JP3952795B2 - Resist film pattern forming method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resist film pattern forming method, and in particular, in a process of manufacturing a printed wiring board, pattern forming a resist film that serves as a mask in the process of pattern-etching a conductive layer to be processed on the board and patterning a wiring portion. On how to do.
[0002]
[Prior art]
In recent years, along with demands for higher integration and higher functionality of semiconductor devices, miniaturization of element structures of semiconductor devices has progressed. Correspondingly, the demand for miniaturization is increasing in the wiring portion of a printed wiring board on which a semiconductor device is mounted, and research and development are being conducted.
[0003]
As a resist film pattern forming method for forming the above-mentioned fine pattern printed wiring portion, for example, a resist film is formed on an upper layer of a conductive layer to be processed formed on a substrate such as a plastic substrate, and then exposed. A method of performing pattern exposure by contact exposure using a glass mask on which a pattern is formed and developing is widely performed.
In addition, a method of pattern exposure by non-contact exposure represented by a stepper and development is widely performed.
[0004]
Furthermore, a method is also known in which pattern exposure is performed by a direct drawing apparatus using a laser beam and development is performed.
[0005]
[Problems to be solved by the invention]
However, in the resist film pattern forming method by the above contact exposure, when forming on the upper layer of the conductive layer to be processed on the plastic substrate, the size of the substrate itself may be changed by an external atmosphere such as a greenhouse temperature, Since there are minute irregularities on the surface, even if an expensive glass mask is used, the pattern of the resist film that has been patterned does not match due to changes in the dimensions of the substrate, or light wraps around due to minute irregularities on the surface. The exposed area was blurred and it was difficult to form a fine pattern.
[0006]
Further, in the resist film pattern forming method by non-contact exposure described above, an expensive glass mask is used in the same manner as described above, and it is necessary to replace the mask when changing the model, so that the manufacturing cost is high.
[0007]
Further, the resist film pattern forming method by direct drawing using the laser beam has a problem that productivity is lowered because a long time is required for drawing.
In order to avoid this problem, the resist film may be thinned. However, if the object to be etched is a surface with irregularities such as a plastic substrate, the resist film cannot follow the surface shape and the yield is increased. The problem of being easy to drop arises.
[0008]
In addition, a method of exposing, developing, and etching by using a visible light photosensitive resist film is also conceivable. However, since visible light has a low energy level, it is necessary to make the photosensitive film thin. In this case, a plastic substrate is used. It becomes difficult to follow the unevenness of the. On the other hand, when the photosensitive film is thickened, the exposure time becomes longer and the productivity becomes worse.
[0009]
Similarly, when using a visible light photosensitive resist film as a plating resist film, similarly, in order to ensure the plating solution resistance of the visible light photosensitive resist film, the film thickness is increased and the energy level is increased. Is necessary, and productivity is poor. On the other hand, if the thickness is reduced, the dam as the plating resist film is insufficient and the plating solution resistance cannot be ensured.
[0010]
The present invention has been made in view of such circumstances, and an object thereof is to provide a resist film pattern forming method that can be produced with improved productivity and yield without using an expensive glass mask. .
[0011]
[Means for Solving the Problems]
In order to achieve the above object, a method for forming a resist film pattern according to the present invention includes a first film with a cover film that is transparent to at least a first wavelength of light on a resist film pattern forming surface. A step of forming a first resist film that is sensitive to light of the first wavelength from the first resist film side, and forming a first resist film on the cover film that is impermeable to light of the first wavelength, Forming a second resist film that is sensitive to light having a second wavelength different from the first wavelength, and pattern exposing the second resist film with light having the second wavelength using a liquid crystal mask And a step of developing the second resist film, allowing the light of the first wavelength to pass through the cover film, and pattern-exposing the first resist film using the developed second resist film as a mask. Process And removing the second resist film at the same time as the cover film, and a step of developing the first resist film, a resist film is patterned on forming surface of the pattern of the resist film.
[0012]
In the resist film pattern forming method of the present invention, preferably, the light having the first wavelength is light in the ultraviolet region, and the light having the second wavelength is light in the visible light region.
