JPH08339966A - Method of selective solid phase diffusion in compound semiconductor and manufacture of light emitting diode and light emitting diode array - Google Patents

Abstract

PURPOSE: To form a uniform diffusion layer with less variation by forming a diffusion source film containing an impurity for establishing a second conductivity type on a compound semiconductor substrate of a first conductivity type, and forming an insular cap film on the diffusion source film above the intended diffusion region in the substrate. CONSTITUTION: A ZnO film 13 as diffusion source film is formed on a n-type GaAs1- XPX epitaxial substrate (0<=X<=0.4) 11 by sputtering. An AlN film is formed on the ZnO film 13, and then an insular cap film 15 is formed so that it will be left only on the portion 13a of the diffusion source film on the intended diffusion region 12 in the substrate 11. Then heat treatment is performed to diffuse impurities from the diffusion source film 13 to the intended diffusion region 12 to form an impurity diffusion region 17 of a second conductivity type. The substrate 11 is subjected to heat treatment in a nitrogen atmosphere. As a result, an impurity of Zn is diffused from the portion 13a of the diffusion source film covered with the cap film 15 to the intended diffusion region 12 in the substrate 11, and a p-type impurity diffusion region 17 is thereby formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for selectively solid-phase diffusing impurities in a compound semiconductor, and a method for manufacturing a light emitting diode and a light emitting diode array, respectively, using this solid phase diffusion method.

[0002]

2. Description of the Related Art An example of a method of selectively solid-phase diffusing impurities into a compound semiconductor is described in a document: Met.Res.Soc.Symp.Proc.Vol.
36, 1985, materials Research Society, pp.438-488 (hereinafter referred to as reference). According to this document, the following 1. And 2. There are two methods shown in.

1. First, on a compound semiconductor substrate of the first conductivity type (hereinafter, also referred to as a substrate), a selective diffusion mask having a window exposing a diffusion planned region of the substrate is formed. Next, a diffusion source film containing an impurity that determines the second conductivity type and a cap film for preventing the evaporation and scattering of the impurity are sequentially provided so as to cover the selective diffusion mask.
Next, heat treatment is performed to selectively diffuse the impurities from the diffusion source film through the window of the mask into the diffusion planned region of the substrate to form a second conductivity type impurity diffusion region.

[0004] 2. First, on a substrate of the first conductivity type,
A diffusion source film containing an impurity that determines the second conductivity type is provided on the diffusion planned region of the substrate. Next, after covering the diffusion source film with a cap film, heat treatment is performed to diffuse the impurities into the diffusion planned region to form a second conductivity type impurity diffusion region.

The selective solid-phase diffusion method as described above is performed during the manufacturing process of the light emitting diode, the light emitting diode array, etc.
It is known to be used later to form a region that functions as a light emitting region. After forming a diffusion region (a region that will later function as a light emitting region) by using these diffusion methods, by further forming an interlayer insulating film and an electrode, the light emitting diode devices are arranged side by side to form the device. is there.

[0006]

However, the conventional selective solid-phase diffusion method as disclosed in the above-mentioned documents has the following problems.
There were the following problems. For example, in the method of 1 in the above-mentioned document, when the substrate and the mask in the method of 2 and the substrate and the diffusion source film in the method of 2 are a combination of materials having different thermal expansion coefficients, stress on the substrate during heat treatment for diffusion is applied. Is large, and cracks may occur on the substrate surface. Therefore, the combination of film materials is limited.

Similarly, there is a risk that the surface of the cap film may be cracked due to the influence of the stress applied to the cap film by the diffusion source film during the heat treatment.

Further, when impurities are diffused in the substrate by solid phase diffusion, the impurities are diffused from the upper part of the substrate surface, so that the diffusion in the direction perpendicular to the substrate occurs, and at the same time, the impurities are always diffused into the substrate. Diffusion occurs in the lateral direction (horizontal direction). At this time, there is a case where the above-mentioned stress influences to cause abnormal diffusion. The lateral diffusion distance is generally similar to the vertical diffusion distance (sometimes referred to as diffusion depth), but when abnormal diffusion occurs, the lateral diffusion distance is twice the diffusion depth. It reaches 3 times. For example, when the selective solid-phase diffusion method is applied to the manufacture of a light emitting device or the like, abnormal diffusion in the lateral direction may occur.

The occurrence of cracks and abnormal lateral diffusion are
It is also affected by the shape and size of the diffused area, and therefore it is necessary to consider the shape and size of the diffused area.

