B2 - Manufacturing method of semiconductor light emitting device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is related to a method of manufacturing a semiconductor light-emitting device.
[0002]
[Prior art]
A conventional semiconductor light emitting device is shown in FIGS. 4 is a cross-sectional view, FIG. 5 is a plan view, FIG. 6 is a cross-sectional view taken along the line AA ′ of FIG. 5, and FIG. 7 is a plan view showing an island-shaped semiconductor layer portion in an enlarged manner. In FIG. 4, 21 is a high-resistance silicon substrate, 22 is a one-conductivity-type semiconductor layer, 23 is a reverse-conductivity-type semiconductor layer, 24 is an individual electrode, and 25 is a common electrode.
[0003]
On the high-resistance silicon substrate 21, the one-conductivity-type semiconductor layer 22 and the reverse-conductivity-type semiconductor layer 23 are provided so that the reverse-conductivity-type semiconductor layer 23 has a smaller area than the one-conductivity-type semiconductor layer 22. A common electrode 25 is connected to the exposed portion of the semiconductor layer 22, and an individual electrode 24 is connected to the reverse conductivity type semiconductor layer 23. In FIG. 4, reference numeral 26 denotes a protective film made of a silicon nitride film or the like. In addition, as shown in FIG. 5, the common electrode 25 is provided in two groups so as to belong to different groups for each adjacent island-shaped one-conductivity-type semiconductor layer 22, and the adjacent island-shaped reverse electrode is provided. The conductive semiconductor layer 23 is connected to the same individual electrode 24.
[0004]
In such a light emitting diode array, each light emitting diode can selectively emit light by selecting a combination of the individual electrode 24 and the common electrode 25 and flowing a current.
[0005]
[Problems to be solved by the invention]
However, in this conventional semiconductor light emitting device, when the island-shaped semiconductor layers 22 and 23 are patterned into island shapes, the cross-section in the direction in which the island-shaped semiconductor layers 22 and 23 are aligned is shown in FIG. As shown, the lower end portion close to the high-resistance silicon substrate 21 is widened, and the lower end portion of the one-conductivity-type semiconductor layer 22 is wider than the upper end portion of the reverse-conductivity-type semiconductor layer 23.
[0006]
Therefore, the electrode wiring pattern 24 passing between the island-shaped semiconductors 22 and 23 and the adjacent island-shaped semiconductors 22 and 23 is caused by unstable reflection of irradiation light in the patterning exposure process, as shown in FIG. The shape of the edge of the wiring pattern 24 was found to be uneven. In other words, UV light is irradiated during exposure in the photolithographic process, but even if the photomask pattern is straight, if there is a step or roughness on the substrate side, the UV light is reflected and unevenness is likely to be formed at the edge of the formed wiring pattern. . The amount of light reflected by the wiring pattern 24 passing between the island-shaped semiconductor layers 22 and 23 and the adjacent island-shaped semiconductors 22 and 23 varies depending on the edge of the wiring pattern 24, and the optical print head is used. When used, there is a problem that a clear image cannot be obtained.
[0007]
The present invention has been made in view of the problems of such a conventional device. The island-shaped semiconductor layer is shaped so that the cross-section of the island-shaped semiconductor layer does not expand even at the lower end near the silicon substrate. An object of the present invention is to provide a method for manufacturing a semiconductor light-emitting device in which the shape of an edge of an electrode wiring pattern passing between the electrode-like semiconductor layers is improved and the amount of light reflected by the electrode wiring pattern does not vary. And
[0008]
[Means for Solving the Problems]
To achieve the above object, the manufacturing method of the semiconductor light emitting device according to the present invention, contrary to some of the island-shaped first conductivity type semiconductor layer and the one conductivity type semiconductor layer on the single crystal substrate is exposed provided by laminating the conductive semiconductor, provided by connecting the electrode and the one conductivity type semiconductor layer and the opposite conductivity type semiconductor layer, any of the adjacent one conductivity type semiconductor layer and the adjacent opposite conductivity type semiconductor layer as electrode of one semiconductor layer are connected to each other, in the manufacturing method of the semiconductor light emitting device Ru provided wiring for connecting the electrodes between the one semiconductor layer, when etching the between the one semiconductor layer The etching rate of the reverse conductivity type semiconductor layer is larger than the etching rate of the one conductivity type semiconductor layer, and the etching shape becomes a forward mesa due to the anisotropy of the one conductivity type semiconductor layer. semiconductor By anisotropic etching shape with reversed mesa and adjusting the composition ratio so anisotropy dominates the etch rate the opposite conductivity type semiconductor layer due to differences in, H _{2 SO} 4 _/ H 2 Using one of the etchants of O ₂ / H ₂ O system, HCl / H ₂ O ₂ / H ₂ O system, and HF / H ₂ O ₂ / H ₂ O system, the one semiconductor layer is aligned in cross-section, in the direction of the cross section the one semiconductor layer are arranged, characterized in that the lower end portion of the one conductivity type semiconductor layer is set to be narrower than the upper portion of the opposite conductivity type semiconductor layer.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
1 to 3 are views showing an embodiment of a semiconductor light emitting device according to the present invention. FIG. 1 shows a cross section of an island-shaped semiconductor layer in a direction intersecting with a direction in which the island-shaped semiconductor layers are arranged, and FIG. FIG. 3 shows a cross-sectional view of the island-shaped semiconductor layer in the direction in which the island-shaped semiconductor layers are arranged, and FIG. 1 to 3, 1 is a high-resistance silicon substrate, 2 is a one-conductivity-type semiconductor layer, 3 is a reverse-conductivity-type semiconductor layer, 4 is an individual electrode, and 5 is a common electrode.