[0013]
In the resist film pattern forming method of the present invention, preferably, in the step of pattern exposure of the second resist film, exposure is performed by a direct projection method using the liquid crystal mask.
Alternatively, preferably, in the step of pattern exposure of the second resist film, exposure is performed by a hologram method using the liquid crystal mask.
Alternatively, preferably, in the pattern exposure process of the second resist film, the liquid crystal mask is used to perform exposure by a phase contrast method.
[0014]
In the resist film pattern forming method of the present invention, preferably, before the step of forming the first resist film sensitive to the light having the first wavelength, the dimension of the resist film pattern forming surface is set. And measuring the pattern size of the liquid crystal mask so that the pattern conforms to the measured dimension of the resist film pattern forming surface in the pattern exposure step of the second resist film. To expose.
[0015]
In the resist film pattern forming method of the present invention, preferably, the step of removing the second resist film and the step of developing the first resist film are simultaneously performed.
[0017]
In the resist film pattern forming method of the present invention, preferably, the resist film pattern forming surface is the surface of the conductive film provided on the substrate.
More preferably, the substrate is a flexible substrate wound up in a reel shape, and the above steps are performed while being pulled out from the reel and wound up on the reel.
[0018]
In the resist film pattern forming method of the present invention, preferably, the pixel pitch lattice of the liquid crystal mask is designed as the pattern of the liquid crystal mask to obtain the above pattern.
[0019]
In the above resist film pattern forming method of the present invention, a first resist film that is sensitive to light having a first wavelength is formed on a resist film pattern forming surface, and then, over the first resist film. A second resist film that is impermeable to light of the first wavelength and is sensitive to light of a second wavelength different from the first wavelength is formed.
Next, the second resist film is subjected to pattern exposure using light of a second wavelength using a liquid crystal mask, and the second resist film is developed.
Next, the first resist film is subjected to pattern exposure with light of the first wavelength using the developed second resist film as a mask, the second resist film is removed, and the first resist film is developed.
By the above process, a resist film serving as an etching mask is patterned on the surface to be patterned.
[0020]
According to the resist film pattern forming method of the present invention, the liquid crystal mask is used for the exposure of the second resist film, and the second resist film is used as the mask for the exposure of the first resist film. An expensive glass mask is unnecessary.
Since the first resist film is actually used as a mask for etching and plating, the second resist film may be formed thin as long as it can block ultraviolet rays. On the other hand, the first resist film adopts a resist film that is sensitive to light in the ultraviolet region, so that even when the film is formed thick, exposure at a high energy level can be performed and productivity is increased. Can do.
Therefore, it is possible to improve productivity and yield without using an expensive glass mask.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of a resist film pattern forming method according to reference examples and embodiments of the present invention will be described below with reference to the drawings.
[0022]
Reference Example FIG. 1A is a plan view of a printed wiring board manufactured using the resist film pattern forming method of this reference example , and FIG. 1B is a cross-sectional view taken along line XX ′ in FIG. FIG.
For example, a wiring portion 11a made of copper or the like processed into a wiring pattern is formed on one surface of an insulating substrate 10 made of a thermosetting resin such as an epoxy resin or other resins.
[0023]
A method for manufacturing the printed wiring board using the resist film pattern forming method of this reference example will be described with reference to the drawings.
First, as shown in FIG. 2A, several to several conductive layers 11 such as copper foil are formed on one surface of an insulating substrate 10 made of a thermosetting resin such as an epoxy resin or other resins. It is formed with a film thickness of 10 μm.
The conductive layer 11 can be formed by any method such as pasting, plating, vapor phase growth, and the like.
With respect to the substrate 10 on which the conductive layer 11 is formed, the length measuring device 20 measures the distance between the reference marks for each substrate, and calculates the correction factor.
[0024]
Next, as shown in FIG. 2B, an ultraviolet curable resist material is applied to form a first resist film 12.
As the UV curable resist material, for example, “TSGGR series” manufactured by Tokyo Ohka Kogyo Co., Ltd. or “AS series” manufactured by Taiyo Ink Co., Ltd. can be used, and spin coating, screen printing, or curtain coating can be used. The film can be formed by coating by a method or the like.
