KR20010046815A - LIGA process and method manufacturing microstructures using the same - Google Patents

Abstract

PURPOSE: A LIGA process for forming an overhanging structure is provided which minimizes the manufacturing unit cost of the LIGA process. CONSTITUTION: The process comprises steps of: (i) forming an insulating film on top of a base plate; (ii) forming a sacrificing layer on the top of the insulating film; (iii) patterning the sacrificing layer to form a sacrificing layer pattern have an opening part; (iv) forming a plating basis layer on the top of the base plate; (v) forming a buffer layer on the top of the plating basis layer; (vi) coating the top of the buffer layer with a photosensitive film; (vii) forming a photosensitive film pattern of a plating frame of an overhanging structure through a photographing process of the photosensitive film by using a mask; (viii) etching the buffer layer uncovered by the photosensitive film pattern to expose the plating basis layer; (ix) forming a plating layer of overhanging structure on the top of the plating basis layer; (x) eliminating the photosensitive pattern; (xi) completely eliminating the buffer layer; (xii) eliminating the plating basis layer uncovered by the plating layer; and (xiii) completely eliminating the sacrificing layer pattern in the lower part of the plating basis layer.

Description

Liga process and method for manufacturing microstructures using the same {LIGA process and method manufacturing microstructures using the same}

The present invention relates to a LIGA process for forming microstructures.

In general, the LIGA process refers to a fine processing technology consisting of three steps: an X-ray lithography, an electroforming process, and a plastic molding process. Abbreviation of the first letters of the German Lithographie, Galvanoformung and Abformung.

In the X-ray photographic process, X-rays are irradiated and developed on a photoresist using an X-ray mask to develop a fine photoresist structure, and the electroplating process is performed by removing the photoresist from the fabricated fine photoresist structure. Part of the process is to produce a fine metal structure by removing the remaining photoresist film after growing and filling the metal material by using the electroplating method, the injection process is a process of injecting the plastic structure using the produced fine metal structure as a mold.

The advantage of this liga process is that when the photoresist is exposed to light, X-rays (wavelengths in the range of 1 to 10Å) with excellent transparency can be used to fabricate a photoresist structure that can have a height of several hundred μm while maintaining a width of several μm. When using this photoresist structure to produce a metal structure by plating it can be obtained a metal structure of the opposite shape to the photoresist structure, the precision is almost the same as the photoresist structure.

However, in the case of using X-rays as the light source, it is difficult to manufacture a mask because a pattern capable of selectively blocking X-rays must be formed on the mask, thereby increasing manufacturing costs.

The present invention is to solve such a problem, there is a problem in minimizing the manufacturing cost of the Liga process.

1A to 1L are cross-sectional views illustrating a process of manufacturing the microstructure of the first embodiment to which the Riga process according to the present invention is applied, according to a process sequence thereof,

2A to 2I are cross-sectional views illustrating a manufacturing process of a metal structure of a second embodiment to which a Liga process according to the present invention is applied, according to a process sequence thereof.

In the Riga process according to the present invention, the photosensitive film pattern is exposed using ultraviolet light as a light source.

In this case, it is preferable to use SU-8 having excellent photosensitivity such that the photoresist film can have a height of several hundred μm while maintaining a width of several μm, and it is preferable to form a buffer layer before forming the SU-8 photoresist film. Here, it is preferable to use a silicon oxide film, aluminum, or titanium as the buffer layer.

Then, an embodiment of a Riga process and a method of manufacturing a microstructure using the same according to the present invention will be described in detail with reference to the accompanying drawings so that those skilled in the art to which the present invention pertains can be easily carried out.

In the method of manufacturing a microstructure of the Riga process according to the present invention, the light source uses ultraviolet rays, and is exposed and developed by a photo process using a mask to form a photoresist pattern for the microstructure. In this case, it is preferable to use SU-8 having excellent photosensitivity such that the photoresist film can have a height of several hundred μm while maintaining the width of several μm, and has a high thickness and high stress and weakness of the SU-8 photoresist film. It is preferable to form a buffer layer made of a silicon oxide film before forming the photoresist film in order to reinforce the adhesive force. If the material is capable of reinforcing adhesion instead of the silicon oxide film, other materials such as aluminum or aluminum may be used. Titanium or the like can also be used.

In the embodiment using the Liga process of the present invention, a process of forming the microstructure on the upper portion of the substrate using the photosensitive film as a plating frame will be described in detail with reference to the drawings.

1A to 1L are cross-sectional views illustrating a process of manufacturing a microstructure of a first embodiment to which a Liga process according to the present invention is applied, in a process sequence, illustrating a process of forming a micro actuator floated from a substrate. Drawing.

As shown in FIG. 1A, first, an insulating film 20 made of silicon oxide (SiO ₂ ) is formed on the silicon substrate 10. Here, the insulating film 20 may be formed through thermal oxidation, or may be formed through chemical vapor deposition, and may provide insulation between the substrate 10 and the overhanging structure after separation from the substrate 10. Used for.

