JP3231613B2 - LED array manufacturing method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a method for manufacturing an LED array used for an LED printer head.

[0002]

2. Description of the Related Art Conventionally, a method for manufacturing such an LED array is disclosed, for example, in Document 1 "Tetsuro Nakamura and Kiyoshi Uchimaru", "Solid State Light Emitting Elements and Their Applications".

Generally, in forming a pn junction for manufacturing an LED array, a pn junction is formed on a diffusion region on a semiconductor substrate.
Using an insulating film (diffusion mask) having an opening, impurities are selectively diffused into the substrate. In this selective diffusion, Zn, which is a p-type impurity, is most commonly diffused into an n-type compound semiconductor substrate because of easy formation of a contact electrode in a selective diffusion region.

In a Zn selective diffusion step, an Al ₂ O ₃ film or an Al
A technique using an N film has also been proposed (for example, Japanese Patent Application No. 07-6139 according to the invention of the present applicant).

For example, in the gas phase diffusion, as shown in FIG. 4, a diffusion mask 2 is patterned on a substrate 1 and diffusion is performed in a film structure in which a protective film 3 is formed thereon.

In the 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 annealing cap film 5 are formed thereon. I do.

In any case, the diffusion shape and the diffusion depth can be controlled extremely stably, and as a result, an LED array with small variation can be manufactured.

For example, as shown in FIG. 6, the structure of the interlayer insulating film is
A technique has been proposed in which an insulating film 6 is provided and a two-layer laminated film is used as an interlayer insulating film. However, an electrode pattern using Al as a main material on a diffusion mask using one diffusion mask as an interlayer insulating film has been proposed. It is also possible to form Note that 7
Denotes a diffusion region, 8 denotes a p-electrode pattern, and 9 denotes an n-electrode.

By the way, in the electrode pattern forming step, an electrode pattern is conventionally formed by etching a thin film mainly composed of Al using hot phosphoric acid. Al ₂ O ₃ and AlN can be etched by hot phosphoric acid.
Al ₂ O ₃ or Al for hot phosphoric acid at about 0 ° C
Since the etching rate of N becomes considerably slow, even if overetching is performed by electrode pattern etching, etching of Al ₂ O ₃ or AlN in a portion where there is no electrode film can be considerably prevented.

Therefore, in forming an electrode pattern, an LED array has been manufactured using hot phosphoric acid at about 50 ° C.
The LED array manufactured in this way had excellent characteristics in light emission characteristics and electrical characteristics.

[0011]

However, the above-mentioned conventional LED array has excellent characteristics in terms of light-emitting characteristics and electric characteristics, but even if hot phosphoric acid at about 50 ° C. is used, Al ₂ O 3 ₃ or the AlN film cannot completely prevent the etching during the formation of the electrode pattern. Therefore, in this step, the portion without the electrode pattern is etched even if there is no problem in characteristics if the over-etching is performed extremely. There is a risk that the appearance will be worsened.

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 etching for forming an electrode pattern is performed over the entire surface of a semiconductor wafer, the etching rate is not always uniform over the entire surface of the wafer, so that overetching may occur partially.

In such an over-etched portion, the electrode pattern is side-etched to a greater extent, and its size is reduced. In such a case, if the width of the electrode pattern is small, there is a possibility of disconnection, and a decrease in size may increase current density.

The present invention eliminates the above-mentioned problems and provides an LE
It is an object of the present invention to provide a method for manufacturing an LED array in which an electrode pattern is formed irrespective of an etching margin or the like in the formation of an electrode pattern of a D array, and which is easy and efficient and has excellent characteristics.