[0025]
Next, as shown in FIG. 2 (c), a visible light curable resist material is applied by spin coating, screen printing, roll coating, curtain coating, or the like. 2 A resist film 13 is formed.
The visible light curable resist material contains a photosensitive resin, a photoreaction initiator, a photosensitizer, and fine particles of titanium oxide or calcium carbonate having an ultraviolet shielding ability.
[0026]
Examples of the photosensitive resin include resins such as polyvinyl alcohol resin, polyvinyl ether resin, polyvinyl pyrrolidone resin, acrylic resin, urethane resin, polyester resin, and hydantoin-containing resin. For example, at least two unsaturated bonds are introduced. Thus, a resin exhibiting photosensitivity can be used.
As needed, you may use together the compound which has at least 1 unsaturated bond, such as an acrylic monomer and a vinyl monomer.
As the photosensitive resin, it is possible to use a resin other than the above-described resins.
[0027]
The photoinitiator is a photoinitiator having a large absorption in the visible light region, such as benzyl, α-naphthyl, acenaphthane, 4,4′-dimethoxybenzyl, 4,4′-dicyclobenzyl. Benzyl compounds such as quinone compounds, quinone compounds such as camphorquinone, thioxanthone compounds such as 2-chlorothioxanthone, 2,4-diethoxythioxanthone, methylthioxanthone, acylphosphine oxide compounds such as trimethylbenzoyldiphenylphosphine oxide, etc. Can do.
[0028]
Examples of the photosensitizer include amine compounds such as dimethylaminoethyl methacrylate, isoamyl 4-dimethylaminobenzoate, n-butylamine and triethylamine, phosphine compounds such as triethyl-n-butylphosphine, and a visible light portion. Dyes with absorption can be used.
[0029]
The fine particles of titanium oxide or calcium carbonate having the above-mentioned ultraviolet shielding ability have an average particle size of 0.1 μm or less, preferably 0.05 μm or less. If the average particle size is too large, not only ultraviolet rays but also visible light is blocked, which is not preferable.
In order to sufficiently block ultraviolet rays, the mixing ratio of the titanium oxide or calcium carbonate fine particles in the resist material is, for example, 30% by weight or more when the film thickness as the second resist film 13 is about 5 μm. When the thickness is about 10 μm, the content is 15% by weight or more.
[0030]
After forming the second resist film 13 as described above, as shown in FIG. 3A, exposure is performed by irradiating the visible light laser VIS having a wavelength of 436 to 532 nm, for example, 514 nm using the liquid crystal mask 21 as a mask. To do. As the exposure wavelength at this time, an optimum wavelength can be selected according to the absorption wavelength of the photoreaction initiator contained in the second resist film.
As a method for forming an exposure pattern, a direct projection method, a hologram method, a phase contrast method, or the like can be used.
Here, the pattern is drawn on the liquid crystal mask 21 so that the pattern conforms to the dimension of the formation surface of the conductive layer 11, which is the formation surface of the resist film, from the correction rate obtained as a result of measurement by the length measuring device 20 described above. The exposure is carried out by adjusting the pattern size.
By the exposure described above, the second resist film 13a in the exposed region is cured and becomes a region that is not removed by development, but the second resist film 13b in the unexposed region is not cured and is subjected to development processing. Will be removed.
[0031]
In drawing with a liquid crystal mask, the size of an exposure pattern becomes variable, and an object to be exposed can be measured one by one, and exposure can be performed with matching dimensions. Therefore, higher alignment accuracy than before can be obtained.
Liquid crystal miniaturization requires liquid crystal with a large number of pixels. To compensate for this, design rules for liquid crystal pixel pitch grids are used instead of the conventional millimeter grid and inch grid designs. I do.
[0032]
After the exposure as described above, as shown in FIG. 3B, development processing is performed to dissolve unexposed portions. As a result, the second resist film 13a in the exposed and cured region is left as a resist pattern.