Subsequently, as shown in FIG. 1B, the sacrificial layer 30 is formed on the insulating film 20 by using a metal material such as aluminum or copper, or polycrystalline silicon. In the case of using aluminum, both vapor deposition and sputtering methods can be used. The reason for the use of such materials is that they are more resistant to heat than with polymers, and therefore, they may have more degrees of freedom in the choice of processes that will follow.

Subsequently, as shown in FIG. 1C, the sacrificial layer pattern 32 having the openings O is formed by patterning using a photolithography process using a mask. In this case, the photolithography process is a general semiconductor manufacturing process using a photoresist pattern as an etching mask, and when the sacrificial layer 30 is made of aluminum, it is preferable to use dry etching. In addition, the photoresist pattern used to form the sacrificial layer pattern 32 is removed by wet etching. During the dry etching forming the sacrificial layer pattern 32, the surface of the photoresist pattern may be hard to be removed by wet etching. have. Therefore, in order to remove the upper portion of the photoresist pattern, it is preferable to perform reactive ion etching using oxygen (O ₂ ), and then remove the photoresist pattern by wet etching.

Subsequently, as shown in FIG. 1D, a plating base layer 40 to be used as a base layer in a subsequent plating process is formed on the substrate 10 using vapor deposition. In this case, the plating base layer 40 preferably uses a metal material, and may be formed as a single film or a multilayer film, and in the case of a multilayer film, preferably includes Au or Cu, and Ti / Au may be one example. have. Here, Ti is used to improve adhesion. Next, a heat treatment step is performed. This is to maintain a uniform etching rate when wet etching is used in the process of patterning the plating base layer 40 formed through the vapor deposition method, and the heat treatment should be within 60 minutes in the range of about 300-400 ° C. Preferably, More preferably, it carries out about 30 minutes in the range of about 330-350 degreeC. In this case, the plating base layer 40 is in contact with the insulating layer 20 in the opening O of the sacrificial layer pattern 32.

Subsequently, as shown in FIG. 1E, a buffer layer 50 is formed on the substrate 10. In this case, since the buffer layer 50 has a high thickness of the photoresist pattern for the microstructure of the plating frame to be formed later, a large stress is generated to absorb the stress, and the plating base layer 40 When the photoresist pattern for a microstructure is directly formed on the upper portion of the photoresist pattern to prevent it from falling off or distorting the photoresist pattern. Here, the silicon oxide film of the buffer layer 50 may be formed, and as the silicon oxide film, a tetraethoxysilane (TEOS) film having good adhesion to both the microstructure of the photoresist film formed later and the underlying plating base layer 50 is formed. It is good to use. The TEOS film not only has better adhesion than other silicon oxide films, but also has good step coverage. Here, instead of the TEOS film can be used a good oxidation material, for example, aluminum (aluminum) or titanium (titanium).

Subsequently, as shown in FIG. 1F, a photoresist film for forming a plating frame of the microstructures is coated on the substrate 10, and then the photoresist film is exposed and developed by a photographic process using a mask to form a plating frame of the microstructures. Form 62. In this case, it is preferable to use SU-8 having excellent photosensitivity with respect to ultraviolet rays in order to form a photoresist pattern 62 having a height of several hundred μm while maintaining a width of several μm while the photoresist maintains a width of several μm. In this case, since ultraviolet rays are used as the light source, there is no need to fabricate an X-ray mask as in the prior art, and manufacturing costs can be significantly reduced. In addition, even when ultraviolet rays are used, the photosensitive film pattern 62 having an excellent precision can be obtained by using the SU-8 photosensitive film having excellent photosensitivity and having a substantially vertical wall surface.

Subsequently, as shown in FIG. 1G, the exposed buffer layer 50 is etched using the photoresist pattern 62 as an etch mask. At this time, the etching is preferably using a dry etching. Here, since the photoresist pattern 62 is used as an etching mask, a mask for etching the buffer layer 50 is not required separately, and the buffer layer 50 is formed in the same shape as the photoresist pattern 62.

On the other hand, as described above, there is a process of removing the buffer layer 50 that is not covered by the photosensitive film pattern 62, it is possible to prevent the photosensitive film remaining in the portion except the photosensitive film pattern 62.

Subsequently, as shown in FIG. 1H, the plating layer 70, which is a microstructure, may be formed of a metal material such as nickel on the plating base layer 40 that is not covered by the photoresist pattern 62 using electrolytic or electroless plating. .

Subsequently, as shown in FIG. 1I, the photoresist pattern 62, which is a plating frame, is removed and the buffer layer 50 underneath is exposed. At this time, it is preferable to use an ashing process which is reactive ion etching.

Subsequently, as shown in FIG. 1J, the remaining buffer layer 50 not covered by the plating layer 70 is removed to expose the underlying plating base layer 40. Here again, there is a process of removing all the remaining buffer layers 50, so that the photoresist film can be prevented from remaining.