[0010]
In the semiconductor light emitting device according to the present invention, a high-resistance single crystal silicon substrate with the {100} plane turned off by 2 to 7 ° in the [011] direction, a sapphire (Al ₂ O ₃ ) C-plane substrate, or the like is preferably used. .
[0011]
The one conductivity type semiconductor layer 2 includes a buffer layer 2a, an ohmic contact layer 2b, and an electron injection layer 2c. The buffer layer 2a is formed to a thickness of about 2 to 4 μm, the ohmic contact layer 2b is formed to a thickness of about 0.1 to 1.0 μm, and the electron injection layer 2c is formed to a thickness of about 0.2 to 0.4 μm. It is formed. The buffer layer 2a and the ohmic contact layer 2b are formed of gallium arsenide or the like, and the electron injection layer 2c is formed of aluminum gallium arsenide or the like. The ohmic contact layer 2b contains about 1 × 10 ¹⁶ to 1 × 10 ¹⁹ atoms / cm ³ of one conductivity type semiconductor impurity such as silicon, and the electron injection layer 2c also contains one conductivity type semiconductor impurity such as silicon of 1 × 10 ^16. ˜1 × 10 ¹⁹ atoms / cm ^{3 is} contained. The buffer layer 2a is provided to prevent misfit dislocation based on mismatch of lattice constant between the high-resistance silicon substrate 1 and the semiconductor layer, and does not need to contain semiconductor impurities.
[0012]
The reverse conductivity type semiconductor layer 3 includes a light emitting layer 3a, a clad layer 3b, and a second ohmic contact layer 3c. The light emitting layer 3a and the clad layer 3b are formed to a thickness of about 0.2 to 4 μm, and the second ohmic contact layer 3c is formed to a thickness of about 0.01 to 1 μm. The light emitting layer 3a and the cladding layer 3b are made of aluminum gallium arsenide or the like, and the second ohmic contact layer 3c is made of gallium arsenide or the like.
[0013]
The light emitting layer 3a and the clad layer 3b have different mixed crystal ratios of aluminum arsenide (AlAs) and gallium arsenide (GaAs) in consideration of the electron confinement effect and the light extraction effect. The light emitting layer 3a and the clad layer 3b contain about 1 × 10 ¹⁶ to 1 × 10 ²¹ atoms / cm ³ of a reverse conductivity type semiconductor impurity such as zinc (Zn), and the second ohmic contact layer 3c is a reverse conductivity such as zinc. A type semiconductor impurity of about 1 × 10 ¹⁹ to 1 × 10 ²¹ atoms / cm ^{3 is} contained.
[0014]
The insulating film 6 is made of silicon nitride or the like and has a thickness of about 3000 mm. The individual electrode 4 and the common electrode 5 are made of gold / chromium (Au / Cr) or the like and are formed with a thickness of about 1 μm.
[0015]
Also in the semiconductor light emitting device of the present invention, as shown in the conventional example of FIG. 5, island-like semiconductor layers 2 (22), 3 (1) composed of a one-conductivity-type semiconductor layer 2 (22) and a reverse-conductivity-type semiconductor layer 3 (23). 23) are arranged in a line on the substrate 1 (21) and connected to the same individual electrode 4 (24) for each adjacent island-like semiconductor layer 2 (22), 3 (23), and the same individual electrode 4 (24). The lower one conductive type semiconductor layer 2 (22) connected to is connected in a plurality of groups so as to be connected to different common electrodes 5 (25). By selecting the individual electrode 4 (24) and passing a current, it is used as an exposure light source for a photosensitive drum for a page printer.