As the developing solution, it is preferable to use water in view of the influence on the first resist film 12 as a base. For example, the developing solution is treated by running water for 10 to 20 seconds or by spraying water for 10 to 60 seconds.
[0033]
Next, as shown in FIG. 4A, the entire surface is irradiated with ultraviolet rays UV having a wavelength of 365 nm, for example, with an appropriate exposure wavelength and exposure amount according to the type of material of the first resist film to be used. .
Since the second resist film 13a contains fine particles of titanium oxide or calcium carbonate as described above and has an ultraviolet shielding ability, the second resist film 13a is used as a mask when pattern exposure is performed by irradiating ultraviolet rays. be able to.
By the exposure described above, the first resist film 12a in the exposed region is cured and becomes a region that is not removed even by development, but the first resist film 12b in the unexposed region is not cured and is subjected to development processing. Will be removed.
[0034]
Next, as shown in FIG. 4B, an appropriate development process corresponding to the type of material of the first resist film to be used is performed to dissolve the unexposed portion. Thus, the first resist film 12a in the exposed and cured region is left as a resist pattern. In this development process, the second resist film 13a is also removed at the same time.
As the developer, for example, an aqueous sodium carbonate solution can be used.
[0035]
Next, as shown in FIG. 4C, an etching process is performed using the first resist film 12a as a mask, and the conductive layer 11 is patterned to form the wiring portion 11a.
As subsequent steps, the first resist film 12a can be removed by, for example, organic solvent treatment, and the printed wiring board having the configuration shown in FIG. 1 can be formed.
[0036]
According to the resist film pattern forming method used in the printed wiring board manufacturing method according to this reference example , the liquid crystal mask is used for the exposure of the second resist film, and the first resist film is exposed for the first time. 2 Since a resist film is used as a mask, it is not necessary to create an expensive glass mask or mask film, and the cost for mask formation can be saved.
Further, since the first resist film is actually used as an etching mask, the second resist film may be formed thin as long as it can block ultraviolet rays. On the other hand, the first resist film is a resist film that is sensitive to light in the ultraviolet region, so that the selectivity of the resin is wide depending on the application, thickness, and productivity, and even when the film thickness is formed thick. It is possible to perform exposure at a high energy level and increase productivity.
In this way, it is possible to improve productivity and yield without using an expensive glass mask.
[0037]
Since the resist film pattern forming method according to the present reference example does not use a fixed mask, the mask replacement operation at the time of model switching is not required.
In particular, the board is a flexible board wound up in a reel shape, and this flexible board is pulled out from the reel, and the above-mentioned processes are performed while winding up the reel. Although materials were wasted for switching, in this reference example, it was possible to change models quickly by simply changing the data of the liquid crystal mask without using a fixed mask, and it was possible to use materials without waste. Become.
[0038]
Further, since the distance between the reference marks is measured for each substrate by the length measuring device, the correction factor is calculated, and the exposure is performed, it is possible to perform the exposure with high accuracy.
[0039]
Embodiment A printed wiring board manufactured using the resist film pattern forming method of the present embodiment is the same as the printed wiring board according to the reference example shown in FIG.
Hereinafter, a method for manufacturing the printed wiring board using the resist film pattern forming method of the present embodiment will be described with reference to the drawings.
[0040]
First, as shown in FIG. 5A, several to several conductive layers 11 such as copper foil are formed on one surface of an insulating substrate 10 made of a thermosetting resin such as an epoxy resin or other resins. With respect to the substrate 10 formed with a film thickness of 10 μm and having the conductive layer 11 formed thereon, the distance between the reference marks is measured for each substrate by the length measuring device 20, and the correction factor is calculated.
[0041]
Next, as shown in FIG. 5B, an ultraviolet transmissive cover film 14 and a dry film resist 15 made of an ultraviolet curable resist material (first resist film 12) are bonded together.
As the dry film resist, for example, “Sunfort Series” manufactured by Asahi Kasei Kogyo Co., Ltd. or “NIT Series” manufactured by Nichigo Morton Co., Ltd. can be used.
[0042]
Next, as shown in FIG. 5C, a visible light curable resist material is applied to the upper layer of the cover film 14 by spin coating, screen printing, roll coating, curtain coating, or the like. A second resist film 13 is formed with a thickness of 10 μm.