[0016]

According to the present invention, there is provided a method of manufacturing an LED array, comprising the steps of: (a) providing an n-type compound semiconductor substrate with an opening for selectively diffusing Zn ;
Both are materials that can be etched with hot phosphoric acid
Forming a diffusion mask made of an AlN film or an Al ₂ O ₃ film , diffusing Zn into the semiconductor substrate through the diffusion mask opening, and exposing a semiconductor surface in a partial region of the diffusion region; A step of applying a resist over the entire surface of the semiconductor substrate and patterning the resist to form a p-electrode pattern mainly composed of Al; a step of forming an electrode film over the entire surface; and forming a p-electrode pattern by a lift-off method And forming an n-electrode on the back surface of the semiconductor substrate.

As described above, since the p-electrode pattern is formed by the lift-off method, the formation of the p-electrode pattern by using hot phosphoric acid can be avoided.
The electrode pattern can be completely prevented from being etched.

Therefore, in the electrode pattern forming step, it is not necessary to consider the margin of the etching and the dimensional change.
An ED array can be manufactured.

Further, in addition to these effects, since an extreme over-etching phenomenon does not occur even in the event of an accident, it is possible to save labor as a whole.

In particular, materials that can be etched with hot phosphoric acid
Since an AlN film or an Al ₂ O ₃ film is used, an electrode pattern is formed by a lift-off method in a step of forming an electrode pattern mainly composed of Al on the AlN film or the Al ₂ O ₃ film. Therefore , even when there is a region where the AlN film or the Al ₂ O ₃ film is exposed, it is possible to completely prevent the etching of these thin films.

Further, since no etching solution is used, a change in dimension of Al and the etching pattern can be completely prevented.

[0022] (2) In the manufacturing method of the above (1) Symbol placement of the LED array, wherein to form another layer of the interlayer insulating film on a diffusion mask, etchable material interlayer insulating film to heat phosphoric acid And a thin film made of an AlN film or an Al ₂ O ₃ film .

[0023] Thus, it is possible to achieve the effect of the invention described in (1) Symbol mounting, the LED array multilayered insulating film is formed can be easily manufactured.

[0024]

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 in which Zn is solid-phase diffused into an n-type compound semiconductor substrate to produce a pn junction array will be described.

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

First, as shown in FIG. 1 (a), n-type compound semiconductor substrate 11, for example, the GaAs _1-X P X substrate, attach film AlN thin film 12 by sputtering, standard photolithographic The diffusion mask opening 13 is formed in the region to be diffused by the method described above.

Next, as shown in FIG. 1B, a mixed thin film of ZnO and SiO ₂ is formed as the diffusion source thin film 14.
Further, an 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 a diffusion region 16. I do.

Next, as shown in FIG. 1D, a p-electrode pattern (metal thin film pattern) 23A is formed on the substrate in which Zn is selectively diffused. Thereafter, sintering is performed at about 500 ° C. to form an ohmic contact. Thereafter, the back surface of the substrate is polished, a film of an Au alloy is formed as the n-electrode 17, and sintering is completed to complete the LED array.

Next, a method of manufacturing an electrode of an LED array according to an embodiment of the present invention will be described.

FIG. 2 is a sectional view (part 1) of an LED array electrode manufacturing process showing an embodiment of the present invention, and FIG. 3 is a sectional view (part 2) of an LED array electrode manufacturing step.

First, as shown in FIG. 2A, as described above, an AlN diffusion mask (AlN thin film) 12 is formed on an n-type compound semiconductor substrate 11, and a diffusion mask opening 13 is formed in a diffusion expected region. Is formed. Using the AlN diffusion mask 12, Zn selective solid phase diffusion is performed to form a diffusion region 16, and the substrate surface is exposed at the diffusion mask opening 13.

Next, as shown in FIG. 2B, a negative resist 21 for lift-off is applied.

Next, as shown in FIG. 2C, 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 larger than the expected film thickness of the electrode thin film.
This facilitates dissolution of a negative resist 21 described later,
This is for smooth lifting 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 region 22.

Next, as shown in FIG. 3B, a metal thin film 23 mainly composed of Al is formed on the entire surface.

Thereafter, as shown in FIG. 3C, the negative resist pattern 21A is dissolved using, for example, acetone or a solvent suitable for the resist to be 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, since the Al electrode pattern is formed without using hot phosphoric acid, the AlN thin film is not etched at all.