In either method, the diffusion region is affected by step coverage (how much the film covering the step of the device covers). For example, in the method of 1 of the above-mentioned document, since the window is provided in the selective diffusion mask, this becomes a step, and due to the difference in the step coverage of the diffusion source film covering each window of the mask,
The size and shape of each diffusion region may vary. Further, in the method 2, the diffusion source film patterned in an island shape becomes a step, and the difference in the step coverage of the cap film covering each diffusion source film causes the variation in the size and shape of the diffusion region as well. Becomes

When the diffusion region varies, the light emitting region of the light emitting diode element also varies, and the amount of light emitted from the element also varies.

[0012] Therefore, even if the combination of the materials of the film and the size and shape of the region to be diffused are limited, it is possible to form a diffusion region that is uniform and has less variation, and the selected solid phase has few defects in the substrate or film. The emergence of diffusion methods was desired. In addition, it is possible to form a light emitting region that is uniform and has little variation, and a light emitting diode with few defects in the substrate and film
And the advent of a method for manufacturing a light emitting diode array has been desired.

[0013]

Therefore, the selective solid phase diffusion method of the present invention is characterized by including the following steps.

1). A diffusion source film containing impurities that determine the second conductivity type is provided on the first conductivity type compound semiconductor substrate.

2). An island-shaped cap film is formed on the diffusion source film portion above the diffusion planned region in the compound semiconductor substrate.

3). Impurities are diffused from the diffusion source film to the planned diffusion region by heat treatment to form a second conductivity type impurity diffusion region.

Further, according to the method of manufacturing a light emitting diode of the present invention, the compound semiconductor substrate of the first conductivity type is provided with the impurity diffusion region of the second conductivity type, and the light emitting window is formed in the impurity diffusion region. In manufacturing the light emitting diode, the above-described selective solid phase diffusion method is used to manufacture the light emitting diode by the following steps.

A diffusion source film containing an impurity that determines the second conductivity type is provided on the compound semiconductor substrate of the first conductivity type.

An island-shaped cap film is formed on the diffusion source film portion above the diffusion planned region in the compound semiconductor substrate.

Impurities are diffused from the diffusion source film to the planned diffusion region by heat treatment to form a second conductivity type impurity diffusion region.

After the interlayer insulating film is provided on the entire surface of the substrate after the above processing, the diffusion source film, the cap film and the interlayer insulating film on the diffusion region are removed so that the diffusion region is exposed. An opening as a light emitting window is formed in the diffusion source film and the interlayer insulating film.

Further, according to the method of manufacturing a light emitting diode array of the present invention, when the light emitting diode array chips are arranged in a matrix on the first conductivity type compound semiconductor substrate, the light emitting diode array chips are arranged in a column direction on the substrate. A plurality of photomask alignment marks are formed in the gaps between adjacent light emitting diode array chip formation regions.

On the substrate, there is provided a diffusion source film containing an impurity that determines the second conductivity type for diffusing into the diffusion planned region of the substrate.

An island-shaped cap film is formed on the diffusion source film by using the above-mentioned mark as a positioning reference.

Impurities are diffused from the diffusion source film to the planned diffusion region by heat treatment to form a second conductivity type impurity diffusion region.

The cap film and the diffusion source film are removed from the substrate on which the above processing is completed.

On the substrate, the above-mentioned mark is used as a positioning reference to provide an interlayer insulating film having an opening so that the diffusion region is exposed.

Using the above-mentioned mark as a positioning reference, an electrode patterned into a predetermined shape is formed.

[0029]

According to the selective solid phase diffusion method of the present invention described above, a diffusion source film containing an impurity that determines the second conductivity type is provided on a compound semiconductor substrate of the first conductivity type, and a diffusion source film in the substrate is planned. An island-shaped cap film is formed on the diffusion source film portion above the region. In this way, since the cap film is provided only on the diffusion source film portion in the region to be diffused, the stress applied to the diffusion source film is smaller than that of the conventional cap film provided over the entire surface, and thus cracks are generated. There is almost no risk of Further, since the diffusion source film is provided flat so that the entire surface is in contact with the substrate, the stress applied to the substrate becomes uniform and there is no risk of cracks occurring. Therefore, there is no fear of abnormal diffusion in the lateral direction due to stress.

Further, diffusion is performed only by providing an island-shaped cap film on the diffusion source film provided on the entire surface of the substrate, and since there is no film covering the step portion as in the conventional case, there is no impurity diffusion region (diffusion region). ) Is not affected by step coverage.

Further, according to the method of manufacturing a light emitting diode of the present invention, since the diffusion region is formed as the light emitting region by using the selective solid-phase diffusion method of the present invention, a light emitting diode having a small variation in the light emitting region can be obtained. Can be formed.

