JPH09181051A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a pattern having approx. vertical end faces at low cost and high accuracy, without using a complicated process. SOLUTION: An Si3 N4 etching stop layer 3, an SiO2 spacer layer 4 and an Si3 N4 edge forming layer 5 are formed on an Si type film 2 to be etched. Using a resist pattern 6 as a mask, the layers 5 and 4 are dry etched to form openings 7. The layer 4 is side etched to form edges 5a at the layer 5. A metal is vacuum evaporated from a direction normal to the surface of a substrate to form a metal film 8 on the stop layer 3 at parts of the openings 7. After removing the layers 4 and 5, the layer 3 and film 2 are dry etched to pattern the film 2, using the metal film 8 as a mask.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern forming method, and is particularly suitable for application to forming a pattern having an end face substantially vertical to the surface of a substrate.

[0002]

2. Description of the Related Art Conventionally, when a film to be etched made of silicon (Si) or its compound silicon dioxide (SiO ₂ ) or silicon nitride (Si ₃ N ₄ ) is patterned by etching, the film to be etched is After forming a resist pattern by photolithography on the substrate, dry etching is generally performed using this resist pattern as a mask.

[0003]

However, usually,
Since a taper is formed on the end face of the resist pattern, a taper having an angle corresponding to the taper angle of the resist pattern is also formed on the end face of the film to be etched which is patterned by etching using the resist pattern as a mask. . Therefore, if it is necessary to make the end surface of the film to be etched after patterning vertical,
It was necessary to control the taper angle of the resist pattern, and a complicated process was required for that control (for example, the 1987 Union of Electrical Engineers of Japan, Proc.
(1982)).

Further, when the etching selection ratio of the film to be etched with respect to the resist pattern is small, for example, 5 or less, the receding of the resist pattern occurring during etching becomes large, so that the taper angle of the resist pattern can be controlled with higher accuracy. Required by. For this reason, a special dry etching apparatus capable of obtaining a high etching selection ratio is required, resulting in an increase in etching cost.

Therefore, an object of the present invention is to provide a pattern forming method capable of forming a pattern having an end face substantially perpendicular to the surface of a substrate at low cost and with high accuracy without using a complicated process. It is in.

[0006]

In order to achieve the above object, the present invention comprises a step of sequentially forming a first film and a second film having different etching characteristics on a substrate, and a second step.
Forming an opening by sequentially etching the first film and the first film, and increasing the width of the opening in the first film portion by side-etching the first film; A step of depositing a film made of a metal-based material on the substrate in the opening portion using the second film as a mask from a substantially vertical direction, and removing the first film and the second film by etching, And a step of forming a pattern by etching the substrate using the film as a mask.

In the present invention, a dry etching method, particularly an anisotropic dry etching method is typically used for the etching for forming the openings in the first film and the second film and the etching of the substrate. To be

In the present invention, wet etching is typically used for the side etching of the first film.

In the present invention, a vacuum evaporation method is typically used for depositing a film made of a metal material.

In the present invention, the uppermost layer of the substrate is typically made of a material having etching resistance when etching the first film.

In the present invention, typically the substrate is
It is composed of a base substrate, a film for pattern formation on the base substrate, and a film made of a material having etching resistance when the first film on the film for pattern formation is etched.

In this case, the film made of a material having etching resistance when etching the first film is, for example, S.
i ₃ N ₄ . The pattern forming film is made of, for example, Si or a compound thereof. Here, when a dry etching method is used for the etching for patterning the pattern forming film made of Si or a compound thereof, a gas containing fluorine (F), for example, CF ₄ is preferably used as the etching gas. To be

In the present invention, the first film is, for example, S
consists iO _2, the second film is made of for example Si ₃ N _4. Here, when a dry etching method is used for etching for forming openings in these SiO ₂ film and Si ₃ N ₄ film, a gas containing F, for example, CF ₄ is preferably used as the etching gas. Furthermore, Si
When the wet etching method is used for the side etching of the O ₂ film, the etching liquid is hydrofluoric acid (HF).
Alternatively, ammonium fluoride (NH ₄ F) is preferably used.

In the present invention, the film made of a metal material is, for example, a metal such as iron (Fe), nickel (Ni), chromium (Cr), aluminum (Al), an alloy thereof, or the like. Membranes composed of those compounds can be used.