[0016]
FIG. 2 shows a cross section in the direction in which island-like semiconductor layers are arranged in the semiconductor light emitting device according to the present invention. In general, wet etching of gallium arsenide uses a liquid in which H ₂ SO ₄ (98%) / H ₂ O ₂ (30%) / H ₂ O is mixed at an appropriate ratio, and by anisotropic etching, { It is known to obtain a forward mesa shape in the [110] direction and an inverted mesa shape in the [1-10] direction by etching of the 100} plane, but when aluminum gallium arsenide is laminated on the gallium arsenide, Since the etching rate of aluminum gallium arsenide is larger than that of gallium arsenide, the reverse mesa shape in the aluminum gallium arsenide layer is dominant, and the underlying gallium arsenide does not necessarily have the reverse mesa shape. Therefore, the shape shown in FIG. 6 is obtained depending on the liquid composition, but in the direction in which the island-shaped semiconductor layers are arranged depending on the H ₂ O ₂ ratio in the H ₂ SO ₄ / H ₂ O ₂ / H ₂ O of the etching liquid. The cross-sectional shape of the island-like semiconductor layer can be changed.
[0017]
For example, when the upper layer is aluminum (0.3) gallium (0.7) arsenic, H ₂ O ₂ (30 wt%) 50% by volume (H ₂ O ₂ alone 15% by volume) and the reverse conductivity type semiconductor layer 3 and the lower end of the one-conductivity type semiconductor layer 2 are substantially perpendicular to the substrate 1. When this H ₂ O ₂ ratio is reduced, the lower end of the one-conductivity-type semiconductor layer 2 becomes wider than the upper end of the reverse-conductivity-type semiconductor layer 3, and as shown in FIG. 6, has a long tail near the substrate 1 (11). However, when the H ₂ O ₂ ratio is increased, the lower end portion of the one-conductivity-type semiconductor layer 2 may be narrower than the upper end portion of the reverse-conductivity-type semiconductor layer 3 to be inside as shown in FIG. it can.
[0018]
As another method of narrowing the lower end portion of the one-conductivity-type semiconductor layer 2 than the upper end portion of the reverse-conductivity-type semiconductor layer 3, in the case of the same amount of H ₂ O ₂ ratio, the H ₂ SO ₄ ratio is increased. However, the bottom end of the one-conductivity-type semiconductor layer 2 can be suppressed .
[0019]
Thus, if the lower end portion of the one-conductivity-type semiconductor layer 2 is narrower than the upper end portion of the reverse-conductivity-type semiconductor layer 3 and becomes the inner side, the island-like semiconductor layers 2 and 3 adjacent to the island-like semiconductor layers 2 and 3 are formed in the subsequent electrode formation process. With respect to the wiring pattern 4 passing between the semiconductor layers 2 and 3, irregular reflection of light at the time of exposure can be suppressed, and a good pattern can be formed. In the semiconductor light emitting device thus completed, the amount of light reflected by the electrode wiring pattern 4 passing between the island-like semiconductor layers 2 and 3 and the adjacent island-like semiconductor layers 2 and 3 can be made uniform. .
[0020]
The etching solution to be used is not limited to the H ₂ SO ₄ / H ₂ O ₂ / H ₂ O system, and in the case of acid, HCl (aq), HF (aq), or the like may be used instead of H ₂ SO ₄ .
[0021]
In the above-described embodiment, the example in which the individual electrode 4 passes between the island-shaped semiconductor layers 2 and 3 has been described. However, the same operation and effect can be obtained when the common electrode 5 passes between the island-shaped semiconductor layers 2 and 3. It is done.
[0022]
Next, a method for manufacturing the semiconductor light emitting device as described above will be described. First, a one-conductivity-type semiconductor layer 2 and a reverse-conductivity-type semiconductor layer 3 are sequentially stacked on a high-resistance silicon single crystal substrate 1 by MOCVD or the like.
[0023]
In this case, as source gases, TMG ((CH ₃ ) ₃ Ga), TEG ((C ₂ H ₅ ) ₃ Ga), arsine (AsH ₃ ), TMA ((CH ₃ ) ₃ Al), TEA ((C ₂ H ₅ ) ₃ Al) or the like is used, and silane (SiH ₄ ), hydrogen selenide (H ₂ Se), DMZ ((CH ₃ ) ₂ Zn) or the like is used as the gas for controlling the conductivity type. As the carrier gas, H ₂ or the like is used.