Further, according to the method of manufacturing a light emitting diode array of the present invention, in forming the light emitting diode array chips on the substrate in a matrix, first, the light emitting diodes adjacent to each other in the column direction on the substrate are first formed. A plurality of marks for aligning the photomask are formed in the gaps between the regions where the diode array chips will be formed. Therefore, this mark can be used as a positioning reference for the photomask used for all pattern formation performed in the manufacturing process. Further, since the alignment mark is provided, it is possible to form the interlayer insulating film after removing the cap film and the diffusion source film, which have also been used as a reference for positioning in the past, from the substrate after the diffusion. Therefore, after forming the diffusion region, it is not necessary to provide the interlayer insulating film on the film that may be damaged by the heat treatment, and there is no possibility that a failure will occur in the subsequent process and a defective product will be generated. A diode array can be formed.

[0033]

Embodiments of the present invention will be described below with reference to the drawings. Each drawing merely schematically shows the size, shape, arrangement relationship and the like of each component so that the invention can be understood. Further, in the following description, specific materials and conditions may be used, but these are merely preferred examples, and are not limited to these materials and conditions. In each figure, the same components are shown with the same numbers.
The hatching showing the cross section is omitted except for a part.

<First Embodiment> FIGS. 1A to 1D and FIGS. 2A to 2D show a method of selective solid-phase diffusion into a compound semiconductor of the present application, and a light emitting diode. FIG. 4 is a schematic process diagram for explaining the first embodiment of the manufacturing method. These two inventions will be described in the same embodiment. here,
The process from the selective solid phase diffusion to the completion of the light emitting diode is shown in a sectional view of the element around the diffusion. 1 and 2, hatching showing a cross section is omitted except for a part.

According to the selective solid-phase diffusion method for compound semiconductor of the present invention, first, a diffusion source film containing an impurity for determining the second conductivity type is provided on a compound semiconductor substrate of the first conductivity type. In this embodiment, a ZnO film 13 is used as a diffusion source film on an n-type GaAs _1-X P _X epitaxial substrate (0 ≦ X ≦ 0.4) 11 by using a suitable film forming method such as a sputtering method. (FIG. 1A). If the thickness of the diffusion source film is too thin, it will not function as a diffusion source film.
Further, if the thickness is too large, the impurities may diffuse into a region other than the planned diffusion region. Therefore, in order to diffuse the impurities only into the region to be diffused, in the case of the ZnO film, it is preferable to provide the ZnO film so that the film thickness does not exceed 50 nm. The diffusion source film is S doped with Zn.
iO ₂ film may be. In that case, preferably 150 nm
It is provided so that the film thickness does not exceed.

Next, an island-shaped cap film 15 is formed on the diffusion source film portion 13a above the diffusion planned region 12 in the substrate 11 ((C) of FIG. 1). In this example, first, Zn
An AiN film 14 is provided on the O film 13 by a suitable film forming method ((B) of FIG. 1). After that, using a photolithography technique, the island-shaped cap film 15 is formed so that only the diffusion source film portion 13a above the diffusion planned region 12 (shown as an approximate region in the figure) 12 in the substrate 11 remains.
Are formed ((C) in FIG. 1). At this time, hot phosphoric acid is used for etching the AlN film. Zn diffusion source film (Zn
SiO ₂ doped with O or Zn. Hereinafter, SiO ₂ doped with Zn will be referred to as ZnO.SiO ₂ . ) Is not etched by hot phosphoric acid, AlN is suitable as a material for the cap film. For the same reason, Al ₂ O ₃ may be used as the material of the cap film.

Next, impurities are diffused from the diffusion source film 13 to the diffusion planned region 12 by heat treatment to form a second conductivity type impurity diffusion region 17. In this embodiment, the substrate 11 which has been subjected to the above-mentioned processing is heat-treated at 700 ° C. for 1 hour in a nitrogen atmosphere, so that the diffusion source film 13 is removed from the substrate 11.
Was subjected to heat diffusion treatment. By this thermal diffusion treatment, the diffusion source film portion 13a substantially covered with the cap film 15 is substantially formed.
From the above, the impurity Zn was diffused into the diffusion planned region 12 in the substrate 11 to form the p-type impurity diffusion region 17 having a diffusion depth of 1 to 2 μm ((D) of FIG. 1). Here, it is possible to set a desired diffusion depth by the time and temperature of the heat treatment. Thus, the impurities in the diffusion source film portion 13a covered with the cap film 15 greatly contribute to the diffusion into the substrate 11 because the impurities in the diffusion source film portion not covered with the cap film 15 are subjected to the heat treatment. It is considered that it is evaporated and scattered into the atmosphere and hardly diffuses into the substrate 11.