In the present invention, the base is a base substrate, a film for forming a first pattern on the base substrate, a film for forming a second pattern on the film for forming the first pattern, and a film for forming the second pattern. In some cases, the first film on the pattern forming film is formed of a material having etching resistance when the first film is etched.

In this case, the film for forming the first pattern is
For example, II of at least one of Al and Ga
Group III-V compound semiconductors containing Group I elements, especially A
It is composed of a III-V group compound semiconductor composed of N and at least one group III element selected from l, Ga and In. Specific examples of such III-V group compound semiconductors are Al _1-x Ga _x As, In _1-x Ga _x As, I.
n _1-x Ga _x P, Al _1-x Ga _x N, In _1-x Ga _x N
And so on. The second pattern forming film is made of, for example, Si or its compound.

In one embodiment of the present invention, for example, the base body includes a plurality of semiconductor layers forming a light emitting element.
These semiconductor layers are specifically a cladding layer and an active layer.

According to the present invention configured as described above, a film made of a metal material is deposited on the substrate in the opening portion using the second film as a mask from a direction substantially perpendicular to the surface of the substrate. As a result, the width of the metal film can be set to the same width as the opening of the second film with high accuracy. In addition, since the film made of this metal-based material generally has much higher etching resistance than photoresists, and its receding hardly occurs during etching, the base film is etched using this film made of this metal-based material as a mask. The end face of the pattern thus formed can be made substantially vertical to the surface of the substrate.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

1 to 7 show a pattern forming method according to the first embodiment of the present invention in the order of steps.

In the pattern forming method according to the first embodiment, as shown in FIG. 1, first, as shown in FIG. 1, CVD is performed on a Si-based etching target film 2 made of Si or a compound thereof which is previously formed on a base substrate 1. Si ₃ N ₄ etching stop layer 3, SiO ₂ spacer layer 4 and Si ₃ N ₄ edge forming layer 5 are sequentially formed by a vacuum method or a vacuum evaporation method. Thereafter, a resist pattern 6 having a shape corresponding to the pattern to be formed is formed on the Si ₃ N ₄ edge forming layer 5 by, for example, the photolithography method.

Here, the Si-based etching target film 2 is specifically, for example, a SiO ₂ film or a Si ₃ N ₄ film.
The thickness of the Si-based etching target film 2 is, for example, 1 μm.
m, the Si ₃ N ₄ etching stop layer 3 has a thickness of, for example, 50 nm, and the SiO ₂ spacer layer 4 has a thickness of, for example, 30 nm.
0 nm, the thickness of the Si ₃ N ₄ edge forming layer 5 is, for example, 30
nm.

Next, as shown in FIG. 2, using the resist pattern 6 as a mask and using the Si ₃ N ₄ etching stop layer 3, a gas containing F, for example, CF ₄ is used as an etching gas. Ion etching (R
By an anisotropic dry etching method such as IE),
The Si ₃ N ₄ edge forming layer 5 and the SiO ₂ spacer layer 4 are sequentially etched in a direction perpendicular to the substrate surface to form an opening 7
To form The end face of the opening 7 can be perpendicular to the substrate surface.

Next, as shown in FIG. 3, the resist pattern 6 and the Si ₃ N ₄ edge forming layer 5 are used as a mask.
For example, by side-etching the SiO ₂ spacer layer 4 by a wet etching method using HF or NH ₄ F as an etching solution, the end surface of the SiO ₂ spacer layer 4 is retracted by a predetermined distance in a direction parallel to the substrate surface. . As a result, the width of the opening 7 in the portion of the SiO ₂ spacer layer 4 is increased and the overhanging edge portion 5a is formed in the Si ₃ N ₄ edge forming layer 5.

Next, as shown in FIG. 4, a metal such as Fe, Ni or Al is vacuum-deposited in a direction perpendicular to the surface of the substrate so that the Si ₃ N ₄ etching stop layer 3 in the opening 7 is formed. A metal film 8 on at least Si
The thickness is smaller than that of the O ₂ spacer layer 4. At the time of this vacuum deposition, the Si ₃ N ₄ edge forming layer 5
The width of the metal film 8 formed on the Si ₃ N ₄ etching stop layer 3 becomes equal to the width of the opening 7 in the portion of the Si ₃ N ₄ edge forming layer 5 because the vapor deposition range is limited by the edge portion 5a of the. It is controlled with high precision. The metal film 8 is also formed on the resist pattern 6.