As the visible light curable resist material, the same material as in the reference example can be used.
[0043]
After the second resist film 13 is formed as described above, as shown in FIG. 6A, the visible light laser VIS having a wavelength of 400 nm or more, for example, 436 to 532 nm is irradiated using the liquid crystal mask 21 as a mask. , Expose. As the exposure wavelength at this time, an optimum wavelength can be selected according to the absorption wavelength of the photoreaction initiator contained in the second resist film.
As a method for forming an exposure pattern, a direct projection method, a hologram method, a phase contrast method, or the like can be used.
Here, the pattern is drawn on the liquid crystal mask 21 so that the pattern conforms to the dimension of the formation surface of the conductive layer 11, which is the formation surface of the resist film, from the correction rate obtained as a result of measurement by the length measuring device 20 described above. The exposure is carried out by adjusting the pattern size.
By the exposure described above, the second resist film 13a in the exposed region is cured and becomes a region that is not removed by development, but the second resist film 13b in the unexposed region is not cured and is subjected to development processing. Will be removed.
[0044]
In drawing with a liquid crystal mask, the size of an exposure pattern becomes variable, and an object to be exposed can be measured one by one, and exposure can be performed with matching dimensions. Therefore, higher alignment accuracy than before can be obtained.
Liquid crystal miniaturization requires liquid crystal with a large number of pixels. To compensate for this, design rules for liquid crystal pixel pitch grids are used instead of the conventional millimeter grid and inch grid designs. I do.
[0045]
After the exposure as described above, as shown in FIG. 6 (b), as a development process, for example, the process is performed for 10 to 20 seconds with running water, or the water is sprayed for 10 to 60 seconds, and the unexposed part is removed. Dissolve. As a result, the second resist film 13a in the exposed and cured region is left as a resist pattern.
[0046]
Next, as shown in FIG. 6C, the entire surface is irradiated with ultraviolet light UV having a wavelength of 365 nm, for example, with an appropriate exposure wavelength and exposure amount according to the type of material of the first resist film to be used. .
Since the second resist film 13a contains fine particles of titanium oxide or calcium carbonate as described above and has an ultraviolet shielding ability, the second resist film 13a is used as a mask when pattern exposure is performed by irradiating ultraviolet rays. be able to.
As a result of the exposure described above, the first resist film 12a in the region exposed by the ultraviolet light transmitted through the cover film 14 is cured and becomes a region that is not removed by development, but the first resist film 12b in the unexposed region is cured. However, they are removed by development processing.
[0047]
Next, as shown in FIG. 7A, the cover film 14 is peeled off at the interface with the first resist film 12 and removed.
At this time, the second resist film 13 a used as the exposure mask is also removed together with the cover film 14.
[0048]
Next, as shown in FIG. 7B, an appropriate development process according to the type of material of the first resist film to be used is performed to dissolve the unexposed portion. Thus, the first resist film 12a in the exposed and cured region is left as a resist pattern.
As the developer, for example, an aqueous sodium carbonate solution can be used.
[0049]
Next, as shown in FIG. 7C, an etching process is performed using the first resist film 12a as a mask, and the conductive layer 11 is patterned to form a wiring portion 11a.
As subsequent steps, the first resist film 12a can be removed by, for example, organic solvent treatment, and the printed wiring board having the configuration shown in FIG. 1 can be formed.
[0050]
According to the resist film pattern forming method used in the method for manufacturing a printed wiring board according to the present embodiment, as in the first embodiment, an expensive glass mask is not used, and productivity and yield are improved. It is possible.
[0051]
The present invention is not limited to the above embodiment.
For example, in the above embodiment, the first resist film is used as an etching mask. However, the present invention is not limited to this, and the first resist film can be used as a plating resist.
In addition, the material contained in the first resist film is not limited to the above material, and other materials having the same function can be used.
In addition, various modifications can be made without departing from the scope of the present invention.