As can be understood from the above description, according to the selective solid-phase diffusion method for compound semiconductor of the present invention, the cap film 15 is formed only on the diffusion source film portion 13a on the planned diffusion region 12 in the substrate 11. Since the cap film is provided, the stress applied from the cap film to the diffusion source film is less than that of the conventional cap film provided over the entire surface, and thus the risk of cracks is reduced. The diffusion source film 13 is the substrate 1
Since it is provided flat so that the entire surface is in contact with 1, the stress applied from the diffusion source film 13 to the substrate becomes uniform, and there is almost no possibility of cracks. Therefore, there is no fear of abnormal diffusion in the lateral direction due to stress.

Further, since diffusion can be performed only by providing the island-shaped cap film 15 on the diffusion source film 13 provided on the entire surface of the substrate 11, the diffusion region is not affected by the step coverage. Therefore, it is possible to form a uniform diffusion region with little variation.

Next, the manufacturing method of the light emitting diode of the present invention will be described. According to the method for manufacturing a light emitting diode of the present invention, first, diffusion is performed according to the above-described selective solid phase diffusion method into the compound semiconductor of the present invention ((A) to (D) of FIG. 1). In the present invention, after the interlayer insulating film 19 is provided on the entire surface of the substrate 11, the diffusion source film, the cap film, and the interlayer insulating film on the diffusion region 17 are removed so that the diffusion region 17 is exposed. Thus, the opening 21 as a light emitting window is formed in the diffusion source film and the interlayer insulating film ((C) of FIG. 2). In this embodiment, first, a SiN film 19 is provided as an interlayer insulating film on the entire surface of the substrate 11 which has been subjected to the diffusion process ((A) of FIG. 2). Since hot phosphoric acid is used as an etchant when forming electrodes to be described later, it is preferable to use a material having etching resistance to hot phosphoric acid for the interlayer insulating film. Therefore, a SiO ₂ film or a PSG film may be used instead of the SiN film. next,
The diffusion source film portion 13a, the cap film 15, and the interlayer insulating film portion 19a on the diffusion region 17 are removed by photolithography to expose the diffusion region 17 and form an opening 21 as a light emitting window (FIG. 2). (B)). The opening 21 penetrates the diffusion source film and the interlayer insulating film, and by providing the opening 21, the patterned diffusion source film 13b and the patterned interlayer insulating film 19 are formed.
b is formed. At this time, buffered hydrofluoric acid was used for etching the SiN film 19 and ZnO film 13, and hot phosphoric acid was used for removing the cap film (AlN).

After that, the P-side electrode 23 made of, for example, an Al electrode is exposed from the opening 21 in the p-type diffusion region 17.
To the patterned interlayer insulating film 19b,
It is formed in a predetermined pattern. Hot phosphoric acid was used for etching. Then, on the back surface of the substrate 11 opposite to the surface on which the P-side electrode 23 is provided, the N-side electrode 25 made of an Au alloy electrode is provided after polishing the back surface to complete the light emitting diode (FIG. 2 (C)).

As described above, according to the method for manufacturing a light emitting diode of the present invention, since the uniform diffusion region without variations is formed as the light emitting region by using the selective solid phase diffusion method of the present invention, the light emitting region. It is possible to form a light emitting diode with less variation.

A light emitting diode array can be formed by arranging a plurality of light emitting diodes formed according to the above-described method for manufacturing a light emitting diode side by side.

Next, a modified example of the first embodiment will be described. In the modified selective solid phase diffusion method, a ZnO.SiO ₂ film is provided as a diffusion source film, preferably with a film thickness not exceeding 150 nm. Then, when the SiN film is used as the cap film and is patterned into an island shape by photolithography, the SiN film portion other than the portion to be left as the cap film is removed by dry etching using a mixed gas of CF ₄ and O _2. .

Further, in the method for forming a light emitting diode of the modified example, when the opening is formed in the step after the selective solid phase diffusion, the cap film (SiN film) on the diffusion source film and the diffusion source film (ZnO. SiO ₂ film) and interlayer insulating film (SiN
The etching of the film) was performed at once using buffered hydrofluoric acid. The other steps are similar to those of the first embodiment, and detailed description thereof will be omitted.

In the modified example, the same effect as that of the first embodiment is recognized, and in addition, the cap film is further formed.
Since dry etching suitable for forming a fine pattern is used, the pattern does not collapse,
A more precise and clean diffusion area can be formed. Therefore, it is possible to form a light emitting diode and a light emitting diode array with less variation.

