JPH09213993A - Led array manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an efficient manufacturing method of a led array having superior characteristics in a simple process by forming an electrode pattern of the array, irrespective of the etching margin etc. SOLUTION: A diffusion mask (of an AlN thin film) 12 having openings for selectively diffusing Zn is formed on an n-type compsn. semiconductor substrate 11, Zn is diffused through the mask openings 12 into the substrate 11, the semiconductor surface at a part of the diffused region is exposed, a lift-off negative resist is applied to the entire surface of the substrate and patterned to form a p-electrode pattern contg. Al as a main material, a metal thin film 23 contg. Al as a main material is formed on the entire surface, and the p- electrode pattern 23A is formed by the lift off method and n-electrodes are formed on the back face of the substrate.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an LED array used in an LED printer head.

[0002]

2. Description of the Related Art Conventionally, a method for manufacturing such an LED array is disclosed in, for example, Document 1 "Solid-state light emitting device and its application by Tetsuro Nakamura and Kiyoshi Uchimaru".
Generally, in forming a pn junction for manufacturing an LED array, an impurity is selectively diffused into a substrate by using an insulating film (diffusion mask) having an opening on a region to be diffused on a semiconductor substrate. In this selective diffusion, it is the most general to diffuse Zn, which is a p-type impurity, into the n-type compound semiconductor substrate because of the ease of forming a contact electrode in the selective diffusion region.

In the Zn selective diffusion step, an Al ₂ O ₃ film or Al is used as a diffusion mask in order to obtain a favorable diffusion shape.
A technique using an N film has also been proposed (for example, Japanese Patent Application No. 07-6139 relating to the invention of the present applicant). For example, in vapor phase diffusion, as shown in FIG. 4, a diffusion mask 2 is patterned on a substrate 1 and diffusion is performed with a film structure in which a protective film 3 is formed thereon.

In solid phase diffusion, as shown in FIG. 5, a diffusion mask 2 is patterned on a substrate 1, and a diffusion source film 4 and an anneal cap film 5 are formed on the diffusion mask 2 to form a diffusion structure. I do. In either case, the diffusion shape and the diffusion depth can be controlled extremely stably, and as a result, it is possible to manufacture an LED array with small variations.

For example, as a structure of the interlayer insulating film, as shown in FIG.
A technique has been proposed in which the insulating film 6 is provided and a two-layer laminated film is used as an interlayer insulating film. However, one diffusion mask is used as an interlayer insulating film, and an electrode pattern having Al as a main material is formed on the diffusion mask. Can also be formed. In addition, 7
Is a diffusion region, 8 is a p-electrode pattern, and 9 is an n-electrode.

By the way, in the electrode pattern forming step, conventionally, hot phosphoric acid was used to etch a thin film containing Al as a main material to form an electrode pattern. Al ₂ O ₃ and AlN can be etched by hot phosphoric acid, but 5
Al ₂ O ₃ or Al for hot phosphoric acid at 0 ° C
Since the etching rate of N is considerably slowed, even if the electrode pattern is over-etched, it is possible to considerably prevent Al ₂ O ₃ or AlN in the portion without the electrode film from being etched.

Therefore, in forming the electrode pattern, the LED array has been manufactured by using hot phosphoric acid at about 50.degree.
The LED array thus manufactured had excellent characteristics in terms of light emission characteristics and electric characteristics.

[0008]

However, although the above-mentioned conventional LED array has excellent characteristics in light emission characteristics and electric characteristics, even if hot phosphoric acid at about 50 ° C. is used, Al ₂ O ₃ or AlN film cannot completely prevent the etching at the time of forming the electrode pattern, so in this process, even if there is no problem in characteristics if excessive over-etching is performed, the part without the electrode pattern is etched. Therefore, there is a fear that the appearance may be deteriorated.

Further, when the etching for forming the Al electrode pattern is performed with hot phosphoric acid, the side surface of Al is etched and the size is reduced. When the etching for forming the electrode pattern is performed over the entire surface of the semiconductor wafer, the etching rate is not always uniform over the entire surface of the wafer, and therefore overetching may be partially performed.