Subsequently, as shown in FIG. 1K, the plating base layer 40 not removed by the plating layer 70, which is a microstructure, is removed.

Finally, as shown in FIG. 1L, all of the lower sacrificial layer patterns 32 supporting the plating base layer 40 are removed to complete the microstructure 70 floated from the substrate 10.

Next, a process of manufacturing a fine metal structure with reference to the drawings will be described in detail.

2A to 2I are cross-sectional views illustrating a manufacturing process of the metal structure of the second embodiment to which the Liga process according to the present invention is applied, according to the process sequence, and illustrating a process of forming a micro stamp.

As shown in FIGS. 2A to 2I, an insulating film 20 is formed on the substrate 10, a plating base layer 40 is formed, a buffer layer 50 is formed, and a photosensitive film which is a plating frame of a fine metal structure. A pattern 62 is formed, the exposed buffer layer 50 is etched using the photoresist pattern 62 as an etching mask, a plating layer 70 which is a fine metal structure is formed on the plating base layer 40, and plating is performed. The process of removing the photosensitive film pattern 62, the buffer layer 50, and the plating base layer 40 not covered by the plating layer 70 is identical to that of the first embodiment.

However, in the second exemplary embodiment, unlike the first exemplary embodiment in which the microstructures floated from the substrate 10 are formed, the micrometallic structures are directly formed on the upper portion of the substrate 10, so that the opening O may be formed as shown in FIG. 1C of the first exemplary embodiment. It is not necessary to form a sacrificial layer pattern having). Therefore, as shown in FIG. 2B, a plating base layer 40 is directly formed on the insulating film 20 by using vapor deposition.

Therefore, in the Riga process according to the present invention, the manufacturing cost of the mask used in the photolithography process may be minimized by using ultraviolet rays. In addition, in the photographic process, by using SU-8 having excellent photosensitivity, a precise plating mold can be formed. In addition, by forming a buffer layer having a low stress and excellent adhesion to the lower portion of the photoresist film, and then forming a photoresist pattern as a plating frame, damage to the photoresist pattern may be prevented, and the photoresist may be prevented from remaining by completely removing the buffer layer. .

Claims (15)

Applying a photoresist film on top of the substrate, Exposing the photoresist to ultraviolet light through a mask; Developing the photoresist to form a photoresist pattern that is a plating mold. In claim 1, The photosensitive film is SU-8 Riga process. Forming an insulating film on the substrate, Forming a sacrificial layer on the insulating film; Patterning the sacrificial layer to form a sacrificial layer pattern having openings; Forming a plating base layer on the substrate; Forming a buffer layer on the plating base layer; Applying a photoresist film on top of the buffer layer, Exposing and developing the photoresist with ultraviolet rays through a photolithography process using a mask to form a photoresist pattern as a plating frame of a microstructure; Etching the buffer layer not covered by the photoresist pattern to expose the plating base layer; Forming a plating layer that is a microstructure on top of the plating base layer, Removing the photoresist pattern; Removing all of the buffer layers; Removing the plating base layer not covered by the plating layer, Removing all of the sacrificial layer patterns under the plating base layer Riga process comprising a. In claim 3, The insulating film is formed by thermal oxidation. In claim 4, The sacrificial layer is formed of aluminum, copper or polysilicon. In claim 5, The sacrificial layer pattern is formed by dry etching. In claim 6, The method further comprises a reactive ion etch using oxygen (O ₂ ) before forming the sacrificial layer pattern. In claim 7, The plating base layer is a Liga process of forming a single layer of Cu, Au, Cr, Ni, Ti or a double layer thereof. In claim 8, After the plating base layer forming step, the plating base layer further comprises a heat treatment process. In claim 9, The said heat treatment process is a Riga process performed in the range of about 300-400 degreeC. In claim 10, A Riga process which performs the said heat processing process within 60 minutes. In claim 11, Riga process of forming the buffer layer of a tetraethoxysilane (TEOS) film or aluminum (aluminum) or titanium (titanium). In claim 12, The photosensitive film is a Riga process using SU-8. In claim 13, Riga process of forming the buffer layer of a tetraethoxysilane (TEOS) film or aluminum (aluminum) or titanium (titanium). Forming an insulating film on the substrate, Forming a plating base layer on the insulating layer; Forming a buffer layer on the plating base layer; Applying a photoresist film on top of the buffer layer, Exposing and developing the photoresist with ultraviolet rays through a photolithography process using a mask to form a photoresist pattern as a plating frame of a microstructure; Etching the buffer layer not covered by the photoresist pattern to expose the plating base layer; Forming a plating layer that is a microstructure on top of the plating base layer, Removing the photoresist pattern; Removing all of the buffer layers; Removing the plating base layer not covered by the plating layer, Riga process comprising a.