<Second Embodiment> In the second embodiment, a method of manufacturing the light emitting diode array of the present invention will be described.

In the method for manufacturing a light-emitting diode array of the present invention described in the first embodiment, the diffusion source film after the selective solid-phase diffusion is left until the end except the portion removed for forming the opening. It is an element as it is. However, the properties of the film after the heat treatment may change, such as a decrease in the etching rate. Further, in the portion of the diffusion source film which is not covered with the cap film, impurities are evaporated and scattered during the heat treatment, so that the adhesion of the film may be deteriorated. Therefore, if the diffusion source film and the cap film on the substrate, which may have been damaged by the heat treatment after the diffusion region is formed, are removed, there is no possibility that a failure will occur due to a failure in the subsequent steps, resulting in higher reliability. It is possible to form a high light emitting diode array.

However, if all the film on the substrate is removed,
Since the interlayer insulating film provided thereafter is flat without unevenness as when there is a film, it becomes impossible to determine the position of the diffusion region when forming the opening, that is, the position where the opening should be formed.

Therefore, in the method for manufacturing a light-emitting diode array of the present invention, by providing a photomask alignment mark (hereinafter also referred to as a mark), which serves as a positioning reference, on the substrate, the photomask alignment mark is formed on the substrate after diffusion. The position of the diffusion region can be seen even if the film is completely removed.

FIGS. 3A and 3B show the mutual positional relationship between the mark formed on the substrate and the light emitting diode array chip in the second embodiment in the method for manufacturing a light emitting diode array according to the present invention. FIG. 3 is a schematic plan view showing 3A is a view of the surface of the compound semiconductor substrate (wafer) 110 on the side where the light emitting region is formed, viewed from above, and FIG. 3B is P of FIG. 3A. It is an enlarged view of the part. As shown in FIG. 3, a plurality of marks 33 are formed in the gaps 31 between the light emitting diode array chips 30 which are arranged in a matrix form and which are adjacent to each other in the column direction. The number, arrangement, and size of the marks are not limited to the illustrated example.
It also changes depending on the number of masks used. In this embodiment, two marks 33 are formed in one gap 31. Positioning can be easily performed by aligning the mark 33 provided on the substrate 110 with the mark at a predetermined position of the photomask for pattern formation.

FIGS. 4 to 7 are views for explaining the method of manufacturing the light emitting diode array of the present invention.

FIG. 4A shows a light emitting diode array chip 30 provided on the substrate 110 and adjacent in the column direction.
4A and 4B are plan views showing a mark 33 provided in the gap 31. FIG. 4B is a view when FIG. 4A is cut along the line XX and seen in the direction of the arrow. is there. Further, FIG. 4C is a diagram when FIG. 4A is cut along the line YY and viewed in the direction of the arrow. 4A to 4C, 170 is a diffusion region, 190b is a patterned interlayer insulating film, 210 is an opening, 230 is a P-side electrode, 250
Shows the N-side electrode, which will be described in detail later.

In FIG. 4A, the individual elements (light emitting diodes) forming the light emitting diode array are marked with marks 3.
Although only two adjacent ones are shown by sandwiching 3, a plurality of elements are actually arranged side by side. And FIG.
FIG. 7 is a diagram showing a stepwise process of the method for manufacturing a light emitting diode array of the present invention in the vicinity of FIG. 4B.

According to the light emitting diode array of the present invention, first, the gap 3 between the light emitting diode array forming regions 32 adjacent in the column direction on the first conductivity type substrate 110.
1, a plurality of photomask alignment marks 33 are formed. In this example, by photolithography, n
Type GaAs _1-X P _X epitaxial substrate 110 on which light emitting diode array forming regions 32 adjacent in the column direction are formed
For each gap 31 of, using photolithography technology,
The substrate is etched to a predetermined depth to form two cruciform marks 33 in plan view (FIG. 5A).

Next, on the substrate 110, a diffusion source film containing an impurity for determining the second conductivity type for diffusing into the diffusion planned region 120 of the substrate 110 is provided. In this embodiment, the ZnO.SiO ₂ film 130 is used as the diffusion source film, preferably to a thickness not exceeding 150 nm.
It is provided by a suitable film forming method. At this time, ZnO / SiO ₂
The film 130 does not make the mark 33 unrecognizable, and the diffusion source film in the portion covering the mark 33 is dented (FIG. 5B).