At such an over-etched portion, the electrode pattern is side-etched to that extent, and the size is reduced. In such a case, if the electrode pattern width is narrow, there is a possibility of disconnection, and there is also a possibility of an increase in current density due to the reduction in size. The present invention eliminates the above-mentioned problems, and in the formation of the electrode pattern of the LED array, the electrode pattern is formed irrespective of the etching margin and the like, and the LED array is excellent in efficiency and characteristics in a simple process. It aims at providing the manufacturing method of.

[0011]

In order to achieve the above object, the present invention provides: (1) In a method of manufacturing an LED array, a diffusion mask having an opening for selectively diffusing Zn in an n-type compound semiconductor substrate. , A step of diffusing Zn into the semiconductor substrate through the diffusion mask opening, a step of exposing a semiconductor surface of a partial region of the diffusion region, a resist is applied to the entire surface of the semiconductor substrate, and Al is mainly formed. The step of patterning this resist to form a p-electrode pattern as a material, the step of forming an electrode film on the entire surface, the step of forming a p-electrode pattern by a lift-off method, and the n-electrode on the back surface of the semiconductor substrate. And the step of forming.

As described above, since the p-electrode pattern is formed by the lift-off method, it is possible to avoid the formation of the p-electrode pattern by using hot phosphoric acid.
It is possible to completely prevent the electrode pattern from being etched. Therefore, it is not necessary to consider the margin of etching or dimensional change in the electrode pattern forming step, variation in finish is eliminated, and an LED array having better characteristics can be manufactured.

Further, in addition to these effects, an extreme over-etching phenomenon does not occur even in the unlikely event of an accident, so that the labor of the process as a whole can be saved. (2) In the method of manufacturing an LED array described in (1) above, a thin film made of a material that can be etched with hot phosphoric acid is used as the diffusion mask, and the diffusion mask is used as an interlayer insulating film. The p-electrode pattern is formed on the top.

Therefore, in addition to the effect of the invention described in (1) above, L which is efficient and has excellent characteristics in a simple process.
ED arrays can be manufactured. (3) In the method of manufacturing an LED array described in (1) or (2) above, another interlayer insulating film is formed on the diffusion mask, and the interlayer insulating film is a material that can be etched by hot phosphoric acid. Is a thin film.

Therefore, the effects of the invention described in (1) or (2) above can be obtained, and an LED array having a multilayer insulating film can be easily manufactured. (4) In the method for manufacturing an LED array described in (2) or (3) above, the material that can be etched with hot phosphoric acid is Al.
It is an N film or an Al ₂ O ₃ film.

[0016] Thus, by a lift-off method in the step of forming the electrode pattern of Al as a main material on the AlN film or Al ₂ O ₃ film, it is possible to perform the electrode pattern formation, is AlN film or the Al ₂ O ₃ film It is possible to completely prevent these thin films from being etched even in the presence of exposed areas. Further, since no etching liquid is used, it is possible to completely prevent Al and etching pattern dimension change.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. First, a method for manufacturing an LED array before the electrode pattern forming step of the present invention will be described. Here, an example of forming a pn junction array by solid-phase diffusing Zn into an n-type compound semiconductor substrate will be described.

FIG. 1 is a sectional view of the manufacturing process of the LED array of the present invention. First, as shown in FIG. 1A, an AlN thin film 12 is deposited on an n-type compound semiconductor substrate 11, for example, a GaAs _1-X P _X substrate by a sputtering method, and a standard photolithography method is used. A diffusion mask opening 13 is formed in the diffusion planned area.

Next, as shown in FIG. 1 (b), a mixed thin film of ZnO and SiO ₂ is applied as a diffusion source thin film 14,
Further, the AlN thin film 15 is applied as an annealing cap. Next, as shown in FIG. 1C, the substrate in this state is heated at, for example, 700 ° C. to diffuse Zn into the substrate region of the diffusion mask opening 13 to form the diffusion region 16.