Further, since hot phosphoric acid is not used, Al
The electrode thin film itself mainly composed of is not etched, and the dimensional change due to over-etching can be completely prevented.

[0042] 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 it can be satisfactorily controlled diffusion shape
By gas phase diffusion using an 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 is etched, but this can be completely prevented by applying the present invention.

Further, from the gist of the present invention, when the interlayer insulating film immediately below the Al electrode when the interlayer insulating film is provided by using the diffusion mask or the laminated film, even if the material other than AlN and Al ₂ O ₃ is used, The same effect can be obtained by applying the manufacturing method of the present invention even when a material etched with hot phosphoric acid is used.

Further, in the above-described embodiment, the case where the electrode pattern mainly composed of Al is formed on the Al ₂ O ₃ or AlN thin film which is the diffusion mask film has been described, but the SiN film or the like is formed on the diffusion mask. The present invention can be applied to a case where an interlayer insulating film is provided using a material which is not etched by hot phosphoric acid, and a case where an Al ₂ O ₃ or AlN thin film is exposed in electrode formation.

It should be noted that the present invention is not limited to the above-described 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.

[0046]

As described above, according to the present invention, the following effects can be obtained.

(1) According to the first aspect of the present invention, the LE
In the method of manufacturing the D array, the p-electrode pattern is formed by the lift-off method, so that the formation of the p-electrode pattern by using hot phosphoric acid can be avoided, and the p-electrode pattern is completely etched. Can be prevented.

Therefore, in the electrode pattern forming step, it is not necessary to consider the margin of the etching and the dimensional change.
An ED array can be manufactured.

Further, in addition to these effects, since an extreme over-etching phenomenon does not occur even in the case of an accident, labor saving of the process is possible as a whole.

In particular, A is formed on the AlN film or the Al ₂ O ₃ film.
An electrode pattern can be formed by a lift-off method in a step of forming an electrode pattern having l as a main material.
Further, even when there is a region where the AlN film or the Al ₂ O ₃ film is exposed, it is possible to completely prevent the etching of these thin films.

Further, since no etching solution is used, a change in the dimensions of both Al and the etching pattern can be completely prevented.

[0052] (2) According to the second aspect of the present invention, it is possible to achieve the effect of the invention described in (1) Symbol placement, that the easily manufactured LED array multilayered insulating film is formed it can.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a manufacturing process of an LED array according to the present invention.

FIG. 2 is a sectional view (part 1) of an LED array electrode manufacturing process showing an embodiment of the present invention.

FIG. 3 is a cross-sectional view (part 2) of an LED array electrode manufacturing process showing the embodiment of the present invention.

FIG. 4 is an explanatory view of a conventional LED array formed by gas phase diffusion of a diffusion region.

FIG. 5 is an explanatory view of a conventional LED array by solid-phase diffusion of 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]

Reference Signs List 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 planned region 21A Negative resist pattern 23 Metal thin film mainly composed of Al 23A p electrode pattern (metal thin film pattern)

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-7-122781 (JP, A) JP-A-2-2646 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 33/00

Claims (2)

(57) [Claims] Together with a 1. A (a) n-type compound openings for selective diffusion of Zn into the semiconductor substrate, also AlN film
Forming a diffusion mask made of an Al ₂ O ₃ film ; (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. (D) applying a resist on the entire surface of the semiconductor substrate and patterning the resist to form a p-electrode pattern mainly composed of Al; and (e) forming an electrode film on the entire surface. (F) a step of forming a p-electrode pattern by a lift-off method; and (g) a step of forming an n-electrode on the back surface of the semiconductor substrate. 2. A process according to claim 1 Symbol placement of the LED array, wherein to form another layer of the interlayer insulating film on a diffusion mask, the interlayer insulating film or the AlN film or Al ₂ O ₃ film <br / > A method of manufacturing an LED array, wherein the method is a thin film.