Next, the island-shaped cap film 150 is formed on the diffusion source film by using the mark 33 as a positioning reference ((A) of FIG. 6). Here, first, ZnO.SiO ₂
The SiN film 140 is provided on the film 130 by a suitable film forming method (FIG. 5C). After that, using a photolithography technique, only the diffusion source film portion 130a above the diffusion planned region 120 in the substrate 110 is left,
The island-shaped cap film 150 is formed. At this time, the mark 33 was used as a positioning reference for aligning the photomask (not shown) used for forming the cap film. Then, the island-shaped cap film 150 is formed so that only the diffusion source film portion 130a above the diffusion planned region 120 in the substrate 110 remains ((A) of FIG. 6). At this time, the SiN film portion other than the portion left as the cap film 150 is removed by dry etching using a mixed gas of CF ₄ and O ₂ . Therefore, fine and accurate pattern formation can be performed.

Next, the impurities are diffused from the diffusion source film 130 to the planned diffusion region 120 by heat treatment to form the second conductivity type impurity diffusion region 170. In this example,
The substrate 110 that has undergone the above-described processing is placed in a nitrogen atmosphere at 70
By performing heat treatment at 0 ° C. for 1 hour, the cap film 1
From the diffusion source film portion 130a covered with 50 to the substrate 110
Impurity Zn is diffused into the diffusion planned region 120 therein, and the p-type impurity diffusion region 170 has a diffusion depth of about 1 to 2 μm.
Was formed ((B) of FIG. 6).

Next, the cap film 150 and the diffusion source film 130 are removed from the substrate 110 on which the above processing has been completed.
In this embodiment, SiN, which is a cap film, is formed by using hydrofluoric acid.
The film 150 and the ZnO film 130 that is the diffusion source film were removed from the substrate 110. At this time, the mark 33 is exposed ((C) of FIG. 6).

Next, on the substrate 110, a patterned interlayer insulating film having an opening is formed so that the impurity diffusion region 170 is exposed using the mark 33 as a positioning reference. In this embodiment, first, the SiN film 190 as an interlayer insulating film is provided on the entire surface of the substrate 110 by a suitable film forming method. At this time, the mark 33 does not become unrecognizable by the SiN film 190, and the mark 33 does not become unrecognizable.
A dent is formed in the SiN film 190 in the portion that covers (FIG. 7A). Other materials for the interlayer insulating film include A
1N or Al ₂ O ₃ may be used. Next, the SiN film portion 190a (FIG. 7A) on the diffusion region 170 is removed by photolithography to provide an opening 210 as a light emitting window, and the patterned interlayer insulating film 190 is formed.
b is formed ((B) of FIG. 7). At this time, the mark 33 was used as a positioning reference for aligning the photomask (not shown) used for forming the patterned interlayer insulating film. In addition, the SiN film portion 190 on the diffusion region 170
The removal of a is performed by dry etching using a mixed gas of CF ₄ and O ₂ .

Next, using the mark 33 as a positioning reference, the electrode 230 patterned into a predetermined shape is formed. In this embodiment, as in the manufacture of the light emitting diode of the first embodiment, the P-side electrode 230 made of an Al electrode is
From the p-type diffusion region 170 exposed from the opening 210,
A predetermined pattern is formed over the patterned interlayer insulating film 190b. Hot phosphoric acid was used for etching. Then, on the back surface of the substrate 110 opposite to the surface on which the P-side electrode 230 is provided, an N-side electrode 250 made of an Au alloy electrode is provided after polishing the back surface. A light emitting diode array as shown in FIG. 7C is completed (FIG. 7C).

As described above, according to the method of manufacturing the light emitting diode array of the present invention, the cap film 150 is formed on the substrate 110 in the same manner as the selective solid phase diffusion method to the compound semiconductor of the present invention shown in the first embodiment. Since it is provided only in the diffusion source film portion 130a on the planned diffusion region 120, the stress applied from the cap film to the diffusion source film is smaller than that of the conventional cap film provided over the entire surface, and thus cracks are generated. It is less likely to occur. In addition, the diffusion source film 130
Is provided flat so that the entire surface is in contact with the substrate 11, so that the stress applied from the diffusion source film 130 to the substrate is uniform and there is almost no possibility of cracks. Therefore, there is no fear of abnormal diffusion in the lateral direction due to stress.

Further, since diffusion can be performed only by providing the island-shaped cap film 150 on the diffusion source film 130 provided on the entire surface of the substrate 110, the diffusion region is not affected by the step coverage. Therefore, it is possible to form a uniform diffusion region, that is, a light emitting region with little variation.