Next, as shown in FIG. 1D, a p electrode pattern (metal thin film pattern) 23A is formed on the substrate on which Zn is selectively diffused. After that, sintering is performed at about 500 ° C. to form an ohmic contact. Then, the back surface of the substrate is polished, Au alloy is applied as a film for the n-electrode 17, and sintered to complete the LED array. Next, a method of manufacturing the electrodes of the LED array showing the embodiment of the present invention will be described.

FIG. 2 is a sectional view (No. 1) of an electrode manufacturing process of an LED array showing an embodiment of the present invention, and FIG. 3 is a sectional view (No. 2) of an electrode manufacturing process of the LED array. First, as shown in FIG. 2A, as described above, the AlN diffusion mask (AlN thin film) 12 is formed on the n-type compound semiconductor substrate 11.
And the diffusion mask opening 13 is formed in the planned diffusion region. Using the AlN diffusion mask 12, Z
Diffusion region 16 is formed by performing n-selective solid phase diffusion, and the substrate surface is exposed at diffusion mask opening 13.

Next, as shown in FIG. 2B, a negative lift-off resist 21 is applied. Next, FIG.
As shown in FIG. 3, after soft baking, exposure and development are performed using a photomask having a positive electrode pattern. Here, the film thickness of the negative resist 21 is made thicker than the expected film thickness of the electrode thin film. This is for facilitating the melting of the negative resist 21 described later and smoothly performing the lift-off.

Next, FIGS. 3 (a-1) and 3 (a-
As shown in 2), the negative resist pattern 21A can be formed in a region other than the electrode pattern formation scheduled region 22. Next, as shown in FIG. 3B, a metal thin film 23 containing Al as a main material is formed on the entire surface.

After that, as shown in FIG. 3C, the negative resist pattern 21A is melted using, for example, acetone or a solvent suitable for the resist used. Then, the metal thin film 23 on the negative resist pattern 21A is removed, and the p electrode pattern 23A can be formed. As described above in detail, the Al electrode pattern is formed without using hot phosphoric acid.
The 1N thin film is not etched at all.

Furthermore, since hot phosphoric acid is not used, Al
The electrode thin film itself made of is not etched either, and dimensional changes due to overetching can be completely prevented. In the above embodiment, Al ₂ example has been described for implementing the Zn selective solid-phase diffusion using diffusion mask film an AlN film, for example, that can be satisfactorily controlled diffusion shape
By vapor phase diffusion using the O ₃ film as a diffusion mask, Z
The present invention can be applied even when n is selectively diffused. That is, since the Al ₂ O ₃ film has a property to be etched in hot phosphoric acid, the use of hot phosphoric acid when forming the Al electrode pattern Al ₂ O ₃ thin film after diffusion, more or less Al ₂ O ₃ There is a possibility that the thin film will be etched, but it can be completely prevented by applying the present invention.

Further, from the gist of the present invention, when the diffusion mask or the interlayer insulating film directly below the Al electrode when the interlayer insulating film is provided by using the laminated film is made of a material other than AlN and Al ₂ O ₃ described above, Even when a material that is etched with hot phosphoric acid is used, the same effect can be obtained by applying the manufacturing method of the present invention. Further, in the above embodiment, mainly on the Al ₂ O ₃ or AlN thin film which is the diffusion mask film,
The case of forming an electrode pattern using Al as a main material has been described. However, even when an interlayer insulating film is formed on a diffusion mask using a material such as a SiN film that is not etched by hot phosphoric acid, Al ₂ O is used for forming an electrode. ₃ or AlN
The present invention can be applied even when there is a portion where the thin film is exposed.

It should be noted that the present invention is not limited to the above embodiment, and various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

[0028]

As described above, according to the present invention, the following effects can be obtained. (1) According to the invention of claim 1, in the method of manufacturing an LED array, the p-electrode pattern is formed by the lift-off method. Therefore, it is possible to avoid the formation of the p-electrode pattern by using hot phosphoric acid. Therefore, it is possible to completely prevent the p electrode pattern from being etched.