Next, as shown in FIG. 5, the resist pattern 6 is removed together with the metal film 8 formed thereon by a lift-off process.

Next, as shown in FIG. 6, after the Si ₃ N ₄ edge forming layer 5 and the SiO ₂ spacer layer 4 are removed by etching, RIE using CF ₄ as an etching gas with the metal film 8 as a mask. The Si ₃ N ₄ etching stop layer 3 and the Si-based etching target film 2 are sequentially etched in a direction perpendicular to the substrate surface by an anisotropic dry etching method such as the above method. At the time of this etching, since the etching selection ratio of the Si-based etching target film 2 to the metal film 8 can be made sufficiently large, the Si ₃ N ₄ etching stop layer 3 and the Si-based etching target film 2 after this etching can be obtained. The end face of can be perpendicular to the substrate surface.

Next, the metal film 8 is removed by etching by the wet etching method. As the etching solution for this wet etching, specifically, hydrochloric acid is used when Fe is used as the material of the metal film 8, nitric acid is used when Ni is used, and phosphoric acid is used when Al is used. To use. After that, the Si ₃ N ₄ etching stop layer 3 is removed by etching by a wet etching method using HF or NH ₄ F as an etching solution.

As described above, as shown in FIG. 7, the pattern 9 made of Si or its compound is formed.

As described above, according to the first embodiment, the metal film 8 which is hard to be eroded by the gas containing F used as an etching gas when the Si-based etching target film 2 is dry-etched is used as a mask. Since the system etching target film 2 is dry-etched in the direction perpendicular to the substrate surface, the pattern 9 having the end face perpendicular to the substrate surface can be easily formed with high accuracy.

Further, according to the first embodiment, in order to make the end face of the pattern 9 perpendicular to the substrate surface, it is necessary to control the taper angle of the resist pattern, which was necessary in the conventional technique described above. Therefore, there is no need for a complicated process associated with the control.

Further, according to the first embodiment, the etching selection ratio of the film to be etched with respect to the resist pattern, which was required to control the taper angle of the resist pattern with high accuracy in the conventional technique described above. Therefore, a special dry etching device having a high etching selectivity is not necessary, and a normal dry etching device having an etching selection ratio of 5 or less is sufficient.

As described above, the pattern 9 having the end face perpendicular to the substrate surface can be formed with low cost and high accuracy without using a complicated process.

Next, a second embodiment of the present invention will be described. In the second embodiment, the present invention is applied to manufacture of a semiconductor light emitting device.

That is, in the second embodiment, as shown in FIG. 8, first, a laser is formed on the underlying substrate 11 by metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). The n-type or p-type cladding layer 12, the active layer 13, and the p-type or n-type cladding layer 14 for forming the structure or the light emitting diode structure are sequentially grown. The clad layer 12, the active layer 13, and the clad layer 14 are made of, for example, Al _1-x Ga _x As, I
n _1-x Ga _x As, In _1-x Ga _x P, Al _1-x Ga _x
N, In _1-x Ga _x N and the like. Thereafter, the pattern 9 made of Si or its compound having an end face perpendicular to the substrate surface is formed on the clad layer 14 by the same method as in the first embodiment.

Next, using this pattern 9 as a mask, an anisotropic dry etching method such as an RIE method using a gas containing chlorine (Cl) as an etching gas is used to form a cladding in a direction perpendicular to the substrate surface. The layer 12 is etched to a middle depth in the thickness direction and patterned.
As a result, a laser structure or a light emitting diode structure including the clad layer 12, the active layer 13, and the clad layer 14 is formed. Clad layer 1 after this etching
2, the end faces of the active layer 13 and the cladding layer 14 can be perpendicular to the substrate surface.

According to this second embodiment, Al _1-x G
a _x As, In _1-x Ga _x As, In _1-x Ga _x P, A
Using the pattern 9 made of Si or its compound having a high etching resistance when etching the cladding layer 12, the active layer 13 and the cladding layer 14 made of l _1-x Ga _x N, In _1-x Ga _x N, etc. Since these clad layer 12, active layer 13 and clad layer 14 are dry-etched, these clad layer 12,
The active layer 13 and the cladding layer 14 can be patterned with high precision and easily. In particular, Al _1-x Ga
_{Although x} N and In _1-x Ga _x N are materials that have a low etching rate and are difficult to etch, the method according to the second embodiment also facilitates etching of such materials. Therefore, patterning can be easily performed. Further, since the end face of the pattern 9 used as an etching mask is perpendicular to the substrate surface, the end faces of the clad layer 12, the active layer 13, and the clad layer 14 which are patterned by etching using the pattern 9 as a mask also come to the substrate surface. Can be vertical.