Further, since the mark 33 is first provided on the substrate 110, this mark can be used as a positioning reference for the photomask used for all pattern formation performed in the manufacturing process. Further, since the mark 33 is provided, after the diffusion, the cap film and the diffusion source film, which have also been a standard for positioning in the past, can be removed from the substrate 110, and then the interlayer insulating film can be formed. Therefore, after forming the diffusion region 170, it is not necessary to provide the interlayer insulating film 190 on the film that may be damaged by the heat treatment, and there is no possibility that a failure will occur in a subsequent process and a defective product will be generated. It is possible to form a high light emitting diode array. Further, since dry etching using a mixed gas of CF ₄ and O ₂ is used to form the opening 210, it is possible to form a light emitting diode array having a more precise and uniform light emitting region.

Obviously, the invention is not limited to the embodiments described above. For example, in the above-described embodiments, the GaAs _1-X P _X substrate was used for all, but G
You may use aAs, GaAlAs, etc. Further, in each of the embodiments, the p-type impurity is diffused into the n-type semiconductor, but the present invention can also be applied to the case where the material is changed to diffuse the n-type impurity into the p-type semiconductor. Further, in the embodiment of the method for manufacturing the light emitting diode array, only one layer of the interlayer insulating film is provided, but it may have a two-layer structure. For example,
A two-layer structure of a SiO ₂ film and a SiN film is used. In this case, the SiN film is formed by dry etching using a mixed gas of CF ₄ and O ₂ to form the opening, and SiO 2 is formed.
_{2 The} film is formed by wet etching using hot phosphoric acid or buffered hydrofluoric acid. Although a wet etching step is performed, by adopting a two-layer structure, even if a defect such as a pinhole occurs in the first layer film, it can be alleviated by the second layer film, and the electrode wiring-substrate It can prevent short circuit.

[0066]

As is apparent from the above description, according to the selective solid phase diffusion method for compound semiconductor of the present invention,
Since the cap film is provided only on the diffusion source film portion of the region to be diffused, the stress applied to the diffusion source film is smaller than that of the conventional cap film that is provided on the entire surface, and therefore there is almost no possibility of cracks. Absent. Further, since the diffusion source film is provided flat so that the entire surface is in contact with the substrate, the stress applied to the substrate becomes uniform and there is no risk of cracks occurring. Therefore, there is no fear of abnormal diffusion in the lateral direction due to stress.

Further, diffusion is performed only by providing an island-shaped cap film on the diffusion source film provided on the entire surface of the substrate, and since there is no film that covers the stepped portion as in the conventional case, the diffusion region has step coverage. Not affected.

Further, according to the method of manufacturing a light emitting diode of the present invention, since the diffusion region is formed as the light emitting region by using the selective solid phase diffusion method of the present invention, a light emitting diode having a small variation in the light emitting region can be obtained. Can be formed.

According to the method of manufacturing a light emitting diode array of the present invention, first, a plurality of photomask alignment marks are formed on the substrate. Therefore, this mark can be used as a positioning reference for the photomask used for all pattern formation performed in the manufacturing process. Also, since the alignment mark is provided, it is not necessary to provide an interlayer insulating film on the film that may have been damaged by the heat treatment after the diffusion region has been formed, and there is a risk of failure in subsequent steps and production of defective products. Is eliminated, and a more reliable light emitting diode array can be formed.

[Brief description of drawings]

1 (A) to 1 (D) are schematic manufacturing process diagrams in an example of a selective solid-phase diffusion method into a compound semiconductor and a manufacturing method of a light emitting diode of the present application.

2A to 2C are schematic manufacturing process diagrams in the examples of the method of selective solid-phase diffusion into a compound semiconductor of the present application and the method of manufacturing a light emitting diode, which are subsequent to FIG. .

3A and 3B are schematic plan views for explaining the positional relationship between the light emitting diode array and the alignment mark.

FIG. 4A is a plan view for explaining an embodiment of a method for manufacturing a light emitting diode array of this application, and FIG.
And (C) are cross-sectional views thereof.

5 (A) to (C) are schematic manufacturing process diagrams in an embodiment of a method for manufacturing a light emitting diode array of the present application.

6A to 6C are schematic manufacturing process diagrams in the example of the method for manufacturing the light emitting diode array of the present application, which are subsequent to FIG.

7A to 7C are schematic manufacturing process diagrams in an example of the method for manufacturing the light emitting diode array of the present application, which is subsequent to FIG.