Therefore, in the electrode pattern forming step, it is not necessary to consider the margin of etching or dimensional change, variation in finish is eliminated, and L having better characteristics is obtained.
ED arrays can be manufactured. Further, in addition to these effects, the extreme over-etching phenomenon does not occur even in the event of an accident, so that the labor of the process as a whole can be saved.

(2) According to the second aspect of the present invention, a thin film made of a material that can be etched with hot phosphoric acid is used as the diffusion mask, and the diffusion mask is used as an interlayer insulating film. Since the p-electrode pattern is formed on the LED array, in addition to the effect of the invention described in (1) above, it is possible to manufacture an LED array that is efficient and has excellent characteristics in a simple process.

(3) According to the invention described in claim 3, the effect of the invention described in (1) or (2) above can be obtained, and an LED array having a multi-layer insulating film formed thereon can be easily manufactured. can do. (4) According to the invention described in claim 4, since the AlN film or the Al ₂ O ₃ film is used as the material that can be etched with hot phosphoric acid, Al is deposited on the AlN film or the Al ₂ O ₃ film. The electrode pattern can be formed by the lift-off method in the step of forming the electrode pattern using the main material. Further, even if there is a region where the AlN film or the Al ₂ O ₃ film is exposed, it is possible to completely prevent these thin films from being etched.

Further, since no etching liquid is used, Al and etching pattern dimension change can be completely prevented.

[Brief description of drawings]

FIG. 1 is a sectional view of a manufacturing process of an LED array of the present invention.

FIG. 2 is a sectional view (No. 1) of an electrode manufacturing process of the LED array showing the embodiment of the present invention.

FIG. 3 is a sectional view (No. 2) of the electrode manufacturing process of the LED array showing the embodiment of the present invention.

FIG. 4 is an explanatory diagram of a conventional LED array by vapor phase diffusion in a diffusion region.

FIG. 5 is an explanatory diagram of a conventional LED array by solid phase diffusion in a diffusion region.

FIG. 6 is an explanatory diagram of an LED array using a conventional two-layer laminated film as an interlayer insulating film.

[Explanation of symbols]

11 n-type compound semiconductor substrate (GaAs _1-X P _X substrate) 12, 15 AlN thin film (diffusion mask) 13 diffusion mask opening 14 diffusion source thin film 16 diffusion region 17 n electrode 21 negative resist 22 electrode pattern formation region 21A Negative resist pattern 23 Metal thin film mainly made of Al 23A p electrode pattern (metal thin film pattern)

Claims (4)

[Claims] 1. A process of: (a) forming a diffusion mask having an opening for selectively diffusing Zn in an n-type compound semiconductor substrate; and (b) diffusing Zn into the semiconductor substrate through the diffusion mask opening. And (c) exposing a semiconductor surface in a partial region of the diffusion region, and (d) applying a resist to the entire surface of the semiconductor substrate to form a p-electrode pattern containing Al as a main material. Patterning, (e) forming an electrode film on the entire surface,
A method of manufacturing an LED array, comprising: (f) forming a p-electrode pattern by a lift-off method; and (g) forming an n-electrode on the back surface of the semiconductor substrate. 2. The method for manufacturing an LED array according to claim 1, wherein a thin film made of a material that can be etched with hot phosphoric acid is used as the diffusion mask, and the diffusion mask is used as an interlayer insulating film. A method for manufacturing an LED array, which comprises forming a p-electrode pattern on a film. 3. The method of manufacturing an LED array according to claim 1, wherein another interlayer insulating film is formed on the diffusion mask, and the interlayer insulating film is made of a material that can be etched by hot phosphoric acid. L, which is a thin film
Manufacturing method of ED array. 4. The method of manufacturing an LED array according to claim 2, wherein the material that can be etched with hot phosphoric acid is A.
LE characterized by being an IN film or an Al ₂ O ₃ film
Method for manufacturing D array.