[0052]
【The invention's effect】
As described above, according to the resist film pattern forming method of the present invention, the liquid crystal mask is used for the exposure of the second resist film, and the second resist film is used for the exposure of the first resist film. Therefore, an expensive glass mask is unnecessary. Since the first resist film is actually used as a mask for etching and plating, the second resist film may be formed thin as long as it can block ultraviolet rays. On the other hand, the first resist film adopts a resist film that is sensitive to light in the ultraviolet region, so that even when the film is formed thick, exposure at a high energy level can be performed and productivity is increased. Can do. Therefore, it is possible to improve productivity and yield without using an expensive glass mask.
[Brief description of the drawings]
FIG. 1A is a plan view of a printed wiring board manufactured by using a resist film pattern forming method according to a reference example and an embodiment of the present invention, and FIG. 1B is a plan view of FIG. It is sectional drawing in alignment with XX '.
FIGS. 2A to 2C are cross-sectional views showing the steps of a method for manufacturing a printed wiring board using a resist film pattern forming method according to a reference example .
3 (a) and 3 (b) are cross-sectional views showing a continuation step of FIG.
4 (a) to 4 (c) are cross-sectional views showing a step subsequent to FIG.
FIGS. 5A to 5C are cross-sectional views illustrating steps of a method for manufacturing a printed wiring board using a resist film pattern forming method according to an embodiment of the present invention .
6 (a) to 6 (c) are cross-sectional views showing a step subsequent to FIG.
FIGS. 7A to 7C are cross-sectional views showing a process continued from FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 ... Board | substrate, 11 ... Conductive layer, 11a ... Wiring layer, 12, 12a, 12b ... 1st resist film, 13, 13a, 13b ... 2nd resist film, 14 ... Cover film, 15 ... Dried film resist, 20 ... Measurement Long device, 21 ... liquid crystal mask, VIS ... visible light laser, UV ... ultraviolet light.

Claims (10)

A first resist film that is sensitive to light of the first wavelength with a cover film that is transparent to at least light of the first wavelength is formed on the resist film pattern forming surface from the first resist film side. A process of bonding and forming,
Forming a second resist film on the cover film that is impermeable to light of the first wavelength and is sensitive to light of a second wavelength different from the first wavelength;
Pattern exposure of the second resist film using a liquid crystal mask with light of the second wavelength;
Developing the second resist film;
Passing the first wavelength light through the cover film and pattern-exposing the first resist film using the developed second resist film as a mask;
Removing the second resist film simultaneously with the cover film ;
Developing the first resist film,
A resist film pattern forming method, wherein a resist film is patterned on a resist film pattern forming surface. The light of the first wavelength is light in the ultraviolet region,
The resist film pattern forming method according to claim 1, wherein the light of the second wavelength is light in a visible light region. The resist film pattern forming method according to claim 1, wherein in the step of pattern exposure of the second resist film, exposure is performed by a direct projection method using the liquid crystal mask. The resist film pattern formation method according to claim 1, wherein in the step of pattern exposure of the second resist film, exposure is performed by a hologram method using the liquid crystal mask. The resist film pattern forming method according to claim 1, wherein in the step of pattern exposure of the second resist film, exposure is performed by a phase contrast method using the liquid crystal mask. Before the step of forming the first resist film sensitive to the light of the first wavelength, further comprising the step of measuring the dimension of the pattern formation surface of the resist film,
The pattern exposure of the second resist film is performed by adjusting the pattern dimension of the liquid crystal mask so that the pattern matches the measured dimension of the pattern formation surface of the resist film. Resist film pattern forming method. The method for forming a resist film pattern according to claim 1, wherein the step of removing the second resist film and the step of developing the first resist film are simultaneously performed. The resist film pattern forming method according to claim 1, wherein the resist film pattern forming surface is a surface of a conductive film provided on a substrate . The substrate is a flexible substrate wound in a reel shape,
The resist film pattern forming method according to claim 8 , wherein each of the steps is performed while being pulled out from the reel and wound on the reel . Above as a pattern of the liquid crystal mask, the design of the pixel pitch grating of the liquid crystal mask, the patterning of the resist film according to claim 1, the pattern.

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