[Explanation of symbols]

 11, 110: Compound semiconductor substrate (substrate) 12, 120: Diffusion planned region 13, 130: Diffusion source film 13a, 130a: Diffusion source film part on the planned diffusion region 14: AlN film 140: SiN film 15, 150: Cap Films 17, 170: Impurity diffusion regions 19, 190: Interlayer insulating films 19a, 190a: Interlayer insulating film portions 19b, 190b: Patterned interlayer insulating films 21, 210: Openings 23, 230: P-side electrode 25 , 250: N-side electrode 30: Light emitting diode array chip 31: Gap 33: Mark

Claims (7)

[Claims] 1. A step of providing a diffusion source film containing an impurity that determines a second conductivity type on a compound semiconductor substrate of a first conductivity type, and the diffusion source film above a diffusion planned region in the compound semiconductor substrate. A step of forming an island-shaped cap film on the portion, and a step of forming a second conductivity type impurity diffusion region by diffusing the impurities from the diffusion source film to the diffusion planned region by heat treatment. A method for selective solid-diffusion into a compound semiconductor. 2. The method of selective solid phase diffusion into a compound semiconductor according to claim 1, wherein the substrate is GaAs _1-X P _X , GaAs, and GaA.
An n-type compound semiconductor substrate made of one material selected from 1As, wherein the diffusion source film is ZnO or Zn ₂ -doped SiO ₂
And a cap film made of AlN or Al ₂ O ₃ for selective solid phase diffusion into a compound semiconductor. 3. The method of selective solid phase diffusion into a compound semiconductor according to claim 1, wherein the substrate is GaAs _1-X P _X , GaAs, and GaA.
When the n-type compound semiconductor substrate is made of one material selected from 1As, the diffusion source film is a film made of ZnO, and the cap film is a film made of SiN, the cap film is CF ₄ and O ₂ A method for selective solid phase diffusion into a compound semiconductor, which is characterized by being formed by etching using a mixed gas of. 4. A method of manufacturing a light emitting diode, comprising: a compound semiconductor substrate of a first conductivity type, an impurity diffusion region of a second conductivity type; and a light emitting window formed in the impurity diffusion region. Providing a diffusion source film containing an impurity that determines the second conductivity type on a compound semiconductor substrate; and forming an island-shaped cap film on the diffusion source film portion above a diffusion planned region in the compound semiconductor substrate. And a step of forming the second conductivity type impurity diffusion region by diffusing the impurities from the diffusion source film to the diffusion planned region by heat treatment, and performing interlayer insulation on the entire surface of the substrate on which the above process is completed. After the film is provided, the diffusion source film, the cap film, and the interlayer insulating film on the diffusion region are removed so that the diffusion region is exposed, thereby forming a light emitting window in the diffusion source film and the interlayer insulating film. of Method of manufacturing a light-emitting diode which comprises a step of forming a mouth. 5. When forming light emitting diode array chips in a matrix form on a compound semiconductor substrate of the first conductivity type, the light emitting diode array chips are formed in a gap between adjacent regions in the column direction on the substrate. A step of forming a plurality of photomask alignment marks, a step of providing a diffusion source film on the substrate, the diffusion source film including an impurity for determining a second conductivity type for diffusing into a diffusion planned region of the substrate, A step of forming an island-shaped cap film on the diffusion source film by using the mark as a positioning reference; and a step of diffusing the impurities from the diffusion source film to the diffusion planned region by a heat treatment to obtain impurities of the second conductivity type. A step of forming a diffusion region, a step of removing the cap film and the diffusion source film from the substrate that has been subjected to the above processing, and a mark for positioning the mark on the substrate. And a patterned interlayer insulating film having an opening so that the diffusion region is exposed, and a step of forming a patterned electrode in a predetermined shape by using the mark as a positioning reference. A method for manufacturing a light emitting diode array, comprising: 6. The method of manufacturing a light-emitting diode array according to claim 5, wherein the substrate is GaAs _1-X P _X , GaAs, and GaA.
When the n-type compound semiconductor substrate is made of one material selected from 1As, the diffusion source film is a film made of ZnO, and the cap film and the interlayer insulating film are films made of SiN, the opening and the electrode are formed. Is formed by dry etching using a mixed gas of CF ₄ and O ₂ . 7. The method for manufacturing a light emitting diode array according to claim 5, wherein the substrate is GaAs _1-X P _X , GaAs, and GaA.
When the n-type compound semiconductor substrate is made of one material selected from 1As, the diffusion source film is a film made of ZnO, and the cap film is a film made of SiN, the interlayer insulating film is a SiO ₂ film, A method of manufacturing a light-emitting diode array, characterized in that a laminated film in which a SiN film is provided in this order is used.