Although the embodiments of the present invention have been specifically described above, the present invention is not limited to the above-mentioned embodiments, and various modifications can be made based on the technical idea of the present invention.

For example, the above-described first embodiment and second embodiment
The materials and numerical values mentioned in the above embodiment are merely examples, and different materials and numerical values may be used.

[0040]

As described above, according to the pattern forming method of the present invention, a pattern having an end face substantially vertical to the surface of a substrate can be formed at low cost and with high accuracy without using a complicated process. be able to.

[Brief description of the drawings]

FIG. 1 is a sectional view for explaining a pattern forming method according to a first embodiment of the present invention.

FIG. 2 is a sectional view for illustrating the pattern forming method according to the first embodiment of the present invention.

FIG. 3 is a sectional view for explaining the pattern forming method according to the first embodiment of the present invention.

FIG. 4 is a sectional view for illustrating the pattern forming method according to the first embodiment of the present invention.

FIG. 5 is a sectional view for illustrating the pattern forming method according to the first embodiment of the present invention.

FIG. 6 is a sectional view for illustrating the pattern forming method according to the first embodiment of the present invention.

FIG. 7 is a sectional view for illustrating the pattern forming method according to the first embodiment of the present invention.

FIG. 8 is a sectional view for illustrating the method for manufacturing the semiconductor light emitting device according to the second embodiment of the present invention.

FIG. 9 is a perspective view illustrating the method for manufacturing the semiconductor light emitting device according to the second embodiment of the present invention.

[Explanation of symbols]

1, 11 Base substrate 2 Si-based etching film 3 Si ₃ N ₄ etching stop layer 4 SiO ₂ spacer layer 5 Si ₃ N ₄ edge forming layer 6 resist pattern 7 opening 8 metal film 9 pattern 12, 14 clad layer 13 active layer

Claims (12)

[Claims] 1. A step of sequentially forming a first film and a second film having different etching characteristics on a substrate, and an opening is formed by sequentially etching the second film and the first film. A step of increasing the width of the opening in the portion of the first film by side etching the first film, and using the second film as a mask from a direction substantially perpendicular to the surface of the substrate. A step of depositing a film made of a metal-based material on the base in the opening portion; and etching and removing the first film and the second film, and then using the film made of the metal-based material as a mask, the base And a step of forming a pattern by etching. 2. The pattern forming method according to claim 1, wherein the uppermost layer of the substrate is made of a material having etching resistance when etching the first film. 3. The base comprises a base substrate, a pattern forming film on the base substrate, and a film made of a material having etching resistance when the first film on the pattern forming film is etched. 1. The method according to claim 1, wherein
The pattern forming method described in the above. 4. The pattern forming method according to claim 3, wherein the pattern forming film is made of Si or a compound thereof. 5. The pattern forming method according to claim _{3, wherein the} film made of a material having etching resistance when etching the first film is made of Si ₃ N ₄ . 6. The pattern forming method according to claim 1, wherein the first film is made of SiO ₂ . 7. The pattern forming method according to claim 1, wherein the second film is made of Si ₃ N ₄ . 8. The substrate is a base substrate, a film for forming a first pattern on the base substrate, a film for forming a second pattern on the film for forming the first pattern, and the second pattern. 2. The pattern forming method according to claim 1, further comprising a film made of a material having etching resistance when the first film on the forming film is etched. 9. The pattern forming method according to claim 8, wherein the first pattern forming film is made of a III-V group compound semiconductor containing at least one group III element of Al and Ga. . 10. The film for forming the first pattern is A.
9. The pattern forming method according to claim 8, wherein the pattern forming method comprises a III-V group compound semiconductor including N and at least one group III element selected from l, Ga and In. 11. The film for forming the second pattern is Si.
9. The pattern forming method according to claim 8, which is composed of a compound thereof. 12. The pattern forming method according to claim 1, wherein the substrate includes a plurality of semiconductor layers that form a light emitting element.