[0024]
Next, the semiconductor layers 2 and 3 are patterned in an island shape so that adjacent elements are electrically separated. At that time, for example, a liquid having a large H ₂ O ₂ ratio of H ₂ SO ₄ / H ₂ O ₂ / H ₂ O is used, and the lower end of the one-conductivity-type semiconductor layer 2 is narrower than the upper end of the reverse-conductivity-type semiconductor layer 3. To be.
[0025]
Next, a part on one end side of the one conductivity type semiconductor layer 2 is exposed, and an upper end portion of the reverse conductivity type semiconductor layer 3 is formed wider than a lower end portion of the one conductivity type semiconductor layer 2. The one conductivity type semiconductor layer 2 and the opposite conductivity type semiconductor layer 3 are etched. This etching is also performed by, for example, or performed or carried out by c or falling edge of bets etching with _{H 2 SO 4 / H 2 O} 2 / H 2 O system liquid, by dry etching using _CCl 2 _{F 2} gas.
[0026]
Next, an insulating film 6 made of silicon nitride is formed and patterned by plasma CVD using silane gas (SiH ₄ ) and ammonia gas (NH ₃ ). Finally, chromium and gold are formed by vapor deposition or sputtering and patterned.
[0027]
【The invention's effect】
As described above, according to the semiconductor light emitting device of the present invention, the lower end portion of the one conductivity type semiconductor layer is narrower than the upper end portion of the reverse conductivity type semiconductor layer in the cross section in the direction in which the island-shaped semiconductor layers are arranged. Therefore, an electrode wiring pattern passing between the island-shaped semiconductor layer and the adjacent island-shaped semiconductor layer can be formed in an accurate shape, and thus an electrode wiring pattern passing between the island-shaped semiconductor layer and the adjacent island-shaped semiconductor layer Variations in the amount of reflected light can be reduced as much as possible, and when used in an optical print head, a clear image can be obtained.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view in a direction crossing an arrangement direction of island-shaped semiconductor layers showing an embodiment of a semiconductor light emitting device according to the present invention.
FIG. 2 is a cross-sectional view in the arrangement direction of island-like semiconductor layers of a semiconductor light emitting device according to the present invention.
FIG. 3 is an enlarged plan view of an island-shaped semiconductor layer portion of the semiconductor light emitting device according to the present invention.
FIG. 4 is a cross-sectional view in a direction intersecting with an arrangement direction of island-shaped semiconductor layers of a conventional semiconductor light emitting device.
FIG. 5 is a plan view showing a conventional semiconductor light emitting device.
FIG. 6 is a cross-sectional view of a conventional semiconductor light emitting device in an array of island-shaped semiconductor layers.
FIG. 7 is an enlarged plan view showing an island-shaped semiconductor layer portion of a conventional semiconductor light emitting device.
[Explanation of symbols]
1: substrate, 2: one conductivity type semiconductor layer, 3: reverse conductivity type semiconductor layer, 4: individual electrode, 5: common electrode wiring, 6: insulating film

Claims (2)

Provided by laminating the opposite conductivity type semiconductor so as to partially expose the island-shaped first conductivity type semiconductor layer and the one conductivity type semiconductor layer on a single crystal substrate, wherein said one conductivity type semiconductor layer reverse-conducting provided by connecting the electrodes to the type semiconductor layer, such that the electrodes of one of the semiconductor layers of the adjacent one conductivity type semiconductor layer and adjacent the opposite conductivity type semiconductor layer are connected to each other, of the one semiconductor layer the method of manufacturing a semiconductor light emitting device Ru provided wiring for connecting the electrodes between,
When etching between the one semiconductor layer, the etch rate of the reverse conductivity type semiconductor layer is larger than the etching rate of the one conductivity type semiconductor layer, and the anisotropy of the one conductivity type semiconductor layer The etching shape becomes a forward mesa, the etching shape becomes a reverse mesa due to the anisotropy of the reverse conductivity type semiconductor layer, and the anisotropy of the reverse conductivity type semiconductor layer becomes dominant due to the difference in the etching rate. One of H ₂ SO ₄ / H ₂ O ₂ / H ₂ O system, HCl / H ₂ O ₂ / H ₂ O system, and HF / H ₂ O ₂ / H ₂ O system, with the composition ratio adjusted to Using an etchant,
In the direction of the cross section the one semiconductor layer are aligned, a method of manufacturing a semiconductor light emitting device characterized by the lower end portion of the one conductivity type semiconductor layer is set to be narrower than the upper portion of the opposite conductivity type semiconductor layer . 2. The method of manufacturing a semiconductor light emitting device according to claim 1, wherein a part of the one conductivity type semiconductor layer and a part of the reverse conductivity type semiconductor layer are formed of an aluminum gallium arsenide layer.

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